Thresholds of Daily Precipitation in Texas

Water-Resources Investigations Report 03–4281

U.S. Department of the Interior

U.S. Geological Survey
 Technical Report Documentation Page 

1. Report No. 

0-4193-5 

2. Government Accession No. 3. Recipient’s Catalog No. 

5. Report Date 

 December 2003

4. Title and Subtitle 

ATLAS OF INTEROCCURRENCE INTERVALS FOR 

SELECTED THRESHOLDS OF DAILY PRECIPITATION IN 

TEXAS 6. Performing Organization Code 

7. Author(s) 

William H. Asquith and Meghan C. Roussel 

8. Performing Organization Report No. 

 WRIR 03–4281 

9. Performing Organization Name and Address 10. Work Unit No. (TRAIS) 

 U.S. Geological Survey 

 Water Resources Division 

 8027 Exchange Drive 

 Austin, Texas 78754 

11. Contract or Grant No. 

 Project 0-4193 

13. Type of Report and Period Covered 

 Research from 2002 to 2003 

12. Sponsoring Agency Name and Address 

Texas Department of Transportation U.S. Geological Survey 

Research and Technology Implementation Office Water Resources Division

4000 Jackson Ave., Bldg. 1 8027 Exchange Drive 

P.O. Box 5080 Austin, Texas 78754 

Austin, TX 78731 

14. Sponsoring Agency Code 

15. Supplementary Notes 

 Project conducted in cooperation with the Federal Highway Administration. 

16. Abstract 

The U.S. Geological Survey, in cooperation with the Texas Department of Transportation, has produced maps depicting 

the magnitude and spatial variation of interoccurrence intervals in days of daily precipitation exceeding selected 

thresholds in Texas. In the report, a Poisson model of precipitation interoccurrence intervals is described. A 

precipitation interoccurrence interval is the time period between two successive rainfall events. Events are defined as 

daily precipitation equaling or exceeding a specified depth threshold. Ten precipitation thresholds are considered: 0.05, 

0.10, 0.25, 0.50, 0.75, 1.0, 1.5, 2.0, 2.5, and 3.0 inches. Site-specific mean interoccurrence interval and ancillary 

statistics are presented for each threshold and for each of 1,306 National Weather Service daily precipitation gages. 

Maps depicting the spatial variation across Texas of the mean interoccurrence interval for each threshold are presented. 

Influence of elevation in west Texas and intra-annual variations or month-to-month differences in interoccurrence 

interval are documented. 

17. Key Words 

Precipitation, Interoccurrence interval, Poisson process, 

Poisson distribution, Exponential distribution, National 

Weather Service rain gage, Texas 

18. Distribution Statement 

No restrictions. This document is available to the public 

through the U.S. Geological Survey, Information 

Services, Box 25286, Denver CO 80225–0286. 

19. Security Classif. (of report) 

 Unclassified 

20. Security Classif. (of this page) 

 Unclassified 

21. No. of pages 

204 

22. Price 

$4.00 

Form DOT F 1700.7 (8-72) Reproduction of completed page authorized 

Cover: Summer thunderstorm viewed from southeast Austin facing north, mid-1990s (photograph by Lynne 

Fahlquist, U.S. Geological Survey). 
U.S. Department of the Interior

U.S. Geological Survey

Atlas of Interoccurrence Intervals for Selected 

Thresholds of Daily Precipitation in Texas

By William H. Asquith and Meghan C. Roussel 

U.S. GEOLOGICAL SURVEY

Water-Resources Investigations 03–4281

In cooperation with the Texas Department of Transportation

Austin, Texas

2003
ii

U.S. DEPARTMENT OF THE INTERIOR

Gale A. Norton, Secretary

U.S. GEOLOGICAL SURVEY

Charles G. Groat, Director

Any use of trade, product, or firm names is for 

descriptive purposes only and does not imply 

endorsement by the U.S. Government.

For additional information write to

District Chief

U.S. Geological Survey

8027 Exchange Dr.

Austin, TX 78754–4733

E-mail: dc_tx@usgs.gov

Copies of this report can be purchased from

U.S. Geological Survey

Information Services

Box 25286

Denver, CO 80225–0286

E-mail: infoservices@usgs.gov
CONTENTS iii

CONTENTS

Abstract ................................................................................................................................................................................ 1

Introduction .......................................................................................................................................................................... 1

Data Sources ............................................................................................................................................................. 1

Previous Studies ....................................................................................................................................................... 2

Approach .............................................................................................................................................................................. 3

Site-Specific Interoccurrence Intervals ..................................................................................................................... 3

Regionalization of Interoccurrence Intervals ............................................................................................................ 5

Interoccurrence Intervals for Selected Daily Precipitation Thresholds in Texas ................................................................. 6

Statewide Interoccurrence Interval Maps ................................................................................................................. 6

Influence of Elevation on Interoccurrence Intervals West of the Pecos River ......................................................... 9

Intra-Annual Variations in Interoccurrence Intervals ............................................................................................... 11

Example Applications .......................................................................................................................................................... 14

Site-Specific Median 6-Month Daily Precipitation Threshold ................................................................................. 15

Site-Specific Median Number of Occurrences ......................................................................................................... 29

Intra-Annual Variations in Interoccurrence Intervals ............................................................................................... 31

Regional Estimation of Mean Interoccurrence Interval ............................................................................................ 31

Summary .............................................................................................................................................................................. 32

Selected References ............................................................................................................................................................. 32

FIGURES

1. Map showing locations of 1,306 National Weather Service daily precipitation stations in Texas ....................... 2

2. Example of abbreviated time series of daily precipitation for station 428 Austin Camp Mabry ......................... 3

3. Example interoccurrence interval computations for a hypothetical data set ........................................................ 4

4–13. Maps showing interoccurrence interval for a: 

4. 0.05-inch and greater daily precipitation threshold for Texas ................................................................... 7

5. 0.10-inch and greater daily precipitation threshold for Texas ................................................................... 8

6. 0.25-inch and greater daily precipitation threshold for Texas ................................................................... 9

7. 0.50-inch and greater daily precipitation threshold for Texas ................................................................... 10

8. 0.75-inch and greater daily precipitation threshold for Texas ................................................................... 11

9. 1.0-inch and greater daily precipitation threshold for Texas ..................................................................... 12

10. 1.5-inch and greater daily precipitation threshold for Texas ..................................................................... 13

11. 2.0-inch and greater daily precipitation threshold for Texas ..................................................................... 14

12. 2.5-inch and greater daily precipitation threshold for Texas ..................................................................... 15

13. 3.0-inch and greater daily precipitation threshold for Texas ..................................................................... 16

14a–j. Graphs showing relation between interoccurrence interval and elevation west of the Pecos River, west 

Texas ..................................................................................................................................................................... 17

15–24. Boxplots showing distribution of ratio of interoccurrence interval for month to mean interoccurrence 

interval for period of record at station for a: 

15. 0.05-inch and greater daily precipitation threshold for Texas ................................................................... 18

16. 0.10-inch and greater daily precipitation threshold for Texas ................................................................... 19

17. 0.25-inch and greater daily precipitation threshold for Texas ................................................................... 20

18. 0.50-inch and greater daily precipitation threshold for Texas ................................................................... 21

19. 0.75-inch and greater daily precipitation threshold for Texas ................................................................... 22

20. 1.0-inch and greater daily precipitation threshold for Texas ..................................................................... 23

21. 1.5-inch and greater daily precipitation threshold for Texas ..................................................................... 24

22. 2.0-inch and greater daily precipitation threshold for Texas ..................................................................... 25

23. 2.5-inch and greater daily precipitation threshold for Texas ..................................................................... 26

24. 3.0-inch and greater daily precipitation threshold for Texas ..................................................................... 27
iv 

25–28. Graphs showing: 

25. Relation between adjusted mean and median interoccurrence ratios and month for 0.05- and 

0.10-inch daily precipitation thresholds for Texas ..................................................................................... 28

26. Relation between adjusted mean interoccurrence ratio and month for 0.25-, 0.50-, 0.75-, 1.0-, 

1.5-, 2.0-, 2.5-, and 3.0-inch daily precipitation thresholds for Texas ....................................................... 29

27. Relation between adjusted median interoccurrence ratio and month for 0.25-, 0.50-, 0.75-, 1.0-, 

1.5-, 2.0-, 2.5-, and 3.0-inch daily precipitation thresholds for Texas ....................................................... 30

28. Relation between site-specific daily precipitation threshold and mean interoccurrence interval for 

station 428 Austin Camp Mabry and estimated median 6-month precipitation ........................................ 31

TABLES

1. Summary of National Weather Service daily precipitation stations in Texas with known names, latitudes, 

and longitudes ....................................................................................................................................................... 33

2. National Weather Service daily precipitation stations in Texas, by county .......................................................... 59

3. Summary of interoccurrence intervals for daily precipitation thresholds of 0.05 and 0.10 inch .......................... 62

4. Summary of interoccurrence intervals for daily precipitation thresholds of 0.25 and 0.50 inch .......................... 90

5. Summary of interoccurrence intervals for daily precipitation thresholds of 0.75 and 1.0 inch ............................ 116

6. Summary of interoccurrence intervals for daily precipitation thresholds of 1.5 and 2.0 inches .......................... 142

7. Summary of interoccurrence intervals for daily precipitation thresholds of 2.5 and 3.0 inches .......................... 170

8. Example computation steps of interoccurrence intervals for a Poisson process described in text ....................... 198

9. Summary of statewide interoccurrence interval statistics and diagnostic statistics of interoccurrence 

interval maps ......................................................................................................................................................... 198

10. Summary of interoccurrence ratios by month for 0.05-inch and greater daily precipitation threshold ................ 199

11. Summary of interoccurrence ratios by month for 0.10-inch and greater daily precipitation threshold ................ 199

12. Summary of interoccurrence ratios by month for 0.25-inch and greater daily precipitation threshold ................ 200

13. Summary of interoccurrence ratios by month for 0.50-inch and greater daily precipitation threshold ................ 200

14. Summary of interoccurrence ratios by month for 0.75-inch and greater daily precipitation threshold ................ 201

15. Summary of interoccurrence ratios by month for 1.0-inch and greater daily precipitation threshold .................. 201

16. Summary of interoccurrence ratios by month for 1.5-inch and greater daily precipitation threshold .................. 202

17. Summary of interoccurrence ratios by month for 2.0-inch and greater daily precipitation threshold .................. 202

18. Summary of interoccurrence ratios by month for 2.5-inch and greater daily precipitation threshold .................. 203

19. Summary of interoccurrence ratios by month for 3.0-inch and greater daily precipitation threshold .................. 203

20. Regional estimates of mean interoccurrence interval of precipitation for Austin, Texas ..................................... 204

CONVERSION FACTORS AND VERTICAL DATUM

Multiply By To obtain

foot (ft) 0.3048 meter (m)

inch (in.) 25.40 millimeter (mm)

mile (mi) 1.609 kilometer (km)

Vertical coordinate information is referenced to the National Geodetic Vertical Datum of 1929 (NGVD 29). 
Abstract 1

Atlas of Interoccurrence Intervals for Selected 

Thresholds of Daily Precipitation in Texas

By William H. Asquith and Meghan C. Roussel

Abstract

A Poisson process model is used to define 

the distribution of interoccurrence intervals of daily 

precipitation in Texas. A precipitation interoccurrence interval is the time period between two successive rainfall events. Rainfall events are defined 

as daily precipitation equaling or exceeding a specified depth threshold. Ten precipitation thresholds 

are considered: 0.05, 0.10, 0.25, 0.50, 0.75, 1.0, 

1.5, 2.0, 2.5, and 3.0 inches. Site-specific mean 

interoccurrence interval and ancillary statistics are 

presented for each threshold and for each of 1,306 

National Weather Service daily precipitation 

gages. Maps depicting the spatial variation across 

Texas of the mean interoccurrence interval for each 

threshold are presented. The percent change from 

the statewide standard deviation of the interoccurrence intervals to the root-mean-square error 

ranges from a magnitude minimum of (negative) 

-24 to a magnitude maximum of -60 percent for 

the 0.05- and 2.0-inch thresholds, respectively. 

Because of the substantial negative percent change, 

the maps are considered more reliable estimators of 

the mean interoccurrence interval for most locations in Texas than the statewide mean values. 

INTRODUCTION

A precipitation interoccurrence interval is the 

time period between two successive rainfall events. 

Rainfall events are defined as daily precipitation equaling or exceeding a depth threshold. Estimation of the 

interoccurrence interval for selected depth thresholds in 

Texas can be useful in developing hydrologic models, in 

enhancing guidelines for hydraulic structures design, 

and in assessing “best-management practices” for small 

watersheds. An interoccurrence interval is the expected 

or mean interval of time between precipitation “events,” 

in which an event occurs when the daily precipitation 

depth equals or exceeds a specified threshold (for example, 1 inch). Another application for interoccurrence 

intervals is for estimation of typical antecedent moisture 

conditions for a watershed. Antecedent moisture—that 

is, soil moisture prior to a runoff event—is semi-dependent on how often precipitation occurs. Reliable estimates of typical antecedent moisture conditions across 

the State could enhance the estimation of rainfall-runoff 

relations.

Beginning in 2002, the U.S. Geological Survey, in 

cooperation with the Texas Department of Transportation, began a study of the interoccurrence intervals for 

selected thresholds of daily precipitation in Texas. The 

purposes of this report are to provide (1) site-specific 

estimates of interoccurrence intervals, (2) maps showing the statewide distribution of the expected (average 

or mean) interoccurrence intervals for selected event 

thresholds, (3) adjustment factors to account for the 

calendar variation of precipitation potential, and 

(4) example applications of interoccurrence intervals. 

The thresholds selected for this report are 0.05, 0.10, 

0.25, 0.50, 0.75, 1.0, 1.5, 2.0, 2.5, and 3.0 inches.

Data Sources

A database of daily precipitation in Texas was 

aggregated using National Weather Service (NWS) precipitation data. The time series of daily precipitation 

database was assembled for this report using Hydrosphere (2002). Specifically, the Hydrosphere (2002) 

data are derived from the data archives of the National 

Climatic Data Center. For this report, the daily NWS 

precipitation stations considered included only those 

stations in Texas for which a station name, latitude, and 

longitude were available. In total 1,306 stations were 

considered. The total number of days of record represented by the 1,306 stations is in excess of 15.1 million. 

The earliest year of record is 1895 and the latest year 

of record is 2001. The average period of record for the 

stations is about 34 years, and about 660 stations were 

active as of 2001. The stations are listed in table 1 (at 
2 Atlas of Interoccurrence Intervals for Selected Thresholds of Daily Precipitation in Texas 

end of report); the table contains entries for NWS 

station name, NWS station number, latitude, longitude, 

and ancillary data. The stations are listed in alphabetical 

order and not numerical order of station number. To 

assist readers in referencing particular stations, an 

alphabetical ordering of Texas county names and the 

corresponding sequence numbers of stations within 

each county is listed in table 2 (at end of report). Finally, 

a map showing the locations of the 1,306 stations is 

shown in figure 1, and an example time series of a subset of the data for the Austin Camp Mabry station is 

shown in figure 2.

Previous Studies

Recent studies of precipitation characteristics in 

Texas pertinent to hydrologic design include Asquith 

(1998, 1999) and Asquith and Famiglietti (2000). 

Asquith (1998) presents procedures to estimate the 

depth-duration frequency of precipitation in Texas; for 

example, depth of the 6-hour 25-year precipitation. The 

procedures of Asquith (1998) are based on annual precipitation maxima and therefore are applicable only for 

the precipitation recurrence intervals of at least 365 

days (1 year). The procedures described in this report 

can be used for intervals of less than 1 year such as for 

0 25 50 75 100 MILES

0 50 100 150 200 KILOMETERS

Base modified from U.S. Geological Survey digital data

1:250,000, 2003

Albers-Equal Area projection

Standard parallels 29 ̊30’ and 45 ̊30’, central meridian -96 ̊

30o

106o

104o

98o 36o

34o

28o

26o

96o 94o

EXPLANATION

National Weather Service daily precipitation station

Figure 1. Locations of 1,306 National Weather Service daily precipitation stations in Texas.
APPROACH 3

the estimation of the 6-month depth of daily precipitation. This report compliments Asquith (1998). Asquith 

(1999) and Asquith and Famiglietti (2000) present 

precipitation areal-reduction factors associated with the 

1-day design storm for areas surrounding the cities of 

Austin, Dallas, Fort Worth, and Houston.

Bomar (1995, p. 60–63, figs. 30–33) provides the 

average number of days during each of the four seasons 

(winter, spring, summer, and fall) for daily precipitation 

thresholds of 0.01, 0.1, 0.5, and 1.0 inches. Although 

little content relevant to interoccurrence intervals is provided, Bomar (1995) contains much general information regarding precipitation characteristics and other 

meteorological topics for Texas. 

APPROACH

A Poisson process model is used in this report to 

define the distribution of interoccurence intervals for 

selected thresholds of daily precipitation. According to 

Clarke (1998, p. 111), “The Poisson process forms the 

starting-point for many applications in the water sciences [including the study of precipitation] in which 

probabilistic models are used to describe events occurring irregularly in time or space.” When an assumption 

is made that precipitation events are random variables 

with characteristics of a Poisson process, then straightforward statistical methods can be used to model the 

occurrence of precipitation events defined by a given 

threshold. A major component of a Poisson process is 

the mean interoccurrence interval—if the mean interoccurrence interval for a given location is known, then 

the Poisson process is specified. Further information 

regarding Poisson processes and related statistical topics are discussed in Ross (1994, p. 157–167), Wilks 

(1995, p. 71–73), Clarke (1998), and Bhat and Miller 

(2002).

Two steps are used in this report for characterizing and regionalizing interoccurrence intervals in 

Texas. The first step is to develop estimates of the 

interoccurrence intervals for each station. Such estimates are referred to as site-specific interoccurrence 

intervals. The second step is to regionalize the sitespecific estimates by mapping through spatial and geostatistical analysis so that reliable predictions of the 

interoccurrence intervals for selected precipitation 

thresholds can be made for any location in Texas.

Site-Specific Interoccurrence Intervals

The interoccurrence intervals of daily precipitation events that equal or exceed a given threshold for a 

given station are site-specific estimates and are determined directly from the daily precipitation database.

# Subset of daily precipitation time

# series for station Austin Camp Mabry

# ID = Station no.

# ST = State

# MMDDYYYY = Date

# DEPTH = Depth in inches

# CODE = T (Trace)

ID,ST,MMDDYYYY,DEPTH,CODE

428,TX,05171981,0.00, 

428,TX,05181981,0.10, 

428,TX,05191981,0.00, 

428,TX,05201981,0.00, 

428,TX,05211981,0.00, 

428,TX,05221981,0.00,T

428,TX,05231981,0.84, 

428,TX,05241981,3.88, 

428,TX,05251981,0.06, 

428,TX,05261981,0.00, 

428,TX,05271981,0.00,T

428,TX,05281981,0.00, 

428,TX,05291981,0.22, 

428,TX,05301981,1.38, 

428,TX,05311981,0.00, 

428,TX,06011981,0.62, 

428,TX,06021981,0.26, 

428,TX,06031981,0.55, 

428,TX,06041981,0.06, 

428,TX,06051981,0.16, 

428,TX,06061981,0.00, 

428,TX,06071981,0.00, 

428,TX,06081981,0.00, 

428,TX,06091981,0.00, 

428,TX,06101981,0.03, 

428,TX,06111981,5.66, 

428,TX,06121981,0.21, 

428,TX,06131981,4.50, 

Figure 2. Example of abbreviated time series of daily 

precipitation for station 428 Austin Camp Mabry.
4 Atlas of Interoccurrence Intervals for Selected Thresholds of Daily Precipitation in Texas 

For a Poisson process, the random variables 

 represent the interoccurrence intervals of 

the events, and the interoccurrence intervals are independent and identically distributed. The exponential 

distribution (Ross, 1994, p. 223–230; Evans and others, 

2000, p. 77–81; Bhat and Miller, 2002, p. 203) describes 

the cumulative distribution of the interoccurrence intervals of a Poisson process. The distribution in the context 

of interoccurrence intervals is given by

 for and (1)

where is the cumulative or nonexceedance probability for the observation that is less than or equal 

to some interoccurrence interval . The parameter 

is known as the arrival rate (of an event, in units of 

days-1), the arrival parameter, or the Poisson parameter. 

The value is the expected or mean interoccurrence interval ( ) with units of days (per event). In 

this report, interoccurrence interval is preferred over 

arrival rate, as it has units of days rather than the 

abstract units of days-1. The variance of the distribution 

is . For a homogeneous Poisson process, is 

constant. If varies, then the Poisson process is said to 

be nonhomogeneous.

The mean interoccurrence interval is computed as 

the mean interval between successive daily precipitation events that equal or exceed a given threshold. Thus, 

it follows that

. (2)

To indicate whether the daily occurrence of precipitation that equals or exceeds a given threshold likely 

follows a homogeneous Poisson process, hypothesis 

testing is required. For hypothesis testing Bhat and 

Miller (2002, p. 254–255) conclude that the standard 

normal variate, , for a Poisson process is

, and (3)

 for , (4)

where is the cumulative time, in days, for each event 

during the interval [ , ]. The statistic is hereinafter 

referred to as “sigma S.”

The cumulative probability of is used 

to estimate the p-value (Helsel and Hirsch, 1992, 

p. 97–116) or attained significance level of the data 

. The null hypothesis is that the interoccurrence intervals follow a homogeneous Poisson 

process. Large absolute values of indicate that the 

process probably is not a (homogeneous) Poisson 

process with a constant interoccurrence interval. The 

nonhomogeneous Poisson process for the daily precipitation occurrences is a possible alternative. Bhat and 

Miller (2002) do not discuss the “power” of a hypothesis test based on equation 3; hence, the potential for the 

so-called type II error (the Poisson model is incorrect 

but the model is accepted) of the test on the analysis in 

this report is unknown.

To demonstrate how the above equations are 

applied, consider the data set shown at the top of figure 3. The data set of daily precipitation comprises 20 

days ( = 20). For a threshold of 1 inch, there are two 

events ( = 2). Therefore, the mean interoccurrence 

interval is 10 days (20/2), the arrival rate is 0.10 (2/20), 

and the p-value is .357 or 35.7 percent. This p-value is 

not small—it is greater than a few percent or so—which 

indicates little statistical evidence that the data should 

not be modeled as a homogeneous Poisson process. 

Thus a reasonable conclusion is that the interoccurrence 

intervals of the example data follow a homogeneous 

Poisson process. For this report p-values greater than 

I1 I , , 2 ...

F In ( ) ≤ x 1 e

–λx = – x ≥ 0 n = 1 2, , ...

F

In

x λ

1 ⁄ λ

Λ

1 λ2 ⁄ λ

λ

λ n

T

-- no. of events above threshold

total time observed in days ---------------------------------------------------------------------- 1Λ == = ---

Z

Z

S nT

2 – ------

nT2

12 --------

= ---------------

S ti

i = 1

n

= ∑ 0 t1 t2 ... tn <<< << T

ti

0 T S

FZ Z

1 Fz ( ) – = P

Z

T

n

T = 20

n = 2

Λ = 10 days/event (20/2) — eq. 2

λ = 0.10 event/day (1/10) — eq. 2

S = t

1 + t2 = 8 + 15 = 23 — eq. 4

Z = (23 - 2 x 20/2)/(2 x 202/12)0.5 — eq. 3

Z = 0.3674 — eq. 3

FZ = 0.643 standard Normal table (Evans

 and others, 2000, p. 211)

p-value = 1 - .643 = .357

0, 0, 0, 0, 0, 0, 0, 1.1,

0, 0, 0, 0, 0, 0, 2.4, 0,

0 , 0 , 0 , 0 (Data Set)

Figure 3. Example interoccurrence interval 

computations for a hypothetical data set.
APPROACH 5

.01 provide sufficient evidence to conclude that the data 

follow a homogeneous Poisson process. 

Similar computations to those illustrated in figure 

3 for each of the selected depth thresholds (0.05, 0.10, 

0.25, 0.50, 0.75, 1.0, 1.5, 2.0, 2.5, and 3.0 inches) and 

for each of the 1,306 daily precipitation stations were 

done. The computations provide the basis for subsequent analyses presented here. The computational 

results for each depth threshold are listed in tables 3–7 

(at end of report).

The tables identify each station by the sequence 

number shown in table 1. For each station, the mean 

interoccurrence interval is reported along with the total 

number of events for the indicated threshold within the 

entire period of record for the station and the total number of days available. The sigma S, standard normal 

variate, and nonexceedance probability of the standard 

normal variate provide the basis for the testing of a 

homogeneous Poisson process. Finally, the p-value 

corresponding to the nonexceedance probability is 

reported.

Another important feature of a Poisson process is 

the distribution of the number of events, , occurring 

during a given interval [0, ]. The probability density 

function of the Poisson process (Ross, 1994, 

p. 157; Bhat and Miller, 2002, p. 202) is 

. (5)

The cumulative distribution function of 

the Poisson process is

. (6)

For example, suppose the mean interoccurrence 

interval is days ( ). To the closest 

integer, what is the median number of occurrences 

( , or a 50-percent probability) in a -

day period? From equations 5 and 6, the probabilities of 

the Poisson process are computed, and the computations 

are summarized in table 8 (at end of report). The median 

number of occurrences for the example is five.

Regionalization of Interoccurrence Intervals

Regionalization in this report is a two-step 

process. First, a spatial analysis or “neighborhood 

smoothing” of the interoccurrence intervals is done for 

each selected daily precipitation threshold for all stations. Second, geostatistical analysis is done on the 

smoothed interoccurrence intervals to produce a continuously varying map of interoccurrence intervals for 

each selected daily precipitation threshold. The maps 

can be used to estimate the interoccurrence interval for 

any location in Texas.

Neighborhood smoothing is the process by which 

the interoccurrence intervals for a particular station and 

those surrounding it are combined or “pooled” together 

to develop a more reliable estimate of the interoccurrence interval for the location of the station than can be 

derived from the data for the station alone. In other 

words, the neighborhood of stations surrounding a 

particular station contains more information—more 

days of record—about the characteristics of precipitation occurrence in that area than is available at the particular station. 

The neighborhood smoothing for each station ( ) 

consisted of computing the “smoothed” mean interoccurrence interval through a weighted average of the 

station interval and the four nearest station intervals. 

Record length, as measured by the total number of 

days, provided the weights. Stations for which the 

p-value of the mean interoccurrence interval was less 

than or equal to .01 were not used in the weightedaverage computations. For example, if p-values for two 

of the five stations (four neighbors plus the th station) 

were less than or equal to .01, then only three stations 

were used in the averaging. The benefit of using stations 

with p-values greater than .01 is that stations for which 

interoccurrence intervals do not (with 99-percent or 

greater probability) follow a homogenous Poisson process are objectively removed from analysis. The critical 

p-value of .01 was arbitrarily chosen. This significance 

level eliminates about 3 to 14 percent of the stations for 

depth thresholds of 0.25 inch and larger. Considering 

the large database used, eliminating these stations 

enhances the reliability of interoccurrence interval estimates for a homogenous Poisson model.

The regionalization of interoccurrence intervals included geostatistically based mapping of the 

smoothed values using the method of kriging (Isaaks 

and Srivastava, 1989). The kriging was performed using 

a Gaussian model of the semivariogram with a range of 

1,212,900 meters and a nugget that ranged from 1.59 

days squared to 792,490 days squared for the 0.05- and 

3.0-inch thresholds, respectively. The neighborhood for 

the kriging operation used a minimum of two stations 

n

T

fn( ) T

fn( ) T e

–λT( ) λT n

n! ------------- e

–T ⁄ Λ( ) T ⁄ Λ n

n! = = ------------------

Fn( ) T

Fn( ) T e

–λT ( ) λT i

i! ------------

i = 0

n

∑ e

–T ⁄ Λ ( ) T ⁄ Λ i

i! -----------------

i = 0

n

= = ∑

Λ = 10 λ = 0.1

F = 0.5 T = 60

m

i

i
6 Atlas of Interoccurrence Intervals for Selected Thresholds of Daily Precipitation in Texas 

and a maximum of 13 stations in conjunction with a circular search method.

Initial interoccurrence interval maps were computer generated, and the resulting lines of equal interval 

overlain on the mapped values for the smoothed intervals. The computer-generated lines of equal interval 

were then manually smoothed and variable intervals 

retained to assist in interpolation near the boundaries 

of Texas. The smoothed lines of equal interval subsequently were overlain on the mapped site-specific 

interoccurrence intervals (point values), and visual 

confirmation of the lines was made. Finally, diagnostic 

statistics of the maps, which are presented in the section 

“Statewide Interoccurrence Interval Maps,” were 

computed.

INTEROCCURRENCE INTERVALS FOR 

SELECTED DAILY PRECIPITATION 

THRESHOLDS IN TEXAS

Statewide Interoccurrence Interval Maps

Maps depicting the spatial variability of the 

interoccurrence interval for the 10 selected daily precipitation thresholds in Texas are shown in figures 4–13. 

Specific geographic locations are referred to in this 

report; the locations are identified only in figure 4. 

Tick marks of latitude and longitude in increments of 

2 degrees are provided to facilitate adapting the maps 

for digital representation. On all the maps, a general 

pattern of increasing interoccurrence interval toward 

the western parts of the State is observed. The contours 

in the eastern one-half of the State have a pronounced 

north-south direction. These two characteristics of 

the maps are consistent with the patterns of mean 

annual precipitation in Texas. Mean annual precipitation in Texas decreases east to west and is relatively 

constant with north-south direction (Bomar, 1995).

The accuracy of the maps west of the Pecos 

River is less relative to the accuracy east of the Pecos 

River for reasons discussed in the section “Influence of 

Elevation on Interoccurrence Intervals West of the 

Pecos River.”

Other observations are applicable to all the maps 

(figs. 4–13). One observation is that interoccurrence 

intervals in the Hill Country (fig. 4) generally are 

smaller than intervals in the same longitude range in the 

rest of the State. Another observation is that the lines of 

equal interval are approximately perpendicular to the 

coastline of the Gulf of Mexico. For each of these two 

observations the line patterns are similar to those of 

Asquith (1998, figs. 10–23). Details and observations 

about selected maps follow.

On the map depicting the interoccurrence interval 

for a 0.05-inch and greater daily precipitation threshold 

(fig. 4), interoccurrence interval decreases substantially 

in the Davis Mountains. Reliable intervals for the 

Guadalupe and Chisos Mountains are problematic. Precipitation potential generally increases (smaller interoccurrence intervals) over large mountains because of the 

orographic effect.

On the map depicting the interoccurrence interval 

for a 0.10-inch and greater daily precipitation threshold 

(fig. 5), interoccurrence interval decreases substantially 

in the Chisos, Davis, and Guadalupe Mountains. Reliable intervals for all three mountain ranges are difficult 

to develop. Decreases in interoccurrence intervals associated with the mountains also are characteristic of other 

daily precipitation thresholds.

For the map depicting the interoccurrence interval for a 0.25-inch and greater daily precipitation 

threshold (fig. 6), the 7.5-day line of equal interval just 

outside the northeastern corner of Texas was added to 

constrain interpolation.

For the map depicting the interoccurrence interval 

for a 0.50-inch and greater daily precipitation threshold (fig. 7), the 33-day line of equal interval in the 

northwestern corner of Texas was added to constrain 

interpolation.

For the map depicting the interoccurrence interval for a 0.75-inch and greater daily precipitation 

threshold (fig. 8), the 58-day line of equal interval in 

the northwestern corner of Texas was added to constrain 

interpolation.

A summary of statewide interoccurrence interval 

statistics and diagnostic statistics of the maps in figures 

4–13 is listed in table 9 (at end of report). The statistics 

in columns 2 and 3 were computed using the interoccurrence interval for all available stations.

As the threshold increases, mean interoccurrence 

interval increases (table 9). The standard deviation of 

the interoccurrence intervals increases much more rapidly than the mean; this indicates a larger variation, 

change, or range in the interoccurrence interval across 

the State as the threshold increases.

A total of 1,306 stations are considered in this 

report; not all of these stations are available for 

the production of each threshold map because of 

removal of stations based on the p-values described in 

the “Approach” section. Also, the statewide number of 
INTEROCCURRENCE INTERVALS FOR SELECTED DAILY PRECIPITATION THRESHOLDS IN TEXAS 7

stations with events for a given threshold decreases 

with increasing threshold. For example, there are only 

seven stations with no daily rainfall values greater than 

0.05 inch (1,306 – 1,299 = 7), but there are 163 stations with no daily rainfall greater than 3.0 inches 

(1,306 – 1,143 = 163).

The number of p-values less than or equal to .01 

decreases substantially as the threshold increases. This 

indicates that as rainfall events are increasingly less frequent, a homogeneous Poisson model of the rainfall 

occurrence is increasingly more appropriate. This 

observation is expected because of the natural tendency 

for a rainy day to be followed by another rainy day—as 

the threshold becomes progressively smaller, progressively more events are likely to occur on consecutive 

days. The number of p-values less than or equal to .01 

for the 0.05- and 0.10-inch thresholds are large enough 

that general applicability of a homogeneous Poisson 

model for these thresholds is questionable. For comparison, about 270 stations have p-values less than or equal 

to .001 for the 0.05-inch threshold, compared to 406 stations with p-values less than or equal to .01 (table 9). 

Two simple diagnostic statistics of the interoccurrence interval maps are reported in table 9. The 

0 25 50 75 100 MILES

0 50 100 150 200 KILOMETERS

Pecos River

GULF OF MEXICO

Base modified from U.S. Geological Survey digital data

1:250,000, 2003

Albers-Equal Area projection

Standard parallels 29 ̊30’ and 45 ̊30’, central meridian -96 ̊

EXPLANATION

Line of equal interoccurrence interval

in days—Interval variable

10

7.5

9

8

10

8

12

13 11

6

5.5

5

4.5

5

11

10

12

14

13

7

15

9

9

GUADALUPE

MOUNTAINS

DAVIS

MOUNTAINS

CHISOS

MOUNTAINS

HILL

COUNTRY

Austin

Lubbock

30o

106o

104o

98o 36o

34o

28o

26o

96o 94o

Figure 4. Interoccurrence interval for a 0.05-inch and greater daily precipitation threshold for Texas.
8 Atlas of Interoccurrence Intervals for Selected Thresholds of Daily Precipitation in Texas 

statistics are the mean bias and the root-mean-square 

error (RMSE) of the interoccurrence interval map. The 

bias at the th station, “station bias,” is computed by 

subtracting the site-specific interoccurrence interval at 

the station from the interval extracted from the map. 

The mean bias is the arithmetic average of the station 

biases for each threshold. The mean bias should be 

about zero for each map. The mean bias is a simple 

check on whether the geostatistical analysis and contouring functioned appropriately. 

The RMSE error of a map is a more important 

diagnostic. The RMSE for each threshold is defined as

, (7)

where 

is the site-specific interoccurrence interval, in days; 

is the mapped interoccurrence interval, in days; and

is the number of stations with site-specific 

interoccurrence intervals for a given threshold. 

i RMSE 1

n

-- Ii Mi ( ) – 2

i = 1

n

= ∑

Ii

Mi

n

0 25 50 75 100 MILES

0 50 100 150 200 KILOMETERS

GULF OF MEXICO

Base modified from U.S. Geological Survey digital data

1:250,000, 2003

Albers-Equal Area projection

Standard parallels 29 ̊30’ and 45 ̊30’, central meridian -96 ̊

EXPLANATION

Line of equal interoccurrence interval

in days—Interval variable

10

30o

106o

104o

98o 36o

34o

28o

26o

96o 94o

11

9.5

9.25

18

16

14

12

11

10

12

14

16

17

15.5

12

11

10

9

8

7

14

6

5.5

5.75

5.25

9.5

17

5.5

Figure 5. Interoccurrence interval for a 0.10-inch and greater daily precipitation threshold for Texas.
INTEROCCURRENCE INTERVALS FOR SELECTED DAILY PRECIPITATION THRESHOLDS IN TEXAS 9

The number of stations with events and hence an 

available site-specific interoccurrence interval differs 

for each threshold. The RMSE reflects how well the 

lines of equal interval match the site-specific intervals. 

The percent change from the statewide standard deviation of the interoccurrence intervals to the RMSE ranges 

from a magnitude minimum of (negative) -24 to a magnitude maximum of -60 percent for the 0.05- and 2.0-

inch thresholds, respectively. Because of the substantial 

negative percent change, the maps are considered more 

reliable estimators of the mean interoccurrence interval 

for most locations in Texas than the statewide mean 

value.

Influence of Elevation on Interoccurrence 

Intervals West of the Pecos River

Because of the orographic influence of elevation 

on precipitation potential in mountainous regions, an 

assessment of the relation between interoccurrence 

interval and elevation west of the Pecos River (fig. 4) is 

informative. For each of the stations west of the Pecos 

River, the site-specific mean interoccurrence interval 

for each threshold is graphed with the corresponding 

elevation of the station in figure 14. All stations are represented on the figure without regard to p-value. The 

interoccurrence interval decreases with elevation up 

0 25 50 75 100 MILES

0 50 100 150 200 KILOMETERS

GULF OF MEXICO

Base modified from U.S. Geological Survey digital data

1:250,000, 2003

Albers-Equal Area projection

Standard parallels 29 ̊30’ and 45 ̊30’, central meridian -96 ̊

EXPLANATION

Line of equal interoccurrence interval

in days—Interval variable

10

30o

106o

104o

98o 36o

34o

28o

26o

96o 94o

24

24 28

35

28

20

16

20

18

16

14

11

12

10

8

7.25

7.5

9

Figure 6. Interoccurrence interval for a 0.25-inch and greater daily precipitation threshold for Texas.
10 Atlas of Interoccurrence Intervals for Selected Thresholds of Daily Precipitation in Texas 

to about the 1.0-inch threshold. For thresholds larger 

than 1.0 inch, little or no relation between the interoccurrence interval and elevation is evident for reasons 

that are not apparent to the authors. However, it is probable and expected that the interoccurrence intervals 

are relatively smaller for the highest stations (those 

above 5,000 feet). Because of the influence of elevation, 

the contours of interoccurrence intervals west of the 

Pecos River—specifically in and west of the Chisos, 

Guadalupe, and Davis Mountains (fig. 4)—are less 

reliable. The reliability of the lines of equal interval 

diminishes also with increasing threshold because the 

interoccurrence intervals become very large relative to 

the typical record lengths at the stations west of the 

Pecos River. Furthermore, many of those stations have 

no recorded events for the largest thresholds. This is 

evident in the fewer number of points plotted in figure 

14j compared to figure 14a–f. Concerns over the reliability of interoccurrence interval contours in far west 

Texas is a partial motivation for including the sitespecific interoccurrence intervals in tables 3–7. Readers 

can choose to investigate specific locations in greater 

detail.

0 25 50 75 100 MILES

0 50 100 150 200 KILOMETERS

GULF OF MEXICO

Base modified from U.S. Geological Survey digital data

1:250,000, 2003

Albers-Equal Area projection

Standard parallels 29 ̊30’ and 45 ̊30’, central meridian -96 ̊

EXPLANATION

Line of equal interoccurrence interval

in days—Interval variable

11

30o

106o

104o

98o 36o

34o

28o

26o

96o 94o

80

66

48

32

40

48

40

60

33

33

32

34

28

24

20

18

16

14

12

11

11.5

10.5

Figure 7. Interoccurrence interval for a 0.50-inch and greater daily precipitation threshold for Texas.
INTEROCCURRENCE INTERVALS FOR SELECTED DAILY PRECIPITATION THRESHOLDS IN TEXAS 11

Intra-Annual Variations in Interoccurrence 

Intervals

The interoccurrence interval maps presented in 

the previous section generally are reliable estimators of 

the parameter for a homogeneous Poisson model of 

daily precipitation for a given threshold. However, precipitation characteristics in Texas vary seasonally (see 

Bomar, 1995). The intra-annual variation documented 

in this section is derived by grouping the data for the 

entire State. Geographic or spatial differences in intraannual variations of interoccurrence intervals are not 

represented, although differences likely exist in a region 

as large as Texas.

Summaries of the intra-annual variability of precipitation occurrence for each of the 10 thresholds are 

listed in tables 10–19 (at end of report). Complementing 

the tables are boxplots showing the distribution of 

interoccurrence ratios for each month in figures 15–24. 

The intra-annual variability is reflected in a mean 

“interoccurrence ratio” for each month. The individual 

monthly ratios are computed by dividing each interoccurrence interval by the mean interoccurrence interval 

for the station. Sample sizes are shown in figures 15–24; 

0 25 50 75 100 MILES

0 50 100 150 200 KILOMETERS

GULF OF MEXICO

Base modified from U.S. Geological Survey digital data

1:250,000, 2003

Albers-Equal Area projection

Standard parallels 29 ̊30’ and 45 ̊30’, central meridian -96 ̊

EXPLANATION

Line of equal interoccurrence interval

in days—Interval variable

15

30o

106o

104o

98o 36o

34o

28o

26o

96o 94o

16

18

15

16

21

24

27

30

35

40

50

70

90

80

90

80

70

110

150

58

166

100

48

Figure 8. Interoccurrence interval for a 0.75-inch and greater daily precipitation threshold for Texas.
12 Atlas of Interoccurrence Intervals for Selected Thresholds of Daily Precipitation in Texas 

however, the sample sizes do not match the “Statewide 

no. of stations with events” column in table 9 because 

not all stations have an event in all months. The mean 

monthly interoccurrence ratio (column 2) is computed 

as the average of all the individual monthly ratios for all 

the stations; likewise, the median monthly ratio (column 

3) is the median of all the monthly ratios for all the stations. 

Interpretation of the ratios is as follows: When the 

ratio is greater than unity for a given month, the events 

occurring in that month are less frequent (less likely, 

longer interval) than the mean interoccurrence interval. 

Likewise, when the ratio is less than unity, the events are 

more frequent (more likely, shorter interval) than the 

mean interoccurrence interval.

Finally, for each sequence of mean and median 

monthly ratios an “adjusted ratio” (columns 4 and 5) 

was computed with an adjustment or offset to ensure 

that the arithmetic average of all 12 ratios is unity. The 

adjusted ratios are preferable because the arithmetic 

average of each of the adjusted ratios multiplied by a 

specific mean interoccurrence interval recovers the 

mean interoccurrence interval. Bias is mitigated.

0 25 50 75 100 MILES

0 50 100 150 200 KILOMETERS

GULF OF MEXICO

Base modified from U.S. Geological Survey digital data

1:250,000, 2003

Albers-Equal Area projection

Standard parallels 29 ̊30’ and 45 ̊30’, central meridian -96 ̊

EXPLANATION

Line of equal interoccurrence interval

in days—Interval variable

52

30o

106o

104o

98o 36o

34o

28o

26o

96o 94o

52

24

44

335

20

28

24

60

80

100

100

125

150

125

250

200

200

32

36

Figure 9. Interoccurrence interval for a 1.0-inch and greater daily precipitation threshold for Texas.
INTEROCCURRENCE INTERVALS FOR SELECTED DAILY PRECIPITATION THRESHOLDS IN TEXAS 13

It is informative to graphically illustrate the 

adjusted interoccurrence ratios listed in tables 10–19. 

The relation between month and the mean and median 

adjusted interoccurrence ratios from tables 10 and 11 

for the 0.05- and 0.10-inch thresholds are graphed in 

figure 25. The graph shows two distinct troughs in the 

mean and median ratios. The first trough occurs in May 

and June and the second in September. The troughs 

indicate smaller interoccurrence intervals between rainfall events defined by the threshold—months in the 

rainy seasons. The change in the mean monthly interoccurrence ratio from April to May (from about 1.07 to 

about 0.79) is substantial. To clarify, the April interoccurrence interval is about 107 percent of the mean 

interoccurrence interval for a location; whereas the May 

interoccurrence interval is about 79 percent of the mean 

interoccurrence interval for a location.

The relations between month and adjusted mean 

interoccurrence ratio for the 0.25-, 0.50-, 0.75-, 1.0-, 

1.5-, 2.0-, 2.5-, and 3.0-inch thresholds (tables 12–19) 

are shown in figure 26, and the relations between 

month and adjusted median interoccurrence ratio are 

0 25 50 75 100 MILES

0 50 100 150 200 KILOMETERS

GULF OF MEXICO

Base modified from U.S. Geological Survey digital data

1:250,000, 2003

Albers-Equal Area projection

Standard parallels 29 ̊30’ and 45 ̊30’, central meridian -96 ̊

EXPLANATION

Line of equal interoccurrence interval

in days—Interval variable

550

30o

106o

104o

98o 36o

34o

28o

26o

96o 94o

80

50

975

125

40

250

275

350

275

550

750

95

100

150

550

750

200

70

60

40

Figure 10. Interoccurrence interval for a 1.5-inch and greater daily precipitation threshold for Texas.
14 Atlas of Interoccurrence Intervals for Selected Thresholds of Daily Precipitation in Texas 

shown in figure 27. The ratios in each figure mimic 

the trends established in figure 25 for the 0.05- and 

0.10-inch thresholds. However, some distinctive 

differences are visible. One trough is visible between 

about May–July, and another trough is visible in September and October. For thresholds less than about 1.0 

inch the May–July trough is deepest; for larger thresholds the ratios are closer to unity. The ratios peak in 

January–March for the 1.0-inch and less thresholds, 

but peak only in March for the larger thresholds. The 

graphs indicate that considerable and systematic 

intra-annual variations in the interoccurrence ratios 

exist.

EXAMPLE APPLICATIONS

The following examples illustrate the application 

of the site-specific and regional estimates of the interoccurrence intervals in this report. The underlying 

assumption for the applications illustrated in this section is that the occurrence of precipitation follows a 

Poisson process.

0 25 50 75 100 MILES

0 50 100 150 200 KILOMETERS

GULF OF MEXICO

Base modified from U.S. Geological Survey digital data

1:250,000, 2003

Albers-Equal Area projection

Standard parallels 29 ̊30’ and 45 ̊30’, central meridian -96 ̊

EXPLANATION

Line of equal interoccurrence interval

in days—Interval variable

150

30o

106o

104o

98o 36o

34o

28o

26o

96o 94o

60

90

90

110

500

250

150

1000

500

2000

2000

1000

2000

3000

4000

400

225

300

70

130

150

200

Figure 11. Interoccurrence interval for a 2.0-inch and greater daily precipitation threshold for Texas.
EXAMPLE APPLICATIONS 15

Site-Specific Median 6-Month Daily 

Precipitation Threshold

In hydrologic design practice, it is sometimes 

useful to set design criteria for occurrences of precipitation that happen at subannual intervals. For example, 

the median 6-month storm might be required for a 

design. The 6-month storm can be defined in terms of 

an interoccurrence interval. Specifically, consider the 

interoccurrence interval distribution from equation 1. 

Six months has a day length ( ) of 182.5 days (365/2), 

and the median interoccurrence has = 0.5. Substituting these values into equation 1 yields

, (8)

, and (9)

 days. (10)

Hence, the median 6-month daily precipitation has a 

x mean interoccurrence interval of about 263 days.

F

0.5 1 e

–182.5λ = –

λ = 0.003798

1 ⁄ Λ λ = = 263

0 25 50 75 100 MILES

0 50 100 150 200 KILOMETERS

GULF OF MEXICO

Base modified from U.S. Geological Survey digital data

1:250,000, 2003

Albers-Equal Area projection

Standard parallels 29 ̊30’ and 45 ̊30’, central meridian -96 ̊

EXPLANATION

Line of equal interoccurrence interval

in days—Interval variable

160

30o

106o

104o

98o 36o

34o

28o

26o

96o 94o

400

9000

120

160

1200

4000

180

4400

4400

2400

100

200

240

280

500

500

600

900

1200

1500

Figure 12. Interoccurrence interval for a 2.5-inch and greater daily precipitation threshold for Texas.
16 Atlas of Interoccurrence Intervals for Selected Thresholds of Daily Precipitation in Texas 

Now for a specific location, it is necessary to 

estimate the daily precipitation threshold for which the 

interoccurrence interval is 263 days. This is achieved 

using either site-specific information or regionalized 

estimates of the interoccurrence interval for a given 

location. For this example, site-specific information is 

used.

Consider the site-specific interoccurrence intervals for station 428 Austin Camp Mabry (sequence 

no. 46). This is a long-term station with about 72 years 

of record (table 1). The interoccurrence intervals 

from tables 4–7 for the selected thresholds are listed in 

figure 28. The interoccurrence intervals for daily precipitation thresholds of 0.05 and 0.10 inch (table 3) 

are not used. Also shown in figure 28 is the relation 

between the daily precipitation threshold and the mean 

interoccurrence interval; the relation is nearly linear on 

a semi-log scale. Superimposed on the figure is a dashed 

horizontal line for the mean interoccurrence interval 

of 263 days. The dashed line indicates that a precipitation threshold depth with an interoccurrence interval of 

263 days is about 2.56 inches. The site-specific median 

6-month daily precipitation for Austin Camp Mabry 

thus is equal to or greater than 2.56 inches.

0 25 50 75 100 MILES

0 50 100 150 200 KILOMETERS

GULF OF MEXICO

Base modified from U.S. Geological Survey digital data

1:250,000, 2003

Albers-Equal Area projection

Standard parallels 29 ̊30’ and 45 ̊30’, central meridian -96 ̊

EXPLANATION

Line of equal interoccurrence interval

in days—Interval variable

500

30o

106o

104o

98o 36o

34o

28o

26o

96o 94o

10000

5000

5000

3500

3000

2300

2500

1300

1000

700

300

600

500

400

300

200

160

Figure 13. Interoccurrence interval for a 3.0-inch and greater daily precipitation threshold for Texas.
EXAMPLE APPLICATIONS 17

ELEVATION, IN FEET ABOVE NGVD 29 ELEVATION, IN FEET ABOVE NGVD 29

1,000 2,000 2,000 4,000 6,000 6,000 7,000 1,000 4,000 7,000

0

2,000

4,000

6,000

8,000

10,000

12,000

0

5,000

10,000

15,000

20,000

25,000

30,000

0

10

20

30

40

50

60

70

80

0

500

1,000

1,500

2,000

2,250

0

100

200

300

400

425

0

20

40

60

80

100

120

140

0

10

20

30

40

50

60

70

80

0

100

200

300

400

450

0

200

400

600

800

925

0

2,000

4,000

6,000

8,500

8,000

MEAN INTEROCCURRENCE INTERVAL, IN DAYS

MEAN INTEROCCURRENCE INTERVAL, IN DAYS

(a) (b)

(c) (d)

(e)

(g)

(i) (j)

(f)

(h)

2.5-inch threshold 3.0-inch threshold

1.5-inch threshold 2.0-inch threshold

0.75-inch threshold 1.0-inch threshold

0.25-inch threshold 0.50-inch threshold

0.05-inch threshold 0.10-inch threshold

Figure 14. Relation between interoccurrence interval and elevation west of the Pecos River, west Texas.
18 Atlas of Interoccurrence Intervals for Selected Thresholds of Daily Precipitation in Texas 

(1,252)

EXPLANATION

Sample size

Data value greater than 3.0 times the IQR

outside the box

Data value 1.5 to 3.0 times the IQR

outside the box

Largest data value within 1.5 times the IQR

above the box

75th percentile

Mean

Median (50th percentile)

25th percentile

Smallest data value within 1.5 times the IQR

below the box

Interquartile range (IQR)

(1,251)

(1,251)

(1,253)

(1,255)

(1,252)

(1,256)

(1,258)

(1,239)

(1,259)

(1,245)

(1,229)

(1,245)

MONTH

J F MA MJ J A S O N D

INTEROCCURRENCE RATIO, DIMENSIONLESS

0

1

2

3

4

5

6

7

8

9

10

11

12

0

Figure 15. Distribution of ratio of interoccurrence interval for month to mean interoccurrence interval for period of 

record at station for a 0.05-inch and greater daily precipitation threshold for Texas.
EXAMPLE APPLICATIONS 19

(1,255)

EXPLANATION

Sample size

Data value greater than 3.0 times the IQR

outside the box

Data value 1.5 to 3.0 times the IQR

outside the box

Largest data value within 1.5 times the IQR

above the box

75th percentile

Mean

Median (50th percentile)

25th percentile

Smallest data value within 1.5 times the IQR

below the box

Interquartile range (IQR)

(1,250)

(1,249)

(1,250)

(1,255)

(1,250)

(1,256)

(1,256)

(1,234)

(1,258)

(1,241)

(1,222)

(1,242)

MONTH

J F MA MJ J A S O N D

INTEROCCURRENCE RATIO, DIMENSIONLESS

0

1

2

3

4

5

6

7

8

9

10

11

12

0

Figure 16. Distribution of ratio of interoccurrence interval for month to mean interoccurrence interval for period of 

record at station for a 0.10-inch and greater daily precipitation threshold for Texas.
20 Atlas of Interoccurrence Intervals for Selected Thresholds of Daily Precipitation in Texas 

Sample size

Data value greater than 3.0 times the IQR

outside the box

Data value 1.5 to 3.0 times the IQR

outside the box

Largest data value within 1.5 times the IQR

above the box

75th percentile

Mean

Median (50th percentile)

25th percentile

Smallest data value within 1.5 times the IQR

below the box

Interquartile range (IQR)

(1,205)

EXPLANATION

(1,242)

(1,232)

(1,234)

(1,253)

(1,249)

(1,250)

(1,251)

(1,225)

(1,250)

(1,235)

(1,205)

(1,221)

MONTH

J F MA MJ J A S O N D

INTEROCCURRENCE RATIO, DIMENSIONLESS

0

1

2

3

4

5

6

7

8

9

10

11

12

0

Figure 17. Distribution of ratio of interoccurrence interval for month to mean interoccurrence interval for period of 

record at station for a 0.25-inch and greater daily precipitation threshold for Texas.
EXAMPLE APPLICATIONS 21

Figure 18. Distribution of ratio of interoccurrence interval for month to mean interoccurrence interval for period of 

record at station for a 0.50-inch and greater daily precipitation threshold for Texas.

(1,229)

EXPLANATION

Sample size

Data value greater than 3.0 times the IQR

outside the box

Data value 1.5 to 3.0 times the IQR

outside the box

Largest data value within 1.5 times the IQR

above the box

75th percentile

Mean

Median (50th percentile)

25th percentile

Smallest data value within 1.5 times the IQR

below the box

Interquartile range (IQR)

(1,224)

(1,195)

(1,205)

(1,245)

(1,225)

(1,243)

(1,241)

(1,188)

(1,229) (1,225)

(1,178)

(1,183)

MONTH

J F MA MJ J A S O N D

INTEROCCURRENCE RATIO, DIMENSIONLESS

0

1

2

3

4

5

6

7

8

9

10

11

12

0
22 Atlas of Interoccurrence Intervals for Selected Thresholds of Daily Precipitation in Texas 

(1,207)

EXPLANATION

Sample size

Data value greater than 3.0 times the IQR

outside the box

Data value 1.5 to 3.0 times the IQR

outside the box

Largest data value within 1.5 times the IQR

above the box

75th percentile

Mean

Median (50th percentile)

25th percentile

Smallest data value within 1.5 times the IQR

below the box

Interquartile range (IQR)

(1,198) (1,126)

(1,159)

(1,231)

(1,206) (1,228)

(1,228)

(1,140)

(1,210) (1,207)

(1,138)

(1,141)

MONTH

J F MA MJ J A S O N D

INTEROCCURRENCE RATIO, DIMENSIONLESS

0

1

2

3

4

5

6

7

8

9

10

11

12

0

Figure 19. Distribution of ratio of interoccurrence interval for month to mean interoccurrence interval for period of 

record at station for a 0.75-inch and greater daily precipitation threshold for Texas.
EXAMPLE APPLICATIONS 23

(1,216)

EXPLANATION

(1,162)

(1,040)

(1,108)

(1,204)

(1,176)

(1,203)

(1,216)

(1,088)

(1,186)

(1,189)

(1,104)

(1,083)

MONTH

J F MA MJ J A S O N D

INTEROCCURRENCE RATIO, DIMENSIONLESS

0

1

2

3

4

5

6

7

8

9

10

11

12

0

Sample size

Data value greater than 3.0 times the IQR

outside the box

Data value 1.5 to 3.0 times the IQR

outside the box

Largest data value within 1.5 times the IQR

above the box

75th percentile

Mean

Median (50th percentile)

25th percentile

Smallest data value within 1.5 times the IQR

below the box

Interquartile range (IQR)

Figure 20. Distribution of ratio of interoccurrence interval for month to mean interoccurrence interval for period of 

record at station for a 1.0-inch and greater daily precipitation threshold for Texas.
24 Atlas of Interoccurrence Intervals for Selected Thresholds of Daily Precipitation in Texas 

(1,129)

EXPLANATION

(1,085)

(880)

(953)

(1,154)

(1,086)

(1,150)

(1,154)

(972)

(1,123)

(1,129)

(990)

(943)

MONTH

J F MA MJ J A S O N D

INTEROCCURRENCE RATIO, DIMENSIONLESS

0

1

2

3

4

5

6

7

8

9

10

11

12

0

Sample size

Data value greater than 3.0 times the IQR

outside the box

Data value 1.5 to 3.0 times the IQR

outside the box

Largest data value within 1.5 times the IQR

above the box

75th percentile

Mean

Median (50th percentile)

25th percentile

Smallest data value within 1.5 times the IQR

below the box

Interquartile range (IQR)

Figure 21. Distribution of ratio of interoccurrence interval for month to mean interoccurrence interval for period of 

record at station for a 1.5-inch and greater daily precipitation threshold for Texas.
EXAMPLE APPLICATIONS 25

(1,073)

EXPLANATION

Sample size

Data value greater than 3.0 times the IQR

outside the box

Data value 1.5 to 3.0 times the IQR

outside the box

Largest data value within 1.5 times the IQR

above the box

75th percentile

Mean

Median (50th percentile)

25th percentile

Smallest data value within 1.5 times the IQR

below the box

Interquartile range (IQR)

(969)

(691)

(798)

(1,073)

(990)

(1,066)

(1,089)

(826)

(1,033)

(1,061)

(866)

(775)

MONTH

J F MA MJ J A S O N D

INTEROCCURRENCE RATIO, DIMENSIONLESS

0

1

2

3

4

5

6

7

8

9

10

11

12

0

Figure 22. Distribution of ratio of interoccurrence interval for month to mean interoccurrence interval for period of 

record at station for a 2.0-inch and greater daily precipitation threshold for Texas.
26 Atlas of Interoccurrence Intervals for Selected Thresholds of Daily Precipitation in Texas 

Sample size

Data value greater than 3.0 times the IQR

outside the box

Data value 1.5 to 3.0 times the IQR

outside the box

Largest data value within 1.5 times the IQR

above the box

75th percentile

Mean

Median (50th percentile)

25th percentile

Smallest data value within 1.5 times the IQR

below the box

Interquartile range (IQR)

(813)

EXPLANATION

(813) (497)

(627)

(980)

(866)

(978)

(976)

(662)

(921)

(971)

(702)

(630)

MONTH

J F MA MJ J A S O N D

INTEROCCURRENCE RATIO, DIMENSIONLESS

0

1

2

3

4

5

6

7

8

9

10

11

12

0

Figure 23. Distribution of ratio of interoccurrence interval for month to mean interoccurrence interval for period of 

record at station for a 2.5-inch and greater daily precipitation threshold for Texas.
EXAMPLE APPLICATIONS 27

(522)

EXPLANATION

Sample size

Data value greater than 3.0 times the IQR

outside the box

Data value 1.5 to 3.0 times the IQR

outside the box

Largest data value within 1.5 times the IQR

above the box

75th percentile

Mean

Median (50th percentile)

25th percentile

Smallest data value within 1.5 times the IQR

below the box

Interquartile range (IQR)

(699)

(374)

(430)

(894)

(739)

(865) (906)

(497)

(803)

(908)

(577)

(522)

MONTH

J F MA MJ J A S O N D

INTEROCCURRENCE RATIO, DIMENSIONLESS

0

1

2

3

4

5

6

7

8

9

10

11

12

0

Figure 24. Distribution of ratio of interoccurrence interval for month to mean interoccurrence interval for period of 

record at station for a 3.0-inch and greater daily precipitation threshold for Texas.
28 Atlas of Interoccurrence Intervals for Selected Thresholds of Daily Precipitation in Texas 

Less frequent precipitation for a given threshold

More frequent precipitation for a given threshold

EXPLANATION

Adjusted mean interoccurrence ratio for 0.05-inch and greater precipitation threshold 

Adjusted mean interoccurrence ratio for 0.10-inch and greater precipitation threshold 

Adjusted median interoccurrence ratio for 0.05-inch and greater precipitation threshold 

Adjusted median interoccurrence ratio for 0.10-inch and greater precipitation threshold 

MONTH

J F MA MJ J A S O N D

1.50

0.50

0.55

0.60

0.65

0.70

0.75

0.80

0.85

0.90

0.95

1.00

1.05

1.10

1.15

1.20

1.25

1.30

1.35

1.40

1.45

ADJUSTED INTEROCCURRENCE RATIO, DIMENSIONLESS

Asquith and Thompson (2003) and Asquith 

(2003) concluded that for a 12- to 24-hour duration, an 

expected dimensionless hyetograph—cumulative temporal representation of storm depth—can be defined by 

the following equation: 

, (11)

where 

is the fractional percent of the 24-hour storm 

depth, and 

is the fractional percent of the storm duration. 

The equation is appropriate for a duration of 3 

hours because the interoccurrence intervals are derived 

for daily (24-hour) durations. Therefore, it follows that 

the equation estimates the median 3-hour, 6-month precipitation. For a duration of 3 hours, is 0.125 (3/24), 

and is 0.288. Hence the site-specific median 

3-hour, 6-month precipitation threshold for the Austin 

Camp Mabry station is 0.74 inch (0.288 × 2.56). For 

comparison, the site-specific median 6-hour, 6-month 

precipitation threshold is 1.20 inches (0.469 × 2.56).

p( ) F F0.7830e

0.4368 1( ) – F =

p( ) F

F

F

p( ) F

Figure 25. Relation between adjusted mean and median interoccurrence ratios and month for 0.05- and 0.10-inch 

daily precipitation thresholds for Texas.
EXAMPLE APPLICATIONS 29

Site-Specific Median Number of Occurrences

Suppose that the median number ( ) of occurrences in 1 year of daily precipitation with a threshold 

of 1.0 inch is needed for the Austin Camp Mabry 

station, which was considered in the previous section. 

The site-specific mean interoccurrence interval = 

37.41 days (sequence no. 46, table 5). The total time 

is 365 days, and because the median is sought, = 0.5. 

n Λ

T

F

Less frequent precipitation for a given threshold

More frequent precipitation for a given threshold

EXPLANATION

Adjusted mean interoccurrence ratio for 0.25-inch and greater precipitation threshold

Adjusted mean interoccurrence ratio for 0.50-inch and greater precipitation threshold

Adjusted mean interoccurrence ratio for 0.75-inch and greater precipitation threshold

Adjusted mean interoccurrence ratio for 1.0-inch and greater precipitation threshold

Adjusted mean interoccurrence ratio for 1.5-inch and greater precipitation threshold

Adjusted mean interoccurrence ratio for 2.0-inch and greater precipitation threshold

Adjusted mean interoccurrence ratio for 2.5-inch and greater precipitation threshold

Adjusted mean interoccurrence ratio for 3.0-inch and greater precipitation threshold

MONTH

J F MA MJ J A S O N D

1.50

0.50

0.55

0.60

0.65

0.70

0.75

0.80

0.85

0.90

0.95

1.00

1.05

1.10

1.15

1.20

1.25

1.30

1.35

1.40

1.45

ADJUSTED INTEROCCURRENCE RATIO, DIMENSIONLESS

Figure 26. Relation between adjusted mean interoccurrence ratio and month for 0.25-, 0.50-, 0.75-, 1.0-, 1.5-, 

2.0-, 2.5-, and 3.0-inch daily precipitation thresholds for Texas.
30 Atlas of Interoccurrence Intervals for Selected Thresholds of Daily Precipitation in Texas 

The estimated number of occurrences per year can be 

computed from equation 6: 

, and (12)

. (13)

The value for can be estimated using a spreadsheet or hand calculator. The right-hand side of equation 

0.5 e

–365 37.41 ⁄ ( ) ( ) 365 37.41 ⁄ n

n! ---------------------------------

i = 0

n

= ∑

8,635 ( ) 9.757 n

n! --------------------

i = 0

n

= ∑

n

Less frequent precipitation for a given threshold

More frequent precipitation for a given threshold

EXPLANATION

Adjusted median interoccurrence ratio for 0.25-inch and greater precipitation threshold 

Adjusted median interoccurrence ratio for 0.50-inch and greater precipitation threshold 

Adjusted median interoccurrence ratio for 0.75-inch and greater precipitation threshold 

Adjusted median interoccurrence ratio for 1.0-inch and greater precipitation threshold 

Adjusted median interoccurrence ratio for 1.5-inch and greater precipitation threshold 

Adjusted median interoccurrence ratio for 2.0-inch and greater precipitation threshold 

Adjusted median interoccurrence ratio for 2.5-inch and greater precipitation threshold 

Adjusted median interoccurrence ratio for 3.0-inch and greater precipitation threshold 

MONTH

J F MA MJ J A S O N D

1.50

0.50

0.55

0.60

0.65

0.70

0.75

0.80

0.85

0.90

0.95

1.00

1.05

1.10

1.15

1.20

1.25

1.30

1.35

1.40

1.45

ADJUSTED INTEROCCURRENCE RATIO, DIMENSIONLESS

Figure 27. Relation between adjusted median interoccurrence ratio and month for 0.25-, 0.50-, 0.75-, 1.0-, 1.5-, 

2.0-, 2.5-, and 3.0-inch daily precipitation thresholds for Texas.
EXAMPLE APPLICATIONS 31

13 for = 9 and = 10 is 8,442 and 10,597, respectively. The value 8,635 is closest to 8,442; therefore, the 

median number of precipitation events per year of 1.0 

inch and greater is estimated as 9.

Intra-Annual Variations in Interoccurrence 

Intervals

Suppose that the 75th ( = 0.75) and 90th ( = 

0.90) percentile of the number of occurrences of June 

precipitation in a 10-year period of successive months 

with a threshold of 0.25 inch in Lubbock, Tex. (fig. 4) is 

needed. The station at the Lubbock International Airport (sequence no. 717, table 1) has the longest period 

of record in the area (91 years), so the mean interoccurrence interval of 16.92 days is expected to be a 

reliable site-specific interval. The time is 10 years 

multiplied by 30 days in June or 300 days. The expected 

June interoccurrence interval is 10.83 (0.64 X 16.92) 

days using the June adjusted mean monthly interoccurrence ratio of 0.64 (table 12). The estimated number of 

occurrences for the 75th percentile can be computed 

from equation 6 as shown in the following equation: 

 . (14)

The value for that best approximates the number of June occurrences is 31 for the 75th percentile, and 

the value for that best approximates the equality is 34 

for the 90th percentile.

Regional Estimation of Mean Interoccurrence 

Interval

Suppose that estimates of the mean interoccurrence interval of precipitation are needed for the area 

surrounding Austin, Tex. The maps depicted in figures 

4–13 provide regional estimates that are believed to 

be generally more reliable than site-specific mean 

interoccurrence intervals available at any single station. 

Derived from the maps and manual interpolation, the 

regional estimates of interoccurrence intervals for each 

depth threshold for Austin are listed in table 20 (at 

end of report). For comparison, also listed in the table 

are the site-specific interoccurrence intervals for a 

long-term and short-term station in the Austin area 

(tables 3–7). The intervals in table 20 indicate that the 

regional estimates are similar to those for both stations; 

so the applicability of the maps in the Austin area is 

demonstrated.

n n

F F

T

0.75 e

–300 10.83 ⁄ ( ) 300 10.83 ⁄ n

n! ---------------------------------

i = 0

n

= ∑

n

n

0 0.5 1.0 1.5 2.0 2.5 3.0 3.5

DAILY PRECIPITATION THRESHOLD, IN INCHES

MEAN INTEROCCURRENCE INTERVAL, IN DAYS

[Log scale]

6

8

10

20

30

40

50

60

80

100

200

300

400

500

600

10

Station 428 Austin Camp Mabry

Depth_inches Interoccurrence_days

0.25 11.06

0.50 17.66

0.75 26.01

1.00 37.41

1.50 76.04

2.00 146.89

2.50 251.00

3.00 403.95

Sequence no. 46

Estimated threshold depth is 2.56 inches

Interoccurrence interval (263 days)

for median 6-month precipitation

Figure 28. Relation between site-specific daily precipitation threshold and mean interoccurrence interval for 

station 428 Austin Camp Mabry and estimated median 6-month precipitation.
32 Atlas of Interoccurrence Intervals for Selected Thresholds of Daily Precipitation in Texas 

SUMMARY

A Poisson process model of daily precipitation is 

used to model the distribution of precipitation interoccurrence intervals, and the mathematics of the model are 

described in this report. A precipitation interoccurrence 

interval is the time period between two successive rainfall events. Rainfall events are defined as daily precipitation that equals or exceeds specified depth threshold. 

Ten precipitation thresholds are considered and include 

depths of 0.05, 0.10, 0.25, 0.50, 0.75, 1.0, 1.5, 2.0, 2.5, 

and 3.0 inches. For each threshold for each of 1,306 

NWS daily precipitation stations, site-specific mean 

interoccurrence intervals and ancillary statistics are 

computed, and the results are tabulated. Maps depicting 

the spatial variation across Texas of the mean interoccurrence interval for each threshold are presented along 

with diagnostic statistics. The percent change from the 

statewide standard deviation of the interoccurrence 

intervals to the RMSE ranges from a magnitude minimum of (negative) -24 to a magnitude maximum of 

-60 percent for the 0.05- and 2.0-inch thresholds, 

respectively. Because of the substantial negative percent 

change, the maps are considered more reliable estimators of the mean interoccurrence interval for most locations in Texas than the statewide mean values.

The reliability of the maps west of the Pecos 

River is limited because of reduced station density, 

influences of elevation, and large interoccurrence intervals relative to the record length at the stations. Analysis 

of the influences of elevation on the interoccurrence 

intervals is provided. Interoccurrence interval decreases 

as station elevation increases, up to rainfall thresholds 

of about 1 inch, and for larger thresholds, little to no 

relation between interoccurrence interval and elevation is observed. Intra-annual variations or seasonal 

differences in the interoccurrence interval also are 

documented. Considerable and systematic seasonal 

variations reflect the decrease and increase in interoccurrence interval during the course of a year. 

Several applications of precipitation interoccurrence intervals are provided through example computations and interpretations. The Poisson model provides a 

framework to estimate the distribution of the number of 

event occurrences for specific time periods or the distribution of interoccurrence intervals. These distributions 

can be useful in surface-water hydrology.

SELECTED REFERENCES

Asquith, W.H., 1998, Depth-duration frequency of precipitation for Texas: U.S. Geological Survey Water-Resources 

Investigations Report 98–4044, 107 p.

______1999, Areal-reduction factors for the precipitation of 

the 1-day design storm in Texas: U.S. Geological Survey 

Water-Resources Investigations Report 99–4267, 81 p.

______2003, Modeling of runoff-producing rainfall hyetographs in Texas using L-moment statistics: Austin, 

University of Texas at Austin, Ph.D. dissertation, 386 p.

Asquith, W.H., and Famiglietti, J.S., 2000, Precipitation 

areal-reduction factor estimation using an annualmaxima centered approach: Journal of Hydrology, 

v. 230, p. 55–69.

Asquith, W.H., and Thompson, D.B., 2003, Modeling of 

runoff-producing rainfall hyetographs in Texas using 

L-moments, in Texas Section, Spring 2003 Meeting, 

Corpus Christi, Tex., April 2–5, 2003, Proceedings: 

American Society of Civil Engineers.

Bhat, U.N., and Miller, G.K., 2002, Elements of applied 

stochastic processes (3d ed.): Wiley, 461 p.

Bomar, G.W., 1995, Texas weather: Austin, University of 

Texas Press, 275 p.

Clarke, R.T., 1998, Stochastic processes for water scientists—Developments and applications: Wiley, 183 p.

Evans, Merran, Hastings, N.A.J., and Peacock, J.B., 2000, 

Statistical distributions (3d ed.): Wiley, 221 p.

Helsel, D.R., and Hirsch, R.M., 1992, Statistical methods in 

water resources—Studies in environmental science 49: 

Amsterdam, Elsevier, 529 p.

Hydrosphere, 2002, NCDC Summary of the day—West 2: 

Boulder, Colo., Hydrosphere Data Products, Inc., 

CD-ROM.

Isaaks, E.H., and Srivastava, R.M., 1989, An introduction to 

applied geostatistics: New York, Oxford University 

Press, 561 p.

Rajagopalan, Balaji, Lall, Upmanu, and Tarboton, D.G., 

1996, Nonhomogeneous Markov model for daily precipitation: American Society of Civil Engineers, Journal of 

Hydrologic Engineering, v. 1, no. 1, p. 33–40.

Ross, Sheldon, 1994, A first course in probability (4th ed.): 

New York, MacMillan College Publishing Co., 473 p.

Wilks, D.S., 1995, Statistical methods in the atmospheric 

sciences: San Diego, Academic Press, 467 p.
Table 1 33

Table 1

Atlas of Interoccurrence Intervals for Selected 

Thresholds of Daily Precipitation in Texas

Table 1. Summary of National Weather Service daily precipitation stations in Texas with known names, latitudes, 

and longitudes—Continued

Seq.

no. NWS station name

NWS

station

no.

County

Elev.

(ft above

NGVD 

29)

LatitudeLongitude

Begining

date

(mm/yyyy)

Ending

date

(mm/yyyy)

Percent

coverage

Years

of

record

1 Abernathy 12 Hale 3,360 33°50' 101°51' 01/1948 12/2001 99 54

2 Abilene 2 13 Taylor 1,865 32°12' 99°27' 05/2001 12/2001 66 1

3 Abilene Regional Airport 16 Taylor 1,790 32°24' 99°40' 01/1948 12/2001 100 54

4 Acker Ranch 25 McMullen 435 28°07' 98°32' 09/1978 12/2001 96 24

5 Ackerly 4 SE 34 Howard 2,655 32°30' 101°40' 01/1948 11/2001 96 54

6 Acton Ranch 40 Crockett 2,010 30°21' 101°15' 03/1992 12/2001 96 10

7 Adamsville 50 Lampasas 1,030 31°17' 98°09' 09/1963 12/1987 90 25

8 Adobe Walls Scout Camp 70 Wheeler 2,582 35°31' 100°22' 04/1974 03/1978 80 5

9 Adrian 68 Oldham* 4,042 35°17' 102°40' 05/1938 08/1948 72 11

10 Agua Dulce 73 Nueces 85 27°47' 97°54' 03/1987 09/1987 59 1

11 Agua Nueva 81 Jim Hogg 459 26°54' 98°36' 01/1948 12/1964 99 17

12 Albany 120 Shackelford 1,400 32°43' 99°18' 11/1901 12/2001 96 101

13 Aledo 4 SE 129 Parker 790 32°39' 97°34' 09/1960 12/2001 98 42

14 Alice 144 Jim Wells 201 27°43' 98°04' 04/1911 12/2001 96 85

15 Alice CAA Airport 145 Jim Wells 173 27°44' 98°02' 01/1948 09/1952 94 5

16 Allison 157 Wheeler 2,600 35°36' 100°03' 08/2001 12/2001 34 1

17 Allison Ranch 160 Edwards 2,280 30°05' 100°23' 10/1964 04/1965 17 2

18 Alpine 174 Brewster 4,530 30°21' 103°39' 03/1900 12/2001 94 80

19 Alto 5 SW 190 Cherokee 280 31°36' 95°08' 01/1948 12/2001 98 54

20 Alvarado 201 Johnson 689 32°25' 97°13' 01/1948 10/1964 99 17

21 Alvarado 2 NNW 202 Johnson 835 32°27' 97°13' 04/1987 12/2001 96 15

22 Alvin 204 Brazoria 28 29°22' 95°14' 06/1898 12/2001 93 102

23 Alvord 3 NE 206 Wise 1,010 33°23' 97°39' 06/1948 09/1951 81 4

24 Amarillo WSO Airport 211 Potter 3,586 35°13' 101°42' 01/1948 12/2001 100 54

25 Amistad Dam 225 Val Verde 1,157 29°27' 101°01' 05/1964 12/2001 99 38

26 Anahuac 235 Chambers 24 29°47' 94°40' 06/1909 12/2001 96 89

27 Anderson 244 Grimes 351 30°29' 95°59' 05/1914 09/1972 96 59

28 Andice 2 SW 246 Williamson 1,060 30°45' 97°51' 02/1968 12/2001 97 34

29 Andrews 248 Andrews 3,192 32°20' 102°33' 01/1914 12/2001 95 46

30 Angleton 2 W 257 Brazoria 27 29°09' 95°27' 06/1913 12/2001 97 89

31 Anna 262 Collin 680 33°21' 96°31' 06/1898 11/1995 95 52

32 Anson 268 Jones 1,710 32°46' 99°53' 01/1898 12/2001 86 53

33 Antelope 271 Jack 1,040 33°26' 98°22' 09/1910 12/2001 98 65

34 Aquilla 1 SSE 297 Hill 520 31°50' 97°13' 01/1992 12/2001 99 10

35 Aransas Pass 2 302 Aransas 20 27°55' 97°08' 06/1897 07/1971 91 31

36 Aransas Wildlife Refuge 305 Aransas 15 28°18' 96°48' 01/1971 12/2001 98 31

37 Aransas Wildlife Refuge 437 Aransas 20 28°16' 96°48' 06/1940 12/1970 96 31

38 Archer City 313 Archer 1,045 33°34' 98°37' 04/1910 12/2001 96 64

39 Arlington 337 Tarrant 655 32°44' 97°07' 01/1948 12/2001 99 54

40 Armstrong 342 Kenedy 30 26°56' 97°48' 08/1942 11/1978 84 34

41 Arthur City 367 Lamar* 430 33°52' 95°30' 01/1897 06/1970 94 72

42 Asherton 380 Dimmit* 551 28°26' 99°45' 06/1948 09/1951 51 4

43 Aspermont 394 Stonewall 1,670 33°09' 100°14' 07/1911 12/2001 97 91

44 Athens 404 Henderson 448 32°09' 95°49' 12/1903 12/2001 93 58

Table 1. Summary of National Weather Service daily precipitation stations in Texas with known names, latitudes, 

and longitudes 

[*, county name or elevation provided by authors—entry not available from Hydrosphere (2002). Abbreviations: Seq., sequence; NWS, 

National Weather Service; Elev., elevation; ft, feet; NGVD 29, National Geodetic Vertical Datum of 1929; mm/yyyy, month and year; CAA, 

Civilian Aviation Authority; WSO, Weather Service Office; SNA, State Natural Area; LCRA, Lower Colorado River Authority; FAA, 

Federal Aviation Authority; SCS, Soil Conservation Service; WB; Weather Bureau; WSFO, Weather Service Field Office; NWSO, National 

Weather Service Office; FCWOS, unknown; ASOS, unknown; CP&D, unknown; WTU, West Texas Utilities. Directions: SE, southeast; 

SW, southwest; NNW, north-northwest; NE, northeast; W, west; SSE, south-southeast; NW, northwest; N, north; NNE, north-northeast; 

ENE, east-northeast; SSW, south-southwest; WNW, west-northwest; S, south; WSW, west-southwest; E, east; ESE, east-southeast] 
34 Atlas of Interoccurrence Intervals for Selected Thresholds of Daily Precipitation in Texas 

45 Atlanta 408 Cass 300 33°06' 94°10' 09/1930 05/2000 91 57

46 Austin Camp Mabry 428 Travis 673 30°19' 97°46' 06/1930 12/2001 98 72

47 Austin Dam 430 Travis 531 30°18' 97°47' 03/1948 12/1965 97 18

48 Austin Montopolis Bridge 432 Travis* 512 30°15' 97°41' 01/1948 07/1963 97 16

49 Austin Water Treatment Plant 427 Travis 500 30°16' 97°39' 09/1996 07/1997 41 2

50 Austin-Bergstrom International Airport 429 Travis 480 30°10' 97°40' 07/1999 12/2001 83 3

51 Austwell 436 Refugio 95 28°22' 96°50' 03/1897 02/1960 96 52

52 Avalon 440 Ellis 530 32°12' 96°47' 12/1964 12/2001 94 38

53 Avery 5 NNW 443 Red River 390 33°37' 94°48' 03/2001 12/2001 84 1

54 Bade Ranch 463 Sterling* *2,433 31°50' 101°10' 06/1948 10/1948 24 1

55 Baird 478 Callahan 1,732 32°24' 99°24' 03/1948 04/1980 82 33

56 Bakers Crossing 479 Val Verde 1,510 29°57' 101°09' 01/1981 12/1987 93 7

57 Bakersfield 482 Pecos 2,553 30°53' 102°18' 01/1948 12/2001 99 54

58 Bakersfield 11 SSE 484 Pecos 3,081 30°43' 102°13' 07/1980 05/1982 55 3

59 Ballinger 2 NW 493 Runnels 1,755 31°44' 99°58' 01/1897 12/2001 96 103

60 Balmorhea 495 Reeves* 3,192 30°59' 103°44' 03/1949 06/1951 38 3

61 Balmorhea 498 Reeves 3,220 30°59' 103°44' 09/1923 12/2001 97 79

62 Balmorhea Circle H Ranch 497 Jeff Davis* 5,003 30°51' 103°59' 03/1953 10/1953 60 1

63 Balmorhea Graef Ranch 499 Reeves* 3,304 30°56' 103°31' 03/1953 11/1958 93 6

64 Balmorhea wb pan 496 Reeves* 3,222 31°00' 103°41' 01/1948 04/1950 27 3

65 Bankersmith 509 Kendall 1,750 30°08' 98°49' 06/1948 12/2001 92 22

66 Banquete 511 Nueces 79 27°48' 97°48' 07/1978 10/1986 71 9

67 Bardwell Dam 518 Ellis 461 32°15' 96°38' 04/1965 12/2001 99 37

68 Barnhart 528 Irion 2,562 31°08' 101°10' 03/1948 04/1965 80 18

69 Barstow 538 Ward* 2,572 31°28' 103°24' 05/1906 12/1919 96 14

70 Bastrop 542 Bastrop* 381 30°06' 97°20' 12/1900 02/1915 47 6

71 Bateman Ranch 556 King 1,811 33°35' 100°09' 05/1971 05/1973 69 3

72 Bateman Ranch 2 558 King 1,785 33°36' 100°13' 11/1974 10/1988 85 14

73 Batesville 560 Zavala 745 28°57' 99°37' 06/1965 03/2001 92 37

74 Bay City 2 N 572 Matagorda* 49 29°00' 95°58' 06/1948 09/1951 83 4

75 Bay City Waterworks 569 Matagorda 52 28°59' 95°57' 10/1909 12/2001 93 69

76 Baylor Ranch 580 La Salle* 400 28°18' 98°59' 07/1947 09/1951 63 5

77 Baytown 586 Harris 34 29°50' 95°00' 06/1946 12/2001 94 46

78 Bayview 576 Cameron* 20 26°07' 97°24' 06/1948 05/1950 66 3

79 Beasley 605 Fort Bend* 102 29°30' 95°52' 06/1948 09/1950 53 3

80 Beaumont City 611 Jefferson 20 30°06' 94°06' 11/1901 12/2001 96 101

81 Beaumont Research Center 613 Jefferson 27 30°04' 94°17' 01/1948 12/2001 94 41

82 Bedias 635 Grimes 335 30°47' 95°57' 08/1949 12/1985 94 37

83 Beeville 5 NE 639 Bee 255 28°27' 97°42' 11/1901 12/2001 98 100

84 Bellville 6 NNE 655 Austin 280 30°01' 96°12' 11/1978 12/2001 93 23

85 Belmont 660 Gonzales 388 29°31' 97°41' 02/1997 12/2001 90 5

86 Belton Dam 665 Bell 664 31°06' 97°29' 08/1951 12/1992 96 41

87 Benavides 689 Duval 381 27°36' 98°25' 06/1948 09/1951 83 4

88 Benavides 2 690 Duval 380 27°35' 98°24' 07/1962 12/2001 90 39

89 Benbrook Dam 691 Tarrant 790 32°38' 97°26' 06/1949 12/2001 98 53

90 Benjamin 15 W 708 King 1,650 33°35' 100°02' 05/1980 10/2001 79 22

91 Benjamin 4 SSE 704 Knox 1,401 33°32' 99°46' 06/1940 05/1975 94 36

92 Bertram 3 ENE 738 Burnet 1,139 30°45' 98°00' 02/1968 12/2001 100 34

93 Bethany 715 Panola 370 32°23' 94°03' 02/1983 12/1988 97 6

94 Big Bend Ranch SNA 764 Presidio 4,140 29°26' 103°57' 02/1995 12/2001 95 7

95 Big Lake 13 SSW 777 Crockett* 2,802 31°01' 101°33' 09/1941 04/1949 31 9

96 Big Lake 2 779 Reagan 2,703 31°11' 101°28' 08/1963 12/2001 97 39

Table 1. Summary of National Weather Service daily precipitation stations in Texas with known names, latitudes, 

and longitudes—Continued

Seq.

no. NWS station name

NWS

station

no.

County

Elev.

(ft above

NGVD 

29)

LatitudeLongitude

Begining

date

(mm/yyyy)

Ending

date

(mm/yyyy)

Percent

coverage

Years

of

record
Table 1 35

97 Big Lake LCRA 140 776 Reagan 2,690 31°12' 101°28' 06/1948 09/1951 77 4

98 Big Spring 786 Howard 2,500 32°14' 101°27' 01/1948 12/2001 97 54

99 Big Spring 5 NE 781 Howard 2,500 32°22' 101°25' 08/2001 11/2001 31 1

100 Big Wells 2 W 787 Dimmit 535 28°34' 99°35' 01/1916 12/2001 97 81

101 Bishop 805 Nueces 67 27°35' 97°48' 10/1934 12/2001 87 29

102 Blackwell 826 Nolan* 2,152 32°06' 100°18' 08/1936 08/1942 36 6

103 Blanco 832 Blanco 1,370 30°06' 98°25' 01/1897 12/2001 99 104

104 Blanket 839 Brown 1,601 31°49' 98°47' 03/1948 12/1965 95 18

105 Blewett 5 NW 852 Uvalde 971 29°14' 100°06' 05/1957 11/1985 97 29

106 Bloys Campground 861 Jeff Davis 5,764 30°32' 104°08' 05/1968 03/1978 89 11

107 Blue 866 Lee 459 30°24' 97°09' 03/1963 12/1984 93 22

108 Boerne 902 Kendall 1,444 29°47' 98°44' 07/1897 12/2001 98 104

109 Bon Wier 917 Newton 89 30°44' 93°39' 01/1948 06/1988 96 41

110 Bonham 3 NNE 923 Fannin 600 33°38' 96°10' 01/1903 12/2001 98 97

111 Bonita 4 NW 926 Montague 985 33°50' 97°39' 06/1948 12/2001 69 5

112 Booker 944 Lipscomb 2,750 36°27' 100°32' 05/1922 12/2001 90 70

113 Booker Blau Ranch 942 Lipscomb* 2,802 36°22' 100°32' 01/1948 11/1955 82 8

114 Bootleg Corner 947 Deaf Smith 4,114 34°50' 102°49' 12/1976 10/1982 78 7

115 Boquillas Ranger Station 950 Brewster 1,857 29°11' 102°57' 07/1910 12/2001 93 53

116 Borger 955 Hutchinson* 3,114 35°39' 101°24' 04/1944 10/1961 93 17

117 Borger 958 Hutchinson 3,067 35°41' 101°23' 02/1949 12/2001 99 53

118 Bovina 977 Parmer 4,104 34°31' 102°53' 08/1917 06/1920 69 4

119 Bowie 984 Montague 1,080 33°33' 97°50' 01/1897 11/2001 98 77

120 Boxelder 3 NNE 991 Red River 440 33°30' 94°51' 04/1949 12/2001 99 53

121 Boyd 996 Wise 730 33°04' 97°33' 01/1948 06/1999 97 52

122 Boys Ranch 1000 Oldham 3,191 35°31' 102°15' 07/1964 12/2001 91 26

123 Brackettville 1007 Kinney 1,118 29°19' 100°24' 02/1900 12/2001 95 99

124 Brackettville 22 N 1013 Kinney 1,675 29°36' 100°28' 09/1978 12/2001 86 24

125 Brady 1017 McCulloch 1,720 31°07' 99°20' 01/1897 12/2001 94 69

126 Brandon 1026 Hill 640 32°03' 96°58' 01/1992 12/2001 99 10

127 Bravo 1033 Hartley 4,160 35°37' 103°00' 01/1948 12/2001 98 54

128 Brazoria 1034 Brazoria* 30 29°03' 95°34' 01/1897 09/1929 93 32

129 Brazos 1035 Palo Pinto 840 32°38' 98°08' 09/1915 12/2001 98 55

130 Breckenridge 1042 Stephens 1,170 32°45' 98°54' 06/1898 12/2001 92 78

131 Breckenridge 2 WNW 1043 Stephens 1,332 32°46' 98°56' 03/1973 03/1975 69 3

132 Bremond 1045 Robertson 470 31°10' 96°41' 05/1963 12/2001 99 39

133 Brenham 1048 Washington 313 30°10' 96°24' 01/1902 12/2001 99 100

134 Brewers Store 5 SW 1053 Kimble* 1,762 30°41' 99°33' 06/1948 09/1951 82 4

135 Brice 2 S 1057 Hall 2,228 34°41' 100°54' 06/1948 09/1951 83 4

136 Bridgeport 1063 Wise 745 33°12' 97°46' 09/1915 12/2001 99 86

137 Briggs 1068 Burnet 1,090 30°53' 97°56' 06/1948 07/1998 88 11

138 Brighton 1073 Nueces* 10 27°39' 97°18' 01/1897 01/1920 91 23

139 Brite Ranch 1080 Presidio* 4,623 30°20' 104°32' 02/1949 08/1949 39 1

140 Britton 1081 Tarrant 561 32°33' 97°04' 06/1948 07/1952 71 5

141 Broaddus 4523 San Augustine 269 31°19' 94°17' 09/1947 12/1976 97 30

142 Broaddus 1 NE 1089 San Augustine 270 31°20' 94°13' 01/1977 12/2001 96 23

143 Bronson 1094 Sabine 322 31°21' 94°01' 07/1924 12/1979 95 52

144 Brownfield 1127 Terry* 3,383 33°11' 102°16' 03/1914 10/1954 94 40

145 Brownfield 2 1128 Terry 3,300 33°10' 102°15' 10/1953 12/2001 98 49

146 Brownsville WSO Airport 1136 Cameron 19 25°54' 97°25' 12/1898 12/2001 96 81

147 Brownwood 1138 Brown 1,385 31°40' 98°57' 01/1947 12/2001 97 55

148 Brunson Ranch 1150 Glasscock* 2,513 31°59' 101°42' 01/1948 06/1951 87 4

Table 1. Summary of National Weather Service daily precipitation stations in Texas with known names, latitudes, 

and longitudes—Continued

Seq.

no. NWS station name

NWS

station

no.

County

Elev.

(ft above

NGVD 

29)

LatitudeLongitude

Begining

date

(mm/yyyy)

Ending

date

(mm/yyyy)

Percent

coverage

Years

of

record
36 Atlas of Interoccurrence Intervals for Selected Thresholds of Daily Precipitation in Texas 

149 Bryan 17 NE 1156 Madison 92 30°52' 96°11' 05/1996 11/1996 58 1

150 Bryan CAA Airport 1154 Brazos* 266 30°38' 96°28' 06/1948 07/1951 79 4

151 Buchanan Dam 1165 Llano* 1,020 30°45' 98°25' 07/1943 02/1964 87 22

152 Buenavista 2 NNW 1185 Pecos* 2,513 31°15' 102°40' 06/1912 09/1951 94 23

153 Buffalo 1188 Leon 358 31°28' 96°03' 01/1948 11/1988 97 41

154 Buler 2 NE 1203 Ochiltree 2,972 36°11' 100°50' 01/1948 05/1977 97 30

155 Bulverde 1215 Comal 1,100 29°44' 98°27' 02/1940 12/2001 97 62

156 Bunker Hill 1224 Dallam 4,348 36°09' 102°56' 01/1948 07/1990 94 43

157 Bunton Ranch 1227 Presidio* 4,403 29°54' 104°17' 02/1948 04/1949 17 2

158 Burkburnett 2 NE 1236 Wichita 953 34°07' 98°32' 06/1996 12/2001 93 6

159 Burkett 1239 Coleman 1,555 31°59' 99°13' 03/1948 12/2001 89 54

160 Burleson 1246 Johnson 730 32°33' 97°19' 04/1985 12/2001 96 17

161 Burleson 2 SSW 1245 Johnson 771 32°31' 97°20' 01/1948 01/1985 97 38

162 Burlington 3 WSW 1248 Milam 410 31°00' 97°02' 01/1948 04/1975 96 28

163 Burnet 1250 Burnet 1,275 30°44' 98°14' 12/1896 12/2001 91 103

164 Burnet 9 WSW 1253 Burnet 880 30°44' 98°25' 08/2000 12/2001 71 2

165 Bushland 1 WSW 1267 Potter 3,819 35°11' 102°04' 06/1948 09/1951 81 4

166 Byrds 1 NNE 1285 Brown 1,450 31°56' 99°02' 03/1948 12/1965 96 18

167 Cadiz 1304 Bee* 351 28°26' 97°57' 06/1948 09/1951 83 4

168 Caldwell 1314 Burleson 365 30°32' 96°42' 03/1963 12/2001 99 39

169 Calhoun 1325 Colorado* 161 29°32' 96°20' 06/1948 09/1951 83 4

170 Callan 1334 Menard 2,123 31°03' 99°43' 03/1948 11/1965 93 18

171 Calliham 1337 McMullen 218 28°29' 98°23' 11/1978 12/2001 94 24

172 Cameron 1348 Milam 364 30°50' 96°58' 02/1908 12/2001 96 94

173 Cameron Ranch 1349 Starr* 459 26°33' 98°35' 04/1941 09/1946 90 6

174 Camp San Saba 1385 McCulloch 1,690 31°00' 99°16' 03/1948 12/1965 94 18

175 Camp Verde 3 W 1395 Kerr 1,800 29°53' 99°08' 02/1997 12/2001 76 5

176 Camp Wood 1398 Real 1,470 29°40' 100°01' 03/1944 12/2001 96 57

177 Canadian 1412 Hemphill 2,300 35°54' 100°23' 11/1906 11/2001 93 95

178 Canadian No. 2 1413 Hemphill 2,440 35°54' 100°22' 08/1946 02/1949 23 4

179 Candelaria 1416 Presidio 2,875 30°08' 104°40' 02/1948 12/2001 99 54

180 Canton 1425 Van Zandt 490 32°33' 95°52' 01/1948 06/2001 91 50

181 Canyon 1430 Randall 3,590 34°58' 101°55' 04/1923 12/2001 98 79

182 Canyon Dam 1429 Comal 1,000 29°52' 98°11' 06/1961 12/2001 93 41

183 Canyon Dam No. 1 1431 Comal 980 29°51' 98°17' 08/1996 12/2001 88 6

184 Canyon Dam No. 7 1438 Comal 978 29°55' 98°13' 10/1990 04/1993 59 4

185 Capps 1437 Moore* 3,304 36°03' 101°38' 05/1948 12/1956 67 9

186 Capps Ranch 1439 Mason* 1,703 30°50' 99°07' 03/1948 05/1959 52 12

187 Carbon 1451 Eastland 1,590 32°16' 98°50' 11/2001 12/2001 17 1

188 Carr Ranch 1481 Gillespie 2,001 30°10' 99°07' 07/1920 11/1961 97 42

189 Carrizo Springs 1486 Dimmit 613 28°29' 99°52' 04/1912 12/2001 93 78

190 Carrollton 1490 Dallas 545 32°59' 96°55' 01/1948 03/2001 96 54

191 Carta Valley 4 W 1492 Val Verde 1,780 29°48' 100°44' 08/1963 12/2000 92 38

192 Carthage 1500 Panola 340 32°08' 94°21' 01/1908 12/2001 96 52

193 Case Ranch 3 S 1511 Sterling 2,192 31°38' 101°02' 03/1948 12/1983 93 36

194 Castell 1521 Llano 1,211 30°42' 98°58' 03/1948 02/1980 53 33

195 Castolon 1524 Brewster 2,169 29°08' 103°30' 02/1947 12/2001 93 28

196 Catarina 1528 Dimmit 560 28°20' 99°37' 04/1959 10/2001 92 43

197 Cedar Creek 4 SE 1541 Bastrop 470 30°02' 97°27' 04/1978 12/2001 96 23

198 Celina 1573 Collin 679 33°19' 96°48' 01/1948 02/1983 96 36

199 Center 1578 Shelby 325 31°48' 94°09' 07/1922 12/2001 95 66

200 Center City 1580 Mills 1,365 31°28' 98°25' 05/1963 12/2001 99 39

Table 1. Summary of National Weather Service daily precipitation stations in Texas with known names, latitudes, 

and longitudes—Continued

Seq.

no. NWS station name

NWS

station

no.

County

Elev.

(ft above

NGVD 

29)

LatitudeLongitude

Begining

date

(mm/yyyy)

Ending

date

(mm/yyyy)

Percent

coverage

Years

of

record
Table 1 37

201 Centerville 1596 Leon 320 31°15' 95°58' 05/1937 12/2001 97 65

202 Chalk 1622 Cottle 1,780 33°53' 100°13' 09/1990 12/1991 66 2

203 Chalk Mountain 1625 Erath 1,150 32°09' 97°56' 04/1963 12/2001 99 39

204 Chambers Hill Guard Station 1632 Sabine* 351 31°28' 93°50' 01/1948 03/1952 76 5

205 Chancellor 1641 Pecos* 3,402 30°42' 103°11' 06/1948 09/1951 26 4

206 Channing 1646 Hartley 3,800 35°41' 102°20' 08/1904 09/1951 73 11

207 Channing 11 NE 1650 Moore 3,725 35°46' 102°09' 03/1990 07/1991 71 2

208 Channing 2 1649 Hartley 3,790 35°41' 102°19' 05/1967 12/2001 90 25

209 Chapman Ranch 1651 Nueces 25 27°35' 97°27' 04/1959 12/2001 97 43

210 Chappel 1655 San Saba* 1,240 31°04' 98°34' 03/1948 12/1959 98 12

211 Charlie 1659 Clay 950 34°06' 98°19' 06/1996 12/2001 93 6

212 Charlotte 5 NNW 1663 Atascosa 441 28°55' 98°44' 07/1962 12/2001 98 40

213 Cheapside 1671 Gonzales 310 29°18' 97°20' 06/1948 12/2001 87 10

214 Cherokee 1680 San Saba 1,490 30°59' 98°43' 06/1948 09/1951 80 4

215 Childress 13 NW 1697 Childress 1,713 34°34' 100°20' 02/1975 06/1978 54 4

216 Childress 2 1694 Childress 1,940 34°25' 100°12' 11/1997 12/2001 83 5

217 Childress 3 WSW 1696 Childress 1,972 34°26' 100°15' 01/1897 12/1946 94 44

218 Childress Municipal Airport 1698 Childress 1,951 34°25' 100°17' 01/1948 12/2001 96 53

219 Childress Ranch 1699 Jeff Davis* *4,413 31°00' 104°02' 01/1948 01/1948 8 1

220 Chillicothe 2 NE 1701 Hardeman 1,401 34°15' 99°31' 09/1906 03/1975 96 70

221 Chireno 1711 Nacogdoches 330 31°30' 94°21' 02/1989 12/2001 99 13

222 Chisos Basin 1715 Brewster 5,300 29°16' 103°18' 02/1947 12/2001 98 55

223 Choke Canyon Dam 1720 Live Oak 230 28°28' 98°15' 10/1983 12/2001 94 19

224 Christoval 1735 Tom Green 2,031 31°12' 100°29' 03/1948 12/1965 93 18

225 Cibolo Creek 1741 Karnes 312 29°01' 97°56' 01/1948 10/1982 92 35

226 Clarendon 1761 Donley 2,700 34°55' 100°53' 05/1904 12/2001 95 96

227 Clarksville 1 W 1773 Red River 426 33°36' 95°01' 06/1948 09/1951 82 4

228 Clarksville 2 NE 1772 Red River 435 33°36' 95°04' 03/1903 12/2001 96 97

229 Classens Ranch 1777 Bexar 1,001 29°39' 98°22' 01/1947 05/1972 96 26

230 Claude 1778 Armstrong 3,395 35°06' 101°21' 10/1904 12/2001 89 98

231 Cleburne 1800 Johnson 783 32°20' 97°24' 01/1907 12/2001 96 94

232 Cleburne 7 SE 1804 Johnson 830 32°19' 97°18' 03/1995 12/2001 98 7

233 Cleveland 1810 Liberty 196 30°21' 95°05' 06/1954 12/2001 99 48

234 Clifton 2 1824 Bosque 765 31°47' 97°35' 01/1992 10/1994 94 3

235 Clifton 9 E 1823 Bosque 669 31°48' 97°26' 03/1911 07/1975 98 65

236 Cline 1832 Uvalde 1,001 29°15' 100°05' 06/1940 04/1957 87 18

237 Clodine 1838 Fort Bend 87 29°42' 95°41' 01/1943 12/2001 91 56

238 Cloudt Ranch 1843 Edwards 2,251 30°11' 100°22' 01/1949 08/1964 73 16

239 Coldspring 5 SSW 1870 San Jacinto 355 30°32' 95°09' 06/1954 12/2001 99 48

240 Coldwater 1874 Dallam 4,134 36°24' 102°34' 03/1941 10/1983 85 42

241 Coleman 1875 Coleman 1,727 31°49' 99°25' 12/1896 12/2001 98 105

242 College Station Easterwood 1889 Brazos 314 30°35' 96°21' 08/1951 12/2001 98 49

243 College Station 6 SW 1888 Brazos 175 30°32' 96°25' 10/1901 05/1984 94 60

244 College Station Agricultural Experiment Station 1891 Burleson 225 30°33' 96°26' 06/1981 08/1981 25 1

245 Colorado City 1903 Mitchell 2,105 32°23' 100°53' 07/1898 12/2001 93 78

246 Columbus 1911 Colorado 199 29°43' 96°32' 04/1915 12/2001 98 56

247 Comanche 1914 Comanche 1,345 31°54' 98°35' 04/1901 12/2001 95 88

248 Comfort 2 1920 Kendall 1,435 29°57' 98°53' 08/1996 12/2001 90 6

249 Commerce 4 SW 1921 Hunt 550 33°12' 95°56' 08/1948 12/2001 82 10

250 Comstock 1925 Val Verde 1,584 29°41' 101°11' 11/1903 09/1987 81 25

251 Comstock 11 WNW 1926 Val Verde 1,260 29°42' 101°21' 03/1992 01/1993 33 2

252 Concepcion 3 S 1932 Duval 260 27°21' 98°22' 05/1941 07/2001 79 8

Table 1. Summary of National Weather Service daily precipitation stations in Texas with known names, latitudes, 

and longitudes—Continued

Seq.

no. NWS station name

NWS

station

no.

County

Elev.

(ft above

NGVD 

29)

LatitudeLongitude

Begining

date

(mm/yyyy)

Ending

date

(mm/yyyy)

Percent

coverage

Years

of

record
38 Atlas of Interoccurrence Intervals for Selected Thresholds of Daily Precipitation in Texas 

253 Concho Park Ivie Reservoir 1934 Concho 1,575 31°33' 99°42' 03/1998 12/2001 96 4

254 Conlen 1946 Dallam 3,820 36°14' 102°14' 01/1948 12/2001 99 54

255 Conroe 1956 Montgomery 245 30°20' 95°29' 01/1948 12/2001 98 54

256 Cooper 1970 Delta 480 33°22' 95°41' 01/1948 02/2001 92 54

257 Coopers Store 1972 Brewster* 2,904 29°35' 103°08' 02/1948 04/1951 42 4

258 Cope Ranch 1974 Reagan 2,480 31°31' 101°16' 03/1948 12/2001 99 54

259 Copper Breaks State Park 1995 Hardeman 1,475 34°06' 99°44' 05/1989 12/2001 95 13

260 Copperas Cove 1984 Coryell 1,070 31°07' 97°54' 09/1915 07/1983 92 66

261 Copperas Cove 2 1986 Coryell 1,240 31°07' 97°55' 02/1966 01/1970 80 5

262 Copperas Cove 5 NW 1990 Coryell 1,230 31°10' 97°58' 08/1983 12/2001 97 19

263 Cornudas Service Station 2012 Hudspeth 4,480 31°47' 105°28' 05/1948 05/2001 94 54

264 Corpus Christi 2014 Nueces 10 27°48' 97°24' 12/1946 08/1980 93 35

265 Corpus Christi WSO Airport 2015 Nueces 41 27°46' 97°30' 01/1948 12/2001 100 54

266 Corrigan 1 ENE 2017 Polk 200 30°59' 94°49' 01/1992 12/2001 91 10

267 Corsicana 2019 Navarro 413 32°06' 96°28' 01/1897 12/2001 98 102

268 Corsicana 8 E 2020 Navarro 376 32°07' 96°20' 01/1992 12/2001 100 10

269 Coryell City 2024 Coryell 971 31°33' 97°37' 06/1948 09/1951 49 4

270 Cottonwood 2040 Gillespie 2,235 30°09' 99°08' 07/1962 12/2001 97 40

271 Cottonwood Dam No. 2 2043 El Paso *3,910 31°32' 106°04' 06/1948 11/1948 42 1

272 Cottonwood Dam 1 2042 El Paso* 3,852 31°33' 106°05' 09/1948 03/1949 21 2

273 Cotulla 2048 La Salle 452 28°27' 99°13' 06/1901 12/2001 94 93

274 Cotulla FAA Airport 2050 La Salle 463 28°27' 99°13' 10/1949 10/1981 94 33

275 Cotulla Hillje Ranch 2051 La Salle 331 28°14' 99°04' 04/1956 10/1964 82 8

276 Cox Ranch 2066 Concho 1,903 31°21' 99°53' 03/1948 12/1965 98 18

277 Crabb 2 W 2073 Fort Bend* 112 29°32' 95°45' 06/1948 09/1951 77 4

278 Crandall 2080 Kaufman 425 32°38' 96°27' 09/1960 01/1994 93 35

279 Crane 10 N 2084 Crane 2,630 31°40' 102°20' 11/1999 12/2001 67 3

280 Crane 2 E 2082 Crane 2,602 31°24' 102°18' 05/1928 12/2001 94 48

281 Cranfills Gap 2086 Bosque 975 31°46' 97°50' 07/1948 12/2001 86 14

282 Crawford 2088 McLennan 705 31°32' 97°26' 01/1992 12/2001 73 5

283 Cresson 2096 Hood 1,050 32°32' 97°37' 06/1948 12/2001 98 54

284 Crider Ranch 2104 Real 2,323 30°04' 99°44' 01/1948 05/1975 93 28

285 Crockett 2114 Houston 347 31°18' 95°27' 08/1904 09/2001 97 92

286 Crosbyton 2121 Crosby 3,010 33°35' 101°14' 01/1897 12/2001 98 104

287 Cross 2125 McMullen 285 28°35' 98°33' 01/1997 12/2001 100 5

288 Cross Plains 1 2128 Callahan 1,742 32°07' 99°10' 04/1939 09/1976 95 38

289 Cross Plains 2 2131 Callahan 1,790 32°07' 99°09' 06/1948 09/1951 78 4

290 Crowell 2142 Foard 1,455 33°59' 99°43' 08/1916 12/2001 97 86

291 Crystal City 2160 Zavala 580 28°40' 99°49' 07/1948 12/2001 99 54

292 Cuero 2170 DeWitt* 180 29°04' 97°17' 01/1948 12/1953 100 6

293 Cuero 2173 DeWitt 178 29°05' 97°19' 12/1901 12/2001 97 100

294 Cypress 2206 Harris 150 29°58' 95°42' 01/1948 12/2001 97 53

295 Cypress Mill 2210 Blanco 922 30°23' 98°15' 03/1948 09/1964 96 17

296 Dacus 2218 Montgomery 240 30°25' 95°47' 06/1954 12/2001 98 48

297 Daingerfield 9 S 2225 Morris 300 32°55' 94°43' 01/1948 12/2001 99 54

298 Dallas-Fort Worth International Airport 2242 Tarrant 560 32°53' 97°01' 01/1974 12/2001 100 28

299 Dalhart 2238 Dallam* 4,003 36°05' 102°29' 04/1948 12/1948 64 1

300 Dalhart 6 SW 2235 Hartley 4,000 36°00' 102°36' 08/1988 12/2001 95 14

301 Dalhart Experiment Station 2239 Hartley* 4,003 36°01' 102°35' 11/1905 12/1953 94 49

302 Dalhart FAA Airport 2240 Hartley 3,990 36°01' 102°32' 12/1948 12/2001 98 54

303 Dallas Arboretum 2228 Dallas 495 32°49' 96°43' 04/1989 07/1990 67 2

304 Dallas Love Field 2244 Dallas 440 32°51' 96°51' 01/1897 12/2001 97 71

Table 1. Summary of National Weather Service daily precipitation stations in Texas with known names, latitudes, 

and longitudes—Continued

Seq.

no. NWS station name

NWS

station

no.

County

Elev.

(ft above

NGVD 

29)

LatitudeLongitude

Begining

date

(mm/yyyy)

Ending

date

(mm/yyyy)

Percent

coverage

Years

of

record
Table 1 39

305 Dallas WFAA 2247 Dallas* 479 32°46' 96°47' 11/1941 04/1951 53 8

306 Danevang 1 W 2266 Wharton 70 29°03' 96°13' 01/1897 12/2001 98 104

307 Darrouzett 2282 Lipscomb 2,540 36°26' 100°19' 11/1941 12/2001 95 61

308 Davilla 2 N 2295 Milam 556 30°48' 97°16' 01/1948 12/2001 90 54

309 Dawson 2309 Navarro* 479 31°54' 96°43' 06/1948 09/1951 80 4

310 De Leon 6 W 2350 Comanche 1,330 32°06' 98°39' 01/1992 12/2001 85 10

311 De Long Ranch 2317 Schleicher* 2,402 30°59' 100°48' 04/1948 11/1958 95 11

312 Decatur 2334 Wise 1,025 33°13' 97°35' 10/1904 12/2001 91 56

313 Decatur 2 SSW 2338 Wise 922 33°12' 97°36' 01/1966 09/1972 96 7

314 Decatur 7 N 2336 Wise* 902 33°20' 97°35' 06/1948 09/1951 77 4

315 Dekalb 2352 Bowie 400 33°38' 94°38' 01/1948 12/2001 95 54

316 Del Rio 2 NW 2361 Val Verde 1,080 29°25' 100°54' 08/1996 12/2001 90 6

317 Del Rio 3 S 2362 Val Verde* 879 29°20' 100°53' 01/1948 02/1954 64 7

318 Del Rio Airport 2360 Val Verde 999 29°22' 100°55' 05/1951 12/2001 98 46

319 Del Rio Webb City 2357 Val Verde* 961 29°22' 100°54' 02/1946 02/1963 79 13

320 Dell City 5 SSW 2354 Hudspeth 3,770 31°52' 105°14' 07/1979 12/2001 95 23

321 Denison Dam 2394 Grayson 613 33°49' 96°34' 02/1940 06/1997 98 58

322 Denison Highway 60 Bridge 2397 Grayson* 551 33°49' 96°32' 05/1909 05/1949 93 37

323 Denton 2403 Denton 659 33°14' 97°08' 03/1949 01/1965 86 17

324 Denton 2 SE 2404 Denton 630 33°11' 97°06' 06/1913 12/2001 97 89

325 Denver City 2408 Yoakum 3,590 32°57' 102°49' 05/1986 12/2001 78 15

326 Deport 4 NW 2415 Lamar 436 33°33' 95°22' 06/1948 03/2001 81 22

327 Derby 1 S 2417 Frio 470 28°45' 99°08' 04/1978 12/2001 93 24

328 Devine 2430 Medina* 689 29°09' 98°54' 07/1948 05/1954 38 7

329 Deweyville 5 S 2436 Orange 20 30°14' 93°44' 05/1954 04/1986 96 33

330 Dialville 2 W 2444 Cherokee 616 31°54' 95°15' 09/1897 12/2001 96 104

331 Dickens 2448 Dickens 2,575 33°37' 100°50' 06/1964 10/1984 87 21

332 Dilley 2458 Frio 550 28°40' 99°10' 03/1910 12/2001 98 89

333 Dime Box 2462 Lee 335 30°21' 96°50' 10/1941 12/2001 96 61

334 Dimmitt 2 N 2464 Castro 3,850 34°35' 102°18' 05/1959 12/2001 98 43

335 Dimmitt 6 E 2463 Castro 3,812 34°33' 102°13' 01/1923 06/1985 97 63

336 Divide School 2478 Kerr* 2,552 30°07' 99°37' 12/1941 02/1948 71 8

337 Doole 6 NNE 2527 McCulloch 1,450 31°29' 99°34' 04/1948 07/1979 94 32

338 Doss 2541 Gillespie 1,801 30°27' 99°08' 03/1948 12/1965 88 18

339 Douglass 1 S 2558 Nacogdoches 385 31°38' 94°53' 08/1983 12/2001 89 15

340 Dripping Springs 6 E 2585 Hays 1,120 30°12' 97°58' 12/1984 12/2001 95 18

341 Dryden 2590 Terrell 2,190 30°03' 102°07' 06/1966 10/1994 92 29

342 Dryden 10 NE 2593 Terrell 2,280 30°12' 101°50' 05/1937 08/1993 86 13

343 Dryer 1 NW 2595 Gonzales 302 29°23' 97°16' 02/1940 04/1975 97 36

344 Dublin 2598 Erath 1,502 32°06' 98°20' 11/1898 12/2001 92 102

345 Dublin near SCS 7 2599 Erath* 1,470 32°06' 98°15' 08/1941 06/1943 44 3

346 Dumas 2617 Moore 3,655 35°52' 101°58' 01/1937 12/2001 91 65

347 Dumas 8 NE 2619 Moore 3,553 35°57' 101°53' 06/1948 09/1951 82 4

348 Dumont 2621 King 2,010 33°48' 100°31' 05/1971 12/2001 99 31

349 Duncan Wilson Ranch 2630 Schleicher 2,120 30°48' 100°10' 02/1966 11/1996 98 31

350 Dundee 6 NNW 2633 Archer 1,051 33°48' 98°55' 06/1922 12/2001 96 80

351 Dunk Ranch 2636 Kimble* 2,201 30°22' 99°36' 03/1948 09/1958 96 11

352 E V Ranch 3013 Jeff Davis* 4,423 30°53' 104°27' 02/1919 06/1923 73 4

353 EADS 2669 Smith* 522 32°34' 95°25' 01/1948 01/1958 81 11

354 Eagle Mountain Lake 2677 Tarrant 760 32°52' 97°26' 04/1978 12/2001 86 22

355 Eagle Mountain Lake Dam 2678 Tarrant 679 32°53' 97°28' 07/1940 04/1975 90 34

356 Eagle Pass 2679 Maverick 808 28°42' 100°28' 02/1900 12/2001 97 101

Table 1. Summary of National Weather Service daily precipitation stations in Texas with known names, latitudes, 

and longitudes—Continued

Seq.

no. NWS station name

NWS

station

no.

County

Elev.

(ft above

NGVD 

29)

LatitudeLongitude

Begining

date

(mm/yyyy)

Ending

date

(mm/yyyy)

Percent

coverage

Years

of

record
40 Atlas of Interoccurrence Intervals for Selected Thresholds of Daily Precipitation in Texas 

357 Eastland 2715 Eastland 1,433 32°23' 98°49' 04/1904 12/2001 94 92

358 Eden 1 2741 Concho 2,064 31°13' 99°50' 04/1923 02/1983 92 56

359 Eden 2 2744 Concho 2,070 31°13' 99°51' 06/1948 10/1986 76 8

360 Edinburg 2758 Hidalgo 96 26°17' 98°09' 06/1948 05/1950 66 3

361 Edmonson 2766 Hale* 3,481 34°17' 101°54' 02/1947 06/1947 41 1

362 Edna 3 SW 2769 Jackson 69 28°57' 96°41' 07/1909 02/1968 97 60

363 Edna 7 NW 2770 Jackson 70 29°03' 96°45' 12/1995 12/2001 86 7

364 Edna Highway 59 Bridge 2768 Jackson 68 28°58' 96°41' 03/1968 11/1995 94 28

365 Edom 2772 Van Zandt 508 32°22' 95°37' 04/1940 12/2001 98 62

366 Egypt 2780 Wharton* 131 29°24' 96°14' 05/1921 05/1928 86 8

367 El Campo 2786 Wharton 112 29°12' 96°17' 10/1941 04/1974 93 34

368 El Indio 2824 Maverick 700 28°30' 100°18' 09/1978 12/2001 96 24

369 El Paso No. 2 2793 El Paso 3,918 31°48' 106°22' 08/2001 12/2001 34 1

370 El Paso 32 ENE 2794 Hudspeth 5,240 31°50' 105°57' 11/1983 12/2001 94 19

371 El Paso Airport 2797 El Paso 3,918 31°48' 106°22' 01/1948 12/2001 100 54

372 Eldorado 11 NW 2812 Schleicher 2,490 30°58' 100°42' 12/1958 06/1981 93 24

373 Eldorado 11 SW 2813 Schleicher* 2,431 30°47' 100°46' 02/1949 09/1951 17 3

374 Eldorado 12 N 2815 Schleicher 2,380 31°02' 100°35' 08/1999 12/2001 80 3

375 Eldorado 19 SW 2814 Schleicher* 2,362 30°44' 100°53' 09/1941 09/1975 89 33

376 Eldorado 2 SE 2792 Schleicher 2,434 30°50' 100°35' 09/1981 08/1989 89 9

377 Electra 2818 Wichita 1,216 34°02' 98°55' 01/1948 10/2001 92 54

378 Elgin 2820 Bastrop 579 30°20' 97°22' 02/1962 12/2001 100 40

379 Elmax Ranch 2830 Kendall 1,524 29°53' 98°39' 01/1986 07/1986 50 1

380 Elmendorf 2850 Bexar 702 29°25' 98°20' 05/1916 04/1920 78 5

381 Emory 2902 Rains 435 32°51' 95°46' 05/1897 12/2001 87 60

382 Emory 8 S 2904 Van Zandt 370 32°46' 95°45' 08/1992 07/1993 40 2

383 Encinal 2906 Webb 590 28°02' 99°25' 11/1907 12/2001 93 95

384 Engleman Gardens 2917 Hidalgo 69 26°20' 98°01' 09/1946 02/1970 89 25

385 Ennis 2925 Ellis 525 32°20' 96°38' 05/1940 12/1991 96 49

386 Eola 2934 Concho* *1,791 31°24' 100°05' 08/1911 11/1912 33 2

387 Era 2941 Cooke* 951 33°30' 97°18' 09/1946 08/1953 71 8

388 Estelle 2965 Dallas* *549 32°52' 97°01' 01/1897 12/1904 96 7

389 Euless 2983 Tarrant* 551 32°49' 97°06' 02/1946 05/1953 33 3

390 Evadale 3000 Jasper 33 30°20' 94°05' 09/1946 12/2001 98 49

391 Evant 1 SSW 3005 Coryell 1,245 31°28' 98°10' 10/1941 12/2001 91 48

392 Exxon Gas Plant 3025 Kleberg 84 27°28' 97°47' 07/1998 10/2001 71 4

393 Fabens 1 3033 El Paso 3,612 31°30' 106°09' 06/1948 09/1977 97 30

394 Fabens 2 3034 El Paso* 3,652 31°31' 106°09' 07/1949 07/1949 8 1

395 Fair Oaks Ranch 3038 Comal 1,302 29°45' 98°38' 12/1946 01/1973 89 28

396 Fairfield 3 W 3047 Freestone 432 31°43' 96°12' 03/1941 12/2001 90 60

397 Falcon Dam 3060 Starr 320 26°33' 99°08' 07/1962 12/2001 97 40

398 Falfurrias 3063 Brooks 120 27°12' 98°07' 03/1907 12/2001 97 95

399 Falls City 7 WSW 3065 Karnes 343 28°57' 98°06' 08/1946 12/2001 96 56

400 Farmersville 3080 Collin 630 33°10' 96°22' 09/1947 12/2001 96 55

401 Farnsworth 3 NNW 3085 Ochiltree* 3,002 36°22' 100°59' 01/1941 01/1958 88 18

402 Fawcett Ranch 3103 Val Verde* 1,503 29°52' 100°54' 06/1948 02/1949 33 2

403 Fedor 3112 Lee 483 30°18' 97°03' 03/1963 12/2001 95 39

404 Ferris 3133 Ellis 470 32°31' 96°40' 01/1940 12/2001 94 60

405 Fife 3142 McCulloch 1,391 31°23' 99°22' 08/1941 07/1975 93 35

406 Fischers store 3156 Comal 1,160 29°58' 98°15' 04/1941 12/2001 97 61

407 Flat 3171 Coryell 835 31°19' 97°38' 08/1951 12/2001 92 11

408 Flatonia 3183 Fayette 520 29°40' 97°06' 01/1908 12/2001 99 94

Table 1. Summary of National Weather Service daily precipitation stations in Texas with known names, latitudes, 

and longitudes—Continued

Seq.

no. NWS station name

NWS

station

no.

County

Elev.

(ft above

NGVD 

29)

LatitudeLongitude

Begining

date

(mm/yyyy)

Ending

date

(mm/yyyy)

Percent

coverage

Years

of

record
Table 1 41

409 Fletcher Ranch 3189 Presidio* 4,852 30°10' 104°12' 06/1948 09/1951 83 4

410 Flint 3192 Smith* 479 32°12' 95°21' 02/1910 08/1949 99 40

411 Flomot 4 NE 3196 Motley 2,360 34°16' 100°56' 08/1946 12/2001 94 56

412 Florence 3 SE 3199 Williamson 970 30°48' 97°45' 03/1963 12/2001 97 39

413 Floresville 3201 Wilson 400 29°07' 98°09' 06/1916 12/2001 96 86

414 Flour Bluff 3210 Nueces 9 27°36' 97°17' 09/1988 07/1998 85 11

415 Floydada 3214 Floyd 3,220 33°59' 101°20' 04/1911 12/2001 93 63

416 Floydada 9 SE 3215 Floyd 3,130 33°52' 101°14' 01/1947 12/2001 96 55

417 Flying V Ranch 3218 San Saba* 1,631 31°05' 98°45' 06/1948 12/1959 70 12

418 Follett 3225 Lipscomb 2,769 36°26' 100°08' 06/1930 06/2001 95 72

419 Forestburg 5 S 3247 Montague 1,110 33°27' 97°34' 01/1897 12/2001 97 64

420 Forsan 3253 Howard 2,750 32°06' 101°21' 04/1949 12/2001 99 53

421 Fort Davis 3262 Jeff Davis 4,880 30°39' 103°53' 01/1902 12/2001 95 90

422 Fort Hancock 8 SSE 3266 Hudspeth 3,905 31°11' 105°44' 07/1966 12/2001 88 36

423 Fort McIntosh 3267 Webb* 459 27°30' 99°31' 01/1897 12/1931 96 33

424 Fort McKavett 14 NW 3271 Schleicher 2,280 30°57' 100°16' 12/1958 03/1962 15 4

425 Fort Stockton 3280 Pecos 3,000 30°54' 102°54' 05/1940 12/2001 95 61

426 Fort Stockton 1 3277 Pecos* 3,051 30°53' 102°53' 01/1897 12/1948 96 51

427 Fort Worth Clear Fork 3287 Tarrant 533 32°44' 97°22' 08/1947 08/1947 8 1

428 Fort Worth Leonard Boulevard 3286 Tarrant 659 32°44' 97°20' 07/1953 08/1966 94 14

429 Fort Worth Meacham Field 3284 Tarrant 687 32°49' 97°21' 09/1946 12/2001 87 17

430 Fort Worth WB Airport 3283 Tarrant 574 32°50' 97°03' 01/1897 12/1973 90 27

431 Fort Worth WSFO 3285 Tarrant 644 32°50' 97°18' 08/1948 12/2001 88 12

432 Four Notch Guard Station 3298 Walker 302 30°39' 95°25' 07/1940 12/1964 95 25

433 Fowlerton 3299 La Salle 320 28°28' 98°49' 06/1913 12/2001 88 85

434 Franklin 3321 Robertson 469 31°02' 96°29' 04/1962 12/2001 93 40

435 Frankston 3 WNW 3325 Anderson 430 32°04' 95°33' 12/1963 10/1966 71 4

436 Fredericksburg 3329 Gillespie 1,685 30°14' 98°54' 12/1896 12/2001 97 82

437 Freeport 2 NW 3340 Brazoria 8 28°59' 95°23' 01/1931 12/2001 98 71

438 Freer 3341 Duval 510 27°54' 98°37' 12/1947 12/2001 93 55

439 Freer 18 WNW 3344 Webb 336 27°56' 98°52' 07/1978 12/2001 93 24

440 Frio Town 3366 Frio 630 29°02' 99°19' 09/1947 11/1979 91 28

441 Friona 3368 Parmer 4,010 34°38' 102°42' 11/1927 12/2001 91 71

442 Frisco 3370 Collin 740 33°09' 96°49' 11/1966 12/2001 97 36

443 Frost 3379 Navarro 522 32°05' 96°48' 10/1946 02/1985 89 40

444 Fort McKavett 3257 Menard 2,310 30°49' 100°06' 08/1997 12/2001 88 5

445 Funk Ranch 3401 Irion 2,070 31°29' 100°48' 03/1948 12/2001 97 54

446 Gageby 3 WNW 3410 Hemphill 2,800 35°37' 100°23' 06/1948 09/1951 81 4

447 Gail 3411 Borden 2,530 32°46' 101°26' 01/1897 09/2001 88 71

448 Gainesville 3415 Cooke 780 33°38' 97°08' 01/1897 03/1987 97 89

449 Gainesville 5 ENE 3420 Cooke 870 33°38' 97°03' 05/1987 12/2001 97 15

450 Galveston 3430 Galveston 10 29°20' 94°46' 01/1897 09/2001 92 61

451 Galveston WB Airport 3431 Galveston 5 29°16' 94°52' 07/1948 09/1963 95 16

452 Garcia Lake 3441 Deaf Smith* 4,203 34°53' 103°01' 06/1948 06/1951 28 3

453 Garcia Lake 12 ENE 3442 Deaf Smith 4,134 34°55' 102°44' 07/1965 05/1971 82 7

454 Garden City 3445 Glasscock 2,640 31°51' 101°28' 10/1912 12/2001 97 90

455 Garden City 16 E 3446 Sterling 2,461 31°50' 101°12' 04/1949 09/1951 81 3

456 Garlington Ranch 3462 Sterling* *2,620 31°55' 100°53' 06/1948 08/1948 18 1

457 Garner State Park 3463 Uvalde* 1,401 29°35' 99°44' 07/1948 05/1950 31 3

458 Gary 3472 Panola* 289 32°02' 94°22' 06/1940 01/1958 90 19

459 Gaston 3480 Fort Bend* 102 29°43' 95°44' 09/1947 01/1951 61 5

460 Gatesville 4 SSE 3485 Coryell 760 31°23' 97°43' 02/1900 12/2001 94 95

Table 1. Summary of National Weather Service daily precipitation stations in Texas with known names, latitudes, 

and longitudes—Continued

Seq.

no. NWS station name

NWS

station

no.

County

Elev.

(ft above

NGVD 

29)

LatitudeLongitude

Begining

date

(mm/yyyy)

Ending

date

(mm/yyyy)

Percent

coverage

Years

of

record
42 Atlas of Interoccurrence Intervals for Selected Thresholds of Daily Precipitation in Texas 

461 George West 2 SSW 3508 Live Oak 262 28°18' 98°07' 01/1916 12/2001 98 86

462 Georgetown 3506 Williamson 748 30°38' 97°41' 12/1896 01/1983 90 54

463 Georgetown Lake 3507 Williamson 840 30°41' 97°43' 07/1981 12/2001 97 21

464 Giddings 5 E 3525 Lee 550 30°11' 96°51' 03/1940 12/2001 99 62

465 Gilmer 3547 Upshur* 371 32°44' 94°57' 12/1950 09/1956 77 7

466 Gilmer 4 WNW 3546 Upshur 390 32°44' 95°02' 03/1929 12/2001 98 73

467 Girvin 3557 Pecos 2,313 31°04' 102°24' 09/1947 04/1979 92 33

468 Glade 3564 Tarrant* *589 32°53' 97°06' 06/1948 09/1951 68 4

469 Gladewater 3 WSW 3565 Gregg 244 32°31' 94°57' 09/1946 05/1976 87 31

470 Glen Cove 2 NE 3579 Coleman 2,090 31°52' 99°37' 10/2001 12/2001 25 1

471 Glen Rose 2 W 3591 Somervell 655 32°14' 97°47' 12/1963 09/2000 96 38

472 Glenfawn 3585 Rusk* 351 31°55' 94°51' 05/1949 08/1958 92 10

473 Gold 3605 Gillespie 1,640 30°20' 98°41' 03/1948 12/2001 97 54

474 Goldthwaite 1 WSW 3614 Mills 1,500 31°27' 98°35' 04/1923 12/2001 97 71

475 Goliad 3618 Goliad 142 28°40' 97°24' 09/1912 12/2001 97 90

476 Goliad 1 SE 3620 Goliad 160 28°39' 97°23' 04/1949 12/2001 94 53

477 Goliad 6 NE 3619 Goliad* 151 28°43' 97°20' 07/1948 12/1959 96 12

478 Gonzales 1 N 3622 Gonzales 380 29°32' 97°27' 04/1915 12/2001 99 64

479 Gonzales 10 SW 3624 Gonzales 365 29°26' 97°31' 02/1997 12/2001 98 5

480 Gonzales 2 3623 Gonzales 302 29°30' 97°27' 11/1948 12/1964 91 17

481 Goose Creek 3640 Harris 20 29°44' 94°58' 10/1921 08/1956 96 36

482 Gordon 1 SW 3639 Palo Pinto 1,050 32°32' 98°23' 10/1991 12/2001 92 11

483 Gordonville 3642 Grayson 755 33°47' 96°51' 06/1948 12/2001 87 10

484 Gorman 2 NNE 3646 Eastland 1,380 32°14' 98°39' 09/1951 05/1999 83 9

485 Gouldbusk 3654 Coleman* 1,503 31°33' 99°29' 04/1948 02/1954 33 7

486 Graham 3668 Young 1,050 33°06' 98°35' 01/1897 12/2001 96 99

487 Granbury 2 ENE 3673 Hood 722 32°27' 97°45' 12/1943 09/1975 90 32

488 Grandfalls 3 SSE 3680 Ward 2,425 31°18' 102°49' 02/1909 11/2001 89 87

489 Granger 3685 Williamson 584 30°43' 97°26' 02/1968 12/2001 94 34

490 Granger Dam 3686 Williamson 565 30°42' 97°20' 07/1980 12/2001 97 22

491 Grapeland 3689 Houston* 479 31°29' 95°29' 09/1935 04/1975 87 40

492 Grapevine Dam 3691 Tarrant 585 32°57' 97°03' 01/1897 12/2001 95 72

493 Greenville KGVL Radio 3734 Hunt 545 33°10' 96°06' 03/1900 12/2001 97 101

494 Groesbeck 3770 Limestone 469 31°31' 96°32' 12/1963 08/1975 90 13

495 Groveton 3778 Trinity 350 31°04' 95°08' 07/1923 12/2001 87 64

496 Gruver 3787 Hansford 3,170 36°15' 101°24' 07/1941 12/2001 97 61

497 Guadalupe Pass CAA Airport 3789 Culberson 5,452 31°50' 104°48' 06/1948 08/1950 74 3

498 Gunter 5 S 3822 Collin 735 33°22' 96°46' 02/1948 11/2000 98 53

499 Guthrie 3828 King 1,740 33°37' 100°19' 09/1947 12/2001 92 53

500 Guyer 3831 Wilbarger 1,161 34°08' 98°56' 06/1948 09/1951 79 4

501 Hackberry 3841 Cottle 1,670 33°56' 100°08' 05/1971 12/1987 82 17

502 Hagansport 3846 Franklin 360 33°20' 95°14' 12/1909 12/2001 94 89

503 Hale Center 3862 Hale* 3,432 34°05' 101°51' 01/1897 11/1957 88 19

504 Hale Center 14 WNW 3864 Hale* 3,533 34°08' 102°03' 12/1946 05/1958 78 13

505 Hall Ranch 3871 Kerr 2,280 30°08' 99°36' 06/1948 09/1951 73 4

506 Hallettsville 2 N 3873 Lavaca 275 29°28' 96°56' 01/1897 12/2001 98 104

507 Hallsville 1 W 3877 Harrison 250 32°30' 94°35' 03/1998 12/2001 95 4

508 Hamilton 2 E 3884 Hamilton 1,260 31°42' 98°05' 08/1915 12/2001 91 48

509 Hamlin 1 SW 3890 Jones 1,720 32°52' 100°07' 10/1910 12/2001 93 75

510 Happy 3922 Swisher* 3,622 34°44' 101°51' 06/1941 11/1947 82 7

511 Harleton 3941 Harrison 345 32°41' 94°34' 05/1949 12/2001 96 53

512 Harlingen 3943 Cameron 38 26°12' 97°40' 05/1911 12/2001 97 89

Table 1. Summary of National Weather Service daily precipitation stations in Texas with known names, latitudes, 

and longitudes—Continued

Seq.

no. NWS station name

NWS

station

no.

County

Elev.

(ft above

NGVD 

29)

LatitudeLongitude

Begining

date

(mm/yyyy)

Ending

date

(mm/yyyy)

Percent

coverage

Years

of

record
Table 1 43

513 Harper 3954 Gillespie 2,080 30°18' 99°15' 10/1909 12/2001 96 61

514 Harris Lake 3963 Brazoria *43 29°15' 95°33' 12/1948 01/1949 5 2

515 Hart 3972 Castro 3,640 34°21' 102°05' 01/1947 12/2001 90 49

516 Hart Jones Ranch 3976 Hale* 1,250 34°17' 102°04' 11/1946 07/1954 84 9

517 Hartley 4 ESE 3981 Hartley 3,905 35°51' 102°19' 10/1947 12/2001 97 55

518 Haskell 3992 Haskell 1,600 33°09' 99°44' 08/1897 12/2001 97 104

519 Haskell 6 NW 3994 Haskell* 1,703 33°14' 99°48' 10/1941 07/1963 92 23

520 Haskell SCS 3995 Haskell* 1,552 33°04' 99°37' 09/1946 08/1948 61 3

521 Hawkins 4020 Wood 335 32°34' 95°12' 04/1924 12/2001 90 54

522 Hawley 3 NE 4026 Jones 1,650 32°39' 99°44' 04/1973 09/1994 92 22

523 Haynes Ranch 4033 Blanco 1,371 30°28' 98°25' 03/1948 11/1958 95 11

524 Heath Canyon 4051 Brewster 1,760 29°26' 102°49' 04/1995 12/2001 95 7

525 Heath Farm 4055 Brown* 1,650 31°44' 99°11' 06/1948 06/1948 8 1

526 Hebbronville 4058 Jim Hogg 580 27°19' 98°41' 03/1905 12/2001 93 96

527 Hemphill 4076 Sabine 300 31°21' 93°50' 06/1967 01/1992 91 26

528 Hemphill 6 NE 4077 Sabine 180 31°24' 93°47' 02/1992 12/2001 96 9

529 Hempstead 4080 Waller 249 30°06' 96°05' 09/1946 09/1978 96 33

530 Henderson 4081 Rusk 420 32°10' 94°47' 07/1908 12/2001 99 94

531 Henly 4088 Hays 1,161 30°12' 98°13' 03/1948 11/1965 97 18

532 Henrietta 4093 Clay 930 33°48' 98°12' 06/1897 12/2001 98 101

533 Hereford 4098 Deaf Smith 3,820 34°49' 102°24' 01/1905 12/2001 95 74

534 Hereford 1 SE 4100 Deaf Smith* 3,822 34°49' 102°24' 06/1948 08/1951 67 4

535 Hewitt 4122 McLennan 660 31°28' 97°12' 05/1879 12/2001 99 116

536 Hext 4123 Menard* 1,923 30°52' 99°32' 06/1948 03/1952 14 3

537 Hico 4137 Hamilton 1,025 31°59' 98°01' 11/1910 12/2001 95 92

538 Hidalgo 4139 Hidalgo* 102 26°06' 98°16' 09/1946 03/1955 70 9

539 Higgins 1 N 4140 Lipscomb 2,578 36°08' 100°01' 11/1907 11/2001 95 57

540 Highbank 4150 Falls* 351 31°10' 96°49' 05/1916 07/1949 65 7

541 Hillsboro 4182 Hill 550 32°01' 97°07' 06/1903 12/2001 97 99

542 Hindes 4191 Atascosa 360 28°43' 98°48' 06/1948 09/1951 81 4

543 Hitchland 6 SSW 4196 Hansford 3,192 36°25' 101°21' 10/1947 10/1973 85 27

544 Hondo 4254 Medina 876 29°20' 99°08' 01/1900 12/2001 98 82

545 Hondo Airport 4256 Medina 920 29°21' 99°10' 03/1975 12/2001 92 25

546 Honey Grove 4257 Fannin 680 33°35' 95°54' 04/1898 12/2001 99 87

547 Hords Creek Dam 4278 Coleman 1,942 31°51' 99°34' 07/1953 12/2001 99 49

548 Horger 4280 Jasper 112 31°00' 94°10' 09/1946 12/1982 97 37

549 Hot Springs 4299 Brewster* 2,201 29°11' 103°00' 07/1948 09/1951 60 4

550 Houston Addicks 4309 Harris 91 29°46' 95°39' 06/1948 04/1951 57 4

551 Houston Alief 4311 Harris 71 29°43' 95°36' 06/1948 12/1964 88 17

552 Houston Barker 4313 Harris 127 29°49' 95°44' 06/1948 12/2001 99 54

553 Houston Barker 520 Harris 131 29°49' 95°44' 01/1948 05/1948 42 1

554 Houston Bush International Airport 4300 Harris 95 29°59' 95°21' 06/1969 12/2001 99 33

555 Houston Deer Park 2348 Harris *26 29°43' 95°08' 01/1948 05/1948 40 1

556 Houston Deer Park 4315 Harris 35 29°43' 95°08' 08/1945 12/2001 96 57

557 Houston Fairbanks 3043 Harris 89 29°48' 95°30' 09/1947 05/1948 37 2

558 Houston Fairbanks 4317 Harris 89 29°48' 95°31' 06/1948 03/1954 83 7

559 Houston Golf Crest 4319 Harris 49 29°41' 95°17' 06/1948 05/1950 53 3

560 Houston Heights 4310 Harris 59 29°47' 95°26' 10/1947 05/1948 33 2

561 Houston Heights 4321 Harris 65 29°47' 95°26' 06/1948 12/2001 97 50

562 Houston Hobby Airport 4307 Harris 44 29°38' 95°16' 11/1941 12/2001 93 61

563 Houston Independent Heights 4323 Harris 93 29°52' 95°25' 06/1948 06/1995 96 48

564 Houston Jersey Village 4327 Harris 112 29°53' 95°32' 06/1948 12/2001 96 54

Table 1. Summary of National Weather Service daily precipitation stations in Texas with known names, latitudes, 

and longitudes—Continued

Seq.

no. NWS station name

NWS

station

no.

County

Elev.

(ft above

NGVD 

29)

LatitudeLongitude

Begining

date

(mm/yyyy)

Ending

date

(mm/yyyy)

Percent

coverage

Years

of

record
44 Atlas of Interoccurrence Intervals for Selected Thresholds of Daily Precipitation in Texas 

565 Houston NWSO 4333 Galveston 19 29°28' 95°05' 06/1905 12/2001 79 17

566 Houston San Jacinto Dam 4328 Harris 58 29°55' 95°09' 06/1954 09/1996 95 43

567 Houston Satsuma 4329 Harris 122 29°56' 95°38' 03/1923 12/1964 93 26

568 Houston Spring Branch 4331 Harris 92 29°48' 95°30' 04/1954 12/2000 96 45

569 Houston WB City 4305 Harris* 43 29°46' 95°22' 11/1941 10/1969 87 29

570 Houston-Port 4326 Harris 19 29°45' 95°17' 02/1991 12/2001 90 11

571 Houston-Westbury 4325 Harris 65 29°41' 95°28' 06/1948 12/2001 97 51

572 Huckabay 4343 Erath 1,415 32°20' 98°18' 04/1963 12/2001 94 37

573 Hudspeth River Ranch 4348 Val Verde 1,630 29°59' 101°10' 03/1988 12/2001 98 14

574 Humble 4362 Harris 102 30°00' 95°15' 06/1954 05/1985 95 32

575 Humble Pump Station 5 WNW 4363 Sutton 2,200 30°21' 100°18' 03/1948 12/2001 90 53

576 Hunt 10 W 4375 Kerr 2,095 30°02' 99°31' 01/1992 12/2001 99 10

577 Hunt 3 SW 4374 Kerr 1,870 30°01' 99°21' 09/1947 05/1999 96 53

578 Huntsville 4382 Walker 494 30°43' 95°33' 09/1946 12/2001 98 56

579 Hurst Springs 4390 Coryell 1,030 31°39' 97°43' 04/1963 12/2001 99 39

580 Hurt 4392 Hunt* 679 33°13' 95°58' 06/1948 08/1948 20 1

581 Hyatt 4397 Tyler* 112 30°34' 94°24' 09/1946 10/1953 81 8

582 Hye 4402 Blanco 1,456 30°15' 98°34' 03/1948 12/2001 94 54

583 Imperial 4425 Pecos 2,400 31°16' 102°42' 09/1947 09/1993 94 47

584 Independence Heights 4430 Harris 79 29°52' 95°25' 10/1947 05/1948 33 2

585 Indian Gap 4440 Hamilton 1,575 31°40' 98°25' 09/1947 10/1983 97 37

586 Indian Hot Springs 4443 Hudspeth* 3,704 30°51' 105°20' 08/1947 06/1953 28 4

587 Ingram No. 2 4458 Kerr 1,703 30°04' 99°14' 01/1992 12/2001 100 10

588 Iowa Park Experiment Station 4471 Wichita 981 33°55' 98°39' 07/1940 02/1964 94 25

589 Iron Bridge Dam 4483 Rains 450 32°49' 95°55' 05/1975 12/1993 94 19

590 Itasca 4503 Hill 712 32°10' 97°09' 10/1947 06/1949 34 3

591 Itasca 4505 Hill 710 32°10' 97°09' 01/1992 12/2001 100 10

592 Jacksboro 4517 Jack 1,100 33°14' 98°09' 03/1941 12/2001 99 61

593 Jacksonville 4525 Cherokee 560 31°57' 95°16' 09/1953 12/2001 88 48

594 Jacksonville Experiment Station 4524 Cherokee 659 31°59' 95°17' 09/1947 12/1963 95 17

595 James River Ranch 4538 Mason 1,552 30°32' 99°23' 03/1948 12/1975 90 28

596 Jarrell 4556 Williamson 895 30°49' 97°36' 08/1926 12/2001 94 75

597 Jasper 4563 Jasper 290 30°54' 94°00' 09/1878 12/2001 91 62

598 Jasper 2 E 4564 Jasper* 220 30°55' 93°58' 12/1948 11/1952 57 5

599 Jayton 4570 Kent 2,010 33°15' 100°34' 06/1910 12/2001 90 54

600 Jeddo 3 S 4575 Bastrop 415 29°46' 97°19' 09/1947 12/2001 97 55

601 Jefferson 4577 Marion 199 32°46' 94°20' 11/1903 09/2001 96 92

602 Jewett 4591 Leon 510 31°21' 96°09' 01/1904 01/1991 91 46

603 Joe Pool Lake 4597 Dallas 591 32°38' 96°58' 03/1984 12/2001 94 18

604 Johnson City 4605 Blanco 1,232 30°17' 98°25' 10/1964 12/2001 93 36

605 Johnson Ranch 4608 McCulloch 1,850 31°14' 99°29' 04/1948 12/1965 94 18

606 Jones CB Ranch 4627 Schleicher 2,090 30°49' 100°08' 05/1948 05/1964 85 17

607 Jones MW Ranch 4630 Schleicher* 2,280 30°57' 100°16' 03/1948 11/1958 97 11

608 Jourdanton 4647 Atascosa 518 28°54' 98°32' 06/1916 12/2001 93 62

609 Judkins 4661 Ector* 2,904 31°43' 102°38' 10/1947 09/1955 88 9

610 Junction 4 SSW 4670 Kimble 1,747 30°26' 99°48' 01/1897 12/2001 91 92

611 Junction FAA Airport 4671 Kimble *1,680 30°30' 99°46' 09/1948 06/2001 90 25

612 Juno 4672 Val Verde 1,801 30°09' 101°07' 10/1964 03/1975 82 12

613 Juno 10 NNE 4674 Crockett 2,103 30°17' 101°05' 10/1975 04/1978 47 4

614 Juno 4 S 4675 Val Verde 1,820 30°05' 101°07' 09/1980 05/1999 76 12

615 Justin 4679 Denton 640 33°04' 97°17' 11/2001 12/2001 17 1

616 Kaffie Ranch 4682 Jim Hogg 479 27°05' 98°35' 03/1965 09/1971 86 6

Table 1. Summary of National Weather Service daily precipitation stations in Texas with known names, latitudes, 

and longitudes—Continued

Seq.

no. NWS station name

NWS

station

no.

County

Elev.

(ft above

NGVD 

29)

LatitudeLongitude

Begining

date

(mm/yyyy)

Ending

date

(mm/yyyy)

Percent

coverage

Years

of

record
Table 1 45

617 Kanawha 4688 Red River 515 33°50' 95°15' 05/1996 04/2001 80 6

618 Karnack 6 SW 4693 Harrison 170 32°35' 94°14' 05/1942 05/2000 96 59

619 Karnes City 2 N 4696 Karnes 450 28°54' 97°52' 10/1919 12/2001 95 82

620 Katy 4703 Harris 142 29°47' 95°49' 06/1948 05/1950 64 3

621 Katy City 4704 Harris 153 29°48' 95°49' 04/1952 12/2001 96 47

622 Kaufman 3 SE 4705 Kaufman 420 32°33' 96°16' 10/1901 12/2001 98 101

623 Kempner 4745 Lampasas 925 31°05' 98°00' 05/1963 01/1987 92 22

624 Kendalia 4757 Kendall 1,360 29°57' 98°30' 08/1996 12/2001 89 6

625 Kenedy 1 E 4752 Karnes 279 28°49' 97°51' 08/1948 04/1977 91 30

626 Kennedale 6 SSW 4761 Tarrant 741 32°33' 97°14' 12/1949 01/1981 90 33

627 Kent 5 E 4767 Jeff Davis 4,183 31°04' 104°09' 04/1898 04/1976 79 41

628 Kent 8 SE 4770 Jeff Davis 4,860 31°00' 104°06' 04/1988 12/2001 98 14

629 Kerrville 4780 Kerr 1,640 30°03' 99°09' 01/1897 07/1974 97 75

630 Kerrville 3 NNE 4782 Kerr 1,782 30°04' 99°06' 10/1974 12/2001 97 28

631 Killeen 4791 Bell 801 31°07' 97°42' 01/1912 08/1978 90 33

632 Killeen 3 S 4792 Bell 910 31°04' 97°44' 10/1978 12/2001 90 24

633 Kingsbury 4805 Guadalupe 510 29°41' 97°45' 02/1997 12/2001 93 5

634 Kingston Ranch 4809 Jeff Davis 4,442 30°52' 103°59' 02/1949 01/1952 26 3

635 Kingsville 4810 Kleberg 66 27°31' 97°51' 02/1902 12/2001 89 83

636 Kirbyville 4819 Jasper 200 30°37' 93°55' 01/1929 02/1999 98 58

637 Knapp 2 SW 4841 Scurry 2,290 32°37' 101°09' 08/1931 12/2001 95 70

638 Knox City 4852 Knox 1,532 33°25' 99°49' 06/1935 11/1965 98 31

639 Kopperl 5 NNE 4866 Hill 620 32°08' 97°28' 12/1900 12/2001 79 18

640 Kountze 4878 Hardin 61 30°22' 94°17' 06/1948 12/2001 89 18

641 Kress 4880 Swisher 3,480 34°22' 101°44' 06/1948 09/1951 82 4

642 Kyle SCS 9 4888 Hays 722 30°00' 97°53' 08/1941 05/1942 40 2

643 La Grange 4903 Fayette 357 29°55' 96°52' 06/1910 12/2001 98 92

644 La Joya 4911 Hidalgo 180 26°15' 98°29' 02/1995 12/2001 96 7

645 La Pryor 4920 Zavala 759 28°59' 99°52' 04/1915 12/2001 90 83

646 La Tuna 1 S 4931 El Paso 3,800 31°58' 106°36' 03/1943 12/2001 96 59

647 La Vernia 4934 Wilson* 479 29°22' 98°06' 09/1947 05/1950 62 4

648 Laguna 3 N 4907 Uvalde 1,160 29°27' 100°01' 08/1996 12/2001 87 6

649 Lajitas 4950 Brewster 2,403 29°16' 103°45' 03/1978 11/2001 93 24

650 Lake Abilene 4960 Taylor 1,755 32°13' 99°53' 03/1962 12/2001 98 40

651 Lake Alan Henry 4967 Garza 2,280 33°03' 101°02' 05/1994 12/2001 96 8

652 Lake Bridgeport Dam 4972 Wise 870 33°13' 97°49' 06/1948 12/2001 44 5

653 Lake Coffee Mill 4973 Fannin* 502 33°44' 96°00' 06/1948 09/1951 74 4

654 Lake Colorado City 4974 Mitchell 2,100 32°20' 100°55' 11/1954 03/1993 83 34

655 Lake Dallas 4977 Denton* 522 33°07' 97°02' 10/1947 05/1956 78 10

656 Lake Fork Reservoir 4976 Wood 414 32°49' 95°31' 01/1989 12/2001 100 13

657 Lake Kemp 4982 Baylor 1,167 33°45' 99°08' 04/1962 12/2001 93 34

658 Lake Kickapoo 4978 Archer 1,060 33°40' 98°47' 11/1947 02/1964 87 18

659 Lake Palo Pinto 4979 Palo Pinto 900 32°38' 98°19' 05/1994 12/2001 95 8

660 Lake Ray Hubbard 4914 Kaufman 440 32°48' 96°29' 05/1978 07/1993 82 16

661 Lake Tawakoni 4980 Rains 450 32°49' 95°55' 02/1994 12/2001 97 8

662 Lake Victor 3 W 4981 Burnet 1,401 30°54' 98°14' 03/1948 11/1965 83 18

663 Lamesa 1 SSE 5013 Dawson 2,965 32°43' 101°56' 05/1910 12/2001 97 92

664 Lampasas 5018 Lampasas 1,032 31°04' 98°11' 01/1897 12/2001 98 104

665 Langtry 5048 Val Verde 1,290 29°47' 101°33' 07/1897 12/2001 86 60

666 Langtry 2 5049 Val Verde 1,342 29°48' 101°34' 10/1964 08/1968 71 5

667 Laredo 2 5060 Webb 430 27°34' 99°29' 09/1946 12/2001 94 40

668 Laredo WB Airport 5057 Webb 500 27°32' 99°28' 04/1915 10/1965 89 24

Table 1. Summary of National Weather Service daily precipitation stations in Texas with known names, latitudes, 

and longitudes—Continued

Seq.

no. NWS station name

NWS

station

no.

County

Elev.

(ft above

NGVD 

29)

LatitudeLongitude

Begining

date

(mm/yyyy)

Ending

date

(mm/yyyy)

Percent

coverage

Years

of

record
46 Atlas of Interoccurrence Intervals for Selected Thresholds of Daily Precipitation in Texas 

669 Latex 5081 Panola* 302 32°21' 94°06' 10/1947 05/1963 91 17

670 Latimer Ranch 5086 Cottle 1,950 33°53' 100°23' 04/1971 09/1994 97 24

671 Lavon Dam 5094 Collin 510 33°02' 96°29' 07/1949 12/2001 97 53

672 Lawn 5097 Taylor 1,950 32°08' 99°44' 03/1948 12/2001 98 54

673 Leaday 5109 Coleman* *1,539 31°34' 99°40' 03/1948 12/1965 83 18

674 Leakey 5113 Real 1,622 29°44' 99°45' 02/1997 12/2001 98 5

675 Leakey 2 5114 Real 1,601 29°42' 99°50' 11/1963 01/1971 81 9

676 Leatherwood Ranch 5116 Erath 1,510 32°18' 98°24' 01/1992 12/2001 91 10

677 Lenorah 5158 Martin 2,800 32°18' 101°53' 03/1941 11/2001 94 60

678 Leon Junction 5167 Coryell* 679 31°21' 97°36' 09/1947 08/1948 21 2

679 Levelland 5183 Hockley 3,550 33°35' 102°22' 02/1926 12/2001 94 66

680 Lewisville 5191 Denton* 489 33°03' 97°00' 09/1947 12/1959 92 13

681 Lewisville 2 E 5190 Denton 455 33°03' 96°58' 05/1909 09/1911 77 3

682 Lewisville Dam 3476 Denton 561 33°04' 97°01' 07/1949 12/1963 93 15

683 Lewisville Dam 5192 Denton 556 33°04' 97°00' 02/1964 12/2001 90 37

684 Lexington 5193 Lee 465 30°24' 97°00' 06/1948 12/2001 97 44

685 Liberty 5196 Liberty 35 30°03' 94°47' 05/1904 12/2001 98 98

686 Liberty Hill 5202 Williamson 1,040 30°40' 97°55' 03/1948 11/1965 89 18

687 Ligon Ranch 5211 Llano* 1,401 30°39' 98°34' 03/1948 01/1954 61 7

688 Lillian 5216 Johnson* 751 32°30' 97°11' 09/1947 12/1959 94 13

689 Lillian 3 W 5218 Johnson 745 32°30' 97°14' 03/1981 05/1997 95 17

690 Lindale 5 SE 5228 Smith 551 32°27' 95°22' 02/1931 06/1965 98 35

691 Linden 5229 Cass 415 33°00' 94°22' 03/1948 12/2001 95 53

692 Lipan 5243 Hood 930 32°31' 98°03' 03/1949 12/2001 97 53

693 Lipscomb 5247 Lipscomb 2,450 36°14' 100°16' 06/1948 12/2001 97 54

694 Little Elm 1 NNE 5258 Denton 551 33°10' 96°56' 01/1946 09/1966 95 21

695 Littlefield 5263 Lamb 3,563 33°55' 102°20' 10/1916 01/1966 88 42

696 Littlefield 5265 Lamb 3,505 33°54' 102°19' 07/1966 12/2001 97 36

697 Livingston 2 NNE 5271 Polk 178 30°44' 94°56' 03/1937 12/2001 99 65

698 Llano 5272 Llano 1,020 30°44' 98°39' 12/1896 12/2001 98 105

699 Llano 18 S 5276 Llano 1,380 30°30' 98°44' 09/1997 12/2001 87 5

700 Lockhart 5284 Caldwell 547 29°53' 97°41' 09/1947 12/2001 98 55

701 Lockhart 2 SW 5285 Caldwell 490 29°51' 97°41' 02/1997 12/2001 98 5

702 Loma Alta 5303 Val Verde* 1,923 29°55' 100°46' 10/1947 09/1951 66 5

703 Lometa 5308 Lampasas 1,480 31°13' 98°24' 03/1948 12/1965 72 18

704 London 5312 Kimble 1,695 30°40' 99°34' 06/1948 12/1953 19 6

705 Long Lake 5 SW 5327 Freestone 312 31°37' 95°51' 04/1915 10/1980 95 37

706 Longview 5341 Gregg 330 32°27' 94°44' 01/1902 12/2001 98 100

707 Longview 11 SE 5348 Rusk 407 32°20' 94°39' 09/1975 12/2001 94 27

708 Loop 5351 Gaines 3,245 32°54' 102°25' 08/1948 07/1995 94 47

709 Loop 10 SE 5354 Gaines 3,104 32°52' 102°22' 08/2001 11/2001 16 1

710 Loraine 5358 Mitchell 2,270 32°25' 100°43' 06/1948 09/1951 82 4

711 Lorenzo 5363 Crosby 3,170 33°40' 101°32' 02/1947 08/1995 84 48

712 Los Angeles 4 WSW 5369 La Salle 288 28°26' 99°03' 04/1998 12/2001 92 4

713 Lovelady 5398 Houston 302 31°08' 95°27' 06/1948 10/1986 96 29

714 Lubbock 2 5412 Lubbock* 3,222 33°35' 101°53' 06/1938 05/1939 50 2

715 Lubbock 6 NNE 5408 Lubbock 3,254 33°39' 101°48' 01/1998 12/2001 100 4

716 Lubbock 9 N 5410 Lubbock 3,245 33°41' 101°49' 09/1946 02/1964 91 19

717 Lubbock International Airport 5411 Lubbock 3,254 33°39' 101°49' 03/1911 12/2001 100 91

718 Lufkin 11 NW 5415 Angelina 350 31°25' 94°53' 01/1983 12/2001 99 19

719 Lufkin 2 5427 Angelina 320 31°22' 94°43' 01/1990 12/2001 100 12

720 Lufkin Angelina County Airport 5424 Angelina 288 31°14' 94°45' 11/1906 12/2001 96 95

Table 1. Summary of National Weather Service daily precipitation stations in Texas with known names, latitudes, 

and longitudes—Continued

Seq.

no. NWS station name

NWS

station

no.

County

Elev.

(ft above

NGVD 

29)

LatitudeLongitude

Begining

date

(mm/yyyy)

Ending

date

(mm/yyyy)

Percent

coverage

Years

of

record
Table 1 47

721 Luling 5429 Caldwell 400 29°40' 97°39' 12/1901 12/2001 99 101

722 Luling 12 NE 5430 Caldwell 445 29°50' 97°34' 08/1997 12/2001 88 5

723 Lumberton 5435 Hardin 39 30°15' 94°10' 11/1995 12/2001 88 7

724 Lynxhaven Ranch 5449 Kerr 2,001 29°58' 99°27' 10/1947 02/1976 83 30

725 Lytle 3 W 5454 Medina 722 29°14' 98°50' 12/1976 12/2001 96 26

726 Mabank 4 SW 5461 Henderson 341 32°20' 96°09' 06/1948 09/1951 80 4

727 Madisonville 5477 Madison 252 30°56' 95°54' 09/1918 11/2001 92 75

728 Magnolia 1 W 5496 Montgomery 260 30°13' 95°47' 06/1954 06/1986 91 31

729 Manchaca 5538 Travis 702 30°08' 97°50' 03/1948 12/1965 98 18

730 Manchester 5540 Red River* 400 33°51' 95°08' 11/1948 11/1948 4 1

731 Mansfield 5560 Tarrant 581 32°34' 97°09' 09/1947 10/1964 95 18

732 Mansfield Dam 5561 Travis 551 30°24' 97°55' 06/1944 03/1964 89 21

733 Maple 5570 Cochran* 3,904 33°47' 102°54' 09/1947 02/1949 31 3

734 Marathon 5579 Brewster 4,055 30°12' 103°14' 01/1897 12/2001 93 68

735 Marble Falls 5580 Burnet* 771 30°34' 98°17' 09/1946 01/1952 77 7

736 Marco 5583 McCulloch 1,942 31°06' 99°34' 04/1948 12/1974 82 27

737 Marfa 19 S 5593 Presidio 4,403 30°02' 104°01' 12/1950 10/1961 66 11

738 Marfa 2 5596 Presidio 4,730 30°18' 104°00' 12/1958 12/2001 91 43

739 Marfa CAA Airport 5589 Presidio* 4,859 30°15' 103°53' 06/1907 12/1954 85 16

740 Marfa Charco MR 5591 Jeff Davis* 5,305 30°29' 104°07' 02/1949 09/1951 88 3

741 Marfa Ryan 5594 Presidio* 4,705 30°22' 104°19' 05/1951 09/1951 39 1

742 Marlin 3 NE 5611 Falls 388 31°20' 96°51' 08/1902 12/2001 97 75

743 Marshall 5618 Harrison 352 32°32' 94°21' 07/1908 12/2001 97 94

744 Martin Ranch 5626 Mason 1,332 30°38' 99°10' 03/1948 12/1965 96 18

745 Marys creek 5646 Tarrant 850 32°44' 97°30' 10/1947 10/1973 91 27

746 Mason 5650 Mason 1,430 30°44' 99°14' 11/1941 12/2001 91 61

747 Matador 5658 Motley 2,290 34°01' 100°49' 11/1947 11/2001 97 55

748 Matagorda 2 5659 Matagorda 10 28°41' 95°58' 07/1910 12/2001 98 92

749 Mathis 4 SSW 5661 Jim Wells 138 28°02' 97°52' 07/1964 12/2001 98 38

750 Maud 5667 Bowie 305 33°19' 94°20' 09/1946 12/2001 91 56

751 Maurbro 5670 Jackson 30 28°55' 96°28' 01/1944 01/1966 91 23

752 Maverick Ranger Station 5674 Brewster 2,703 29°17' 103°30' 01/1962 04/1965 83 4

753 Maypearl 5695 Ellis 530 32°19' 97°01' 06/1948 08/1994 79 7

754 McCartney Bridge 5710 Cass 230 33°19' 94°10' 08/1947 09/1954 88 8

755 McCook 5721 Hidalgo 220 26°29' 98°23' 08/1941 12/2001 96 61

756 McDonald Store 5738 Callahan* 1,752 32°12' 99°24' 09/1958 12/1958 18 1

757 McIntosh Ranch 5761 Schleicher* 2,352 30°44' 100°30' 04/1948 11/1965 89 18

758 McKinney 3 S 5766 Collin 595 33°10' 96°37' 04/1903 12/2001 95 93

759 McLean 5770 Gray 2,860 35°14' 100°36' 06/1948 12/2001 96 44

760 McAllen 5701 Hidalgo 100 26°12' 98°15' 06/1941 12/2001 96 61

761 McAllen Miller Airport 5702 Hidalgo 100 26°10' 98°14' 01/1961 12/2001 95 39

762 McCamey 5707 Upton 2,450 31°08' 102°11' 02/1932 12/2001 99 70

763 McCoy 5723 Atascosa 302 28°51' 98°20' 08/1996 11/1999 81 4

764 McGregor 5757 McLennan 723 31°26' 97°24' 03/1910 12/2001 98 92

765 Medina 5742 Bandera 1,705 29°48' 99°15' 01/1966 02/2000 95 35

766 Medina Lake 5746 Medina 1,169 29°30' 98°54' 05/1991 03/2001 67 11

767 Memphis 5821 Hall 2,090 34°43' 100°32' 07/1905 12/2001 95 96

768 Menard 5822 Menard 1,951 30°55' 99°47' 01/1897 12/2001 96 97

769 Menard 13 WNW 5825 Menard 2,201 31°03' 99°57' 04/1959 12/1965 83 7

770 Mentone 2 S 5828 Loving 2,703 31°41' 103°36' 01/1949 01/1974 86 26

771 Menzies Al Ranch 5832 Menard 2,251 31°04' 99°56' 03/1948 03/1959 85 12

772 Menzies Bill Ranch 5833 Edwards* *2,275 30°08' 99°58' 04/1948 09/1948 50 1

Table 1. Summary of National Weather Service daily precipitation stations in Texas with known names, latitudes, 

and longitudes—Continued

Seq.

no. NWS station name

NWS

station

no.

County

Elev.

(ft above

NGVD 

29)

LatitudeLongitude

Begining

date

(mm/yyyy)

Ending

date

(mm/yyyy)

Percent

coverage

Years

of

record
48 Atlas of Interoccurrence Intervals for Selected Thresholds of Daily Precipitation in Texas 

773 Mercedes 5835 Hidalgo* 79 26°08' 97°55' 09/1946 03/1948 47 3

774 Mercedes 6 SSE 5836 Hidalgo 75 26°04' 97°54' 03/1914 12/2001 97 87

775 Mercury 5840 McCulloch 1,440 31°25' 99°10' 09/1949 08/1950 42 2

776 Meridian 5845 Bosque 770 31°56' 97°40' 09/1982 12/2001 96 20

777 Meridian State Park 5847 Bosque 1,028 31°53' 97°42' 04/1963 08/1982 94 20

778 Merrill Ranch 5854 Jeff Davis 5,472 30°32' 104°03' 01/1939 12/1967 92 29

779 Mertzon 5859 Irion 2,229 31°16' 100°49' 01/1941 08/1987 93 47

780 Mexia 5869 Limestone 535 31°41' 96°29' 09/1904 12/2001 99 96

781 Miami 5875 Roberts 2,755 35°42' 100°38' 07/1905 12/2001 98 97

782 Mid City 4 SE 5878 Lamar 490 33°48' 95°30' 12/1970 09/1997 91 28

783 Middlewell 5887 Hartley* 3,802 35°45' 102°11' 10/1947 03/1953 57 7

784 Midkiff 5888 Upton 2,700 31°38' 101°50' 08/1981 02/1996 81 16

785 Midland 4 ENE 5891 Midland 2,740 32°01' 102°01' 08/1947 12/2001 95 55

786 Midland International Airport 5890 Midland 2,862 31°56' 102°11' 06/1948 12/2001 99 54

787 Midlothian 5896 Ellis* 751 32°29' 97°00' 09/1947 10/1964 92 18

788 Midlothian 2 5897 Ellis 750 32°29' 96°59' 08/1997 12/2001 88 5

789 Midway 4 NE 5904 Madison 235 31°04' 95°43' 04/1978 12/2001 95 24

790 Milam 6 ENE 5915 Sabine 200 31°28' 93°45' 03/1948 05/1969 76 8

791 Miller Ranch 5930 San Saba 1,991 30°58' 98°56' 03/1948 02/1966 72 18

792 Mineola 2 5955 Wood 410 32°40' 95°29' 06/1965 08/1966 62 2

793 Mineola 4 S 5954 Smith 370 32°36' 95°29' 09/1946 10/2000 95 55

794 Mineola 8 ENE 5956 Wood 385 32°43' 95°22' 09/1966 10/2000 94 34

795 Mineral Wells FCWOS Airport 5958 Palo Pinto 930 32°46' 98°03' 06/1948 12/2001 95 49

796 Mirando City 5971 Webb 771 27°27' 99°00' 10/1948 11/1963 89 16

797 Mission 4 W 5972 Hidalgo 133 26°13' 98°24' 09/1910 11/1994 93 84

798 Mission Pumping Station 5973 Hidalgo* 131 26°12' 98°19' 06/1948 05/1950 63 3

799 Mobeetie 5987 Wheeler 2,680 35°32' 100°26' 09/1947 03/1974 89 28

800 Moline 5996 Mills 1,385 31°24' 98°19' 10/1947 09/1951 63 5

801 Monahans 5999 Ward 2,585 31°32' 102°54' 06/1959 11/2001 94 43

802 Monahans 1 NW 6000 Ward* 2,631 31°36' 102°54' 02/1900 05/1953 52 8

803 Montague 6014 Montague 1,079 33°40' 97°45' 06/1943 02/1964 91 22

804 Monte Alto 6017 Willacy* 39 26°33' 97°58' 06/1948 05/1950 62 3

805 Montell 6019 Uvalde* 1,302 29°32' 100°01' 09/1912 02/1944 95 33

806 Montgomery 6024 Montgomery 320 30°23' 95°41' 06/1954 12/2001 98 48

807 Morgan 3 WNW 6058 Bosque 740 32°00' 97°36' 05/1965 12/2001 97 37

808 Morgan Mill 6060 Erath 1,030 32°22' 98°10' 03/1949 12/2001 93 53

809 Morse 6070 Hansford 3,180 36°03' 101°28' 09/1941 01/1998 89 57

810 Morton 6074 Cochran 3,760 33°43' 102°45' 05/1935 12/2001 95 59

811 Moscow 6078 Polk 249 30°55' 94°50' 09/1947 04/1969 88 23

812 Moss Ranch 6085 Llano 1,180 30°33' 98°42' 03/1948 07/1997 91 20

813 Mount Enterprise 6099 Rusk* 610 31°58' 94°40' 04/1948 07/1948 23 1

814 Mount Locke 6104 Jeff Davis 6,790 30°42' 104°01' 02/1935 12/2001 100 67

815 Mount Pleasant 6108 Titus 425 33°10' 95°00' 03/1905 12/2001 97 86

816 Mount Vernon 6119 Franklin 480 33°11' 95°13' 05/1966 12/2001 98 36

817 Mountain Creek 6116 Dallas 522 32°43' 96°56' 09/1947 10/1964 95 18

818 Muenster 6130 Cooke 1,005 33°39' 97°22' 09/1947 12/2001 99 55

819 Muleshoe 1 6135 Bailey 3,830 34°14' 102°44' 08/1921 12/2001 98 81

820 Muleshoe 2 6136 Bailey 3,800 34°13' 102°44' 06/1948 09/1951 61 4

821 Muleshoe National Wildlife Refuge 6137 Bailey 3,740 33°57' 102°46' 02/1980 12/2001 99 22

822 Mullin 6140 Mills 1,492 31°35' 98°40' 03/1948 09/2001 97 54

823 Munday 6146 Knox 1,480 33°27' 99°36' 09/1912 12/2001 99 90

824 Munday 5 SSW 6148 Haskell* 1,503 33°23' 99°39' 10/1939 10/1948 73 8

Table 1. Summary of National Weather Service daily precipitation stations in Texas with known names, latitudes, 

and longitudes—Continued

Seq.

no. NWS station name

NWS

station

no.

County

Elev.

(ft above

NGVD 

29)

LatitudeLongitude

Begining

date

(mm/yyyy)

Ending

date

(mm/yyyy)

Percent

coverage

Years

of

record
Table 1 49

825 Murr Ranch 6158 Kimble 2,402 30°41' 100°05' 03/1948 12/1965 65 17

826 Nacogdoches 6176 Nacogdoches 312 31°36' 94°39' 04/1900 05/1973 98 74

827 Nacogdoches 6177 Nacogdoches 435 31°37' 94°38' 06/1948 12/2001 95 30

828 Naples 1 SW 6190 Morris 361 33°11' 94°41' 12/1909 11/1981 97 73

829 Naples 5 NE 6195 Bowie 290 33°14' 94°40' 04/1982 01/1997 92 16

830 Natalia 6205 Medina 712 29°12' 98°51' 08/1909 08/1976 87 41

831 Navarro Mills Dam 6210 Navarro 454 31°57' 96°42' 01/1963 12/2001 99 39

832 Navasota 6211 Grimes* 220 30°23' 96°07' 09/1946 12/1951 80 6

833 Nazareth 6215 Castro* 3,704 34°33' 102°06' 03/1906 03/1911 75 6

834 Neal Ranch 6219 McCulloch* 1,670 31°11' 99°09' 03/1948 12/1959 94 12

835 Negley 4 SSW 6247 Red River 405 33°42' 95°04' 11/1948 12/2001 94 54

836 Nelson Ranch 6257 Kerr 2,125 29°57' 99°31' 07/1962 02/1983 94 22

837 Neuville 6265 Shelby 480 31°39' 94°09' 09/1947 12/2001 93 35

838 New Boston 6270 Bowie 345 33°27' 94°24' 04/1980 12/2001 94 22

839 New Boston 3 W 6271 Bowie 371 33°28' 94°28' 11/1973 12/1979 88 7

840 New Braunfels 6276 Comal 710 29°44' 98°07' 01/1897 12/2001 96 104

841 New Caney 2 E 6280 Montgomery 235 30°08' 95°11' 01/1952 12/2001 99 50

842 New Gulf 6286 Wharton 72 29°16' 95°54' 06/1946 02/1999 95 54

843 New Summerfield 2 W 6335 Cherokee 380 31°59' 95°08' 01/1992 12/2001 98 10

844 Newport 1 SW 6331 Jack 1,060 33°27' 98°01' 10/1947 12/2001 89 54

845 Newton 6339 Newton 190 30°51' 93°46' 01/1966 03/1977 85 12

846 Newton 6341 Newton 150 30°49' 93°44' 01/1980 12/2001 93 19

847 Nix Store 1 W 6367 Lampasas 1,360 31°07' 98°22' 03/1948 12/2001 91 54

848 Nixon 6368 Gonzales 400 29°16' 97°45' 06/1921 12/2001 97 81

849 Nogalus Guard Station 6382 Houston 400 31°16' 95°08' 09/1947 12/1969 88 21

850 Nolan 6385 Nolan* 2,533 32°18' 100°19' 05/1922 03/1926 78 5

851 North Fork Dam 6434 Williamson 883 30°41' 97°43' 07/1980 06/1981 50 2

852 North Galveston 6435 Galveston* *4 29°20' 94°46' 06/1904 08/1905 63 2

853 North Houston 6438 Harris* 110 29°53' 95°31' 09/1947 05/1948 37 2

854 Northfield 6433 Motley 2,070 34°15' 100°36' 05/1948 12/2001 96 54

855 Northington Ranch 6448 Kendall 1,524 29°51' 98°39' 08/1986 12/2001 95 16

856 Notla 3 SE 6477 Ochiltree 2,900 36°06' 100°35' 10/1947 12/2001 95 54

857 Novice 6484 Coleman 1,982 31°59' 99°37' 03/1948 09/1973 96 26

858 Nugent 1 ESE 6494 Jones 1,591 32°41' 99°40' 08/1943 11/1972 96 30

859 O.C. Fisher Dam 6499 Tom Green 1,964 31°28' 100°29' 12/1975 12/2001 95 27

860 O'Donnell 6504 Lynn 3,046 32°58' 101°49' 06/1948 09/1951 83 4

861 Oak Creek Lake 6495 Coke 2,065 32°03' 100°18' 04/1962 12/2001 99 40

862 Oakwood 2 NNE 6496 Freestone 305 31°36' 95°50' 12/1980 12/2001 95 22

863 Oakwood 7 NW 6497 Freestone 335 31°40' 95°55' 10/1980 11/1981 58 2

864 Odessa 6502 Ector 2,910 31°52' 102°21' 09/1950 12/2001 95 52

865 Oilton 6548 Webb 801 27°27' 98°55' 11/1964 03/1971 80 8

866 Old 8 Camp 6666 6615 King 1,790 33°33' 100°11' 10/1973 09/2000 74 10

867 Olney 6636 Young 1,195 33°22' 98°45' 01/1956 12/2001 94 46

868 Olney 5 NNW 6641 Archer 1,184 33°26' 98°46' 05/1941 12/2001 98 61

869 Olton 6644 Lamb 3,610 34°11' 102°08' 04/1928 12/2001 84 60

870 Omaha 2 W 6649 Morris 395 33°11' 94°46' 09/1997 12/2001 86 5

871 One O One Ranch 6654 Brewster* 3,612 30°10' 103°46' 02/1949 10/1949 69 1

872 Oplin near SCS 174 6660 Callahan* 2,001 32°10' 99°31' 11/1926 02/1928 44 3

873 Orange 6664 Orange 10 30°05' 93°44' 01/1905 12/2001 96 67

874 Orange 9 N 6680 Orange 18 30°13' 93°44' 05/1986 12/2001 98 16

875 Orange Dupont 6663 Orange* 10 30°04' 93°45' 11/1948 10/1950 44 3

876 Orange Riverside 6667 Orange* 10 30°06' 93°44' 11/1947 01/1948 8 2

Table 1. Summary of National Weather Service daily precipitation stations in Texas with known names, latitudes, 

and longitudes—Continued

Seq.

no. NWS station name

NWS

station

no.

County

Elev.

(ft above

NGVD 

29)

LatitudeLongitude

Begining

date

(mm/yyyy)

Ending

date

(mm/yyyy)

Percent

coverage

Years

of

record
50 Atlas of Interoccurrence Intervals for Selected Thresholds of Daily Precipitation in Texas 

877 Orson Ranch 6694 Borden* 2,651 32°45' 101°41' 09/1947 12/1948 59 2

878 Overton 6722 Rusk 500 32°16' 94°59' 12/1943 10/1987 95 45

879 Ozona 1 SSW 6734 Crockett 2,340 30°41' 101°12' 06/1948 12/2001 94 54

880 Ozona 8 WSW 6736 Crockett 2,550 30°41' 101°20' 02/1951 09/1951 61 1

881 Paducah 6740 Cottle 1,900 34°00' 100°18' 09/1946 09/2001 96 53

882 Paducah 10 S 6745 Cottle 1,950 33°52' 100°23' 12/1994 12/2001 62 8

883 Paducah 15 S 6742 King 1,815 33°48' 100°18' 04/1971 12/2001 96 31

884 Paducah 2 WNW 6743 Cottle* 1,890 34°02' 100°19' 06/1913 12/1950 98 38

885 Paint Rock 6747 Concho 1,625 31°30' 99°55' 06/1918 07/2001 97 84

886 Palacios Municipal Airport 6750 Matagorda 12 28°43' 96°15' 02/1943 12/2001 99 59

887 Palestine 2 NE 6757 Anderson 465 31°46' 95°36' 01/1930 12/2001 98 70

888 Palo Pinto 6766 Palo Pinto 1,040 32°45' 98°18' 03/1949 12/2001 98 53

889 Pampa 2 6776 Gray 3,150 35°33' 100°58' 04/1964 12/2001 99 38

890 Pampa WB Airport 6775 Gray 3,232 35°32' 100°58' 04/1908 01/1964 87 41

891 Pandale 1 N 6780 Val Verde 1,689 30°10' 101°33' 08/1909 12/2001 89 56

892 Pandale 11 NE 6781 Val Verde 1,665 30°16' 101°27' 12/1981 12/2001 94 21

893 Panhandle 6785 Carson 3,532 35°24' 101°20' 08/1911 12/2001 96 77

894 Panter 6790 Hood* 1,001 32°20' 97°52' 12/1901 10/1917 91 17

895 Panther Junction 6792 Brewster 3,740 29°19' 103°12' 04/1955 12/2001 99 47

896 Paris 6794 Lamar 542 33°40' 95°34' 12/1896 12/2001 97 101

897 Park Springs 6801 Wise* 961 33°24' 97°49' 09/1947 04/1949 17 3

898 Pasadena Houston 6825 Harris* 30 29°43' 95°13' 10/1956 01/1960 66 5

899 Patricia 6836 Dawson* 3,002 32°33' 102°07' 08/1949 01/1953 8 2

900 Pattison 6843 Harris* 171 29°54' 95°50' 09/1947 03/1952 70 6

901 Pearsall 6879 Frio 635 28°53' 99°05' 03/1902 12/2001 95 98

902 Pearsall 9 WNW 6880 Frio 610 28°58' 99°13' 01/1980 01/1983 77 4

903 Pecos 6892 Reeves 2,610 31°25' 103°30' 01/1904 08/2000 96 72

904 Pecos 8 W 6893 Reeves 2,660 31°22' 103°38' 12/2000 12/2001 54 2

905 Penwell 6932 Ector 2,940 31°44' 102°35' 10/1955 12/2001 97 47

906 Perryton 6950 Ochiltree 2,942 36°23' 100°49' 01/1907 12/2001 95 91

907 Perryton 1 WSW 6955 Ochiltree 2,942 36°23' 100°49' 02/1908 02/1908 0 1

908 Perryton 11 WNW 6953 Ochiltree 3,010 36°26' 100°59' 10/1947 12/2001 98 55

909 Perryton 21 S 6952 Ochiltree 2,985 36°06' 100°44' 04/1978 12/2001 96 24

910 Persimmon Gap 6959 Brewster 2,865 29°39' 103°10' 05/1952 12/2001 84 23

911 Persimmon Gap 6 E 6960 Brewster 2,533 29°39' 103°05' 09/1979 05/1985 82 7

912 Pettit 4 NE 6981 Hockley* 3,553 33°44' 102°28' 07/1948 09/1951 21 4

913 Pflugerville 6992 Travis 679 30°26' 97°37' 03/1948 12/1965 98 18

914 Pidcoke 7017 Coryell 800 31°17' 97°53' 01/1992 12/2001 99 10

915 Pierce 1 E 7020 Wharton 105 29°14' 96°11' 05/1904 12/2001 94 98

916 Pilot Point 7028 Denton 690 33°23' 96°57' 09/1947 12/2001 95 55

917 Pine Springs 7044 Culberson 5,609 31°53' 104°48' 01/1939 12/2001 96 22

918 Pineland 7040 Sabine 220 31°14' 93°57' 01/1965 12/2001 97 25

919 Pitchfork Ranch 7060 Dickens 1,945 33°35' 100°31' 05/1971 12/2001 86 31

920 Pittsburg 5 S 7066 Camp 345 32°55' 94°56' 04/1949 12/2001 99 53

921 Placid 7072 McCulloch 1,631 31°19' 99°11' 03/1948 11/1965 66 18

922 Plains 7074 Yoakum 3,675 33°11' 102°49' 01/1925 12/2001 93 67

923 Plainview 7079 Hale 3,370 34°11' 101°42' 09/1908 12/2001 97 94

924 Plainview Radio KKYN 7081 Hale 3,450 34°12' 101°43' 04/2000 12/2001 87 2

925 Plata 7091 Presidio 3,753 29°51' 104°01' 10/1964 02/1977 82 14

926 Pleak 7097 Fort Bend* 79 29°28' 95°47' 06/1948 09/1950 51 3

927 Pleasanton 7111 Atascosa 416 28°57' 98°29' 01/1948 12/2001 81 15

928 Plemons 7116 Hutchinson* 2,802 35°46' 101°20' 09/1906 08/1951 83 25

Table 1. Summary of National Weather Service daily precipitation stations in Texas with known names, latitudes, 

and longitudes—Continued

Seq.

no. NWS station name

NWS

station

no.

County

Elev.

(ft above

NGVD 

29)

LatitudeLongitude

Begining

date

(mm/yyyy)

Ending

date

(mm/yyyy)

Percent

coverage

Years

of

record
Table 1 51

929 Point Comfort 7140 Calhoun 20 28°39' 96°33' 11/1957 12/2001 96 45

930 Polar 7146 Garza 2,352 33°01' 101°04' 09/1947 06/1975 86 29

931 Pontotoc 7164 Mason 1,562 30°55' 98°59' 04/1948 11/1965 83 16

932 Poolville 7165 Parker* 1,230 32°58' 97°52' 11/1947 04/1957 81 11

933 Popham Ranch 7168 Reeves* 3,304 30°53' 103°33' 09/1947 10/1947 17 1

934 Port Aransas 7170 Nueces 12 27°50' 97°03' 03/1986 12/2001 95 16

935 Port Arthur Airport 7174 Jefferson 16 29°57' 94°01' 10/1947 12/2001 98 55

936 Port Arthur City 7172 Jefferson 5 29°54' 93°58' 11/1975 12/2001 96 27

937 Port Arthur WB City 7173 Jefferson 10 29°52' 93°56' 03/1911 12/1967 87 28

938 Port Isabel 7179 Cameron 17 26°04' 97°13' 01/1897 12/2001 96 72

939 Port Lavaca 2 7182 Calhoun 20 28°37' 96°38' 02/1901 02/1988 86 69

940 Port Mansfield 7184 Willacy 9 26°33' 97°25' 02/1958 12/2001 99 44

941 Port O'Connor 7186 Calhoun 5 28°26' 96°25' 04/1948 10/2001 87 52

942 Possum Kingdom Dam 7205 Palo Pinto 902 32°52' 98°26' 01/1939 04/1975 97 37

943 Post 7206 Garza 2,620 33°11' 101°22' 05/1910 12/2001 97 92

944 Post Oak School 7213 Lee 318 30°16' 96°43' 04/1963 05/1981 82 19

945 Poteet 7215 Atascosa 480 29°02' 98°35' 11/1941 12/2001 96 61

946 Poynor 7230 Henderson 531 32°05' 95°35' 09/1947 10/1975 93 29

947 Prade Ranch 7232 Real 2,052 29°54' 99°46' 10/1955 12/2001 90 42

948 Prairie Mountain 7243 Llano 1,448 30°35' 98°53' 06/1948 09/1951 83 4

949 Presidio 7262 Presidio 2,560 29°33' 104°20' 10/1927 12/2001 97 75

950 Prewit Ranch 7268 Reeves* 2,703 31°17' 103°30' 09/1947 04/1948 32 2

951 Price 7271 Rusk 371 32°07' 94°58' 08/1941 11/1975 97 35

952 Priddy 1 NE 7274 Mills 1,470 31°40' 98°29' 01/1984 09/1997 96 14

953 Proctor Reservoir 7300 Comanche 1,221 31°58' 98°30' 06/1963 11/2001 98 39

954 Provident City 7299 Colorado 151 29°17' 96°38' 09/1947 08/1966 95 20

955 Putnam 7327 Callahan 1,591 32°22' 99°11' 03/1911 12/2001 99 91

956 Quanah 5 SE 7336 Hardeman 1,495 34°15' 99°41' 10/1904 12/2001 97 98

957 Quinlan 7358 Hunt 512 32°55' 96°08' 03/1962 11/1974 90 13

958 Quitaque 1 E 7361 Briscoe 2,572 34°22' 101°03' 07/1934 03/1976 82 42

959 Quitman 7363 Wood 375 32°47' 95°26' 05/1948 08/1987 95 40

960 Quitman 2 7365 Wood 413 32°48' 95°26' 10/1999 12/2001 71 3

961 Rainbow 7388 Somervell 648 32°15' 97°42' 09/1946 12/2001 98 56

962 Rancho Escondido 7411 Brewster* 4,803 30°01' 103°46' 09/1947 08/1949 66 3

963 Randolph Field 7422 Bexar 760 29°31' 98°16' 06/1948 09/1951 78 4

964 Ranger 7425 Eastland* 1,430 32°28' 98°41' 09/1946 07/1952 79 7

965 Ranger 7426 Eastland 1,542 32°28' 98°42' 09/1947 10/1975 96 29

966 Rankin 7431 Upton 2,615 31°13' 101°56' 08/1948 10/1984 90 27

967 Ransom Canyon 7433 Lubbock 3,100 33°32' 101°41' 03/1988 12/2001 99 14

968 Ratcliff 7436 Houston* *400 31°23' 95°08' 04/1915 07/1919 87 5

969 Ray Roberts Lake 7463 Denton 600 33°20' 97°03' 04/1984 04/1988 66 5

970 Raymondville 7458 Willacy 31 26°28' 97°48' 10/1910 12/2001 97 92

971 Reagan 7468 Falls* 430 31°18' 96°42' 11/1927 10/1932 79 6

972 Red Bluff Crossing 7480 San Saba 1,235 31°13' 98°35' 06/1948 12/2001 94 54

973 Red Bluff Dam 7481 Reeves 2,800 31°54' 103°55' 10/1939 12/2000 89 60

974 Red Oak 7495 Ellis 600 32°31' 96°48' 11/1964 06/1996 93 33

975 Red Rock 7497 Bastrop 520 29°58' 97°27' 05/1965 12/2000 97 35

976 Red Springs 2 ESE 7499 Baylor 1,370 33°36' 99°23' 06/1948 09/1951 61 4

977 Reeves Station 7528 Sutton* 2,201 30°28' 100°11' 01/1949 07/1952 13 2

978 Refugio 7529 Refugio 49 28°18' 97°17' 01/1948 11/1984 99 37

979 Refugio 2 NW 7533 Refugio 45 28°19' 97°17' 07/1985 12/2001 92 17

980 Refugio 3 SW 7530 Refugio 54 28°17' 97°19' 05/1991 12/2001 88 11

Table 1. Summary of National Weather Service daily precipitation stations in Texas with known names, latitudes, 

and longitudes—Continued

Seq.

no. NWS station name

NWS

station

no.

County

Elev.

(ft above

NGVD 

29)

LatitudeLongitude

Begining

date

(mm/yyyy)

Ending

date

(mm/yyyy)

Percent

coverage

Years

of

record
52 Atlas of Interoccurrence Intervals for Selected Thresholds of Daily Precipitation in Texas 

981 Regency 7531 Mills* *1,241 31°26' 98°49' 06/1948 08/1948 4 1

982 Reiley Ranch 7534 Sutton* 2,451 30°38' 100°15' 04/1948 07/1950 35 3

983 Reklaw 3 NNE 7547 Rusk 331 31°54' 94°59' 09/1958 03/1988 92 31

984 Rendham 7552 Baylor* 1,352 33°35' 99°09' 09/1947 01/1958 81 12

985 Reno 7556 Parker 770 32°57' 97°34' 06/1948 09/1951 83 4

986 Rhineland 7572 Knox* 1,201 33°32' 99°39' 01/1897 09/1907 95 10

987 Ricardo 7580 Kleberg 59 27°25' 97°49' 06/1909 01/1975 92 67

988 Rice 7581 Navarro* 440 32°16' 96°30' 01/1949 10/1956 80 8

989 Richards 7586 Grimes 315 30°32' 95°51' 06/1954 12/2001 94 47

990 Richardson 7588 Collin 675 32°59' 96°45' 02/1948 12/2001 96 53

991 Richland Springs 7593 San Saba 1,380 31°16' 98°56' 03/1948 12/2001 94 54

992 Richmond 7594 Fort Bend 101 29°35' 95°45' 06/1919 12/2001 96 57

993 Riesel 7608 McLennan* 469 31°29' 96°53' 06/1948 05/1952 75 5

994 Riley Ben Ranch 7612 Gillespie 1,631 30°26' 98°49' 03/1948 12/1965 94 18

995 Ringgold 7614 Montague 895 33°49' 97°56' 11/1947 09/1994 94 48

996 Rio Grande City 1 SE 7622 Starr 172 26°23' 98°49' 01/1897 12/2001 94 84

997 Rio Medina 7628 Medina 850 29°26' 98°52' 08/1922 12/2001 94 80

998 Rising Star 1 S 7633 Eastland 1,633 32°04' 98°57' 02/1942 12/2001 97 60

999 Rising Star 5 NNE 7637 Eastland 1,605 32°09' 98°55' 09/1991 12/2001 90 11

1000 Riverside 7651 Walker 240 30°51' 95°24' 04/1915 01/1970 91 27

1001 Roanoke 7659 Denton 655 33°00' 97°13' 08/1947 12/2001 98 55

1002 Roaring Springs 7663 Motley* 2,503 33°54' 100°52' 09/1949 09/1949 4 1

1003 Robert Lee 7669 Coke 1,780 31°54' 100°29' 03/1908 12/2001 96 58

1004 Robstown 7677 Nueces 85 27°47' 97°39' 09/1922 12/2001 90 62

1005 Roby 7678 Fisher 1,982 32°44' 100°23' 01/1897 06/1975 90 65

1006 Rock Island 7693 Colorado* 249 29°32' 96°35' 01/1900 10/1907 97 8

1007 Rock Port 7705 Aransas* 10 28°01' 97°03' 07/1901 12/1958 86 27

1008 Rockdale 7685 Milam 528 30°39' 97°02' 03/1963 12/2001 98 39

1009 Rockland 1 WSW 7700 Jasper 88 31°01' 94°24' 04/1904 06/1979 90 38

1010 Rockport 7704 Aransas 9 28°01' 97°03' 01/1959 12/2001 100 43

1011 Rocksprings 7706 Edwards 2,400 30°00' 100°13' 04/1932 12/2001 89 63

1012 Rocksprings 14 NE 7714 Edwards 2,173 30°09' 100°03' 04/1978 05/1989 74 11

1013 Rocksprings 18 SW 7712 Edwards 1,725 29°47' 100°25' 02/1963 07/1993 96 31

1014 Rocksprings 26 SSW 7717 Edwards 1,690 29°41' 100°25' 08/1995 12/2001 92 7

1015 Rocksprings 5 W 7711 Edwards* 2,392 30°01' 100°18' 03/1955 06/1956 58 2

1016 Rockwall 7707 Rockwall 543 32°56' 96°28' 09/1946 12/2001 98 56

1017 Rockwall 7708 Rockwall* 600 32°56' 96°27' 09/1950 02/1956 73 7

1018 Romayor 1 WSW 7729 Liberty 60 30°26' 94°51' 10/1982 05/1989 83 8

1019 Romero 7730 Hartley* 4,062 35°43' 102°55' 02/1910 04/1936 85 26

1020 Roosevelt 2 E 7735 Kimble 1,962 30°29' 100°02' 03/1948 12/1965 90 18

1021 Roscoe 7743 Nolan 2,380 32°26' 100°31' 06/1935 12/2001 99 67

1022 Rosebud 7744 Falls 405 31°04' 96°58' 07/1965 12/2001 93 29

1023 Rosenberg 7756 Fort Bend* 112 29°33' 95°47' 04/1915 02/1960 84 22

1024 Ross 7768 McLennan 571 31°43' 97°07' 08/1940 10/1975 89 36

1025 Ross Ranch 7769 King 1,660 33°35' 100°01' 04/1971 07/1979 86 9

1026 Rosser 7773 Kaufman 340 32°28' 96°27' 08/1947 12/2001 95 55

1027 Rossville 7779 Atascosa* 561 29°06' 98°41' 06/1907 05/1926 93 20

1028 Rotan 7782 Fisher 1,935 32°51' 100°27' 07/1924 12/2001 96 78

1029 Round Mountain 1 NW 7787 Blanco 1,340 30°26' 98°21' 12/1958 12/2001 97 44

1030 Round Rock 3 NE 7791 Williamson 722 30°32' 97°38' 02/1968 12/2001 99 34

1031 Ruidosa 7 NE 7813 Presidio 3,625 30°02' 104°35' 07/1983 06/1990 87 8

1032 Runge 7836 Karnes 315 28°53' 97°42' 01/1897 12/2001 96 104

Table 1. Summary of National Weather Service daily precipitation stations in Texas with known names, latitudes, 

and longitudes—Continued

Seq.

no. NWS station name

NWS

station

no.

County

Elev.

(ft above

NGVD 

29)

LatitudeLongitude

Begining

date

(mm/yyyy)

Ending

date

(mm/yyyy)

Percent

coverage

Years

of

record
Table 1 53

1033 Rusk 7841 Cherokee 720 31°48' 95°08' 01/1942 12/2001 98 60

1034 Rust Circle Bar Ranch 7852 Tom Green* 2,201 31°12' 100°10' 04/1948 06/1958 59 10

1035 Sabinal 7873 Uvalde 953 29°21' 99°29' 09/1903 12/2001 94 98

1036 Sabine 7875 Jefferson* 20 29°43' 93°52' 12/1898 12/1903 29 5

1037 Saginaw 7887 Tarrant* *736 32°52' 97°22' 03/1900 04/1901 58 2

1038 Salado 7903 Bell* 650 30°57' 97°32' 05/1910 10/1919 95 10

1039 Salt Flat 7920 Hudspeth 3,722 31°44' 105°04' 10/1978 08/1998 91 21

1040 Salt Flat 10 ENE 7921 Culberson 3,891 31°47' 104°54' 01/1959 12/1977 99 19

1041 Salt Flat CAA Airport 7922 Hudspeth* 3,717 31°45' 105°05' 06/1948 12/1957 96 10

1042 Sam Rayburn Dam 7936 Jasper 189 31°03' 94°06' 01/1968 12/2001 100 34

1043 San Angelo 4 NE 7942 Tom Green* 1,903 31°31' 100°23' 08/1953 03/1955 43 3

1044 San Angelo Dam 7940 Tom Green 1,962 31°28' 100°29' 07/1953 11/1975 97 23

1045 San Angelo WSO Airport 7943 Tom Green 1,916 31°21' 100°29' 09/1946 12/2001 98 56

1046 San Antonio 8 NNE 7947 Bexar 788 29°31' 98°27' 05/1997 12/2001 93 5

1047 San Antonio International Airport 7945 Bexar 809 29°31' 98°27' 09/1946 12/2001 99 56

1048 San Antonio Nursery 7948 Bexar* 591 29°18' 98°28' 01/1897 09/1951 87 38

1049 San Antonio Seaworld 8169 Bexar 940 29°27' 98°42' 06/1988 12/2001 96 14

1050 San Augustine 7951 San Augustine 310 31°30' 94°06' 06/1909 12/2001 92 36

1051 San Benito 7952 Cameron 39 26°08' 97°38' 03/1920 06/1975 92 53

1052 San Benito Filter Plant 7953 Cameron* 39 26°08' 97°38' 06/1948 05/1950 66 3

1053 San Bernard Wildlife Refuge 7957 Brazoria 12 28°55' 95°35' 11/1984 12/1987 70 4

1054 San Diego 7969 Jim Wells* 312 27°46' 98°14' 05/1911 06/1911 17 1

1055 San Jacinto 8045 Walker 415 30°37' 95°43' 02/1977 09/1986 91 10

1056 San Juanito 7979 Hidalgo* *142 26°42' 98°14' 05/1909 08/1915 82 7

1057 San Manuel 7981 Hidalgo 75 26°34' 98°07' 06/1948 07/1951 35 4

1058 San Marcos 7983 Hays 612 29°52' 97°55' 12/1896 12/2001 94 103

1059 San Perlita 7990 Willacy* 20 26°30' 97°36' 06/1948 05/1950 65 3

1060 San Saba 7992 San Saba 1,195 31°11' 98°43' 01/1901 02/2000 95 70

1061 San Saba 7 NW 7994 San Saba 1,330 31°17' 98°45' 03/2000 12/2001 90 2

1062 Sanatorium 7997 Tom Green* 2,031 31°37' 100°39' 09/1947 06/1953 81 7

1063 Sanderson 8022 Terrell 2,855 30°08' 102°23' 01/1897 12/2001 95 69

1064 Sanderson 5 NNW 8023 Terrell 3,080 30°12' 102°25' 10/1947 09/1951 68 5

1065 Sandy 2 S 8036 Blanco 1,240 30°20' 98°28' 02/1949 12/1965 98 17

1066 Sanger 8043 Denton 675 33°21' 97°10' 11/1947 07/1999 87 35

1067 Santa Anna 8047 Coleman 1,745 31°44' 99°18' 03/1913 09/1951 50 5

1068 Santa Rosa 8060 Cameron* 49 26°15' 97°50' 06/1948 05/1950 65 3

1069 Santa Rosa 3 WNW 8059 Hidalgo 50 26°16' 97°52' 03/1987 12/2001 99 15

1070 Sarita 7 E 8081 Kenedy 38 27°13' 97°41' 01/1900 12/2001 95 102

1071 Schulenburg 8126 Fayette 374 29°41' 96°54' 09/1947 12/2001 98 55

1072 Scotland 8139 Archer 964 33°40' 98°28' 04/1997 12/2001 91 5

1073 Seagraves 8154 Gaines 3,438 32°57' 102°34' 03/1980 02/1981 29 2

1074 Sealy 8160 Austin 194 29°47' 96°08' 10/1910 12/2001 95 87

1075 Segovia 8183 Kimble 1,860 30°25' 99°40' 10/1958 12/1965 89 8

1076 Seguin 8186 Guadalupe 512 29°35' 97°57' 12/1922 04/1972 97 51

1077 Seguin 1 SSW 8187 Guadalupe 503 29°33' 97°58' 07/1992 12/2001 94 10

1078 Seminole 8201 Gaines 3,340 32°42' 102°32' 08/1922 12/2001 94 80

1079 Seymour 8221 Baylor 1,287 33°35' 99°16' 06/1905 12/2001 96 89

1080 Shaeffer Ranch 8231 Nueces* 190 27°40' 97°45' 09/1901 02/1903 44 3

1081 Shamrock 8235 Wheeler 2,323 35°12' 100°15' 07/1929 09/1987 99 59

1082 Shamrock 2 8236 Wheeler 2,360 35°12' 100°15' 09/1962 12/2001 94 40

1083 Sheffield 8252 Pecos 2,170 30°41' 101°49' 10/1938 12/2001 92 46

1084 Sheperd 2 SW 8265 San Jacinto* 180 30°29' 95°00' 06/1948 09/1951 83 4

Table 1. Summary of National Weather Service daily precipitation stations in Texas with known names, latitudes, 

and longitudes—Continued

Seq.

no. NWS station name

NWS

station

no.

County

Elev.

(ft above

NGVD 

29)

LatitudeLongitude

Begining

date

(mm/yyyy)

Ending

date

(mm/yyyy)

Percent

coverage

Years

of

record
54 Atlas of Interoccurrence Intervals for Selected Thresholds of Daily Precipitation in Texas 

1085 Sherman 8274 Grayson 760 33°42' 96°38' 05/1897 12/2001 98 102

1086 Sherwood 8279 Irion 2,172 31°17' 100°48' 04/1948 12/1965 77 18

1087 Sierra Blanca 2 E 8305 Hudspeth 4,590 31°10' 105°21' 01/1897 12/2001 89 43

1088 Silsbee 4 N 8311 Hardin 180 30°14' 94°11' 11/1995 12/2001 88 7

1089 Silver 8316 Coke* 1,903 32°02' 100°44' 03/1948 06/1952 65 5

1090 Silver Valley 8326 Coleman 1,960 31°58' 99°33' 11/1973 12/2001 96 29

1091 Silverton 8323 Briscoe 3,280 34°27' 101°18' 09/1946 12/2001 96 56

1092 Simms 3 W 8333 Bowie 320 33°21' 94°33' 05/1981 08/1981 34 1

1093 Simms 4 WNW 8335 Bowie 322 33°22' 94°34' 06/1948 10/1973 87 15

1094 Sinton 8354 San Patricio 51 28°02' 97°29' 09/1921 12/2001 92 77

1095 Sisterdale 8358 Kendall 1,400 29°58' 98°43' 08/1996 12/2001 90 6

1096 Slaton 5 SE 8373 Lynn 3,050 33°22' 101°36' 05/1949 12/2001 99 53

1097 Slidell 8378 Wise 985 33°21' 97°23' 09/1947 11/2000 96 54

1098 Sloan 8382 San Saba 1,302 31°09' 98°55' 04/1935 10/1975 99 41

1099 Smith Brothers Ranch 8400 Jeff Davis* *5,274 30°29' 104°06' 06/1948 12/1948 56 1

1100 Smithsons Valley 8414 Comal* 1,302 29°49' 98°20' 12/1946 06/1955 77 10

1101 Smithville 8415 Bastrop 340 30°00' 97°09' 05/1917 12/2001 95 84

1102 Snyder 8433 Scurry 2,335 32°42' 100°54' 05/1911 12/2001 95 91

1103 Socorro 8435 El Paso* 3,661 31°39' 106°17' 04/1918 10/1950 90 32

1104 Somerville 8445 Burleson* 249 30°21' 96°31' 01/1908 09/1951 86 25

1105 Somerville Dam 8446 Burleson 263 30°20' 96°32' 04/1963 12/2001 95 38

1106 Sonora 8449 Sutton 2,138 30°34' 100°39' 12/1902 12/2001 90 68

1107 Sonora Experiment Station 8450 Edwards 2,503 30°16' 100°34' 09/1959 02/1964 73 6

1108 Sour Lake 5 SE 8455 Hardin 33 30°06' 94°20' 08/1948 08/1948 8 1

1109 South Camp 6666 8468 King 1,870 33°30' 100°26' 04/1971 12/2001 80 12

1110 South Padre Island 8487 Cameron 5 26°04' 97°09' 02/1992 12/2001 96 10

1111 Southland 8477 Garza* 3,022 33°22' 101°33' 08/1925 09/1931 88 7

1112 Speaks 2 8519 Lavaca 143 29°16' 96°41' 01/1967 12/2001 94 35

1113 Spearman 8523 Hansford 3,095 36°11' 101°11' 08/1920 12/2001 98 82

1114 Spicewood 8531 Burnet 850 30°29' 98°10' 02/1968 12/2001 98 34

1115 Spinks Ranch 8536 Menard 2,231 30°46' 99°50' 03/1948 03/1964 94 17

1116 Splendora 8538 Montgomery* 161 30°14' 95°10' 09/1947 08/1951 80 5

1117 Spring Branch 2 SE 8544 Comal 1,119 29°51' 98°22' 03/1956 12/2001 98 44

1118 Spring Branch 3 SSW 8541 Comal 1,190 29°50' 98°26' 03/1995 05/1997 73 3

1119 Springtown 8561 Parker 869 32°58' 97°40' 05/1957 03/1978 94 22

1120 Spur 8566 Dickens 2,297 33°28' 100°52' 05/1911 12/2001 97 69

1121 Stamford 1 8583 Jones 1,640 32°56' 99°48' 02/1911 12/2001 94 86

1122 Stamford 2 8584 Jones 1,601 32°57' 99°48' 06/1948 09/1951 70 4

1123 Stephenville 1 N 8623 Erath 1,309 32°14' 98°11' 05/1918 12/2001 93 67

1124 Stephenville 4 NNE 8624 Henderson* 1,421 32°17' 96°12' 03/1969 11/1972 94 4

1125 Stephenville 6 SW 8625 Erath 1,450 32°10' 98°19' 06/1948 11/1968 86 9

1126 Sterley 8628 Floyd* 3,251 34°12' 101°24' 03/1947 02/1960 75 14

1127 Sterling City 8630 Sterling 2,265 31°50' 100°58' 04/1926 12/2001 96 76

1128 Sterling City 8 NE 8631 Sterling 2,710 31°55' 100°52' 06/1949 12/2001 94 28

1129 Sterling City 9 NW 8632 Sterling* 2,402 31°54' 101°08' 07/1949 08/1960 82 12

1130 Stiles 8640 Reagan* 2,904 31°24' 101°28' 04/1916 04/1918 69 3

1131 Stillhouse Hollow Dam 8646 Bell 706 31°02' 97°31' 07/1963 12/2001 97 39

1132 Stinnett 8647 Hutchinson 3,130 35°50' 101°27' 02/1929 02/1944 38 5

1133 Stockdale 4 N 8658 Wilson 475 29°17' 97°58' 12/1940 12/2001 92 30

1134 Stony 8677 Denton* 702 33°14' 97°20' 09/1948 09/1951 47 4

1135 Stowell 8683 Chambers* *20 29°47' 94°23' 06/1911 07/1915 54 4

1136 Stratford 8692 Sherman 3,693 36°20' 102°04' 07/1911 12/2001 95 80

Table 1. Summary of National Weather Service daily precipitation stations in Texas with known names, latitudes, 

and longitudes—Continued

Seq.

no. NWS station name

NWS

station

no.

County

Elev.

(ft above

NGVD 

29)

LatitudeLongitude

Begining

date

(mm/yyyy)

Ending

date

(mm/yyyy)

Percent

coverage

Years

of

record
Table 1 55

1137 Strawn 8 NNE 8696 Palo Pinto 1,180 32°39' 98°28' 03/1949 12/2001 99 53

1138 Study Butte 8713 Brewster* 2,602 29°19' 103°32' 03/1923 12/1929 97 7

1139 Study Butte 8714 Brewster 2,550 29°19' 103°30' 05/1993 12/2001 95 9

1140 Substation 14 8721 Edwards 2,602 30°16' 100°35' 05/1922 12/1952 98 31

1141 Sugar Land 8728 Fort Bend 82 29°37' 95°38' 09/1946 12/2001 98 56

1142 Sulphur Springs 8743 Hopkins 495 33°09' 95°38' 01/1897 12/2001 96 93

1143 Sunray 4 SW 8761 Moore 3,543 35°58' 101°52' 11/1932 08/1984 88 28

1144 Sutherland Springs 8773 Wilson* *416 29°17' 98°03' 06/1910 07/1917 82 8

1145 Sweetwater Avenger 8789 Nolan* 2,392 32°28' 100°28' 11/1916 10/1928 65 6

1146 Tahoka 8818 Lynn 3,120 33°10' 101°47' 03/1913 12/2001 95 77

1147 Talpa 8824 Coleman 1,932 31°46' 99°42' 03/1948 05/1965 94 18

1148 Tampico 8833 Hall 2,251 34°28' 100°49' 08/1947 11/1984 94 38

1149 Tarpley 8845 Bandera 1,404 29°40' 99°17' 10/1937 12/2001 94 35

1150 Tascosa 8852 Oldham 3,412 35°34' 102°18' 09/1947 07/1984 97 38

1151 Tatum 8859 Rusk 269 32°18' 94°31' 06/1948 09/1951 78 4

1152 Taylor 8861 Williamson 565 30°34' 97°24' 01/1929 08/2001 99 73

1153 Taylor 1 NW 8862 Williamson 571 30°35' 97°24' 09/2000 12/2001 67 2

1154 Taylor Ranch 8863 San Saba 2,003 30°57' 98°56' 03/1966 12/2001 99 36

1155 Teague 8874 Freestone* *512 31°38' 96°17' 10/1913 06/1917 75 5

1156 Teague Ranch 8877 Gillespie 1,630 30°25' 98°48' 03/1966 12/2001 99 36

1157 Telegraph 8897 Kimble 1,721 30°19' 99°54' 03/1948 12/2001 93 53

1158 Telephone 8898 Fannin 541 33°47' 96°01' 09/1947 01/1958 81 12

1159 Temple 8910 Bell 635 31°05' 97°19' 01/1897 12/2001 97 104

1160 Temple 3 SE 8911 Bell* 650 31°03' 97°21' 06/1948 10/1952 77 5

1161 Tennyson 8920 Coke 1,962 31°44' 100°18' 03/1948 12/1965 87 18

1162 Terlingua 8924 Brewster* 2,592 29°18' 103°33' 06/1948 09/1951 83 4

1163 Terlingua Ranch 8926 Brewster 3,680 29°27' 103°23' 05/1993 12/2001 96 9

1164 Terrell 8929 Kaufman 515 32°46' 96°17' 10/1947 12/2001 95 55

1165 Tesco 8939 Nolan 2,001 32°30' 100°15' 09/1944 12/1971 97 28

1166 Texarkana 8942 Bowie 390 33°25' 94°05' 10/1968 12/2001 97 34

1167 Texarkana Dam 8944 Cass 282 33°18' 94°10' 12/1955 07/1974 92 20

1168 Texline 8964 Dallam* *4,419 36°25' 102°50' 08/1904 08/1912 76 9

1169 Theodore 8979 Winkler* *2,856 31°51' 103°10' 05/1910 09/1913 85 4

1170 Thompsons 3 WSW 8996 Fort Bend 72 29°29' 95°38' 02/1942 12/2001 92 49

1171 Thorndale 9001 Milam 475 30°37' 97°12' 02/1968 12/2001 99 34

1172 Thornton 1 SSE 9004 Limestone 475 31°23' 96°34' 09/1947 12/2001 96 55

1173 Three Rivers 9009 Live Oak 151 28°28' 98°11' 05/1922 12/1987 99 66

1174 Three Rivers 8 NE 9007 Live Oak 250 28°34' 98°08' 01/1988 12/2001 99 14

1175 Throckmorton 9014 Throckmorton 1,370 33°10' 99°11' 01/1924 09/1999 98 76

1176 Throckmorton 7 NE 9016 Throckmorton 1,230 33°17' 99°06' 03/2000 12/2001 89 2

1177 Throckmorton 8 NNW 9013 Throckmorton *1,393 33°18' 99°13' 01/1960 02/1964 78 5

1178 Thurber 5 NE 9015 Palo Pinto 964 32°32' 98°20' 07/1910 02/1991 90 54

1179 Tilden 4 SSE 9031 McMullen 345 28°24' 98°31' 11/1903 12/2001 89 54

1180 Tilden 9 S 9030 McMullen 246 28°19' 98°34' 06/1997 12/2001 92 5

1181 Tinnin Ranch 9037 Reeves* 3,232 31°19' 103°59' 06/1948 09/1951 82 4

1182 Toledo Bend Dam 9068 Newton 190 31°10' 93°33' 07/1975 12/2001 98 27

1183 Tomball 9076 Harris 210 30°06' 95°37' 09/1946 12/2001 96 56

1184 Tornillo 2 SSE 9088 El Paso 3,525 31°24' 106°03' 09/1946 12/2001 92 24

1185 Tow 3 SE 9099 Llano 1,050 30°51' 98°26' 04/1978 12/2001 98 24

1186 Town Bluff Dam 8568 Tyler 210 30°48' 94°11' 08/1953 01/1970 92 18

1187 Town Bluff Dam 9101 Tyler 214 30°48' 94°11' 02/1970 12/2001 98 32

1188 Toyah 9106 Reeves 2,812 31°18' 103°48' 09/1947 02/1977 91 30

Table 1. Summary of National Weather Service daily precipitation stations in Texas with known names, latitudes, 

and longitudes—Continued

Seq.

no. NWS station name

NWS

station

no.

County

Elev.

(ft above

NGVD 

29)

LatitudeLongitude

Begining

date

(mm/yyyy)

Ending

date

(mm/yyyy)

Percent

coverage

Years

of

record
56 Atlas of Interoccurrence Intervals for Selected Thresholds of Daily Precipitation in Texas 

1189 Trent 2 SSW 9122 Taylor 1,925 32°27' 100°07' 01/1948 12/2001 97 54

1190 Trenton 9125 Fannin 760 33°23' 96°20' 10/1947 12/2001 95 55

1191 Tri City Airport 9129 Hidalgo* 200 26°24' 98°21' 06/1948 05/1950 66 3

1192 Trickham 9132 Coleman 1,401 31°35' 99°13' 03/1948 12/1965 99 18

1193 Trinidad 1 SW 9136 Henderson 239 32°08' 96°06' 01/1915 04/1966 91 23

1194 Trinidad Power Plant 9137 Henderson 292 32°08' 96°06' 05/1966 03/1990 91 25

1195 Trinity 9139 Trinity* 230 30°57' 95°23' 05/1900 05/1907 76 8

1196 Troup 9147 Smith* 469 32°09' 95°07' 07/1913 01/1931 93 19

1197 Troy 9153 Bell 700 31°12' 97°17' 09/1947 12/2001 99 55

1198 Truby 3 ESE 9154 Jones 1,713 32°38' 99°53' 09/1947 08/1972 95 26

1199 Trunk 9162 Martin* 2,533 32°13' 101°43' 01/1948 01/1949 49 2

1200 Truscott 3 W 9163 Knox 1,571 33°45' 99°51' 09/1948 12/2001 92 43

1201 Tuco Station 9169 Hale* 3,353 33°53' 101°51' 12/1946 10/1952 75 7

1202 Tulia 9175 Swisher 3,470 34°31' 101°45' 05/1947 12/2001 97 55

1203 Tulia 6 NE 9176 Swisher* 3,504 34°36' 101°42' 01/1897 11/1952 84 51

1204 Turkey 9191 Hall 2,330 34°23' 100°53' 10/1947 12/2001 90 47

1205 Tyler 9207 Smith 550 32°18' 95°17' 03/1984 12/2001 99 18

1206 Tyler 5 NE 9214 Smith 489 32°24' 95°16' 01/1955 01/1984 97 30

1207 Tyler Pounds Field 9213 Smith 544 32°21' 95°24' 07/1898 11/1954 84 20

1208 Umbarger 9224 Randall 3,746 34°57' 102°06' 10/1947 12/2001 97 55

1209 Upland 9248 Upton* 2,602 31°23' 102°00' 08/1948 08/1948 7 1

1210 Utopia 9260 Uvalde 1,338 29°35' 99°31' 02/1991 12/2001 92 11

1211 Uvalde 9265 Uvalde 912 29°13' 99°46' 03/1905 05/1985 95 81

1212 Uvalde 9267 Uvalde* 932 29°14' 99°48' 03/1920 12/1946 98 27

1213 Uvalde 3 SW 9268 Uvalde 920 29°11' 99°49' 08/1985 12/2001 88 17

1214 Uvalde 9 SW 9264 Uvalde 828 29°08' 99°54' 08/1996 08/1998 66 3

1215 Valentine 9270 Jeff Davis 4,430 30°35' 104°30' 06/1978 12/2001 97 24

1216 Valentine 10 WSW 9275 Presidio 4,420 30°33' 104°38' 03/1897 12/2001 96 72

1217 Valley Junction 9280 Robertson 269 30°50' 96°38' 04/1902 12/1977 92 39

1218 Valley Mills 9282 Bosque 630 31°39' 97°28' 01/1992 12/2001 89 10

1219 Valley View 9286 Cooke 725 33°29' 97°09' 09/1947 12/2001 98 55

1220 Van Horn 9295 Culberson 4,065 31°02' 104°50' 01/1939 12/2001 91 63

1221 Vancourt 9304 Tom Green 1,903 31°21' 100°11' 04/1948 12/1965 89 18

1222 Vancourt 5 SW 9307 Tom Green* 1,903 31°21' 100°14' 06/1948 01/1949 31 2

1223 Vanderpool 9311 Bandera 1,601 29°45' 99°34' 08/1978 09/1993 94 16

1224 Vanderpool 10 N 9312 Bandera 2,265 29°48' 99°34' 08/1996 12/2001 90 6

1225 Vanderpool 4 N 9313 Bandera 1,825 29°48' 99°34' 10/1994 12/2001 91 8

1226 Vega 9330 Oldham 4,012 35°15' 102°25' 03/1923 04/1983 98 61

1227 Venus 9337 Johnson 659 32°26' 97°06' 09/1947 10/1964 95 18

1228 Vernon 9346 Wilbarger 1,227 34°09' 99°19' 03/1904 12/2001 95 72

1229 Victoria ASOS 9364 Victoria 115 28°51' 96°55' 07/1961 12/2001 99 41

1230 Victoria CP&D 9365 Victoria 61 28°47' 97°00' 01/1922 12/2001 94 42

1231 Victoria Fire Station No. 5 9361 Victoria 101 28°51' 97°01' 11/1999 12/2001 71 3

1232 Victoria Regional Airport 9367 Victoria 104 28°50' 96°55' 04/1999 12/2001 89 3

1233 Victoria WB Airport 9363 Victoria* 115 28°47' 97°05' 12/1946 06/1961 91 16

1234 Voss 1 WSW 9410 Coleman 1,650 31°37' 99°35' 01/1949 03/1981 93 33

1235 Waco 9421 McLennan* 381 31°32' 97°04' 09/1946 12/1957 94 12

1236 Waco 9415 McLennan 627 31°33' 97°12' 11/1995 12/2001 87 7

1237 Waco Dam 9417 McLennan 495 31°36' 97°13' 03/1965 12/2001 96 37

1238 Waco Regional Airport 9419 McLennan 500 31°36' 97°13' 01/1930 12/2001 100 70

1239 Waelder 7 S 9424 Gonzales 342 29°36' 97°19' 09/1947 02/1993 90 46

1240 Walcott 9435 Deaf Smith 4,114 34°56' 102°59' 06/1971 08/1976 86 6

Table 1. Summary of National Weather Service daily precipitation stations in Texas with known names, latitudes, 

and longitudes—Continued

Seq.

no. NWS station name

NWS

station

no.

County

Elev.

(ft above

NGVD 

29)

LatitudeLongitude

Begining

date

(mm/yyyy)

Ending

date

(mm/yyyy)

Percent

coverage

Years

of

record
Table 1 57

1241 Waller 9448 Waller 143 30°03' 95°56' 09/1947 08/1998 95 52

1242 Walnut Springs 4 ESE 9456 Bosque 860 32°02' 97°42' 05/1963 05/1965 68 3

1243 Warren 2 S 9480 Tyler 110 30°35' 94°24' 05/1935 06/1992 94 51

1244 Washington State Park 9491 Washington 215 30°20' 96°09' 04/1915 12/2001 92 57

1245 Water Valley 9499 Tom Green 2,120 31°40' 100°43' 07/1898 12/2001 94 55

1246 Water Valley 11 ENE 9500 Coke* 2,142 31°42' 100°32' 04/1949 07/1958 63 10

1247 Water Valley 11 NNE 9501 Coke 2,455 31°48' 100°37' 02/1959 12/2001 97 43

1248 Waters Bluff 9503 Smith 504 32°31' 95°07' 11/2001 12/2001 17 1

1249 Watson 9504 Burnet 1,005 30°55' 98°01' 02/1968 12/2001 99 34

1250 Waxahachie 9522 Ellis 630 32°25' 96°51' 05/1897 12/2001 97 104

1251 Wayside 9527 Armstrong 3,400 34°47' 101°32' 06/1948 09/1951 76 4

1252 Weatherford 9532 Parker 955 32°44' 97°46' 01/1902 12/2001 97 100

1253 Webb 9538 Tarrant* 650 32°42' 97°04' 09/1947 12/1959 94 13

1254 Weimar 9549 Colorado* *416 29°42' 96°47' 02/1902 09/1903 62 2

1255 Welder Wildlife Foundation 9559 San Patricio 50 28°06' 97°25' 10/1964 12/2001 97 38

1256 Wellington 9565 Collingsworth 2,040 34°50' 100°12' 04/1912 12/2001 90 62

1257 Weslaco 2 E 9588 Hidalgo 75 26°09' 97°58' 09/1947 12/2001 97 55

1258 West 9593 McLennan 642 31°48' 97°06' 05/1952 12/2001 90 11

1259 Westway 9646 Deaf Smith* *3,933 34°49' 102°34' 09/1947 08/1948 31 2

1260 Wharton 9655 Wharton 111 29°18' 96°05' 05/1902 12/2001 90 66

1261 Wheeler 9662 Wheeler 2,495 35°26' 100°16' 04/1979 12/2001 97 23

1262 Wheelock 9665 Robertson 420 30°54' 96°23' 06/1948 09/1951 79 4

1263 White Oak 1 WSW 9709 Gregg 315 32°30' 94°53' 08/2000 12/2001 71 2

1264 White River Reservoir 9711 Crosby 2,412 33°27' 101°05' 10/1997 12/2001 85 5

1265 Whitehouse 2 SE 9708 Smith 515 32°12' 95°12' 01/1992 12/2001 94 10

1266 Whitney Dam 9715 Bosque 574 31°51' 97°22' 10/1949 12/2001 98 53

1267 Whitsett 9717 Live Oak 258 28°39' 98°15' 10/1964 12/2001 97 38

1268 Whitsett 3 SW 9716 Live Oak 210 28°38' 98°16' 05/1914 09/1964 96 49

1269 Wichita Falls 10th Street 9727 Wichita 924 33°55' 98°32' 07/1940 07/1940 1 1

1270 Wichita Falls 5 SW Airport 9723 Wichita 988 33°54' 98°33' 01/1996 12/2001 100 6

1271 Wichita Falls WSO Airport 9729 Wichita 1,030 33°58' 98°29' 01/1897 12/2001 95 101

1272 Wichita Valley 55 9732 Wichita* 991 33°56' 98°37' 05/1939 03/1954 68 16

1273 Wichita Valley Farm 29 9730 Wichita 961 33°56' 98°35' 04/1939 08/1972 90 29

1274 Wiergate 9734 Newton* 180 31°01' 93°43' 08/1925 08/1943 89 19

1275 Wildwood 9754 Tyler 200 30°31' 94°26' 02/1992 12/2001 99 10

1276 William Harris Reservoir 9772 Brazoria 39 29°15' 95°33' 01/1949 04/1964 94 16

1277 Willis 9780 Montgomery* *348 30°26' 95°29' 01/1907 01/1928 64 11

1278 Wills Point 9800 Van Zandt 522 32°42' 96°01' 04/1905 12/2001 97 82

1279 Wilson 9809 Lynn* 3,202 33°20' 101°42' 07/1942 08/1946 82 5

1280 Wilson Ranch 9813 Bandera* 2,280 29°54' 99°36' 09/1947 06/1962 92 16

1281 Wimberley 1 NW 9815 Hays 830 30°00' 98°03' 11/1984 12/2001 94 18

1282 Wimberley 2 9814 Hays 1,112 29°58' 98°04' 03/1984 10/1984 67 1

1283 Winchell 1 WNW 9816 Brown 1,381 31°29' 99°11' 03/1948 01/1965 80 18

1284 Winfield 9826 Franklin* 479 33°09' 95°08' 01/1910 10/1936 99 27

1285 Wink FAA Airport 9830 Winkler 2,807 31°46' 103°12' 06/1938 12/2001 96 60

1286 Winnsboro 6 SW 9836 Wood 429 32°53' 95°20' 10/1947 12/2001 91 55

1287 Winter Haven Experiment 9842 Dimmit 600 28°38' 99°52' 09/1947 02/1964 91 18

1288 Winters 1 NNE 9847 Runnels 1,862 31°58' 99°57' 08/1968 12/2001 97 34

1289 Winters 9 NNE 9845 Taylor 1,972 32°06' 99°54' 07/1911 06/1968 86 44

1290 Witt Ranch 9853 Nolan 2,090 32°29' 100°18' 01/1972 11/1975 98 4

1291 Wolf Creek Dam 9858 Ochiltree 2,703 36°14' 100°40' 06/1948 09/1951 83 4

1292 Wolfe City 9859 Hunt 660 33°21' 96°04' 09/1947 12/2001 98 55

Table 1. Summary of National Weather Service daily precipitation stations in Texas with known names, latitudes, 

and longitudes—Continued

Seq.

no. NWS station name

NWS

station

no.

County

Elev.

(ft above

NGVD 

29)

LatitudeLongitude

Begining

date

(mm/yyyy)

Ending

date

(mm/yyyy)

Percent

coverage

Years

of

record
58 Atlas of Interoccurrence Intervals for Selected Thresholds of Daily Precipitation in Texas 

1293 Woodsboro 9892 Refugio* 49 28°14' 97°20' 08/1916 07/1964 95 49

1294 Woodson 9893 Throckmorton 1,263 33°01' 99°03' 06/1948 12/2001 87 16

1295 Woodville 9896 Tyler* 230 30°47' 94°26' 04/1917 02/1919 58 3

1296 Woodville 9898 Tyler 283 30°46' 94°24' 09/1988 12/2001 83 14

1297 Worlds End Ranch 9904 Kerr 1,923 29°58' 99°26' 04/1976 08/1983 93 8

1298 Wortham 9912 Freestone 495 31°47' 96°27' 01/1992 01/1996 81 5

1299 Wright Patman Dam and Lake 9916 Cass 282 33°18' 94°10' 08/1974 12/2001 95 28

1300 WTU Lake Pauline 9935 Hardeman 1,503 34°15' 99°41' 12/1978 05/1979 25 2

1301 Yoakum 9952 Lavaca 325 29°16' 97°07' 07/1917 12/2001 95 80

1302 Yorktown 9953 DeWitt 260 28°58' 97°31' 10/1947 12/2001 93 55

1303 Young 9959 Freestone* *348 31°51' 96°05' 09/1947 08/1948 40 2

1304 Youngsport 9962 Bell 735 30°57' 97°43' 01/1992 12/2001 100 10

1305 Ysleta 9966 El Paso 3,670 31°41' 106°19' 02/1939 12/2001 98 63

1306 Zapata 3 SW 9976 Zapata 320 26°52' 99°15' 01/1909 12/2001 87 47

Table 1. Summary of National Weather Service daily precipitation stations in Texas with known names, latitudes, 

and longitudes—Continued

Seq.

no. NWS station name

NWS

station

no.

County

Elev.

(ft above

NGVD 

29)

LatitudeLongitude

Begining

date

(mm/yyyy)

Ending

date

(mm/yyyy)

Percent

coverage

Years

of

record
Table 2 59

Table 2 Table 2. National Weather Service daily precipitation stations in Texas, by county—Continued

County

no.

County

name

Station sequence no.

(table 1)

County

no.

County

name

Station sequence no.

(table 1)

1 Anderson 435, 887 49 Cooke 387, 448, 449, 818, 1219

2 Andrews 29 50 Coryell 260, 261, 262, 269, 391, 407, 460, 579, 678, 

914

3 Angelina 718, 719, 720 51 Cottle 202, 501, 670, 881, 882, 884

4 Aransas 35, 36, 37, 1007, 1010 52 Crane 279, 280

5 Archer 38, 350, 658, 868, 1072 53 Crockett 6, 95, 613, 879, 880

6 Armstrong 230, 1251 54 Crosby 286, 711, 1264

7 Atascosa 212, 542, 608, 763, 927, 945, 1027 55 Culberson 497, 917, 1040, 1220

8 Austin 84, 1074 56 Dallam 156, 240, 254, 299, 1168

9 Bailey 819, 820, 821 57 Dallas 190, 303, 304, 305, 388, 603, 817

10 Bandera 765, 1149, 1223, 1224, 1225, 1280 58 Dawson 663, 899

11 Bastrop 70, 197, 378, 600, 975, 1101 59 DeWitt 292, 293, 1302

12 Baylor 657, 976, 984, 1079 60 Deaf Smith 114, 452, 453, 533, 534, 1240, 1259

13 Bee 83, 167 61 Delta 256

14 Bell 86, 631, 632, 1038, 1131, 1159, 1160, 1197, 

1304

62 Denton 323, 324, 615, 655, 680, 681, 682, 683, 694, 

916, 969, 1001, 1066, 1134

15 Bexar 229, 380, 963, 1046, 1047, 1048, 1049 63 Dickens 331, 919, 1120

16 Blanco 103, 295, 523, 582, 604, 1029, 1065 64 Dimmit 42, 100, 189, 196, 1287

17 Borden 447, 877 65 Donley 226

18 Bosque 234, 235, 281, 776, 777, 807, 1218, 1242, 1266 66 Duval 87, 88, 252, 438

19 Bowie 315, 750, 829, 838, 839, 1092, 1093, 1166 67 Eastland 187, 357, 484, 964, 965, 998, 999

20 Brazoria 22, 30, 128, 437, 514, 1053, 1276 68 Ector 609, 864, 905

21 Brazos 150, 242, 243 69 Edwards 17, 238, 772, 1011, 1012, 1013, 1014, 1015, 

1107, 1140

22 Brewster 18, 115, 195, 222, 257, 524, 549, 649, 734, 

752, 871, 895, 910, 911, 962, 1138, 1139, 

1162, 1163

70 El Paso 271, 272, 369, 371, 393, 394, 646, 1103, 1184, 

1305

23 Briscoe 958, 1091 71 Ellis 52, 67, 385, 404, 753, 787, 788, 974, 1250

24 Brooks 398 72 Erath 203, 344, 345, 572, 676, 808, 1123, 1125

25 Brown 104, 147, 166, 525, 1283 73 Falls 540, 742, 971, 1022

26 Burleson 168, 244, 1104, 1105 74 Fannin 110, 546, 653, 1158, 1190

27 Burnet 92, 137, 163, 164, 662, 735, 1114, 1249 75 Fayette 408, 643, 1071

28 Caldwell 700, 701, 721, 722 76 Fisher 1005, 1028

29 Calhoun 929, 939, 941 77 Floyd 415, 416, 1126

30 Callahan 55, 288, 289, 756, 872, 955 78 Foard 290

31 Cameron 78, 146, 512, 938, 1051, 1052, 1068, 1110 79 Fort Bend 79, 237, 277, 459, 926, 992, 1023, 1141, 1170

32 Camp 920 80 Franklin 502, 816, 1284

33 Carson 893 81 Freestone 396, 705, 862, 863, 1155, 1298, 1303

34 Cass 45, 691, 754, 1167, 1299 82 Frio 327, 332, 440, 901, 902

35 Castro 334, 335, 515, 833 83 Gaines 708, 709, 1073, 1078

36 Chambers 26, 1135 84 Galveston 450, 451, 565, 852

37 Cherokee 19, 330, 593, 594, 843, 1033 85 Garza 651, 930, 943, 1111

38 Childress 215, 216, 217, 218 86 Gillespie 188, 270, 338, 436, 473, 513, 994, 1156

39 Clay 211, 532 87 Glasscock 148, 454

40 Cochran 733, 810 88 Goliad 475, 476, 477

41 Coke 861, 1003, 1089, 1161, 1246, 1247 89 Gonzales 85, 213, 343, 478, 479, 480, 848, 1239

42 Coleman 159, 241, 470, 485, 547, 673, 857, 1067, 1090, 

1147, 1192, 1234

90 Gray 759, 889, 890

43 Collin 31, 198, 400, 442, 498, 671, 758, 990 91 Grayson 321, 322, 483, 1085

44 Collingsworth 1256 92 Gregg 469, 706, 1263

45 Colorado 169, 246, 954, 1006, 1254 93 Grimes 27, 82, 832, 989

46 Comal 155, 182, 183, 184, 395, 406, 840, 1100, 1117, 

1118

94 Guadalupe 633, 1076, 1077

47 Comanche 247, 310, 953 95 Hale 1, 361, 503, 504, 516, 923, 924, 1201

48 Concho 253, 276, 358, 359, 386, 885 96 Hall 135, 767, 1148, 1204

Table 2. National Weather Service daily precipitation stations in Texas, by county 
60 Atlas of Interoccurrence Intervals for Selected Thresholds of Daily Precipitation in Texas 

97 Hamilton 508, 537, 585 141 Lamb 695, 696, 869

98 Hansford 496, 543, 809, 1113 142 Lampasas 7, 623, 664, 703, 847

99 Hardeman 220, 259, 956, 1300 143 Lavaca 506, 1112, 1301

100 Hardin 640, 723, 1088, 1108 144 Lee 107, 333, 403, 464, 684, 944

101 Harris 77, 294, 481, 550, 551, 552, 553, 554, 555, 

556, 557, 558, 559, 560, 561, 562, 563, 564, 

566, 567, 568, 569, 570, 571, 574, 584, 620, 

621, 853, 898, 900, 1183

145 Leon 153, 201, 602

102 Harrison 507, 511, 618, 743 146 Liberty 233, 685, 1018

103 Hartley 127, 206, 208, 300, 301, 302, 517, 783, 1019 147 Limestone 494, 780, 1172

104 Haskell 518, 519, 520, 824 148 Lipscomb 112, 113, 307, 418, 539, 693

105 Hays 340, 531, 642, 1058, 1281, 1282 149 Live Oak 223, 461, 1173, 1174, 1267, 1268

106 Hemphill 177, 178, 446 150 Llano 151, 194, 687, 698, 699, 812, 948, 1185

107 Henderson 44, 726, 946, 1124, 1193, 1194 151 Loving 770

108 Hidalgo 360, 384, 538, 644, 755, 760, 761, 773, 774, 

797, 798, 1056, 1057, 1069, 1191, 1257

152 Lubbock 714, 715, 716, 717, 967

109 Hill 34, 126, 541, 590, 591, 639 153 Lynn 860, 1096, 1146, 1279

110 Hockley 679, 912 154 Madison 149, 727, 789

111 Hood 283, 487, 692, 894 155 Marion 601

112 Hopkins 1142 156 Martin 677, 1199

113 Houston 285, 491, 713, 849, 968 157 Mason 186, 595, 744, 746, 931

114 Howard 5, 98, 99, 420 158 Matagorda 74, 75, 748, 886

115 Hudspeth 263, 320, 370, 422, 586, 1039, 1041, 1087 159 Maverick 356, 368

116 Hunt 249, 493, 580, 957, 1292 160 McCulloch 125, 174, 337, 405, 605, 736, 775, 834, 921

117 Hutchinson 116, 117, 928, 1132 161 McLennan 282, 535, 764, 993, 1024, 1235, 1236, 1237, 

1238, 1258

118 Irion 68, 445, 779, 1086 162 McMullen 4, 171, 287, 1179, 1180

119 Jack 33, 592, 844 163 Medina 328, 544, 545, 725, 766, 830, 997

120 Jackson 362, 363, 364, 751 164 Menard 170, 444, 536, 768, 769, 771, 1115

121 Jasper 390, 548, 597, 598, 636, 1009, 1042 165 Midland 785, 786

122 Jeff Davis 62, 106, 219, 352, 421, 627, 628, 634, 740, 

778, 814, 1099, 1215

166 Milam 162, 172, 308, 1008, 1171

123 Jefferson 80, 81, 935, 936, 937, 1036 167 Mills 200, 474, 800, 822, 952, 981

124 Jim Hogg 11, 526, 616 168 Mitchell 245, 654, 710

125 Jim Wells 14, 15, 749, 1054 169 Montague 111, 119, 419, 803, 995

126 Johnson 20, 21, 160, 161, 231, 232, 688, 689, 1227 170 Montgomery 255, 296, 728, 806, 841, 1116, 1277

127 Jones 32, 509, 522, 858, 1121, 1122, 1198 171 Moore 185, 207, 346, 347, 1143

128 Karnes 225, 399, 619, 625, 1032 172 Morris 297, 828, 870

129 Kaufman 278, 622, 660, 1026, 1164 173 Motley 411, 747, 854, 1002

130 Kendall 65, 108, 248, 379, 624, 855, 1095 174 Nacogdoches 221, 339, 826, 827

131 Kenedy 40, 1070 175 Navarro 267, 268, 309, 443, 831, 988

132 Kent 599 176 Newton 109, 845, 846, 1182, 1274

133 Kerr 175, 336, 505, 576, 577, 587, 629, 630, 724, 

836, 1297

177 Nolan 102, 850, 1021, 1145, 1165, 1290

134 Kimble 134, 351, 610, 611, 704, 825, 1020, 1075, 1157 178 Nueces 10, 66, 101, 138, 209, 264, 265, 414, 934, 1004, 

1080

135 King 71, 72, 90, 348, 499, 866, 883, 1025, 1109 179 Ochiltree 154, 401, 856, 906, 907, 908, 909, 1291

136 Kinney 123, 124 180 Oldham 9, 122, 1150, 1226

137 Kleberg 392, 635, 987 181 Orange 329, 873, 874, 875, 876

138 Knox 91, 638, 823, 986, 1200 182 Palo Pinto 129, 482, 659, 795, 888, 942, 1137, 1178

139 La Salle 76, 273, 274, 275, 433, 712 183 Panola 93, 192, 458, 669

140 Lamar 41, 326, 782, 896 184 Parker 13, 932, 985, 1119, 1252

Table 2. National Weather Service daily precipitation stations in Texas, by county—Continued

County

no.

County

name

Station sequence no.

(table 1)

County

no.

County

name

Station sequence no.

(table 1)
Table 2 61

185 Parmer 118, 441 220 Tarrant 39, 89, 140, 298, 354, 355, 389, 427, 428, 429, 

430, 431, 468, 492, 626, 731, 745, 1037, 

1253

186 Pecos 57, 58, 152, 205, 425, 426, 467, 583, 1083 221 Taylor 2, 3, 650, 672, 1189, 1289

187 Polk 266, 697, 811 222 Terrell 341, 342, 1063, 1064

188 Potter 24, 165 223 Terry 144, 145

189 Presidio 94, 139, 157, 179, 409, 737, 738, 739, 741, 

925, 949, 1031, 1216

224 Throckmorton 1175, 1176, 1177, 1294

190 Rains 381, 589, 661 225 Titus 815

191 Randall 181, 1208 226 Tom Green 224, 859, 1034, 1043, 1044, 1045, 1062, 1221, 

1222, 1245

192 Reagan 96, 97, 258, 1130 227 Travis 46, 47, 48, 49, 50, 729, 732, 913

193 Real 176, 284, 674, 675, 947 228 Trinity 495, 1195

194 Red River 53, 120, 227, 228, 617, 730, 835 229 Tyler 581, 1186, 1187, 1243, 1275, 1295, 1296

195 Reeves 60, 61, 63, 64, 903, 904, 933, 950, 973, 1181, 

1188

230 Upshur 465, 466

196 Refugio 51, 978, 979, 980, 1293 231 Upton 762, 784, 966, 1209

197 Roberts 781 232 Uvalde 105, 236, 457, 648, 805, 1035, 1210, 1211, 

1212, 1213, 1214

198 Robertson 132, 434, 1217, 1262 233 Val Verde 25, 56, 191, 250, 251, 316, 317, 318, 319, 402, 

573, 612, 614, 665, 666, 702, 891, 892

199 Rockwall 1016, 1017 234 Van Zandt 180, 365, 382, 1278

200 Runnels 59, 1288 235 Victoria 1229, 1230, 1231, 1232, 1233

201 Rusk 472, 530, 707, 813, 878, 951, 983, 1151 236 Walker 432, 578, 1000, 1055

202 Sabine 143, 204, 527, 528, 790, 918 237 Waller 529, 1241

203 San Augustine 141, 142, 1050 238 Ward 69, 488, 801, 802

204 San Jacinto 239, 1084 239 Washington 133, 1244

205 San Patricio 1094, 1255 240 Webb 383, 423, 439, 667, 668, 796, 865

206 San Saba 210, 214, 417, 791, 972, 991, 1060, 1061, 

1098, 1154

241 Wharton 306, 366, 367, 842, 915, 1260

207 Schleicher 311, 349, 372, 373, 374, 375, 376, 424, 606, 

607, 757

242 Wheeler 8, 16, 799, 1081, 1082, 1261

208 Scurry 637, 1102 243 Wichita 158, 377, 588, 1269, 1270, 1271, 1272, 1273

209 Shackelford 12 244 Wilbarger 500, 1228

210 Shelby 199, 837 245 Willacy 804, 940, 970, 1059

211 Sherman 1136 246 Williamson 28, 412, 462, 463, 489, 490, 596, 686, 851, 

1030, 1152, 1153

212 Smith 353, 410, 690, 793, 1196, 1205, 1206, 1207, 

1248, 1265

247 Wilson 413, 647, 1133, 1144

213 Somervell 471, 961 248 Winkler 1169, 1285

214 Starr 173, 397, 996 249 Wise 23, 121, 136, 312, 313, 314, 652, 897, 1097

215 Stephens 130, 131 250 Wood 521, 656, 792, 794, 959, 960, 1286

216 Sterling 54, 193, 455, 456, 1127, 1128, 1129 251 Yoakum 325, 922

217 Stonewall 43 252 Young 486, 867

218 Sutton 575, 977, 982, 1106 253 Zapata 1306

219 Swisher 510, 641, 1202, 1203 254 Zavala 73, 291, 645

Table 2. National Weather Service daily precipitation stations in Texas, by county—Continued

County

no.

County

name

Station sequence no.

(table 1)

County

no.

County

name

Station sequence no.

(table 1)
62 Atlas of Interoccurrence Intervals for Selected Thresholds of Daily Precipitation in Texas 

Table 3 Table 3. Summary of interoccurrence intervals for daily precipitation thresholds of 0.05 and 0.10 inch—Continued

Seq.

no.

Daily precipitation threshold of 0.05 inch and greater Daily precipitation threshold of 0.10 inch and greater

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue

1 7.93 2,461 19,514 24624508 2.192 .986 .014 10.07 1,937 19,514 19604211 2.843 .998 .002

2 7.27 33 240 3818 -.357 .361 .361 9.23 26 240 2995 -.354 .362 .362

3 7.65 2,577 19,720 25885412 1.648 .950 .050 9.40 2,099 19,720 21095151 1.530 .937 .063

4 8.96 939 8,416 3969846 .249 .598 .402 10.51 801 8,416 3367935 -.039 .484 .484

5 10.82 1,755 18,993 16569638 -.421 .337 .337 12.23 1,553 18,993 14861685 .526 .700 .300

6 10.48 336 3,522 605347 .733 .768 .232 12.36 285 3,522 512981 .647 .741 .259

7 7.49 1,103 8,264 4766073 2.631 .996 .004 8.67 953 8,264 4064079 1.715 .957 .043

8 8.84 165 1,458 107617 -2.343 .010 .010 9.92 147 1,458 94206 -2.539 .006 .006

9 7.67 377 2,893 519681 -1.582 .057 .057 9.30 311 2,893 433373 -1.120 .132 .132

10 6.69 32 214 3809 1.102 .865 .135 7.13 30 214 3637 1.262 .896 .104

11 12.54 488 6,120 1537352 1.129 .871 .129 13.30 460 6,120 1470385 1.657 .951 .049

12 7.42 4,798 35,581 87180863 2.561 .995 .005 8.75 4,066 35,581 72910815 .877 .810 .190

13 5.99 2,507 15,005 18824756 .074 .529 .471 7.05 2,128 15,005 16068381 .516 .697 .303

14 7.13 4,204 29,966 60175440 -5.016 0 0 8.95 3,347 29,966 48747253 -2.799 .003 .003

15 8.14 210 1,709 168503 -1.531 .063 .063 10.89 157 1,709 123164 -1.778 .038 .038

16 12.30 10 123 351 -2.351 .009 .009 17.57 7 123 228 -2.156 .016 .016

17 13.67 9 123 485 -.643 .260 .260 15.38 8 123 402 -.896 .185 .185

18 8.57 3,214 27,539 46058927 4.002 1.000 0 10.98 2,509 27,539 35481609 2.345 .991 .010

19 5.21 3,694 19,240 37460618 5.701 0 0 5.99 3,212 19,240 32259190 4.320 1.000 0

20 7.70 795 6,122 2486368 1.061 .856 .144 7.78 787 6,122 2439636 .618 .732 .268

21 6.12 863 5,279 2221163 -1.267 .103 .103 6.99 755 5,279 1965508 -.652 .257 .257

22 5.34 6,469 34,541 117468023 7.164 0 0 6.12 5,646 34,541 101424478 5.226 0 0

23 7.24 164 1,187 94883 -.559 .288 .288 8.36 142 1,187 82893 -.339 .367 .367

24 7.55 2,607 19,693 26021080 1.210 .887 .113 9.59 2,053 19,693 20460777 .955 .830 .170

25 9.32 1,476 13,756 10157913 .039 .516 .484 11.91 1,155 13,756 7932570 -.085 .466 .466

26 4.79 6,494 31,099 102905232 2.663 .996 .004 5.54 5,612 31,099 88186068 1.371 .915 .085

27 5.66 3,675 20,787 38229396 .092 .536 .464 6.53 3,183 20,787 32944918 -.406 .342 .342

28 6.42 1,874 12,022 11451285 1.243 .893 .107 7.34 1,639 12,022 9947026 .676 .750 .250

29 10.39 1,529 15,884 12076351 -.374 .354 .354 12.37 1,284 15,884 10180781 -.102 .459 .459

30 4.75 6,662 31,631 103919613 -1.937 .026 .026 5.55 5,701 31,631 92565250 3.483 1.000 0

31 5.78 3,136 18,129 28744197 1.085 .861 .139 6.71 2,702 18,129 24718610 .832 .797 .203

32 7.99 2,085 16,648 18406056 4.787 1.000 0 9.16 1,817 16,648 15669485 2.659 .996 .004

33 7.10 3,266 23,183 39449795 4.162 1.000 0 8.25 2,810 23,183 33776561 3.395 1.000 0

34 5.70 636 3,622 1112562 -1.488 .068 .068 6.80 533 3,622 936091 -1.209 .113 .113

35 6.92 1,487 10,292 7872696 1.925 .973 .027 8.24 1,249 10,292 6703624 2.631 .996 .004

36 6.11 1,814 11,081 9991839 -.430 .334 .334 7.39 1,499 11,081 8297856 -.059 .476 .476

37 6.45 1,693 10,911 9157563 -.607 .272 .272 7.86 1,389 10,911 7514678 -.537 .296 .296

38 7.14 3,141 22,410 35977500 2.159 .985 .015 8.39 2,672 22,410 30695035 2.259 .988 .012

39 6.15 3,177 19,535 31243041 .666 .747 .253 7.24 2,697 19,535 26704580 1.235 .892 .109

40 7.88 1,318 10,379 7361988 4.801 1.000 0 8.93 1,162 10,379 6448159 4.092 1.000 0

41 5.72 4,335 24,787 55746924 4.290 1.000 0 6.34 3,912 24,787 49991076 3.369 1.000 0

42 8.65 86 744 29522 -1.240 .108 .108 10.78 69 744 24496 -.657 .256 .256

43 8.75 3,666 32,082 61513214 4.827 1.000 0 10.11 3,172 32,082 52400880 2.912 .998 .002

44 5.97 3,290 19,656 32857724 1.609 .946 .054 6.89 2,855 19,656 28673716 2.028 .979 .021

45 5.09 3,724 18,947 34223115 -3.164 .001 .001 5.78 3,278 18,947 30529406 -1.676 .047 .047

46 5.96 4,338 25,853 56518846 .903 .817 .183 7.37 3,510 25,853 45649991 .629 .735 .265

47 6.55 971 6,363 3145239 .978 .836 .164 8.03 792 6,363 2615098 1.845 .967 .033

48 6.34 891 5,648 2477823 -.788 .215 .215 7.96 710 5,648 1985970 -.439 .330 .330

Table 3. Summary of interoccurrence intervals for daily precipitation thresholds of 0.05 and 0.10 inch

[--, not available, no events that equal or exceed the threshold were observed] 
Table 3 63

49 3.87 78 302 12428 0.844 .801 .199 4.79 63 302 10332 1.184 .882 .118

50 6.58 139 915 68916 1.710 .956 .044 7.69 119 915 58621 1.450 .926 .074

51 6.65 2,741 18,223 25954431 3.558 1.000 0 7.69 2,370 18,223 22071710 1.864 .969 .031

52 6.29 2,084 13,109 13296456 -2.102 .018 .018 6.92 1,895 13,109 12405016 -.096 .462 .462

53 4.31 71 306 10724 -.187 .426 .426 5.02 61 306 8878 -.660 .255 .255

54 21.75 4 87 152 -.438 .331 .331 21.75 4 87 152 -.438 .331 .331

55 10.00 987 9,865 5306619 4.898 1.000 0 10.78 915 9,865 4819279 3.553 1.000 0

56 9.50 251 2,385 319682 1.867 .969 .031 11.52 207 2,385 260043 1.332 .909 .091

57 12.01 1,630 19,579 17132779 5.153 0 0 14.58 1,343 19,579 13811232 3.205 .999 .001

58 13.51 45 608 14119 .373 .645 .355 13.82 44 608 13514 .119 .547 .453

59 8.17 4,432 36,226 82007431 2.486 .994 .006 9.62 3,767 36,226 68352938 .189 .575 .425

60 8.94 47 420 10065 .235 .593 .407 11.67 36 420 8155 .818 .793 .207

61 9.75 2,859 27,865 38069113 -4.101 0 0 12.55 2,220 27,865 30339933 -1.557 .060 .060

62 11.47 19 218 2590 1.892 .971 .029 12.82 17 218 2344 1.892 .971 .029

63 15.93 128 2,039 143852 2.006 .978 .022 16.18 126 2,039 141684 2.002 .977 .023

64 18.44 16 295 2049 -.913 .181 .181 24.58 12 295 1610 -.542 .294 .294

65 6.59 1,126 7,422 3932579 -3.422 0 0 8.09 918 7,422 3268796 -2.124 .017 .017

66 7.43 314 2,334 330773 -2.987 .001 .001 8.91 262 2,334 280944 -2.275 .011 .011

67 5.62 2,373 13,340 16172284 1.836 .967 .033 6.80 1,961 13,340 13333499 1.487 .932 .068

68 10.82 484 5,237 1370231 3.093 .999 .001 12.77 410 5,237 1133652 1.962 .975 .025

69 15.81 311 4,917 781886 .691 .755 .245 16.90 291 4,917 733819 .760 .776 .224

70 8.56 121 1,036 73260 3.217 .999 .001 9.09 114 1,036 70380 3.548 1.000 0

71 7.33 104 762 39327 -.132 .447 .447 8.02 95 762 35140 -.492 .311 .311

72 8.46 516 4,366 1085310 -1.436 .076 .076 9.75 448 4,366 952435 -.958 .169 .169

73 10.19 1,227 12,503 7718573 .380 .648 .352 11.04 1,133 12,503 7120291 .307 .621 .379

74 5.42 223 1,208 129674 -.964 .168 .168 6.33 191 1,208 113374 -.413 .340 .340

75 5.05 4,638 23,435 56422912 4.509 1.000 0 6.13 3,822 23,435 46148513 3.262 .999 .001

76 10.04 115 1,154 53059 -3.722 0 0 13.42 86 1,154 39665 -3.223 .001 .001

77 4.89 3,238 15,838 26845916 4.629 1.000 0 5.64 2,807 15,838 22872661 2.659 .996 .004

78 7.96 91 724 34017 .539 .705 .295 10.20 71 724 26762 .602 .726 .274

79 6.63 88 583 27487 1.162 .877 .123 7.11 82 583 25880 1.297 .903 .097

80 4.47 7,967 35,599 146609580 5.234 0 0 5.25 6,784 35,599 124298752 4.191 1.000 0

81 4.42 3,193 14,126 23030041 2.074 .981 .019 5.25 2,691 14,126 19571412 2.670 .996 .004

82 6.58 1,926 12,671 13407260 7.507 0 0 6.83 1,856 12,671 12908453 7.296 0 0

83 6.08 5,860 35,650 104726727 .346 .635 .365 7.69 4,634 35,650 83340279 1.055 .854 .146

84 5.27 1,483 7,812 5806865 .164 .565 .435 6.09 1,283 7,812 4956622 -.678 .249 .249

85 9.14 181 1,655 133693 -2.502 .006 .006 9.30 178 1,655 130778 -2.591 .005 .005

86 5.95 2,430 14,452 18119690 2.726 .997 .003 7.27 1,987 14,452 14976702 3.327 1.000 0

87 9.48 128 1,213 68395 -2.332 .010 .010 11.23 108 1,213 57679 -2.150 .016 .016

88 10.33 1,244 12,853 7520134 -3.625 0 0 11.49 1,119 12,853 6907420 -2.287 .011 .011

89 6.13 3,112 19,069 30547234 2.852 .998 .002 7.36 2,591 19,069 25530702 2.951 .998 .002

90 9.47 675 6,392 1962075 -4.072 0 0 10.07 635 6,392 1872162 -3.383 0 0

91 8.45 1,468 12,411 9335951 1.648 .950 .050 9.61 1,292 12,411 7985028 -.252 .400 .400

92 6.35 1,950 12,385 12032197 -.274 .392 .392 7.31 1,695 12,385 10446036 -.341 .366 .366

93 4.83 440 2,124 463507 -.293 .385 .385 5.46 389 2,124 410401 -.225 .411 .411

94 12.75 191 2,436 229562 -.317 .376 .376 15.72 155 2,436 183334 -.623 .267 .267

95 12.93 80 1,034 39394 -.736 .231 .231 13.97 74 1,034 38226 -.013 .495 .495

96 8.70 1,587 13,801 10515736 -2.743 .003 .003 10.85 1,272 13,801 8426730 -2.468 .007 .007

Table 3. Summary of interoccurrence intervals for daily precipitation thresholds of 0.05 and 0.10 inch—Continued

Seq.

no.

Daily precipitation threshold of 0.05 inch and greater Daily precipitation threshold of 0.10 inch and greater

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue
64 Atlas of Interoccurrence Intervals for Selected Thresholds of Daily Precipitation in Texas 

97 11.40 99 1,129 52226 -1.129 .130 .130 14.86 76 1,129 42391 -0.180 .429 .429

98 9.47 2,012 19,044 19274152 .470 .681 .319 11.41 1,669 19,044 16129172 1.055 .854 .146

99 5.18 22 114 1083 -1.108 .134 .134 7.13 16 114 660 -1.914 .028 .028

100 10.32 2,770 28,580 37988537 -3.673 0 0 12.16 2,350 28,580 32501205 -2.701 .003 .003

101 7.50 1,228 9,211 5476688 -1.920 .027 .027 9.14 1,008 9,211 4607841 -.409 .341 .341

102 8.99 88 791 36775 .920 .821 .179 9.42 84 791 36057 1.355 .912 .088

103 6.14 6,101 37,448 119345206 6.052 0 0 7.28 5,143 37,448 98223961 2.485 .994 .006

104 8.27 759 6,276 2419955 .766 .778 .222 9.61 653 6,276 2078642 .638 .738 .262

105 9.04 1,134 10,246 5737139 -.726 .234 .234 10.66 961 10,246 5028055 1.144 .874 .126

106 6.61 539 3,562 937751 -.930 .176 .176 8.34 427 3,562 755638 -.228 .410 .410

107 6.51 1,151 7,487 4040092 -3.664 0 0 7.35 1,019 7,487 3623938 -2.764 .003 .003

108 5.91 6,323 37,342 121549544 4.075 1.000 0 7.39 5,054 37,342 96741117 3.103 .999 .001

109 4.89 2,949 14,412 21666071 1.839 .967 .033 5.41 2,665 14,412 19538112 1.556 .940 .060

110 5.53 6,278 34,710 110395377 1.815 .965 .035 6.32 5,493 34,710 96304695 1.311 .905 .095

111 6.82 184 1,254 121884 1.327 .908 .092 8.09 155 1,254 101492 .956 .830 .170

112 7.99 2,872 22,955 34209769 3.510 1.000 0 9.40 2,442 22,955 28472541 1.357 .913 .087

113 8.88 271 2,405 278287 -4.164 0 0 10.19 236 2,405 244529 -3.681 0 0

114 11.40 176 2,006 177988 .190 .575 .425 11.87 169 2,006 168739 -.102 .459 .459

115 12.30 1,469 18,062 13268082 .008 .503 .497 16.33 1,106 18,062 9859080 -.745 .228 .228

116 7.95 730 5,805 2064334 -1.204 .114 .114 10.20 569 5,805 1606345 -1.130 .129 .129

117 7.30 2,632 19,214 25735968 1.583 .943 .057 9.21 2,086 19,214 20339143 1.180 .881 .119

118 11.76 86 1,011 48636 1.908 .972 .028 11.89 85 1,011 48092 1.905 .972 .028

119 6.48 4,257 27,586 59482272 1.473 .930 .070 7.52 3,671 27,586 51532805 1.863 .969 .031

120 4.84 3,960 19,175 38617056 1.868 .969 .031 5.59 3,429 19,175 33443992 1.754 .960 .040

121 6.96 2,637 18,359 22825965 -5.072 0 0 8.02 2,289 18,359 20439994 -2.255 .012 .012

122 9.28 931 8,643 4279015 3.359 1.000 0 11.10 779 8,643 3557387 2.742 .997 .003

123 9.65 3,576 34,510 62219012 .865 .806 .194 11.12 3,103 34,510 53839397 .535 .704 .296

124 10.88 694 7,550 3169720 9.577 0 0 12.65 597 7,550 2691866 8.229 0 0

125 7.29 3,256 23,727 39748690 2.869 .998 .002 8.88 2,673 23,727 32723399 2.859 .998 .002

126 5.87 617 3,619 1068792 -1.837 .033 .033 6.73 538 3,619 945995 -1.136 .128 .128

127 9.54 2,032 19,385 21135243 5.709 0 0 10.92 1,775 19,385 18035640 3.527 1.000 0

128 4.68 2,324 10,885 12781824 .881 .811 .189 5.75 1,892 10,885 10366112 .504 .693 .307

129 7.65 2,566 19,634 26133305 3.284 .999 .001 8.51 2,306 19,634 23247355 2.239 .987 .013

130 7.45 3,535 26,350 47786843 2.683 .996 .004 8.80 2,993 26,350 40030294 1.436 .924 .076

131 7.18 106 761 43470 1.387 .917 .083 8.55 89 761 35712 .891 .814 .186

132 5.88 2,390 14,041 17474274 3.509 1.000 0 6.85 2,050 14,041 14909144 2.818 .998 .002

133 4.94 7,355 36,302 134289828 .878 .810 .190 6.18 5,877 36,302 107249897 .718 .763 .237

134 7.56 159 1,202 80655 -3.406 0 0 9.18 131 1,202 66308 -3.128 .001 .001

135 6.83 178 1,216 104594 -.775 .219 .219 7.70 158 1,216 92885 -.721 .236 .236

136 6.41 4,839 31,019 76445773 2.240 .987 .013 7.55 4,111 31,019 64568218 1.409 .920 .080

137 6.08 581 3,532 1021677 -.178 .429 .429 7.52 470 3,532 843558 .613 .730 .270

138 8.55 894 7,647 3095950 -4.882 0 0 10.22 748 7,647 2738524 -2.012 .022 .022

139 14.30 10 143 1014 2.291 .989 .011 14.30 10 143 1014 2.291 .989 .011

140 6.55 197 1,290 123059 -.766 .222 .222 7.59 170 1,290 112428 .572 .716 .284

141 5.09 2,095 10,670 11831750 4.645 1.000 0 5.67 1,882 10,670 10436481 2.964 .998 .002

142 4.62 1,739 8,028 6945195 -.364 .358 .358 5.46 1,470 8,028 5922560 .247 .598 .402

143 5.11 3,515 17,968 32930171 4.395 1.000 0 5.78 3,107 17,968 28708648 2.751 .997 .003

144 9.91 1,390 13,768 9093555 -3.207 .001 .001 11.38 1,210 13,768 7849760 -3.471 0 0

Table 3. Summary of interoccurrence intervals for daily precipitation thresholds of 0.05 and 0.10 inch—Continued

Seq.

no.

Daily precipitation threshold of 0.05 inch and greater Daily precipitation threshold of 0.10 inch and greater

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue
Table 3 65

145 8.95 1,951 17,470 17380454 1.520 .936 .064 11.13 1,569 17,470 13939386 1.172 .879 .121

146 7.56 3,748 28,335 53915703 1.629 .948 .052 9.62 2,945 28,335 42317463 1.339 .910 .090

147 7.43 2,615 19,432 25394257 -.046 .482 .482 8.83 2,200 19,432 21757690 1.454 .927 .073

148 14.91 85 1,267 46014 -2.323 .010 .010 16.04 79 1,267 43517 -2.009 .022 .022

149 10.19 21 214 2513 .940 .826 .174 10.70 20 214 2410 .977 .836 .164

150 5.87 197 1,156 110290 -.764 .223 .223 7.27 159 1,156 89161 -.651 .257 .257

151 7.26 966 7,017 3269573 -1.900 .029 .029 8.75 802 7,017 2699385 -1.995 .023 .023

152 14.25 555 7,906 2194680 .014 .506 .494 15.81 500 7,906 1917227 -1.162 .123 .123

153 6.00 2,415 14,486 17084111 -1.984 .024 .024 6.70 2,161 14,486 15566766 -.439 .330 .330

154 8.06 1,325 10,685 7218681 1.246 .894 .106 9.82 1,088 10,685 5842688 .295 .616 .384

155 6.53 3,376 22,051 36946092 -.746 .228 .228 7.59 2,907 22,051 32070760 .057 .523 .477

156 10.70 1,375 14,709 10100173 -.078 .469 .469 11.94 1,232 14,709 9025592 -.236 .407 .407

157 21.17 6 127 445 .713 .762 .238 21.17 6 127 445 .713 .762 .238

158 6.39 319 2,037 301499 -2.228 .013 .013 7.75 263 2,037 251944 -1.670 .048 .048

159 8.26 2,130 17,595 20011589 5.430 0 0 9.12 1,929 1,7595 17817262 3.796 1.000 0

160 5.74 1,042 5,981 3022774 -1.675 .047 .047 6.91 866 5,981 2527901 -1.218 .112 .112

161 6.30 2,140 13,484 14892449 2.580 .995 .005 7.50 1,798 13,484 12595159 2.866 .998 .002

162 6.47 1,518 9,819 7973765 4.719 1.000 0 7.60 1,292 9,819 6721427 3.714 1.000 0

163 6.58 5,232 34,426 91749387 2.352 .991 .009 7.81 4,409 34,426 77684132 2.716 .997 .003

164 5.13 101 518 25630 -.352 .362 .362 6.40 81 518 20666 -.233 .408 .408

165 7.65 155 1,185 87241 -1.079 .140 .140 9.19 129 1,185 72822 -.929 .176 .176

166 9.34 678 6,331 2423428 5.825 0 0 10.28 616 6,331 2156358 4.551 1.000 0

167 7.74 156 1,207 91620 -.580 .281 .281 9.73 124 1,207 71055 -.974 .165 .165

168 5.40 2,611 14,097 18420381 .081 .532 .468 6.36 2,218 1,4097 15653644 .105 .542 .458

169 5.82 209 1,216 123314 -.741 .230 .230 6.72 181 1,216 108377 -.354 .362 .362

170 7.39 823 6,084 2480639 -.455 .325 .325 9.30 654 6,084 2010443 .467 .680 .320

171 8.49 970 8,233 3994700 .023 .509 .491 9.98 825 8,233 3332516 -.932 .176 .176

172 5.95 5,523 32,834 91894256 1.737 .959 .041 7.06 4,648 3,2834 77315520 1.562 .941 .059

173 10.36 191 1,978 172020 -2.139 .016 .016 11.64 170 1,978 152903 -2.045 .020 .020

174 9.00 687 6,180 2167594 .957 .831 .169 9.90 624 6,180 1953956 .579 .719 .281

175 7.05 197 1,389 118369 -3.278 .001 .001 8.08 172 1,389 111120 -1.585 .057 .057

176 7.37 2,720 20,049 28195689 3.078 .999 .001 9.12 2,198 20,049 22681040 2.385 .991 .009

177 7.98 4,027 32,125 65328568 1.096 .863 .137 9.50 3,382 32,125 54708665 .714 .762 .238

178 8.71 38 331 6247 -.071 .472 .472 9.46 35 331 5616 -.312 .377 .377

179 10.69 1,821 19,460 18351747 2.642 .996 .004 14.32 1,359 19,460 13891374 3.227 .999 .001

180 5.46 3,051 16,672 26399727 3.636 1.000 0 6.28 2,654 16,672 22910142 3.172 .999 .001

181 8.29 3,408 28,238 47461771 -1.378 .084 .084 10.04 2,814 28,238 38549888 -2.731 .003 .003

182 5.46 2,553 13,932 18020285 1.162 .877 .123 6.88 2,025 13,932 14328708 1.230 .891 .109

183 6.49 298 1,934 252517 -3.699 0 0 7.41 261 1,934 228866 -2.608 .005 .005

184 6.81 127 865 56399 .523 .699 .301 7.15 121 865 55013 .976 .835 .165

185 11.66 189 2,204 189774 -2.116 .017 .017 12.97 170 2,204 172302 -1.813 .035 .035

186 13.68 167 2,285 195844 .592 .723 .277 13.93 164 2,285 191102 .442 .671 .329

187 10.17 6 61 149 -.788 .215 .215 10.17 6 61 149 -.788 .215 .215

188 6.80 2,181 1,420 15850767 -1.554 .060 .060 8.23 1,801 14,820 13421885 .421 .663 .337

189 8.72 3,029 26,415 39990439 -.036 .486 .486 11.46 2,305 26,415 30059782 -1.048 .147 .147

190 6.20 3,050 18,911 29037583 .658 .745 .255 7.10 2,665 18,911 25767019 2.016 .978 .022

191 9.37 1,368 12,819 8552565 -1.575 .058 .058 10.70 1,198 12,819 7595699 -.647 .259 .259

192 4.83 3,765 18,176 34589636 1.160 .877 .123 5.58 3,259 18,176 29969988 1.176 .880 .120

Table 3. Summary of interoccurrence intervals for daily precipitation thresholds of 0.05 and 0.10 inch—Continued

Seq.

no.

Daily precipitation threshold of 0.05 inch and greater Daily precipitation threshold of 0.10 inch and greater

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue
66 Atlas of Interoccurrence Intervals for Selected Thresholds of Daily Precipitation in Texas 

193 11.70 1,040 12,164 6320115 -0.046 .482 .482 12.78 952 12,164 5893799 0.958 .831 .169

194 9.92 648 6,429 2042404 -.859 .195 .195 10.25 627 6,429 1987162 -.610 .271 .271

195 11.83 802 9,486 3677676 -1.628 .052 .052 15.89 597 9,486 2801401 -.451 .326 .326

196 10.97 1,313 14,400 9196614 -1.706 .044 .044 12.96 1,111 14,400 7878150 -.874 .191 .191

197 5.71 1,417 8,095 5822057 .986 .838 .162 6.71 1,206 8,095 4997784 1.436 .924 .076

198 6.60 1,919 12,665 11480135 -4.195 0 0 7.26 1,745 12,665 10621743 -2.806 .003 .003

199 4.68 4,881 22,827 58060610 5.107 0 0 5.35 4,267 22,827 50060086 3.156 .999 .001

200 6.66 2,119 14,121 15341909 2.029 .979 .021 7.76 1,819 14,121 13088726 1.413 .921 .079

201 5.20 4,408 22,939 50707231 .340 .633 .367 6.26 3,664 22,939 42608866 1.459 .928 .072

202 7.84 62 486 18148 2.790 .997 .003 9.17 53 486 15484 2.551 .995 .005

203 6.22 2,267 14,090 15471182 -2.581 .005 .005 7.15 1,971 14,090 13777429 -.600 .274 .274

204 5.01 277 1,388 182572 -1.450 .074 .074 5.28 263 1,388 172575 -1.531 .063 .063

205 12.00 32 384 6555 .655 .744 .256 15.36 25 384 5548 1.350 .911 .089

206 9.14 320 2,925 480618 .835 .798 .202 10.45 280 2,925 414178 .331 .630 .370

207 9.21 56 516 14362 -.077 .469 .469 10.53 49 516 12439 -.195 .423 .423

208 8.59 959 8,239 3957175 .089 .536 .464 10.11 815 8,239 3389059 .466 .680 .320

209 7.42 2,061 15,291 15097522 -3.293 .001 .001 8.63 1,772 15,291 13367600 -.970 .166 .166

210 9.07 473 4,292 1042461 1.017 .845 .155 9.76 440 4,292 955122 .419 .662 .338

211 5.95 343 2,040 336523 -1.223 .111 .111 6.99 292 2,040 280097 -1.763 .039 .039

212 7.05 2,032 14,334 14381521 -.975 .165 .165 9.11 1,574 14,334 11120104 -.979 .164 .164

213 6.48 490 3,173 773574 -.188 .425 .425 7.84 405 3,173 647270 .257 .601 .399

214 8.18 142 1,162 79241 -.816 .207 .207 10.56 110 1,162 61739 -.617 .269 .269

215 8.61 93 801 39842 1.164 .878 .122 10.01 80 801 33094 .510 .695 .305

216 7.86 193 1,517 147556 .192 .576 .424 9.79 155 1,517 119226 .304 .620 .380

217 9.42 1,609 15,148 12875893 3.930 1.000 0 10.27 1,475 15,148 11607275 2.594 .995 .005

218 7.62 2,428 18,497 23039413 2.220 .987 .013 9.27 1,995 18,497 18909837 1.925 .973 .027

219 31.00 1 31 24 .950 .829 .171 31.00 1 31 24 .950 .829 .171

220 7.37 3,326 24,501 40220830 -1.285 .099 .099 8.95 2,737 24,501 33189158 -.920 .179 .179

221 4.50 1,048 4,717 2443369 -.643 .260 .260 5.20 907 4,717 2120704 -.450 .326 .326

222 8.29 2,386 19,773 23859518 .970 .834 .166 10.55 1,874 19,773 18831674 1.232 .891 .109

223 6.98 933 6,509 3015930 -.358 .360 .360 8.94 728 6,509 2361118 -.161 .436 .436

224 10.71 571 6,117 1821669 1.784 .963 .037 11.79 519 6,117 1653848 1.653 .951 .049

225 11.37 1,041 11,834 6723888 5.120 0 0 11.81 1,002 11,834 6396733 4.327 1.000 0

226 7.50 4,459 33,447 74875876 .474 .682 .318 9.00 3,718 33,447 61238799 -1.595 .055 .055

227 4.72 254 1,200 152278 -.022 .491 .491 5.61 214 1,200 125152 -.641 .261 .261

228 5.36 6,348 34,037 110807569 3.544 1.000 0 6.03 5,645 34,037 97475810 1.905 .972 .028

229 6.57 1,386 9,110 6401136 .898 .815 .185 8.04 1,133 9,110 5272103 1.257 .896 .104

230 9.02 3,549 32,007 61323009 8.224 0 0 10.22 3,131 32,007 52876924 5.358 0 0

231 6.31 5,245 33,090 88809095 2.935 .998 .002 7.37 4,490 33,090 75173826 1.385 .917 .083

232 6.39 391 2,497 485978 -.153 .439 .439 7.28 343 2,497 438073 .737 .769 .231

233 4.55 3,799 17,281 33380308 1.805 .964 .036 5.37 3,221 17,281 28372080 1.911 .972 .028

234 5.45 190 1,035 92533 -1.406 .080 .080 6.43 161 1,035 79202 -1.086 .139 .139

235 6.03 3,875 23,374 44922901 -.867 .193 .193 7.22 3,238 23,374 37608793 -.609 .271 .271

236 10.88 528 5,743 1312632 -5.343 0 0 12.12 474 5,743 1226256 -3.736 0 0

237 5.06 3,675 18,579 36696513 7.866 0 0 5.93 3,132 18,579 31179914 6.947 0 0

238 11.61 367 4,259 733878 -2.023 .022 .022 12.27 347 4,259 706894 -1.399 .081 .081

239 4.49 3,863 17,330 33485658 .041 .516 .484 5.39 3,214 17,330 28130428 .991 .839 .161

240 10.25 1,273 13,047 7463924 -6.255 0 0 11.64 1,121 13,047 6656851 -5.202 0 0

Table 3. Summary of interoccurrence intervals for daily precipitation thresholds of 0.05 and 0.10 inch—Continued

Seq.

no.

Daily precipitation threshold of 0.05 inch and greater Daily precipitation threshold of 0.10 inch and greater

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue
Table 3 67

241 7.32 5,111 37,406 98119424 3.275 .999 .001 8.58 4,360 37,406 82163986 0.868 .807 .193

242 5.42 3,235 17,517 28410422 .267 .605 .395 6.52 2,686 17,517 23642239 .446 .672 .328

243 5.51 3,751 20,679 38683152 -.274 .392 .392 6.68 3,094 20,679 31915373 -.226 .411 .411

244 5.11 18 92 615 -1.890 .029 .029 6.57 14 92 456 -1.892 .029 .029

245 8.82 2,993 26,383 39643879 .388 .651 .349 10.62 2,485 26,383 32995663 .566 .714 .286

246 5.01 4,002 20,030 42546162 6.742 0 0 6.04 3,319 20,030 34417435 3.535 1.000 0

247 7.01 4,353 30,526 67427562 1.699 .955 .045 8.22 3,715 30,526 57596118 1.665 .952 .048

248 7.62 259 1,974 231904 -2.588 .005 .005 8.47 233 1,974 206590 -2.688 .004 .004

249 6.08 496 3,015 738935 -.453 .325 .325 6.88 438 3,015 666805 .358 .640 .360

250 10.49 708 7,429 2514959 -2.014 .022 .022 13.06 569 7,429 2038119 -1.475 .070 .070

251 12.05 20 241 2213 -.633 .263 .263 15.06 16 241 1612 -1.136 .128 .128

252 9.80 237 2,323 278242 .287 .613 .387 12.42 187 2,323 214620 -.281 .389 .389

253 8.70 161 1,400 119345 1.296 .902 .098 9.79 143 1,400 104303 .870 .808 .192

254 8.71 2,236 19,485 21360543 -1.593 .056 .056 10.53 1,850 19,485 17931352 -.381 .351 .351

255 5.01 3,861 19,333 36795567 -1.519 .064 .064 5.75 3,363 19,333 32634934 .391 .652 .348

256 6.70 2,720 18,213 24180757 -2.148 .016 .016 7.02 2,593 18,213 23238866 -1.398 .081 .081

257 15.20 40 608 13096 .843 .800 .200 19.61 31 608 9508 .086 .534 .466

258 10.34 1,883 19,465 18842362 2.117 .983 .017 12.15 1,602 19,465 15942038 1.559 .940 .060

259 7.81 579 4,519 1307087 -.037 .485 .485 8.95 505 4,519 1121632 -.662 .254 .254

260 7.63 2,892 22,062 33912100 5.870 0 0 8.33 2,650 22,062 30165114 2.846 .998 .002

261 5.92 247 1,461 190859 1.573 .942 .058 6.99 209 1,461 156941 .700 .758 .242

262 7.04 954 6,712 3172907 -.480 .316 .316 7.46 900 6,712 2998625 -.375 .354 .354

263 12.76 1,453 18,538 13840890 1.829 .966 .034 16.05 1,155 18,538 11055612 1.924 .973 .027

264 7.90 1,507 11,901 9101258 1.004 .842 .158 9.58 1,242 11,901 7561348 1.411 .921 .079

265 6.95 2,837 19,723 29222782 4.108 1.000 0 8.76 2,251 19,723 23102988 3.349 1.000 0

266 4.32 767 3,310 1234424 -1.321 .093 .093 5.02 660 3,310 1084983 -.298 .383 .383

267 5.79 6,292 36,415 117128880 3.079 .999 .001 6.69 5,447 36,415 100661895 1.915 .972 .028

268 5.21 701 3,653 1256704 -.848 .198 .198 6.24 585 3,653 1045461 -.903 .183 .183

269 5.72 124 709 45549 .698 .757 .243 6.33 112 709 41061 .627 .734 .266

270 8.74 1,619 14,154 11558776 .615 .731 .269 9.17 1,543 14,154 11022504 .640 .739 .261

271 76.50 2 153 91 -.993 .161 .161 76.50 2 153 91 -.993 .161 .161

272 21.57 7 151 615 .750 .773 .227 25.17 6 151 541 .824 .795 .205

273 9.46 3,357 31,770 55739003 4.541 1.000 0 11.05 2,876 31,770 46877082 2.423 .992 .008

274 9.17 1,241 11,383 7423502 3.113 .999 .001 11.19 1,017 11,383 6243605 4.345 1.000 0

275 9.73 247 2,403 292787 -.365 .357 .357 10.68 225 2,403 265507 -.464 .321 .321

276 8.85 730 6,457 2502378 2.891 .998 .002 10.69 604 6,457 2030139 1.749 .960 .040

277 5.61 200 1,121 109178 -.639 .262 .262 6.75 166 1,121 91194 -.444 .329 .329

278 5.62 2,108 11,840 12477273 -.013 .495 .495 6.56 1,805 11,840 10786728 .696 .757 .243

279 14.06 52 731 21304 1.510 .934 .066 18.74 39 731 15419 .884 .812 .189

280 11.13 1,481 16,485 12247989 .223 .588 .412 13.75 1,199 16,485 10054183 1.040 .851 .149

281 6.79 650 4,415 1505852 2.184 .986 .014 8.04 549 4,415 1261142 1.648 .950 .050

282 5.32 252 1,341 166688 -.371 .355 .355 6.07 221 1,341 145131 -.530 .298 .298

283 6.48 2,997 19,415 30771392 5.469 0 0 7.53 2,577 19,415 26131424 3.920 1.000 0

284 10.81 882 9,535 4042541 -1.987 .023 .023 11.82 807 9,535 3729110 -1.512 .065 .065

285 5.44 5,980 32,536 100690248 4.692 1.000 0 6.21 5,240 32,536 87886658 3.886 1.000 0

286 8.05 4,645 37,369 91752044 6.750 0 0 9.73 3,839 37,369 74769142 4.547 1.000 0

287 8.01 228 1,826 196372 -1.482 .069 .069 9.98 183 1,826 162189 -.686 .246 .246

288 8.75 1,507 13,182 10106541 1.177 .880 .120 9.76 1,350 13,182 8913004 .108 .543 .457

Table 3. Summary of interoccurrence intervals for daily precipitation thresholds of 0.05 and 0.10 inch—Continued

Seq.

no.

Daily precipitation threshold of 0.05 inch and greater Daily precipitation threshold of 0.10 inch and greater

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue
68 Atlas of Interoccurrence Intervals for Selected Thresholds of Daily Precipitation in Texas 

289 8.53 133 1,134 68029 -1.955 .025 .025 10.90 104 1,134 52280 -2.003 .023 .023

290 9.98 3,058 30,511 49042149 4.909 1.000 0 10.70 2,851 30,511 45419354 4.095 1.000 0

291 8.65 2,255 19,511 22427038 1.602 .945 .055 11.36 1,718 19,511 17121989 1.551 .940 .060

292 5.99 366 2,191 378603 -1.847 .032 .032 7.53 291 2,191 304308 -1.342 .090 .090

293 6.05 5,842 35,323 98959919 -5.413 0 0 7.33 4,817 35,323 82871239 -3.115 .001 .001

294 5.93 3,175 18,834 31060924 3.793 1.000 0 6.48 2,907 18,834 27930148 1.893 .971 .029

295 8.34 712 5,935 2089845 -.503 .307 .307 9.01 659 5,935 1996611 .933 .825 .176

296 5.18 3,320 17,191 29430402 3.124 .999 .001 5.91 2,911 17,191 25719446 2.607 .995 .005

297 5.06 3,864 19,546 38536434 2.206 .986 .014 5.85 3,340 19,546 33200722 1.714 .957 .043

298 5.91 1,730 10,227 8955171 .886 .812 .188 6.97 1,468 10,227 7715763 1.849 .968 .032

299 10.13 23 233 2163 -1.601 .055 .055 14.56 16 233 1418 -1.658 .049 .049

300 9.01 539 4,857 1246307 -1.925 .027 .027 10.72 453 4,857 1054689 -1.522 .064 .064

301 8.34 2,023 16,871 17409101 1.571 .942 .058 10.64 1,585 16,871 13406257 .186 .574 .426

302 7.93 2,436 19,309 23732608 .779 .782 .218 10.35 1,865 19,309 18195317 .788 .785 .215

303 5.35 91 487 23245 .810 .791 .209 6.67 73 487 19043 1.055 .854 .146

304 6.06 4,131 25,051 52619054 1.885 .970 .030 7.16 3,498 25,051 44390356 1.347 .911 .089

305 7.73 201 1,554 150478 -.896 .185 .185 8.49 183 1,554 132022 -1.676 .047 .047

306 5.36 6,947 37,205 133918130 5.235 0 0 6.39 5,819 37,205 110549742 2.810 .998 .002

307 6.77 3,122 21,126 33397384 1.232 .891 .109 8.46 2,498 21,126 26897070 1.676 .953 .047

308 8.84 2,010 17,772 19454133 6.927 0 0 9.35 1,900 17,772 18012197 5.048 0 0

309 6.75 173 1,167 100184 -.172 .432 .432 7.39 158 1,167 91368 -.195 .423 .423

310 6.82 455 3,103 637066 -3.604 0 0 8.17 380 3,103 539457 -2.870 .002 .002

311 10.78 353 3,804 718452 2.280 .989 .011 12.35 308 3,804 627049 2.140 .984 .016

312 6.55 2,829 18,527 28212261 7.051 0 0 7.36 2,518 18,527 24983500 6.178 0 0

313 6.45 382 2,465 464356 -.464 .321 .321 7.59 325 2,465 387294 -1.034 .151 .151

314 7.34 154 1,131 91153 1.004 .842 .158 8.50 133 1,131 81113 1.567 .941 .059

315 4.80 3,893 18,684 36013562 -1.054 .146 .146 5.42 3,446 18,684 32524682 1.049 .853 .147

316 9.12 217 1,979 211687 -.361 .359 .359 12.61 157 1,979 149534 -.813 .208 .208

317 13.45 121 1,627 86731 -2.265 .012 .012 18.08 90 1,627 64478 -1.961 .025 .025

318 9.99 1,652 16,498 14293106 3.439 1.000 0 12.91 1,278 16,498 10987989 2.618 .996 .004

319 9.66 387 3,738 705956 -.817 .207 .207 11.94 313 3,738 582644 -.123 .451 .451

320 11.31 709 8,016 2815670 -.422 .337 .337 15.18 528 8,016 2126052 .185 .573 .427

321 5.50 3,773 20,733 39629782 1.406 .920 .080 6.46 3,208 20,733 34022889 2.263 .988 .012

322 6.84 1,833 12,538 11183917 -1.982 .024 .024 7.90 1,588 12,538 9584171 -2.572 .005 .005

323 6.53 821 5,364 2204925 .068 .527 .473 7.67 699 5,364 1874283 -.011 .496 .496

324 6.05 5,226 31,602 82908229 .504 .693 .307 7.19 4,393 31,602 70358120 1.562 .941 .059

325 9.53 447 4,259 945995 -.227 .410 .410 11.15 382 4,259 804583 -.370 .356 .356

326 5.51 1,179 6,492 3868685 .647 .741 .259 5.98 1,085 6,492 3563024 .666 .747 .253

327 8.89 914 8,126 3557929 -2.195 .014 .014 9.81 828 8,126 3283260 -1.199 .115 .115

328 9.85 99 975 43506 -1.699 .045 .045 12.34 79 975 35549 -1.185 .118 .118

329 4.78 2,421 11,566 15042131 6.340 0 0 5.41 2,138 11,566 12978722 3.982 1.000 0

330 5.04 7,242 36,526 133708538 1.614 .947 .053 5.85 6,242 36,526 114801268 .965 .833 .167

331 9.47 707 6,698 2487898 2.337 .990 .010 10.70 626 6,698 2195518 2.047 .980 .020

332 7.87 4,049 31,881 67543589 5.124 0 0 9.98 3,195 31,881 53029781 4.037 1.000 0

333 6.31 3,398 21,436 38562449 5.940 0 0 6.94 3,089 21,436 34436437 3.863 1.000 0

334 7.87 1,963 15,442 14908371 -1.255 .105 .105 9.92 1,557 15,442 11939347 -.468 .320 .320

335 8.63 2,574 22,219 29054886 1.411 .921 .079 10.20 2,179 22,219 24632741 1.420 .922 .078

336 6.43 322 2,070 366526 3.101 .999 .001 8.59 241 2,070 271691 2.399 .992 .008

Table 3. Summary of interoccurrence intervals for daily precipitation thresholds of 0.05 and 0.10 inch—Continued

Seq.

no.

Daily precipitation threshold of 0.05 inch and greater Daily precipitation threshold of 0.10 inch and greater

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue
Table 3 69

337 8.20 1,343 11,010 7821622 3.678 1.000 0 9.52 1,157 11,010 6568862 1.846 .968 .032

338 9.68 597 5,777 1732927 .208 .583 .417 10.24 564 5,777 1662481 .843 .800 .200

339 4.85 1,002 4,859 2401168 -.748 .227 .227 5.48 887 4,859 2148892 -.145 .442 .442

340 5.70 1,094 6,240 3269078 -2.420 .008 .008 7.01 890 6,240 2717310 -1.107 .134 .134

341 11.63 837 9,737 4133253 .717 .763 .237 14.28 682 9,737 3334791 .197 .578 .422

342 15.71 261 4,100 483218 -2.711 .003 .003 17.67 232 4,100 449743 -1.434 .076 .076

343 6.21 2,044 12,702 13108308 .765 .778 .222 7.45 1,705 12,702 10959430 .865 .806 .194

344 6.14 5,608 34,428 99496558 3.978 1.000 0 7.36 4,679 34,428 83353313 4.132 1.000 0

345 7.35 66 485 15754 -.221 .413 .413 8.08 60 485 14017 -.492 .312 .312

346 7.87 2,734 21,528 28552038 -2.698 .003 .003 9.88 2,180 21,528 22741716 -2.495 .006 .006

347 7.74 154 1,192 88942 -.666 .253 .253 8.83 135 1,192 74359 -1.526 .064 .064

348 7.71 1,449 11,166 7884827 -1.670 .047 .047 8.97 1,245 11,166 6789591 -1.418 .078 .078

349 9.24 1,208 11,161 6666977 -.663 .254 .254 10.33 1,080 11,161 5974216 -.498 .309 .309

350 8.49 3,321 28,183 48181272 2.951 .998 .002 9.23 3,055 28,183 44161717 2.473 .993 .007

351 8.63 448 3,865 919259 2.265 .988 .012 9.74 397 3,865 804178 1.663 .952 .048

352 26.55 40 1,062 17490 -1.934 .027 .027 26.55 40 1,062 17490 -1.934 .027 .027

353 6.80 479 3,257 794005 .678 .751 .249 7.16 455 3,257 754487 .674 .750 .250

354 5.73 1,201 6,876 4183513 .792 .786 .214 6.89 998 6,876 3507086 1.211 .887 .113

355 6.30 1,772 11,170 10093865 1.453 .927 .073 7.53 1,484 11,170 8456194 1.353 .912 .088

356 9.10 3,934 35,793 71815173 2.176 .985 .015 11.63 3,078 35,793 55372956 .502 .692 .308

357 7.18 4,398 31,587 70919601 2.414 .992 .008 8.44 3,742 31,587 60008639 1.630 .948 .052

358 7.86 2,402 18,884 23399851 2.696 .996 .004 9.53 1,981 18,884 18899407 .803 .789 .211

359 8.32 267 2,220 301823 .521 .699 .301 9.82 226 2,220 257409 .680 .752 .248

360 8.32 87 724 30375 -.574 .283 .283 12.93 56 724 18708 -1.000 .159 .159

361 7.90 19 150 1821 2.098 .982 .018 9.38 16 150 1589 2.246 .988 .012

362 6.76 3,139 21,229 36219356 8.448 0 0 7.58 2,800 21,229 30688157 2.984 .999 .001

363 5.61 390 2,188 436566 .794 .786 .214 6.45 339 2,188 376893 .518 .698 .302

364 5.56 1,724 9,588 7937535 -2.848 .002 .002 6.45 1,486 9,588 6984916 -1.303 .096 .096

365 5.64 3,954 22,280 41909221 -5.287 0 0 6.40 3,482 22,280 38063220 -1.914 .028 .028

366 8.33 303 2,525 380234 -.182 .428 .428 8.59 294 2,525 375816 .371 .645 .355

367 5.57 2,072 11,543 12095035 .900 .816 .184 6.56 1,760 11,543 10287152 .925 .822 .178

368 9.50 887 8,426 3538742 -2.736 .003 .003 11.48 734 8,426 2975146 -1.778 .038 .038

369 15.38 8 123 394 -.976 .165 .165 24.60 5 123 183 -1.568 .058 .058

370 9.71 673 6,537 2088248 -2.277 .011 .011 12.08 541 6,537 1636186 -3.009 .001 .001

371 12.02 1,640 19,719 16985834 3.541 1.000 0 16.90 1,167 19,719 12144243 3.282 .999 .001

372 8.92 914 8,156 3917278 2.669 .996 .004 10.29 793 8,156 3334811 1.523 .936 .064

373 7.15 26 186 2259 -.581 .281 .281 8.46 22 186 1821 -.893 .186 .186

374 10.41 84 874 41371 2.017 .978 .022 11.97 73 874 35500 1.670 .952 .048

375 10.62 1,010 10,721 5421803 .078 .531 .469 11.58 926 10,721 5043199 .843 .800 .200

376 9.18 317 2,910 461103 -.009 .496 .496 10.51 277 2,910 410350 .523 .700 .300

377 7.01 2,590 18,150 24169990 2.497 .994 .006 8.07 2,248 18,150 21098962 2.811 .998 .002

378 6.50 2,236 14,540 16544334 1.454 .927 .073 7.31 1,990 14,540 14619347 .812 .792 .208

379 7.24 25 181 2256 -.025 .490 .490 8.62 21 181 1845 -.232 .408 .408

380 6.32 226 1,428 179967 3.002 .999 .001 7.48 191 1,428 155136 3.293 1.000 0

381 5.85 3,250 18,998 31134458 .840 .800 .200 6.62 2,868 18,998 27546026 1.031 .849 .151

382 5.59 53 296 7865 .034 .514 .487 6.30 47 296 7059 .176 .570 .430

383 9.52 3,409 32,450 51961671 -6.124 0 0 11.58 2,803 32,450 43901647 -3.180 .001 .001

384 8.34 980 8,168 4398390 5.366 0 0 10.06 812 8,168 3545129 3.407 1.000 0

Table 3. Summary of interoccurrence intervals for daily precipitation thresholds of 0.05 and 0.10 inch—Continued

Seq.

no.

Daily precipitation threshold of 0.05 inch and greater Daily precipitation threshold of 0.10 inch and greater

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue
70 Atlas of Interoccurrence Intervals for Selected Thresholds of Daily Precipitation in Texas 

385 5.92 2,911 17,222 25934335 3.235 .999 .001 6.74 2,556 17,222 22349606 1.352 .912 .088

386 30.50 8 244 872 -.522 .301 .301 30.50 8 244 872 -.522 .301 .301

387 6.85 304 2,081 295890 -1.950 .026 .026 7.91 263 2,081 262473 -1.147 .126 .126

388 5.98 412 2,464 481568 -1.802 .036 .036 7.31 337 2,464 390689 -1.876 .030 .030

389 7.56 48 363 10048 1.840 .967 .033 9.31 39 363 8683 2.452 .993 .007

390 4.64 3,770 17,476 33801214 2.773 .997 .003 5.27 3,318 17,476 29624965 2.176 .985 .015

391 7.26 2,200 15,972 17929177 1.665 .952 .048 8.13 1,964 15,972 16173342 2.392 .992 .008

392 16.16 64 1,034 21549 -4.832 0 0 16.95 61 1,034 20938 -4.546 0 0

393 14.37 737 10,594 4142698 2.876 .998 .002 19.44 545 10,594 3084394 2.767 .997 .003

394 10.33 3 31 57 .677 .751 .249 10.33 3 31 57 .677 .751 .249

395 8.41 1,084 9,115 5128513 2.172 .985 .015 9.16 995 9,115 4671060 1.643 .950 .050

396 5.79 3,404 19,696 35121644 4.820 1.000 0 6.64 2,965 19,696 30142683 3.047 .999 .001

397 8.27 1,723 14,241 12053165 -1.263 .103 .103 10.81 1,318 14,241 9164896 -1.474 .070 .070

398 7.83 4,320 33,819 73720577 1.047 .852 .148 9.69 3,490 33,819 59062162 .083 .533 .467

399 8.42 2,329 19,618 22345905 -1.827 .034 .034 9.20 2,132 19,618 20585838 -1.250 .106 .106

400 6.24 3,091 19,271 29692201 -.295 .384 .384 6.90 2,792 19,271 26820201 -.279 .390 .390

401 8.88 651 5,779 1693507 -4.406 0 0 10.07 574 5,779 1516933 -3.544 0 0

402 17.36 14 243 2079 1.440 .925 .075 18.69 13 243 1935 1.406 .920 .080

403 9.74 1,389 13,535 9536779 .939 .826 .174 9.90 1,367 13,535 9381743 .904 .817 .183

404 6.09 3,385 20,610 35618279 2.126 .983 .017 7.03 2,932 20,610 30848521 1.969 .976 .024

405 7.98 1,490 11,884 9202875 2.638 .996 .004 9.65 1,231 11,884 7673318 2.980 .999 .001

406 6.79 3,194 21,685 35943593 3.710 1.000 0 7.41 2,927 21,685 32662902 2.737 .997 .003

407 6.11 607 3,708 1103908 -.814 .208 .208 7.00 530 3,708 967264 -.623 .267 .267

408 5.63 6,061 34,142 102954806 -.668 .252 .252 6.74 5,065 34,142 86392209 -.103 .459 .459

409 8.88 137 1,216 78220 -1.235 .108 .108 11.69 104 1,216 60234 -.838 .201 .201

410 5.52 2,610 14,398 18938720 .703 .759 .241 6.26 2,300 14,398 16629974 .363 .642 .358

411 9.33 2,051 19,141 20425136 3.181 .999 .001 10.25 1,868 19,141 18157829 1.173 .880 .120

412 6.98 1,992 13,897 12743916 -6.130 0 0 7.55 1,840 13,897 11907597 -5.100 0 0

413 8.11 3,720 30,162 58952845 5.370 0 0 9.09 3,317 30,162 51839380 3.621 1.000 0

414 8.11 422 3,423 678878 -2.137 .016 .016 8.94 383 3,423 627076 -1.470 .071 .071

415 8.57 2,507 21,490 27363506 1.371 .915 .085 10.00 2,149 21,490 23461919 1.290 .901 .099

416 8.92 2,169 19,352 21983447 3.829 1.000 0 10.54 1,837 19,352 18422659 2.706 .997 .003

417 10.38 296 3,072 467708 .856 .804 .196 10.49 293 3,072 463373 .878 .810 .190

418 7.78 3,204 24,925 40606359 1.661 .952 .048 9.15 2,724 24,925 34995356 2.789 .997 .003

419 6.20 3,654 22,658 42041703 1.633 .949 .051 7.31 3,098 22,658 35633462 1.473 .930 .070

420 10.07 1,900 19,138 19063883 3.666 1.000 0 11.63 1,645 19,138 16177156 1.947 .974 .026

421 8.59 3,630 31,191 59044277 4.484 1.000 0 10.52 2,965 31,191 46506311 .542 .706 .294

422 12.46 930 11,589 5181008 -2.038 .021 .021 15.25 760 11,589 4266480 -1.489 .068 .068

423 10.14 1,144 11,596 6981870 3.082 .999 .001 12.19 951 11,596 5745008 2.239 .987 .013

424 19.36 11 213 1637 2.283 .989 .011 21.30 10 213 1441 1.934 .973 .027

425 10.43 2,038 21,262 21829990 .592 .723 .277 13.32 1,596 21,262 17095989 .526 .700 .300

426 10.65 1,677 17,867 15581263 2.840 .998 .002 12.37 1,445 17,867 13280828 1.897 .971 .029

427 -- -- -- -- -- -- -- -- -- -- -- -- -- --

428 6.35 756 4,798 1823386 .256 .601 .399 7.85 611 4,798 1481255 .452 .674 .326

429 5.99 903 5,412 2489988 .990 .839 .161 7.19 753 5,412 2092659 1.284 .900 .100

430 6.19 1,441 8,915 6596774 1.776 .962 .038 7.40 1,205 8,915 5559217 2.104 .982 .018

431 6.10 632 3,856 1261069 1.521 .936 .064 7.28 530 3,856 1068017 1.802 .964 .036

432 4.95 1,755 8,688 7684641 .580 .719 .281 5.87 1,481 8,688 6517539 .871 .808 .192

Table 3. Summary of interoccurrence intervals for daily precipitation thresholds of 0.05 and 0.10 inch—Continued

Seq.

no.

Daily precipitation threshold of 0.05 inch and greater Daily precipitation threshold of 0.10 inch and greater

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue
Table 3 71

433 11.02 2,483 27,354 35035394 2.733 .997 .003 12.22 2,239 27,354 30829285 0.553 .710 .290

434 5.61 2,423 13,597 16796612 1.676 .953 .047 6.48 2,099 13,597 14591611 1.788 .963 .037

435 5.97 173 1,033 93934 1.168 .878 .122 6.98 148 1,033 81631 1.430 .924 .076

436 6.73 4,320 29,054 64772922 3.658 1.000 0 8.27 3,515 29,054 52488064 2.867 .998 .002

437 5.27 4,805 25,322 64203096 6.645 0 0 6.15 4,118 25,322 54317885 4.647 1.000 0

438 9.25 2,018 18,671 19520280 2.814 .998 .002 10.69 1,746 18,671 16944966 2.865 .998 .002

439 11.45 713 8,164 2809997 -1.597 .055 .055 12.58 649 8,164 2634055 -.253 .400 .400

440 8.69 1,070 9,302 4856664 -1.365 .086 .086 10.62 876 9,302 4115555 .519 .698 .302

441 8.32 2,851 23,733 35269673 3.932 1.000 0 10.49 2,263 23,733 27893982 3.191 .999 .001

442 5.67 2,252 12,769 14615282 1.357 .913 .087 6.69 1,908 12,769 12281691 .622 .733 .267

443 6.67 1,948 12,987 12919924 1.635 .949 .051 7.71 1,685 12,987 11024389 .538 .705 .295

444 8.36 193 1,613 160307 .719 .764 .236 10.02 161 1,613 137716 1.332 .909 .091

445 9.92 1,929 19,140 18080622 -1.566 .059 .059 11.52 1,662 19,140 15944196 .173 .569 .431

446 7.31 161 1,177 93220 -.355 .361 .361 8.47 139 1,177 75597 -1.549 .061 .061

447 10.51 2,183 22,938 26354449 4.259 1.000 0 11.81 1,942 22,938 23330714 3.625 1.000 0

448 6.16 5,117 31,527 81649011 1.516 .935 .065 7.21 4,371 31,527 69264648 .602 .726 .274

449 5.45 975 5,317 2453983 -2.881 .002 .002 6.48 821 5,317 2072508 -2.504 .006 .006

450 5.43 3,783 20,533 39278356 1.207 .886 .114 6.55 3,137 20,533 32792318 1.766 .961 .039

451 5.41 1,029 5,562 2853160 -.165 .435 .435 6.69 831 5,562 2308663 -.051 .480 .480

452 9.21 33 304 4696 -.635 .263 .263 12.16 25 304 3689 -.253 .400 .400

453 10.57 199 2,103 217097 .917 .820 .180 12.30 171 2,103 186433 .835 .798 .202

454 10.27 3,094 31,784 47533589 -3.206 .001 .001 11.87 2,677 31,784 41219179 -2.788 .003 .003

455 8.37 106 887 38463 -3.243 .001 .001 10.08 88 887 31080 -3.309 0 0

456 33.50 2 67 99 1.170 .879 .121 33.50 2 67 99 1.170 .879 .121

457 6.20 55 341 10632 1.718 .957 .043 7.75 44 341 8745 1.904 .972 .028

458 5.63 1,105 6,223 3241535 -3.294 0 0 6.06 1,027 6,223 3085325 -1.914 .028 .028

459 10.68 105 1,121 61435 .779 .782 .218 10.78 104 1,121 60725 .737 .769 .231

460 7.02 4,660 32,732 79989628 5.774 0 0 7.91 4,136 32,732 70496807 4.619 1.000 0

461 7.30 4,215 30,785 66579608 2.947 .998 .002 8.87 3,472 30,785 53823516 .727 .766 .234

462 6.02 2,947 17,740 27063505 3.322 1.000 0 7.31 2,426 17,740 22307132 3.126 .999 .001

463 5.49 1,363 7,477 5149739 .680 .752 .248 6.74 1,109 7,477 4234013 1.225 .890 .110

464 5.53 4,067 22,500 45975778 .536 .704 .296 6.66 3,379 22,500 38457493 1.175 .880 .120

465 7.99 246 1,966 233164 -.972 .166 .166 8.82 223 1,966 208411 -1.274 .101 .101

466 5.12 5,123 26,233 68884919 3.116 .999 .001 5.97 4,391 26,233 58958580 2.718 .997 .003

467 11.48 964 11,063 5890540 5.629 0 0 14.04 788 11,063 5014684 7.316 0 0

468 7.64 130 993 49616 -4.568 0 0 8.14 122 993 47990 -3.974 0 0

469 5.61 1,751 9,821 9026413 3.609 1.000 0 6.13 1,603 9,821 8256584 3.392 1.000 0

470 7.00 13 91 540 -.544 .293 .293 7.58 12 91 505 -.451 .326 .326

471 5.99 2,236 13,388 15126801 .870 .808 .192 7.16 1,871 13,388 12747968 1.337 .909 .091

472 6.47 521 3,372 887894 .427 .665 .335 6.85 492 3,372 842035 .580 .719 .281

473 7.55 2,548 19,226 24073941 -1.499 .067 .067 8.37 2,298 19,226 22067888 -.086 .466 .466

474 7.06 3,565 25,176 45470501 1.370 .915 .085 8.36 3,010 25,176 38465351 1.443 .926 .074

475 6.02 5,305 31,959 86022332 1.862 .969 .031 7.36 4,345 31,959 70159701 1.198 .885 .115

476 9.36 1,948 18,237 17759145 -.016 .494 .494 9.40 1,941 18,237 17699577 .003 .501 .499

477 5.78 727 4,201 1531522 .136 .554 .446 7.82 537 4,201 1137125 .326 .628 .372

478 5.97 3,864 23,063 45047131 1.183 .881 .119 7.41 3,113 23,063 36369499 1.271 .898 .102

479 6.87 261 1,792 230921 -.351 .363 .363 7.59 236 1,792 203318 -1.024 .153 .153

480 7.29 780 5,684 2125702 -1.987 .023 .023 8.67 656 5,684 1806988 -1.365 .086 .086

Table 3. Summary of interoccurrence intervals for daily precipitation thresholds of 0.05 and 0.10 inch—Continued

Seq.

no.

Daily precipitation threshold of 0.05 inch and greater Daily precipitation threshold of 0.10 inch and greater

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue
72 Atlas of Interoccurrence Intervals for Selected Thresholds of Daily Precipitation in Texas 

481 5.28 2,395 12,650 14287808 -4.815 0 0 6.03 2,097 12,650 12739801 -3.132 .001 .001

482 6.65 558 3,709 1038839 .159 .563 .437 7.71 481 3,709 871324 -.881 .189 .189

483 6.30 504 3,174 806846 .340 .633 .367 7.18 442 3,174 718477 .884 .812 .189

484 7.30 375 2,736 494289 -1.223 .111 .111 8.02 341 2,736 454807 -.801 .212 .212

485 10.73 79 848 32456 -.478 .316 .316 10.87 78 848 31987 -.502 .308 .308

486 7.24 4,805 34,779 87400256 5.523 0 0 8.27 4,207 34,779 75213655 3.157 .999 .001

487 6.43 1,631 10,484 8666470 .955 .830 .170 7.82 1,340 10,484 7035699 .103 .541 .459

488 13.29 2,117 28,138 32177361 6.404 0 0 15.85 1,775 28,138 26190483 3.559 1.000 0

489 6.00 1,939 11,627 10969306 -2.051 .020 .020 7.19 1,618 11,627 9209384 -1.458 .072 .072

490 5.82 1,341 7,802 5242592 .138 .555 .445 7.17 1,088 7,802 4260400 .217 .586 .414

491 5.89 2,168 12,770 14762067 5.356 0 0 6.37 2,004 12,770 13622912 5.014 0 0

492 6.27 3,999 25,088 52908423 5.994 0 0 7.41 3,385 25,088 44032540 3.729 1.000 0

493 5.57 6,401 35,661 117976991 4.667 1.000 0 6.43 5,549 35,661 101310569 3.089 .999 .001

494 5.31 803 4,263 1831505 3.439 1.000 0 6.45 661 4,263 1499354 2.858 .998 .002

495 5.20 3,914 20,344 42540308 7.422 0 0 5.68 3,582 20,344 38906851 7.029 0 0

496 7.99 2,698 21,557 29750654 2.074 .981 .019 9.76 2,208 21,557 24260922 1.580 .943 .057

497 8.15 100 815 41703 .405 .657 .343 12.16 67 815 29834 1.315 .906 .094

498 5.91 3,227 19,069 30788296 .065 .526 .474 6.93 2,750 19,069 26673646 1.572 .942 .058

499 8.50 2,088 17,748 19833245 5.571 0 0 9.86 1,801 17,748 16821663 3.862 1.000 0

500 7.18 161 1,156 94426 .323 .627 .373 8.50 136 1,156 78567 -.011 .496 .496

501 11.19 457 5,112 1210178 1.334 .909 .091 11.73 436 5,112 1146169 1.031 .849 .151

502 5.67 5,393 30,570 82435112 .005 .502 .498 6.36 4,805 30,570 73663606 .358 .640 .360

503 10.95 559 6,120 1692714 -.427 .335 .335 12.22 501 6,120 1508864 -.612 .270 .270

504 12.83 287 3,683 481599 -2.605 .005 .005 13.95 264 3,683 446129 -2.317 .010 .010

505 7.76 138 1,071 62103 -3.248 .001 .001 9.40 114 1,071 53040 -2.426 .008 .008

506 5.94 6,292 37,401 121673241 4.682 1.000 0 6.84 5,468 37,401 103974024 2.154 .984 .016

507 4.81 290 1,396 212376 1.451 .927 .073 5.79 241 1,396 181392 2.106 .982 .018

508 7.25 2,191 15,882 18174434 3.615 1.000 0 8.48 1,874 15,882 15221268 1.712 .957 .043

509 8.35 3,057 25,519 41526727 6.189 0 0 10.12 2,522 25,519 33373519 3.228 .999 .001

510 9.08 231 2,098 219770 -2.450 .007 .007 10.49 200 2,098 202304 -.875 .191 .191

511 5.59 3,327 18,591 29696250 -3.973 0 0 6.10 3,048 18,591 27456009 -2.959 .002 .002

512 7.14 4,418 31,532 70995558 2.217 .987 .013 8.89 3,546 31,532 55772266 -.247 .402 .402

513 8.03 2,653 21,306 30081213 5.741 0 0 9.20 2,315 21,306 25813209 3.891 1.000 0

514 6.33 6 38 123 .335 .631 .369 9.50 4 38 100 1.094 .863 .137

515 9.49 1,695 16,084 14612138 5.132 0 0 11.19 1,437 16,084 11944875 2.207 .986 .014

516 10.70 257 2,751 314392 -3.072 .001 .001 13.16 209 2,751 262679 -2.160 .015 .015

517 8.62 2,269 19,560 21798092 -1.460 .072 .072 10.42 1,878 19,560 18053331 -1.281 .100 .100

518 7.67 4,785 36,688 90590977 3.842 1.000 0 9.07 4,047 36,688 75400166 1.725 .958 .042

519 8.00 964 7,716 3725421 .091 .536 .464 9.91 779 7,716 3002316 -.049 .480 .480

520 6.91 97 670 32837 .180 .571 .429 9.05 74 670 25511 .433 .668 .332

521 6.54 2,726 17,822 24290440 -.004 .499 .499 7.15 2,494 17,822 22310965 .338 .632 .368

522 9.37 790 7,402 2908071 -.262 .397 .397 10.57 700 7,402 2536526 -.958 .169 .169

523 9.35 407 3,804 848821 3.372 1.000 0 10.20 373 3,804 764670 2.604 .995 .005

524 12.36 197 2,435 223244 -1.683 .046 .046 15.31 159 2,435 183267 -1.164 .122 .122

525 -- -- -- -- -- -- -- -- -- -- -- -- -- --

526 9.18 3,547 32,561 62440897 8.385 0 0 10.92 2,983 32,561 51015510 4.774 1.000 0

527 4.69 1,852 8,692 8171566 1.137 .872 .128 5.41 1,607 8,692 7039442 .551 .709 .291

528 4.70 672 3,157 1037024 -1.004 .158 .158 5.32 593 3,157 934966 -.049 .480 .480

Table 3. Summary of interoccurrence intervals for daily precipitation thresholds of 0.05 and 0.10 inch—Continued

Seq.

no.

Daily precipitation threshold of 0.05 inch and greater Daily precipitation threshold of 0.10 inch and greater

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue
Table 3 73

529 5.79 2,000 11,583 12025927 2.962 .998 .002 6.71 1,727 1,1583 10331470 2.372 .991 .009

530 5.22 6,542 34,124 114122703 3.142 .999 .001 6.01 5,680 34,124 99659956 3.701 1.000 0

531 10.41 611 6,363 1883719 -1.325 .093 .093 10.48 607 6,363 1876869 -1.200 .115 .115

532 6.73 5,356 36,056 100075132 4.617 1.000 0 7.96 4,531 36,056 82972372 1.838 .967 .033

533 8.53 3,018 25,757 40443197 3.858 1.000 0 10.60 2,431 25,757 31875316 1.549 .939 .061

534 7.59 130 986 58643 -1.678 .047 .047 9.57 103 986 47536 -1.123 .131 .131

535 6.50 6,459 41,954 140816640 5.472 0 0 7.63 5,496 41,954 119517359 4.709 1.000 0

536 10.07 15 151 1189 .335 .631 .369 10.07 15 151 1189 .335 .631 .369

537 6.48 4,918 31,864 82542081 6.493 0 0 7.71 4,134 31,864 67678948 3.071 .999 .001

538 10.70 214 2,290 232468 -1.299 .097 .097 12.87 178 2,290 200071 -.424 .336 .336

539 7.68 2,569 19,726 25990843 2.262 .988 .012 8.94 2,206 19,726 22380292 2.328 .990 .010

540 7.79 214 1,666 179557 .184 .573 .427 8.46 197 1,666 171808 1.142 .873 .127

541 6.05 5,790 35,035 103810184 3.098 .999 .001 7.09 4,940 35,035 88413582 2.641 .996 .004

542 8.71 136 1,184 67218 -3.335 0 0 11.72 101 1184 51183 -2.506 .006 .006

543 9.69 864 8,373 3645829 .404 .657 .343 11.13 752 8373 3130913 -.262 .397 .397

544 6.58 4,461 29,330 67663272 3.966 1.000 0 8.24 3,561 29,330 53041648 1.622 .948 .052

545 6.83 1,230 8,397 4974119 -2.235 .013 .013 8.48 990 8,397 4014609 -1.861 .031 .031

546 5.51 5,701 31,403 90540761 1.500 .933 .067 6.06 5,182 31,403 82075337 1.088 .862 .138

547 7.32 2,411 17,650 21272853 -.017 .493 .493 8.94 1,974 17,650 17518892 .434 .668 .332

548 4.74 2,766 13,112 17739848 -1.980 .024 .024 5.56 2,357 13,112 15325187 -.693 .244 .244

549 15.42 57 879 26349 .677 .751 .249 19.53 45 879 20043 .156 .562 .438

550 5.62 149 838 59591 -.962 .168 .168 7.29 115 838 45532 -1.023 .153 .153

551 5.78 950 5,486 2682809 1.577 .943 .057 6.96 788 5,486 2230157 1.545 .939 .061

552 5.39 3,631 19,567 37175303 4.852 1.000 0 6.30 3,107 19,567 31641222 3.951 1.000 0

553 3.90 39 152 2529 -1.588 .056 .056 5.07 30 152 2010 -1.123 .131 .131

554 4.66 2,552 11,901 15118744 -.386 .350 .350 5.63 2,114 11,901 12551407 -.177 .430 .430

555 4.32 34 147 1953 -2.207 .014 .014 5.25 28 147 1830 -1.015 .155 .155

556 4.61 4,337 19,994 44291741 2.459 .993 .007 5.41 3,696 19,994 38124332 3.350 1.000 0

557 7.41 37 274 5026 -.089 .464 .464 7.41 37 274 5026 -.089 .464 .464

558 8.59 248 2,129 250944 -1.349 .089 .089 8.83 241 2,129 245290 -1.180 .119 .119

559 4.75 123 584 36188 .146 .558 .442 5.78 101 584 29249 -.143 .443 .443

560 4.44 55 244 6631 -.151 .440 .440 5.08 48 244 6011 .318 .625 .375

561 4.73 3,763 17,792 33622959 .468 .680 .320 5.42 3,283 17,792 29400805 .663 .746 .254

562 4.78 4,328 20,691 45135744 .917 .820 .180 5.64 3,668 20,691 38514719 1.569 .942 .058

563 5.30 3,190 16,893 26854026 -.328 .371 .371 5.87 2,879 16,893 24302906 -.056 .478 .478

564 4.90 3,871 18,979 37963366 3.607 1.000 0 5.83 3,255 18,979 32106503 3.897 1.000 0

565 4.89 1,001 4,897 2542650 2.050 .980 .020 5.69 861 4,897 2176138 1.639 .949 .051

566 4.63 3,233 14,981 24845157 2.555 .995 .005 5.60 2,677 14,981 20428808 1.684 .954 .046

567 6.79 1,295 8,792 6385569 7.585 0 0 7.96 1,105 8,792 5420278 6.670 0 0

568 4.58 3,455 15,815 27945778 2.330 .990 .010 5.46 2,899 15,815 23415530 2.000 .977 .023

569 4.95 1,861 9,218 8476843 -.876 .191 .191 6.08 1,517 9,218 6900217 -.884 .188 .188

570 4.84 752 3,637 1336581 -1.074 .141 .141 5.48 664 3,637 1183777 -.876 .191 .191

571 4.85 3,738 18,133 34724450 2.606 .995 .005 5.86 3,097 18,133 28938052 2.949 .998 .002

572 7.36 1,736 12,769 11806536 4.708 1.000 0 8.24 1,550 12,769 10276351 2.621 .996 .004

573 10.27 491 5,041 1248230 .331 .630 .370 12.39 407 5,041 1043534 .603 .727 .273

574 4.82 2,316 11,163 13078969 .982 .837 .163 5.82 1,918 11,163 10660549 -.317 .376 .376

575 11.18 1,566 17,501 12832301 -4.357 0 0 11.81 1,482 17,501 12271536 -3.582 0 0

576 7.01 516 3,617 917177 -.675 .250 .250 8.26 438 3,617 778170 -.639 .262 .262

Table 3. Summary of interoccurrence intervals for daily precipitation thresholds of 0.05 and 0.10 inch—Continued

Seq.

no.

Daily precipitation threshold of 0.05 inch and greater Daily precipitation threshold of 0.10 inch and greater

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue
74 Atlas of Interoccurrence Intervals for Selected Thresholds of Daily Precipitation in Texas 

577 8.11 2,291 18,568 22369794 4.288 1.000 0 9.07 2,047 18,568 19740937 3.037 .999 .001

578 4.67 4,316 20,145 43673566 .525 .700 .300 5.66 3,560 20,145 36192633 .964 .832 .168

579 6.12 2,304 14,090 16553757 1.650 .950 .050 7.11 1,981 14,090 14308716 1.948 .974 .026

580 6.08 12 73 431 -.096 .462 .462 6.64 11 73 425 .336 .632 .368

581 4.15 570 2,368 668593 -.385 .350 .350 4.80 493 2368 570481 -.872 .192 .192

582 8.07 2,291 18,495 22465943 5.009 0 0 9.03 2,048 18,495 19806131 3.589 1.000 0

583 18.64 868 16,182 7226285 1.477 .930 .070 19.88 814 16,182 6873872 2.159 .985 .015

584 4.21 58 244 6886 -.354 .362 .362 4.88 50 244 6109 .018 .507 .493

585 7.27 1,807 13,130 12671531 5.018 0 0 8.57 1,533 13,130 10431632 2.476 .993 .007

586 27.47 15 412 2245 -1.834 .033 .033 34.33 12 412 1747 -1.760 .039 .039

587 7.77 470 3,651 846503 -.503 .308 .308 8.61 424 3,651 761997 -.554 .290 .290

588 7.20 1,188 8,550 4914022 -1.936 .026 .026 8.53 1,002 8,550 4118850 -2.108 .018 .018

589 5.26 1,246 6,553 4241848 2.386 .991 .009 6.42 1,021 6,553 3495247 2.481 .993 .007

590 7.71 48 370 10258 1.862 .969 .031 7.71 48 370 10258 1.862 .969 .031

591 5.52 662 3,653 1125843 -3.070 .001 .001 6.50 562 3,653 980452 -1.842 .033 .033

592 6.77 3,263 22,076 36445404 1.177 .880 .120 7.92 2,787 22,076 31000267 .706 .760 .240

593 5.45 2,849 15,514 23173951 4.494 1.000 0 6.20 2,503 15,514 20520400 4.930 1.000 0

594 4.96 1,184 5,874 3553176 1.299 .903 .097 6.01 977 5,874 2918104 .918 .821 .179

595 9.07 1,017 9,226 4729962 .454 .675 .325 9.82 940 9,226 4329183 -.086 .466 .466

596 6.12 4,202 25,710 54810738 1.650 .951 .049 7.09 3,624 25,710 47037944 1.010 .844 .156

597 4.87 4,226 20,570 45469168 5.193 0 0 5.53 3,720 20,570 39581091 3.647 1.000 0

598 5.03 208 1,047 92073 -3.858 0 0 5.75 182 1,047 79120 -3.963 0 0

599 9.71 1,822 17,699 16268078 .662 .746 .254 10.17 1,741 17,699 15763885 1.674 .953 .047

600 6.17 3,166 19,532 32996124 6.547 0 0 7.39 2,643 19,532 27051244 4.277 1.000 0

601 5.02 6,440 32,319 106588024 3.367 1.000 0 5.66 5,709 32,319 94093221 2.608 .995 .005

602 6.13 2,508 15,379 20120283 3.756 1.000 0 6.84 2,250 15,379 17862728 2.666 .996 .004

603 5.31 1,173 6,226 3729436 1.265 .897 .103 6.33 983 6,226 3107968 .850 .802 .198

604 6.24 1,967 12,277 12169249 .603 .727 .273 7.41 1,656 12,277 10243761 .544 .707 .293

605 8.10 767 6,210 2439304 1.164 .878 .122 9.57 649 6,210 2096660 1.785 .963 .037

606 10.03 525 5,266 1404962 .650 .742 .258 11.47 459 5,266 1222867 .440 .670 .330

607 9.48 411 3,895 808196 .341 .633 .367 11.03 353 3,895 694360 .326 .628 .372

608 8.12 2,605 21,162 29312477 5.609 0 0 9.71 2,180 21,162 24009611 3.306 1.000 0

609 14.26 203 2,895 262526 -2.630 .004 .004 17.23 168 2,895 216010 -2.508 .006 .006

610 8.35 3,653 30,487 54999369 -1.288 .099 .099 9.50 3,210 30,487 47559552 -2.752 .003 .003

611 7.86 1,046 8,219 4478117 2.340 .990 .010 10.10 814 8,219 3440202 1.404 .920 .080

612 9.12 396 3,610 684079 -1.480 .069 .069 11.01 328 3,610 581711 -.547 .292 .292

613 10.44 66 689 21817 -.569 .285 .285 11.48 60 689 19635 -.672 .251 .251

614 9.69 346 3,354 578314 -.107 .457 .457 11.73 286 3,354 471356 -.505 .307 .307

615 7.63 8 61 236 -.161 .436 .436 8.71 7 61 223 .204 .581 .419

616 9.94 189 1,878 165890 -1.554 .060 .060 11.11 169 1,878 149166 -1.352 .088 .088

617 6.69 262 1,753 201961 -3.380 0 0 6.93 253 1,753 194012 -3.447 0 0

618 4.99 4,133 20,642 42947125 .758 .776 .224 5.77 3,575 20,642 37338693 1.238 .892 .108

619 7.29 3,903 28,443 55973136 .910 .818 .182 8.34 3,412 28,443 47988867 -1.115 .132 .132

620 6.51 107 697 37658 .177 .570 .430 7.74 90 697 31765 .210 .583 .417

621 5.33 3,095 16,498 26117002 2.213 .987 .013 6.28 2,628 16,498 22409196 2.993 .999 .001

622 5.84 6,194 36,185 110456864 -1.956 .025 .025 6.74 5,371 36,185 95539437 -2.136 .016 .016

623 6.81 1,081 7,364 4057369 1.104 .865 .135 8.00 921 7,364 3437883 .725 .766 .234

624 7.34 265 1,944 252111 -.599 .275 .275 7.87 247 1,944 228750 -1.285 .099 .099

Table 3. Summary of interoccurrence intervals for daily precipitation thresholds of 0.05 and 0.10 inch—Continued

Seq.

no.

Daily precipitation threshold of 0.05 inch and greater Daily precipitation threshold of 0.10 inch and greater

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue
Table 3 75

625 6.60 1,510 9,960 7884995 3.269 .999 .001 8.26 1,206 9,960 6246594 2.411 .992 .008

626 7.24 1,495 10,827 8073364 -.164 .435 .435 8.13 1,332 10,827 7185174 -.225 .411 .411

627 10.53 1,123 11,821 6851917 1.875 .970 .030 12.54 943 11,821 5940725 3.503 1.000 0

628 8.60 582 5,003 1370446 -2.452 .007 .007 10.78 464 5,003 1091438 -2.226 .013 .013

629 5.87 4,507 26,452 61517362 3.722 1.000 0 7.51 3,523 26,452 47339847 1.643 .950 .050

630 5.94 1,670 9,923 8172530 -.967 .167 .167 7.50 1,323 9,923 6480972 -.798 .213 .213

631 6.79 1,604 10,894 8969681 1.848 .968 .032 7.88 1,382 10,894 7732516 1.752 .960 .040

632 5.77 1,380 7,960 5551979 .698 .757 .243 6.89 1,155 7,960 4640067 .553 .710 .290

633 6.38 267 1,702 209905 -2.156 .016 .016 7.06 241 1702 197091 -1.049 .147 .147

634 11.15 26 290 3556 -.501 .308 .308 11.60 25 290 3326 -.714 .238 .238

635 8.69 3,089 26,842 45266631 8.845 0 0 10.23 2,625 26,842 37534052 5.803 0 0

636 4.45 4,660 20,742 46871130 -3.566 0 0 5.17 4,015 20,742 40533774 -2.915 .002 .002

637 10.33 2,363 24,410 29136034 .863 .806 .194 11.91 2,049 24,410 25565614 1.748 .960 .040

638 8.07 1,377 11,115 7841056 1.582 .943 .057 9.52 1,167 11,115 6645593 1.460 .928 .072

639 6.36 821 5,224 2233257 2.055 .980 .020 7.39 707 5,224 1884622 .946 .828 .172

640 4.35 1,348 5,865 4107494 2.485 .994 .006 4.97 1,181 5,865 3627940 2.830 .998 .002

641 7.04 170 1,196 101108 -.123 .451 .451 8.79 136 1,196 78441 -.717 .237 .237

642 5.96 49 292 8161 1.707 .956 .044 7.68 38 292 5936 .747 .772 .228

643 5.57 5,894 32,853 96258687 -.768 .221 .221 6.66 4,933 32,853 82382726 2.028 .979 .021

644 10.35 239 2,473 311846 1.479 .930 .070 13.37 185 2,473 242329 1.398 .919 .081

645 8.84 3,103 27,442 41784993 -1.793 .036 .036 11.04 2,485 27,442 34045296 -.130 .448 .448

646 13.59 1,524 20,715 15447951 -1.443 .075 .075 17.94 1,155 20,715 11964485 .008 .503 .497

647 7.32 124 907 62628 2.193 .986 .014 8.48 107 907 54683 2.274 .989 .011

648 12.34 155 1,913 124845 -3.405 0 0 12.34 155 1,913 124845 -3.405 0 0

649 12.59 649 8,170 2509365 -2.360 .009 .009 15.99 511 8,170 1923587 -3.073 .001 .001

650 7.56 1,903 14,391 13923930 1.274 .899 .101 8.97 1,605 14,391 11604868 .337 .632 .368

651 8.73 321 2,802 452378 .183 .573 .427 11.08 253 2,802 349962 -.349 .364 .364

652 6.94 115 798 47791 .772 .780 .220 9.07 88 798 36852 .805 .790 .210

653 6.15 176 1,083 99418 .992 .839 .161 7.27 149 1,083 84491 .998 .841 .159

654 9.13 1,134 10,351 6092101 2.217 .987 .013 10.88 951 10,351 5099434 1.927 .973 .027

655 7.69 372 2,861 498435 -2.116 .017 .017 8.80 325 2,861 444301 -1.384 .083 .083

656 4.95 959 4,743 2247306 -.636 .262 .262 6.01 789 4,743 1862818 -.216 .415 .415

657 7.50 1,547 11,595 9036042 .511 .695 .305 8.76 1,324 11,595 7720889 .370 .644 .356

658 7.88 727 5,729 2138127 1.248 .894 .106 9.30 616 5,729 1809837 1.104 .865 .135

659 6.59 421 2,776 581895 -.149 .441 .441 7.80 356 2,776 484084 -.664 .253 .253

660 5.20 924 4,805 2250051 .715 .763 .237 6.04 795 4,805 1938316 .724 .765 .235

661 5.13 552 2,832 791513 .514 .696 .304 6.25 453 2,832 643472 .116 .546 .454

662 9.62 571 5,490 1626886 1.571 .942 .058 10.06 546 5,490 1549071 1.358 .913 .087

663 9.55 3,417 32,622 56317146 1.058 .855 .145 11.45 2,850 32,622 46231575 -.507 .306 .306

664 6.40 5,794 37,084 109984292 3.132 .999 .001 7.76 4,779 37,084 90422418 2.446 .993 .007

665 11.86 1,587 18,826 15190727 1.165 .878 .122 14.54 1,295 18,826 12114610 -.385 .350 .350

666 12.03 108 1,299 77533 1.896 .971 .029 15.46 84 1,299 58488 1.144 .874 .126

667 9.08 1,507 13,689 10217158 -.636 .263 .263 11.51 1,189 13,689 7983827 -1.132 .129 .129

668 10.12 767 7,761 3102169 2.028 .979 .021 13.71 566 7,761 2281365 1.595 .945 .055

669 5.07 1,120 5,676 3173774 -.087 .465 .465 5.93 957 5,676 2704616 -.224 .411 .411

670 7.60 1,116 8,485 4668136 -.813 .208 .208 9.16 926 8,485 3836478 -1.235 .108 .108

671 5.47 3,435 18,797 33302341 3.203 .999 .001 6.52 2,882 18,797 27961386 3.003 .999 .001

672 8.88 2,178 19,344 21412987 1.333 .909 .091 10.04 1,927 19,344 18852798 .877 .810 .190

Table 3. Summary of interoccurrence intervals for daily precipitation thresholds of 0.05 and 0.10 inch—Continued

Seq.

no.

Daily precipitation threshold of 0.05 inch and greater Daily precipitation threshold of 0.10 inch and greater

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue
76 Atlas of Interoccurrence Intervals for Selected Thresholds of Daily Precipitation in Texas 

673 10.56 519 5,481 1425639 0.092 .537 .463 11.01 498 5,481 1383702 0.536 .704 .296

674 11.04 162 1,788 145512 .104 .542 .459 11.18 160 1,788 142917 -.019 .492 .492

675 6.86 386 2,649 513624 .158 .563 .437 8.92 297 2,649 394801 .108 .543 .457

676 8.77 379 3,324 586696 -2.313 .010 .010 9.18 362 3,324 556960 -2.448 .007 .007

677 10.37 1,982 20,545 21033954 2.552 .995 .005 12.19 1,685 20,545 17518651 .861 .805 .195

678 9.24 17 157 1566 1.239 .892 .108 9.24 17 157 1566 1.239 .892 .108

679 8.20 2,759 22,630 31902151 1.994 .977 .023 10.23 2,212 22,630 25090678 .202 .580 .420

680 8.00 545 4,360 1265897 2.648 .996 .004 8.70 501 4,360 1124556 1.149 .875 .125

681 7.48 112 838 44917 -.786 .216 .216 7.98 105 838 42359 -.660 .255 .255

682 6.79 750 5,092 1897222 -.305 .380 .380 8.13 626 5,092 1618083 .660 .745 .255

683 5.92 2,061 12,199 12627838 .355 .639 .361 6.91 1,765 12,199 10788558 .155 .562 .438

684 5.98 2,598 15,522 20214328 .224 .589 .411 7.19 2,160 15,522 17045965 1.355 .912 .088

685 4.56 7,723 35,218 141791766 6.489 0 0 5.26 6,692 35,218 121193839 4.033 1.000 0

686 7.93 737 5,847 2147473 -.156 .438 .438 8.47 690 5,847 2015429 -.040 .484 .484

687 11.06 140 1,548 104990 -.637 .262 .262 11.64 133 1,548 101399 -.299 .382 .382

688 9.43 476 4,487 1092225 .861 .805 .195 9.45 475 4,487 1089633 .849 .802 .198

689 6.96 848 5,899 2436681 -1.301 .097 .097 7.46 791 5,899 2292282 -.851 .197 .197

690 4.97 2,520 12,527 15476876 -1.692 .045 .045 5.88 2,131 12,527 13071916 -1.651 .049 .049

691 5.24 3,493 18,319 32372061 1.209 .887 .113 5.88 3,118 18,319 29059299 1.693 .955 .045

692 7.60 2,473 18,792 21205039 -7.530 0 0 8.88 2,116 18,792 18518171 -5.465 0 0

693 7.62 2,516 19,163 24761379 2.358 .991 .009 9.18 2,087 19,163 20698114 2.776 .997 .003

694 7.29 1,001 7,301 3717190 .945 .828 .172 7.98 915 7,301 3358148 .281 .611 .389

695 9.46 1,430 13,531 9499593 -1.185 .118 .118 11.35 1,192 13,531 7897529 -1.238 .108 .108

696 8.14 1,575 12,822 9920130 -1.206 .114 .114 10.23 1,254 12,822 7946824 -.706 .240 .240

697 4.68 5,042 23,585 59208287 -.516 .303 .303 5.49 4,298 23,585 51073270 .872 .808 .192

698 7.24 5,183 37,526 101467418 5.410 0 0 8.77 4,279 37,526 83436632 4.445 1.000 0

699 6.26 253 1,583 213455 1.817 .965 .035 7.72 205 1,583 172203 1.520 .936 .064

700 6.06 3,244 19,662 33650754 5.441 0 0 7.51 2,620 19,662 27041782 4.422 1.000 0

701 7.63 235 1,793 212993 .292 .615 .385 8.08 222 1,793 199589 .073 .529 .471

702 8.91 136 1,212 72548 -2.419 .008 .008 11.02 110 1,212 56686 -2.718 .003 .003

703 9.98 473 4,722 1161089 1.496 .933 .067 10.27 460 4,722 1114868 .985 .838 .162

704 9.64 44 424 9296 -.039 .484 .484 11.46 37 424 7425 -.563 .287 .287

705 5.99 2,145 12,843 14150307 2.191 .986 .014 6.59 1,949 12,843 12989894 2.898 .998 .002

706 5.03 7,137 35,879 130770518 3.127 .999 .001 5.74 6,250 35,879 113894304 2.165 .985 .015

707 4.77 1,951 9,308 9223112 1.206 .886 .114 5.58 1,668 9308 7965217 1.844 .967 .033

708 11.53 1,402 16,163 11763375 2.479 .993 .007 13.04 1,240 16,163 10379867 2.184 .986 .014

709 7.38 8 59 273 .768 .779 .221 7.38 8 59 273 .768 .779 .221

710 7.88 152 1,198 88077 -.697 .243 .243 9.43 127 1,198 72096 -1.020 .154 .154

711 11.45 1,294 14,820 9629743 .268 .606 .394 12.19 1,216 14,820 9118694 .725 .766 .234

712 11.56 116 1,341 80076 .551 .709 .291 13.28 101 1,341 68907 .305 .620 .380

713 5.38 1,889 10,153 9420026 -1.331 .092 .092 5.97 1,702 10,153 8702879 .518 .698 .302

714 9.13 40 365 5778 -2.284 .011 .011 12.59 29 365 3480 -3.194 .001 .001

715 9.61 152 1,460 110321 -.123 .451 .451 11.68 125 1,460 90913 -.072 .471 .471

716 9.40 672 6,316 2156964 .736 .769 .231 11.61 544 6,316 1784470 1.564 .941 .059

717 8.24 4,025 33,144 67320307 1.018 .846 .154 10.38 3,194 33,144 52787571 -.265 .395 .395

718 4.72 1,458 6,885 5000041 -.252 .400 .400 5.51 1,250 6,885 4305727 .037 .515 .485

719 4.89 892 4,364 1871226 -1.997 .023 .023 5.52 790 4,364 1652127 -2.024 .022 .022

720 4.93 6,743 33,230 114956102 3.708 1.000 0 5.81 5,720 33,230 96890105 2.553 .995 .005

Table 3. Summary of interoccurrence intervals for daily precipitation thresholds of 0.05 and 0.10 inch—Continued

Seq.

no.

Daily precipitation threshold of 0.05 inch and greater Daily precipitation threshold of 0.10 inch and greater

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue
Table 3 77

721 5.59 6,527 36,455 118286971 -0.804 .211 .211 6.98 5,223 36,455 95013161 -0.249 .402 .402

722 6.70 241 1,614 200493 .830 .797 .203 7.84 206 1,614 174339 1.211 .887 .113

723 4.27 528 2,252 595103 .039 .515 .485 4.97 453 2,252 510231 .011 .504 .496

724 8.05 1,137 9,151 5438884 2.656 .996 .004 8.99 1,018 9,151 4830018 2.043 .979 .021

725 6.87 1,334 9,162 6068627 -.439 .330 .330 8.54 1,073 9,162 4911956 -.040 .484 .484

726 6.13 190 1,165 115012 .936 .825 .175 7.19 162 1,165 97900 .826 .795 .205

727 5.45 4,636 25,281 59652251 2.115 .983 .017 6.24 4,050 25,281 52062450 1.870 .969 .031

728 5.34 1,929 10,305 10488813 4.207 1.000 0 6.04 1,707 10,305 9302696 4.128 1.000 0

729 7.25 890 6,453 2883602 .216 .586 .414 8.28 779 6,453 2537688 .466 .679 .321

730 6.50 2 13 9 -.754 .226 .226 6.50 2 13 9 -.754 .226 .226

731 8.40 744 6,252 2315484 -.208 .417 .417 8.40 744 6,252 2315484 -.208 .417 .417

732 6.75 1,010 6,819 3334745 -1.740 .041 .041 8.39 813 6,819 2699492 -1.291 .098 .098

733 14.96 23 344 4693 1.548 .939 .061 17.20 20 344 3943 1.133 .871 .129

734 10.09 2,286 23,057 25752201 -1.892 .029 .029 12.73 1,812 23,057 20112729 -2.742 .003 .003

735 7.04 281 1,979 259653 -1.921 .027 .027 8.96 221 1,979 202014 -1.962 .025 .025

736 8.79 921 8,096 3824605 1.359 .913 .087 9.78 828 80,96 3441357 1.333 .909 .091

737 13.04 203 2,647 284710 1.473 .930 .070 15.48 171 2,647 239442 1.313 .905 .095

738 8.35 1,716 14,333 12346452 .284 .612 .388 11.12 1,289 14,333 9249558 .080 .532 .468

739 11.65 428 4,987 1137833 2.371 .991 .009 13.55 368 4,987 925176 .274 .608 .392

740 8.72 111 968 52427 -.441 .330 .330 10.52 92 968 44677 .056 .522 .478

741 8.88 16 142 953 -1.116 .132 .132 9.47 15 142 861 -1.285 .099 .099

742 5.58 4,747 26,466 63172979 .676 .750 .250 6.77 3,908 26,466 51883438 .354 .638 .362

743 4.93 6,780 33,395 115464929 2.842 .998 .002 5.68 5,875 33,395 99505179 1.905 .972 .028

744 8.04 788 6,333 2581519 1.682 .954 .046 9.61 659 6,333 2120816 .726 .766 .234

745 6.64 1,348 8,954 6020973 -.148 .441 .441 7.90 1,133 8,954 5102879 .350 .637 .363

746 7.49 2,745 20,552 29723174 4.876 1.000 0 8.89 2,311 20,552 24911878 4.081 1.000 0

747 7.84 2,496 19,569 25028954 2.150 .984 .016 9.44 2,072 19,569 20739583 1.813 .965 .035

748 6.24 5,278 32,946 92812855 8.493 0 0 7.34 4,490 32,946 78353778 6.889 0 0

749 6.13 2,215 13,573 14320146 -3.861 0 0 7.73 1,756 13,573 11390849 -3.205 .001 .001

750 5.37 3,459 18,579 31420978 -2.255 .012 .012 5.89 3,152 18,579 28719037 -1.865 .031 .031

751 5.85 1,303 7,628 4692204 -3.490 0 0 7.04 1,083 7,628 4001391 -1.783 .037 .037

752 12.94 94 1,216 55075 -.610 .271 .271 15.79 77 1,216 44014 -.910 .182 .182

753 7.13 285 2,033 281016 -.877 .190 .190 8.04 253 2,033 258296 .120 .548 .452

754 4.72 546 2,575 664383 -2.222 .013 .013 5.56 463 2,575 551420 -2.794 .003 .003

755 7.64 2,815 21,499 29672321 -1.784 .037 .037 10.15 2,119 21,499 22565483 -.745 .228 .228

756 32.00 2 64 37 -1.033 .151 .151 32.00 2 64 37 -1.033 .151 .151

757 11.57 505 5,844 1565470 2.370 .991 .009 12.23 478 5,844 1464973 1.851 .968 .032

758 6.08 5,322 32,344 88482876 3.546 1.000 0 6.95 4,655 32,344 76515823 1.939 .974 .026

759 7.16 2,149 15,392 16298873 -1.164 .122 .122 8.39 1,834 15,392 14156566 .221 .588 .412

760 8.46 2,522 21,345 27037603 .393 .653 .347 10.67 2,000 21,345 21566558 .804 .789 .211

761 8.28 1,634 13,531 11015307 -.250 .401 .401 10.50 1,289 13,531 8696495 -.173 .431 .431

762 10.99 2,301 25,291 29134628 .107 .542 .458 14.19 1,783 25,291 22577064 .098 .539 .461

763 10.48 113 1,184 56510 -2.859 .002 .002 10.48 113 1,184 56510 -2.859 .002 .002

764 6.51 5,040 32,783 87030134 6.574 0 0 7.53 4,353 32,783 73765429 3.865 1.000 0

765 6.06 2,013 12,195 12071544 -1.284 .100 .100 7.32 1,666 12,195 10137454 -.146 .442 .442

766 6.48 413 2,674 490020 -3.963 0 0 7.58 353 2,674 419549 -3.614 0 0

767 8.96 3,705 33,202 61889219 .656 .744 .256 9.92 3,348 33,202 55362015 -.393 .347 .347

768 8.33 4,073 33,925 73247300 6.654 0 0 9.98 3,398 33,925 59680213 3.576 1.000 0

Table 3. Summary of interoccurrence intervals for daily precipitation thresholds of 0.05 and 0.10 inch—Continued

Seq.

no.

Daily precipitation threshold of 0.05 inch and greater Daily precipitation threshold of 0.10 inch and greater

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue
78 Atlas of Interoccurrence Intervals for Selected Thresholds of Daily Precipitation in Texas 

769 10.28 206 2,118 201720 -1.873 .031 .031 11.90 178 2,118 172915 -1.911 .028 .028

770 15.47 526 8,136 2190574 .943 .827 .173 19.61 415 8,136 1775401 1.822 .966 .034

771 10.12 367 3,714 717410 1.747 .960 .040 11.12 334 3,714 651889 1.615 .947 .053

772 12.20 15 183 1179 -.946 .172 .172 13.07 14 183 1156 -.632 .264 .264

773 8.76 59 517 13041 -1.928 .027 .027 11.49 45 517 10063 -1.568 .058 .058

774 7.80 3,956 30,870 60735151 -.581 .281 .281 9.64 3,204 30,870 49011551 -.877 .190 .190

775 11.69 26 304 4026 .165 .566 .434 12.16 25 304 3871 .162 .564 .436

776 7.12 986 7,015 3449908 -.134 .447 .447 7.73 907 7,015 3188652 .121 .548 .452

777 8.59 798 6,852 2433653 -5.374 0 0 9.10 753 6,852 2331951 -4.566 0 0

778 9.09 1,072 9,749 5093470 -1.433 .076 .076 10.22 954 9,749 4395628 -2.930 .002 .002

779 9.36 1,710 16,007 13585757 -.525 .300 .300 10.97 1,459 16,007 11904492 1.288 .901 .099

780 5.49 6,296 34,558 109646660 1.084 .861 .139 6.61 5,230 34,558 91771734 1.944 .974 .026

781 7.24 4,784 34,614 82457373 -.491 .312 .312 8.73 3,966 34,614 68052835 -.932 .176 .176

782 6.05 1,537 9,303 7282368 1.263 .897 .103 6.32 1,472 9,303 7029255 1.769 .962 .038

783 11.32 129 1,460 73427 -4.333 0 0 12.17 120 1,460 70598 -3.683 0 0

784 12.36 382 4,721 764479 -5.152 0 0 14.26 331 4,721 689993 -3.684 0 0

785 12.55 1,520 19,079 14243479 -1.195 .116 .116 14.65 1,302 19,079 12198598 -1.116 .132 .132

786 10.50 1,861 19,541 18359848 .727 .766 .234 13.62 1,435 19,541 14168265 .691 .755 .245

787 9.22 657 6,055 1973464 -.348 .364 .364 9.24 655 6,055 1973129 -.221 .413 .413

788 6.06 266 1,612 226559 1.603 .945 .055 7.23 223 1,612 189817 1.450 .927 .074

789 5.18 1,611 8,344 6794754 .762 .777 .223 5.79 1,441 8,344 6066389 .597 .725 .275

790 6.59 337 2,219 349650 -2.062 .020 .020 6.85 324 2,219 337847 -1.876 .030 .030

791 10.62 444 4,714 1048353 .064 .526 .474 11.20 421 4,714 997287 .179 .571 .429

792 6.43 70 450 18101 2.163 .985 .015 7.63 59 450 15630 2.360 .991 .009

793 6.55 2,927 19,181 28996789 3.089 .999 .001 7.06 2,716 19,181 26751416 2.438 .993 .007

794 4.97 2,349 11,685 13742433 .113 .545 .455 5.82 2,007 11,685 11626908 -.655 .256 .256

795 6.41 2,661 17,047 23167884 1.918 .972 .028 7.65 2,229 17,047 19480315 2.072 .981 .019

796 10.73 487 5,225 1364523 2.771 .997 .003 13.16 397 5,225 1143298 3.532 1.000 0

797 8.47 3,362 28,459 48796044 2.008 .978 .022 10.60 2,685 28,459 39063772 2.015 .978 .022

798 9.91 70 694 21673 -1.561 .059 .059 14.46 48 694 14852 -1.300 .097 .097

799 8.82 1,038 9,155 4384384 -4.311 0 0 9.14 1,002 9,155 4316190 -3.233 .001 .001

800 7.97 144 1,148 82022 -.159 .437 .437 9.81 117 1,148 65697 -.408 .342 .342

801 11.60 1,276 14,804 9452073 .047 .519 .481 15.14 978 1,4804 7302270 .472 .682 .318

802 15.59 97 1,512 64159 -2.134 .016 .016 19.90 76 1512 47792 -2.540 .006 .006

803 6.69 1,091 7,299 4021909 .579 .719 .281 7.93 920 7,299 3336394 -.331 .370 .370

804 8.51 80 681 27084 -.089 .465 .465 10.81 63 681 21756 .195 .577 .423

805 7.29 1,576 11,493 9106657 .381 .648 .352 8.95 1,284 11,493 7376182 -.020 .492 .492

806 4.87 3,525 17,161 30388007 .482 .685 .315 5.77 2,974 17,161 26024909 1.875 .970 .030

807 6.27 2,094 13,131 13634389 -.656 .256 .256 7.12 1,845 13,131 12054753 -.360 .359 .359

808 7.98 2,258 18,012 22152347 7.353 0 0 8.67 2,078 18,012 20043962 5.609 0 0

809 9.59 1,924 18,442 19075667 5.715 0 0 11.10 1,662 18,442 15914540 2.715 .997 .003

810 8.99 2,289 20,566 24720058 4.162 1.000 0 10.97 1,874 20,566 20200876 3.621 1.000 0

811 5.35 1,379 7,376 4982517 -1.306 .096 .096 6.01 1,228 7,376 4405946 -1.647 .050 .050

812 10.04 666 6,684 2303311 1.557 .940 .060 10.59 631 6,684 2184190 1.555 .940 .060

813 4.88 17 83 657 -.491 .312 .312 5.93 14 83 506 -.837 .201 .201

814 6.72 3,634 24,404 44243812 -.231 .408 .408 8.78 2,780 24,404 34049986 .346 .635 .365

815 5.38 5,645 30,377 86442940 1.068 .857 .143 6.03 5,034 30,377 76150935 -.495 .310 .310

816 4.88 2,648 12,922 16893238 -1.123 .131 .131 5.76 2,244 12,922 14305890 -1.090 .138 .138

Table 3. Summary of interoccurrence intervals for daily precipitation thresholds of 0.05 and 0.10 inch—Continued

Seq.

no.

Daily precipitation threshold of 0.05 inch and greater Daily precipitation threshold of 0.10 inch and greater

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue
Table 3 79

817 7.62 816 6,220 2550892 0.256 .601 .399 7.74 804 6,220 2497915 -0.050 .480 .480

818 5.80 3,421 19,833 34600881 2.020 .978 .022 6.94 2,857 19,833 29076799 2.436 .993 .007

819 8.37 3,447 28,862 50068754 .665 .747 .253 10.44 2,764 28,862 40521059 1.447 .926 .074

820 7.07 126 891 50480 -1.958 .025 .025 9.58 93 891 35308 -2.469 .007 .007

821 8.76 909 7,961 3452785 -2.388 .008 .008 11.03 722 7,961 2756693 -1.898 .029 .029

822 7.49 2,544 19,050 25287550 3.807 1.000 0 8.51 2,238 19,050 22222932 3.483 1.000 0

823 7.41 4,394 32,540 72234060 1.194 .884 .116 8.96 3,631 32,540 59877723 1.416 .922 .078

824 7.58 280 2,122 287627 -.922 .178 .178 8.73 243 2,122 247701 -1.060 .145 .145

825 18.22 222 4,045 455906 .397 .654 .346 18.22 222 4,045 455906 .397 .654 .346

826 4.87 5,439 26,503 73083059 1.787 .963 .037 5.68 4,667 26,503 62261988 .798 .788 .212

827 4.81 2,170 10,437 11539885 1.537 .938 .062 5.59 1,866 10,437 9784280 .358 .640 .360

828 5.88 4,394 25,827 60568979 7.744 0 0 6.34 4,077 25,827 55146765 5.248 0 0

829 5.13 1,052 5,401 2716936 -2.452 .007 .007 5.61 962 5,401 2515989 -1.693 .045 .045

830 7.30 1,794 13,102 12356078 3.768 1.000 0 8.75 1,497 13,102 10162056 2.427 .992 .008

831 5.64 2,514 14,176 18035850 1.056 .854 .146 6.83 2,077 14,176 15092351 1.987 .977 .023

832 6.71 261 1,752 210037 -2.276 .011 .011 7.62 230 1,752 187945 -1.765 .039 .039

833 8.42 195 1,641 145926 -2.127 .017 .017 10.26 160 1,641 117937 -2.227 .013 .013

834 8.89 462 4,106 954054 .219 .587 .413 10.21 402 4,106 857554 1.357 .913 .087

835 5.69 3,261 18,549 29572684 -2.196 .014 .014 6.22 2,980 18,549 26993481 -2.205 .014 .014

836 7.02 1,075 7,548 4190875 1.873 .969 .031 8.28 912 7,548 3575917 2.037 .979 .021

837 5.01 2,384 11,942 14589198 2.105 .982 .018 5.57 2,144 11,942 13014802 1.334 .909 .091

838 5.23 1,457 7,618 5368788 -2.155 .016 .016 5.92 1,286 7,618 4741672 -1.987 .023 .023

839 4.71 478 2,252 528928 -.654 .257 .257 5.52 408 2,252 458317 -.083 .467 .467

840 6.42 5,675 36,458 105611504 2.727 .997 .003 7.57 4,814 36,458 88968654 1.663 .952 .048

841 4.93 3,664 18,077 33047258 -.221 .413 .413 5.74 3,147 18,077 28619530 .599 .725 .275

842 5.09 3,680 18,731 34134364 -1.008 .157 .157 6.23 3,006 18,731 28009556 -.483 .315 .315

843 6.04 595 3,594 1004681 -2.550 .005 .005 6.57 547 3,594 932080 -2.097 .018 .018

844 7.79 2,255 17,555 20597164 3.341 1.000 0 8.36 2,101 17,555 19051914 2.628 .996 .004

845 4.69 797 3,740 1465730 -.809 .209 .209 5.22 716 3,740 1349276 .359 .640 .360

846 4.78 1,355 6,477 4213352 -2.540 .006 .006 5.41 1,197 6,477 3728098 -2.294 .011 .011

847 8.12 2,210 17,934 21774066 8.041 0 0 8.95 2,004 17,934 19452778 6.399 0 0

848 6.11 4,711 28,763 67953258 .355 .639 .361 7.60 3,787 28,763 54963067 .979 .836 .164

849 5.20 1,304 6,785 4506677 1.172 .879 .121 6.11 1,111 6,785 3844199 1.151 .875 .125

850 10.76 133 1,431 89369 -1.216 .112 .112 10.76 133 1,431 89369 -1.216 .112 .112

851 5.70 64 365 14197 2.986 .999 .001 6.64 55 365 12335 2.940 .998 .002

852 5.79 79 457 18638 .500 .692 .309 6.18 74 457 17341 .381 .648 .352

853 4.64 59 274 8197 .188 .574 .426 5.96 46 274 6285 -.032 .487 .487

854 8.52 2,219 18,899 20923548 -.175 .431 .431 10.06 1,878 18,899 17894692 .628 .735 .265

855 5.91 943 5,570 2575394 -1.030 .152 .152 7.15 779 5,570 2152990 -.368 .356 .356

856 7.79 2,403 18,709 22519849 .155 .562 .438 9.52 1,965 18,709 18643308 1.093 .863 .137

857 8.43 1,079 9,100 5144663 2.726 .997 .003 9.51 957 9,100 4618130 3.246 .999 .001

858 8.18 1,294 10,580 6952267 .974 .835 .165 9.40 1,125 10,580 6058352 1.046 .852 .148

859 7.78 1,204 9,367 5721319 .878 .810 .190 9.79 957 9,367 4498028 .190 .576 .424

860 9.43 129 1,217 73773 -1.184 .118 .118 11.70 104 1,217 56098 -2.006 .022 .022

861 8.07 1,791 14,445 12788652 -.832 .203 .203 9.61 1,503 14,445 10797210 -.360 .359 .359

862 6.04 1,264 7,632 4857089 .430 .666 .334 6.27 1,217 7,632 4670595 .345 .635 .365

863 5.68 75 426 16343 .346 .635 .365 6.27 68 426 14841 .352 .638 .362

864 11.97 1,510 18,069 13858888 1.070 .858 .142 14.68 1231 18,069 11260140 .758 .776 .224

Table 3. Summary of interoccurrence intervals for daily precipitation thresholds of 0.05 and 0.10 inch—Continued

Seq.

no.

Daily precipitation threshold of 0.05 inch and greater Daily precipitation threshold of 0.10 inch and greater

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue
80 Atlas of Interoccurrence Intervals for Selected Thresholds of Daily Precipitation in Texas 

865 9.29 252 2,342 282011 -1.219 .112 .112 11.31 207 2,342 230874 -1.185 .118 .118

866 10.97 248 2,721 370217 2.653 .996 .004 12.84 212 2,721 301859 1.175 .880 .120

867 6.95 2,289 15,899 18409627 .971 .834 .166 8.29 1,918 15,899 15544083 1.477 .930 .070

868 8.25 2,636 21,746 28674364 .041 .516 .484 9.00 2,416 21,746 26378012 .353 .638 .362

869 8.67 2,127 18,440 20017944 1.658 .951 .049 10.59 1,741 18,440 16210441 .713 .762 .238

870 5.03 313 1,575 264309 2.216 .987 .013 5.69 277 1,575 232460 1.893 .971 .029

871 14.82 17 252 2651 1.697 .955 .045 14.82 17 252 2651 1.697 .955 .045

872 9.35 52 486 12227 -.404 .343 .343 9.92 49 486 11426 -.490 .312 .312

873 4.41 5,324 23,470 62751849 .556 .711 .289 5.21 4,503 23,470 53397884 1.221 .889 .111

874 4.00 1,430 5,724 3975056 -1.882 .030 .030 4.79 1,195 5,724 3342607 -1.357 .088 .088

875 4.18 116 485 26025 -1.396 .081 .081 4.71 103 485 22870 -1.483 .069 .069

876 -- -- -- -- -- -- -- -- -- -- -- -- -- --

877 10.49 41 430 8698 -.147 .441 .441 13.44 32 430 7394 .732 .768 .232

878 5.41 2,898 15,666 22414578 -1.173 .121 .121 6.00 2,613 15,666 20273171 -.841 .200 .200

879 9.72 1,903 18,493 17191540 -1.737 .041 .041 11.65 1,587 18,493 14480983 -.909 .182 .182

880 8.58 26 223 2869 -.091 .464 .464 11.15 20 223 2107 -.427 .335 .335

881 7.99 2,328 18,595 22605692 3.711 1.000 0 9.62 1,933 18,595 18639920 2.830 .998 .002

882 9.41 194 1,826 172126 -.681 .248 .248 10.14 180 1,826 156056 -1.171 .121 .121

883 7.60 1,434 10,901 7695752 -1.009 .157 .157 8.83 1,235 10,901 6620980 -.998 .159 .159

884 7.85 1,737 13,631 11799548 -.238 .406 .406 9.51 1,433 13,631 9627362 -.935 .175 .175

885 8.13 3,653 29,698 55129006 1.709 .956 .044 9.48 3,133 29,698 47455866 1.946 .974 .026

886 5.50 3,884 21,366 41522266 .077 .531 .469 6.72 3,178 21,366 34017197 .192 .576 .424

887 5.08 4,941 25,079 63401202 2.837 .998 .002 6.07 4,135 25,079 53109986 2.705 .997 .003

888 6.86 2,759 18,929 27153257 3.626 1.000 0 7.70 2,460 18,929 24440771 4.273 1.000 0

889 7.00 1,961 13,726 13765943 1.753 .960 .040 8.63 1,591 13,726 11175284 1.621 .948 .052

890 7.77 1,685 13,085 10961684 -.403 .344 .344 9.30 1,407 13,085 9057233 -1.045 .148 .148

891 11.95 1,518 18,143 14912483 5.596 0 0 14.32 1,267 1,8143 12233193 3.967 1.000 0

892 11.03 655 7,226 2320685 -.859 .195 .195 13.07 553 7,226 1968800 -.595 .276 .276

893 7.57 3,560 26,939 49859054 4.111 1.000 0 9.36 2,878 26,939 39869556 2.647 .996 .004

894 6.70 840 5,631 2329896 -.746 .228 .228 8.06 699 5,631 1928266 -.925 .177 .177

895 9.74 1,753 17,071 14904134 -.284 .388 .388 12.70 1,344 17,071 11548285 .424 .664 .336

896 5.09 7,026 35,755 128275131 3.084 .999 .001 5.97 5,987 35,755 108835494 2.258 .988 .012

897 10.22 18 184 1674 .080 .532 .468 10.22 18 184 1674 .080 .532 .468

898 5.63 215 1,211 129413 -.150 .440 .440 5.74 211 1,211 127892 .026 .510 .490

899 9.67 6 58 104 -1.707 .044 .044 9.67 6 58 104 -1.707 .044 .044

900 7.58 202 1,531 163162 1.358 .913 .087 8.28 185 1,531 145443 .636 .738 .262

901 8.58 3,970 34,050 68126251 .867 .807 .193 10.35 3,290 34,050 56378525 .650 .742 .258

902 12.49 90 1,124 52546 .639 .738 .262 12.77 88 1,124 50662 .396 .654 .346

903 12.51 2,020 25,276 26390062 2.626 .996 .004 16.21 1,559 25,276 20168747 1.618 .947 .053

904 15.23 26 396 4462 -1.177 .120 .120 23.29 17 396 3422 .119 .547 .453

905 12.27 1,355 16,626 11259178 -.028 .489 .489 14.95 1,112 16,626 9320235 .476 .683 .317

906 8.27 3,826 31,631 62399609 3.345 1.000 0 9.82 3,220 31,631 51754874 1.600 .945 .055

907 -- -- -- -- -- -- -- -- -- -- -- -- -- --

908 7.74 2,556 19,782 24980541 -1.042 .149 .149 8.94 2213 19,782 22346266 1.703 .956 .044

909 8.70 965 8,392 3957273 -1.221 .111 .111 9.64 871 8,392 3581863 -1.019 .154 .154

910 11.95 593 7,085 2041759 -1.184 .118 .118 15.82 448 7,085 1551187 -.828 .204 .204

911 12.12 173 2,097 186727 .670 .749 .251 15.53 135 2,097 144421 .409 .659 .341

912 8.16 37 302 3466 -4.000 0 0 8.63 35 302 3388 -3.678 0 0

Table 3. Summary of interoccurrence intervals for daily precipitation thresholds of 0.05 and 0.10 inch—Continued

Seq.

no.

Daily precipitation threshold of 0.05 inch and greater Daily precipitation threshold of 0.10 inch and greater

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue
Table 3 81

913 7.27 884 6,422 2891414 0.960 .831 .169 8.16 787 6,422 2623246 1.850 .968 .032

914 5.64 642 3,622 1130385 -1.218 .112 .112 6.71 540 3,622 966483 -.472 .319 .319

915 5.12 6,567 33,649 113654315 4.024 1.000 0 5.95 5,659 33,649 99637122 6.059 0 0

916 5.63 3,398 19,131 33354443 2.643 .996 .004 6.11 3,130 19,131 31542673 5.187 0 0

917 7.68 1,004 7,709 3939855 .992 .839 .161 9.55 807 7,709 3026482 -1.330 .092 .092

918 4.73 1,874 8,856 8090601 -1.875 .030 .030 5.43 1,630 8,856 7143185 -.721 .235 .235

919 11.81 830 9,801 4023099 -.544 .293 .293 12.16 806 9,801 3876506 -.913 .181 .181

920 5.96 3,207 19,104 30103571 -1.696 .045 .045 6.49 2,946 19,104 28041393 -.330 .371 .371

921 8.86 493 4,368 1075744 -.035 .486 .486 9.14 478 4,368 1044590 .023 .509 .491

922 10.08 2,256 22,744 26096059 1.414 .921 .079 12.14 1,873 22,744 22079481 2.744 .997 .003

923 7.94 4,209 33,427 70205000 -.227 .410 .410 9.75 3,429 33,427 56749476 -.993 .160 .160

924 9.98 64 639 19557 -.604 .273 .273 12.06 53 639 15817 -.831 .203 .203

925 12.40 339 4,205 705640 -.318 .375 .375 14.06 299 4,205 639475 .516 .697 .303

926 5.98 93 556 25543 -.201 .420 .420 6.78 82 556 22396 -.275 .392 .392

927 6.65 667 4,433 1420726 -1.745 .040 .040 8.00 554 4,433 1186691 -1.370 .085 .085

928 7.67 994 7,623 4026714 3.432 1.000 0 9.17 831 7,623 3369287 3.183 .999 .001

929 5.51 2,850 15,716 22600020 .845 .801 .199 6.61 2,378 15,716 19004888 1.440 .925 .075

930 9.22 988 9,108 4616654 1.419 .922 .078 11.00 828 9,108 3871936 1.338 .910 .091

931 9.80 494 4,843 1172449 -.765 .222 .222 10.33 469 4,843 1134440 -.041 .484 .484

932 10.81 301 3,255 475950 -.854 .197 .197 11.15 292 3,255 457013 -1.135 .128 .128

933 20.33 3 61 58 -1.098 .136 .136 20.33 3 61 58 -1.098 .136 .136

934 6.61 839 5,547 2337033 .217 .586 .414 7.90 702 5,547 1929509 -.412 .340 .340

935 4.49 4,390 19,694 43890974 1.759 .961 .039 5.33 3,694 19,694 37063391 1.993 .977 .023

936 4.69 2,026 9,510 9520901 -.912 .181 .181 5.36 1,773 9,510 8301502 -1.117 .132 .132

937 4.86 1,836 8,920 8296647 .980 .836 .164 5.69 1,569 8,920 7011535 .135 .554 .446

938 7.49 3,379 25,311 42629455 -.314 .377 .377 9.27 2,730 25,311 34832413 .741 .771 .229

939 6.36 3,396 21,605 39977253 9.058 0 0 7.39 2,923 21,605 33465827 5.606 0 0

940 7.81 2,036 15,898 15870780 -1.513 .065 .065 9.61 1,654 15,898 12921521 -1.212 .113 .113

941 6.38 2,579 16,452 19160054 -8.520 0 0 7.85 2,097 16,452 15968551 -5.892 0 0

942 7.07 1,858 13,131 12296563 .599 .725 .275 8.42 1,559 13,131 10346810 .743 .771 .229

943 9.22 3,541 32,647 59220296 2.530 .994 .006 10.75 3,036 32,647 49822790 .510 .695 .305

944 6.17 931 5,740 2827911 3.084 .999 .001 6.78 847 5,740 2513396 1.711 .956 .044

945 7.10 3,008 21,362 31310055 -2.420 .008 .008 8.73 2,448 21,362 25645540 -1.644 .050 .050

946 5.50 1,787 9,820 9062529 2.406 .992 .008 6.41 1,531 9,820 7705028 1.693 .955 .045

947 7.32 1,882 13,784 12942634 -.163 .435 .435 8.80 1,566 13,784 10996124 1.291 .902 .098

948 6.79 179 1,216 96857 -2.550 .005 .005 9.01 135 1,216 71284 -2.647 .004 .004

949 13.48 1,967 26,509 26575843 1.486 .931 .069 17.63 1,504 26,509 20077221 .480 .684 .316

950 29.00 8 232 1135 1.093 .863 .137 29.00 8 232 1135 1.093 .863 .137

951 5.99 2,071 12,405 13510230 4.080 1.000 0 6.63 1,871 12,405 11907837 1.956 .975 .025

952 7.75 636 4,929 1574227 .190 .575 .425 8.05 612 4,929 1513291 .143 .557 .443

953 6.59 2,127 14,026 14887607 -.156 .438 .438 7.89 1,777 14,026 12560969 .579 .719 .281

954 7.59 912 6,922 2939951 -3.587 0 0 8.28 836 6,922 2724466 -2.924 .002 .002

955 8.29 3,986 33,055 69650502 6.261 0 0 9.41 3,512 33,055 60017303 3.489 1.000 0

956 7.90 4,397 34,736 80186413 5.744 0 0 9.35 3,714 34,736 66141611 2.679 .996 .004

957 6.01 713 4,283 1505704 -.642 .261 .261 6.81 629 4,283 1318564 -.917 .180 .180

958 9.49 1,322 12,543 8258763 -.244 .403 .403 10.66 1,177 12,543 7401535 .161 .564 .436

959 5.75 2,404 13,823 16989609 1.913 .972 .028 6.46 2,141 13,823 15083503 1.549 .939 .061

960 5.79 135 781 60686 3.042 .999 .001 6.56 119 781 53166 2.723 .997 .003

Table 3. Summary of interoccurrence intervals for daily precipitation thresholds of 0.05 and 0.10 inch—Continued

Seq.

no.

Daily precipitation threshold of 0.05 inch and greater Daily precipitation threshold of 0.10 inch and greater

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue
82 Atlas of Interoccurrence Intervals for Selected Thresholds of Daily Precipitation in Texas 

961 7.17 2,803 20,090 27864195 -0.951 .171 .171 8.10 2,479 20,090 25202218 1.041 .851 .149

962 13.07 55 719 23856 2.653 .996 .004 13.83 52 719 22055 2.246 .988 .012

963 8.45 135 1,141 65848 -2.919 .002 .002 10.66 107 1,141 53268 -2.282 .011 .011

964 8.33 242 2,015 229624 -1.568 .058 .058 10.08 200 2,015 195471 -.733 .232 .232

965 7.44 1,371 10,194 7763599 7.118 0 0 8.68 1,175 10,194 6522811 5.292 0 0

966 10.31 862 8,889 3912318 1.077 .859 .141 12.06 737 8,889 3329971 .781 .782 .218

967 8.68 582 5,054 1452183 -.527 .299 .299 10.94 462 5,054 1152618 -.474 .318 .318

968 5.76 275 1,583 235394 2.340 .990 .010 7.04 225 1,583 194691 2.422 .992 .008

969 5.53 220 1,217 139876 1.153 .875 .125 6.58 185 1,217 121175 1.800 .964 .036

970 6.94 4,716 32,743 76520915 -1.059 .145 .145 8.84 3,704 32,743 60379977 -.452 .326 .326

971 6.55 263 1,722 233482 .873 .809 .191 7.46 231 1,722 202738 .509 .695 .305

972 8.21 2,256 18,526 21631638 2.891 .998 .002 9.06 2,044 18,526 19630747 2.883 .998 .002

973 13.17 1,484 19,541 14753232 1.168 .879 .121 16.89 1,157 19,541 11743642 2.289 .989 .011

974 5.56 2,006 11,161 11284335 .623 .733 .267 6.41 1,742 11,161 9798918 .578 .718 .282

975 6.15 2,018 12,404 12699753 1.145 .874 .126 6.67 1,860 12,404 11271774 -1.709 .044 .044

976 7.59 117 888 55328 1.219 .889 .111 8.46 105 888 51633 1.908 .972 .028

977 7.15 13 93 736 1.359 .913 .087 7.15 13 93 736 1.359 .913 .087

978 5.85 2,284 13,354 15905475 3.556 1.000 0 7.37 1,811 13,354 12532888 2.687 .996 .004

979 5.68 1,006 5,715 2831400 -.826 .204 .204 6.97 820 5,715 2306029 -.786 .216 .216

980 7.08 505 3,573 853634 -2.095 .018 .018 8.21 435 3,573 751861 -1.175 .120 .120

981 15.00 1 15 15 1.732 .958 .042 15.00 1 15 15 1.732 .958 .042

982 8.39 46 386 9288 .543 .706 .294 9.42 41 386 8751 1.175 .880 .120

983 5.61 1,864 10,455 9527377 -1.663 .048 .048 6.17 1,696 10,455 8687533 -1.435 .076 .076

984 12.58 281 3,534 465104 -1.838 .033 .033 13.14 269 3,534 454158 -1.265 .103 .103

985 7.44 163 1,212 100705 .431 .667 .333 8.36 145 1,212 90894 .718 .763 .237

986 9.05 383 3,465 575721 -4.487 0 0 10.13 342 3,465 546671 -2.478 .007 .007

987 9.73 2,309 22,473 24854223 -3.499 0 0 10.75 2,091 2,2473 23053896 -1.489 .068 .068

988 9.69 242 2,346 241452 -4.026 0 0 9.78 240 2,346 240946 -3.867 0 0

989 5.27 3,067 16,159 23963828 -3.159 .001 .001 5.96 2,713 16,159 21351618 -2.338 .010 .010

990 6.02 3,094 18,639 30430815 5.334 0 0 6.84 2,724 18,639 26791740 5.005 0 0

991 8.69 2,137 18,574 19896150 .201 .580 .420 9.23 2,012 18,574 19052152 1.525 .936 .064

992 5.03 3,978 19,989 40518733 2.090 .982 .018 6.02 3,320 19,989 33902188 2.167 .985 .015

993 6.14 223 1,369 152709 .011 .504 .496 7.32 187 1,369 129072 .198 .579 .421

994 7.50 824 6,177 2574701 .582 .720 .280 8.84 699 6,177 2208685 1.057 .855 .145

995 7.77 2,120 16,470 18108458 2.970 .999 .001 8.57 1,921 16,470 16270459 2.164 .985 .015

996 9.37 3,079 28,850 45593368 2.551 .995 .005 11.94 2,417 28,850 35473600 1.486 .931 .069

997 9.27 2,973 27,555 42286021 3.056 .999 .001 10.00 2,756 27,555 38803527 1.994 .977 .023

998 7.49 2,849 21,324 31316699 2.863 .998 .002 8.59 2,484 21,324 27373493 2.898 .998 .002

999 6.89 530 3,649 892774 -3.060 .001 .001 8.39 435 3,649 745312 -2.201 .014 .014

1000 5.51 1,634 9,008 7040469 -3.035 .001 .001 6.37 1,415 9,008 6244410 -1.316 .094 .094

1001 6.20 3,180 19,714 32086460 2.310 .990 .010 7.22 2,732 19,714 27822505 3.003 .999 .001

1002 3.50 4 14 38 1.237 .892 .108 4.67 3 14 31 1.429 .923 .077

1003 9.03 2,255 20,356 24237862 4.610 1.000 0 10.37 1,963 20,356 21162644 4.545 1.000 0

1004 6.99 2,916 20,384 31367486 5.185 0 0 8.56 2,382 20,384 25245002 3.369 1.000 0

1005 9.78 2,182 21,346 23451150 .565 .714 .286 10.86 1,966 21,346 21020141 .136 .554 .446

1006 6.10 464 2,830 629444 -1.541 .062 .062 6.55 432 2,830 584339 -1.587 .056 .056

1007 8.51 994 8,461 4266818 .801 .788 .212 9.94 851 8,461 3565129 -.492 .312 .312

1008 5.72 2,428 13,894 16916135 .247 .598 .402 6.87 2,024 13,894 14009663 -.283 .389 .389

Table 3. Summary of interoccurrence intervals for daily precipitation thresholds of 0.05 and 0.10 inch—Continued

Seq.

no.

Daily precipitation threshold of 0.05 inch and greater Daily precipitation threshold of 0.10 inch and greater

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue
Table 3 83

1009 4.68 2,676 12,527 17110451 1.867 .969 .031 5.49 2,281 12,527 14523707 1.370 .915 .085

1010 6.09 2,571 15,655 20057145 -.294 .384 .384 7.61 2,057 15,655 16111109 .049 .519 .481

1011 8.94 2,283 20,404 23969292 2.410 .992 .008 10.40 1,962 20,404 20489465 1.814 .965 .035

1012 8.27 362 2,993 546049 .263 .604 .396 10.01 299 2,993 434144 -.891 .187 .187

1013 7.66 1,427 10,925 8097384 2.538 .994 .006 9.22 1,185 10,925 6634868 1.490 .932 .068

1014 10.60 221 2,342 269306 1.046 .852 .148 10.60 221 2,342 269306 1.046 .852 .148

1015 17.08 25 427 4670 -1.083 .139 .139 17.08 25 427 4670 -1.083 .139 .139

1016 6.21 3,226 20,037 34469537 6.544 0 0 6.95 2,885 20,037 30168616 4.073 1.000 0

1017 6.67 280 1,867 256788 -.509 .305 .305 7.95 235 1,867 222739 .408 .658 .342

1018 6.54 370 2,421 445648 -.166 .434 .434 6.67 363 2,421 436878 -.190 .424 .424

1019 8.73 924 8,062 3504693 -3.109 .001 .001 9.87 817 8,062 3163558 -1.951 .026 .026

1020 9.80 601 5,888 1782337 .312 .622 .378 10.80 545 5,888 1658374 1.358 .913 .087

1021 8.29 2,925 24,253 34975455 -1.306 .096 .096 9.64 2,517 24,253 30555427 .094 .537 .463

1022 6.41 1,541 9,875 7271280 -3.015 .001 .001 7.12 1,388 9,875 6657854 -1.840 .033 .033

1023 5.27 1,280 6,740 4244486 -.993 .160 .160 6.33 1,065 6,740 3485405 -1.632 .051 .051

1024 6.47 1,814 11,727 10340204 -2.054 .020 .020 7.33 1,600 11,727 9367879 -.101 .460 .460

1025 9.74 290 2,824 388275 -1.527 .063 .063 9.98 283 2,824 373168 -1.927 .027 .027

1026 6.28 3,045 19,114 31250963 7.061 0 0 6.97 2,743 19,114 27692905 5.115 0 0

1027 7.04 960 6,758 3333940 1.491 .932 .068 8.87 762 6,758 2672342 1.811 .965 .035

1028 8.80 3,112 27,372 43395375 1.825 .966 .034 10.09 2,712 27,372 37787345 1.630 .948 .052

1029 7.99 1,946 15,548 15211274 .420 .663 .337 8.49 1,831 15,548 14296392 .324 .627 .373

1030 6.01 2,037 12,246 11882151 -3.700 0 0 7.03 1,743 12,246 10436377 -1.599 .055 .055

1031 8.97 283 2,538 324818 -2.784 .003 .003 11.28 225 2,538 250160 -3.218 .001 .001

1032 7.05 5,166 36,443 98197689 5.377 0 0 8.34 4,371 36,443 81346587 2.445 .993 .007

1033 5.23 4,102 21,434 44662749 1.771 .962 .038 5.69 3,767 21,434 41064425 1.826 .966 .034

1034 13.28 163 2,164 186337 1.250 .894 .106 13.61 159 2,164 180346 1.055 .854 .146

1035 7.77 4,349 33,805 73976820 .727 .766 .234 9.42 3,588 33,805 60188674 -.783 .217 .217

1036 4.16 129 536 31582 -1.701 .044 .044 5.36 100 536 26350 -.291 .386 .386

1037 7.89 54 426 11556 .060 .524 .476 8.35 51 426 10959 .109 .544 .456

1038 8.51 408 3,471 727781 .973 .835 .165 8.95 388 3,471 696584 1.176 .880 .120

1039 10.86 645 7,002 2168180 -1.753 .040 .040 14.32 489 7,002 1664868 -1.054 .146 .146

1040 14.14 486 6,871 1694158 .560 .712 .288 17.99 382 6,871 1383634 1.839 .967 .033

1041 14.71 238 3,500 386568 -1.920 .027 .027 20.00 175 3,500 278448 -2.080 .019 .019

1042 4.24 2,925 12,414 18050973 -.539 .295 .295 4.96 2,505 12,414 15396707 -.847 .199 .199

1043 16.82 28 471 6376 -.303 .381 .381 17.44 27 471 5980 -.536 .296 .296

1044 8.75 936 8,188 4019438 2.592 .995 .005 11.07 740 8,188 3216754 2.911 .998 .002

1045 8.71 2,295 19,999 23808719 3.109 .999 .001 10.92 1,831 19,999 18924421 2.491 .994 .006

1046 6.25 273 1,706 234928 .253 .600 .400 7.72 221 1,706 188580 .009 .504 .496

1047 6.48 3,117 20,211 32381403 2.709 .997 .003 8.17 2,475 20,211 25998497 3.402 1.000 0

1048 6.92 1,736 12,010 10645097 1.526 .936 .064 8.82 1,361 12,010 8291649 .929 .824 .176

1049 6.43 762 4,897 1789007 -1.967 .025 .025 7.98 614 4,897 1460945 -1.211 .113 .113

1050 4.74 2,539 12,043 15686750 2.273 .988 .012 5.37 2,242 12,043 13776118 1.676 .953 .047

1051 7.89 2,265 17,865 19832655 -1.628 .052 .052 9.53 1,874 17,865 16524862 -.961 .168 .168

1052 7.24 100 724 33643 -1.223 .111 .111 9.17 79 724 27296 -.701 .242 .242

1053 4.93 212 1,044 112677 .459 .677 .323 5.38 194 1,044 100710 -.133 .447 .447

1054 12.20 5 61 112 -1.029 .152 .152 15.25 4 61 93 -.823 .205 .205

1055 6.31 530 3,344 854586 -1.421 .078 .078 6.95 481 3,344 787368 -.797 .213 .213

1056 7.08 297 2,102 357963 4.381 1.000 0 9.60 219 2,102 264650 3.840 1.000 0

Table 3. Summary of interoccurrence intervals for daily precipitation thresholds of 0.05 and 0.10 inch—Continued

Seq.

no.

Daily precipitation threshold of 0.05 inch and greater Daily precipitation threshold of 0.10 inch and greater

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue
84 Atlas of Interoccurrence Intervals for Selected Thresholds of Daily Precipitation in Texas 

1057 11.29 45 508 11386 -0.045 .482 .482 14.51 35 508 8744 -0.168 .433 .433

1058 6.23 5,658 35,247 104409758 6.136 0 0 7.40 4,762 35,247 86426063 3.565 1.000 0

1059 7.69 93 715 33200 -.024 .490 .490 9.93 72 715 25882 .081 .532 .468

1060 7.16 3,383 24,233 41601227 1.502 .933 .067 8.61 2,816 24,233 34557635 1.179 .881 .119

1061 5.74 115 660 38367 .204 .581 .419 7.42 89 660 30619 .695 .756 .244

1062 11.01 189 2,080 179527 -2.063 .020 .020 12.38 168 2,080 151846 -2.939 .002 .002

1063 12.00 1,989 23,869 25351574 5.252 0 0 14.89 1,603 23,869 19909747 2.823 .998 .002

1064 15.30 81 1,239 45573 -1.431 .076 .076 18.49 67 1,239 39761 -.596 .276 .276

1065 8.26 735 6,070 2272440 .878 .810 .190 9.18 661 6,070 2042782 .814 .792 .208

1066 6.53 1,701 11,113 9793676 2.585 .995 .005 7.38 1,506 11,113 8619687 2.021 .978 .022

1067 8.19 112 917 55833 1.600 .945 .055 9.26 99 917 49779 1.666 .952 .048

1068 7.38 97 716 33684 -.512 .304 .304 9.55 75 716 26902 .029 .512 .488

1069 7.59 714 5,418 1856957 -1.849 .032 .032 10.02 541 5,418 1424628 -1.125 .130 .130

1070 7.60 4,635 35,225 85479402 5.555 0 0 9.14 3,853 35,225 68897906 1.643 .950 .050

1071 5.25 3,742 19,631 35385361 -3.878 0 0 6.33 3,103 19,631 30638520 .573 .717 .283

1072 8.92 187 1,668 153334 -.399 .345 .345 9.64 173 1,668 138743 -.875 .191 .191

1073 30.29 7 212 911 1.044 .852 .148 35.33 6 212 699 .420 .663 .337

1074 5.40 5,577 30,105 82160970 -2.753 .003 .003 6.46 4,657 30,105 69558636 -.912 .181 .181

1075 9.48 273 2,589 351952 -.117 .453 .453 10.15 255 2,589 331761 .139 .555 .445

1076 6.49 2,781 18,047 24957862 -.497 .310 .310 8.05 2,241 18,047 20037437 -.747 .228 .228

1077 7.00 491 3,438 842329 -.077 .469 .469 8.25 417 3,438 724940 .401 .656 .344

1078 9.06 3,036 27,513 42993626 2.808 .998 .002 11.44 2,405 27,513 33612160 1.355 .912 .088

1079 7.33 4,268 31,290 69686749 4.938 1.000 0 8.67 3,611 31,290 58382046 3.478 1.000 0

1080 7.68 63 484 16965 1.550 .939 .061 8.80 55 484 14354 1.008 .843 .157

1081 7.48 2,839 21,232 30598738 1.408 .920 .080 9.04 2,350 21,232 25214480 .898 .815 .185

1082 7.46 1,836 13,695 12934267 2.139 .984 .016 9.11 1,503 13,695 10692133 2.612 .996 .005

1083 12.88 1,198 15,430 8941425 -1.953 .025 .025 15.02 1,027 15,430 7783815 -.977 .164 .164

1084 4.91 248 1,217 154880 .718 .764 .236 5.74 212 1217 128379 -.122 .451 .451

1085 5.59 6,495 36,335 122536191 5.369 0 0 6.50 5,589 36,335 103885107 2.993 .999 .001

1086 10.65 474 5,049 1363947 5.273 0 0 12.82 394 5,049 1089543 3.280 .999 .001

1087 10.02 1,402 14,050 10014586 1.090 .862 .138 12.97 1,083 14,050 7827689 1.645 .950 .050

1088 5.40 417 2,252 470189 .049 .519 .481 6.09 370 2,252 417924 .104 .542 .458

1089 13.63 87 1,186 47898 -1.156 .124 .124 14.46 82 1,186 45817 -.906 .183 .183

1090 7.53 1,352 10,180 7088091 1.910 .972 .028 8.92 1,141 10,180 5962291 1.557 .940 .060

1091 7.09 2,779 19,700 28516563 3.814 1.000 0 8.78 2,243 19,700 22685020 2.196 .986 .014

1092 3.97 31 123 1258 -3.280 .001 .001 4.39 28 123 1228 -2.629 .004 .004

1093 5.07 939 4,757 2221549 -.282 .389 .389 5.68 838 4,757 2027415 .861 .805 .195

1094 6.87 3,755 25,807 49265443 1.781 .963 .038 8.19 3,152 25,807 41038466 .877 .810 .190

1095 6.62 299 1,978 286550 -.928 .177 .177 7.19 275 1978 261280 -1.130 .129 .129

1096 8.34 2,290 19,104 22581611 2.681 .996 .004 10.31 1,853 19,104 17933376 .984 .837 .163

1097 6.44 2,954 19,028 28595807 1.646 .950 .050 7.16 2,657 19,028 26330474 3.715 1.000 0

1098 7.15 2,067 14,774 15369182 .517 .697 .303 8.45 1748 14,774 12879238 -.186 .426 .426

1099 12.12 17 206 1043 -2.888 .002 .002 15.85 13 206 788 -2.570 .005 .005

1100 7.07 399 2,820 499565 -3.876 0 0 8.22 343 2,820 431332 -3.469 0 0

1101 5.62 5,199 29,198 75605451 -.485 .314 .314 6.73 4,341 29,198 62818437 -1.001 .159 .159

1102 8.75 3,606 31,561 57159434 .466 .679 .321 10.23 3,084 31,561 48190881 -.941 .173 .173

1103 13.51 775 10,466 3923209 -1.574 .058 .058 18.01 581 10,466 2884781 -2.137 .016 .016

1104 8.02 974 7,812 4223439 5.953 0 0 8.56 913 7,812 3887049 4.709 1.000 0

Table 3. Summary of interoccurrence intervals for daily precipitation thresholds of 0.05 and 0.10 inch—Continued

Seq.

no.

Daily precipitation threshold of 0.05 inch and greater Daily precipitation threshold of 0.10 inch and greater

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue
Table 3 85

1105 5.16 2,568 13,243 17316304 1.612 .947 .053 6.28 2,108 13,243 14140596 1.040 .851 .149

1106 8.61 2,611 22,491 29713126 1.058 .855 .145 10.43 2,156 22,491 24594738 1.159 .877 .123

1107 10.26 157 1,610 123705 -.460 .323 .323 11.58 139 1,610 111852 -.008 .497 .497

1108 -- -- -- -- -- -- -- -- -- -- -- -- -- --

1109 8.67 403 3,493 680852 -1.136 .128 .128 9.68 361 3,493 601339 -1.521 .064 .064

1110 9.02 389 3,510 652583 -1.507 .066 .066 10.64 330 3,510 541506 -2.045 .020 .020

1111 7.74 291 2,252 322881 -.432 .333 .333 8.80 256 2,252 280320 -.763 .223 .223

1112 5.75 2,091 12,016 13210526 4.084 1.000 0 6.56 1,832 12,016 11391328 2.591 .995 .005

1113 7.31 4,033 29,498 59737878 .472 .681 .319 9.13 3,230 29,498 47212451 -.882 .189 .189

1114 6.25 1,939 12,124 11937611 1.190 .883 .117 7.39 1,640 12,124 10043049 .715 .763 .237

1115 9.00 646 5,813 1929108 1.208 .886 .114 10.16 572 5,813 1739928 1.929 .973 .027

1116 6.35 229 1,453 140773 -4.033 0 0 6.99 208 1,453 130865 -3.347 0 0

1117 6.04 2,605 15,727 20377142 -.463 .322 .322 7.15 2,199 15,727 17396140 .490 .688 .312

1118 6.78 118 800 48711 .602 .726 .274 7.92 101 800 42150 .754 .775 .225

1119 6.21 1,221 7,586 4713580 1.076 .859 .141 7.25 1,046 7,586 4047051 1.124 .869 .131

1120 8.12 3,011 24,462 36161380 -1.719 .043 .043 9.97 2,453 24,462 29703903 -.854 .197 .197

1121 8.39 3,539 29,675 55261746 5.400 0 0 9.57 3,101 29,675 47682613 3.504 1.000 0

1122 10.53 97 1,021 50718 .413 .660 .340 12.30 83 1,021 42042 -.123 .451 .451

1123 6.86 3,324 22,804 38954362 2.777 .997 .003 8.01 2,846 22,804 32949762 1.423 .923 .077

1124 6.04 227 1,371 151227 -.735 .231 .231 7.00 196 1371 131342 -.544 .293 .293

1125 6.93 407 2,820 600720 1.635 .949 .051 8.39 336 2,820 488979 1.020 .846 .154

1126 18.66 207 3,863 349081 -3.163 .001 .001 19.41 199 3,863 338562 -2.912 .002 .002

1127 9.99 2,672 26,696 37468553 4.525 1.000 0 11.32 2,358 26,696 32192931 1.920 .973 .027

1128 10.43 924 9,641 4360328 -1.109 .134 .134 11.29 854 9,641 4086661 -.369 .356 .356

1129 11.64 309 3,598 635278 4.348 1.000 0 13.79 261 3,598 519192 2.959 .998 .002

1130 25.17 30 755 8646 -2.244 .012 .012 25.17 30 755 8646 -2.244 .012 .012

1131 5.58 2,483 13,853 17738174 2.708 .997 .003 6.71 2,066 13,853 14652210 1.882 .970 .030

1132 11.23 62 696 23102 .965 .833 .167 13.39 52 696 20083 1.371 .915 .085

1133 6.18 1,635 10,098 8153403 -.863 .194 .194 7.67 1,316 10,098 6517221 -1.204 .114 .114

1134 8.06 85 685 29909 .437 .669 .331 9.01 76 685 26280 .145 .558 .442

1135 5.84 135 789 53791 .202 .580 .420 6.21 127 789 49459 -.250 .401 .401

1136 8.76 3,182 27,875 43161453 -2.617 .004 .004 10.66 2,616 27,875 36239669 -.537 .296 .296

1137 6.69 2,860 19,145 27823841 1.511 .935 .065 7.96 2,406 19,145 23383074 1.297 .903 .097

1138 11.59 213 2,469 250451 -1.201 .115 .115 13.00 190 2,469 221815 -1.297 .097 .097

1139 17.32 180 3,117 290092 .792 .786 .214 19.73 158 3,117 253981 .684 .753 .247

1140 7.90 1,409 11,137 7256316 -4.887 0 0 10.00 1,114 11,137 5771371 -4.025 0 0

1141 4.84 4,129 19,965 40125734 -2.949 .002 .002 5.88 3,397 19,965 33741200 -.504 .307 .307

1142 5.45 5,998 32,715 104715903 9.029 0 0 6.27 5,221 32,715 89694814 6.290 0 0

1143 10.37 869 9,015 4072374 2.025 .979 .021 12.37 729 9,015 3359485 1.046 .852 .148

1144 9.92 242 2,401 281613 -.826 .204 .204 11.17 215 2,401 257947 -.016 .494 .494

1145 11.16 128 1,429 96527 1.087 .861 .139 12.54 114 1,429 91323 2.241 .987 .013

1146 8.20 3,246 26,623 43949855 1.692 .955 .045 10.26 2,596 26,623 34883694 .835 .798 .202

1147 8.47 733 6,208 2399190 2.555 .995 .005 9.92 626 6,208 2049506 2.373 .991 .009

1148 9.65 1,347 13,000 8903592 1.075 .859 .141 10.65 1,221 13,000 8216948 2.139 .984 .016

1149 7.52 1,606 12,084 9386795 -2.265 .012 .012 8.63 1,400 12,084 8384367 -.570 .284 .284

1150 8.55 1,572 13,443 10745737 1.167 .878 .122 10.75 1,250 13,443 8490768 .648 .741 .259

1151 5.03 227 1,142 130350 .148 .559 .441 5.65 202 1,142 113934 -.301 .382 .382

1152 5.69 4,651 26,466 61647056 .193 .576 .424 7.10 3,727 26,466 49708244 .834 .798 .202

Table 3. Summary of interoccurrence intervals for daily precipitation thresholds of 0.05 and 0.10 inch—Continued

Seq.

no.

Daily precipitation threshold of 0.05 inch and greater Daily precipitation threshold of 0.10 inch and greater

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue
86 Atlas of Interoccurrence Intervals for Selected Thresholds of Daily Precipitation in Texas 

1153 4.92 99 487 22847 -0.900 .184 .184 5.73 85 487 19608 -0.841 .200 .200

1154 6.66 1,959 13,041 13061990 1.730 .958 .042 8.10 1,610 13,041 10653198 1.027 .848 .152

1155 8.25 166 1,369 94981 -3.662 0 0 8.89 154 1,369 92049 -2.725 .003 .003

1156 6.40 2,034 13,013 13414405 1.064 .856 .144 7.76 1,678 13,013 11061409 .933 .824 .176

1157 8.04 2,245 18,047 20853291 2.413 .992 .008 9.23 1,956 18,047 17992514 1.487 .931 .069

1158 6.28 567 3,562 993501 -.667 .253 .253 6.76 527 3,562 913899 -1.046 .148 .148

1159 6.05 6,087 36,849 112154577 .006 .502 .498 7.19 5,128 36,849 94484225 .004 .502 .498

1160 6.80 206 1,401 143133 -.202 .420 .420 8.44 166 1,401 115887 -.076 .470 .470

1161 11.26 508 5,720 1545133 2.479 .993 .007 12.22 468 5,720 1418915 2.252 .988 .012

1162 10.08 120 1,210 73004 .106 .542 .458 14.07 86 1,210 55293 1.007 .843 .157

1163 11.84 267 3,160 408034 -.928 .177 .177 15.57 203 3,160 301479 -1.482 .069 .069

1164 6.03 3,177 19,160 31954704 4.873 1.000 0 6.80 2,818 19,160 28148076 3.922 1.000 0

1165 8.08 1,229 9,934 6314451 2.089 .982 .018 9.65 1,030 9,934 5300719 2.007 .978 .022

1166 4.51 2,659 11,989 16222617 1.587 .944 .056 5.29 2,268 11,989 13791567 1.189 .883 .117

1167 4.63 1,457 6,751 4901659 -.221 .412 .412 5.39 1,252 6,751 4216298 -.143 .443 .443

1168 14.19 176 2,498 219469 -.037 .485 .485 15.91 157 2,498 200567 .495 .690 .310

1169 14.52 86 1,249 57809 1.227 .890 .110 16.88 74 1,249 51304 1.641 .950 .050

1170 4.60 3,596 16,537 30973352 4.331 1.000 0 5.52 2,996 16,537 25916453 4.378 1.000 0

1171 6.22 1,970 12,247 12455632 2.500 .994 .006 7.10 1,726 12,247 10585545 .112 .544 .456

1172 6.81 2,843 19,365 30559983 1.174 0 0 7.59 2,553 19,365 26797811 7.358 0 0

1173 7.28 3,265 23,783 38408747 -1.063 .144 .144 8.90 2,673 23,783 31512550 -.770 .221 .221

1174 8.27 614 5,080 1535205 -.670 .251 .251 9.60 529 5,080 1308995 -1.028 .152 .152

1175 7.35 3,689 27,125 51262238 2.587 .995 .005 8.66 3,132 27,125 43101078 1.422 .923 .077

1176 6.88 95 654 29470 -.867 .193 .193 7.79 84 654 25254 -1.280 .100 .100

1177 8.36 170 1,421 118787 -.374 .354 .354 9.87 144 1,421 101293 -.207 .418 .418

1178 8.50 2,101 17,848 19464696 3.029 .999 .001 9.33 1,914 1,7848 17860963 3.462 1.000 0

1179 7.92 2,214 17,533 19586546 .745 .772 .228 10.10 1,736 1,7533 15244408 .122 .549 .451

1180 8.82 190 1,675 159715 .089 .535 .465 11.47 146 1,675 123931 .283 .612 .388

1181 10.76 112 1,205 59132 -2.268 .012 .012 14.18 85 1,205 45506 -1.779 .038 .038

1182 4.26 2,275 9,681 10970993 -.309 .379 .379 5.11 1,896 9,681 9253891 .627 .735 .265

1183 5.15 3,811 19,606 37743021 1.098 .864 .136 5.93 3,308 19,606 32712267 .872 .808 .192

1184 12.12 663 8,033 2520689 -2.382 .009 .009 16.74 480 8,033 1814991 -2.223 .013 .013

1185 7.45 1,148 8,556 5073020 1.934 .973 .027 8.28 1,033 8,556 4477877 .740 .770 .230

1186 4.55 1,325 6,027 4028825 .568 .715 .285 5.45 1,106 6,027 3369924 .639 .739 .261

1187 4.21 2,728 11,476 15650784 -.014 .494 .494 5.06 2,266 1,1476 12966438 -.228 .410 .410

1188 12.85 779 10,006 3974730 .960 .831 .169 16.99 589 10,006 2986512 .567 .715 .285

1189 9.69 1,978 19,158 17919666 -4.178 0 0 10.87 1,762 19,158 16322539 -2.394 .008 .008

1190 5.80 3,289 19,072 32256634 2.827 .998 .002 6.36 3,001 19,072 29532824 3.035 .999 .001

1191 9.40 77 724 27495 -.207 .418 .418 14.78 49 724 15806 -1.321 .093 .093

1192 7.88 823 6,484 2743986 1.412 .921 .079 9.82 660 6,484 2205574 1.370 .915 .085

1193 6.58 1,160 7,637 4812886 5.107 0 0 7.52 1,015 7,637 4050545 2.488 .994 .006

1194 6.01 1,386 8,332 5405846 -4.112 0 0 6.90 1,207 8,332 4827845 -2.400 .008 .008

1195 4.51 493 2,224 555427 .506 .694 .307 5.30 420 2,224 481255 1.080 .860 .140

1196 5.10 1,260 6,424 4101117 .820 .794 .206 6.09 1,055 6,424 3438926 .835 .798 .202

1197 5.97 3,318 19,815 34108976 3.751 1.000 0 7.06 2,807 19,815 28615521 2.657 .996 .004

1198 8.60 1,056 9,076 4971011 2.101 .982 .018 10.29 882 9,076 4172383 2.183 .985 .015

1199 21.18 17 360 3708 1.512 .935 .065 24.00 15 360 2996 .735 .769 .231

1200 7.70 1,869 14,391 13475945 .153 .561 .439 8.97 1,604 14,391 11592688 .307 .621 .379

Table 3. Summary of interoccurrence intervals for daily precipitation thresholds of 0.05 and 0.10 inch—Continued

Seq.

no.

Daily precipitation threshold of 0.05 inch and greater Daily precipitation threshold of 0.10 inch and greater

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue
Table 3 87

1201 9.35 205 1,917 205821 1.177 .880 .120 11.15 172 1,917 166516 0.228 .590 .410

1202 7.76 2,501 19,400 25257880 3.564 1.000 0 9.76 1,987 19,400 20009484 2.947 .998 .002

1203 8.83 1,778 15,694 13392232 -2.930 .002 .002 9.85 1,594 15,694 11943357 -3.122 .001 .001

1204 7.93 1,952 15,481 15575438 2.360 .991 .009 9.45 1,639 15,481 13259403 3.166 .999 .001

1205 4.75 1,366 6,485 4426426 -.041 .484 .484 5.64 1,149 6,485 3714284 -.179 .429 .429

1206 4.90 2,160 10,592 11437784 -.011 .496 .496 5.86 1,809 10,592 9576800 -.028 .489 .489

1207 5.44 1,123 6,104 3412483 -.253 .400 .400 6.42 951 6,104 2862646 -.733 .232 .232

1208 8.51 2,291 19,506 22057443 -1.064 .144 .144 10.44 1,869 19,506 18140326 -.362 .359 .359

1209 -- -- -- -- -- -- -- -- -- -- -- -- -- --

1210 7.30 508 3,709 901421 -1.685 .046 .046 8.06 460 3,709 823965 -1.267 .103 .103

1211 7.86 3,571 28,061 51428876 2.739 .997 .003 10.02 2,801 28,061 39345794 .108 .543 .457

1212 7.68 1,254 9,634 6174615 1.362 .913 .087 9.67 996 9,634 4816831 .218 .586 .414

1213 7.17 763 5,474 1929463 -3.640 0 0 9.02 607 5,474 1586068 -1.934 .027 .027

1214 10.65 68 724 22456 -1.253 .105 .105 10.65 68 724 22456 -1.253 .105 .105

1215 9.06 942 8,537 3813266 -2.746 .003 .003 11.70 730 8,537 2972952 -2.148 .016 .016

1216 9.94 2,539 25,234 33506668 4.011 1.000 0 12.04 2,096 25,234 27091363 1.937 .974 .026

1217 6.56 2,003 13,130 13018720 -.772 .220 .220 7.57 1,734 13,130 11161743 -1.406 .080 .080

1218 8.38 390 3,269 630405 -.378 .353 .353 8.69 376 3,269 605791 -.480 .316 .316

1219 6.18 3,176 19,632 30855257 -1.003 .158 .158 6.98 2,811 19,632 27708758 .386 .650 .350

1220 10.90 1,918 20,914 20873200 3.089 .999 .001 14.35 1,457 20,914 15756112 2.258 .988 .012

1221 11.99 490 5,877 1518327 2.089 .982 .018 12.56 468 5,877 1439562 1.753 .960 .040

1222 9.96 23 229 2416 -.686 .246 .246 10.91 21 229 2257 -.487 .313 .313

1223 5.55 987 5,476 2699826 -.052 .479 .479 6.88 796 5,476 2180974 .034 .514 .486

1224 7.22 274 1,978 269687 -.137 .445 .445 7.67 258 1,978 255324 .018 .507 .493

1225 6.08 436 2,649 590763 .832 .797 .203 7.70 344 2,649 471374 1.110 .866 .134

1226 7.55 2,902 21,901 30920047 -2.520 .006 .006 9.41 2,328 21,901 24462941 -3.376 0 0

1227 8.31 752 6,246 2440231 1.855 .968 .032 8.31 752 6,246 2440231 1.855 .968 .032

1228 7.75 3,237 25,070 41667598 2.652 .996 .004 9.08 2,761 25,070 35605063 2.619 .996 .004

1229 5.58 2,647 14,762 19922369 1.755 .960 .040 6.84 2,159 14,762 16245263 1.564 .941 .059

1230 5.70 2,518 14,360 18442939 1.748 .960 .040 6.88 2,088 14,360 15033930 .222 .588 .412

1231 5.90 132 779 54377 1.147 .874 .126 6.66 117 779 47521 .802 .789 .211

1232 5.57 175 975 89621 1.157 .876 .124 6.37 153 975 77987 .977 .836 .164

1233 5.84 911 5,323 2483701 1.274 .899 .101 7.71 690 5,323 1864474 .695 .756 .244

1234 8.70 1,284 11,164 7277535 .955 .830 .170 9.47 1,179 11,164 6747430 1.502 .933 .067

1235 6.23 665 4,140 1324900 -1.676 .047 .047 7.61 544 4,140 1120021 -.217 .414 .414

1236 8.56 259 2,216 259893 -2.630 .004 .004 10.12 219 2,216 223963 -1.974 .024 .024

1237 5.52 2,383 13,142 16221905 3.041 .999 .001 6.70 1,962 13,142 13343706 2.686 .996 .004

1238 6.06 4,202 25,474 53297285 -.469 .320 .320 7.42 3,434 25,474 43993127 .590 .722 .278

1239 7.03 2,141 15,049 18016227 9.483 0 0 7.81 1,928 15,049 15739015 6.458 0 0

1240 9.16 205 1,877 186688 -.735 .231 .231 10.04 187 1,877 168561 -.936 .175 .175

1241 6.41 2,819 18,072 26273138 2.891 .998 .002 6.78 2,666 18,072 25011556 3.421 1.000 0

1242 7.47 100 747 38782 .664 .747 .253 8.49 88 747 33728 .425 .665 .335

1243 4.32 4,075 17,604 36090543 .686 .753 .247 5.08 3,464 17,604 30662073 .575 .717 .283

1244 5.42 3,537 19,152 34619275 2.278 .989 .011 6.35 3,016 19,152 29568760 2.264 .988 .012

1245 9.33 2,032 18,958 20808139 6.270 0 0 11.01 1,722 18,958 17371302 4.617 1.000 0

1246 12.11 191 2,312 215734 -.549 .292 .292 13.60 170 2,312 188283 -.947 .172 .172

1247 9.09 1,671 15,182 12819983 .756 .775 .225 10.09 1,504 15,182 11376462 -.238 .406 .406

1248 3.81 16 61 501 .185 .573 .427 4.36 14 61 448 .319 .625 .375

Table 3. Summary of interoccurrence intervals for daily precipitation thresholds of 0.05 and 0.10 inch—Continued

Seq.

no.

Daily precipitation threshold of 0.05 inch and greater Daily precipitation threshold of 0.10 inch and greater

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue
88 Atlas of Interoccurrence Intervals for Selected Thresholds of Daily Precipitation in Texas 

1249 6.73 1,833 12,327 12052215 4.953 1.000 0 7.62 1,617 12,327 10218928 1.765 .961 .039

1250 6.19 5,950 36,857 114409263 5.800 0 0 7.01 5,260 36,857 100021270 4.001 1.000 0

1251 6.48 171 1,108 92020 -.649 .258 .258 8.27 134 1,108 71364 -.776 .219 .219

1252 6.14 5,774 35,470 102970077 .730 .767 .233 7.45 4,762 35,470 85554385 1.557 .940 .060

1253 8.44 529 4,465 1264979 2.833 .998 .002 8.51 525 4,465 1263113 3.083 .999 .001

1254 7.73 59 456 14729 1.263 .897 .103 8.00 57 456 13934 .944 .827 .173

1255 6.26 2,146 13,428 14736233 1.827 .966 .034 7.60 1,767 13,428 11868367 .029 .512 .488

1256 9.10 2,251 20,473 22234499 -2.881 .002 .002 10.52 1,946 20,473 19122856 -3.058 .001 .001

1257 7.45 2,622 19,529 26447262 2.926 .998 .002 9.70 2,013 19,529 20320816 2.629 .996 .004

1258 7.31 497 3,633 868075 -1.485 .069 .069 7.43 489 3,633 855573 -1.410 .079 .079

1259 12.05 19 229 2205 .102 .541 .459 19.08 12 229 1432 .253 .600 .400

1260 5.31 4,103 21,784 46392280 4.226 1.000 0 6.41 3,399 21,784 38054634 2.817 .998 .002

1261 9.25 884 8,179 3487271 -1.821 .034 .034 10.60 772 8,179 3051769 -1.606 .054 .054

1262 7.17 161 1,154 90273 -.621 .267 .267 8.30 139 1,154 79196 -.256 .399 .399

1263 3.61 143 516 38269 .772 .780 .220 4.10 126 516 33856 .806 .790 .210

1264 9.50 163 1,548 128129 .345 .635 .365 11.30 137 1,548 104320 -.329 .371 .371

1265 5.27 656 3,454 1063258 -2.728 .003 .003 6.01 575 3,454 962668 -1.270 .102 .102

1266 5.96 3,193 19,044 31535334 3.643 1.000 0 7.24 2,629 19,044 25845444 2.881 .998 .002

1267 8.08 1,669 13,484 12312156 6.664 0 0 9.31 1,448 13,484 10434938 4.540 1.000 0

1268 9.37 1,832 17,161 17210360 7.031 0 0 10.26 1,672 17,161 15391507 5.158 0 0

1269 -- -- -- -- -- -- -- -- -- -- -- -- -- --

1270 7.15 306 2,187 332022 -.234 .407 .407 8.28 264 2,187 280991 -.750 .227 .227

1271 7.19 4,878 35,073 88460355 4.126 1.000 0 8.49 4,130 3,5073 73632358 1.854 .968 .032

1272 8.75 456 3,991 840909 -2.806 .003 .003 9.57 417 3,991 761498 -3.002 .001 .001

1273 7.19 1,325 9,529 6461610 1.485 .931 .069 8.91 1,069 9,529 5190285 1.079 .860 .140

1274 6.56 938 6,153 2834703 -.939 .174 .174 6.67 923 6,153 2807565 -.594 .276 .276

1275 4.15 868 3,606 1518312 -1.523 .064 .064 5.00 721 3,606 1246277 -1.921 .027 .027

1276 4.93 1,121 5,527 3160923 1.180 .881 .119 5.98 925 5,527 2577425 .437 .669 .331

1277 8.62 297 2,560 305805 -5.838 0 0 9.08 282 2,560 301889 -4.760 0 0

1278 5.30 5,473 28,977 82475557 5.139 0 0 6.16 4,707 28,977 69839853 2.862 .998 .002

1279 11.04 136 1,501 97034 -.996 .160 .160 13.90 108 1,501 77223 -.851 .198 .198

1280 7.21 746 5,379 2065465 1.394 .918 .082 8.57 628 5,379 1772385 2.143 .984 .016

1281 5.60 1,108 6,203 3324177 -1.884 .030 .030 6.42 966 6,203 2927917 -1.224 .110 .110

1282 6.13 40 245 5710 1.811 .965 .035 8.45 29 245 4550 2.619 .996 .004

1283 11.13 470 5,233 1230427 .021 .508 .492 11.66 449 5,233 1155037 -.618 .268 .268

1284 5.99 1,631 9,769 7983568 .149 .559 .441 6.43 1,520 9,769 7469979 .414 .661 .339

1285 11.31 1,862 21,056 19637509 .131 .552 .448 14.81 1,422 21,056 14986039 .066 .527 .473

1286 6.10 3,001 18,295 28592610 3.944 1.000 0 6.70 2,732 18,295 25842393 3.084 .999 .001

1287 9.26 646 5,980 1921410 -.231 .409 .409 12.48 479 5,980 1419294 -.342 .366 .366

1288 7.87 1,531 12,048 8742941 -3.526 0 0 9.43 1,278 12,048 7394052 -2.450 .007 .007

1289 9.33 1,487 13,868 11016237 4.569 1.000 0 10.40 1,333 13,868 9638311 2.704 .997 .003

1290 9.60 149 1,430 105232 -.259 .398 .398 10.07 142 1,430 101211 -.065 .474 .474

1291 6.79 179 1,216 108509 -.069 .473 .473 8.11 150 1,216 88307 -.673 .251 .251

1292 5.62 3,499 19,665 36151173 5.203 0 0 6.43 3,060 19,665 31212651 3.583 1.000 0

1293 6.95 2,451 17,041 22022416 4.675 1.000 0 7.98 2,136 17,041 18752275 2.430 .992 .008

1294 7.62 664 5,058 1665393 -.369 .356 .356 8.77 577 5,058 1433329 -.739 .230 .230

1295 5.80 110 638 38405 1.716 .957 .043 6.38 100 638 35309 1.851 .968 .032

1296 4.22 1,009 4,257 2105442 -1.081 .140 .140 4.83 882 4,257 1871681 -.155 .438 .438

Table 3. Summary of interoccurrence intervals for daily precipitation thresholds of 0.05 and 0.10 inch—Continued

Seq.

no.

Daily precipitation threshold of 0.05 inch and greater Daily precipitation threshold of 0.10 inch and greater

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue
Table 3 89

1297 8.02 338 2,709 398169 -4.149 0 0 9.92 273 2,709 308664 -4.730 0 0

1298 4.97 299 1,485 206933 -2.034 .021 .021 6.09 244 1,485 168484 -1.895 .029 .029

1299 4.63 2,096 9,696 10204793 .339 .633 .367 5.44 1,784 9,696 8703021 .458 .677 .323

1300 5.87 31 182 3458 2.178 .985 .015 7.00 26 182 2895 1.975 .976 .024

1301 5.74 4,838 27,787 69474491 4.047 1.000 0 6.90 4,029 27,787 57537777 3.066 .999 .001

1302 6.39 2,924 18,695 28232680 3.086 .999 .001 7.51 2,488 18,695 23868599 2.274 .989 .011

1303 10.78 27 291 3603 -.746 .228 .228 10.78 27 291 3603 -.746 .228 .228

1304 6.80 535 3,640 928215 -1.872 .031 .031 7.47 487 3,640 853806 -1.403 .080 .080

1305 12.92 1,753 22,655 21686985 6.683 0 0 17.69 1,281 22,655 15700225 5.083 0 0

1306 9.78 1,531 14,972 12092729 3.735 1.000 0 12.38 1,209 14,972 9402072 2.339 .990 .010

Table 3. Summary of interoccurrence intervals for daily precipitation thresholds of 0.05 and 0.10 inch—Continued

Seq.

no.

Daily precipitation threshold of 0.05 inch and greater Daily precipitation threshold of 0.10 inch and greater

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue
90 Atlas of Interoccurrence Intervals for Selected Thresholds of Daily Precipitation in Texas 

Table 4

Table 4. Summary of interoccurrence intervals for daily precipitation thresholds of 0.25 and 0.50 inch—Continued

Seq.

no.

Daily precipitation threshold of 0.25 inch and greater Daily precipitation threshold of 0.50 inch and greater

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue

1 16.64 1,173 19,514 11806259 1.873 .969 .031 29.26 667 19,514 6772781 1.821 .966 .034

2 12.63 19 240 2143 -.454 .325 .325 30.00 8 240 753 -1.056 .145 .145

3 14.14 1,395 19,720 14068377 1.475 .930 .070 23.37 844 19,720 8411682 .543 .706 .294

4 15.97 527 8,416 2185242 -.581 .281 .281 26.30 320 8,416 1351736 .119 .547 .453

5 18.09 1,050 18,993 10342772 2.091 .982 .018 29.91 635 18,993 6420769 2.826 .998 .002

6 18.16 194 3,522 341170 -.033 .487 .487 29.85 118 3,522 193727 -1.274 .101 .101

7 12.19 678 8,264 2834925 .538 .705 .295 18.53 446 8,264 1867625 .491 .688 .312

8 15.19 96 1,458 62185 -1.891 .029 .029 23.90 61 1,458 41079 -1.031 .151 .151

9 13.65 212 2,893 291841 -1.219 .112 .112 23.33 124 2,893 162202 -1.846 .032 .032

10 9.73 22 214 2446 .318 .625 .375 14.27 15 214 1620 .063 .525 .475

11 19.07 321 6,120 1059378 2.436 .993 .007 27.20 225 6,120 755291 2.520 .994 .006

12 12.75 2,791 35,581 50239187 1.080 .860 .140 20.38 1,746 35,581 31260530 .462 .678 .322

13 10.09 1,487 15,005 11419981 1.579 .943 .057 15.91 943 15,005 7455537 2.862 .998 .002

14 13.98 2,144 29,966 32027188 -.241 .405 .405 22.65 1,323 29,966 20259481 1.389 .918 .082

15 19.64 87 1,709 69301 -1.095 .137 .137 31.65 54 1,709 37274 -2.446 .007 .007

16 20.50 6 123 174 -2.242 .012 .012 24.60 5 123 148 -2.009 .022 .022

17 17.57 7 123 376 -.580 .281 .281 30.75 4 123 287 .577 .718 .282

18 18.73 1,470 27,539 20451213 .689 .755 .245 36.05 764 27,539 10552616 .149 .559 .441

19 8.29 2,322 19,240 23093085 2.823 .998 .002 12.73 1,512 19,240 15192106 2.994 .999 .001

20 11.13 550 6,122 1746028 1.508 .934 .066 16.24 377 6,122 1205149 1.491 .932 .068

21 9.50 556 5,279 1460310 -.202 .420 .420 14.00 377 5,279 966605 -.963 .168 .168

22 8.27 4,175 34,541 73773233 2.590 .995 .005 12.17 2,838 34,541 49572012 1.051 .853 .147

23 12.50 95 1,187 56387 .001 .501 .499 18.84 63 1,187 39704 .851 .802 .198

24 16.26 1,211 19,693 11997837 .373 .645 .355 29.31 672 19,693 6749175 .898 .815 .185

25 19.38 710 13,756 4715386 -1.588 .056 .056 33.39 412 13,756 2711255 -1.520 .064 .064

26 7.71 4,034 31,099 63244216 .908 .818 .182 11.40 2,727 31,099 42763577 .768 .779 .221

27 9.18 2,265 20,787 23411983 -.453 .325 .325 14.06 1,478 20,787 14973810 -1.681 .046 .046

28 10.35 1,162 12,022 7064673 .675 .750 .250 16.72 719 12,022 4375563 .577 .718 .282

29 20.16 788 15,884 6245909 -.096 .462 .462 36.35 437 15,884 3379366 -.952 .171 .171

30 8.09 3,912 31,631 63422175 2.717 .997 .003 12.06 2,622 31,631 43253940 3.819 1.000 0

31 9.27 1,956 18,129 18118286 1.677 .953 .047 14.16 1,280 18,129 11948176 1.846 .968 .032

32 13.17 1,264 16,648 10568153 .273 .608 .392 20.58 809 16,648 6721474 -.093 .463 .463

33 11.66 1,988 23,183 23703520 2.211 .986 .014 19.00 1,220 23,183 14402811 1.117 .868 .132

34 10.32 351 3,622 627829 -.400 .345 .345 15.68 231 3,622 415810 -.159 .437 .437

35 12.77 806 10,292 4428495 3.329 1.000 0 19.27 534 10,292 2959481 3.081 .999 .001

36 10.53 1,052 11,081 5859005 .293 .615 .385 16.25 682 11,081 3677528 -1.210 .113 .113

37 11.37 960 10,911 5257240 .205 .581 .419 17.00 642 10,911 3493800 -.108 .457 .457

38 12.17 1,842 22,410 21390559 2.705 .997 .003 19.24 1,165 22,410 13679506 2.834 .998 .002

39 10.11 1,933 19,535 19504127 2.515 .994 .006 15.12 1,292 19,535 13313065 3.421 1.000 0

40 13.01 798 10,379 4309625 1.990 .977 .023 20.04 518 10,379 2842382 2.262 .988 .012

41 8.57 2,894 24,787 36818466 2.472 .993 .007 12.94 1,916 24,787 24216102 1.501 .933 .067

42 15.50 48 744 17628 -.153 .439 .439 24.80 30 744 10402 -.644 .260 .260

43 14.50 2,213 32,082 35996658 1.143 .873 .127 23.28 1,378 32,082 22401537 .864 .806 .194

44 9.29 2,115 19,656 21382488 2.285 .989 .011 13.98 1,406 19,656 14416523 2.812 .998 .002

45 7.82 2,423 18,947 22767753 -.693 .244 .244 11.81 1,604 18,947 15458465 1.201 .885 .115

46 11.06 2,337 25,853 30536963 .908 .818 .182 17.66 1,464 25,853 19009646 .299 .617 .383

47 12.60 505 6363 1683340 1.858 .968 .032 20.20 315 6,363 1053327 1.569 .942 .058

48 12.20 463 5648 1318165 .304 .619 .381 19.82 285 5,648 834700 1.085 .861 .139

49 7.95 38 302 6803 1.982 .976 .024 12.58 24 302 4536 2.135 .984 .016

50 11.02 83 915 43676 2.370 .991 .009 16.64 55 915 30299 2.622 .996 .004

51 11.00 1,656 18,223 15353649 1.238 .892 .108 17.81 1,023 18,223 9424557 .615 .731 .269

52 9.38 1,398 13,109 9135011 -.199 .421 .421 13.92 942 13,109 6187999 .118 .547 .453

Table 4. Summary of interoccurrence intervals for daily precipitation thresholds of 0.25 and 0.50 inch

[--, not available, no events that equal or exceed the threshold were observed]
Table 4 91

53 6.25 49 306 7473 -.039 .485 .485 8.74 35 306 5189 -.318 .375 .375

54 21.75 4 87 152 -.438 .331 .331 29.00 3 87 96 -.793 .214 .214

55 13.86 712 9,865 3585487 .968 .833 .167 21.83 452 9,865 2201243 -.467 .320 .320

56 17.28 138 2,385 177927 1.652 .951 .049 27.73 86 2,385 107127 .716 .763 .237

57 22.98 852 19,579 8453534 .684 .753 .247 41.75 469 19,579 4743693 1.245 .893 .107

58 16.00 38 608 11213 -.313 .377 .377 24.32 25 608 5748 -2.110 .017 .017

59 14.26 2,540 36,226 45885260 -.231 .409 .409 23.24 1,559 36,226 27648184 -1.429 .077 .077

60 19.09 22 420 4754 .236 .593 .407 38.18 11 420 1955 -.883 .189 .189

61 22.26 1,252 27,865 17451071 .027 .511 .489 48.46 575 27,865 8425456 2.148 .984 .016

62 21.80 10 218 1445 1.784 .963 .037 27.25 8 218 1156 1.596 .945 .055

63 18.88 108 2,039 125975 2.594 .995 .005 28.72 71 2,039 86292 2.804 .997 .003

64 73.75 4 295 628 .223 .588 .412 -- -- -- -- -- -- --

65 12.03 617 7,422 2249965 -.746 .228 .228 19.13 388 7,422 1463106 .551 .709 .291

66 13.57 172 2,334 189826 -1.233 .109 .109 20.47 114 2,334 121481 -1.607 .054 .054

67 9.61 1,388 13,340 9392184 .936 .825 .175 14.81 901 13,340 6176756 1.446 .926 .074

68 21.38 245 5,237 656241 .622 .733 .267 36.12 145 5,237 382412 .150 .560 .440

69 26.72 184 4,917 430401 -1.141 .127 .127 46.39 106 4,917 255716 -.334 .369 .369

70 12.48 83 1,036 51296 3.047 .999 .001 16.98 61 1,036 38609 3.002 .999 .001

71 11.91 64 762 24510 .072 .529 .471 18.14 42 762 15037 -.677 .249 .249

72 13.82 316 4,366 676963 -.574 .283 .283 22.74 192 4,366 425957 .391 .652 .348

73 15.55 804 12,503 4972848 -.521 .301 .301 23.77 526 12,503 3429382 1.705 .956 .044

74 9.44 128 1,208 78578 .321 .626 .374 14.73 82 1,208 52064 .803 .789 .211

75 8.87 2,641 23,435 31848135 2.595 .995 .005 13.66 1,716 23,435 21065521 3.420 1.000 0

76 21.77 53 1154 26477 -1.692 .045 .045 37.23 31 1,154 15746 -1.154 .124 .124

77 7.86 2,014 15,838 16380544 2.104 .982 .018 11.36 1,394 15,838 11275282 1.384 .917 .083

78 14.48 50 724 18643 .367 .643 .357 21.29 34 724 12441 .109 .543 .457

79 9.40 62 583 20776 2.040 .979 .021 13.88 42 583 13946 1.561 .941 .059

80 7.29 4,881 35,599 89162036 3.179 .999 .001 10.97 3,244 35,599 59449459 2.918 .998 .002

81 7.39 1,911 14,126 14070741 3.216 .999 .001 11.18 1,263 14,126 9360225 3.034 .999 .001

82 8.98 1,411 12,671 9647209 5.152 0 0 12.61 1,005 12,671 6786390 3.615 1.000 0

83 12.06 2,955 35,650 53468681 1.423 .923 .077 19.72 1,808 35,650 32727788 1.143 .873 .127

84 9.00 868 7,812 3444851 .819 .794 .206 13.52 578 7,812 2279660 .406 .657 .343

85 11.18 148 1,655 118935 -.608 .272 .272 14.27 116 1,655 93066 -.568 .285 .285

86 10.59 1,365 14,452 10326222 3.002 .999 .001 17.02 849 14,452 6582640 3.684 1.000 0

87 18.95 64 1,213 37493 -.472 .318 .318 28.88 42 1,213 24242 -.543 .294 .294

88 15.43 833 12,853 5302457 -.475 .318 .318 23.54 546 12,853 3510940 .024 .510 .490

89 10.90 1,750 19,069 17381359 3.022 .999 .001 16.97 1,124 19,069 11213725 2.693 .996 .004

90 13.18 485 6,392 1493877 -1.383 .083 .083 20.69 309 6,392 995523 .245 .597 .403

91 13.88 894 12,411 5479083 -.641 .261 .261 23.51 528 12,411 3170343 -1.290 .099 .099

92 10.72 1,155 12,385 7093274 -.486 .313 .313 16.54 749 12,385 4585373 -.540 .295 .295

93 7.35 289 2,124 304913 -.192 .424 .424 10.78 197 2,124 210678 .170 .568 .432

94 26.77 91 2,436 108361 -.369 .356 .356 45.96 53 2,436 59335 -1.019 .154 .154

95 18.46 56 1,034 28629 -.145 .442 .442 24.62 42 1,034 20391 -.684 .247 .247

96 17.85 773 13,801 5227829 -.959 .169 .169 30.00 460 13,801 3118275 -.655 .256 .256

97 26.26 43 1,129 23438 -.391 .348 .348 53.76 21 1,129 10270 -1.061 .144 .144

98 17.85 1,067 19,044 10612246 2.519 .994 .006 30.52 624 19,044 6371276 3.128 .999 .001

99 11.40 10 114 451 -1.144 .126 .126 22.80 5 114 255 -.408 .342 .342

100 17.45 1,638 28,580 23239089 -.503 .308 .308 26.79 1,067 28,580 15586439 1.258 .896 .104

101 14.28 645 9,211 2908953 -0.912 .181 .181 22.80 404 9,211 1800720 -1.121 .131 .131

102 11.46 69 791 30080 1.471 .929 .071 17.98 44 791 19378 1.305 .904 .096

103 10.93 3,427 37,448 66080651 3.024 .999 .001 17.06 2,195 37,448 42067271 1.911 .972 .028

104 13.79 455 6,276 1468970 1.066 .857 .143 20.99 299 6,276 982929 1.426 .923 .077

Table 4. Summary of interoccurrence intervals for daily precipitation thresholds of 0.25 and 0.50 inch—Continued

Seq.

no.

Daily precipitation threshold of 0.25 inch and greater Daily precipitation threshold of 0.50 inch and greater

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue
92 Atlas of Interoccurrence Intervals for Selected Thresholds of Daily Precipitation in Texas 

105 15.98 641 10,246 3334314 .674 .750 .250 24.99 410 10,246 2115082 .245 .597 .403

106 14.60 244 3,562 425091 -.590 .278 .278 26.99 132 3,562 222409 -1.074 .142 .142

107 10.04 746 7,487 2752395 -.682 .248 .248 15.06 497 7,487 1897107 .759 .776 .224

108 11.35 3,290 37,342 62971259 2.497 .994 .006 17.62 2,119 37,342 40144767 1.171 .879 .121

109 7.12 2,025 14,412 14796772 1.093 .863 .137 10.14 1,421 14,412 10617602 2.410 .992 .008

110 8.68 4,000 34,710 70675099 1.981 .976 .024 13.27 2,616 34,710 46900647 2.927 .998 .002

111 11.51 109 1,254 71666 .879 .810 .190 17.91 70 1,254 44951 .350 .637 .363

112 14.36 1,599 22,955 18159960 -.727 .234 .234 25.71 893 22,955 10163197 -.435 .332 .332

113 15.42 156 2,405 159760 -3.209 .001 .001 25.32 95 2,405 98207 -2.369 .009 .009

114 19.29 104 2,006 105681 .232 .592 .408 35.19 57 2,006 61906 1.083 .861 .139

115 30.88 585 18,062 5499764 1.718 .957 .043 64.28 281 18,062 2597827 .688 .754 .246

116 15.36 378 5,805 1064144 -1.013 .156 .156 26.75 217 5,805 643919 .570 .716 .284

117 14.76 1,302 19,214 12927752 2.096 .982 .018 26.04 738 19,214 7227077 .910 .818 .182

118 15.32 66 1,011 37623 1.797 .964 .036 28.08 36 1,011 19078 .503 .692 .308

119 10.84 2,544 27,586 36306505 3.030 .999 .001 16.96 1,627 27,586 23435388 3.095 .999 .001

120 7.58 2,530 19,175 24818102 2.018 .978 .022 11.40 1,682 19,175 16643703 2.280 .989 .011

121 10.97 1,673 18,359 15831860 2.189 .986 .014 16.65 1,103 18,359 10777679 3.708 1.000 0

122 17.08 506 8,643 2290400 1.848 .968 .032 28.25 306 8,643 1375845 1.225 .890 .110

123 16.84 2,049 34,510 35312060 -.096 .462 .462 26.03 1,326 34,510 23062896 .504 .693 .307

124 17.64 428 7,550 1829463 4.741 1.000 0 25.34 298 7,550 1235776 2.946 .998 .002

125 13.27 1,788 23,727 21741718 1.829 .966 .034 21.61 1,098 23,727 13437696 1.813 .965 .035

126 9.47 382 3,619 681725 -.466 .321 .321 13.87 261 3,619 475198 .173 .569 .431

127 17.97 1,079 19,385 10694785 1.287 .901 .099 32.86 590 19,385 5660381 -.428 .334 .334

128 8.29 1,313 10,885 7204759 .516 .697 .303 12.44 875 10,885 4771543 .101 .540 .460

129 11.53 1,703 19,634 16944958 .969 .834 .166 17.52 1,121 19,634 11098032 .491 .688 .312

130 12.89 2,045 26,350 26930065 -.037 .485 .485 21.55 1,223 26,350 16282048 .635 .737 .263

131 11.89 64 761 27211 1.627 .948 .052 19.51 39 761 16349 1.100 .864 .136

132 9.63 1,458 14,041 10524859 1.867 .969 .031 14.46 971 14,041 6890429 .582 .720 .280

133 9.16 3,962 36,302 73002260 1.649 .950 .050 14.32 2,536 36,302 46848968 1.550 .939 .061

134 15.41 78 1,202 41260 -1.833 .033 .033 25.04 48 1,202 24446 -1.831 .034 .034

135 12.94 94 1,216 52259 -1.438 .075 .075 22.52 54 1,216 31064 -.685 .247 .247

136 10.90 2,847 31,019 44801802 1.353 .912 .088 17.15 1,809 31,019 28552016 1.301 .903 .097

137 11.28 313 3,532 569648 .936 .825 .175 16.58 213 3,532 399794 1.588 .944 .056

138 15.02 509 7,647 1955572 .189 .575 .425 22.29 343 7,647 1373221 1.511 .935 .065

139 20.43 7 143 641 1.286 .901 .099 47.67 3 143 368 2.147 .984 .016

140 10.24 126 1,290 86690 1.297 .903 .097 14.33 90 1,290 60441 .677 .751 .249

141 7.62 1,400 10,670 7636745 1.456 .927 .073 11.51 927 10,670 5036177 .966 .833 .167

142 7.57 1,061 8,028 4303608 .593 .723 .277 11.07 725 8,028 3001616 1.466 .929 .071

143 7.64 2,353 17,968 21613560 1.885 .970 .030 10.92 1,646 17,968 15005660 1.036 .850 .150

144 16.69 825 13,768 5325657 -3.098 .001 .001 28.86 477 13,768 3060309 -2.573 .005 .005

145 18.18 961 17,470 8570013 1.124 .869 .131 32.11 544 17,470 4780150 .241 .595 .405

146 15.41 1,839 28,335 26631339 1.646 .950 .050 25.64 1,105 28,335 16058831 1.485 .931 .069

147 13.00 1,495 19,432 14963986 2.022 .978 .022 20.56 945 19,432 9599913 2.426 .992 .008

148 21.85 58 1,267 32796 -1.417 .078 .078 32.49 39 1,267 23875 -.364 .358 .358

149 10.70 20 214 2410 .977 .836 .164 16.46 13 214 1734 1.540 .938 .062

150 11.68 99 1,156 56387 -.252 .401 .401 18.65 62 1,156 34432 -.534 .297 .297

151 13.04 538 7,017 1826189 -1.307 .096 .096 21.93 320 7,017 1076429 -1.278 .101 .101

152 23.12 342 7,906 1307264 -1.058 .145 .145 44.42 178 7,906 692257 -.374 .354 .354

153 8.99 1,611 14,486 12032370 2.168 .985 .015 14.49 1,000 14,486 7374043 0.991 .839 .161

154 14.62 731 10,685 3857233 -.577 .282 .282 26.91 397 10,685 2059966 -.993 .160 .160

155 10.83 2,036 22,051 22807732 1.253 .895 .105 16.87 1,307 22,051 14620732 .914 .820 .180

156 18.32 803 14,709 5874926 -.256 .399 .399 36.05 408 14,709 3016415 .184 .573 .427

Table 4. Summary of interoccurrence intervals for daily precipitation thresholds of 0.25 and 0.50 inch—Continued

Seq.

no.

Daily precipitation threshold of 0.25 inch and greater Daily precipitation threshold of 0.50 inch and greater

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue
Table 4 93

157 42.33 3 127 180 -.165 .434 .434 63.50 2 127 132 .096 .538 .462

158 11.51 177 2,037 167115 -1.682 .046 .046 17.71 115 2,037 102739 -2.282 .011 .011

159 12.52 1,405 17,595 12405607 .237 .594 .406 19.51 902 17,595 7961709 .173 .569 .431

160 9.65 620 5,981 1809073 -1.048 .147 .147 14.17 422 5,981 1229504 -.916 .180 .180

161 11.30 1,193 13,484 8324930 2.095 .982 .018 16.88 799 13,484 5476275 .813 .792 .208

162 11.01 892 9,819 4592341 2.517 .994 .006 18.08 543 9,819 2846195 2.730 .997 .003

163 11.24 3,064 34,426 54453267 3.113 .999 .001 18.08 1,904 34,426 34292346 3.502 1.000 0

164 9.59 54 518 13425 -.511 .305 .305 19.19 27 518 7014 .027 .511 .489

165 14.81 80 1,185 45807 -.521 .301 .301 25.21 47 1,185 29129 .546 .708 .292

166 13.82 458 6,331 1525723 1.941 .974 .026 21.68 292 6,331 948133 .762 .777 .223

167 14.04 86 1,207 50238 -.515 .303 .303 24.14 50 1,207 28574 -.650 .258 .258

168 9.32 1,512 14,097 10698467 .260 .603 .397 14.44 976 14,097 6974313 .747 .772 .228

169 10.76 113 1,216 73633 1.321 .907 .093 17.88 68 1,216 46697 1.849 .968 .032

170 14.77 412 6,084 1270904 .494 .689 .311 25.89 235 6,084 744779 1.111 .867 .133

171 14.81 556 8,233 2296632 .140 .556 .444 23.66 348 8,233 1434433 .043 .517 .483

172 10.37 3,167 32,834 52792879 1.500 .933 .067 16.18 2,029 32,834 33869040 1.309 .905 .095

173 19.39 102 1,978 99378 -.260 .397 .397 29.52 67 1,978 62938 -.711 .238 .238

174 14.11 438 6,180 1406049 1.410 .921 .079 24.05 257 6,180 822452 .990 .839 .161

175 10.69 130 1,389 90061 -.049 .480 .480 15.61 89 1,389 63691 .497 .690 .310

176 13.66 1,468 20,049 15080242 1.643 .950 .050 22.30 899 20,049 9166089 .888 .813 .187

177 14.70 2,185 32,125 35476337 .876 .809 .191 25.20 1,275 32,125 20504103 .074 .529 .471

178 12.26 27 331 3522 -1.906 .028 .028 18.39 18 331 2546 -1.068 .143 .143

179 25.88 752 19,460 7835703 3.367 1.000 0 54.36 358 19,460 3862744 3.570 1.000 0

180 8.63 1,933 16,672 16461116 1.643 .950 .050 12.68 1,315 16,672 11418088 2.614 .996 .004

181 15.78 1,790 28,238 24319273 -2.765 .003 .003 27.90 1,012 28,238 13732293 -2.145 .016 .016

182 10.60 1,314 13,932 9280165 .870 .808 .192 16.93 823 13,932 5789500 .490 .688 .312

183 10.51 184 1,934 165794 -1.602 .055 .055 15.72 123 1,934 120125 .191 .576 .424

184 8.56 101 865 46493 1.120 .869 .131 13.11 66 865 30108 .771 .779 .221

185 22.04 100 2,204 102869 -1.152 .125 .125 33.91 65 2,204 67990 -.710 .239 .239

186 16.68 137 2,285 159033 .325 .628 .373 25.39 90 2,285 98579 -.679 .249 .249

187 15.25 4 61 122 0 .500 .500 15.25 4 61 122 0 .500 .500

188 12.11 1,224 14,820 8970883 -.661 .254 .254 18.95 782 14,820 5662066 -1.108 .134 .134

189 17.84 1,481 26,415 19058114 -1.711 .044 .044 28.34 932 26,415 12012173 -1.277 .101 .101

190 9.98 1,895 18,911 18923845 4.232 1.000 0 15.03 1,258 18,911 12636160 3.828 1.000 0

191 15.94 804 12,819 5240643 .833 .798 .202 24.84 516 12,819 3383965 .912 .819 .181

192 7.76 2,341 18,176 21754381 1.888 .971 .030 11.53 1,576 18,176 14812319 2.351 .991 .009

193 17.78 684 12,164 4408850 2.709 .997 .003 29.10 418 12,164 2790783 3.462 1.000 0

194 12.81 502 6,429 1598064 -.376 .354 .354 19.08 337 6,429 1096048 .375 .646 .354

195 28.92 328 9,486 1506907 -.984 .163 .163 62.82 151 9,486 653837 -1.853 .032 .032

196 19.12 753 14,400 5290995 -1.145 .126 .126 29.75 484 14,400 3498916 .154 .561 .439

197 9.98 811 8,095 3353290 1.063 .856 .144 14.96 541 8,095 2249639 1.103 .865 .135

198 9.86 1,284 12,665 8130584 -.003 .499 .499 14.38 881 12,665 5628767 .459 .677 .323

199 7.32 3,117 22,827 36195361 1.684 .954 .046 10.98 2,079 22,827 24036260 1.024 .847 .153

200 11.37 1,242 14,121 8994755 1.571 .942 .058 18.78 752 14,121 5454295 1.295 .902 .098

201 8.90 2,577 22,939 30253920 2.074 .981 .019 13.69 1,676 22,939 19675782 1.671 .953 .047

202 11.85 41 486 11901 2.157 .985 .015 18.00 27 486 7455 1.226 .890 .110

203 10.35 1,361 14,090 9787515 1.328 .908 .092 17.40 810 14,090 5826369 1.036 .850 .150

204 6.31 220 1,388 147858 -.811 .209 .209 8.26 168 1,388 117121 .102 .541 .459

205 22.59 17 384 3588 0.709 .761 .239 42.67 9 384 2031 0.911 .819 .181

206 15.56 188 2,925 263215 -1.014 .155 .155 26.84 109 2,925 144407 -1.702 .044 .044

207 15.64 33 516 8467 -.055 .478 .478 27.16 19 516 5225 .498 .691 .309

208 16.38 503 8239 2134891 1.177 .880 .120 28.71 287 8,239 1247376 1.615 .947 .053

Table 4. Summary of interoccurrence intervals for daily precipitation thresholds of 0.25 and 0.50 inch—Continued

Seq.

no.

Daily precipitation threshold of 0.25 inch and greater Daily precipitation threshold of 0.50 inch and greater

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue
94 Atlas of Interoccurrence Intervals for Selected Thresholds of Daily Precipitation in Texas 

209 12.77 1197 15291 9205128 .350 .637 .363 19.55 782 15,291 6077305 .798 .788 .212

210 13.80 311 4292 686179 .859 .805 .195 21.35 201 4,292 435770 .252 .599 .401

211 10.57 193 2,040 178486 -2.246 .012 .012 19.07 107 2,040 100061 -1.490 .068 .068

212 14.09 1,017 14,334 7246578 -.320 .374 .374 22.75 630 14,334 4472937 -.407 .342 .342

213 10.83 293 3,173 482886 1.151 .875 .125 17.06 186 3,173 315463 1.631 .949 .051

214 15.49 75 1,162 39543 -1.388 .083 .083 24.72 47 1,162 25056 -.979 .164 .164

215 14.83 54 801 21277 -.206 .418 .418 25.84 31 801 12567 .118 .547 .453

216 14.73 103 1,517 75826 -.517 .302 .302 24.47 62 1,517 47038 .003 .501 .499

217 13.97 1,084 15,148 8277751 .469 .680 .320 22.28 680 15,148 5048432 -.894 .186 .186

218 14.82 1,248 18,497 11915399 1.979 .976 .024 26.46 699 18,497 6766738 2.140 .984 .016

219 -- -- -- -- -- -- -- -- -- -- -- -- -- --

220 13.58 1,804 24,501 21934941 -.549 .292 .292 21.82 1,123 24,501 13590117 -.705 .240 .240

221 7.09 665 4,717 1560966 -.212 .416 .416 10.06 469 4,717 1101769 -.148 .441 .441

222 17.02 1,162 19,773 12142088 3.361 1.000 0 32.52 608 19,773 6404983 2.799 .997 .003

223 14.93 436 6,509 1444920 .662 .746 .254 24.47 266 6,509 877364 .381 .648 .352

224 16.90 362 6,117 1116405 .275 .608 .392 27.93 219 6,117 670841 .039 .516 .484

225 14.65 808 11,834 5127072 3.565 1.000 0 19.86 596 11,834 3745485 2.625 .996 .004

226 13.91 2,405 33,447 39411656 -1.707 .044 .044 24.34 1,374 33,447 22385272 -1.656 .049 .049

227 8.11 148 1,200 87756 -.248 .402 .402 12.25 98 1,200 61853 .890 .813 .187

228 8.05 4,227 34,037 72418098 .753 .774 .226 11.81 2,882 34,037 49344324 .563 .713 .287

229 12.20 747 9,110 3509840 1.492 .932 .068 19.98 456 9,110 2229401 2.712 .997 .003

230 14.60 2,193 32,007 35638780 1.255 .895 .105 24.38 1,313 32,007 20654293 -1.070 .142 .142

231 10.47 3,162 33,090 52703606 .723 .765 .235 16.33 2,027 33,090 33752249 .501 .692 .308

232 9.49 263 2,497 332833 .383 .649 .351 14.86 168 2,497 207986 -.189 .425 .425

233 7.62 2,268 17,281 19824378 .959 .831 .169 11.56 1,495 17,281 13209053 1.511 .935 .065

234 8.85 117 1,035 58485 -.638 .262 .262 14.38 72 1,035 36066 -.471 .319 .319

235 10.42 2,244 23,374 26064512 -.504 .307 .307 16.43 1,423 23,374 16218554 -1.619 .053 .053

236 17.30 332 5,743 880972 -2.396 .008 .008 27.88 206 5,743 550440 -1.727 .042 .042

237 8.62 2,155 18,579 21255322 4.966 1.000 0 12.83 1,448 18,579 14493870 5.109 0 0

238 15.49 275 4,259 572595 -.639 .262 .262 22.90 186 4,259 379456 -.992 .161 .161

239 7.66 2,263 17,330 19995705 1.625 .948 .052 11.99 1,446 17,330 12967709 2.303 .989 .011

240 18.51 705 13,047 4487572 -1.115 .133 .133 34.52 378 13,047 2545358 1.085 .861 .139

241 12.48 2,998 37,406 56026179 -.077 .469 .469 19.94 1,876 37,406 34915315 -.367 .357 .357

242 9.29 1,885 17,517 16697719 .856 .804 .196 14.51 1,207 17,517 10891627 1.822 .966 .034

243 9.73 2,126 20,679 22015707 .123 .549 .451 15.39 1,344 20,679 13752995 -.655 .256 .256

244 9.20 10 92 331 -1.536 .062 .062 15.33 6 92 187 -1.368 .086 .086

245 15.83 1,667 26,383 21855729 -.433 .333 .333 26.68 989 26,383 12914604 -.550 .291 .291

246 9.03 2,219 20,030 22859786 2.337 .990 .010 13.98 1,433 20,030 15064025 3.255 .999 .001

247 11.86 2,573 30,526 39749886 1.070 .858 .142 18.40 1,659 30,526 25555968 .654 .743 .257

248 11.09 178 1,974 162767 -1.699 .045 .045 16.73 118 1,974 109881 -1.064 .144 .144

249 8.87 340 3,015 519494 .433 .667 .333 12.31 245 3,015 377854 .625 .734 .266

250 19.30 385 7,429 1378254 -1.232 .109 .109 32.44 229 7,429 811045 -1.220 .111 .111

251 34.43 7 241 699 -.785 .216 .216 60.25 4 241 249 -1.675 .047 .047

252 19.04 122 2,323 144437 .369 .644 .356 31.82 73 2,323 83645 -.200 .421 .421

253 16.09 87 1,400 64974 1.081 .860 .140 25.46 55 1,400 42136 1.213 .887 .113

254 16.70 1,167 19,485 11506633 .714 .762 .238 31.03 628 19,485 6243774 .890 .813 .187

255 7.99 2,420 19,333 23829771 1.591 .944 .056 12.46 1,552 19,333 15634068 2.873 .998 .002

256 8.62 2,113 18,213 19309818 .281 .610 .390 11.94 1,526 18,213 14020577 .604 .727 .273

257 33.78 18 608 5333 -0.187 .426 .426 86.86 7 608 1866 -0.564 .286 .286

258 17.83 1,092 19,465 10958534 1.781 .963 .037 29.85 652 19,465 6635530 2.021 .978 .022

259 12.38 365 4,519 804901 -.795 .213 .213 19.73 229 4,519 487798 -1.501 .067 .067

260 10.90 2,024 22,062 22514680 .656 .744 .256 16.63 1,327 22,062 14424841 -.919 .179 .179

Table 4. Summary of interoccurrence intervals for daily precipitation thresholds of 0.25 and 0.50 inch—Continued

Seq.

no.

Daily precipitation threshold of 0.25 inch and greater Daily precipitation threshold of 0.50 inch and greater

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue
Table 4 95

261 10.66 137 1,461 103603 .714 .762 .238 17.39 84 1,461 60290 -.277 .391 .391

262 10.49 640 6,712 2136380 -.234 .408 .408 15.12 444 6,712 1478902 -.273 .392 .392

263 30.19 614 18,538 6028718 2.546 .995 .005 62.42 297 18,538 3033956 3.048 .999 .001

264 14.37 828 11,901 5158521 2.342 .990 .010 21.76 547 11,901 3473464 2.720 .997 .003

265 13.23 1,491 19,723 15306217 2.742 .997 .003 21.00 939 19,723 9774384 2.949 .998 .002

266 7.06 469 3,310 779873 .178 .571 .429 10.15 326 3,310 548471 .518 .698 .302

267 9.55 3,813 36,415 70444872 1.571 .942 .058 14.49 2,514 36,415 46198016 .805 .790 .210

268 9.49 385 3,653 672905 -1.464 .072 .072 14.00 261 3,653 484499 .457 .676 .324

269 9.09 78 709 30293 1.462 .928 .072 14.47 49 709 19403 1.419 .922 .078

270 11.67 1,213 14154 8697852 .797 .787 .213 17.30 818 14,154 5935581 1.255 .895 .105

271 76.50 2 153 91 -.993 .161 .161 153.00 1 153 56 -.464 .321 .321

272 75.50 2 151 190 .633 .736 .264 -- -- -- -- -- -- --

273 16.28 1,952 31,770 30968826 -.096 .462 .462 26.92 1,180 31,770 18352058 -1.245 .107 .107

274 17.20 662 11,383 4045416 3.284 .999 .001 27.70 411 11,383 2492962 2.308 .990 .011

275 14.14 170 2,403 195087 -1.014 .155 .155 23.56 102 2,403 118416 -.591 .277 .277

276 16.06 402 6,457 1346587 1.304 .904 .096 27.83 232 6,457 758672 .340 .633 .367

277 9.58 117 1,121 65306 -.078 .469 .469 17.79 63 1,121 36633 .515 .697 .303

278 9.31 1,272 11,840 7591191 .500 .691 .309 14.69 806 11,840 4796101 .253 .600 .400

279 34.81 21 731 8153 .494 .689 .311 81.22 9 731 2328 -1.519 .064 .064

280 22.25 741 16,485 6115688 .062 .525 .475 42.05 392 16,485 3357536 1.342 .910 .090

281 11.09 398 4,415 913639 1.379 .916 .084 17.59 251 4,415 569567 .767 .778 .222

282 8.08 166 1,341 107735 -.715 .237 .237 14.27 94 1,341 60187 -.757 .225 .225

283 10.74 1,807 19,415 18149653 2.553 .995 .005 16.27 1,193 19,415 12000441 2.167 .985 .015

284 15.84 602 9,535 2908530 .570 .716 .284 22.92 416 9,535 2038789 .989 .839 .161

285 8.42 3,863 32,536 64066398 2.095 .982 .018 12.75 2,551 32,536 42203109 1.483 .931 .069

286 15.15 2,467 37,369 46503520 .763 .777 .223 25.77 1,450 37,369 26534571 -1.358 .087 .087

287 14.27 128 1,826 118314 .243 .596 .404 25.72 71 1,826 65374 .124 .549 .451

288 12.68 1,040 13,182 6946674 .750 .773 .227 19.50 676 13,182 4522276 .675 .750 .250

289 15.32 74 1,134 35034 -2.459 .007 .007 25.20 45 1,134 21462 -1.846 .032 .032

290 13.85 2,203 30,511 34592056 2.381 .991 .009 21.00 1,453 30,511 22381522 .641 .739 .261

291 18.02 1,083 19,511 10777060 1.143 .873 .127 28.53 684 19,511 6714568 .284 .612 .388

292 11.84 185 2,191 200440 -.259 .398 .398 19.39 113 2,191 121606 -.325 .373 .373

293 11.04 3,200 35,323 56156528 -.625 .266 .266 17.36 2,035 35,323 36246043 .663 .746 .254

294 8.51 2,214 18,834 21243119 1.540 .938 .062 12.05 1,563 18,834 14787984 .322 .626 .374

295 12.16 488 5,935 1506371 1.539 .938 .062 19.78 300 5,935 909335 .643 .740 .260

296 8.16 2,107 17,191 18654519 2.387 .992 .008 12.25 1,403 17,191 12501685 2.379 .991 .009

297 8.11 2,409 19,546 23752009 .754 .775 .225 11.91 1,641 19,546 16482400 1.947 .974 .026

298 9.77 1,047 10,227 5509865 1.633 .949 .051 15.11 677 10,227 3589342 1.660 .952 .048

299 21.18 11 233 1047 -1.051 .147 .147 38.83 6 233 651 -.291 .385 .385

300 15.87 306 4,857 719172 -.976 .165 .165 31.54 154 4,857 373323 -.038 .485 .485

301 17.52 963 16,871 8091273 -.213 .416 .416 32.44 520 16,871 4232866 -1.383 .083 .083

302 18.43 1,048 19,309 10166903 .272 .607 .393 33.64 574 19,309 5693208 1.135 .872 .128

303 8.86 55 487 13547 .148 .559 .441 12.82 38 487 9078 -.202 .420 .420

304 10.08 2,486 25,051 31890909 2.087 .982 .018 15.51 1,615 25,051 20942456 2.456 .993 .007

305 11.95 130 1,554 88994 -2.349 .009 .009 16.36 95 1,554 64054 -2.232 .013 .013

306 9.15 4,065 37,205 75864357 .358 .640 .360 14.07 2,645 37,205 49616324 .747 .772 .228

307 13.45 1,571 21,126 17004818 1.698 .955 .045 24.51 862 21,126 9276063 .954 .830 .170

308 11.26 1,578 17,772 14271550 1.224 .889 .111 15.26 1,165 17,772 10370813 .106 .542 .458

309 10.51 111 1,167 66940 0.612 .730 .270 20.12 58 1,167 35821 0.771 .780 .220

310 11.41 272 3,103 387650 -2.326 .010 .010 18.92 164 3,103 227181 -2.377 .009 .009

311 17.21 221 3,804 444356 1.471 .929 .071 31.70 120 3,804 241569 1.108 .866 .134

312 10.21 1,815 18,527 17904544 4.790 1.000 0 15.70 1,180 18,527 11676538 4.058 1.000 0

Table 4. Summary of interoccurrence intervals for daily precipitation thresholds of 0.25 and 0.50 inch—Continued

Seq.

no.

Daily precipitation threshold of 0.25 inch and greater Daily precipitation threshold of 0.50 inch and greater

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue
96 Atlas of Interoccurrence Intervals for Selected Thresholds of Daily Precipitation in Texas 

313 10.45 236 2,465 280632 -.937 .175 .175 17.24 143 2,465 160132 -1.894 .029 .029

314 11.42 99 1,131 57967 .610 .729 .271 15.93 71 1,131 41938 .650 .742 .258

315 7.47 2,502 18,684 23890242 1.915 .972 .028 10.96 1,705 18,684 16587543 2.961 .998 .002

316 18.16 109 1,979 99776 -1.355 .088 .088 34.12 58 1,979 52080 -1.221 .111 .111

317 29.58 55 1,627 38200 -1.878 .030 .030 54.23 30 1,627 22997 -.547 .292 .292

318 20.57 802 16,498 6794882 1.329 .908 .092 33.47 493 16,498 4272745 1.948 .974 .026

319 19.37 193 3,738 359344 -.092 .463 .463 31.15 120 3,738 227319 .257 .601 .399

320 28.73 279 8,016 1144627 .683 .753 .247 63.62 126 8,016 534568 1.138 .872 .128

321 9.17 2,260 20,733 23835217 1.430 .924 .076 14.20 1,460 20,733 15508273 1.632 .949 .051

322 11.23 1,117 12,538 7000532 -.016 .494 .494 15.79 794 12,538 5005672 .275 .609 .391

323 11.13 482 5,364 1291138 -.047 .481 .481 18.06 297 5,364 805645 .341 .633 .367

324 10.24 3,086 31,602 49913855 2.273 .988 .012 15.71 2,012 31,602 32593050 1.959 .975 .025

325 17.90 238 4,259 463955 -2.260 .012 .012 31.78 134 4,259 272048 -.935 .175 .175

326 7.85 827 6,492 2716380 .593 .723 .277 11.37 571 6,492 1849086 -.098 .461 .461

327 14.36 566 8,126 2331885 .578 .718 .282 21.79 373 8,126 1559090 .962 .832 .168

328 15.98 61 975 28624 -.507 .306 .306 19.90 49 975 22877 -.513 .304 .304

329 7.08 1,633 11,566 9790226 2.569 .995 .005 10.62 1,089 11,566 6408367 1.005 .842 .158

330 8.17 4,473 36,526 81530137 -.227 .410 .410 12.18 2,998 36,526 54520210 -.402 .344 .344

331 15.02 446 6,698 1530198 .895 .815 .185 25.57 262 6,698 879359 .061 .525 .475

332 15.78 2,020 31,881 33078104 2.123 .983 .017 25.16 1,267 31,881 20459487 .802 .789 .211

333 9.86 2,175 21,436 23827747 1.788 .963 .037 14.49 1,479 21,436 16454041 2.530 .994 .006

334 15.97 967 15,442 7535360 .499 .691 .309 30.76 502 15,442 4004272 1.285 .901 .099

335 17.14 1,296 22,219 14053461 -1.492 .068 .068 31.70 701 22,219 7653079 -.793 .214 .214

336 13.44 154 2,070 169887 1.416 .922 .078 21.34 97 2,070 109373 1.526 .936 .064

337 13.27 830 11,010 4611456 .462 .678 .322 21.38 515 11,010 2783001 -.722 .235 .235

338 13.22 437 5777 1293163 .886 .812 .188 20.41 283 5,777 837542 .716 .763 .237

339 7.65 635 4859 1527663 -.426 .335 .335 10.70 454 4,859 1104506 .051 .520 .480

340 10.07 620 6,240 1936424 .045 .518 .482 15.88 393 6,240 1248021 .612 .730 .270

341 22.33 436 9,737 2150958 .482 .685 .315 39.10 249 9,737 1267738 1.251 .894 .106

342 24.41 168 4,100 343152 -.081 .468 .468 36.61 112 4,100 242512 1.031 .849 .151

343 11.00 1,155 12,702 7296651 -.311 .378 .378 17.40 730 12,702 4655674 .196 .578 .422

344 10.90 3,159 34,428 56399287 3.617 1.000 0 17.28 1,992 34,428 36023699 3.908 1.000 0

345 8.98 54 485 12699 -.385 .350 .350 13.11 37 485 8529 -.521 .301 .301

346 16.89 1,275 21,528 13357158 -1.654 .049 .049 31.20 690 21,528 7284134 -.876 .191 .191

347 13.86 86 1,192 47690 -1.118 .132 .132 25.36 47 1,192 26228 -.756 .225 .225

348 14.03 796 11,166 4451641 .083 .533 .467 23.41 477 11,166 2651007 -.172 .432 .432

349 14.44 773 11,161 4237151 -.855 .196 .196 23.60 473 11,161 2514629 -1.783 .037 .037

350 12.86 2,191 28,183 31341778 1.227 .890 .110 20.32 1,387 28,183 19583217 .126 .550 .450

351 14.53 266 3,865 519250 .286 .613 .387 25.60 151 3,865 296976 .377 .647 .353

352 28.70 37 1,062 16823 -1.514 .065 .065 37.93 28 1,062 14033 -.515 .303 .303

353 9.44 345 3,257 586564 1.416 .922 .078 14.35 227 3,257 381446 .831 .797 .203

354 9.81 701 6,876 2482902 1.387 .917 .083 15.63 440 6,876 1557536 1.076 .859 .141

355 10.89 1,026 11,170 5739368 .089 .535 .465 16.95 659 11,170 3635833 -.540 .295 .295

356 18.58 1,926 35,793 34512162 .096 .538 .462 30.18 1,186 35,793 21094432 -.368 .357 .357

357 12.10 2,611 31,587 41456184 .471 .681 .319 19.27 1,639 31,587 26028401 .387 .651 .349

358 14.06 1,343 18,884 12765506 .425 .665 .335 22.45 841 18,884 8054260 .718 .764 .236

359 14.70 151 2,220 168619 .128 .551 .449 21.77 102 2,220 118941 .884 .812 .188

360 21.29 34 724 11069 -1.017 .155 .155 40.22 18 724 5854 -.747 .228 .228

361 16.67 9 150 861 1.432 .924 .076 30.00 5 150 481 1.095 .863 .137

362 10.04 2,114 21,229 22288882 -.533 .297 .297 14.71 1,443 21,229 14971118 -1.485 .069 .069

363 9.16 239 2,188 266243 .489 .688 .312 13.94 157 2,188 167215 -.574 .283 .283

364 9.12 1,051 9,588 4988820 -.554 .290 .290 14.27 672 9,588 3145664 -1.058 .145 .145

Table 4. Summary of interoccurrence intervals for daily precipitation thresholds of 0.25 and 0.50 inch—Continued

Seq.

no.

Daily precipitation threshold of 0.25 inch and greater Daily precipitation threshold of 0.50 inch and greater

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue
Table 4 97

365 8.61 2,588 22,280 28484266 -1.058 .145 .145 12.83 1,737 22,280 19229782 -.449 .327 .327

366 10.22 247 2,525 318428 .575 .717 .283 12.02 210 2,525 272092 .660 .745 .255

367 9.39 1,229 11,543 7269443 1.509 .934 .066 14.03 823 11,543 4870065 1.257 .896 .104

368 17.59 479 8,426 1952752 -1.226 .110 .110 30.64 275 8,426 1141458 -.424 .336 .336

369 41.00 3 123 35 -2.431 .008 .008 123.00 1 123 16 -1.281 .100 .100

370 22.16 295 6,537 919864 -1.368 .086 .086 51.47 127 6,537 350418 -3.042 .001 .001

371 34.35 574 19,719 5880126 1.619 .947 .053 88.43 223 19,719 2343437 1.703 .956 .044

372 15.57 524 8,156 2173902 .687 .754 .246 25.57 319 8,156 1315367 .345 .635 .365

373 10.94 17 186 1261 -1.446 .074 .074 20.67 9 186 769 -.422 .336 .336

374 17.14 51 874 24361 1.151 .875 .125 33.62 26 874 12955 1.238 .892 .108

375 16.00 670 10,721 3778272 2.331 .990 .010 27.21 394 10,721 2261195 2.428 .992 .008

376 15.56 187 2,910 271790 -.026 .490 .490 24.45 119 2,910 179476 .691 .755 .245

377 11.71 1,550 18,150 14566657 2.426 .992 .008 18.32 991 18,150 9378306 2.334 .990 .010

378 10.14 1,434 14,540 10454094 .182 .572 .428 15.50 938 14,540 6813217 -.047 .481 .481

379 12.07 15 181 1416 .289 .614 .386 20.11 9 181 997 1.164 .878 .122

380 11.24 127 1,428 101436 2.316 .990 .010 17.85 80 1,428 63170 1.641 .950 .050

381 8.88 2,140 18,998 20553700 .890 .813 .187 12.98 1,464 18,998 14326320 2.001 .977 .023

382 8.00 37 296 5671 .375 .646 .354 12.87 23 296 3856 1.103 .865 .135

383 17.11 1,897 32,450 30487091 -.715 .237 .237 26.38 1,230 32,450 20361509 1.232 .891 .109

384 16.30 501 8,168 2158917 2.138 .984 .016 28.76 284 8,168 1228570 1.729 .958 .042

385 9.39 1,835 17,222 15941324 .658 .745 .255 15.00 1,148 17,222 9731783 -.912 .181 .181

386 30.50 8 244 872 -.522 .301 .301 34.86 7 244 765 -.478 .317 .317

387 11.63 179 2,081 185381 -.108 .457 .457 18.42 113 2,081 120945 .528 .701 .299

388 10.86 227 2,464 270600 -.846 .199 .199 16.43 150 2,464 177840 -.799 .212 .212

389 13.44 27 363 5969 1.962 .975 .025 19.11 19 363 4192 1.628 .948 .052

390 7.05 2,479 17,476 21842703 .721 .765 .235 10.20 1,713 17,476 15096863 .616 .731 .269

391 11.17 1,430 15,972 11894180 2.720 .997 .003 17.12 933 15,972 7634932 1.307 .904 .096

392 21.10 49 1,034 16942 -4.016 0 0 25.85 40 1,034 13640 -3.729 0 0

393 39.98 265 10,594 1486970 1.673 .953 .047 99.94 106 10,594 609899 1.538 .938 .062

394 15.50 2 31 32 .079 .532 .468 31.00 1 31 18 .279 .610 .390

395 12.93 705 9,115 3385753 2.472 .993 .007 18.99 480 9,115 2267227 1.381 .916 .084

396 9.23 2,135 19,696 21466366 1.678 .953 .047 13.85 1,422 19,696 14450754 2.084 .981 .019

397 17.87 797 14,241 5346285 -2.833 .002 .002 29.55 482 14,241 3295911 -1.509 .066 .066

398 14.93 2,266 33,819 38609764 .630 .736 .264 25.03 1,351 33,819 23265907 1.174 .880 .120

399 12.77 1,536 19,618 15011129 -.250 .401 .401 20.14 974 19,618 9643923 .509 .695 .305

400 8.94 2,156 19,271 20985378 .818 .793 .207 13.25 1,455 19,271 14186277 .785 .784 .216

401 14.93 387 5,779 1001316 -3.563 0 0 26.27 220 5,779 574317 -2.480 .007 .007

402 22.09 11 243 1733 1.704 .956 .044 40.50 6 243 844 .669 .748 .252

403 11.39 1,188 13,535 7919555 -.893 .186 .186 15.17 892 13,535 5776183 -2.232 .013 .013

404 9.55 2,158 20,610 22808633 2.064 .980 .020 14.38 1,433 20,610 15185945 1.860 .969 .031

405 14.37 827 11,884 5147927 2.371 .991 .009 24.11 493 11,884 3059698 1.711 .956 .044

406 10.36 2,094 21,685 23097048 1.371 .915 .085 15.93 1,361 21,685 15125631 1.598 .945 .055

407 9.76 380 3,708 688879 -.750 .227 .227 15.26 243 3,708 444554 -.358 .360 .360

408 10.06 3,395 34,142 58397246 .768 .779 .221 15.75 2,168 34,142 37569426 1.219 .889 .111

409 22.52 54 1,216 32268 -.219 .413 .413 39.23 31 1,216 19514 .341 .633 .367

410 8.62 1,670 14,398 12056647 .202 .580 .420 13.03 1,105 14,398 7946613 -.060 .476 .476

411 14.36 1,333 19,141 12853297 .475 .683 .317 23.87 802 19,141 7741022 .419 .662 .338

412 10.10 1,376 13,897 9236735 -2.180 .015 .015 15.37 904 13,897 6340552 .490 .688 .312

413 12.78 2,361 30,162 35588632 -0.042 .483 .483 19.77 1,526 30,162 23069517 0.164 .565 .435

414 12.45 275 3,423 478361 .470 .681 .319 19.45 176 3,423 318336 1.305 .904 .096

415 15.48 1,388 21,490 15184263 1.169 .879 .121 26.96 797 21,490 8566001 .013 .505 .495

416 16.17 1,197 19,352 12027313 2.303 .989 .011 28.46 680 19,352 6816001 1.622 .948 .052

Table 4. Summary of interoccurrence intervals for daily precipitation thresholds of 0.25 and 0.50 inch—Continued

Seq.

no.

Daily precipitation threshold of 0.25 inch and greater Daily precipitation threshold of 0.50 inch and greater

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue
98 Atlas of Interoccurrence Intervals for Selected Thresholds of Daily Precipitation in Texas 

417 13.19 233 3,072 375973 1.336 .909 .091 19.82 155 3,072 232518 -.504 .307 .307

418 13.81 1,805 24,925 23841631 4.406 1.000 0 23.60 1,056 24,925 14017937 3.668 1.000 0

419 10.50 2,159 22,658 24671563 .698 .757 .243 16.25 1,394 22,658 15887321 .388 .651 .349

420 17.29 1,107 19,138 10672993 .436 .668 .332 28.95 661 19,138 6222695 -.721 .236 .236

421 17.48 1,784 31,191 27171844 -1.711 .044 .044 35.57 877 31,191 13494886 -.684 .247 .247

422 29.27 396 11,589 2175910 -1.783 .037 .037 62.64 185 11,589 920297 -3.334 0 0

423 18.79 617 11,596 3636802 .715 .763 .237 29.89 388 11,596 2280190 .464 .679 .321

424 53.25 4 213 498 .586 .721 .279 106.50 2 213 351 1.587 .944 .056

425 22.81 932 21,262 9890793 -.092 .463 .463 43.84 485 21,262 5282135 .933 .825 .176

426 20.14 887 17,867 8120879 1.282 .900 .100 39.53 452 17,867 4039683 .016 .506 .494

427 -- -- -- -- -- -- -- -- -- -- -- -- -- --

428 11.82 406 4,798 999657 .920 .821 .179 17.45 275 4,798 681681 .956 .830 .170

429 10.10 536 5,412 1506439 1.549 .939 .061 16.20 334 5,412 952313 1.699 .955 .045

430 10.48 851 8,915 3929166 1.809 .965 .035 16.70 534 8,915 2404796 .412 .660 .340

431 9.96 387 3,856 770605 1.117 .868 .132 14.95 258 3,856 527759 1.697 .955 .045

432 8.57 1,014 8,688 4424642 .248 .598 .402 12.65 687 8,688 3043215 .896 .815 .185

433 16.20 1,689 27,354 23018610 -.252 .400 .400 24.27 1,127 27,354 15500535 .327 .628 .372

434 9.55 1,424 13,597 9826989 .985 .838 .162 14.27 953 13,597 6686347 1.711 .956 .044

435 9.39 110 1,033 61344 1.448 .926 .074 12.60 82 1,033 44218 .691 .755 .245

436 12.48 2,329 29,054 34412914 1.432 .924 .076 19.93 1,458 29,054 21598437 1.305 .904 .096

437 8.55 2,963 25,322 38503534 2.486 .994 .006 12.54 2,020 25,322 26344411 2.341 .990 .010

438 16.10 1,160 18,671 11147389 1.733 .958 .042 23.72 787 18,671 7614564 1.769 .962 .038

439 17.12 477 8,164 1893842 -1.035 .150 .150 24.52 333 8,164 1356391 -.068 .473 .473

440 15.53 599 9,302 2911216 1.906 .972 .028 25.21 369 9,302 1778971 1.217 .888 .112

441 17.44 1,361 23,733 16905797 2.989 .999 .001 33.19 715 23,733 8950746 2.545 .995 .005

442 9.13 1,398 12,769 9101489 1.277 .899 .101 13.96 915 12,769 6060333 1.960 .975 .025

443 10.71 1,213 12,987 7973601 .743 .771 .229 16.05 809 12,987 5224169 -.273 .393 .393

444 15.08 107 1,613 91053 .988 .838 .162 26.44 61 1,613 51566 .652 .743 .257

445 17.56 1,090 19,140 10824708 2.157 .984 .016 29.58 647 19,140 6541581 2.489 .994 .006

446 12.66 93 1,177 50218 -1.377 .084 .084 24.02 49 1,177 26193 -1.112 .133 .133

447 16.87 1,360 22,938 15848681 1.027 .848 .152 28.35 809 22,938 9341907 .337 .632 .368

448 10.30 3,060 31,527 48053495 -.363 .358 .358 16.09 1,960 31,527 30777384 -.296 .384 .384

449 8.97 593 5,317 1546958 -.790 .215 .215 13.16 404 5,317 1056752 -.560 .288 .288

450 9.38 2,190 20,533 23109920 2.258 .988 .012 14.58 1,408 20,533 15049280 2.671 .996 .004

451 9.84 565 5,562 1586922 .410 .659 .341 15.16 367 5,562 1001204 -.632 .264 .264

452 19.00 16 304 2505 .208 .582 .418 27.64 11 304 1994 1.106 .866 .134

453 20.22 104 2,103 111403 .331 .630 .370 45.72 46 2,103 47412 -.232 .408 .408

454 17.67 1,799 31,784 27641700 -2.436 .007 .007 30.71 1,035 31,784 15899152 -1.860 .031 .031

455 16.74 53 887 18391 -2.744 .003 .003 32.85 27 887 10541 -1.077 .141 .141

456 67.00 1 67 61 1.422 .922 .078 67.00 1 67 61 1.422 .922 .078

457 11.00 31 341 6693 2.568 .995 .005 16.24 21 341 4719 2.524 .994 .006

458 7.77 801 6,223 2440748 -1.014 .155 .155 11.27 552 6,223 1734169 .394 .653 .347

459 14.19 79 1,121 43296 -.342 .366 .366 18.68 60 1,121 32171 -.582 .280 .280

460 11.01 2,974 32,732 50324874 3.207 .999 .001 16.60 1,972 32,732 32682337 .974 .835 .165

461 13.62 2,260 30,785 34915510 .304 .619 .381 22.37 1,376 30,785 21254757 .227 .590 .410

462 10.76 1,649 17,740 15018092 1.882 .970 .030 17.22 1,030 17,740 9360977 1.368 .914 .086

463 9.86 758 7,477 2908149 1.251 .895 .105 15.61 479 7,477 1816422 .544 .707 .293

464 9.68 2,324 22,500 26536141 1.249 .894 .106 15.17 1,483 22,500 17141085 1.828 .966 .034

465 10.51 187 1,966 168406 -1.986 .024 .024 14.78 133 1,966 118440 -1.879 .030 .030

466 8.23 3,186 26,233 42908445 2.619 .996 .004 12.32 2,129 26,233 28449166 1.500 .933 .067

467 22.30 496 11,063 3191857 6.302 0 0 41.43 267 11,063 1733019 4.908 1.000 0

468 10.79 92 993 38814 -2.497 .006 .006 14.60 68 993 26980 -2.869 .002 .002

Table 4. Summary of interoccurrence intervals for daily precipitation thresholds of 0.25 and 0.50 inch—Continued

Seq.

no.

Daily precipitation threshold of 0.25 inch and greater Daily precipitation threshold of 0.50 inch and greater

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue
Table 4 99

469 8.04 1,221 9,821 6169438 1.754 .960 .040 12.10 812 9,821 3967303 -.248 .402 .402

470 15.17 6 91 196 -1.197 .116 .116 18.20 5 91 147 -1.370 .085 .085

471 10.35 1,293 13,388 8751613 .693 .756 .244 16.84 795 13,388 5331388 .089 .535 .465

472 8.85 381 3,372 648835 .341 .633 .367 12.09 279 3,372 473126 .168 .567 .433

473 11.58 1,660 19,226 16341290 1.697 .955 .045 17.59 1,093 19,226 11030325 2.852 .998 .002

474 12.28 2,050 25,176 26160634 1.080 .860 .140 19.53 1,289 25,176 16385967 .613 .730 .270

475 11.06 2,891 31,959 47377798 2.381 .991 .009 17.68 1,808 31,959 30157112 3.228 .999 .001

476 11.50 1,586 18,237 14514468 .251 .599 .401 16.13 1,131 18,237 10731690 2.365 .991 .009

477 12.14 346 4,201 743014 .720 .764 .236 20.20 208 4,201 457896 1.200 .885 .115

478 11.08 2,082 23,063 24662052 2.151 .984 .016 17.17 1,343 23,063 16047375 2.298 .989 .011

479 10.42 172 1,792 146439 -1.131 .129 .129 14.57 123 1,792 105732 -.780 .218 .218

480 12.55 453 5,684 1318533 .891 .813 .187 19.33 294 5,684 890513 1.954 .975 .025

481 8.23 1,538 12,650 9637568 -.630 .264 .264 12.53 1,010 12,650 6400313 .104 .541 .459

482 10.60 350 3,709 634842 -.711 .239 .239 16.34 227 3,709 406600 -.891 .187 .187

483 9.56 332 3,174 551943 1.501 .933 .067 14.49 219 3,174 366970 1.432 .924 .076

484 10.94 250 2,736 330297 -.937 .174 .174 18.87 145 2,736 199000 .067 .527 .473

485 15.42 55 848 21393 -1.061 .144 .144 22.92 37 848 12997 -1.807 .035 .035

486 11.59 3,001 34,779 53134982 1.726 .958 .042 18.49 1,881 34,779 33323900 1.411 .921 .079

487 11.32 926 10,484 4782043 -.782 .217 .217 17.62 595 10,484 3015634 -1.400 .081 .081

488 24.40 1,153 28,138 16165351 -.204 .419 .419 44.59 631 28,138 8805519 -.353 .362 .362

489 10.25 1,134 11,627 6583550 -.079 .468 .468 15.99 727 11,627 4327476 1.117 .868 .132

490 10.47 745 7,802 3003158 1.577 .943 .057 16.32 478 7,802 1922421 1.173 .879 .121

491 8.66 1,475 12,770 9913831 3.503 1.000 0 13.14 972 12,770 6422892 1.885 .970 .030

492 10.65 2,355 25,088 30287564 2.124 .983 .017 16.58 1,513 25,088 19786524 2.866 .998 .002

493 9.06 3,938 35,661 72414439 3.402 1.000 0 13.71 2,602 35,661 47765696 2.610 .995 .005

494 8.99 474 4,263 1067186 2.122 .983 .017 13.80 309 4,263 690973 1.495 .933 .067

495 7.58 2,683 20,344 29257933 6.464 0 0 11.17 1,821 20,344 19880366 5.415 0 0

496 15.70 1,373 21,557 14906539 .467 .680 .320 27.92 772 21,557 8333320 .071 .528 .472

497 31.35 26 815 11044 .374 .646 .354 101.88 8 815 3938 1.019 .846 .154

498 9.71 1,963 19,069 19204355 2.001 .977 .023 14.85 1,284 19,069 12802880 2.842 .998 .002

499 14.35 1,237 17,748 11363175 2.142 .984 .016 23.14 767 17,748 6988378 1.283 .900 .100

500 11.56 100 1,156 58406 .182 .572 .428 20.28 57 1,156 31937 -.401 .344 .344

501 14.48 353 5,112 904377 .076 .530 .470 19.44 263 5,112 671451 -.033 .487 .487

502 8.58 3,563 30,570 55416516 1.815 .965 .035 12.64 2,418 30,570 37850618 2.054 .980 .020

503 17.69 346 6,120 1019994 -1.180 .119 .119 29.71 206 6,120 604269 -1.029 .152 .152

504 20.58 179 3,683 303773 -1.818 .035 .035 36.47 101 3,683 184115 -.176 .430 .430

505 14.47 74 1,071 35475 -1.561 .059 .059 23.28 46 1,071 20699 -1.876 .030 .030

506 9.83 3,804 37,401 71908857 1.160 .877 .123 15.55 2,406 37,401 45846536 1.611 .946 .054

507 7.89 177 1,396 136691 2.452 .993 .007 10.66 131 1,396 101798 2.246 .988 .012

508 12.49 1,272 15,882 10179558 .481 .685 .315 19.20 827 15,882 6603455 .275 .608 .392

509 14.79 1,726 25,519 22482975 1.503 .934 .066 23.94 1,066 25,519 13714334 .469 .680 .320

510 16.02 131 2,098 137216 -.029 .488 .488 25.28 83 2,098 79246 -1.418 .078 .078

511 8.03 2,315 18,591 21426495 -.359 .360 .360 12.04 1,544 18,591 14959989 2.882 .998 .002

512 14.04 2,246 31,532 35114112 -.687 .246 .246 23.02 1,370 31,532 21491225 -.321 .374 .374

513 13.14 1,622 21,306 17814535 2.161 .985 .015 21.26 1,002 21,306 11104865 2.212 .987 .014

514 19.00 2 38 67 1.869 .969 .031 -- -- -- -- -- -- --

515 17.22 934 16,084 7465990 -.319 .375 .375 30.29 531 16,084 4137639 -1.240 .108 .108

516 20.84 132 2,751 172123 -1.035 .150 .150 39.30 70 2,751 92656 -.546 .293 .293

517 16.56 1,181 19,560 11616014 0.339 .633 .367 31.35 624 19,560 6251553 1.055 .854 .146

518 13.47 2,723 36,688 50120983 .308 .621 .379 23.06 1,591 36,688 28647651 -1.273 .102 .102

519 14.75 523 7,716 1982657 -.689 .246 .246 23.45 329 7,716 1243286 -.643 .260 .260

520 12.41 54 670 18932 .592 .723 .277 19.71 34 670 11836 .396 .654 .346

Table 4. Summary of interoccurrence intervals for daily precipitation thresholds of 0.25 and 0.50 inch—Continued

Seq.

no.

Daily precipitation threshold of 0.25 inch and greater Daily precipitation threshold of 0.50 inch and greater

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue
100 Atlas of Interoccurrence Intervals for Selected Thresholds of Daily Precipitation in Texas 

521 9.09 1,960 17,822 17705303 1.053 .854 .146 13.06 1,365 17,822 12283966 .634 .737 .263

522 13.86 534 7,402 1983048 .136 .554 .446 20.62 359 7,402 1430139 2.507 .994 .006

523 13.99 272 3,804 556905 2.184 .986 .014 22.38 170 3,804 353442 2.102 .982 .018

524 25.37 96 2,435 107801 -1.318 .094 .094 51.81 47 2,435 60003 .577 .718 .282

525 -- -- -- -- -- -- -- -- -- -- -- -- -- --

526 16.14 2,018 32,561 33480753 1.484 .931 .069 26.93 1,209 32,561 20253162 1.744 .959 .041

527 7.34 1,185 8,692 5193629 .505 .693 .307 10.55 824 8,692 3669381 1.226 .890 .110

528 7.26 435 3,157 692247 .295 .616 .384 9.90 319 3,157 517444 .854 .803 .197

529 9.68 1,197 11,583 7258866 2.822 .998 .002 14.09 822 11,583 5038446 2.898 .998 .002

530 8.24 4,140 34,124 72401913 2.785 .997 .003 11.82 2,886 34,124 50625973 2.617 .996 .004

531 12.07 527 6,363 1698358 .515 .697 .303 17.11 372 6,363 1237139 1.514 .935 .065

532 11.38 3,168 36,056 57706945 1.014 .845 .155 17.83 2,022 36,056 37256561 1.718 .957 .043

533 16.91 1,523 25,757 19523054 -.313 .377 .377 31.30 823 25,757 10455840 -.671 .251 .251

534 15.41 64 986 29246 -1.013 .156 .156 29.00 34 986 17340 .348 .636 .364

535 10.63 3,946 41,954 84085122 1.722 .957 .043 16.62 2,525 41,954 52551805 -.682 .248 .248

536 11.62 13 151 926 -.353 .362 .362 16.78 9 151 481 -1.518 .065 .065

537 10.95 2,910 31,864 47388318 2.068 .981 .019 17.43 1,828 31,864 29614929 1.249 .894 .106

538 19.57 117 2,290 133900 -.009 .496 .496 32.25 71 2,290 79754 -.277 .391 .391

539 13.62 1,448 19,726 14455306 .802 .789 .211 22.60 873 19,726 8758190 .878 .810 .190

540 11.49 145 1,666 131448 1.841 .967 .033 17.35 96 1,666 92989 2.763 .997 .003

541 10.09 3,471 35,035 61969705 1.958 .975 .025 15.45 2,267 35,035 40166817 .944 .827 .173

542 21.53 55 1,184 24949 -3.003 .001 .001 29.60 40 1,184 19400 -1.980 .024 .024

543 16.68 502 8,373 2110672 .167 .566 .434 28.19 297 8,373 1261587 .437 .669 .331

544 13.04 2,250 29,330 33132548 .339 .633 .367 21.13 1,388 29,330 20016145 -1.074 .141 .141

545 13.27 633 8,397 2597309 -.989 .161 .161 22.16 379 8,397 1547786 -.921 .179 .179

546 8.26 3,802 31,403 60793115 1.961 .975 .025 12.32 2,549 31,403 41015073 2.167 .985 .015

547 13.60 1,298 17,650 11483862 .158 .563 .437 21.66 815 17,650 7119349 -.502 .308 .308

548 7.59 1,727 13,112 11416490 .599 .725 .275 11.54 1,136 13,112 7583955 1.069 .857 .143

549 29.30 30 879 13096 -.064 .474 .474 73.25 12 879 5427 .174 .569 .431

550 10.48 80 838 33012 -.235 .407 .407 16.76 50 838 23224 1.329 .908 .092

551 10.10 543 5,486 1573600 2.280 .989 .011 15.95 344 5,486 982543 1.326 .908 .092

552 8.73 2,242 19,567 22923883 3.699 1.000 0 13.49 1,451 19,567 15039497 3.921 1.000 0

553 10.86 14 152 1143 .481 .685 .315 16.89 9 152 763 .600 .726 .274

554 8.19 1,454 11,901 8717772 .502 .692 .308 12.33 965 11,901 5789067 .439 .670 .330

555 7.74 19 147 1357 -.214 .415 .415 14.70 10 147 748 .097 .539 .461

556 7.87 2,541 19,994 26322771 3.164 .999 .001 11.62 1,721 19,994 17943899 3.087 .999 .001

557 7.83 35 274 4816 .045 .518 .482 10.54 26 274 3722 .397 .654 .346

558 10.44 204 2,129 209291 -.896 .185 .185 15.21 140 2,129 149309 .038 .515 .485

559 8.72 67 584 20341 .563 .713 .287 14.60 40 584 11669 -.010 .496 .496

560 7.87 31 244 4263 1.227 .890 .110 12.20 20 244 2746 .971 .834 .166

561 7.76 2,293 17,792 20974668 2.343 .990 .010 11.74 1,515 17,792 13898292 2.105 .982 .018

562 8.04 2,574 20,691 27172240 1.792 .963 .037 12.07 1,715 20,691 18263324 2.105 .982 .018

563 8.12 2,081 16,893 18259683 3.068 .999 .001 12.33 1,370 16,893 12544699 5.391 0 0

564 8.34 2,277 18,979 22675167 4.084 1.000 0 12.70 1,494 18,979 15009491 3.930 1.000 0

565 7.99 613 4,897 1538862 1.084 .861 .139 11.21 437 4,897 1097849 .943 .827 .173

566 7.96 1,881 14,981 14155922 .353 .638 .362 12.03 1,245 14,981 9528127 1.327 .908 .092

567 12.31 714 8,792 3604488 6.868 0 0 20.12 437 8,792 2315732 7.439 0 0

568 7.86 2,011 15,815 16356093 2.218 .987 .013 11.87 1,332 15,815 10883214 2.103 .982 .018

569 8.92 1,034 9,218 4734852 -0.361 .359 .359 13.74 671 9,218 3123490 0.448 .673 .327

570 7.36 494 3,637 896195 -.092 .463 .463 10.19 357 3,637 654609 .272 .607 .393

571 8.44 2,148 18,133 20157093 2.812 .998 .002 12.39 1,463 18,133 14068822 4.018 1.000 0

572 11.28 1,132 12,769 7319074 .740 .770 .230 17.59 726 12,769 4584988 -.505 .307 .307

Table 4. Summary of interoccurrence intervals for daily precipitation thresholds of 0.25 and 0.50 inch—Continued

Seq.

no.

Daily precipitation threshold of 0.25 inch and greater Daily precipitation threshold of 0.50 inch and greater

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue
Table 4 101

573 18.88 267 5,041 680425 .313 .623 .377 30.74 164 5,041 412263 -.059 .476 .476

574 7.88 1,417 11,163 7908486 -.004 .498 .498 12.20 915 11,163 5122146 .155 .561 .439

575 15.33 1,142 17,501 9644311 -2.043 .021 .021 21.88 800 17,501 6745228 -1.786 .037 .037

576 12.10 299 3,617 565895 1.393 .918 .082 18.94 191 3,617 356700 .781 .783 .217

577 12.65 1,468 18,568 14210735 2.833 .998 .002 19.59 948 18,568 9166233 2.212 .987 .014

578 8.15 2,471 20,145 25480011 2.044 .980 .020 12.38 1,627 20,145 17089852 2.992 .999 .001

579 10.13 1,391 14,090 10012296 1.402 .920 .080 16.56 851 14,090 6258105 2.215 .987 .013

580 9.13 8 73 311 .319 .625 .375 14.60 5 73 166 -.350 .363 .363

581 7.31 324 2,368 367557 -1.305 .096 .096 10.67 222 2,368 254592 -.811 .209 .209

582 12.33 1,500 18,495 14363857 2.382 .991 .009 18.82 983 18,495 9335727 1.466 .929 .071

583 27.76 583 16,182 5022639 2.709 .997 .003 47.59 340 16,182 3004255 2.941 .998 .002

584 7.87 31 244 3632 -.383 .351 .351 13.56 18 244 2059 -.458 .323 .323

585 12.43 1,056 13,130 7141614 1.697 .955 .045 20.78 632 13,130 4241719 .972 .834 .166

586 137.33 3 412 430 -.913 .181 .181 412.00 1 412 134 -.605 .273 .273

587 12.46 293 3,651 526810 -.447 .328 .328 18.07 202 3,651 367173 -.105 .458 .458

588 12.50 684 8,550 2822231 -1.578 .057 .057 19.30 443 8,550 1811480 -1.585 .056 .056

589 8.94 733 6,553 2494131 1.805 .964 .036 14.12 464 6,553 1597483 1.894 .971 .029

590 7.87 47 370 10041 1.838 .967 .033 9.49 39 370 8680 2.196 .986 .014

591 8.80 415 3,653 756512 -.069 .472 .472 12.73 287 3,653 530267 .339 .633 .367

592 11.24 1,965 22,076 21991164 1.067 .857 .143 17.93 1,231 22,076 13896575 1.381 .916 .084

593 8.46 1,834 15,514 14865018 3.330 1.000 0 12.22 1,270 15,514 10293157 2.768 .997 .003

594 8.40 699 5,874 2099416 1.036 .850 .150 12.58 467 5,874 1397359 .704 .759 .241

595 13.35 691 9,226 3278753 1.302 .904 .096 20.83 443 9,226 2121698 1.394 .918 .082

596 10.36 2,481 25,710 32642538 2.027 .979 .021 15.73 1,634 25,710 21341320 1.121 .869 .131

597 7.37 2,790 20,570 29279299 1.862 .969 .031 10.62 1,937 20,570 20205043 1.083 .861 .139

598 7.27 144 1,047 63500 -3.277 .001 .001 9.79 107 1,047 47902 -2.595 .005 .005

599 13.96 1,268 17,699 11653646 2.377 .991 .009 23.23 762 17,699 6850632 .761 .777 .223

600 10.69 1,828 19,532 18694523 3.494 1.000 0 16.13 1,211 19,532 12258748 2.202 .986 .014

601 7.69 4,201 32,319 68413511 .872 .808 .192 11.74 2,754 32,319 44708109 .418 .662 .338

602 9.51 1,617 15,379 12760182 1.828 .966 .034 14.44 1,065 15,379 8198492 .063 .525 .475

603 8.78 709 6,226 2237301 .631 .736 .264 13.00 479 6,226 1545404 1.380 .916 .084

604 10.59 1,159 12,277 7233532 .986 .838 .162 16.39 749 12,277 4719067 1.251 .894 .106

605 14.38 432 6,210 1390111 1.308 .905 .095 26.09 238 6,210 772566 1.214 .888 .112

606 16.10 327 5,266 864802 .139 .555 .445 28.01 188 5,266 497825 .135 .554 .446

607 15.96 244 3,895 485185 .569 .715 .285 26.50 147 3,895 284847 -.105 .458 .458

608 14.28 1,482 21,162 16229354 2.332 .990 .010 22.71 932 21,162 10022899 .866 .807 .193

609 30.16 96 2,895 122987 -1.951 .026 .026 53.61 54 2,895 65426 -2.074 .019 .019

610 13.88 2,196 30,487 32201726 -3.087 .001 .001 22.09 1,380 30,487 20048750 -3.020 .001 .001

611 15.60 527 8,219 2237260 1.314 .905 .095 26.09 315 8,219 1347095 1.249 .894 .106

612 16.56 218 3,610 400975 .487 .687 .313 25.97 139 3,610 266504 1.270 .898 .102

613 15.66 44 689 14407 -.569 .285 .285 18.62 37 689 11492 -1.037 .150 .150

614 18.13 185 3,354 295403 -1.127 .130 .130 27.27 123 3,354 181777 -2.281 .011 .011

615 15.25 4 61 134 .341 .633 .367 30.50 2 61 64 .121 .548 .452

616 15.02 125 1,878 115647 -.285 .388 .388 21.10 89 1,878 86879 .647 .741 .259

617 8.01 219 1,753 167927 -3.208 .001 .001 11.17 157 1,753 119512 -2.854 .002 .002

618 7.78 2,655 20,642 28108673 2.301 .989 .011 11.44 1,804 20,642 19410677 3.128 .999 .001

619 12.04 2,363 28,443 32780271 -2.067 .019 .019 19.10 1,489 28,443 20715344 -1.453 .073 .073

620 13.67 51 697 19798 1.409 .921 .079 19.36 36 697 14817 1.881 .970 .030

621 9.21 1,791 16,498 15445910 3.334 1.000 0 14.65 1,126 16,498 9832430 3.404 1.000 0

622 9.25 3,914 36,185 69576118 -1.894 .029 .029 13.73 2,635 36,185 47297473 -.702 .242 .242

623 11.28 653 7,364 2442168 .696 .757 .243 18.09 407 7,364 1520463 .510 .695 .305

624 9.97 195 1,944 177131 -1.584 .057 .057 14.62 133 1,944 119828 -1.460 .072 .072

Table 4. Summary of interoccurrence intervals for daily precipitation thresholds of 0.25 and 0.50 inch—Continued

Seq.

no.

Daily precipitation threshold of 0.25 inch and greater Daily precipitation threshold of 0.50 inch and greater

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue
102 Atlas of Interoccurrence Intervals for Selected Thresholds of Daily Precipitation in Texas 

625 12.27 812 9,960 4320862 3.382 1.000 0 19.04 523 9,960 2798800 2.954 .998 .002

626 10.90 993 10,827 5371124 -.046 .482 .482 16.14 671 10,827 3610622 -.270 .394 .394

627 22.78 519 11,821 3283419 2.777 .997 .003 48.25 245 11,821 1571694 2.314 .990 .010

628 19.32 259 5,003 577015 -3.049 .001 .001 40.35 124 5,003 244218 -4.102 0 0

629 12.24 2,162 26,452 28651776 .161 .564 .436 20.36 1,299 26,452 17046237 -.488 .313 .313

630 11.58 857 9,923 4188069 -.762 .223 .223 19.05 521 9,923 2607778 .349 .637 .363

631 11.57 942 10,894 5333907 2.101 .982 .018 18.13 601 10,894 3292484 .244 .597 .403

632 10.23 778 7,960 3160297 .996 .840 .160 15.98 498 7,960 2013579 .615 .731 .269

633 9.62 177 1,702 145379 -.803 .211 .211 14.42 118 1,702 100420 0 .500 .500

634 13.81 21 290 2960 -.222 .412 .412 24.17 12 290 1737 -.010 .496 .496

635 14.20 1,891 26,842 26037914 1.955 .975 .025 21.75 1,234 26,842 16626291 .238 .594 .406

636 7.11 2,919 20,742 30075203 -.611 .271 .271 10.78 1,924 20,742 20288204 1.273 .898 .102

637 17.35 1,407 24,410 17999159 3.128 .999 .001 27.93 874 24,410 11138424 2.262 .988 .012

638 14.18 784 11,115 4441487 .940 .826 .174 23.25 478 11,115 2783608 1.812 .965 .035

639 10.55 495 5,224 1335987 1.283 .900 .100 16.22 322 5,224 879698 1.428 .923 .077

640 7.11 825 5,865 2510236 1.870 .969 .031 10.64 551 5,865 1699225 2.099 .982 .018

641 15.95 75 1196 42419 -.813 .208 .208 27.18 44 1,196 25589 -.316 .376 .376

642 12.70 23 292 3488 .322 .626 .374 24.33 12 292 2056 1.041 .851 .149

643 9.72 3,381 32,853 57107517 2.846 .998 .002 15.37 2,138 32,853 36469162 3.077 .999 .001

644 20.27 122 2,473 157866 .889 .813 .187 32.54 76 2,473 102185 1.319 .906 .094

645 17.03 1,611 27,442 22140552 .113 .545 .455 28.26 971 27,442 13636277 1.269 .898 .102

646 34.18 606 20,715 6381510 .712 .762 .238 71.43 290 20,715 3153559 1.472 .929 .071

647 11.93 76 907 38421 1.733 .958 .042 19.30 47 907 23996 1.494 .932 .068

648 15.18 126 1,913 106277 -2.298 .011 .011 22.24 86 1,913 79537 -.532 .298 .298

649 25.77 317 8,170 1204469 -2.155 .016 .016 51.38 159 8,170 592696 -1.911 .028 .028

650 12.99 1,108 14,391 7901356 -.515 .303 .303 21.13 681 14,391 4870792 -.271 .393 .393

651 18.08 155 2,802 221681 .449 .673 .327 36.39 77 2,802 106419 -.205 .419 .419

652 15.96 50 798 20353 .247 .598 .402 21.00 38 798 15800 .449 .673 .327

653 10.72 101 1,083 56501 .576 .718 .282 14.84 73 1,083 42423 1.083 .861 .139

654 16.67 621 10,351 3335884 1.637 .949 .051 27.31 379 10,351 2066760 1.809 .965 .035

655 12.12 236 2,861 328043 -.753 .226 .226 18.58 154 2,861 207730 -1.226 .110 .110

656 8.37 567 4,743 1337837 -.209 .417 .417 12.72 373 4,743 881982 -.098 .461 .461

657 13.21 878 11,595 5142292 .525 .700 .300 22.56 514 11,595 3053714 .973 .835 .165

658 13.84 414 5,729 1240742 1.630 .948 .052 21.70 264 5,729 765671 .351 .637 .363

659 11.33 245 2,776 325068 -1.195 .116 .116 17.91 155 2,776 205365 -.980 .164 .164

660 8.64 556 4,805 1373717 1.160 .877 .123 12.92 372 4,805 932412 1.446 .926 .074

661 8.48 334 2,832 488256 1.025 .847 .153 12.37 229 2,832 328209 .319 .625 .375

662 12.86 427 5,490 1193062 .640 .739 .261 19.96 275 5,490 802324 1.805 .964 .036

663 17.89 1,824 32,622 29713720 -.093 .463 .463 31.25 1,044 32,622 17283379 .837 .799 .201

664 11.59 3,199 37,084 60706657 2.297 .989 .011 18.49 2,006 37,084 37691502 1.035 .850 .150

665 23.24 810 18,826 7357442 -1.727 .042 .042 38.19 493 18,826 4590034 -.419 .338 .338

666 25.98 50 1,299 34859 .899 .816 .184 44.79 29 1,299 21270 1.206 .886 .114

667 18.04 759 13,689 5024482 -1.566 .059 .059 27.99 489 13,689 3147495 -2.283 .011 .011

668 23.81 326 7,761 1279152 .349 .636 .364 40.42 192 7,761 764813 .636 .738 .262

669 7.93 716 5,676 2054598 .515 .697 .303 11.68 486 5,676 1414802 .984 .837 .163

670 13.51 628 8,485 2644110 -.329 .371 .371 22.39 379 8,485 1555000 -1.110 .134 .134

671 9.40 1,999 18,797 19574729 3.244 .999 .001 14.37 1,308 18,797 12823168 2.700 .997 .003

672 13.75 1,407 19,344 13795246 .892 .814 .186 21.74 890 19,344 8808878 1.205 .886 .114

673 14.77 371 5,481 1051344 1.136 .872 .128 23.42 234 5,481 672696 1.298 .903 .097

674 13.24 135 1,788 120869 .030 .512 .488 16.71 107 1,788 91380 -.801 .212 .212

675 13.66 194 2,649 257025 .007 .503 .497 22.64 117 2,649 152050 -.353 .362 .362

676 11.87 280 3,324 404840 -3.769 0 0 17.68 188 3,324 274136 -2.913 .002 .002

Table 4. Summary of interoccurrence intervals for daily precipitation thresholds of 0.25 and 0.50 inch—Continued

Seq.

no.

Daily precipitation threshold of 0.25 inch and greater Daily precipitation threshold of 0.50 inch and greater

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue
Table 4 103

677 17.68 1,162 20,545 11890990 -.226 .411 .411 30.94 664 20,545 6746562 -.487 .313 .313

678 9.24 17 157 1566 1.239 .892 .108 17.44 9 157 668 -.283 .388 .388

679 16.66 1,358 22,630 15509607 .598 .725 .275 30.50 742 22,630 8413495 .100 .540 .460

680 11.75 371 4,360 821875 .540 .705 .295 18.24 239 4,360 534728 .705 .759 .241

681 10.22 82 838 34578 .100 .540 .460 12.32 68 838 27244 -.626 .266 .266

682 11.57 440 5,092 1114366 -.191 .424 .424 18.58 274 5,092 702254 .191 .576 .424

683 9.71 1,257 12,199 7731544 .516 .697 .303 14.79 825 12,199 5177722 1.440 .925 .075

684 10.21 1,520 15,522 12223894 2.445 .993 .007 16.07 966 15,522 7774115 1.989 .977 .023

685 7.42 4,746 35,218 85682145 3.012 .999 .001 11.27 3,126 35,218 56907194 3.275 .999 .001

686 11.67 501 5,847 1542610 2.063 .980 .020 17.61 332 5,847 1031623 1.984 .976 .024

687 14.20 109 1,548 82549 -.390 .348 .348 18.88 82 1,548 61498 -.487 .313 .313

688 10.06 446 4,487 1037105 1.335 .909 .091 13.64 329 4,487 740111 .085 .534 .466

689 9.44 625 5,899 1857185 .323 .627 .373 14.35 411 5,899 1266709 1.578 .943 .057

690 8.37 1,496 12,527 9118300 -1.801 .036 .036 12.67 989 12,527 6056181 -1.217 .112 .112

691 7.61 2,408 18,319 22469042 1.591 .944 .056 11.02 1,663 18,319 15926971 3.222 .999 .001

692 11.97 1,570 18,792 14378022 -1.739 .041 .041 17.85 1,053 18,792 10097126 1.154 .876 .124

693 14.41 1,330 19,163 13263315 2.577 .995 .005 26.04 736 19,163 7339138 1.913 .972 .028

694 10.36 705 7,301 2610731 .664 .746 .254 15.67 466 7,301 1765630 1.418 .922 .078

695 18.04 750 13,531 5028803 -.424 .336 .336 32.61 415 13,531 2723525 -1.058 .145 .145

696 16.50 777 12,822 4980127 -.012 .495 .495 30.53 420 12,822 2709040 .217 .586 .414

697 7.71 3,060 23,585 36567957 1.282 .900 .100 11.59 2,035 23,585 24813108 2.655 .996 .004

698 12.90 2,908 37,526 56767236 3.774 1.000 0 21.04 1,784 37,526 34744242 2.778 .997 .003

699 11.47 138 1,583 116511 1.357 .913 .087 18.20 87 1,583 73277 1.036 .850 .150

700 11.11 1,770 19,662 18163120 3.192 .999 .001 17.13 1,148 19,662 12101346 4.240 1.000 0

701 10.36 173 1,793 148825 -.921 .179 .179 14.70 122 1,793 110188 .143 .557 .443

702 17.07 71 1,212 35911 -2.413 .008 .008 28.86 42 1,212 20119 -2.352 .009 .009

703 12.11 390 4,722 933701 .480 .684 .316 17.75 266 4,722 647835 .891 .813 .187

704 16.96 25 424 4862 -.716 .237 .237 28.27 15 424 2692 -1.029 .152 .152

705 8.76 1,466 12,843 9773286 2.532 .994 .006 13.49 952 12,843 6283918 1.492 .932 .068

706 7.92 4,533 35,879 82786121 2.103 .982 .018 11.63 3,085 35,879 56634010 2.244 .988 .012

707 7.74 1,202 9,308 5710706 1.252 .895 .105 11.19 832 9,308 4051330 2.312 .990 .010

708 19.38 834 16,163 7022583 2.097 .982 .018 34.03 475 16,163 3950141 1.096 .863 .137

709 14.75 4 59 175 1.673 .953 .047 -- -- -- -- -- -- --

710 16.64 72 1,198 39297 -1.306 .096 .096 29.95 40 1,198 23196 -.349 .363 .363

711 16.49 899 14,820 6860903 1.554 .940 .060 26.37 562 14,820 4391562 2.240 .987 .013

712 19.16 70 1,341 47606 .207 .582 .418 30.48 44 1,341 27044 -.957 .169 .169

713 8.48 1,197 10,153 6306833 2.271 .988 .012 12.55 809 10,153 4277612 2.048 .980 .020

714 26.07 14 365 1609 -2.400 .008 .008 45.63 8 365 690 -2.584 .005 .005

715 17.38 84 1,460 63055 .449 .673 .327 29.20 50 1,460 34446 -.689 .245 .245

716 18.80 336 6,316 1098780 1.128 .870 .130 35.29 179 6,316 557320 -.326 .372 .372

717 16.92 1,959 33,144 32161943 -.715 .238 .238 31.66 1,047 33,144 17136494 -.693 .244 .244

718 7.62 904 6,885 3089589 -.375 .354 .354 10.54 653 6,885 2235437 -.246 .403 .403

719 7.51 581 4,364 1223720 -1.450 .074 .074 10.42 419 4,364 871348 -1.664 .048 .048

720 8.10 4,105 33,230 69121389 1.492 .932 .068 12.45 2,669 33,230 43994009 -.709 .239 .239

721 10.74 3,395 36,455 62710938 1.351 .912 .088 17.09 2,133 36,455 39951396 2.206 .986 .014

722 10.35 156 1,614 139425 2.326 .990 .010 14.67 110 1,614 94089 1.089 .862 .138

723 6.76 333 2,252 377866 .245 .597 .403 9.97 226 2,252 256790 .237 .594 .406

724 12.82 714 9,151 3371494 1.482 .931 .069 20.61 444 9,151 2103332 1.290 .901 .099

725 13.82 663 9,162 3072791 0.523 .699 .301 21.76 421 9,162 2027135 1.816 .965 .035

726 10.31 113 1,165 64994 -.232 .408 .408 18.20 64 1,165 37508 .085 .534 .466

727 8.58 2,945 25,281 37543483 .801 .788 .212 13.15 1,923 25,281 24406359 .308 .621 .379

728 8.30 1,242 10,305 6716997 3.029 .999 .001 12.37 833 10,305 4568859 3.224 .999 .001

Table 4. Summary of interoccurrence intervals for daily precipitation thresholds of 0.25 and 0.50 inch—Continued

Seq.

no.

Daily precipitation threshold of 0.25 inch and greater Daily precipitation threshold of 0.50 inch and greater

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue
104 Atlas of Interoccurrence Intervals for Selected Thresholds of Daily Precipitation in Texas 

729 11.88 543 6,453 1780479 .656 .744 .256 18.70 345 6,453 1168833 1.610 .946 .054

730 13.00 1 13 6 -.133 .447 .447 13.00 1 13 6 -.133 .447 .447

731 11.35 551 6,252 1736723 .338 .632 .368 15.40 406 6,252 1243900 -.695 .244 .244

732 12.82 532 6,819 1731496 -1.814 .035 .035 21.51 317 6,819 1045734 -1.001 .159 .159

733 26.46 13 344 2529 .818 .793 .207 49.14 7 344 1576 1.416 .922 .078

734 20.55 1,122 23,057 12166769 -3.446 0 0 37.13 621 23,057 6699801 -2.770 .003 .003

735 15.11 131 1,979 115843 -2.108 .018 .018 29.10 68 1,979 56863 -2.213 .013 .013

736 13.06 620 8,096 2625192 1.984 .976 .024 20.44 396 8,096 1701881 2.126 .983 .017

737 25.45 104 2,647 147077 1.211 .887 .113 54.02 49 2,647 71429 1.230 .891 .109

738 19.34 741 14,333 5390606 .712 .762 .238 39.93 359 14,333 2699143 1.612 .947 .054

739 22.46 222 4,987 524243 -1.367 .086 .086 44.53 112 4,987 238069 -2.704 .003 .003

740 17.29 56 968 28830 .825 .795 .205 33.38 29 968 12768 -.843 .200 .200

741 15.78 9 142 542 -.789 .215 .215 20.29 7 142 508 .101 .540 .460

742 9.75 2,714 26,466 36179510 .666 .747 .253 15.32 1,728 26,466 23481431 1.936 .974 .026

743 7.78 4,294 33,395 72672082 1.540 .938 .062 11.39 2,933 33,395 49936576 1.844 .967 .033

744 14.07 450 6,333 1450179 .651 .742 .258 24.74 256 6,333 827032 .561 .713 .287

745 11.64 769 8,954 3531808 1.242 .893 .107 17.66 507 8,954 2334324 1.108 .866 .134

746 12.93 1,590 20,552 17079797 3.132 .999 .001 20.68 994 20,552 10909280 3.715 1.000 0

747 14.97 1,307 19,569 13256751 2.294 .989 .011 26.59 736 19,569 7517058 2.060 .980 .020

748 10.38 3,173 32,946 53894649 3.035 .999 .001 15.48 2,128 32,946 35139584 .194 .577 .423

749 11.88 1,143 13,573 7201561 -4.193 0 0 18.62 729 13,573 4500147 -4.227 0 0

750 7.79 2,386 18,579 21988371 -.673 .250 .250 11.20 1,659 18,579 15608768 .904 .817 .183

751 10.06 758 7,628 2853514 -.619 .268 .268 15.57 490 7,628 1864812 -.083 .467 .467

752 29.66 41 1,216 24753 -.078 .469 .469 71.53 17 1,216 10686 .242 .596 .404

753 10.64 191 2,033 203039 1.096 .863 .137 15.17 134 2,033 144632 1.240 .892 .108

754 7.62 338 2,575 394465 -2.979 .001 .001 11.34 227 2,575 272494 -1.765 .039 .039

755 17.67 1,217 21,499 13113325 .144 .557 .443 30.03 716 21,499 7708194 .070 .528 .472

756 64.00 1 64 17 -.812 .209 .209 64.00 1 64 17 -.812 .209 .209

757 16.65 351 5,844 1073596 1.518 .935 .065 27.06 216 5,844 647874 .674 .750 .250

758 9.56 3,383 32,344 56229822 2.799 .997 .003 14.52 2,228 32,344 36764242 1.663 .952 .048

759 12.68 1,214 15,392 9587696 1.581 .943 .057 21.90 703 15,392 5686612 2.346 .991 .010

760 17.20 1,241 21,345 13487352 1.119 .868 .132 29.24 730 21,345 8016377 1.354 .912 .088

761 16.48 821 13,531 5586561 .287 .613 .387 28.43 476 13,531 3188238 -.377 .353 .353

762 23.88 1,059 25,291 13454526 .265 .604 .396 42.87 590 25,291 7427365 -.189 .425 .425

763 14.44 82 1,184 40681 -2.541 .006 .006 17.94 66 1,184 34204 -1.753 .040 .040

764 10.70 3,065 32,783 51093162 1.629 .948 .052 16.57 1,979 32,783 32938154 1.186 .882 .118

765 11.16 1,093 12,195 6661742 -.024 .490 .490 18.12 673 12,195 4139086 .388 .651 .349

766 10.83 247 2,674 302537 -2.284 .011 .011 15.82 169 2,674 196673 -2.918 .002 .002

767 14.39 2,307 33,202 38401907 .225 .589 .411 24.43 1,359 33,202 22235774 -.920 .179 .179

768 14.66 2,314 33,925 39465593 .455 .675 .325 23.96 1,416 33,925 24112633 .254 .600 .400

769 16.94 125 2,118 116863 -2.269 .012 .012 24.92 85 2,118 81269 -1.552 .060 .060

770 34.92 233 8,136 987103 1.095 .863 .137 67.80 120 8,136 518077 1.163 .877 .123

771 16.51 225 3,714 416763 -.066 .474 .474 26.34 141 3,714 261722 -.009 .496 .496

772 14.08 13 183 1038 -.795 .213 .213 16.64 11 183 874 -.756 .225 .225

773 18.46 28 517 6506 -.927 .177 .177 30.41 17 517 3871 -.851 .198 .198

774 15.37 2,008 30,870 30764239 -.574 .283 .283 25.51 1,210 30,870 18744183 .219 .587 .413

775 13.82 22 304 3567 .542 .706 .294 19.00 16 304 2752 .912 .819 .181

776 10.71 655 7,015 2306910 .183 .573 .427 15.18 462 7,015 1698062 1.783 .963 .037

777 11.75 583 6,852 1890077 -2.246 .012 .012 16.92 405 6,852 1383772 -0.094 .462 .462

778 16.41 594 9,749 2648854 -3.595 0 0 31.96 305 9,749 1287111 -4.061 0 0

779 16.55 967 16,007 8169378 2.993 .999 .001 27.65 579 16,007 5051786 3.757 1.000 0

780 9.63 3,588 34,558 63614594 2.707 .997 .003 14.41 2,399 34,558 43390285 3.966 1.000 0

Table 4. Summary of interoccurrence intervals for daily precipitation thresholds of 0.25 and 0.50 inch—Continued

Seq.

no.

Daily precipitation threshold of 0.25 inch and greater Daily precipitation threshold of 0.50 inch and greater

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue
Table 4 105

781 13.70 2,526 34,614 43558220 -.317 .376 .376 23.91 1,448 34,614 24587111 -1.245 .107 .107

782 8.01 1,161 9,303 5512121 1.221 .889 .111 11.84 786 9,303 3775776 1.590 .944 .056

783 18.48 79 1,460 47073 -2.829 .002 .002 27.04 54 1,460 30596 -2.849 .002 .002

784 21.17 223 4,721 463590 -3.086 .001 .001 33.96 139 4,721 304665 -1.459 .072 .072

785 22.06 865 19,079 8291989 .249 .598 .402 38.31 498 19,079 4963990 1.736 .959 .041

786 22.96 851 19,541 8431539 .710 .761 .239 41.84 467 19,541 4616387 .439 .670 .330

787 10.28 589 6,055 1796182 .306 .620 .380 15.73 385 6,055 1113046 -1.532 .063 .063

788 9.77 165 1,612 135479 .416 .661 .339 13.11 123 1,612 99943 .156 .562 .438

789 7.68 1,086 8,344 4567668 .465 .679 .321 15.25 547 8,344 2317346 .626 .734 .266

790 8.34 266 2,219 288738 -.612 .270 .270 11.21 198 2,219 219103 -.064 .474 .474

791 13.87 340 4,714 817584 .646 .741 .259 19.48 242 4,714 587683 .817 .793 .207

792 9.38 48 450 12908 2.342 .990 .010 14.52 31 450 8805 2.530 .994 .006

793 9.06 2,117 19,181 20683287 1.492 .932 .068 13.42 1,429 19,181 13771465 .318 .625 .375

794 8.00 1,461 11,685 8385367 -1.168 .122 .122 12.06 969 11,685 5496814 -1.567 .059 .059

795 11.27 1,513 17,047 13271699 1.963 .975 .025 17.76 960 17,047 8510813 2.153 .984 .016

796 21.59 242 5,225 683575 2.189 .986 .014 35.30 148 5,225 410148 1.281 .900 .100

797 17.15 1,659 28,459 24123107 1.543 .939 .061 29.77 956 28,459 13690375 .342 .634 .366

798 22.39 31 694 9177 -1.417 .078 .078 33.05 21 694 5203 -2.270 .012 .012

799 13.21 693 9,155 3098339 -1.062 .144 .144 22.77 402 9,155 1861866 .410 .659 .341

800 14.72 78 1,148 43092 -.574 .283 .283 24.96 46 1,148 27348 .420 .663 .337

801 24.97 593 14,804 4391299 .018 .507 .493 44.46 333 14,804 2547303 1.057 .855 .145

802 33.60 45 1,512 26597 -2.535 .006 .006 63.00 24 1,512 12697 -2.547 .005 .005

803 11.20 652 7,299 2368251 -.209 .417 .417 17.67 413 7,299 1527963 .484 .686 .314

804 17.46 39 681 13270 -.008 .497 .497 30.96 22 681 6328 -1.261 .104 .104

805 13.83 831 11,493 4682039 -.976 .165 .165 23.46 490 11,493 2721514 -1.284 .100 .100

806 8.25 2,079 17,161 18431372 2.623 .996 .004 12.38 1,386 17,161 12426870 2.897 .998 .002

807 9.82 1,337 13,131 8882903 .756 .775 .225 14.87 883 13,131 5978638 1.610 .946 .054

808 11.63 1,549 18,012 14488661 2.631 .996 .004 17.14 1,051 18,012 9507767 .252 .599 .401

809 16.41 1,124 18,442 10536323 .963 .832 .168 28.37 650 18,442 6024707 .229 .591 .409

810 17.65 1,165 20,566 12363645 1.895 .971 .029 33.88 607 20,566 6289618 .327 .628 .372

811 7.85 940 7,376 3421642 -.691 .245 .245 11.49 642 7,376 2389328 .401 .656 .344

812 13.64 490 6,684 1697586 1.405 .920 .080 21.42 312 6,684 1119934 2.266 .988 .012

813 7.55 11 83 363 -1.177 .120 .120 10.38 8 83 299 -.487 .313 .313

814 14.86 1,642 24,404 20213620 .623 .733 .267 30.02 813 24,404 9981111 .303 .619 .381

815 8.08 3,758 30,377 56887715 -.355 .361 .361 11.93 2,547 30,377 39292002 1.371 .915 .085

816 7.91 1,634 12,922 10490376 -.444 .329 .329 11.71 1,104 12,922 7175938 .347 .636 .364

817 11.19 556 6,220 1764796 .842 .800 .200 16.33 381 6,220 1188525 .103 .541 .459

818 10.07 1,969 19,833 19987355 1.818 .965 .035 16.02 1,238 19,833 12568946 1.451 .927 .073

819 17.30 1,668 28,862 24137436 .196 .578 .422 32.18 897 28,862 12651426 -1.175 .120 .120

820 14.37 62 891 25869 -.865 .194 .194 26.21 34 891 15984 .558 .712 .288

821 18.51 430 7,961 1656600 -1.154 .124 .124 32.49 245 7,961 989750 .404 .657 .343

822 12.18 1,564 19,050 15617716 3.314 1.000 0 19.54 975 19,050 9802072 3.000 .999 .001

823 13.33 2,442 32,540 40553747 1.772 .962 .038 22.14 1,470 32,540 23941714 .069 .528 .473

824 12.86 165 2,122 172976 -.266 .395 .395 19.83 107 2,122 107286 -.985 .162 .162

825 19.35 209 4,045 436011 .788 .785 .215 24.22 167 4,045 366942 1.934 .973 .027

826 7.85 3,375 26,503 44659745 -.144 .443 .443 12.02 2,205 26,503 29063716 -.434 .332 .332

827 7.70 1,356 10,437 7164375 .794 .786 .214 11.74 889 10,437 4753343 1.270 .898 .102

828 8.22 3,143 25,827 41751582 2.786 .997 .003 11.89 2,173 25,827 28870398 2.329 .990 .010

829 7.46 724 5,401 1934058 -0.503 .307 .307 10.89 496 5,401 1320077 -0.558 .289 .289

830 13.38 979 13,102 6557874 1.221 .889 .111 20.83 629 13,102 4211155 .955 .830 .170

831 9.97 1,422 14,176 10321498 1.571 .942 .058 15.28 928 14,176 6828810 2.015 .978 .022

832 11.02 159 1,752 133388 -.925 .178 .178 18.44 95 1,752 76173 -1.430 .076 .076

Table 4. Summary of interoccurrence intervals for daily precipitation thresholds of 0.25 and 0.50 inch—Continued

Seq.

no.

Daily precipitation threshold of 0.25 inch and greater Daily precipitation threshold of 0.50 inch and greater

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue
106 Atlas of Interoccurrence Intervals for Selected Thresholds of Daily Precipitation in Texas 

833 16.25 101 1,641 73756 -1.915 .028 .028 28.29 58 1,641 45228 -.654 .256 .256

834 14.88 276 4,106 598385 1.613 .947 .053 25.82 159 4,106 333420 .468 .680 .320

835 8.09 2,293 18,549 20916812 -1.364 .086 .086 11.64 1,594 18,549 14690273 -.436 .331 .331

836 12.54 602 7,548 2363795 1.718 .957 .043 21.08 358 7,548 1381553 .739 .770 .230

837 7.41 1,612 11,942 9807974 1.320 .907 .093 11.07 1,079 11,942 6573995 1.159 .877 .123

838 7.88 967 7,618 3607585 -1.107 .134 .134 11.15 683 7,618 2614725 .229 .591 .409

839 7.71 292 2,252 318877 -.893 .186 .186 12.11 186 2,252 206319 -.352 .363 .363

840 11.23 3,248 36,458 60493334 2.143 .984 .016 17.49 2,084 36,458 39588209 3.328 1.000 0

841 7.97 2,267 18,077 20703004 .856 .804 .196 12.02 1,504 18,077 13927583 1.649 .950 .050

842 8.91 2,102 18,731 19859384 .698 .757 .243 13.55 1,382 18,731 13287530 1.713 .957 .043

843 8.83 407 3,594 714364 -.813 .208 .208 12.93 278 3,594 506798 .418 .662 .338

844 11.16 1,573 17,555 14055769 1.238 .892 .108 15.83 1,109 17,555 9564235 -1.007 .157 .157

845 7.00 534 3,740 1028112 1.184 .882 .118 10.28 364 3,740 714229 1.629 .948 .052

846 7.29 889 6,477 2865087 -.250 .401 .401 10.48 618 6,477 2027481 .561 .713 .287

847 11.50 1,560 17,934 14728493 3.619 1.000 0 16.79 1,068 17,934 9787314 1.245 .893 .107

848 11.33 2,538 28,763 37346894 2.024 .979 .021 17.72 1,623 28,763 24595059 3.749 1.000 0

849 8.69 781 6,785 2683056 .612 .730 .270 14.28 475 6,785 1608472 -.070 .472 .472

850 13.13 109 1,431 72872 -1.187 .118 .118 21.36 67 1,431 44284 -1.081 .140 .140

851 9.61 38 365 8833 2.922 .998 .002 13.04 28 365 6362 2.246 .988 .012

852 7.75 59 457 13495 .013 .505 .495 9.52 48 457 11207 .262 .603 .397

853 7.83 35 274 4771 -.051 .480 .480 11.91 23 274 3105 -.121 .452 .452

854 14.94 1,265 18,899 12231394 1.432 .924 .076 26.92 702 18,899 7003549 2.560 .995 .005

855 10.30 541 5,570 1529326 .605 .727 .273 15.78 353 5,570 1001131 .597 .725 .275

856 14.96 1,251 18,709 11922655 1.153 .875 .125 26.54 705 18,709 6721120 .880 .811 .190

857 13.62 668 9,100 3263071 3.294 1.000 0 21.36 426 9,100 2153782 3.974 1.000 0

858 14.05 753 10,580 4034916 .615 .731 .269 21.95 482 10,580 2631850 1.224 .889 .111

859 15.01 624 9,367 2915686 -.101 .460 .460 24.59 381 9,367 1785434 .019 .508 .492

860 18.16 67 1,217 34389 -2.219 .013 .013 34.77 35 1,217 17885 -1.642 .050 .050

861 14.35 1,007 14,445 7093445 -1.357 .087 .087 24.48 590 14,445 4109211 -1.501 .067 .067

862 8.23 927 7,632 3622130 1.263 .897 .103 12.25 623 7,632 2469582 1.677 .953 .047

863 7.61 56 426 13001 1.166 .878 .122 12.17 35 426 8933 2.032 .979 .021

864 23.47 770 18,069 6972385 .109 .544 .456 39.45 458 18,069 4144913 .064 .525 .475

865 18.59 126 2,342 136594 -1.443 .075 .075 30.42 77 2,342 88086 -.351 .363 .363

866 18.26 149 2,721 206874 .434 .668 .332 29.90 91 2,721 126808 .401 .656 .344

867 12.24 1,299 15,899 10710520 2.322 .990 .010 20.00 795 15,899 6696488 2.910 .998 .002

868 12.46 1,746 21,746 19292227 1.174 .880 .120 20.29 1,072 21,746 11932335 1.345 .911 .089

869 16.87 1,093 18,440 9867273 -1.194 .116 .116 30.84 598 18,440 5294697 -1.681 .046 .046

870 7.43 212 1,575 176650 1.465 .929 .071 11.01 143 1,575 119420 1.252 .895 .105

871 18.00 14 252 2306 1.991 .977 .023 42.00 6 252 922 .932 .824 .176

872 13.50 36 486 8156 -.703 .241 .241 19.44 25 486 5592 -.689 .246 .246

873 7.16 3,276 23,470 38508162 .166 .566 .434 10.48 2,240 23,470 26287375 .003 .501 .499

874 6.68 857 5,724 2381869 -1.465 .071 .071 9.52 601 5,724 1651141 -1.701 .044 .044

875 7.46 65 485 14511 -1.109 .134 .134 12.76 38 485 8388 -.958 .169 .169

876 -- -- -- -- -- -- -- -- -- -- -- -- -- --

877 17.92 24 430 5846 1.128 .870 .130 26.88 16 430 4212 1.555 .940 .060

878 7.98 1,963 15,666 15422098 .229 .591 .409 11.85 1,322 15,666 10245044 -.670 .251 .251

879 18.10 1,022 18,493 9575937 .738 .770 .230 30.12 614 18,493 5776263 .748 .773 .227

880 24.78 9 223 815 -.976 .165 .165 74.33 3 223 205 -1.161 .123 .123

881 14.70 1,265 18,595 12312471 2.887 .998 .002 24.47 760 18,595 7293773 1.539 .938 .062

882 13.33 137 1,826 115307 -1.584 .057 .057 20.75 88 1,826 73956 -1.292 .098 .098

883 13.21 825 10,901 4378824 -1.304 .096 .096 21.98 496 10,901 2652567 -.726 .234 .234

884 14.36 949 13,631 6288924 -1.477 .070 .070 24.87 548 13,631 3588815 -1.586 .056 .056

Table 4. Summary of interoccurrence intervals for daily precipitation thresholds of 0.25 and 0.50 inch—Continued

Seq.

no.

Daily precipitation threshold of 0.25 inch and greater Daily precipitation threshold of 0.50 inch and greater

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue
Table 4 107

885 14.10 2,106 29,698 31604706 .846 .801 .199 22.67 1,310 29,698 19556709 .337 .632 .368

886 9.68 2,208 21,366 23807526 .757 .775 .225 15.03 1,422 21,366 15399429 .895 .815 .185

887 8.71 2,880 25,079 37365560 3.222 .999 .001 13.17 1,904 25,079 24686379 2.568 .995 .005

888 10.86 1,743 18,929 17145077 2.843 .998 .002 16.95 1,117 18,929 11033462 2.528 .994 .006

889 13.94 985 13,726 6902184 1.143 .873 .127 26.70 514 13,726 3655942 1.429 .923 .077

890 14.62 895 13,085 5747203 -.959 .169 .169 24.97 524 13,085 3288918 -1.612 .054 .054

891 21.60 840 18,143 8049984 2.832 .998 .002 34.10 532 18,143 4887440 .508 .694 .306

892 19.85 364 7,226 1313486 -.041 .483 .483 32.70 221 7,226 784469 -.452 .326 .326

893 14.47 1,862 26,939 25415334 .999 .841 .159 24.94 1,080 26,939 14237163 -1.213 .113 .113

894 11.42 493 5,631 1356094 -.885 .188 .188 17.22 327 5,631 912394 -.282 .389 .389

895 21.53 793 17,071 6853565 .612 .730 .270 43.55 392 17,071 3533534 1.923 .973 .027

896 8.39 4,261 35,755 78040924 2.768 .997 .003 12.59 2,840 35,755 52245719 2.679 .996 .004

897 14.15 13 184 1192 -.021 .492 .492 20.44 9 184 811 -.107 .457 .457

898 6.92 175 1,211 107083 .242 .596 .404 9.24 131 1,211 79355 .009 .503 .497

899 19.33 3 58 70 -.586 .279 .279 29.00 2 58 44 -.591 .277 .277

900 11.01 139 1,531 106744 .065 .526 .474 17.01 90 1,531 68162 -.175 .431 .431

901 15.56 2,189 34,050 37854078 1.275 .899 .101 24.34 1,399 34,050 24451383 1.723 .958 .042

902 16.78 67 1,124 39728 .781 .783 .218 22.04 51 1,124 30605 .839 .799 .201

903 28.72 880 25,276 11203495 .379 .648 .352 56.04 451 25,276 5754618 .354 .638 .362

904 39.60 10 396 2049 .191 .576 .424 79.20 5 396 1434 1.737 .959 .041

905 24.52 678 16,626 5825750 1.517 .935 .065 47.37 351 16,626 2962410 .495 .690 .310

906 14.82 2,135 31,631 33644608 -.288 .387 .387 25.76 1,228 31,631 19308874 -.352 .362 .362

907 -- -- -- -- -- -- -- -- -- -- -- -- -- --

908 14.38 1,376 19,782 13856245 1.162 .877 .123 27.10 730 19,782 7526596 1.984 .976 .024

909 13.85 606 8,392 2571356 .479 .684 .316 23.91 351 8,392 1463351 -.208 .418 .418

910 27.68 256 7,085 888482 -.562 .287 .287 56.23 126 7,085 440254 -.266 .395 .395

911 25.27 83 2,097 88867 .334 .631 .369 58.25 36 2,097 39189 .397 .654 .346

912 12.08 25 302 2415 -3.120 .001 .001 17.77 17 302 1749 -2.276 .011 .011

913 12.54 512 6,422 1702202 1.387 .917 .083 20.20 318 6,422 1081905 1.839 .967 .033

914 10.06 360 3,622 629990 -1.107 .134 .134 14.97 242 3,622 417816 -1.257 .104 .104

915 8.63 3,899 33,649 69087504 5.752 0 0 13.39 2,513 33,649 45211660 6.021 0 0

916 9.12 2,098 19,131 20865701 3.152 .999 .001 13.05 1,466 19,131 14936797 4.321 1.000 0

917 16.03 481 7,709 1754946 -2.030 .021 .021 32.80 235 7,709 816437 -2.620 .004 .004

918 7.24 1,224 8,856 5504809 .950 .829 .171 10.80 820 8,856 3743759 1.541 .938 .062

919 15.10 649 9,801 3072851 -1.493 .068 .068 22.03 445 9,801 2142157 -.646 .259 .259

920 8.31 2,298 19,104 22395179 1.682 .954 .046 11.70 1,633 19,104 15992079 1.766 .961 .039

921 11.65 375 4,368 843193 .991 .839 .161 18.43 237 4,368 553116 1.829 .966 .034

922 18.57 1,225 22,744 14289112 1.560 .941 .059 31.59 720 22,744 8571698 2.179 .985 .015

923 15.71 2,128 33,427 35303565 -.590 .278 .278 28.33 1,180 33,427 19233661 -1.473 .070 .070

924 18.26 35 639 10131 -.964 .168 .168 39.94 16 639 4490 -.843 .200 .200

925 22.02 191 4,205 426074 1.460 .928 .072 41.63 101 4,205 233116 1.702 .956 .044

926 12.36 45 556 13217 .657 .744 .256 20.59 27 556 8627 1.344 .911 .089

927 11.70 379 4,433 823278 -.673 .250 .250 17.73 250 4,433 537291 -.832 .203 .203

928 14.17 538 7,623 2213194 3.186 .999 .001 24.75 308 7,623 1286938 2.926 .998 .002

929 9.76 1,611 15,716 12785028 .691 .755 .245 15.10 1,041 15,716 8059559 -.824 .205 .205

930 17.19 530 9,108 2534889 2.004 .977 .023 31.19 292 9,108 1421840 2.049 .980 .020

931 13.72 353 4,843 875809 .800 .788 .212 21.72 223 4,843 565655 1.229 .890 .110

932 13.23 246 3,255 368813 -2.141 .016 .016 19.26 169 3,255 262613 -1.018 .154 .154

933 30.50 2 61 50 -0.442 .329 .329 30.50 2 61 50 -0.442 .329 .329

934 12.55 442 5,547 1222782 -.092 .463 .463 19.00 292 5,547 822028 .445 .672 .328

935 7.37 2,674 19,694 26983438 2.220 .987 .013 10.94 1,801 19,694 18487305 3.120 .999 .001

936 7.32 1,299 9,510 6004721 -1.739 .041 .041 10.36 918 9,510 4342006 -.278 .391 .391

Table 4. Summary of interoccurrence intervals for daily precipitation thresholds of 0.25 and 0.50 inch—Continued

Seq.

no.

Daily precipitation threshold of 0.25 inch and greater Daily precipitation threshold of 0.50 inch and greater

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue
108 Atlas of Interoccurrence Intervals for Selected Thresholds of Daily Precipitation in Texas 

937 8.03 1,111 8,920 4949829 -.061 .476 .476 11.26 792 8,920 3487755 -.615 .269 .269

938 14.56 1,739 25,311 22500761 1.618 .947 .053 24.01 1,054 25,311 13583296 1.030 .849 .152

939 10.57 2,044 21,605 22541152 1.634 .949 .051 15.81 1,367 21,605 15097836 1.435 .924 .076

940 14.79 1,075 15,898 8293211 -1.675 .047 .047 24.05 661 15,898 5204908 -.419 .338 .338

941 11.28 1,458 16,452 11078624 -5.045 0 0 17.62 934 16,452 7253189 -2.962 .002 .002

942 12.57 1,045 13,131 7000071 1.135 .872 .128 20.84 630 13,131 4187386 .537 .704 .296

943 15.82 2,064 32,647 33287922 -.943 .173 .173 27.12 1,204 32,647 19630039 -.072 .471 .471

944 9.62 597 5,740 1760149 1.155 .876 .124 13.51 425 5,740 1245047 .741 .770 .230

945 13.43 1,591 21,362 17280544 1.167 .878 .122 21.05 1,015 21,362 11026667 .944 .827 .173

946 8.99 1,092 9,820 5498180 1.457 .927 .073 14.25 689 9,820 3426751 .588 .722 .278

947 12.97 1,063 13,784 7594372 2.067 .981 .019 19.92 692 13,784 5088565 3.050 .999 .001

948 15.79 77 1,216 43094 -1.208 .114 .114 26.44 46 1,216 27147 -.345 .365 .365

949 31.94 830 26,509 11160575 .723 .765 .235 64.66 410 26,509 5644184 1.354 .912 .088

950 46.40 5 232 617 .247 .598 .402 232.00 1 232 75 -.612 .270 .270

951 8.71 1,424 12,405 8711441 -.895 .186 .186 12.79 970 12,405 5880288 -1.221 .111 .111

952 10.08 489 4,929 1239050 1.078 .859 .141 15.21 324 4,929 844183 1.784 .963 .037

953 11.46 1,224 14,026 8679506 .675 .750 .250 18.36 764 14,026 5504459 1.309 .905 .095

954 11.01 629 6,922 2197379 .407 .658 .342 16.25 426 6,922 1595654 2.940 .998 .002

955 13.34 2,478 33,055 41341548 .814 .792 .208 21.04 1,571 33,055 25996493 .084 .534 .466

956 13.66 2,543 34,736 44400437 .462 .678 .322 22.13 1,570 34,736 27100627 -.421 .337 .337

957 9.21 465 4,283 982972 -.481 .315 .315 13.51 317 4,283 695189 .742 .771 .229

958 15.28 821 12,543 5197414 .468 .680 .320 25.65 489 12,543 3119807 .663 .746 .254

959 8.75 1,579 13,823 11062206 .939 .826 .174 13.22 1,046 13,823 7178770 -.393 .347 .347

960 9.41 83 781 35927 1.712 .957 .044 13.02 60 781 26210 1.592 .944 .056

961 11.36 1,769 20,090 18117512 1.426 .923 .077 18.17 1,106 20,090 11205178 .495 .690 .310

962 18.92 38 719 16025 1.848 .968 .032 32.68 22 719 10027 2.176 .985 .015

963 15.63 73 1,141 38639 -1.069 .143 .143 23.77 48 1,141 24890 -1.093 .137 .137

964 15.38 131 2,015 133481 .225 .589 .411 24.57 82 2,015 79285 -.632 .264 .264

965 12.25 832 10,194 4416043 2.066 .981 .019 19.31 528 10,194 2698163 .103 .541 .459

966 19.41 458 8,889 2022058 -.246 .403 .403 32.09 277 8,889 1239354 .193 .576 .424

967 17.86 283 5,054 680261 -1.421 .078 .078 35.34 143 5,054 346976 -.825 .205 .205

968 9.54 166 1,583 140600 1.565 .941 .059 14.52 109 1,583 93584 1.532 .937 .063

969 9.82 124 1,217 78207 .704 .759 .241 14.66 83 1,217 54587 1.275 .899 .101

970 14.01 2,337 32,743 38043512 -.474 .318 .318 22.95 1,427 32,743 23206397 -.436 .331 .331

971 10.31 167 1,722 149474 .885 .812 .188 15.11 114 1,722 103482 1.004 .842 .158

972 12.39 1,495 18,526 14662765 3.939 1.000 0 19.86 933 18,526 9176223 3.268 .999 .001

973 29.34 666 19,541 6874338 2.522 .994 .006 59.94 326 19,541 3391252 2.023 .978 .022

974 9.13 1,222 11,161 6930202 .984 .837 .163 13.87 805 11,161 4587145 1.038 .850 .150

975 9.57 1,296 12,404 7840411 -1.531 .063 .063 15.04 825 12,404 5037551 -.769 .221 .221

976 11.68 76 888 36192 1.095 .863 .137 18.12 49 888 24259 1.395 .918 .082

977 8.46 11 93 636 1.398 .919 .081 11.63 8 93 464 1.212 .887 .113

978 10.99 1,215 13,354 8452912 2.533 .994 .006 17.08 782 13,354 5523370 2.801 .997 .003

979 10.41 549 5,715 1545273 -.608 .272 .272 16.47 347 5,715 973127 -.600 .274 .274

980 11.13 321 3,573 544933 -1.544 .061 .061 16.70 214 3,573 355380 -1.785 .037 .037

981 15.00 1 15 15 1.732 .958 .042 15.00 1 15 15 1.732 .958 .042

982 11.70 33 386 7076 1.105 .865 .135 13.79 28 386 5985 .985 .838 .162

983 8.20 1,275 10,455 6649435 -.145 .442 .442 11.81 885 10,455 4725162 1.101 .864 .136

984 17.16 206 3,534 363524 -.033 .487 .487 25.42 139 3,534 249335 .310 .622 .378

985 11.43 106 1,212 68662 1.229 .890 .110 19.24 63 1,212 40522 0.844 .801 .199

986 13.38 259 3,465 455623 .429 .666 .334 19.58 177 3,465 334434 2.088 .982 .018

987 14.90 1,508 22,473 16956770 .048 .519 .481 23.19 969 22,473 10797160 -.451 .326 .326

988 11.56 203 2,346 210435 -2.869 .002 .002 16.07 146 2,346 162777 -1.036 .150 .150

Table 4. Summary of interoccurrence intervals for daily precipitation thresholds of 0.25 and 0.50 inch—Continued

Seq.

no.

Daily precipitation threshold of 0.25 inch and greater Daily precipitation threshold of 0.50 inch and greater

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue
Table 4 109

989 8.22 1,967 16,159 16015761 .596 .724 .276 12.49 1,294 16,159 10665760 1.257 .896 .104

990 9.64 1,933 18,639 19093740 4.562 1.000 0 15.14 1,231 18,639 12127475 3.471 1.000 0

991 12.53 1,483 18,574 14192376 2.033 .979 .021 18.93 981 18,574 9592248 2.868 .998 .002

992 8.48 2,356 19,989 24367254 2.929 .998 .002 12.86 1,554 19,989 16244767 3.136 .999 .001

993 11.80 116 1,369 86327 1.627 .948 .052 18.25 75 1,369 59002 2.239 .987 .013

994 13.03 474 6,177 1538239 1.914 .972 .028 20.80 297 6,177 981477 2.089 .982 .018

995 11.52 1,430 16,470 12076845 1.673 .953 .047 17.77 927 16,470 7832664 1.374 .915 .085

996 19.56 1,475 28,850 21690733 1.294 .902 .098 32.09 899 28,850 13470342 2.011 .978 .022

997 13.30 2,072 27,555 28876153 .909 .818 .182 19.75 1,395 27,555 19563985 1.159 .877 .123

998 12.23 1,743 21,324 19117467 2.076 .981 .019 19.09 1,117 21,324 12335214 2.070 .981 .019

999 12.63 289 3,649 498453 -1.610 .054 .054 18.71 195 3,649 333881 -1.489 .068 .068

1000 8.88 1,015 9,008 4572842 .016 .506 .494 13.80 653 9,008 2991465 .758 .776 .224

1001 10.00 1,972 19,714 20364699 3.667 1.000 0 15.34 1,285 19,714 13461744 3.900 1.000 0

1002 4.67 3 14 31 1.429 .923 .077 4.67 3 14 31 1.429 .923 .077

1003 15.43 1,319 20,356 14048605 2.923 .998 .002 25.87 787 20,356 8387163 2.287 .989 .011

1004 13.14 1,551 20,384 16359102 2.379 .991 .009 20.55 992 20,384 10287133 .953 .830 .170

1005 14.87 1,436 21,346 15348745 .096 .538 .462 23.61 904 21,346 9685859 .202 .580 .420

1006 9.16 309 2,830 432415 -.336 .369 .369 14.01 202 2,830 282867 -.255 .399 .399

1007 13.83 612 8,461 2515018 -1.226 .110 .110 19.41 436 8,461 1768363 -1.493 .068 .068

1008 9.83 1,414 13,894 9801188 -.145 .442 .442 14.70 945 13,894 6472045 -.753 .226 .226

1009 7.73 1,620 12,527 10183571 .252 .600 .400 12.14 1,032 12,527 6439324 -.212 .416 .416

1010 11.39 1,375 15,655 10680232 -.493 .311 .311 17.65 887 15,655 6783132 -1.188 .118 .118

1011 15.01 1,359 20,404 13992029 .587 .721 .279 23.64 863 20,404 9007648 1.175 .880 .120

1012 14.60 205 2,993 299823 -.563 .287 .287 25.15 119 2,993 185643 .802 .789 .211

1013 14.28 765 10,925 4331853 1.755 .960 .040 23.85 458 10,925 2539935 .565 .714 .286

1014 14.28 164 2,342 199431 .853 .803 .197 21.29 110 2,342 137362 1.206 .886 .114

1015 23.72 18 427 3422 -.805 .210 .210 42.70 10 427 1452 -1.752 .040 .040

1016 9.48 2,113 20,037 21528049 1.350 .911 .089 14.46 1,386 20,037 14031593 .678 .751 .249

1017 10.43 179 1,867 182363 2.117 .983 .017 16.38 114 1,867 117267 1.885 .970 .030

1018 9.68 250 2,421 287567 -1.363 .087 .087 11.26 215 2,421 247108 -1.283 .100 .100

1019 15.10 534 8,062 2095664 -1.058 .145 .145 27.33 295 8,062 1212751 .591 .723 .277

1020 15.74 374 5,888 1170747 2.120 .983 .017 24.84 237 5,888 731326 1.284 .900 .100

1021 14.58 1,664 24,253 20449628 .949 .829 .171 23.85 1,017 24,253 12359936 .122 .549 .451

1022 9.52 1,037 9,875 5062573 -.628 .265 .265 13.83 714 9,875 3540028 .192 .576 .424

1023 9.49 710 6,740 2283249 -2.111 .017 .017 14.46 466 6,740 1493655 -1.828 .034 .034

1024 10.30 1,139 11,727 6672767 -.050 .480 .480 15.17 773 11,727 4615638 .884 .811 .189

1025 13.20 214 2,824 288493 -1.147 .126 .126 19.61 144 2,824 189995 -1.363 .086 .086

1026 9.59 1,993 19,114 19700443 2.652 .996 .004 14.94 1,279 19,114 12594279 1.880 .970 .030

1027 13.96 484 6,758 1682418 1.095 .863 .137 22.45 301 6,758 1031087 .414 .661 .339

1028 14.62 1,872 27,372 25937652 .929 .823 .177 23.99 1,141 27,372 16433883 3.065 .999 .001

1029 11.11 1,400 15,548 11158936 1.640 .949 .051 17.75 876 15,548 7116915 2.310 .990 .010

1030 10.06 1,217 12,246 7444940 -.055 .478 .478 15.90 770 12,246 4863667 1.519 .936 .064

1031 19.67 129 2,538 142080 -2.598 .005 .005 39.05 65 2,538 68257 -2.409 .008 .008

1032 12.16 2,997 36,443 54626381 .029 .511 .489 19.70 1,850 36,443 33535070 -.386 .350 .350

1033 7.80 2,749 21,434 29544646 .258 .602 .398 11.55 1,856 21,434 20276426 1.447 .926 .074

1034 16.91 128 2,164 144174 .803 .789 .211 28.10 77 2,164 85459 .391 .652 .348

1035 14.42 2,344 33,805 39603497 -.034 .487 .487 23.69 1,427 33,805 24231723 .303 .619 .381

1036 6.54 82 536 22444 .334 .631 .369 9.40 57 536 14164 -.952 .171 .171

1037 11.83 36 426 7721 0.072 .529 .471 18.52 23 426 3911 -1.675 .047 .047

1038 11.97 290 3,471 526390 1.354 .912 .088 17.89 194 3,471 351925 1.092 .863 .138

1039 27.57 254 7,002 883876 -.167 .434 .434 68.65 102 7,002 384944 1.364 .914 .086

1040 33.35 206 6,871 764478 1.994 .977 .023 70.11 98 6,871 375252 1.965 .975 .025

Table 4. Summary of interoccurrence intervals for daily precipitation thresholds of 0.25 and 0.50 inch—Continued

Seq.

no.

Daily precipitation threshold of 0.25 inch and greater Daily precipitation threshold of 0.50 inch and greater

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue
110 Atlas of Interoccurrence Intervals for Selected Thresholds of Daily Precipitation in Texas 

1041 41.18 85 3,500 143163 -.600 .274 .274 97.22 36 3,500 61780 -.201 .420 .420

1042 6.78 1,830 12,414 11291906 -.436 .331 .331 9.55 1,300 12,414 8052989 -.125 .450 .450

1043 23.55 20 471 3827 -1.452 .073 .073 42.82 11 471 1449 -2.531 .006 .006

1044 17.09 479 8,188 2122627 3.124 .999 .001 29.88 274 8,188 1216279 2.416 .992 .008

1045 16.96 1,179 19,999 12396330 3.062 .999 .001 29.72 673 19,999 7140937 2.746 .997 .003

1046 11.30 151 1,706 128909 .018 .507 .493 18.15 94 1,706 82404 .465 .679 .321

1047 12.44 1,625 20,211 17278002 3.642 1.000 0 19.99 1,011 20,211 10747107 2.859 .998 .002

1048 13.66 879 12,010 5077204 -1.957 .025 .025 20.92 574 12,010 3417667 -.352 .363 .363

1049 12.34 397 4,897 959633 -.441 .330 .330 18.69 262 4,897 653756 .535 .704 .296

1050 7.32 1,646 12,043 10261242 2.480 .993 .007 10.69 1,127 12,043 7093797 2.635 .996 .004

1051 14.45 1,236 17,865 10881243 -.879 .190 .190 22.90 780 17,865 6766015 -1.398 .081 .081

1052 14.20 51 724 18159 -.203 .420 .420 24.97 29 724 11014 .459 .677 .323

1053 7.40 141 1,044 74185 .163 .565 .435 10.34 101 1,044 51409 -.434 .332 .332

1054 20.33 3 61 75 -.541 .294 .294 30.50 2 61 24 -1.486 .069 .069

1055 8.89 376 3,344 631239 .137 .555 .445 12.48 268 3,344 464975 1.068 .857 .143

1056 16.42 128 2,102 149940 2.245 .988 .012 29.19 72 2,102 82651 1.356 .912 .088

1057 18.82 27 508 7068 .276 .609 .391 39.08 13 508 3595 .554 .710 .290

1058 10.98 3,209 35,247 57276842 1.254 .895 .105 16.87 2,089 35,247 37311044 1.066 .857 .143

1059 15.54 46 715 15457 -.706 .240 .240 23.07 31 715 9736 -1.172 .121 .121

1060 12.85 1,886 24,233 23119542 .882 .811 .189 20.68 1,172 24,233 14510966 1.296 .903 .097

1061 11.38 58 660 19208 .047 .519 .481 22.76 29 660 9144 -.415 .339 .339

1062 20.19 103 2,080 87976 -3.142 .001 .001 33.55 62 2,080 54874 -2.032 .021 .021

1063 24.11 990 23,869 12122449 1.417 .922 .078 43.80 545 23,869 6788159 1.765 .961 .039

1064 27.53 45 1,239 28510 .264 .604 .396 45.89 27 1,239 17653 .499 .691 .309

1065 12.97 468 6,070 1418740 -.043 .483 .483 20.58 295 6,070 923950 .951 .829 .171

1066 10.33 1,076 11,113 6090819 1.065 .856 .144 16.06 692 11,113 4011757 1.975 .976 .024

1067 11.91 77 917 40436 2.209 .986 .014 16.09 57 917 29821 1.845 .967 .033

1068 14.61 49 716 17022 -.359 .360 .360 28.64 25 716 8095 -.827 .204 .204

1069 16.52 328 5,418 867495 -.743 .229 .229 28.67 189 5,418 492291 -.917 .180 .180

1070 13.77 2,559 35,225 44493411 -1.122 .131 .131 22.02 1,600 35,225 27978640 -.495 .310 .310

1071 9.91 1,981 19,631 19707976 1.045 .852 .148 15.62 1,257 19,631 12850638 2.551 .995 .005

1072 12.00 139 1,668 112439 -.614 .270 .270 16.35 102 1,668 84766 -.062 .475 .475

1073 70.67 3 212 357 .368 .644 .356 212.00 1 212 130 .392 .653 .347

1074 9.34 3,223 30,105 48967986 .920 .821 .179 14.13 2,130 30,105 32662064 1.497 .933 .067

1075 14.30 181 2,589 237494 .317 .624 .376 22.91 113 2,589 147868 .200 .579 .421

1076 12.11 1,490 18,047 13346504 -.490 .312 .312 19.26 937 18,047 8545305 .566 .714 .286

1077 11.77 292 3,438 518010 .947 .828 .172 17.28 199 3,438 360123 1.289 .901 .099

1078 19.31 1,425 27,513 19688009 .284 .612 .388 35.23 781 27,513 10640997 -.463 .322 .322

1079 12.70 2,464 31,290 39452855 2.015 .978 .022 20.74 1,509 31,290 24030581 1.204 .886 .114

1080 12.41 39 484 10130 .793 .786 .214 20.17 24 484 6549 1.083 .860 .140

1081 13.69 1,551 21,232 16738975 1.133 .871 .129 23.88 889 21,232 9637910 1.096 .863 .137

1082 13.72 998 13,695 7169346 2.687 .996 .004 23.37 586 13,695 4243691 2.414 .992 .008

1083 22.01 701 15,430 5464314 .476 .683 .317 36.65 421 15,430 3392734 1.584 .943 .057

1084 9.36 130 1,217 77637 -.367 .357 .357 14.66 83 1,217 49513 -.310 .378 .378

1085 9.03 4,026 36,335 74023922 1.325 .907 .093 13.75 2,643 36,335 48491084 .880 .810 .190

1086 19.20 263 5,049 694129 1.277 .899 .101 30.42 166 5,049 416587 -.132 .447 .447

1087 24.65 570 14,050 4000169 -.042 .483 .483 55.98 251 14,050 1731200 -.499 .309 .309

1088 7.71 292 2,252 331126 .210 .583 .417 10.88 207 2,252 236362 .351 .637 .363

1089 19.13 62 1,186 33651 -1.156 .124 .124 27.58 43 1,186 22985 -1.120 .131 .131

1090 13.33 764 10,180 3938128 .608 .728 .272 20.90 487 10,180 2532555 .828 .796 .204

1091 14.41 1,367 19,700 13748064 1.347 .911 .089 26.62 740 19,700 7353021 .414 .660 .340

1092 5.13 24 123 949 -3.030 .001 .001 7.24 17 123 717 -2.244 .012 .012

Table 4. Summary of interoccurrence intervals for daily precipitation thresholds of 0.25 and 0.50 inch—Continued

Seq.

no.

Daily precipitation threshold of 0.25 inch and greater Daily precipitation threshold of 0.50 inch and greater

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue
Table 4 111

1093 7.58 628 4,757 1525800 .933 .824 .176 10.96 434 4,757 1066724 1.204 .886 .114

1094 12.31 2,097 25,807 27290053 .678 .751 .249 18.78 1,374 25,807 18196218 1.690 .955 .045

1095 9.24 214 1,978 206099 -.664 .253 .253 14.76 134 1,978 129617 -.440 .330 .330

1096 16.01 1,193 19,104 11613874 1.146 .874 .126 28.73 665 19,104 6564377 1.493 .932 .068

1097 9.73 1,955 19,028 19745013 4.715 1.000 0 13.94 1,365 19,028 14138045 5.674 0 0

1098 12.16 1,215 14,774 8900839 -.500 .309 .309 19.26 767 14,774 5671558 .049 .519 .481

1099 20.60 10 206 666 -1.936 .026 .026 51.50 4 206 226 -1.564 .059 .059

1100 12.21 231 2,820 290486 -2.847 .002 .002 19.58 144 2,820 185009 -1.846 .032 .032

1101 9.90 2,948 29,198 43002249 -.078 .469 .469 15.37 1,900 29,198 27727546 -.029 .489 .489

1102 15.51 2,035 31,561 31656430 -1.112 .133 .133 26.06 1,211 31,561 18910572 -.630 .265 .265

1103 38.62 271 10,466 1403531 -.294 .384 .384 84.40 124 10,466 654316 .161 .564 .436

1104 10.75 727 7,812 2996753 2.584 .995 .005 16.04 487 7,812 1997383 1.912 .972 .028

1105 9.15 1,448 13,243 9864724 1.903 .971 .029 14.85 892 13,243 6109634 1.780 .962 .038

1106 15.68 1,434 22,491 16414557 1.174 .880 .120 25.70 875 22,491 9931057 .475 .683 .317

1107 17.50 92 1,610 71474 -.580 .281 .281 29.27 55 1,610 37437 -1.984 .024 .024

1108 -- -- -- -- -- -- -- -- -- -- -- -- -- --

1109 13.23 264 3,493 439988 -1.287 .099 .099 20.19 173 3,493 281385 -1.565 .059 .059

1110 16.71 210 3,510 334833 -2.296 .011 .011 25.44 138 3,510 212132 -2.525 .006 .006

1111 15.86 142 2,252 152374 -.971 .166 .166 28.51 79 2,252 84072 -.845 .199 .199

1112 8.77 1,370 12,016 8300879 .545 .707 .293 13.31 903 12,016 5549933 1.196 .884 .116

1113 15.01 1,965 29,498 28698962 -.749 .227 .227 26.87 1,098 29,498 16024037 -.604 .273 .273

1114 10.85 1,117 12,124 6778999 .066 .526 .474 17.00 713 12,124 4233279 -.952 .171 .171

1115 14.42 403 5,813 1250228 2.342 .990 .010 24.95 233 5,813 692392 .593 .723 .277

1116 8.81 165 1,453 110458 -1.747 .040 .040 11.53 126 1,453 83676 -1.670 .047 .047

1117 10.88 1,445 15,727 11533577 .990 .839 .161 17.36 906 15,727 7113805 -.077 .469 .469

1118 11.11 72 800 31584 1.421 .922 .078 18.18 44 800 19672 1.353 .912 .088

1119 10.79 703 7,586 2645359 -.364 .358 .358 17.52 433 7,586 1582730 -1.309 .095 .095

1120 15.29 1,600 24,462 19485050 -.299 .382 .382 25.80 948 24,462 11488929 -.488 .313 .313

1121 13.91 2,133 29,675 32140186 1.243 .893 .107 22.21 1,336 29,675 19818501 -.014 .494 .494

1122 17.31 59 1,021 30769 .287 .613 .387 24.31 42 1,021 20054 -.726 .234 .234

1123 11.41 1,998 22,804 23092564 1.058 .855 .145 18.89 1,207 22,804 13822865 .265 .605 .395

1124 9.72 141 1,371 90941 -1.216 .112 .112 15.23 90 1,371 54260 -1.980 .024 .024

1125 12.59 224 2,820 339615 1.951 .974 .026 18.19 155 2,820 221252 .267 .605 .395

1126 22.59 171 3,863 292259 -2.608 .005 .005 32.46 119 3,863 215064 -1.215 .112 .112

1127 16.20 1,648 26,696 21645124 -1.126 .130 .130 26.88 993 26,696 12571074 -2.815 .002 .002

1128 16.15 597 9,641 2868482 -.138 .445 .445 26.13 369 9,641 1736798 -.785 .216 .216

1129 21.29 169 3,598 322896 1.397 .919 .081 38.28 94 3,598 174209 .507 .694 .306

1130 47.19 16 755 4758 -1.471 .071 .071 83.89 9 755 3055 -.524 .300 .300

1131 10.08 1,374 13,853 9725930 1.409 .921 .079 15.83 875 13,853 6315066 2.150 .984 .016

1132 21.09 33 696 12279 .689 .754 .246 31.64 22 696 7936 .297 .617 .383

1133 11.59 871 10,098 4326753 -.824 .205 .205 17.50 577 10,098 2906937 -.091 .464 .464

1134 15.93 43 685 15213 .374 .646 .354 24.46 28 685 10257 .638 .738 .262

1135 7.74 102 789 39091 -.499 .309 .309 9.39 84 789 30492 -1.268 .103 .103

1136 17.08 1,632 27,875 23043573 .915 .820 .180 32.19 866 27,875 12401283 1.400 .919 .081

1137 11.42 1,677 19,145 16312357 1.146 .874 .126 18.18 1,053 19,145 10224690 .808 .790 .210

1138 21.85 113 2,469 135136 -.576 .282 .282 47.48 52 2,469 68216 .783 .783 .217

1139 33.88 92 3,117 139526 -.447 .328 .328 52.83 59 3,117 81364 -1.532 .063 .063

1140 16.07 693 11,137 3622667 -2.792 .003 .003 26.71 417 11,137 2222638 -1.515 .065 .065

1141 8.41 2,373 19,965 24040206 1.253 .895 .105 12.75 1,566 19,965 16208211 2.524 .994 .006

1142 8.50 3,851 32,715 65385948 4.084 1.000 0 12.35 2,649 32,715 44393476 2.186 .986 .014

1143 19.90 453 9,015 2058911 .307 .621 .379 34.54 261 9,015 1190768 .340 .633 .367

1144 15.39 156 2,401 189712 .281 .611 .389 21.63 111 2,401 137327 .558 .711 .289

Table 4. Summary of interoccurrence intervals for daily precipitation thresholds of 0.25 and 0.50 inch—Continued

Seq.

no.

Daily precipitation threshold of 0.25 inch and greater Daily precipitation threshold of 0.50 inch and greater

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue
112 Atlas of Interoccurrence Intervals for Selected Thresholds of Daily Precipitation in Texas 

1145 18.32 78 1,429 68641 3.544 1.000 0 30.40 47 1,429 41846 2.922 .998 .002

1146 16.13 1,651 26,623 21842531 -.432 .333 .333 29.22 911 26,623 12078881 -.207 .418 .418

1147 15.07 412 6,208 1335545 1.559 .940 .060 26.19 237 6,208 755263 .711 .761 .239

1148 15.28 851 13,000 5771933 2.196 .986 .014 27.08 480 13,000 3187039 .815 .793 .207

1149 12.55 963 12,084 5932563 1.054 .854 .146 20.38 593 12,084 3747954 1.943 .974 .026

1150 17.39 773 13,443 5221984 .243 .596 .404 31.56 426 13,443 2883370 .250 .599 .401

1151 8.16 140 1,142 79867 -.019 .493 .493 13.13 87 1,142 48139 -.500 .309 .309

1152 10.51 2,518 26,466 33612692 .762 .777 .223 16.51 1,603 26,466 21709645 1.625 .948 .052

1153 8.12 60 487 15029 .385 .650 .350 11.33 43 487 10488 .019 .508 .492

1154 12.18 1,071 13,041 7139884 1.270 .898 .102 20.16 647 13,041 4271122 .547 .708 .292

1155 10.37 132 1,369 76309 -3.093 .001 .001 15.21 90 1,369 51985 -2.566 .005 .005

1156 11.61 1,121 13,013 7427614 1.064 .856 .144 18.59 700 13,013 4663898 1.100 .864 .136

1157 13.88 1,300 18,047 11938863 1.109 .866 .134 21.64 834 18,047 7713833 1.251 .895 .105

1158 8.97 397 3,562 713471 .313 .623 .377 12.91 276 3,562 512816 1.245 .893 .107

1159 10.37 3,552 36,849 65799398 .561 .713 .287 15.82 2,330 36,849 42847201 -.160 .437 .437

1160 13.60 103 1,401 75278 .762 .777 .223 21.55 65 1,401 49672 1.270 .898 .102

1161 16.02 357 5,720 1086964 2.114 .983 .017 24.34 235 5,720 704913 1.296 .903 .097

1162 25.75 47 1,210 31977 1.479 .930 .070 71.18 17 1,210 10726 .306 .620 .380

1163 30.10 105 3,160 152851 -1.396 .081 .081 79.00 40 3,160 55703 -1.300 .097 .097

1164 9.27 2,066 19,160 20575180 3.114 .999 .001 13.94 1,375 19,160 13463232 1.418 .922 .078

1165 15.12 657 9,934 3387783 1.693 .955 .045 24.77 401 9,934 2059370 1.177 .880 .120

1166 7.09 1,691 11,989 10352925 1.519 .936 .064 10.60 1,131 11,989 6943396 1.406 .920 .080

1167 7.67 880 6,751 2965875 -.079 .468 .468 11.95 565 6,751 1929947 .492 .689 .311

1168 20.65 121 2,498 161488 1.306 .904 .096 32.44 77 2,498 100338 .658 .745 .255

1169 28.39 44 1,249 28838 .569 .715 .285 62.45 20 1,249 13147 .408 .658 .342

1170 7.91 2,091 16,537 18160387 3.990 1.000 0 11.98 1,380 16,537 11852163 2.490 .994 .006

1171 10.11 1,211 12,247 7414870 -.006 .498 .498 15.56 787 12,247 4730153 -.898 .185 .185

1172 10.33 1,874 19,365 19012891 3.586 1.000 0 14.83 1,306 19,365 13205669 2.774 .997 .003

1173 13.84 1,719 23,783 20630027 .662 .746 .254 22.72 1,047 23,783 12492062 .188 .574 .426

1174 14.68 346 5,080 888596 .358 .640 .360 24.08 211 5,080 542295 .298 .617 .383

1175 12.91 2,101 27,125 28845723 .978 .836 .164 21.34 1,271 27,125 17458783 .791 .785 .215

1176 12.82 51 654 14104 -1.908 .028 .028 20.44 32 654 8888 -1.476 .070 .070

1177 13.53 105 1,421 75325 .172 .568 .432 18.46 77 1,421 54051 -.183 .427 .427

1178 12.58 1,419 17,848 13134627 2.429 .992 .008 19.25 927 17,848 8491821 1.398 .919 .081

1179 15.18 1,155 17,533 10122726 -.015 .494 .494 24.73 709 17,533 6314826 .737 .769 .231

1180 16.42 102 1,675 86765 .274 .608 .392 27.46 61 1,675 52706 .429 .666 .334

1181 33.47 36 1,205 17402 -2.055 .020 .020 70.88 17 1,205 10618 .262 .603 .397

1182 7.27 1,332 9,681 6584043 1.338 .910 .090 10.69 906 9,681 4434929 .588 .722 .278

1183 8.38 2,339 19,606 23536633 2.219 .987 .013 13.03 1,505 19,606 15246996 2.248 .988 .012

1184 33.75 238 8033 902824 -1.484 .069 .069 77.99 103 8,033 381604 -1.364 .086 .086

1185 11.23 762 8556 3231864 -.410 .341 .341 19.90 430 8,556 1923115 1.632 .949 .051

1186 8.00 753 6027 2272209 .064 .525 .475 12.33 489 6,027 1508780 .914 .820 .180

1187 7.11 1,615 11,476 9252299 -.109 .456 .456 10.55 1,088 11,476 6311464 .627 .735 .265

1188 33.13 302 10,006 1505352 -.111 .456 .456 69.49 144 10,006 758005 1.084 .861 .139

1189 14.67 1,306 19,158 12417469 -.464 .321 .321 23.05 831 19,158 8241288 1.763 .961 .039

1190 8.51 2,240 19,072 21815362 1.745 .960 .040 12.81 1,489 19,072 14673652 2.234 .987 .013

1191 25.86 28 724 8673 -1.323 .093 .093 45.25 16 724 4793 -1.195 .116 .116

1192 14.87 436 6,484 1444309 .788 .785 .215 24.38 266 6,484 907068 1.464 .928 .072

1193 10.32 740 7,637 2881212 0.926 .823 .177 14.72 519 7,637 2026463 0.889 .813 .187

1194 9.45 882 8,332 3606009 -.958 .169 .169 13.82 603 8,332 2559276 .799 .788 .212

1195 7.44 299 2,224 345035 1.130 .871 .129 11.71 190 2,224 214765 .394 .653 .347

1196 8.65 743 6,424 2462931 1.512 .935 .065 12.87 499 6,424 1623796 .507 .694 .306

Table 4. Summary of interoccurrence intervals for daily precipitation thresholds of 0.25 and 0.50 inch—Continued

Seq.

no.

Daily precipitation threshold of 0.25 inch and greater Daily precipitation threshold of 0.50 inch and greater

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue
Table 4 113

1197 10.33 1,918 19,815 19484985 1.926 .973 .027 16.11 1,230 19,815 12629095 2.208 .986 .014

1198 14.83 612 9,076 2916124 2.143 .984 .016 24.07 377 9,076 1823768 2.220 .987 .013

1199 36.00 10 360 1792 -.024 .490 .490 51.43 7 360 1417 .571 .716 .284

1200 13.45 1,070 14,391 7822422 .907 .818 .182 22.77 632 14,391 4708117 1.537 .938 .062

1201 17.92 107 1,917 104608 .358 .640 .360 33.63 57 1,917 54616 -.004 .498 .498

1202 15.93 1,218 19,400 12417363 3.084 .999 .001 29.57 656 19,400 6758811 2.758 .997 .003

1203 14.36 1,093 15,694 8181126 -2.642 .004 .004 23.32 673 15,694 4952706 -2.794 .003 .003

1204 14.77 1,048 15,481 8589418 3.300 1.000 0 25.98 596 15,481 4954175 3.124 .999 .001

1205 7.90 821 6,485 2628384 -.628 .265 .265 11.90 545 6,485 1785157 .412 .660 .340

1206 8.19 1,294 10,592 6920137 .610 .729 .271 13.13 807 10,592 4273141 -.008 .497 .497

1207 8.92 684 6,104 2054307 -.722 .235 .235 13.60 449 6,104 1357802 -.336 .368 .368

1208 17.04 1,145 19,506 11171525 .023 .509 .491 31.26 624 19,506 6134901 .349 .636 .364

1209 -- -- -- -- -- -- -- -- -- -- -- -- -- --

1210 12.00 309 3,709 562416 -.565 .286 .286 17.09 217 3,709 389650 -.810 .209 .209

1211 15.44 1,817 28,061 25307987 -.537 .296 .296 24.99 1,123 28,061 15751309 -.018 .493 .493

1212 15.41 625 9,634 3020313 .139 .555 .445 25.83 373 9,634 1837702 .763 .777 .223

1213 13.69 400 5,474 1045075 -1.573 .058 .058 23.29 235 5,474 646187 .124 .549 .451

1214 12.93 56 724 19110 -.743 .229 .229 19.05 38 724 12408 -1.046 .148 .148

1215 22.41 381 8,537 1515566 -2.302 .011 .011 49.06 174 8,537 677303 -2.012 .022 .022

1216 21.01 1,201 25,234 15142904 -.040 .484 .484 40.70 620 25,234 7511778 -1.713 .043 .043

1217 10.45 1,257 13,130 8187847 -.479 .316 .316 15.80 831 13,130 5448967 -.060 .476 .476

1218 10.75 304 3,269 495285 -.097 .461 .461 14.66 223 3,269 366093 .114 .545 .455

1219 9.95 1,974 19,632 19804405 1.698 .955 .045 15.36 1,278 19,632 12966935 2.083 .981 .019

1220 25.76 812 20,914 8672032 1.052 .853 .147 57.61 363 20,914 3894682 .859 .805 .195

1221 16.06 366 5,877 1119550 1.358 .913 .087 23.41 251 5,877 764884 1.017 .845 .155

1222 22.90 10 229 837 -1.473 .070 .070 57.25 4 229 427 -.235 .407 .407

1223 11.22 488 5,476 1354716 .532 .703 .297 17.17 319 5,476 909725 1.286 .901 .099

1224 11.05 179 1,978 172034 -.654 .257 .257 18.84 105 1,978 103287 -.095 .462 .462

1225 11.47 231 2,649 315626 .832 .797 .203 17.78 149 2,649 201974 .495 .690 .310

1226 16.06 1,364 21,901 14297347 -2.737 .003 .003 30.25 724 21,901 7466197 -2.716 .003 .003

1227 11.46 545 6,246 1701337 -.017 .493 .493 17.95 348 6,246 1056859 -.890 .187 .187

1228 13.24 1,893 25,070 24219294 1.558 .940 .060 20.82 1,204 25,070 14956490 -.540 .295 .295

1229 10.14 1,456 14,762 11037717 1.790 .963 .037 15.81 934 14,762 7040427 1.125 .870 .130

1230 10.29 1,396 14,360 9947560 -.489 .312 .312 16.78 856 14,360 6185592 .326 .628 .372

1231 10.39 75 779 30548 .686 .754 .246 16.94 46 779 19068 .755 .775 .225

1232 9.03 108 975 57171 1.546 .939 .061 15.98 61 975 32375 1.200 .885 .115

1233 11.70 455 5,323 1241481 .931 .824 .176 19.86 268 5,323 740086 1.066 .857 .143

1234 13.09 853 11,164 4967944 2.194 .986 .014 20.34 549 11,164 3254101 2.511 .994 .006

1235 11.47 361 4,140 772099 1.093 .863 .137 19.53 212 4,140 449572 .617 .731 .269

1236 13.35 166 2,216 172094 -1.436 .076 .076 18.31 121 2,216 122571 -1.634 .051 .051

1237 9.74 1,349 13,142 9235706 2.666 .996 .004 15.25 862 13,142 5939802 2.474 .993 .007

1238 10.80 2,359 25,474 30350053 .850 .802 .198 17.12 1,488 25,474 19187193 .827 .796 .204

1239 10.43 1,443 15,049 11134814 1.678 .953 .047 16.30 923 15,049 6886661 -.443 .329 .329

1240 18.22 103 1,877 88482 -1.488 .068 .068 29.33 64 1,877 54018 -1.395 .082 .082

1241 9.05 1,997 18,072 18498402 1.945 .974 .026 14.26 1,267 18,072 11577561 .694 .756 .244

1242 10.83 69 747 26812 .581 .719 .281 16.60 45 747 18006 .829 .796 .204

1243 7.30 2,412 17,604 21563270 1.334 .909 .091 11.04 1,595 17,604 14356563 1.564 .941 .059

1244 8.95 2,139 19,152 20935811 1.771 .962 .038 14.31 1,338 19,152 13213402 1.981 .976 .024

1245 16.25 1,167 18,958 11500746 2.347 .991 .009 26.04 728 18,958 7250053 2.366 .991 .009

1246 19.27 120 2,312 125697 -1.781 .037 .037 32.56 71 2,312 75642 -1.144 .126 .126

1247 15.06 1,008 15,182 7599956 -.372 .355 .355 24.25 626 15,182 4636474 -1.053 .146 .146

1248 6.78 9 61 268 -.123 .451 .451 7.63 8 61 244 0 .500 .500

Table 4. Summary of interoccurrence intervals for daily precipitation thresholds of 0.25 and 0.50 inch—Continued

Seq.

no.

Daily precipitation threshold of 0.25 inch and greater Daily precipitation threshold of 0.50 inch and greater

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue
114 Atlas of Interoccurrence Intervals for Selected Thresholds of Daily Precipitation in Texas 

1249 10.82 1,139 12,327 7143647 1.028 .848 .152 17.24 715 12,327 4607504 2.108 .982 .018

1250 9.79 3,764 36,857 70367661 1.536 .938 .062 15.02 2,454 36,857 46189486 1.833 .967 .033

1251 14.58 76 1,108 34712 -2.651 .004 .004 25.18 44 1,108 19354 -2.367 .009 .009

1252 10.81 3,280 35,470 59282760 1.896 .971 .029 16.96 2,092 35,470 38018075 1.957 .975 .025

1253 10.58 422 4,465 999139 2.154 .984 .016 14.45 309 4,465 721673 1.405 .920 .080

1254 10.13 45 456 11284 1.160 .877 .123 14.25 32 456 7626 .443 .671 .329

1255 11.59 1,159 13,428 7681787 -.756 .225 .225 17.72 758 13,428 4910502 -1.675 .047 .047

1256 14.86 1,378 20,473 13796578 -1.410 .079 .079 23.95 855 20,473 8704901 -.274 .392 .392

1257 15.52 1,258 19,529 12616559 1.665 .952 .048 27.66 706 19,529 7218973 2.171 .985 .015

1258 9.69 375 3,633 670787 -.512 .304 .304 14.36 253 3,633 466938 .441 .671 .329

1259 28.63 8 229 1087 .915 .820 .180 57.25 4 229 658 1.513 .935 .065

1260 9.10 2,395 21,784 26689199 1.959 .975 .025 13.96 1,561 21,784 17363924 1.455 .927 .073

1261 14.76 554 8,179 2201408 -1.155 .124 .124 24.27 337 8,179 1385536 .170 .568 .432

1262 12.41 93 1,154 53341 -.100 .460 .460 20.61 56 1,154 30845 -.589 .278 .278

1263 6.88 75 516 19978 .487 .687 .313 9.21 56 516 14347 -.091 .464 .464

1264 18.21 85 1,548 67002 .294 .616 .384 28.67 54 1,548 47254 1.662 .952 .048

1265 8.36 413 3454 696464 -.829 .204 .204 12.42 278 3,454 491148 .664 .747 .253

1266 10.47 1,819 19,044 17773966 1.934 .973 .027 16.53 1,152 19,044 11306407 1.806 .965 .035

1267 13.40 1,006 13,484 6737185 -.367 .357 .357 20.65 653 13,484 4283253 -1.199 .115 .115

1268 14.04 1,222 17,161 10837138 2.031 .979 .021 21.72 790 17,161 6692184 -.621 .267 .267

1269 -- -- -- -- -- -- -- -- -- -- -- -- -- --

1270 11.76 186 2,187 200636 -.320 .374 .374 19.18 114 2,187 123050 -.239 .406 .406

1271 12.31 2,849 35,073 50120614 .294 .616 .384 19.55 1,794 35,073 30969360 -1.145 .126 .126

1272 14.10 283 3,991 517565 -2.433 .007 .007 21.93 182 3,991 329275 -2.182 .015 .015

1273 12.72 749 9,529 3645000 1.015 .845 .155 19.85 480 9,529 2264787 -.368 .356 .356

1274 7.86 783 6,153 2423725 .298 .617 .383 11.27 546 6,153 1707461 .667 .748 .252

1275 7.44 485 3,606 849934 -1.070 .142 .142 10.70 337 3,606 605214 -.125 .450 .450

1276 8.92 620 5,527 1750637 .938 .826 .174 14.06 393 5,527 1123985 1.199 .885 .115

1277 10.20 251 2,560 283733 -3.207 .001 .001 12.49 205 2,560 250390 -1.135 .128 .128

1278 8.58 3,378 28,977 49543026 1.236 .892 .108 12.69 2,283 28,977 33058287 -.047 .481 .481

1279 19.75 76 1,501 51586 -1.443 .074 .074 33.36 45 1,501 28902 -1.676 .047 .047

1280 13.83 389 5,379 1129092 2.706 .997 .003 24.34 221 5,379 650855 2.447 .993 .007

1281 9.50 653 6,203 2015262 -.219 .413 .413 14.98 414 6,203 1267370 -.457 .324 .324

1282 12.90 19 245 3061 2.379 .991 .009 22.27 11 245 1617 1.149 .875 .125

1283 14.03 373 5,233 979295 .115 .546 .454 20.68 253 5,233 715445 2.225 .987 .013

1284 8.99 1,087 9,769 5286111 -.251 .401 .401 12.94 755 9,769 3691382 .046 .518 .482

1285 27.49 766 21,056 8096794 .192 .576 .424 51.74 407 21,056 4242807 -.343 .366 .366

1286 8.62 2,123 18,295 19916912 2.041 .979 .021 12.38 1,478 18,295 13725523 1.012 .844 .156

1287 20.14 297 5,980 870702 -.583 .280 .280 32.15 186 5,980 542667 -.572 .284 .284

1288 13.90 867 12,048 4960996 -2.557 .005 .005 22.99 524 12,048 2963659 -2.423 .008 .008

1289 15.01 924 13,868 6427615 .169 .567 .433 23.08 601 13,868 4112206 -.562 .287 .287

1290 13.24 108 1,430 77830 .142 .557 .443 26.00 55 1,430 42225 .947 .828 .172

1291 12.28 99 1,216 62548 .675 .750 .250 20.27 60 1,216 37207 .267 .605 .395

1292 8.61 2,285 19,665 23041953 2.118 .983 .017 12.89 1,526 19,665 15289857 1.287 .901 .099

1293 11.81 1,443 17,041 12371676 .410 .659 .341 18.32 930 17,041 8029743 .704 .759 .241

1294 12.94 391 5,058 980505 -.289 .386 .386 19.45 260 5,058 638370 -.814 .208 .208

1295 8.51 75 638 27236 2.076 .981 .019 11.39 56 638 22140 3.103 .999 .001

1296 6.84 622 4,257 1313942 -.326 .372 .372 10.04 424 4,257 903377 .035 .514 .486

1297 14.04 193 2,709 215104 -4.263 0 0 23.35 116 2,709 139889 -2.046 .020 .020

1298 9.71 153 1,485 105802 -1.471 .071 .071 14.28 104 1,485 65888 -2.592 .005 .005

1299 7.46 1,299 9,696 6303542 .059 .524 .476 11.15 870 9,696 4275821 .703 .759 .241

1300 10.11 18 182 1948 1.391 .918 .082 20.22 9 182 978 1.009 .843 .157

Table 4. Summary of interoccurrence intervals for daily precipitation thresholds of 0.25 and 0.50 inch—Continued

Seq.

no.

Daily precipitation threshold of 0.25 inch and greater Daily precipitation threshold of 0.50 inch and greater

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue
Table 4 115

1301 10.13 2,743 27,787 38738166 1.496 .933 .067 15.71 1,769 27,787 25040330 1.372 .915 .085

1302 10.97 1,704 18,695 16438350 2.290 .989 .011 17.14 1,091 18,695 10621370 2.374 .991 .009

1303 11.64 25 291 3301 -.801 .212 .212 15.32 19 291 2343 -1.151 .125 .125

1304 10.49 347 3,640 613074 -.943 .173 .173 16.70 218 3,640 391833 -.318 .375 .375

1305 33.97 667 22,655 8004215 2.657 .996 .004 79.77 284 22,655 3352707 1.231 .891 .109

1306 19.91 752 14,972 5788249 1.340 .910 .090 31.59 474 14,972 3605392 .606 .728 .272

Table 4. Summary of interoccurrence intervals for daily precipitation thresholds of 0.25 and 0.50 inch—Continued

Seq.

no.

Daily precipitation threshold of 0.25 inch and greater Daily precipitation threshold of 0.50 inch and greater

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue
116 Atlas of Interoccurrence Intervals for Selected Thresholds of Daily Precipitation in Texas 

Table 5. Summary of interoccurrence intervals for daily precipitation thresholds of 0.75 and 1.0 inch—Continued

Seq.

no.

Daily precipitation threshold of 0.75 inch and greater Daily precipitation threshold of 1.0 inch and greater

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue

1 51.22 381 19,514 3816445 0.901 .816 .184 80.97 241 19,514 2356211 0.055 .522 .478

2 60.00 4 240 324 -1.126 .130 .130 80.00 3 240 202 -1.317 .094 .094

3 36.93 534 19,720 5374840 .833 .798 .202 57.66 342 19,720 3313512 -.557 .289 .289

4 39.51 213 8,416 869674 -.751 .226 .226 57.25 147 8,416 603669 -.506 .306 .306

5 52.04 365 18,993 3780885 3.004 .999 .001 78.81 241 18,993 2509901 2.599 .995 .005

6 43.48 81 3,522 130253 -1.354 .088 .088 71.88 49 3,522 79066 -1.015 .155 .155

7 29.20 283 8,264 1150974 -.458 .324 .324 43.27 191 8,264 752391 -1.117 .132 .132

8 47.03 31 1,458 23820 .521 .699 .301 60.75 24 1,458 18210 .346 .635 .365

9 35.28 82 2,893 109801 -1.165 .122 .122 53.57 54 2,893 73522 -.748 .227 .227

10 21.40 10 214 934 -.696 .243 .243 23.78 9 214 898 -.351 .363 .363

11 38.49 159 6,120 528232 1.872 .969 .031 49.36 124 6,120 414674 1.791 .963 .037

12 31.71 1,122 35,581 20143403 .530 .702 .298 48.54 733 35,581 13456244 1.495 .933 .067

13 24.24 619 15,005 4914642 2.511 .994 .006 36.51 411 15,005 3222921 1.587 .944 .056

14 34.56 867 29,966 13233500 .955 .830 .170 49.04 611 29,966 9655906 2.344 .990 .010

15 43.82 39 1,709 29539 -1.229 .110 .110 63.30 27 1,709 20357 -1.059 .145 .145

16 41.00 3 123 65 -1.943 .026 .026 61.50 2 123 47 -1.514 .065 .065

17 123.00 1 123 65 .099 .539 .461 -- -- -- -- -- -- --

18 66.84 412 27,539 5702876 .185 .573 .427 110.60 249 27,539 3543901 .919 .821 .179

19 18.27 1,053 19,240 10664329 2.966 .998 .002 27.06 711 19,240 7255350 2.806 .997 .003

20 22.34 274 6,122 843730 .172 .568 .432 30.31 202 6,122 593462 -.990 .161 .161

21 21.03 251 5,279 647771 -.611 .271 .271 32.99 160 5,279 408608 -.711 .239 .239

22 17.25 2,003 34,541 34900898 .690 .755 .245 23.87 1,447 34,541 25309464 .841 .800 .200

23 26.38 45 1,187 28275 .682 .752 .248 38.29 31 1,187 17659 -.388 .349 .349

24 49.61 397 19,693 3944886 .316 .624 .376 84.16 234 19,693 2278020 -.300 .382 .382

25 50.95 270 13,756 1746381 -1.696 .045 .045 72.40 190 13,756 1241939 -1.185 .118 .118

26 16.33 1,905 31,099 29882011 .664 .747 .253 22.18 1,402 31,099 21974171 .517 .697 .303

27 19.95 1,042 20,787 10490866 -1.751 .040 .040 27.72 750 20,787 7477228 -1.934 .027 .027

28 25.10 479 12,022 3002141 1.618 .947 .053 38.66 311 12,022 2025405 2.549 .995 .005

29 64.83 245 15,884 1872784 -1.017 .155 .155 101.82 156 15,884 1161097 -1.359 .087 .087

30 16.61 1,904 31,631 31437517 3.325 1.000 0 22.43 1,410 31,631 23414945 3.252 .999 .001

31 21.11 859 18,129 8024998 1.556 .940 .060 30.07 603 18,129 5659170 1.504 .934 .066

32 31.06 536 16,648 4334756 -1.141 .127 .127 45.49 366 16,648 2978856 -.737 .231 .231

33 28.10 825 23,183 9673148 .573 .717 .283 42.00 552 23,183 6534766 .867 .807 .193

34 21.18 171 3,622 321822 .888 .813 .187 35.86 101 3,622 184604 .161 .564 .436

35 28.91 356 10,292 1973949 2.533 .994 .006 39.89 258 10,292 1445751 2.474 .993 .007

36 23.18 478 11,081 2556998 -1.306 .096 .096 30.28 366 11,081 1934485 -1.525 .064 .064

37 23.62 462 10,911 2553236 .484 .686 .314 34.31 318 10,911 1764488 .528 .701 .299

38 28.77 779 22,410 9241429 2.840 .998 .002 44.38 505 22,410 5878191 1.511 .935 .065

39 21.61 904 19,535 9256678 2.518 .994 .006 31.41 622 19,535 6377995 2.152 .984 .016

40 32.13 323 10,379 1752800 1.422 .923 .077 45.93 226 10,379 1230876 1.289 .901 .099

41 19.25 1,288 24,787 16300241 1.314 .906 .094 28.20 879 24,787 11203741 1.461 .928 .072

42 37.20 20 744 6755 -.713 .238 .238 53.14 14 744 5243 .044 .517 .483

43 38.06 843 32,082 13449045 -.273 .392 .392 57.50 558 32,082 8800541 -.687 .246 .246

44 19.88 989 19,656 10148703 2.403 .992 .008 27.72 709 19,656 7288384 2.120 .983 .017

45 16.96 1,117 18,947 11075906 2.702 .997 .003 23.33 812 18,947 8245983 3.551 1.000 0

46 26.01 994 25,853 12721692 -.541 .294 .294 37.41 691 25,853 8810086 -.623 .267 .267

47 28.41 224 6,363 764381 1.882 .970 .030 42.42 150 6,363 528453 2.277 .989 .011

48 28.24 200 5,648 601364 1.586 .944 .056 41.23 137 5,648 425808 2.039 .979 .021

Table 5 Table 5. Summary of interoccurrence intervals for daily precipitation thresholds of 0.75 and 1.0 inch

[--, not available, no events that equal or exceed the threshold were observed]
Table 5 117

49 15.10 20 302 3540 1.334 .909 .091 27.46 11 302 1775 0.394 .653 .347

50 24.73 37 915 19784 1.778 .962 .038 45.75 20 915 11406 1.910 .972 .028

51 25.96 702 18,223 6380688 -.112 .455 .455 35.66 511 18,223 4610113 -.386 .350 .350

52 20.58 637 13,109 4192991 .186 .574 .426 30.28 433 13,109 2766926 -.904 .183 .183

53 12.75 24 306 3616 -.129 .448 .448 18.00 17 306 2969 1.010 .844 .156

54 29.00 3 87 96 -.793 .214 .214 29.00 3 87 96 -.793 .214 .214

55 32.13 307 9,865 1482908 -.629 .265 .265 44.84 220 9,865 1067504 -.418 .338 .338

56 39.75 60 2,385 70580 -.182 .428 .428 72.27 33 2,385 34616 -1.198 .116 .116

57 72.25 271 19,579 2777083 1.334 .909 .091 117.95 166 19,579 1800859 2.414 .992 .008

58 40.53 15 608 3295 -1.861 .031 .031 50.67 12 608 2559 -1.791 .037 .037

59 36.74 986 36,226 17905266 .140 .556 .444 54.48 665 36,226 11882118 -.605 .273 .273

60 140.00 3 420 527 -.491 .312 .312 420.00 1 420 339 1.064 .856 .144

61 86.81 321 27,865 4661655 1.314 .905 .095 146.66 190 27,865 2743441 .868 .807 .193

62 43.60 5 218 701 1.109 .866 .134 109.00 2 218 304 .966 .833 .167

63 52.28 39 2,039 44242 1.219 .889 .111 81.56 25 2,039 27321 .623 .733 .267

64 -- -- -- -- -- -- -- -- -- -- -- -- -- --

65 27.09 274 7,422 1025613 .248 .598 .402 37.87 196 7,422 726917 -.015 .494 .494

66 27.79 84 2,334 88293 -1.577 .057 .057 36.47 64 2,334 65242 -1.753 .040 .040

67 21.98 607 13,340 4192949 1.521 .936 .064 32.94 405 13,340 2801767 1.296 .902 .098

68 63.10 83 5,237 224905 .550 .709 .291 104.74 50 5,237 139837 .834 .798 .202

69 86.26 57 4,917 145693 .519 .698 .302 144.62 34 4,917 83246 -.041 .483 .483

70 25.27 41 1,036 26910 2.962 .998 .002 34.53 30 1,036 20035 2.744 .997 .003

71 27.21 28 762 10233 -.374 .354 .354 40.11 19 762 6758 -.502 .308 .308

72 34.38 127 4,366 286151 .627 .735 .265 50.18 87 4,366 193643 .317 .624 .376

73 34.73 360 12,503 2313199 .915 .820 .180 48.65 257 12,503 1707227 1.739 .959 .041

74 25.17 48 1,208 31087 .867 .807 .193 35.53 34 1,208 22527 .979 .836 .164

75 19.24 1,218 23,435 15081105 3.427 1.000 0 25.95 903 23,435 11392532 3.993 1.000 0

76 57.70 20 1,154 11509 -.021 .492 .492 96.17 12 1,154 7085 .140 .556 .444

77 15.81 1,002 15,838 8066916 .913 .819 .181 20.98 755 15,838 6105921 1.012 .844 .156

78 32.91 22 724 7595 -.376 .353 .353 45.25 16 724 5369 -.506 .306 .306

79 20.82 28 583 9834 1.878 .970 .030 30.68 19 583 6881 1.830 .966 .034

80 15.47 2,301 35,599 42448046 3.025 .999 .001 21.39 1,664 35,599 30579926 2.294 .989 .011

81 15.51 911 14,126 6698981 2.150 .984 .016 21.57 655 14,126 4856381 2.205 .986 .014

82 18.34 691 12,671 4448061 .730 .767 .233 23.60 537 12,671 3488710 1.021 .846 .154

83 29.61 1,204 35,650 21613219 .425 .665 .335 42.34 842 35,650 15310488 1.011 .844 .156

84 19.29 405 7,812 1608603 .588 .722 .278 26.13 299 7,812 1165131 -.071 .472 .472

85 20.69 80 1,655 66921 .169 .567 .433 27.58 60 1,655 51787 .578 .718 .282

86 25.00 578 14,452 4461186 2.837 .998 .002 36.40 397 14,452 3010978 1.711 .956 .044

87 37.91 32 1,213 18157 -.632 .264 .264 50.54 24 1,213 14164 -.229 .410 .410

88 33.65 382 12,853 2467741 .177 .570 .430 46.07 279 12,853 1881674 1.431 .924 .076

89 25.91 736 19,069 7303011 1.913 .972 .028 39.32 485 19,069 4835973 1.747 .960 .040

90 32.12 199 6,392 618410 -.676 .250 .250 50.33 127 6,392 420634 .709 .761 .239

91 36.72 338 12,411 2000528 -1.472 .071 .071 57.73 215 12,411 1287022 -.898 .185 .185

92 25.07 494 12,385 3169387 1.388 .917 .083 35.90 345 12,385 2193436 .859 .805 .195

93 15.17 140 2,124 151358 .369 .644 .356 19.67 108 2,124 116361 .261 .603 .397

94 78.58 31 2,436 34152 -.921 .179 .179 187.39 13 2,436 16300 .184 .573 .427

95 36.93 28 1,034 11619 -1.809 .035 .035 54.42 19 1,034 8012 -1.392 .082 .082

96 48.26 286 13,801 1938551 -.519 .302 .302 74.20 186 13,801 1260498 -.423 .336 .336

97 75.27 15 1,129 6151 -1.835 .033 .033 102.64 11 1,129 4729 -1.370 .085 .085

98 50.52 377 19,044 3845520 2.396 .992 .008 74.39 256 19,044 2617430 2.044 .980 .020

99 28.50 4 114 156 -1.094 .137 .137 38.00 3 114 148 -.404 .343 .343

100 39.26 728 28,580 10944880 2.434 .993 .007 55.28 517 28,580 7903819 2.750 .997 .003

Table 5. Summary of interoccurrence intervals for daily precipitation thresholds of 0.75 and 1.0 inch—Continued

Seq.

no.

Daily precipitation threshold of 0.75 inch and greater Daily precipitation threshold of 1.0 inch and greater

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue
118 Atlas of Interoccurrence Intervals for Selected Thresholds of Daily Precipitation in Texas 

101 32.78 281 9,211 1254807 -0.883 .189 .189 44.93 205 9,211 883272 -1.599 .055 .055

102 24.72 32 791 14199 1.195 .884 .116 30.42 26 791 10752 .403 .656 .344

103 25.90 1,446 37,448 27896360 1.998 .977 .023 38.25 979 37,448 19349503 3.012 .999 .001

104 30.32 207 6,276 693950 1.703 .956 .044 45.15 139 6,276 464542 1.328 .908 .092

105 37.67 272 10,246 1347592 -.940 .174 .174 50.72 202 10,246 1023732 -.264 .396 .396

106 47.49 75 3,562 110515 -2.590 .005 .005 80.96 44 3,562 67480 -1.596 .055 .055

107 22.42 334 7,487 1281725 .795 .787 .213 30.44 246 7,487 946678 .760 .776 .224

108 25.79 1,448 37,342 27643807 1.483 .931 .069 36.83 1,014 37,342 19139044 .602 .726 .274

109 14.59 988 14,412 7329318 1.604 .946 .054 20.44 705 14,412 5227872 1.337 .909 .091

110 19.39 1,790 34,710 32348723 3.027 .999 .001 27.46 1,264 34,710 22652374 2.009 .978 .022

111 29.86 42 1,254 28472 .911 .819 .181 50.16 25 1,254 15566 -.060 .476 .476

112 43.31 530 22,955 5949267 -.877 .190 .190 71.07 323 22,955 3730114 .192 .576 .424

113 40.76 59 2,405 59770 -2.096 .018 .018 77.58 31 2,405 36089 -.308 .379 .379

114 54.22 37 2,006 42268 1.464 .928 .072 111.44 18 2,006 19042 .402 .656 .344

115 123.71 146 18,062 1365879 .752 .774 .226 240.83 75 18,062 738307 1.351 .912 .088

116 49.20 118 5,805 354698 .670 .749 .251 73.48 79 5,805 241625 .828 .796 .204

117 44.58 431 19,214 4277397 1.188 .883 .118 73.06 263 19,214 2537355 .119 .547 .453

118 45.96 22 1,011 11459 .247 .598 .402 59.47 17 1,011 8352 -.201 .420 .420

119 26.32 1,048 27,586 15253953 3.099 .999 .001 38.21 722 27,586 10646424 3.215 .999 .001

120 16.42 1,168 19,175 11639799 2.334 .990 .010 22.91 837 19,175 8394900 2.312 .990 .010

121 24.35 754 18,359 7443885 3.591 1.000 0 35.86 512 18,359 5186240 4.056 1.000 0

122 46.22 187 8,643 824133 .469 .681 .319 68.06 127 8,643 566031 .612 .730 .270

123 38.22 903 34,510 15891790 1.037 .850 .150 53.34 647 34,510 11438954 1.085 .861 .139

124 35.12 215 7,550 830836 .601 .726 .274 45.21 167 7,550 616097 -.509 .306 .306

125 34.19 694 23,727 8529918 1.644 .950 .050 50.38 471 23,727 5743426 1.048 .853 .147

126 19.46 186 3,619 353174 1.166 .878 .122 27.84 130 3,619 235077 -.013 .495 .495

127 56.35 344 19,385 3265114 -.666 .253 .253 91.01 213 19,385 1977936 -1.060 .145 .145

128 17.42 625 10,885 3451819 .640 .739 .261 23.06 472 10,885 2589015 .295 .616 .384

129 26.53 740 19,634 7436364 1.114 .867 .133 40.57 484 19,634 4917611 1.333 .909 .091

130 32.61 808 26,350 10922421 1.281 .900 .100 47.82 551 26,350 7477177 1.220 .889 .111

131 31.71 24 761 9546 .385 .650 .350 42.28 18 761 6779 -.075 .470 .470

132 21.54 652 14,041 4755950 1.726 .958 .042 31.70 443 14,041 3201049 1.066 .857 .143

133 21.27 1,707 36,302 31674693 1.596 .945 .055 29.39 1,235 36,302 22920540 1.369 .914 .086

134 32.49 37 1,202 18344 -1.845 .033 .033 38.77 31 1,202 15019 -1.870 .031 .031

135 33.78 36 1,216 22352 .220 .587 .413 55.27 22 1,216 14318 .572 .716 .284

136 26.42 1,174 31,019 18483631 .898 .815 .185 39.67 782 31,019 12767654 2.553 .995 .005

137 26.56 133 3,532 246419 .982 .837 .163 40.14 88 3,532 168710 1.391 .918 .082

138 32.27 237 7,647 986463 2.363 .991 .009 46.91 163 7,647 678563 1.963 .975 .025

139 143.00 1 143 105 .812 .791 .209 -- -- -- -- -- -- --

140 21.50 60 1,290 39077 .131 .552 .448 29.32 44 1,290 28815 .176 .570 .430

141 16.39 651 10,670 3519164 .586 .721 .279 24.25 440 10,670 2346493 -.014 .494 .494

142 15.09 532 8,028 2204335 1.289 .901 .099 20.53 391 8,028 1630846 1.339 .910 .090

143 15.68 1,146 17,968 10398759 .587 .721 .279 22.38 803 17,968 7275692 .419 .662 .338

144 49.35 279 13,768 1809796 -1.670 .048 .048 75.65 182 13,768 1126366 -2.360 .009 .009

145 52.78 331 17,470 2888294 -.033 .487 .487 76.29 229 17,470 1988337 -.157 .438 .438

146 38.09 744 28,335 10833897 1.315 .906 .094 53.26 532 28,335 7720978 .975 .835 .165

147 30.22 643 19,432 6630128 2.691 .996 .004 44.88 433 19,432 4599240 3.360 1.000 0

148 52.79 24 1,267 16020 .455 .676 .324 97.46 13 1,267 8304 .052 .521 .479

149 23.78 9 214 1127 .885 .812 .188 23.78 9 214 1127 .885 .812 .188

150 27.52 42 1,156 24894 .286 .613 .387 38.53 30 1,156 17385 .025 .510 .490

151 35.09 200 7,017 683327 -.641 .261 .261 50.85 138 7,017 468234 -.670 .252 .252

152 80.67 98 7,906 368358 -.843 .200 .200 127.52 62 7,906 235480 -.535 .297 .297

Table 5. Summary of interoccurrence intervals for daily precipitation thresholds of 0.75 and 1.0 inch—Continued

Seq.

no.

Daily precipitation threshold of 0.75 inch and greater Daily precipitation threshold of 1.0 inch and greater

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue
Table 5 119

153 19.82 731 14,486 5525248 2.040 .979 .021 27.44 528 14,486 4103452 2.905 .998 .002

154 45.08 237 10,685 1194343 -1.513 .065 .065 72.20 148 10,685 719615 -1.894 .029 .029

155 24.58 897 22,051 9883796 -.032 .487 .487 35.51 621 22,051 7026580 1.133 .871 .129

156 66.26 222 14,709 1638658 .094 .538 .462 122.58 120 14,709 836275 -.995 .160 .160

157 63.50 2 127 132 .096 .538 .462 -- -- -- -- -- -- --

158 30.40 67 2,037 59015 -1.917 .028 .028 65.71 31 2,037 25686 -1.798 .036 .036

159 28.80 611 17,595 5439143 .509 .694 .306 42.92 410 17,595 3672502 .637 .738 .262

160 22.66 264 5,981 791067 .056 .522 .478 34.37 174 5,981 518903 -.063 .475 .475

161 25.88 521 13,484 3506179 -.072 .471 .471 38.31 352 13,484 2312386 -.833 .203 .203

162 26.76 367 9,819 1932838 2.413 .992 .008 37.91 259 9,819 1373263 2.230 .987 .013

163 27.61 1,247 34,426 22708965 3.546 1.000 0 39.34 875 34,426 15924216 2.935 .998 .002

164 27.26 19 518 5137 .331 .630 .370 37.00 14 518 3626 0 .500 .500

165 35.91 33 1,185 18761 -.403 .344 .344 53.86 22 1,185 12472 -.351 .363 .363

166 30.01 211 6,331 685374 .657 .744 .256 40.07 158 6,331 518275 .789 .785 .215

167 34.49 35 1,207 18556 -1.245 .107 .107 54.86 22 1,207 11877 -.857 .196 .196

168 20.43 690 14,097 4899962 .341 .634 .366 29.99 470 14,097 3280606 -.365 .358 .358

169 24.82 49 1,216 32279 1.012 .844 .156 36.85 33 1,216 19247 -.405 .343 .343

170 39.77 153 6,084 476839 .525 .700 .300 64.04 95 6,084 293760 .279 .610 .390

171 34.74 237 8,233 976559 .026 .510 .490 52.44 157 8,233 652731 .216 .586 .414

172 23.97 1,370 32,834 22876958 1.099 .864 .136 35.15 934 32,834 15468144 .465 .679 .321

173 44.96 44 1,978 41009 -.662 .254 .254 54.94 36 1,978 33919 -.492 .311 .311

174 35.72 173 6,180 568933 1.464 .928 .072 51.93 119 6,180 377970 .527 .701 .299

175 22.40 62 1,389 47916 1.538 .938 .062 31.57 44 1,389 36025 2.056 .980 .020

176 33.25 603 20,049 6212491 1.180 .881 .119 47.17 425 20,049 4394766 1.126 .870 .130

177 40.67 790 32,125 12686451 -.011 .496 .496 61.78 520 32,125 8203217 -.706 .240 .240

178 30.09 11 331 1538 -.891 .186 .186 41.38 8 331 1202 -.451 .326 .326

179 106.92 182 19,460 1956464 2.449 .993 .007 178.53 109 19,460 1170290 1.871 .969 .031

180 18.50 901 16,672 7754751 1.689 .954 .046 26.26 635 16,672 5333639 .332 .630 .370

181 47.14 599 28,238 8366593 -.455 .325 .325 75.71 373 28,238 5372059 .671 .749 .251

182 25.33 550 13,932 3836822 .059 .523 .477 36.57 381 13,932 2623913 -.384 .351 .351

183 23.02 84 1,934 84612 .661 .746 .254 36.49 53 1,934 55358 1.011 .844 .156

184 16.32 53 865 23548 .344 .635 .365 19.66 44 865 19480 .272 .607 .393

185 62.97 35 2,204 35475 -.822 .206 .206 100.18 22 2,204 22664 -.529 .298 .298

186 33.12 69 2,285 78377 -.083 .467 .467 40.80 56 2,285 67341 .681 .752 .248

187 15.25 4 61 122 0 .500 .500 30.50 2 61 63 .080 .532 .468

188 29.06 510 14,820 3744959 -.353 .362 .362 42.34 350 14,820 2650953 .718 .763 .237

189 43.02 614 26,415 8060020 -.261 .397 .397 61.86 427 26,415 5549472 -.572 .284 .284

190 22.54 839 18,911 8320703 2.451 .993 .007 31.47 601 18,911 5894721 1.584 .943 .057

191 38.04 337 12,819 2238277 1.152 .875 .125 52.75 243 12,819 1605844 .838 .799 .201

192 16.00 1,136 18,176 10818202 2.795 .997 .003 22.44 810 18,176 7878114 3.461 1.000 0

193 45.90 265 12,164 1851240 4.190 1.000 0 78.48 155 12,164 1068225 2.871 .998 .002

194 28.70 224 6,429 697861 -.799 .212 .212 39.93 161 6,429 516710 -.035 .486 .486

195 121.62 78 9,486 352836 -.708 .240 .240 225.86 42 9,486 184569 -.825 .205 .205

196 42.48 339 14,400 2476327 .464 .679 .321 64.29 224 14,400 1646616 .544 .707 .293

197 21.47 377 8,095 1618569 2.042 .979 .021 29.22 277 8,095 1190239 1.776 .962 .038

198 21.36 593 12,665 3827926 .817 .793 .207 31.20 406 12,665 2720115 2.024 .979 .021

199 15.79 1,446 22,827 16494786 -.037 .485 .485 22.06 1,035 22,827 11975702 .768 .779 .221

200 28.88 489 14,121 3585921 1.479 .930 .070 44.13 320 14,121 2330142 .971 .834 .166

201 20.02 1,146 22,939 13503066 1.602 .945 .055 27.84 824 22,939 9880966 2.263 .988 .012

202 23.14 21 486 5873 1.198 .884 .116 34.71 14 486 3749 .661 .746 .254

203 25.62 550 14,090 4016226 1.483 .931 .069 38.50 366 14,090 2693176 1.474 .930 .070

204 13.48 103 1,388 71578 .024 .509 .491 18.76 74 1,388 51129 -.066 .474 .474

Table 5. Summary of interoccurrence intervals for daily precipitation thresholds of 0.75 and 1.0 inch—Continued

Seq.

no.

Daily precipitation threshold of 0.75 inch and greater Daily precipitation threshold of 1.0 inch and greater

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue
120 Atlas of Interoccurrence Intervals for Selected Thresholds of Daily Precipitation in Texas 

205 128.00 3 384 509 -0.349 .364 .364 192.00 2 384 333 -0.325 .372 .372

206 44.32 66 2,925 84691 -1.725 .042 .042 86.03 34 2,925 42292 -1.510 .066 .066

207 39.69 13 516 3118 -.439 .330 .330 73.71 7 516 1692 -.289 .386 .386

208 45.77 180 8,239 807911 2.081 .981 .019 71.64 115 8,239 543104 2.720 .997 .003

209 27.90 548 15,291 4170015 -.191 .424 .424 39.61 386 15,291 3042089 1.049 .853 .147

210 33.80 127 4,292 289100 1.186 .882 .118 49.91 86 4,292 187637 .268 .606 .394

211 32.90 62 2,040 58585 -1.004 .158 .158 51.00 40 2,040 41414 .165 .566 .434

212 34.96 410 14,334 2901243 -.444 .328 .328 49.09 292 14,334 2065778 -.382 .351 .351

213 23.33 136 3,173 232555 1.572 .942 .058 32.71 97 3,173 162731 .980 .836 .164

214 41.50 28 1,162 14589 -.946 .172 .172 61.16 19 1,162 10772 -.183 .428 .428

215 33.38 24 801 9435 -.156 .438 .438 61.62 13 801 5903 .835 .798 .202

216 35.28 43 1,517 30905 -.596 .276 .276 54.18 28 1,517 22143 .391 .652 .348

217 35.23 430 15,148 3184004 -.803 .211 .211 51.70 293 15,148 2128580 -1.210 .113 .113

218 45.01 411 18,497 4001427 1.850 .968 .032 72.25 256 18,497 2446908 .928 .823 .177

219 -- -- -- -- -- -- -- -- -- -- -- -- -- --

220 35.87 683 24,501 8190214 -.957 .169 .169 54.21 452 24,501 5187302 -2.327 .010 .010

221 14.04 336 4,717 801365 .357 .639 .361 18.64 253 4,717 628624 1.474 .930 .070

222 56.01 353 19,773 3763159 2.548 .995 .005 97.40 203 19,773 2124848 1.450 .926 .074

223 37.84 172 6,509 567978 .333 .630 .370 53.35 122 6,509 395660 -.067 .473 .473

224 45.99 133 6,117 403395 -.166 .434 .434 81.56 75 6,117 217131 -.802 .211 .211

225 27.91 424 11,834 2682641 2.471 .993 .007 34.70 341 11,834 2090509 1.154 .876 .124

226 40.69 822 33,447 13558696 -.679 .249 .249 62.29 537 33,447 8609652 -1.658 .049 .049

227 17.14 70 1,200 45274 1.130 .871 .129 24.49 49 1,200 32357 1.219 .889 .111

228 16.97 2,006 34,037 34163435 .055 .522 .478 23.60 1,442 34,037 24567134 .071 .528 .472

229 29.48 309 9,110 1506593 2.144 .984 .016 42.37 215 9,110 1067417 2.285 .989 .011

230 37.79 847 32,007 13389170 -.617 .269 .269 57.77 554 32,007 8471987 -1.812 .035 .035

231 24.75 1,337 33,090 22250397 .371 .645 .355 35.43 934 33,090 15545690 .317 .625 .375

232 20.81 120 2,497 151862 .259 .602 .398 30.45 82 2,497 108770 .979 .836 .164

233 15.88 1,088 17,281 9756868 2.164 .985 .015 21.85 791 17,281 7014677 1.283 .900 .100

234 21.12 49 1,035 24507 -.407 .342 .342 38.33 27 1,035 11576 -1.544 .061 .061

235 24.84 941 23,374 10573000 -2.051 .020 .020 36.93 633 23,374 7048168 -2.060 .020 .020

236 38.03 151 5,743 405285 -1.390 .082 .082 50.38 114 5,743 311246 -.910 .182 .182

237 17.97 1,034 18,579 10290330 3.972 1.000 0 24.45 760 18,579 7329926 1.826 .966 .034

238 34.91 122 4,259 236171 -1.740 .041 .041 52.58 81 4,259 174476 .180 .571 .429

239 17.61 984 17,330 9020415 3.148 .999 .001 24.72 701 17,330 6360491 2.162 .985 .015

240 60.97 214 13,047 1417960 .398 .655 .345 111.51 117 13,047 765577 .057 .523 .477

241 30.59 1,223 37,406 22751455 -.324 .373 .373 44.85 834 37,406 15839033 .772 .780 .220

242 20.88 839 17,517 7530962 1.247 .894 .106 30.10 582 17,517 5088157 -.076 .470 .470

243 22.19 932 20,679 9501051 -.743 .229 .229 32.46 637 20,679 6394465 -1.273 .102 .102

244 18.40 5 92 154 -1.280 .100 .100 18.40 5 92 154 -1.280 .100 .100

245 43.25 610 26,383 7761323 -1.518 .065 .065 63.88 413 26,383 5094793 -2.283 .011 .011

246 19.95 1,004 20,030 10705029 3.548 1.000 0 27.51 728 20,030 7827685 3.441 1.000 0

247 27.60 1,106 30,526 17294155 1.410 .921 .079 43.30 705 30,526 11139169 1.619 .947 .053

248 25.97 76 1,974 75667 .132 .552 .448 34.63 57 1,974 57416 .269 .606 .394

249 18.50 163 3,015 260636 1.342 .910 .090 23.56 128 3,015 201090 .826 .795 .205

250 54.63 136 7,429 460476 -1.787 .037 .037 80.75 92 7,429 320582 -1.028 .152 .152

251 120.50 2 241 165 -.773 .220 .220 -- -- -- -- -- -- --

252 49.43 47 2,323 50009 -.997 .160 .160 70.39 33 2,323 34520 -.989 .161 .161

253 37.84 37 1,400 29497 1.463 .928 .072 50.00 28 1,400 24062 2.087 .982 .018

254 53.68 363 19,485 3611287 .698 .757 .243 89.38 218 19,485 2212720 1.070 .858 .142

255 18.14 1,066 19,333 10771117 2.561 .995 .005 24.85 778 19,333 7958402 2.813 .998 .002

256 17.07 1,067 18,213 10198824 2.808 .998 .002 24.32 749 18,213 7262480 3.070 .999 .001

Table 5. Summary of interoccurrence intervals for daily precipitation thresholds of 0.75 and 1.0 inch—Continued

Seq.

no.

Daily precipitation threshold of 0.75 inch and greater Daily precipitation threshold of 1.0 inch and greater

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue
Table 5 121

257 202.67 3 608 803 -0359 .360 .360 202.67 3 608 803 -0.359 .360 .360

258 50.56 385 19,465 3869214 1.108 .866 .134 78.49 248 19,465 2610376 2.223 .987 .013

259 28.07 161 4,519 321096 -2.579 .005 .005 44.74 101 4,519 202781 -1.940 .026 .026

260 24.93 885 22,062 9570882 -1.011 .156 .156 35.58 620 22,062 6842022 .018 .507 .493

261 28.65 51 1,461 35621 -.543 .294 .294 42.97 34 1,461 23146 -.688 .246 .246

262 23.72 283 6,712 929823 -.611 .271 .271 31.96 210 6,712 696125 -.308 .379 .379

263 122.77 151 18,538 1559730 2.435 .993 .007 226.07 82 18,538 874095 2.353 .991 .009

264 32.25 369 11,901 2416640 3.347 1.000 0 44.41 268 11,901 1753392 2.821 .998 .002

265 31.01 636 19,723 6577974 2.132 .983 .017 42.88 460 19,723 4811537 2.254 .988 .012

266 13.68 242 3,310 399511 -.067 .473 .473 18.60 178 3,310 289296 -.415 .339 .339

267 21.96 1,658 36,415 30338883 .352 .638 .362 31.39 1,160 36,415 21509566 1.086 .861 .139

268 20.18 181 3,653 336695 .430 .666 .334 29.70 123 3,653 236091 .977 .836 .164

269 23.63 30 709 11934 1.159 .877 .123 35.45 20 709 8674 1.731 .958 .042

270 27.12 522 14,154 3751926 .618 .732 .268 38.36 369 14,154 2663116 .659 .745 .255

271 -- -- -- -- -- -- -- -- -- -- -- -- -- --

272 -- -- -- -- -- -- -- -- -- -- -- -- -- --

273 40.01 794 31,770 12560740 -.201 .420 .420 55.93 568 31,770 8982155 -.185 .426 .426

274 43.28 263 11,383 1646467 2.807 .998 .003 57.20 199 11,383 1248542 2.501 .994 .006

275 36.97 65 2,403 74198 -.697 .243 .243 42.91 56 2,403 64077 -.618 .268 .268

276 41.66 155 6,457 492516 -.341 .367 .367 67.97 95 6,457 303153 -.196 .422 .422

277 23.85 47 1,121 28457 .953 .830 .170 33.97 33 1,121 19449 .512 .696 .304

278 21.49 551 11,840 3292423 .380 .648 .352 31.49 376 11,840 2192244 -.508 .306 .306

279 365.50 2 731 449 -.945 .172 .172 365.50 2 731 449 -.945 .172 .172

280 68.40 241 16,485 2095962 1.483 .931 .069 111.39 148 16,485 1273652 .929 .823 .177

281 26.44 167 4,415 398495 1.812 .965 .035 38.73 114 4,415 265818 1.041 .851 .149

282 23.12 58 1,341 38818 -.024 .490 .490 34.39 39 1,341 28041 .782 .783 .217

283 25.25 769 19,415 7575233 .709 .761 .239 39.79 488 19,415 4772123 .282 .611 .389

284 34.18 279 9,535 1359736 .644 .740 .260 50.45 189 9,535 981989 2.139 .984 .016

285 18.03 1,805 32,536 29195740 -.421 .337 .337 24.01 1,355 32,536 21206112 -2.421 .008 .008

286 41.20 907 37,369 16619580 -1.007 .157 .157 63.34 590 37,369 10769344 -.971 .166 .166

287 44.54 41 1,826 36508 -.274 .392 .392 62.97 29 1,826 25813 -.234 .407 .407

288 28.97 455 13,182 3056487 .709 .761 .239 42.25 312 13,182 1987641 -1.023 .153 .153

289 39.10 29 1,134 13393 -1.730 .042 .042 59.68 19 1,134 7386 -2.374 .009 .009

290 31.72 962 30,511 14691629 .058 .523 .477 46.16 661 30,511 10064198 -.087 .465 .465

291 43.36 450 19,511 4398844 .074 .530 .470 65.69 297 19,511 2884179 -.136 .446 .446

292 28.09 78 2,191 85284 -.030 .488 .488 38.44 57 2,191 61458 -.206 .418 .418

293 25.21 1,401 35,323 25002283 .677 .751 .249 34.77 1,016 35,323 18548346 1.859 .968 .032

294 17.14 1,099 18,834 10550431 1.116 .868 .132 22.50 837 18,834 8064310 1.159 .877 .123

295 28.81 206 5,935 636007 1.005 .842 .158 41.80 142 5,935 441014 .961 .832 .168

296 18.02 954 17,191 8485662 1.863 .969 .031 25.10 685 17,191 6028516 1.083 .860 .140

297 16.94 1,154 19,546 11713827 2.274 .989 .012 23.84 820 19,546 8292648 1.725 .958 .042

298 22.83 448 10,227 2351736 .974 .835 .165 35.63 287 10,227 1508334 .815 .792 .208

299 77.67 3 233 272 -.665 .253 .253 116.50 2 233 136 -1.020 .154 .154

300 55.19 88 4,857 213723 .001 .500 .500 105.59 46 4,857 118162 .678 .751 .249

301 53.56 315 16,871 2582375 -.865 .193 .193 88.33 191 16,871 1556581 -.811 .209 .209

302 56.29 343 19,309 3506228 1.886 .970 .030 91.51 211 19,309 2243834 2.553 .995 .005

303 14.76 33 487 7629 -.503 .307 .307 17.39 28 487 5816 -1.347 .089 .089

304 23.24 1,078 25,051 13847506 1.453 .927 .073 33.49 748 25,051 9749664 1.924 .973 .027

305 21.00 74 1,554 50437 -1.830 .034 .034 28.78 54 1,554 39449 -.761 .223 .223

306 20.44 1,820 37,205 34021584 .360 .641 .359 28.21 1,319 37,205 24771550 .602 .726 .274

307 40.71 519 21,126 5827471 2.485 .994 .006 66.43 318 21,126 3636380 2.550 .995 .005

308 20.57 864 17,772 7711403 .225 .589 .411 27.34 650 17,772 5745663 -.231 .409 .409

Table 5. Summary of interoccurrence intervals for daily precipitation thresholds of 0.75 and 1.0 inch—Continued

Seq.

no.

Daily precipitation threshold of 0.75 inch and greater Daily precipitation threshold of 1.0 inch and greater

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue
122 Atlas of Interoccurrence Intervals for Selected Thresholds of Daily Precipitation in Texas 

309 40.24 29 1,167 19423 1.379 .916 .084 53.05 22 1,167 15105 1.435 .924 .076

310 26.52 117 3,103 159373 -2.286 .011 .011 37.39 83 3,103 114346 -1.768 .039 .039

311 46.39 82 3,804 161205 .527 .701 .299 62.36 61 3,804 114167 -.216 .414 .414

312 22.99 806 18,527 8038207 3.766 1.000 0 36.05 514 18,527 5182727 3.474 1.000 0

313 28.66 86 2,465 105532 -.070 .472 .472 42.50 58 2,465 69642 -.340 .367 .367

314 21.34 53 1,131 31831 .782 .783 .217 31.42 36 1,131 22573 1.131 .871 .129

315 15.74 1,187 18,684 11544875 2.454 .993 .007 22.46 832 18,684 8215903 2.850 .998 .002

316 52.08 38 1,979 34686 -.828 .204 .204 82.46 24 1,979 22782 -.345 .365 .365

317 90.39 18 1,627 13441 -.603 .273 .273 125.15 13 1,627 10768 .114 .545 .455

318 52.38 315 16,498 2685993 1.036 .850 .150 76.38 216 16,498 1855739 1.057 .855 .145

319 43.98 85 3,738 165895 .707 .760 .240 69.22 54 3,738 105536 .581 .719 .281

320 138.21 58 8,016 246321 .786 .784 .216 308.31 26 8,016 113553 .792 .786 .214

321 21.35 971 20,733 10414057 1.867 .969 .031 30.58 678 20,733 7311360 1.815 .965 .035

322 22.15 566 12,538 3637858 1.041 .851 .149 28.18 445 12,538 2897912 1.417 .922 .078

323 26.17 205 5,364 566418 .749 .773 .227 36.49 147 5,364 402292 .428 .666 .334

324 24.01 1,316 31,602 21465786 2.030 .979 .021 35.91 880 31,602 14395457 1.813 .965 .035

325 56.79 75 4,259 142660 -1.602 .055 .055 85.18 50 4,259 90809 -1.802 .036 .036

326 15.83 410 6,492 1324655 -.164 .435 .435 21.71 299 6,492 974450 .120 .548 .452

327 33.44 243 8,126 982818 -.123 .451 .451 45.65 178 8,126 707274 -.509 .305 .305

328 29.55 33 975 15795 -.181 .428 .428 36.11 27 975 13398 .161 .564 .436

329 15.10 766 11,566 4545608 1.254 .895 .105 20.88 554 11,566 3267450 .810 .791 .209

330 17.62 2,073 36,526 37723414 -.283 .389 .389 25.09 1,456 36,526 26500049 -.226 .411 .411

331 39.87 168 6,698 551821 -.431 .333 .333 61.45 109 6,698 375424 .514 .696 .304

332 38.37 831 31,881 13461504 .810 .791 .209 56.03 569 31,881 9224376 .703 .759 .241

333 21.33 1,005 21,436 11099993 1.674 .953 .047 30.32 707 21,436 7708389 .795 .787 .213

334 49.65 311 15,442 2604898 2.591 .995 .005 82.58 187 15,442 1582523 2.275 .989 .011

335 52.65 422 22,219 4562835 -.952 .171 .171 83.22 267 22,219 2904196 -.592 .277 .277

336 37.64 55 2,070 57360 .098 .539 .461 47.05 44 2,070 44698 -.212 .416 .416

337 32.38 340 11,010 1822342 -.842 .200 .200 50.27 219 11,010 1146162 -1.264 .103 .103

338 33.01 175 5,777 515254 .443 .671 .329 45.85 126 5,777 368905 .265 .604 .396

339 15.83 307 4,859 751701 .238 .594 .406 23.03 211 4,859 535306 1.113 .867 .133

340 22.77 274 6,240 872649 .596 .724 .276 34.29 182 6,240 566867 -.040 .484 .484

341 69.55 140 9,737 725105 1.308 .905 .095 101.43 96 9,737 513008 1.657 .951 .049

342 57.75 71 4,100 167022 2.153 .984 .016 74.55 55 4,100 126636 1.582 .943 .057

343 26.14 486 12,702 3083273 -.041 .484 .484 36.50 348 12,702 2177717 -.474 .318 .318

344 26.48 1,300 34,428 23568194 3.321 1.000 0 38.77 888 34,428 15945979 2.228 .987 .013

345 19.40 25 485 5354 -1.012 .156 .156 24.25 20 485 4213 -1.017 .155 .155

346 51.01 422 21,528 4370954 -1.343 .090 .090 85.09 253 21,528 2642717 -.815 .208 .208

347 38.45 31 1,192 16500 -1.031 .151 .151 66.22 18 1,192 10097 -.432 .333 .333

348 36.97 302 11,166 1707649 .385 .650 .350 53.43 209 11,166 1187060 .434 .668 .332

349 35.77 312 11,161 1682274 -1.034 .151 .151 51.43 217 11,161 1201546 -.199 .421 .421

350 32.39 870 28,183 12359662 .417 .662 .338 49.27 572 28,183 8118999 .302 .619 .382

351 39.04 99 3,865 203176 1.068 .857 .143 60.39 64 3,865 128755 .569 .715 .285

352 50.57 21 1,062 9930 -.869 .192 .192 66.38 16 1,062 8727 .188 .575 .425

353 19.74 165 3,257 283502 1.225 .890 .110 27.14 120 3,257 200846 .527 .701 .299

354 23.00 299 6,876 1055627 .806 .790 .210 34.73 198 6,876 670964 -.349 .363 .363

355 25.39 440 11,170 2404983 -.775 .219 .219 36.50 306 11,170 1697357 -.207 .418 .418

356 44.74 800 35,793 14206021 -.380 .352 .352 62.91 569 35,793 10153443 -.120 .452 .452

357 30.79 1,026 31,587 16437469 .799 .788 .212 46.66 677 31,587 10846059 .649 .742 .258

358 35.04 539 18,884 5168984 .630 .736 .264 52.17 362 18,884 3433515 .150 .559 .441

359 33.64 66 2,220 78647 1.035 .850 .150 48.26 46 2,220 54404 .769 .779 .221

360 45.25 16 724 5201 -.707 .240 .240 48.27 15 724 5110 -.395 .346 .346

Table 5. Summary of interoccurrence intervals for daily precipitation thresholds of 0.75 and 1.0 inch—Continued

Seq.

no.

Daily precipitation threshold of 0.75 inch and greater Daily precipitation threshold of 1.0 inch and greater

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue
Table 5 123

361 30.00 5 150 481 1.095 .863 .137 75.00 2 150 194 0.719 .764 .236

362 21.93 968 21,229 10081708 -1.013 .156 .156 29.40 722 21,229 7432594 -1.403 .080 .080

363 20.26 108 2,188 109702 -1.287 .099 .099 26.36 83 2,188 84377 -1.117 .132 .132

364 20.23 474 9,588 2272101 -.004 .498 .498 27.71 346 9,588 1644860 -.269 .394 .394

365 18.52 1,203 22,280 13451516 .225 .589 .411 26.31 847 22,280 9312503 -.658 .255 .255

366 17.18 147 2,525 186727 .129 .551 .449 17.66 143 2,525 181138 .069 .528 .473

367 20.01 577 11,543 3407248 .963 .832 .168 29.30 394 11,543 2312843 .588 .722 .278

368 47.34 178 8,426 750977 .033 .513 .487 62.42 135 8,426 567446 -.046 .482 .482

369 -- -- -- -- -- -- -- -- -- -- -- -- -- --

370 110.80 59 6,537 158574 -2.364 .009 .009 217.90 30 6,537 63246 -3.368 0 0

371 180.91 109 19,719 1187166 1.893 .971 .029 352.13 56 19,719 595308 1.014 .845 .155

372 41.83 195 8,156 827027 .968 .833 .167 74.83 109 8,156 488433 1.787 .963 .037

373 26.57 7 186 554 -.683 .247 .247 37.20 5 186 491 .217 .586 .414

374 48.56 18 874 8378 .478 .684 .316 62.43 14 874 6259 .149 .559 .441

375 46.82 229 10,721 1323633 2.052 .980 .020 73.94 145 10,721 824906 1.278 .899 .101

376 37.31 78 2,910 126961 1.816 .965 .035 61.92 47 2,910 75852 1.297 .903 .097

377 28.45 638 18,150 5943010 1.157 .876 .124 43.84 414 18,150 3970471 2.002 .977 .023

378 22.58 644 14,540 4647809 -.320 .375 .375 33.74 431 14,540 3078945 -.625 .266 .266

379 25.86 7 181 744 .799 .788 .212 36.20 5 181 507 .467 .680 .320

380 29.75 48 1,428 36680 .843 .800 .200 42.00 34 1,428 24629 .147 .558 .442

381 18.79 1,011 18,998 9868378 1.519 .936 .064 26.03 730 18,998 7017370 .561 .712 .288

382 19.73 15 296 2423 .613 .730 .270 26.91 11 296 1677 .173 .569 .431

383 39.67 818 32,450 13708556 1.629 .948 .052 53.90 602 32,450 10274098 2.204 .986 .014

384 43.45 188 8,168 814570 1.447 .926 .074 66.95 122 8,168 532212 1.304 .904 .096

385 20.70 832 17,222 7064067 -.699 .242 .242 28.66 601 17,222 5077978 -.798 .213 .213

386 40.67 6 244 599 -.771 .220 .220 48.80 5 244 489 -.768 .221 .221

387 27.03 77 2,081 83155 .576 .718 .282 35.88 58 2,081 62599 .492 .689 .311

388 24.16 102 2,464 125194 -.065 .474 .474 36.78 67 2,464 88349 .997 .841 .159

389 25.93 14 363 2855 .801 .788 .212 33.00 11 363 2015 .053 .521 .479

390 14.92 1,171 17,476 10323661 .530 .702 .298 19.88 879 17,476 7680616 -.001 .500 .500

391 25.89 617 15,972 5079375 1.327 .908 .092 38.39 416 15,972 3377441 .588 .722 .278

392 35.66 29 1,034 10085 -3.053 .001 .001 51.70 20 1,034 7195 -2.356 .009 .009

393 185.86 57 10,594 337272 1.531 .937 .063 378.36 28 10,594 180195 1.970 .976 .024

394 -- -- -- -- -- -- -- -- -- -- -- -- -- --

395 27.88 327 9,115 1568762 1.649 .950 .050 39.29 232 9,115 1152754 2.381 .991 .009

396 20.12 979 19,696 10250394 3.424 1.000 0 28.26 697 19,696 7316116 3.012 .999 .001

397 47.00 303 14,241 2092411 -.910 .182 .182 69.81 204 14,241 1449890 -.046 .482 .482

398 37.54 901 33,819 15575633 1.161 .877 .123 54.02 626 33,819 10781164 .802 .789 .211

399 29.82 658 19,618 6505898 .355 .639 .361 43.99 446 19,618 4512190 1.149 .875 .125

400 18.93 1,018 19,271 9875325 .374 .646 .354 26.15 737 19,271 7160406 .391 .652 .348

401 42.49 136 5,779 358814 -1.756 .040 .040 69.63 83 5,779 219476 -1.339 .090 .090

402 40.50 6 243 844 .669 .748 .252 60.75 4 243 537 .364 .642 .358

403 21.35 634 13,535 4111332 -1.822 .034 .034 29.68 456 13,535 2932449 -1.840 .033 .033

404 20.63 999 20,610 10697144 2.140 .984 .016 30.04 686 20,610 7318513 1.600 .945 .055

405 36.34 327 11,884 2030896 1.416 .922 .078 57.14 208 11,884 1335701 2.016 .978 .022

406 24.01 903 21,685 10124534 1.774 .962 .038 33.21 653 21,685 7269454 1.183 .882 .118

407 23.03 161 3,708 302294 .280 .610 .390 32.24 115 3,708 211529 -.146 .442 .442

408 23.68 1,442 34,142 25230532 1.641 .950 .050 34.18 999 34,142 17433729 1.219 .889 .111

409 76.00 16 1,216 12556 2.014 .978 .022 152.00 8 1,216 6940 2.091 .982 .018

410 18.90 762 14,398 5567750 .716 .763 .237 26.71 539 14,398 3981862 1.053 .854 .146

411 40.64 471 19,141 4568878 .510 .695 .305 64.02 299 19,141 2893662 .336 .632 .369

412 22.90 607 13,897 4416349 2.009 .978 .022 31.58 440 13,897 3207298 1.782 .963 .037

Table 5. Summary of interoccurrence intervals for daily precipitation thresholds of 0.75 and 1.0 inch—Continued

Seq.

no.

Daily precipitation threshold of 0.75 inch and greater Daily precipitation threshold of 1.0 inch and greater

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue
124 Atlas of Interoccurrence Intervals for Selected Thresholds of Daily Precipitation in Texas 

413 29.80 1,012 30,162 15215669 -0.167 .434 .434 42.54 709 30,162 10520782 -0.740 .230 .230

414 24.28 141 3,423 255607 1.218 .888 .112 34.23 100 3,423 179666 .862 .806 .194

415 44.13 487 21,490 5175616 -.418 .338 .338 70.46 305 21,490 3187189 -.831 .203 .203

416 47.43 408 19,352 4280643 2.950 .998 .002 72.75 266 19,352 2801939 2.504 .994 .006

417 27.19 113 3,072 165009 -.908 .182 .182 37.93 81 3,072 124408 -.001 .500 .500

418 40.59 614 24,925 8082003 2.412 .992 .008 65.25 382 24,925 5181217 2.990 .999 .001

419 25.18 900 22,658 10171371 -.126 .450 .450 36.25 625 22,658 6942843 -.843 .200 .200

420 46.01 416 19,138 4010058 .261 .603 .397 70.10 273 19,138 2667521 .605 .727 .273

421 68.85 453 31,191 7098964 .179 .571 .429 134.44 232 31,191 3427386 -1.391 .082 .082

422 124.61 93 11,589 474353 -2.000 .023 .023 214.61 54 11,589 248152 -2.634 .004 .004

423 45.65 254 11,596 1524613 .973 .835 .165 63.37 183 11,596 1082497 .474 .682 .318

424 -- -- -- -- -- -- -- -- -- -- -- -- -- --

425 84.37 252 21,262 2849968 1.755 .960 .040 135.43 157 21,262 1718773 .646 .741 .259

426 66.17 270 17,867 2333817 -.923 .178 .178 110.29 162 17,867 1363941 -1.269 .102 .102

427 -- -- -- -- -- -- -- -- -- -- -- -- -- --

428 26.96 178 4,798 451889 1.346 .911 .089 44.84 107 4,798 284470 1.939 .974 .026

429 25.65 211 5,412 586010 .663 .746 .254 40.09 135 5,412 371669 .350 .637 .363

430 26.30 339 8,915 1575939 1.369 .914 .086 39.27 227 8,915 1052874 1.058 .855 .145

431 21.30 181 3,856 375621 1.780 .962 .038 32.13 120 3,856 237836 .531 .702 .298

432 18.06 481 8,688 2143397 .981 .837 .163 24.54 354 8,688 1532867 -.104 .459 .459

433 35.11 779 27,354 10632363 -.100 .460 .460 50.10 546 27,354 7406179 -.333 .370 .370

434 21.08 645 13,597 4555275 1.708 .956 .044 30.90 440 13,597 3086577 1.157 .876 .124

435 22.96 45 1,033 25265 1.011 .844 .156 36.89 28 1,033 15509 .664 .746 .254

436 30.27 960 29,054 14296038 1.347 .911 .089 43.43 669 29,054 10014277 1.363 .914 .086

437 17.39 1,456 25,322 18763175 1.179 .881 .119 23.71 1,068 25,322 13895493 1.564 .941 .059

438 34.96 534 18,671 5251899 2.142 .984 .016 48.37 386 18,671 3804214 1.895 .971 .029

439 36.12 226 8,164 922755 .006 .503 .497 53.71 152 8,164 607359 -.451 .326 .326

440 36.91 252 9,302 1206184 .801 .788 .212 51.68 180 9,302 877905 1.130 .871 .129

441 56.24 422 23,733 5312329 2.165 .985 .015 96.48 246 23,733 3243076 3.014 .999 .001

442 21.14 604 12,769 4086621 2.543 .995 .005 30.92 413 12,769 2711899 1.003 .842 .158

443 23.07 563 12,987 3642910 -.145 .442 .442 32.80 396 12,987 2532992 -.515 .303 .303

444 41.36 39 1,613 35311 1.327 .908 .092 62.04 26 1,613 24245 1.380 .916 .084

445 48.83 392 19,140 3995111 2.228 .987 .013 69.35 276 19,140 2806325 1.798 .964 .036

446 39.23 30 1,177 19093 .773 .780 .220 51.17 23 1,177 14782 .765 .778 .222

447 45.78 501 22,938 5922464 1.191 .883 .117 70.15 327 22,938 3843378 .777 .781 .219

448 23.87 1,321 31,527 20599431 -.678 .249 .249 34.65 910 31,527 14111111 -.851 .197 .197

449 19.41 274 5,317 723233 -.205 .419 .419 27.84 191 5,317 494309 -.635 .263 .263

450 21.23 967 20,533 10382970 2.470 .993 .007 29.67 692 20,533 7493748 2.497 .994 .006

451 22.52 247 5,562 700315 .531 .702 .298 31.60 176 5,562 499777 .485 .686 .314

452 38.00 8 304 1248 .129 .551 .449 60.80 5 304 940 .917 .820 .180

453 70.10 30 2,103 28370 -.955 .170 .170 161.77 13 2,103 9789 -1.773 .038 .038

454 51.94 612 31,784 9480184 -1.083 .140 .140 79.86 398 31,784 6140862 -1.006 .157 .157

455 55.44 16 887 6694 -.393 .347 .347 88.70 10 887 4904 .579 .719 .281

456 67.00 1 67 61 1.422 .922 .078 67.00 1 67 61 1.422 .922 .078

457 26.23 13 341 2696 1.351 .912 .088 48.71 7 341 1833 2.455 .993 .007

458 15.44 403 6,223 1255000 .030 .512 .488 20.81 299 6,223 927939 -.077 .469 .469

459 30.30 37 1,121 20733 -.003 .499 .499 37.37 30 1,121 16657 -.089 .464 .464

460 25.35 1,291 32,732 21157258 .085 .534 .466 35.58 920 32,732 15008070 -.170 .433 .433

461 34.40 895 30,785 13778351 .008 .503 .497 47.58 647 30,785 9923648 -.156 .438 .438

462 25.38 699 17,740 6339841 1.032 .849 .151 36.58 485 17,740 4416703 1.018 .845 .155

463 22.87 327 7,477 1254399 .818 .793 .207 32.94 227 7,477 867843 .591 .723 .277

464 21.64 1,040 22,500 11866676 .796 .787 .213 29.15 772 22,500 8908288 1.237 .892 .108

Table 5. Summary of interoccurrence intervals for daily precipitation thresholds of 0.75 and 1.0 inch—Continued

Seq.

no.

Daily precipitation threshold of 0.75 inch and greater Daily precipitation threshold of 1.0 inch and greater

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue
Table 5 125

465 21.84 90 1,966 86646 -0.339 .367 .367 29.79 66 1,966 61646 -0.701 .242 .242

466 17.61 1,490 26,233 20069205 1.798 .964 .036 25.13 1,044 26,233 13938363 1.000 .841 .159

467 85.76 129 11,063 778473 1.790 .963 .037 140.04 79 11,063 461478 .863 .806 .194

468 19.86 50 993 17694 -3.518 0 0 23.09 43 993 14390 -3.702 0 0

469 17.05 576 9,821 2747067 -1.196 .116 .116 23.67 415 9,821 1988485 -.855 .196 .196

470 45.50 2 91 91 0 .500 .500 91.00 1 91 45 -.019 .492 .492

471 25.40 527 13,388 3513667 -.159 .437 .437 37.09 361 13,388 2408000 -.116 .454 .454

472 16.21 208 3,372 368882 1.296 .902 .098 26.34 128 3,372 216726 .083 .533 .467

473 26.34 730 19,226 7442434 2.834 .998 .002 36.55 526 19,226 5395254 2.662 .996 .004

474 29.87 843 25,176 10682541 .336 .632 .369 45.61 552 25,176 6938988 -.056 .478 .478

475 25.73 1,242 31,959 20845372 3.072 .999 .001 36.15 884 31,959 14855240 2.659 .996 .004

476 23.81 766 18,237 7152107 1.149 .875 .125 32.45 562 18,237 5472772 2.790 .997 .003

477 29.17 144 4,201 336467 2.336 .990 .010 42.01 100 4,201 240258 2.491 .994 .006

478 25.40 908 23,063 10841512 1.849 .968 .032 35.76 645 23,063 7799784 2.141 .984 .016

479 19.06 94 1,792 77593 -1.322 .093 .093 28.00 64 1,792 48958 -2.026 .021 .021

480 28.85 197 5,684 590817 1.344 .910 .090 38.93 146 5,684 443063 1.419 .922 .078

481 17.10 740 12,650 4796714 1.170 .879 .121 23.25 544 12,650 3581184 1.648 .950 .050

482 24.73 150 3,709 270859 -.558 .289 .289 36.01 103 3,709 196873 .539 .705 .295

483 20.61 154 3,174 257877 1.185 .882 .118 28.60 111 3,174 188589 1.288 .901 .099

484 28.50 96 2,736 138645 .946 .828 .172 40.24 68 2,736 100102 1.087 .861 .139

485 32.62 26 848 8887 -1.712 .043 .043 53.00 16 848 5254 -1.563 .059 .059

486 28.23 1,232 34,779 21644107 .625 .734 .266 40.25 864 34,779 15177097 .517 .697 .303

487 25.02 419 10,484 2124781 -1.156 .124 .124 35.54 295 10,484 1471654 -1.438 .075 .075

488 78.38 359 28,138 5086509 .232 .592 .408 119.23 236 28,138 3402856 .662 .746 .254

489 23.21 501 11,627 2980156 .900 .816 .184 36.11 322 11,627 1913427 .689 .754 .246

490 23.86 327 7,802 1301774 .642 .740 .261 35.46 220 7,802 882815 .736 .769 .231

491 19.41 658 12,770 4288945 .927 .823 .177 28.57 447 12,770 2910420 .723 .765 .235

492 25.16 997 25,088 12915779 1.790 .963 .037 36.57 686 25,088 8778307 .913 .819 .181

493 19.34 1,844 35,661 34208113 3.006 .999 .001 27.64 1,290 35,661 23578912 1.562 .941 .059

494 20.01 213 4,263 455447 .080 .532 .468 28.23 151 4,263 329438 .501 .692 .308

495 15.99 1,272 20,344 14018491 5.155 0 0 22.36 910 20,344 9961439 3.979 1.000 0

496 46.46 464 21,557 4959904 -.308 .379 .379 74.85 288 21,557 2971678 -1.255 .105 .105

497 407.50 2 815 1230 1.247 .894 .106 407.50 2 815 1230 1.247 .894 .106

498 21.55 885 19,069 8826043 2.369 .991 .009 30.91 617 19,069 6145176 1.919 .973 .027

499 35.93 494 17,748 4660213 2.428 .992 .008 53.95 329 17,748 3031486 1.205 .886 .114

500 29.64 39 1,156 22813 .130 .552 .448 42.82 27 1,156 16336 .421 .663 .337

501 29.90 171 5,112 415260 -1.131 .129 .129 39.02 131 5,112 313947 -1.237 .108 .108

502 18.61 1,643 30,570 26010100 2.507 .994 .006 25.78 1,186 30,570 19019612 2.934 .998 .002

503 44.67 137 6,120 401830 -.841 .200 .200 65.11 94 6,120 272165 -.904 .183 .183

504 54.97 67 3,683 126901 .405 .657 .343 87.69 42 3,683 73644 -.537 .296 .296

505 34.55 31 1,071 14158 -1.419 .078 .078 56.37 19 1,071 7762 -1.790 .037 .037

506 22.95 1,630 37,401 31885358 3.220 .999 .001 32.41 1,154 37,401 22670035 2.971 .999 .001

507 15.17 92 1,396 71137 1.791 .963 .037 19.94 70 1,396 54840 1.774 .962 .038

508 30.43 522 15,882 4212481 .642 .740 .260 44.49 357 15,882 2872389 .432 .667 .333

509 36.67 696 25,519 9045930 .851 .802 .198 58.94 433 25,519 5552637 .181 .572 .428

510 45.61 46 2,098 44706 -.864 .194 .194 72.35 29 2,098 30178 -.075 .470 .470

511 16.60 1,120 18,591 10910877 2.783 .997 .003 22.62 822 18,591 8239990 3.894 1.000 0

512 33.33 946 31,532 14754241 -.573 .283 .283 47.06 670 31,532 10431522 -.559 .288 .288

513 30.79 692 21,306 7624456 1.561 .941 .059 45.62 467 21,306 5070719 .721 .764 .236

514 -- -- -- -- -- -- -- -- -- -- -- -- -- --

515 49.04 328 16,084 2532199 -1.256 .105 .105 80.02 201 16,084 1497259 -1.811 .035 .035

516 58.53 47 2,751 65603 .175 .570 .430 137.55 20 2,751 27297 -.060 .476 .476

Table 5. Summary of interoccurrence intervals for daily precipitation thresholds of 0.75 and 1.0 inch—Continued

Seq.

no.

Daily precipitation threshold of 0.75 inch and greater Daily precipitation threshold of 1.0 inch and greater

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue
126 Atlas of Interoccurrence Intervals for Selected Thresholds of Daily Precipitation in Texas 

517 54.79 357 19,560 3569276 0.729 .767 .233 86.93 225 19,560 2194988 -0.065 .474 .474

518 35.69 1,028 36,688 19219936 1.067 .857 .143 56.71 647 36,688 12042377 .645 .741 .259

519 39.57 195 7,716 775487 .745 .772 .228 59.81 129 7,716 514880 .680 .752 .248

520 31.91 21 670 7340 .344 .635 .365 51.54 13 670 4261 -.135 .446 .446

521 17.91 995 17,822 8950443 .518 .698 .302 24.31 733 17,822 6562488 .221 .587 .413

522 30.59 242 7,402 962270 2.004 .977 .023 46.85 158 7,402 622578 1.408 .920 .080

523 32.24 118 3,804 239285 1.245 .893 .107 55.94 68 3,804 142103 1.410 .921 .079

524 115.95 21 2,435 23634 -.600 .274 .274 173.93 14 2,435 16698 -.132 .447 .447

525 -- -- -- -- -- -- -- -- -- -- -- -- -- --

526 42.45 767 32,561 12567138 .307 .621 .379 61.21 532 32,561 8472080 -.872 .192 .192

527 14.94 582 8,692 2605343 1.255 .895 .105 19.71 441 8,692 2031108 2.173 .985 .015

528 14.42 219 3,157 340350 -.396 .346 .346 19.49 162 3,157 245712 -.863 .194 .194

529 19.90 582 11,583 3584271 2.648 .996 .004 28.05 413 11,583 2645731 3.736 1.000 0

530 17.03 2,004 34,124 35137149 2.143 .984 .016 23.63 1,444 34,124 25483177 2.259 .988 .012

531 25.66 248 6,363 812833 .824 .795 .205 36.99 172 6,363 604996 2.398 .992 .008

532 27.95 1,290 36,056 23890172 1.696 .955 .045 41.02 879 36,056 16320809 1.537 .938 .062

533 54.80 470 25,757 5957377 -.593 .277 .277 89.75 287 25,757 3582585 -.901 .184 .184

534 58.00 17 986 8993 .522 .699 .301 70.43 14 986 6946 .041 .517 .484

535 25.15 1,668 41,954 35068929 .160 .564 .436 36.29 1,156 41,954 24525840 .671 .749 .251

536 25.17 6 151 225 -2.135 .016 .016 25.17 6 151 225 -2.135 .016 .016

537 26.71 1,193 31,864 19271876 .834 .798 .202 38.39 830 31,864 13527023 1.145 .874 .126

538 45.80 50 2,290 55353 -.406 .342 .342 61.89 37 2,290 42513 .037 .515 .485

539 38.16 517 19,726 5159478 .466 .679 .321 58.02 340 19,726 3306146 -.450 .326 .326

540 23.47 71 1,666 70400 2.778 .997 .003 28.24 59 1,666 58573 2.552 .995 .005

541 23.03 1,521 35,035 26832431 .477 .683 .317 32.47 1,079 35,035 18598299 -.912 .181 .181

542 47.36 25 1,184 13092 -.999 .159 .159 62.32 19 1,184 10924 -.218 .414 .414

543 44.78 187 8,373 789247 .193 .576 .424 72.81 115 8,373 457036 -.942 .173 .173

544 31.14 942 29,330 13589725 -.865 .194 .194 44.04 666 29,330 9739509 -.125 .450 .450

545 32.80 256 8,397 1040814 -.877 .190 .190 49.11 171 8,397 700626 -.546 .292 .292

546 17.59 1,785 31,403 28919494 2.330 .990 .010 25.76 1,219 31,403 19849634 2.242 .988 .012

547 34.01 519 17,650 4601625 .185 .573 .427 50.57 349 17,650 3096855 .178 .571 .429

548 16.96 773 13,112 5168017 .952 .829 .171 23.41 560 13,112 3804373 1.485 .931 .069

549 219.75 4 879 1933 .345 .635 .365 879.00 1 879 770 1.303 .904 .096

550 25.39 33 838 15148 .951 .829 .171 32.23 26 838 11717 .667 .748 .252

551 21.60 254 5,486 742754 1.824 .966 .034 30.48 180 5,486 526866 1.559 .941 .060

552 19.15 1,022 19,567 10725254 4.023 1.000 0 27.37 715 19,567 7447130 2.992 .999 .001

553 25.33 6 152 636 1.675 .953 .047 152.00 1 152 104 .638 .738 .262

554 17.87 666 11,901 4007684 .504 .693 .307 24.85 479 11,901 2919549 .921 .821 .179

555 24.50 6 147 411 -.289 .386 .386 147.00 1 147 19 -1.284 .100 .100

556 16.59 1,205 19,994 12581419 2.670 .996 .004 22.17 902 19,994 9551562 3.082 .999 .001

557 21.08 13 274 1851 .246 .597 .403 34.25 8 274 924 -.769 .221 .221

558 19.90 107 2,129 118336 .698 .757 .243 27.65 77 2,129 86956 .925 .823 .178

559 18.84 31 584 9195 .152 .561 .439 27.81 21 584 6131 -.001 .499 .499

560 22.18 11 244 1477 .578 .718 .282 30.50 8 244 977 .005 .502 .498

561 16.68 1,067 17,792 9992478 2.983 .999 .001 22.35 796 17,792 7502447 2.907 .998 .002

562 16.61 1,246 20,691 13569971 3.223 .999 .001 22.59 916 20,691 10024513 3.032 .999 .001

563 16.93 998 16,893 9153430 4.698 1.000 0 22.49 751 16,893 6769725 3.191 .999 .001

564 17.80 1,066 18,979 10817960 3.925 1.000 0 24.52 774 18,979 7838514 3.239 .999 .001

565 15.35 319 4,897 818599 1.486 .931 .069 21.67 226 4,897 557999 .218 .586 .414

566 16.95 884 14,981 6775450 1.197 .884 .116 23.05 650 14,981 5010518 1.285 .901 .099

567 32.21 273 8,792 1484463 6.781 0 0 47.78 184 8,792 1026251 6.314 0 0

568 17.08 926 15,815 7592335 1.943 .974 .026 22.56 701 15,815 5782022 1.976 .976 .024

Table 5. Summary of interoccurrence intervals for daily precipitation thresholds of 0.75 and 1.0 inch—Continued

Seq.

no.

Daily precipitation threshold of 0.75 inch and greater Daily precipitation threshold of 1.0 inch and greater

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue
Table 5 127

569 20.17 457 9,218 2142156 0.630 .736 .264 29.83 309 9,218 1424851 0.014 .506 .494

570 13.37 272 3,637 490407 -.244 .404 .404 17.40 209 3,637 381198 .075 .530 .470

571 17.85 1,016 18,133 9815677 3.621 1.000 0 24.60 737 18,133 7270029 4.138 1.000 0

572 24.99 511 12,769 3185061 -.929 .176 .176 32.83 389 12,769 2358756 -1.717 .043 .043

573 45.01 112 5,041 267983 -.929 .176 .176 65.47 77 5,041 183327 -.842 .200 .200

574 16.74 667 11,163 3823084 1.204 .886 .114 23.26 480 11,163 2773818 1.341 .910 .090

575 33.66 520 17,501 4443228 -.929 .176 .176 47.82 366 17,501 3127404 -.779 .218 .218

576 29.89 121 3,617 229665 .944 .827 .173 45.79 79 3,617 151985 .982 .837 .163

577 29.66 626 18,568 6126778 2.349 .991 .009 42.78 434 18,568 4349990 2.872 .998 .002

578 17.99 1,120 20,145 11929125 3.329 1.000 0 25.06 804 20,145 8373750 1.671 .953 .047

579 24.04 586 14,090 4304999 1.794 .964 .036 36.79 383 14,090 2762081 .802 .789 .211

580 18.25 4 73 141 -.119 .453 .453 36.50 2 73 80 .235 .593 .407

581 15.48 153 2,368 172987 -.966 .167 .167 21.33 111 2,368 127192 -.588 .278 .278

582 26.88 688 18,495 6519181 1.120 .869 .131 36.99 500 18,495 4738923 .965 .833 .167

583 81.73 198 16,182 1825579 3.401 1.000 0 118.99 136 16,182 1220300 2.201 .986 .014

584 24.40 10 244 1227 .031 .513 .487 27.11 9 244 1092 -.028 .489 .489

585 32.50 404 13,130 2704936 .691 .755 .245 46.40 283 13,130 1880462 .354 .638 .362

586 -- -- -- -- -- -- -- -- -- -- -- -- -- --

587 26.65 137 3,651 252503 .195 .577 .423 36.88 99 3,651 192659 1.138 .872 .128

588 28.69 298 8,550 1224029 -1.172 .121 .121 43.85 195 8,550 797530 -1.047 .148 .148

589 20.67 317 6,553 1104406 1.952 .975 .025 30.06 218 6,553 750547 1.299 .903 .097

590 13.70 27 370 5952 1.724 .958 .042 18.50 20 370 4149 .940 .826 .174

591 19.03 192 3,653 352753 .141 .556 .444 30.70 119 3,653 225750 .730 .767 .233

592 27.36 807 22,076 9132402 1.241 .893 .107 40.88 540 22,076 6056490 .648 .741 .259

593 17.35 894 15,514 7367654 3.233 .999 .001 23.90 649 15,514 5399566 3.202 .999 .001

594 18.13 324 5,874 969455 .585 .721 .279 25.65 229 5,874 685806 .516 .697 .303

595 31.06 297 9,226 1398384 .617 .731 .269 47.80 193 9,226 920554 .817 .793 .207

596 23.39 1,099 25,710 14404574 1.126 .870 .130 32.71 786 25,710 10475678 1.786 .963 .037

597 14.98 1,373 20,570 14303691 .829 .796 .204 20.39 1,009 20,570 10726274 1.849 .968 .032

598 14.75 71 1,047 29702 -2.932 .002 .002 20.14 52 1,047 21663 -2.551 .005 .005

599 37.18 476 17,699 4311266 .887 .812 .188 56.73 312 17,699 2799560 .427 .665 .335

600 23.14 844 19,532 8484359 1.477 .930 .070 31.97 611 19,532 6230478 1.890 .971 .029

601 16.75 1,929 32,319 31555759 .937 .826 .174 24.26 1,332 32,319 21308352 -.635 .263 .263

602 20.53 749 15,379 5701552 -.476 .317 .317 29.46 522 15,379 3929910 -.828 .204 .204

603 18.42 338 6,226 1147701 2.890 .998 .002 27.92 223 6,226 721872 1.031 .849 .151

604 24.85 494 12,277 3056242 .302 .619 .381 37.20 330 12,277 2026225 .008 .503 .497

605 39.81 156 6,210 508009 1.055 .854 .146 63.37 98 6,210 325325 1.185 .882 .118

606 48.31 109 5,266 301008 .883 .811 .189 75.23 70 5,266 200037 1.237 .892 .108

607 44.77 87 3,895 172717 .313 .623 .377 68.33 57 3,895 124412 1.579 .943 .057

608 33.07 640 21,162 6841590 .451 .674 .326 46.51 455 21,162 4865805 .395 .654 .347

609 107.22 27 2,895 33422 -1.304 .096 .096 152.37 19 2,895 24319 -.874 .191 .191

610 33.25 917 30,487 13224424 -2.829 .002 .002 48.16 633 30,487 9229872 -1.894 .029 .029

611 42.81 192 8,219 853031 1.947 .974 .026 69.65 118 8,219 532468 1.845 .967 .033

612 41.49 87 3,610 175926 1.944 .974 .026 63.33 57 3,610 123593 2.632 .996 .004

613 36.26 19 689 5952 -.685 .247 .247 43.06 16 689 4972 -.679 .249 .249

614 41.41 81 3,354 117531 -2.101 .018 .018 60.98 55 3,354 81612 -1.479 .070 .070

615 30.50 2 61 64 .121 .548 .452 30.50 2 61 64 .121 .548 .452

616 32.38 58 1,878 59805 1.294 .902 .098 49.42 38 1,878 38493 .841 .800 .200

617 14.37 122 1,753 91222 -2.811 .002 .002 20.87 84 1,753 62737 -2.348 .009 .009

618 15.67 1,317 20,642 14359098 3.544 1.000 0 21.77 948 20,642 10664525 4.798 1.000 0

619 28.59 995 28,443 13982348 -.649 .258 .258 40.17 708 28,443 10031828 -.169 .433 .433

620 30.30 23 697 9013 1.034 .849 .151 46.47 15 697 6045 1.049 .853 .147

Table 5. Summary of interoccurrence intervals for daily precipitation thresholds of 0.75 and 1.0 inch—Continued

Seq.

no.

Daily precipitation threshold of 0.75 inch and greater Daily precipitation threshold of 1.0 inch and greater

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue
128 Atlas of Interoccurrence Intervals for Selected Thresholds of Daily Precipitation in Texas 

621 21.32 774 16,498 6773828 2.937 .998 .002 29.57 558 16,498 4944376 3.035 .999 .001

622 19.62 1,844 36,185 32954814 -.909 .182 .182 27.99 1,293 36,185 23281472 -.299 .383 .383

623 27.17 271 7,364 1023441 .732 .768 .232 41.14 179 7,364 673634 .512 .696 .304

624 20.68 94 1,944 80246 -2.044 .020 .020 28.17 69 1,944 59933 -1.531 .063 .063

625 28.54 349 9,960 1873560 2.523 .994 .006 40.32 247 9,960 1312340 1.821 .966 .034

626 23.64 458 10,827 2426129 -.796 .213 .213 32.51 333 10,827 1795035 -.134 .447 .447

627 95.33 124 11,821 766655 .888 .813 .187 164.18 72 11,821 446024 .707 .760 .240

628 65.83 76 5,003 145696 -3.528 0 0 113.71 44 5,003 77813 -3.367 0 0

629 31.16 849 26,452 11137099 -.413 .340 .340 45.77 578 26,452 7686639 .229 .591 .409

630 28.43 349 9,923 1728145 -.064 .474 .474 40.17 247 9,923 1202337 -.514 .304 .304

631 26.19 416 10,894 2266033 .001 .501 .499 39.62 275 10,894 1487681 -.196 .422 .422

632 25.03 318 7,960 1305688 .977 .836 .164 35.86 222 7,960 906301 .664 .747 .253

633 20.51 83 1,702 74070 .768 .779 .221 32.73 52 1,702 47820 1.007 .843 .157

634 48.33 6 290 488 -1.863 .031 .031 96.67 3 290 406 -.200 .421 .421

635 32.30 831 26,842 11118641 -.153 .439 .439 45.04 596 26,842 8003446 .024 .510 .490

636 15.03 1,380 20,742 14586641 1.235 .892 .109 20.68 1,003 20,742 10751134 1.841 .967 .033

637 46.23 528 24,410 6847254 2.489 .994 .006 66.51 367 24,410 4785115 2.266 .988 .012

638 39.28 283 11,115 1668555 1.775 .962 .038 62.10 179 11,115 1049915 1.284 .900 .100

639 25.48 205 5,224 555090 .909 .818 .182 41.13 127 5,224 335772 .238 .594 .406

640 15.39 381 5,865 1143833 .803 .789 .211 19.29 304 5,865 921318 1.011 .844 .156

641 46.00 26 1,196 15716 .095 .538 .462 92.00 13 1,196 7758 -.013 .495 .495

642 41.71 7 292 1149 .570 .715 .285 58.40 5 292 714 -.085 .466 .466

643 22.61 1,453 32,853 24460977 1.641 .950 .050 31.05 1,058 32,853 17586977 .673 .750 .250

644 49.46 50 2,473 69466 1.514 .935 .065 65.08 38 2,473 52827 1.327 .908 .092

645 41.20 666 27,442 9485612 1.699 .955 .045 57.65 476 27,442 6803917 1.578 .943 .057

646 149.03 139 20,715 1582133 2.020 .978 .022 304.63 68 20,715 770224 1.337 .909 .091

647 27.49 33 907 16430 .974 .835 .165 41.23 22 907 11853 1.528 .937 .063

648 28.13 68 1,913 64966 -.017 .493 .493 36.09 53 1,913 53706 .749 .773 .227

649 91.80 89 8,170 325534 -1.709 .044 .044 163.40 50 8,170 180011 -1.453 .073 .073

650 32.20 447 14,391 3139899 -.871 .192 .192 44.83 321 14,391 2340812 .417 .662 .338

651 47.49 59 2,802 76917 -.924 .178 .178 82.41 34 2,802 47914 .059 .524 .476

652 31.92 25 798 9985 .009 .503 .497 44.33 18 798 7092 -.092 .463 .463

653 24.07 45 1,083 25953 .756 .775 .225 30.94 35 1,083 20001 .567 .715 .285

654 45.80 226 10,351 1204846 .783 .783 .217 70.90 146 10,351 823309 1.875 .970 .030

655 26.99 106 2,861 138583 -1.535 .062 .062 37.16 77 2,861 98429 -1.617 .053 .053

656 18.38 258 4,743 606720 -.233 .408 .408 23.25 204 4,743 478781 -.256 .399 .399

657 34.82 333 11,595 1999044 1.121 .869 .131 57.69 201 11,595 1197215 .673 .749 .251

658 32.55 176 5,729 515130 .500 .692 .308 49.39 116 5,729 337370 .286 .612 .388

659 26.19 106 2,776 145228 -.230 .409 .409 38.03 73 2,776 96691 -.677 .249 .249

660 18.62 258 4,805 640341 .920 .821 .179 26.69 180 4,805 435757 .178 .571 .429

661 18.04 157 2,832 229110 .664 .746 .254 25.29 112 2,832 155802 -.323 .374 .374

662 29.52 186 5,490 539164 1.323 .907 .093 40.97 134 5,490 391628 1.297 .903 .097

663 52.70 619 32,622 10162803 .283 .611 .389 84.08 388 32,622 6368203 .213 .584 .416

664 29.22 1,269 37,084 23995181 1.220 .889 .111 42.87 865 37,084 16200775 .514 .696 .304

665 62.96 299 18,826 2795485 -.202 .420 .420 97.04 194 18,826 1782951 -.570 .284 .284

666 76.41 17 1,299 11960 .594 .724 .276 162.38 8 1,299 4907 -.273 .393 .393

667 44.88 305 13,689 1995826 -1.329 .092 .092 63.67 215 13,689 1409639 -1.069 .143 .143

668 57.07 136 7,761 516630 -.426 .335 .335 88.19 88 7,761 318866 -1.076 .141 .141

669 17.91 317 5,676 938287 1.325 .907 .093 26.77 212 5,676 617299 .656 .744 .256

670 36.57 232 8,485 983160 -.030 .488 .488 58.52 145 8,485 603141 -.408 .342 .342

671 21.71 866 18,797 8421206 1.767 .961 .039 31.91 589 18,797 5848056 2.372 .991 .009

672 33.29 581 19,344 5673688 .403 .657 .343 51.72 374 19,344 3566602 -.470 .319 .319

Table 5. Summary of interoccurrence intervals for daily precipitation thresholds of 0.75 and 1.0 inch—Continued

Seq.

no.

Daily precipitation threshold of 0.75 inch and greater Daily precipitation threshold of 1.0 inch and greater

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue
Table 5 129

673 36.06 152 5,481 459375 2.195 .986 .014 54.81 100 5,481 295511 1.356 .912 .088

674 22.63 79 1,788 66938 -.804 .211 .211 28.84 62 1,788 49163 -1.542 .062 .062

675 35.80 74 2,649 90609 -1.126 .130 .130 49.98 53 2,649 63926 -1.127 .130 .130

676 24.26 137 3,324 210195 -1.558 .060 .060 36.13 92 3,324 144661 -.896 .185 .185

677 52.82 389 20,545 3989584 -.055 .478 .478 81.53 252 20,545 2582159 -.069 .472 .472

678 39.25 4 157 197 -1.291 .098 .098 39.25 4 157 197 -1.291 .098 .098

679 48.77 464 22,630 5273159 .163 .565 .435 77.50 292 22,630 3185604 -1.060 .145 .145

680 25.06 174 4,360 385480 .371 .645 .355 36.95 118 4,360 257210 -.002 .499 .499

681 19.49 43 838 17878 -.088 .465 .465 22.05 38 838 16379 .307 .620 .380

682 28.29 180 5,092 459299 .052 .521 .479 44.28 115 5,092 295417 .167 .566 .434

683 22.38 545 12,199 3422573 1.196 .884 .116 30.73 397 12,199 2517298 1.365 .914 .086

684 23.41 663 15,522 5270905 1.087 .861 .139 32.96 471 15,522 3678366 .236 .593 .407

685 16.29 2,162 35,218 39712243 3.473 1.000 0 22.16 1,589 35,218 29234428 3.094 .999 .001

686 29.24 200 5,847 629926 1.895 .971 .029 41.18 142 5,847 461715 2.316 .990 .010

687 24.97 62 1,548 46601 -.394 .347 .347 32.94 47 1,548 34526 -.605 .273 .273

688 17.81 252 4,487 554529 -.527 .299 .299 24.39 184 4,487 407392 -.308 .379 .379

689 21.07 280 5,899 863914 1.336 .909 .091 33.14 178 5,899 531658 .293 .615 .385

690 18.21 688 12,527 4314440 .054 .522 .478 25.41 493 12,527 3127724 .496 .690 .310

691 15.64 1,171 18,319 11219708 2.730 .997 .003 21.81 840 18,319 8281519 3.833 1.000 0

692 27.47 684 18,792 6642245 1.518 .935 .065 39.40 477 18,792 4875030 3.318 1.000 0

693 42.30 453 19,163 4606744 2.262 .988 .012 67.48 284 19,163 2857625 1.464 .928 .072

694 22.82 320 7,301 1194743 .705 .760 .240 32.89 222 7,301 839251 .918 .821 .179

695 51.65 262 13,531 1784489 .189 .575 .425 76.45 177 13,531 1190946 -.126 .450 .450

696 50.68 253 12,822 1613736 -.140 .444 .444 83.26 154 12,822 967241 -.437 .331 .331

697 16.53 1,427 23,585 17217320 1.514 .935 .065 22.53 1,047 23,585 12770155 1.922 .973 .027

698 32.72 1,147 37,526 22168642 1.765 .961 .039 48.42 775 37,526 14552960 .039 .515 .485

699 27.29 58 1,583 47494 .456 .676 .324 35.18 45 1,583 36328 .232 .592 .408

700 25.21 780 19,662 8051120 2.416 .992 .008 36.82 534 19,662 5473196 1.704 .956 .044

701 21.60 83 1,793 77863 .732 .768 .232 35.16 51 1,793 43985 -.470 .319 .319

702 40.40 30 1,212 15011 -1.654 .049 .049 60.60 20 1,212 10290 -1.170 .121 .121

703 24.72 191 4,722 471092 1.069 .857 .143 34.22 138 4,722 347780 1.372 .915 .085

704 38.55 11 424 1471 -2.121 .017 .017 42.40 10 424 1116 -2.594 .005 .005

705 19.97 643 12,843 4281266 1.619 .947 .053 28.86 445 12,843 3006824 1.908 .972 .028

706 16.85 2,129 35,879 39091429 1.880 .970 .030 23.75 1,511 35,879 27788699 1.694 .955 .045

707 15.78 590 9,308 2895401 2.291 .989 .011 21.50 433 9,308 2132241 2.094 .982 .018

708 58.35 277 16,163 2333312 1.220 .889 .111 88.32 183 16,163 1562828 1.330 .908 .092

709 -- -- -- -- -- -- -- -- -- -- -- -- -- --

710 49.92 24 1,198 14322 -.032 .487 .487 70.47 17 1,198 9412 -.541 .294 .294

711 40.83 363 14,820 2871235 2.226 .987 .013 61.75 240 14,820 1947108 2.546 .995 .005

712 43.26 31 1,341 18449 -1.084 .139 .139 63.86 21 1,341 12332 -.986 .162 .162

713 19.27 527 10,153 2823556 2.203 .986 .014 27.89 364 10,153 2010166 2.903 .998 .002

714 73.00 5 365 503 -1.738 .041 .041 121.67 3 365 255 -1.603 .055 .055

715 50.35 29 1,460 20307 -.380 .352 .352 76.84 19 1,460 12456 -.770 .221 .221

716 58.48 108 6,316 348440 .389 .651 .349 85.35 74 6,316 261154 1.751 .960 .040

717 52.28 634 33,144 10347522 -.661 .255 .255 88.15 376 33,144 5995699 -1.269 .102 .102

718 15.23 452 6,885 1501622 -1.287 .099 .099 21.52 320 6,885 1071971 -.833 .202 .202

719 14.69 297 4,364 636354 -.539 .295 .295 20.49 213 4,364 460989 -.205 .419 .419

720 18.23 1,823 33,230 30037999 -.613 .270 .270 25.80 1,288 33,230 21209630 -.553 .290 .290

721 25.40 1,435 36,455 26796511 1.606 .946 .054 37.39 975 36,455 18362807 1.799 .964 .036

722 22.42 72 1,614 59850 .442 .671 .329 36.68 44 1,614 38638 1.013 .844 .156

723 13.73 164 2,252 188184 .423 .664 .336 19.58 115 2,252 132972 .500 .691 .309

724 31.23 293 9,151 1353760 .291 .614 .386 45.30 202 9,151 929792 .148 .559 .441

Table 5. Summary of interoccurrence intervals for daily precipitation thresholds of 0.75 and 1.0 inch—Continued

Seq.

no.

Daily precipitation threshold of 0.75 inch and greater Daily precipitation threshold of 1.0 inch and greater

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue
130 Atlas of Interoccurrence Intervals for Selected Thresholds of Daily Precipitation in Texas 

725 33.81 271 9,162 1329181 2.015 .978 .022 49.26 186 9,162 903179 1.417 .922 .078

726 25.89 45 1,165 26965 .334 .631 .369 43.15 27 1,165 15139 -.337 .368 .368

727 18.94 1,335 25,281 17025693 .565 .714 .286 26.70 947 25,281 12046024 .336 .632 .368

728 17.98 573 10,305 3118581 2.334 .990 .010 25.63 402 10,305 2199639 2.152 .984 .016

729 29.60 218 6,453 768528 2.369 .991 .009 40.59 159 6,453 568093 2.345 .990 .010

730 -- -- -- -- -- -- -- -- -- -- -- -- -- --

731 23.86 262 6,252 765970 -1.816 .035 .035 30.20 207 6,252 605581 -1.598 .055 .055

732 32.94 207 6,819 719147 .473 .682 .318 49.06 139 6,819 477156 .139 .555 .445

733 344.00 1 344 307 1.360 .913 .087 344.00 1 344 307 1.360 .913 .087

734 62.49 369 23,057 3964230 -2.267 .012 .012 95.28 242 23,057 2540814 -2.406 .008 .008

735 43.98 45 1,979 38358 -1.610 .054 .054 70.68 28 1,979 23756 -1.307 .096 .096

736 31.14 260 8,096 1077847 .673 .749 .251 51.24 158 8,096 625005 -.496 .310 .310

737 105.88 25 2,647 35769 .702 .759 .241 189.07 14 2,647 24921 2.236 .987 .013

738 70.96 202 14,333 1518043 1.197 .884 .116 111.11 129 14,333 977314 1.124 .870 .131

739 85.98 58 4,987 120116 -2.235 .013 .013 142.49 35 4,987 77745 -1.119 .132 .132

740 74.46 13 968 5440 -.846 .199 .199 193.60 5 968 2441 .034 .513 .487

741 71.00 2 142 77 -1.121 .131 .131 71.00 2 142 77 -1.121 .131 .131

742 23.26 1,138 26,466 15543195 1.878 .970 .030 32.76 808 26,466 11057307 1.681 .954 .046

743 16.39 2,037 33,395 35483367 3.380 1.000 0 23.03 1,450 33,395 25885816 4.561 1.000 0

744 37.92 167 6,333 543941 .641 .739 .261 55.55 114 6,333 363113 .109 .544 .456

745 26.57 337 8,954 1571942 1.332 .909 .092 36.40 246 8,954 1179713 1.933 .973 .027

746 31.28 657 20,552 7160933 2.694 .996 .004 46.08 446 20,552 4845764 2.096 .982 .018

747 43.39 451 19,569 4543578 1.090 .862 .138 68.42 286 19,569 2993730 2.045 .980 .020

748 21.55 1,529 32,946 24592845 -1.598 .055 .055 28.57 1,153 32,946 18176151 -2.531 .006 .006

749 26.98 503 13,573 3035274 -4.305 0 0 38.45 353 13,573 2099166 -4.027 0 0

750 15.81 1,175 18,579 11374963 2.501 .994 .006 22.07 842 18,579 8267330 2.863 .998 .002

751 22.70 336 7,628 1286599 .126 .550 .450 32.19 237 7,628 945307 1.221 .889 .111

752 101.33 12 1,216 7871 .473 .682 .318 173.71 7 1,216 4153 -.111 .456 .456

753 23.37 87 2,033 93967 1.011 .844 .156 33.88 60 2,033 65983 1.098 .864 .136

754 17.52 147 2,575 179064 -1.132 .129 .129 25.00 103 2,575 113226 -2.570 .005 .005

755 44.98 478 21,499 5184507 .341 .633 .367 63.61 338 21,499 3581420 -.455 .325 .325

756 -- -- -- -- -- -- -- -- -- -- -- -- -- --

757 42.04 139 5,844 408363 .111 .544 .456 60.88 96 5,844 269274 -.680 .248 .248

758 21.17 1,528 32,344 25217706 1.389 .918 .082 29.65 1,091 32,344 17994027 1.136 .872 .128

759 35.63 432 15,392 3631537 3.323 1.000 0 51.65 298 15,392 2495283 2.632 .996 .004

760 45.13 473 21,345 5305287 1.919 .973 .027 64.68 330 21,345 3688055 1.484 .931 .069

761 44.51 304 13,531 2010274 -.682 .248 .248 62.07 218 13,531 1422994 -.900 .184 .184

762 73.10 346 25,291 4460405 .626 .734 .266 111.91 226 25,291 2794501 -.578 .282 .282

763 28.19 42 1,184 22678 -.987 .162 .162 37.00 32 1,184 16902 -1.056 .146 .146

764 24.52 1,337 32,783 22062250 .424 .664 .336 36.03 910 32,783 14922871 .023 .509 .491

765 25.84 472 12,195 2939052 .798 .787 .213 34.55 353 12,195 2211197 .889 .813 .187

766 22.66 118 2,674 136003 -2.595 .005 .005 33.43 80 2,674 92714 -2.063 .020 .020

767 38.65 859 33,202 13821140 -1.563 .059 .059 60.04 553 33,202 9031442 -.661 .254 .254

768 36.60 927 33,925 15775787 .173 .569 .431 55.52 611 33,925 10293675 -.291 .386 .386

769 40.73 52 2,118 52778 -.519 .302 .302 57.24 37 2,118 40846 .447 .673 .327

770 108.48 75 8,136 328837 1.167 .878 .122 184.91 44 8,136 198735 1.267 .897 .103

771 43.69 85 3,714 158984 .115 .546 .454 58.03 64 3,714 124958 .712 .762 .238

772 36.60 5 183 564 .902 .816 .184 45.75 4 183 389 .218 .586 .414

773 36.93 14 517 3041 -1.035 .150 .150 51.70 10 517 2312 -.578 .282 .282

774 37.83 816 30,870 12703828 .428 .666 .334 55.22 559 30,870 8879965 1.195 .884 .116

775 25.33 12 304 1864 .132 .552 .448 43.43 7 304 1007 -.246 .403 .403

776 22.56 311 7,015 1182398 2.564 .995 .005 31.46 223 7,015 866321 2.783 .997 .003

Table 5. Summary of interoccurrence intervals for daily precipitation thresholds of 0.75 and 1.0 inch—Continued

Seq.

no.

Daily precipitation threshold of 0.75 inch and greater Daily precipitation threshold of 1.0 inch and greater

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue
Table 5 131

777 22.84 300 6,852 1049973 0.647 .741 .259 31.87 215 6,852 768977 1.117 .868 .132

778 65.87 148 9,749 599823 -3.552 0 0 108.32 90 9,749 380514 -2.180 .015 .015

779 43.98 364 16,007 3100357 2.122 .983 .017 65.07 246 16,007 2156447 2.588 .995 .005

780 21.33 1,620 34,558 29538428 3.851 1.000 0 30.97 1,116 34,558 20187559 2.713 .997 .003

781 40.20 861 34,614 14713144 -.642 .261 .261 62.26 556 34,614 9621266 -.006 .498 .498

782 15.90 585 9,303 2893196 2.649 .996 .004 21.74 428 9,303 2128056 2.470 .993 .007

783 47.10 31 1,460 18753 -1.652 .049 .049 81.11 18 1,460 11052 -1.168 .122 .122

784 51.32 92 4,721 198502 -1.428 .077 .077 80.02 59 4,721 127175 -1.155 .124 .124

785 63.60 300 19,079 3042393 1.893 .971 .029 93.53 204 19,079 2099508 1.951 .974 .026

786 68.33 286 19,541 2773778 -.216 .415 .415 112.31 174 19,541 1681521 -.249 .402 .402

787 21.78 278 6,055 820032 -.742 .229 .229 32.21 188 6,055 538280 -1.289 .099 .099

788 20.15 80 1,612 63038 -.347 .364 .364 27.79 58 1,612 47402 .185 .573 .427

789 20.16 414 8,344 1721144 -.124 .451 .451 27.09 308 8,344 1266590 -.435 .332 .332

790 15.63 142 2,219 152815 -.620 .268 .268 22.19 100 2,219 110640 -.048 .481 .481

791 29.46 160 4,714 394253 .995 .840 .160 38.64 122 4,714 297633 .671 .749 .251

792 26.47 17 450 4797 1.815 .965 .035 37.50 12 450 3387 1.527 .937 .063

793 19.14 1,002 19,181 9612653 .017 .507 .493 25.89 741 19,181 7116229 .064 .526 .474

794 17.57 665 11,685 3889313 .047 .519 .481 25.80 453 11,685 2669205 .314 .623 .377

795 27.99 609 17,047 5332492 1.167 .878 .122 39.92 427 17,047 3877645 2.342 .990 .010

796 60.06 87 5,225 224497 -.198 .421 .421 91.67 57 5,225 152632 .327 .628 .372

797 45.75 622 28,459 9099762 1.215 .888 .112 65.88 432 28,459 6333997 1.094 .863 .137

798 43.38 16 694 4205 -1.681 .046 .046 69.40 10 694 2934 -.846 .199 .199

799 38.47 238 9,155 1118583 .715 .763 .237 62.28 147 9,155 672636 -.008 .497 .497

800 42.52 27 1,148 15384 -.066 .474 .474 76.53 15 1,148 8990 .296 .616 .384

801 77.10 192 14,804 1483606 1.054 .854 .146 120.36 123 14,804 939310 .609 .729 .271

802 108.00 14 1,512 8461 -1.300 .097 .097 137.46 11 1,512 6155 -1.493 .068 .068

803 25.61 285 7,299 1031729 -.236 .407 .407 37.24 196 7,299 699188 -.546 .292 .292

804 48.64 14 681 4138 -.855 .196 .196 61.91 11 681 2345 -2.148 .016 .016

805 35.58 323 11,493 1799785 -.945 .172 .172 53.46 215 11,493 1195002 -.832 .203 .203

806 18.43 931 17,161 8225526 1.568 .942 .058 26.36 651 17,161 5772899 1.479 .930 .070

807 21.96 598 13,131 4219251 3.162 .999 .001 34.20 384 13,131 2705414 2.481 .993 .007

808 25.84 697 18,012 6325309 .351 .637 .363 38.32 470 18,012 4391670 1.409 .921 .079

809 47.78 386 18,442 3483727 -.723 .235 .235 74.36 248 18,442 2252940 -.404 .343 .343

810 57.77 356 20,566 3797208 1.218 .888 .112 86.78 237 20,566 2519168 .898 .815 .185

811 16.25 454 7,376 1741886 1.489 .932 .068 23.57 313 7,376 1178068 .630 .736 .264

812 31.23 214 6,684 749577 1.218 .888 .112 43.69 153 6,684 518166 .287 .613 .387

813 11.86 7 83 273 -.276 .391 .391 11.86 7 83 273 -.276 .391 .391

814 54.60 447 24,404 5532950 .528 .701 .299 102.97 237 24,404 2896358 .041 .517 .484

815 17.05 1,782 30,377 27847456 2.111 .983 .017 23.49 1,293 30,377 20091186 1.435 .924 .076

816 16.59 779 12,922 5184446 1.454 .927 .073 23.93 540 12,922 3696012 2.389 .992 .008

817 25.29 246 6,220 766142 .038 .515 .485 35.34 176 6,220 545525 -.077 .469 .469

818 23.81 833 19,833 8344413 .508 .694 .306 34.86 569 19,833 5757434 .842 .800 .200

819 57.61 501 28,862 7037440 -1.032 .151 .151 98.17 294 28,862 4037995 -1.433 .076 .076

820 42.43 21 891 10081 .616 .731 .269 68.54 13 891 7038 1.344 .911 .089

821 57.69 138 7,961 561888 .466 .679 .321 90.47 88 7,961 344018 -.291 .386 .386

822 30.19 631 19,050 6488999 3.466 1.000 0 44.41 429 19,050 4420474 2.935 .998 .002

823 34.99 930 32,540 15248791 .411 .659 .341 54.87 593 32,540 9449170 -.870 .192 .192

824 32.65 65 2,122 63220 -1.163 .122 .122 57.35 37 2,122 31977 -1.954 .025 .025

825 34.87 116 4,045 249706 1.200 .885 .115 49.94 81 4,045 170915 .675 .750 .250

826 17.18 1,543 26,503 20303277 -.478 .316 .316 24.61 1,077 26,503 14248460 -.093 .463 .463

827 16.94 616 10,437 3293339 1.053 .854 .146 24.67 423 10,437 2279848 1.169 .879 .121

828 17.25 1,497 25,827 19973109 2.224 .987 .013 24.32 1,062 25,827 13829030 .473 .682 .318

Table 5. Summary of interoccurrence intervals for daily precipitation thresholds of 0.75 and 1.0 inch—Continued

Seq.

no.

Daily precipitation threshold of 0.75 inch and greater Daily precipitation threshold of 1.0 inch and greater

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue
132 Atlas of Interoccurrence Intervals for Selected Thresholds of Daily Precipitation in Texas 

829 15.61 346 5,401 949465 0.520 .699 .301 21.96 246 5,401 682664 0.750 .773 .227

830 31.20 420 13,102 2786579 .454 .675 .325 43.82 299 13,102 1986685 .427 .665 .335

831 22.43 632 14,176 4611228 1.279 .900 .100 32.82 432 14,176 3149226 1.025 .847 .153

832 27.81 63 1,752 51946 -.808 .210 .210 40.74 43 1,752 35268 -.724 .235 .235

833 46.89 35 1,641 27091 -.580 .281 .281 71.35 23 1,641 17140 -.762 .223 .223

834 36.66 112 4,106 235279 .426 .665 .335 60.38 68 4,106 149102 .972 .834 .166

835 16.21 1,144 18,549 10842431 1.283 .900 .100 21.47 864 18,549 8347840 2.126 .983 .017

836 32.82 230 7,548 894623 .805 .790 .210 45.20 167 7,548 642318 .428 .666 .334

837 15.59 766 11,942 4724151 1.576 .942 .058 22.28 536 11,942 3345618 1.819 .966 .034

838 15.12 504 7,618 1970088 1.020 .846 .154 20.87 365 7,618 1465257 1.784 .963 .037

839 18.16 124 2,252 135823 -.525 .300 .300 28.51 79 2,252 85852 -.537 .296 .296

840 25.93 1,406 36,458 26660988 2.613 .996 .004 37.55 971 36,458 18735667 3.157 .999 .001

841 16.88 1,071 18,077 10002076 1.885 .970 .030 23.69 763 18,077 7253236 2.476 .993 .007

842 19.00 986 18,731 9562652 1.933 .973 .027 26.35 711 18,731 6903127 1.694 .955 .045

843 16.87 213 3,594 390561 .515 .697 .303 22.60 159 3,594 295855 .775 .781 .219

844 25.44 690 17,555 6007889 -.365 .358 .358 35.47 495 17,555 4283431 -.545 .293 .293

845 14.06 266 3,740 520896 1.333 .909 .091 19.38 193 3,740 389709 1.920 .973 .027

846 13.75 471 6,477 1569010 1.076 .859 .141 18.35 353 6,477 1174662 .896 .815 .185

847 25.15 713 17,934 6465986 .525 .700 .300 34.62 518 17,934 4558736 -.731 .232 .232

848 27.87 1,032 28,763 15742070 3.376 1.000 0 40.57 709 28,763 10738849 2.453 .993 .007

849 20.56 330 6,785 1132375 .361 .641 .359 27.92 243 6,785 841675 .567 .714 .286

850 39.75 36 1,431 25851 .038 .515 .485 57.24 25 1,431 19027 .552 .709 .291

851 22.81 16 365 3941 2.423 .992 .008 28.08 13 365 3202 2.183 .986 .015

852 14.28 32 457 7883 .765 .778 .222 19.04 24 457 5578 .145 .558 .442

853 21.08 13 274 1612 -.593 .277 .277 39.14 7 274 636 -1.544 .061 .061

854 43.55 434 18,899 4412777 2.742 .997 .003 62.79 301 18,899 3054137 2.217 .987 .013

855 22.02 253 5,570 727538 .897 .815 .185 31.47 177 5,570 513282 .951 .829 .171

856 45.19 414 18,709 3848100 -.224 .411 .411 73.08 256 18,709 2381651 -.152 .440 .440

857 32.62 279 9,100 1404751 3.084 .999 .001 46.67 195 9,100 984016 2.638 .996 .004

858 35.27 300 10,580 1629225 .798 .788 .212 55.68 190 10,580 1077669 1.724 .958 .042

859 38.23 245 9,367 1170692 .549 .708 .292 56.09 167 9,367 798635 .472 .681 .319

860 43.46 28 1,217 13854 -1.713 .043 .043 110.64 11 1,217 6158 -.460 .323 .323

861 40.35 358 14,445 2553289 -.410 .341 .341 56.87 254 14,445 1791835 -.642 .260 .260

862 18.35 416 7,632 1630372 .955 .830 .170 24.70 309 7,632 1227069 1.238 .892 .108

863 19.36 22 426 5466 1.352 .912 .088 32.77 13 426 3310 1.220 .889 .111

864 70.04 258 18,069 2331953 .013 .505 .495 106.92 169 18,069 1506875 -.294 .384 .384

865 46.84 50 2,342 60089 .322 .626 .374 80.76 29 2,342 34482 .144 .557 .443

866 46.12 59 2,721 84382 .682 .752 .248 75.58 36 2,721 49391 .088 .535 .465

867 31.55 504 15,899 4238229 2.249 .988 .012 44.29 359 15,899 3021937 1.933 .973 .027

868 30.98 702 21,746 7976208 2.064 .981 .019 45.98 473 21,746 5473817 2.424 .992 .008

869 50.11 368 18,440 3204125 -1.849 .032 .032 81.59 226 18,440 1919055 -2.058 .020 .020

870 14.58 108 1,575 99334 3.023 .999 .001 21.00 75 1,575 67883 2.240 .987 .013

871 126.00 2 252 299 .457 .676 .324 252.00 1 252 211 1.168 .879 .121

872 24.30 20 486 4916 .089 .536 .464 37.39 13 486 3503 .680 .752 .248

873 14.44 1,625 23,470 19081853 .046 .518 .482 19.62 1,196 23,470 13892289 -.609 .271 .271

874 13.41 427 5,724 1164629 -1.682 .046 .046 17.89 320 5,724 893461 -.757 .225 .225

875 16.72 29 485 6754 -.369 .356 .356 20.21 24 485 5564 -.373 .355 .355

876 -- -- -- -- -- -- -- -- -- -- -- -- -- --

877 43.00 10 430 2633 1.231 .891 .109 86.00 5 430 1174 .357 .639 .361

878 17.29 906 15,666 6915822 -1.329 .092 .092 24.21 647 15,666 4831468 -2.056 .020 .020

879 47.91 386 18,493 3639603 .672 .749 .251 70.32 263 18,493 2519726 1.015 .845 .155

880 111.50 2 223 171 -.571 .284 .284 111.50 2 223 171 -.571 .284 .284

Table 5. Summary of interoccurrence intervals for daily precipitation thresholds of 0.75 and 1.0 inch—Continued

Seq.

no.

Daily precipitation threshold of 0.75 inch and greater Daily precipitation threshold of 1.0 inch and greater

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue
Table 5 133

881 37.64 494 18,595 4675673 0.693 .756 .244 57.93 321 18,595 3045734 0.637 .738 .262

882 32.04 57 1,826 46850 -1.304 .096 .096 46.82 39 1,826 31290 -1.311 .095 .095

883 33.85 322 10,901 1716686 -.680 .248 .248 55.06 198 10,901 1082691 .079 .531 .469

884 40.45 337 13,631 2255954 -.566 .286 .286 60.85 224 13,631 1471064 -.944 .173 .173

885 35.74 831 29,698 12568619 .927 .823 .177 54.49 545 29,698 8337617 1.224 .889 .111

886 20.72 1,031 21,366 11097552 .421 .663 .337 28.68 745 21,366 7981120 .132 .553 .447

887 19.16 1,309 25,079 17428621 3.873 1.000 0 27.03 928 25,079 12358115 3.271 .999 .001

888 25.41 745 18,929 7372999 2.159 .985 .015 39.27 482 18,929 4904405 2.855 .998 .002

889 45.91 299 13,726 2239128 2.731 .997 .003 75.42 182 13,726 1345906 1.812 .965 .035

890 43.33 302 13,085 1920649 -.841 .200 .200 69.60 188 13,085 1167269 -1.211 .113 .113

891 51.99 349 18,143 3322902 1.604 .946 .054 71.43 254 18,143 2368376 .769 .779 .221

892 50.53 143 7,226 510900 -.231 .409 .409 66.91 108 7,226 387318 -.133 .447 .447

893 42.69 631 26,939 8254493 -1.253 .105 .105 66.03 408 26,939 5182512 -1.993 .023 .023

894 25.60 220 5,631 640053 .856 .804 .196 36.80 153 5,631 447943 .854 .803 .197

895 75.87 225 17,071 1988496 .920 .821 .179 143.45 119 17,071 1059488 .814 .792 .208

896 17.88 2,000 35,755 37085619 2.883 .998 .002 26.08 1,371 35,755 25241555 1.914 .972 .028

897 23.00 8 184 720 -.107 .458 .458 36.80 5 184 506 .387 .651 .349

898 14.42 84 1,211 51662 .250 .599 .401 19.85 61 1,211 38609 .613 .730 .270

899 29.00 2 58 44 -.591 .277 .277 29.00 2 58 44 -.591 .277 .277

900 22.52 68 1,531 55511 .949 .829 .171 33.28 46 1,531 32406 -.936 .175 .175

901 35.80 951 34,050 16766017 1.898 .971 .029 53.37 638 34,050 11318113 1.837 .967 .033

902 33.06 34 1,124 20776 .882 .811 .189 51.09 22 1,124 13192 .544 .707 .293

903 101.92 248 25,276 3230972 .842 .800 .200 191.49 132 25,276 1786764 1.414 .921 .079

904 198.00 2 396 564 1.039 .851 .149 -- -- -- -- -- -- --

905 77.33 215 16,626 1785877 -.020 .492 .492 116.27 143 16,626 1151767 -.645 .260 .260

906 43.63 725 31,631 11514491 .196 .578 .422 72.22 438 31,631 7056694 .678 .751 .249

907 -- -- -- -- -- -- -- -- -- -- -- -- -- --

908 47.55 416 19,782 4306022 1.643 .950 .050 75.50 262 19,782 2670311 .853 .803 .197

909 41.55 202 8,392 864314 .486 .686 .314 67.14 125 8,392 585650 2.258 .988 .012

910 120.09 59 7,085 213717 .300 .618 .382 214.70 33 7,085 135024 1.542 .938 .062

911 139.80 15 2,097 16030 .129 .551 .449 262.13 8 2,097 9121 .428 .666 .334

912 20.13 15 302 1635 -1.866 .031 .031 21.57 14 302 1522 -1.815 .035 .035

913 28.42 226 6,422 773230 1.706 .956 .044 40.39 159 6,422 559890 2.111 .983 .017

914 21.95 165 3,622 291705 -.529 .298 .298 36.59 99 3,622 179807 .050 .520 .480

915 19.39 1,735 33,649 31506167 5.723 0 0 26.75 1,258 33,649 23029175 5.410 0 0

916 19.78 967 19,131 9918218 3.892 1.000 0 26.28 728 19,131 7756241 5.319 0 0

917 60.23 128 7,709 405934 -3.473 0 0 105.60 73 7,709 226941 -2.863 .002 .002

918 14.49 611 8,856 2829840 1.968 .975 .025 19.09 464 8,856 2155596 1.834 .967 .033

919 32.89 298 9,801 1463782 .070 .528 .472 46.67 210 9,801 1087163 1.416 .922 .078

920 17.26 1,107 19,104 10856603 1.540 .938 .062 24.56 778 19,104 7601365 1.105 .865 .135

921 26.63 164 4,368 395415 2.306 .989 .011 40.44 108 4,368 270085 2.611 .995 .005

922 54.67 416 22,744 4884173 1.146 .874 .126 89.54 254 22,744 2932783 .423 .664 .336

923 46.88 713 33,427 11224622 -2.686 .004 .004 73.63 454 33,427 7239608 -1.694 .045 .045

924 63.90 10 639 2448 -1.281 .100 .100 106.50 6 639 1897 -.044 .482 .482

925 77.87 54 4,205 134035 2.298 .989 .011 113.65 37 4,205 95697 2.425 .992 .008

926 29.26 19 556 6122 1.201 .885 .115 39.71 14 556 4438 .909 .818 .182

927 23.83 186 4,433 403934 -.478 .317 .317 34.63 128 4,433 289978 .433 .667 .333

928 42.59 179 7,623 769917 2.977 .999 .001 71.92 106 7,623 440691 1.619 .947 .053

929 20.90 752 15,716 5774203 -1.085 .139 .139 28.32 555 15,716 4313960 -.442 .329 .329

930 48.97 186 9,108 893586 1.298 .903 .097 69.53 131 9,108 626656 1.000 .841 .159

931 33.40 145 4,843 358699 .450 .674 .326 43.63 111 4,843 282763 .949 .829 .171

932 26.90 121 3,255 191169 -.557 .289 .289 50.08 65 3,255 99522 -.827 .204 .204

Table 5. Summary of interoccurrence intervals for daily precipitation thresholds of 0.75 and 1.0 inch—Continued

Seq.

no.

Daily precipitation threshold of 0.75 inch and greater Daily precipitation threshold of 1.0 inch and greater

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue
134 Atlas of Interoccurrence Intervals for Selected Thresholds of Daily Precipitation in Texas 

933 -- -- -- -- -- -- -- -- -- -- -- -- -- --

934 26.29 211 5,547 591162 0.256 .601 .399 35.33 157 5,547 447564 0.604 .727 .273

935 15.27 1,290 19,694 13288481 2.869 .998 .002 21.04 936 19,694 9625071 2.347 .991 .009

936 14.48 657 9,510 3094711 -.417 .338 .338 20.23 470 9,510 2224195 -.179 .429 .429

937 15.73 567 8,920 2496735 -.523 .300 .300 21.14 422 8,920 1813100 -1.305 .096 .096

938 35.01 723 25,311 9510669 1.836 .967 .033 48.30 524 25,311 6868416 1.417 .922 .078

939 21.98 983 21,605 10835039 1.106 .865 .135 30.22 715 21,605 7971699 1.487 .931 .069

940 35.81 444 15,898 3593282 .661 .746 .254 47.60 334 15,898 2746843 1.095 .863 .137

941 24.56 670 16,452 5167374 -2.799 .003 .003 33.85 486 16,452 3813468 -1.761 .039 .039

942 32.91 399 13,131 2604661 -.198 .422 .422 51.90 253 13,131 1617805 -.718 .237 .237

943 43.18 756 32,647 12444161 .400 .655 .345 67.59 483 32,647 8085643 .972 .834 .166

944 19.66 292 5,740 856977 .669 .748 .252 28.56 201 5,740 562168 -.626 .266 .266

945 32.66 654 21,362 7307457 2.042 .979 .021 45.16 473 21,362 5262263 1.567 .941 .059

946 21.03 467 9,820 2300671 .126 .550 .450 29.85 329 9,820 1601034 -.279 .390 .390

947 30.36 454 13,784 3344086 2.537 .994 .006 44.47 310 13,784 2264557 1.828 .966 .034

948 36.85 33 1,216 20852 .391 .652 .348 64.00 19 1,216 11977 .278 .609 .391

949 113.29 234 26,509 3330847 1.959 .975 .025 207.10 128 26,509 1789450 1.073 .858 .142

950 -- -- -- -- -- -- -- -- -- -- -- -- -- --

951 18.85 658 12,405 3967543 -1.238 .108 .108 26.79 463 12,405 2775577 -1.248 .106 .106

952 22.71 217 4,929 582721 2.286 .989 .011 32.86 150 4,929 403717 1.953 .975 .025

953 26.62 527 14,026 3774330 .844 .801 .199 39.40 356 14,026 2600365 1.358 .913 .087

954 22.85 303 6,922 1141251 2.661 .996 .004 32.35 214 6,922 800037 2.032 .979 .021

955 33.29 993 33,055 16464841 .176 .570 .430 49.48 668 33,055 10871666 -.684 .247 .247

956 34.26 1,014 34,736 17666559 .174 .569 .431 50.05 694 34,736 11976611 -.291 .386 .386

957 20.11 213 4,283 469014 .714 .762 .238 27.63 155 4,283 333139 .078 .531 .469

958 42.66 294 12,543 1893510 .800 .788 .212 65.33 192 12,543 1299918 1.909 .972 .028

959 18.46 749 13,823 5080482 -.881 .189 .189 26.18 528 13,823 3547582 -1.109 .134 .134

960 16.62 47 781 20352 1.293 .902 .098 22.97 34 781 14807 1.164 .878 .122

961 27.63 727 20,090 7208711 -.601 .274 .274 38.78 518 20,090 5224344 .159 .563 .437

962 89.88 8 719 3427 .939 .826 .174 179.75 4 719 1653 .518 .698 .302

963 38.03 30 1,141 15443 -.927 .177 .177 63.39 18 1,141 7403 -2.051 .020 .020

964 37.32 54 2,015 51400 -.703 .241 .241 54.46 37 2,015 35850 -.404 .343 .343

965 29.04 351 10,194 1798450 .171 .568 .432 43.38 235 10,194 1184859 -.287 .387 .387

966 57.35 155 8,889 693737 .152 .560 .440 84.66 105 8,889 463132 -.135 .446 .446

967 56.79 89 5,054 206431 -1.342 .090 .090 99.10 51 5,054 130301 .137 .554 .446

968 20.04 79 1,583 67179 1.145 .874 .126 28.78 55 1,583 45291 .519 .698 .302

969 21.73 56 1,217 37868 1.442 .925 .075 29.68 41 1,217 27851 1.290 .901 .099

970 34.14 959 32,743 15761568 .209 .583 .417 48.22 679 32,743 11312440 .797 .787 .213

971 20.75 83 1,722 73987 .557 .711 .289 30.75 56 1,722 51102 .776 .781 .219

972 31.24 593 18,526 5916306 3.251 .999 .001 45.97 403 18,526 3960421 2.118 .983 .017

973 98.69 198 19,541 2073829 1.755 .960 .040 152.66 128 19,541 1371487 1.894 .971 .029

974 20.90 534 11,161 3032709 .708 .760 .240 30.50 366 11,161 2092936 .819 .794 .206

975 22.19 559 12,404 3465577 -.016 .494 .494 30.18 411 12,404 2585200 .498 .691 .309

976 24.00 37 888 17947 .974 .835 .165 29.60 30 888 13696 .268 .606 .394

977 18.60 5 93 251 .308 .621 .379 31.00 3 93 135 -.097 .461 .461

978 24.11 554 13,354 3944102 2.701 .997 .003 33.81 395 13,354 2803559 2.169 .985 .015

979 23.52 243 5,715 695151 .030 .512 .488 32.66 175 5,715 510205 .465 .679 .321

980 23.66 151 3,573 265213 -.359 .360 .360 30.28 118 3,573 199951 -.969 .166 .166

981 15.00 1 15 15 1.732 .958 .042 15.00 1 15 15 1.732 .958 .042

982 22.71 17 386 3452 .372 .645 .355 27.57 14 386 2718 .038 .515 .485

983 16.81 622 10,455 3340484 1.182 .881 .119 25.82 405 10,455 2191099 1.218 .888 .112

984 36.43 97 3,534 178979 .754 .775 .225 52.75 67 3,534 112348 -.723 .235 .235

Table 5. Summary of interoccurrence intervals for daily precipitation thresholds of 0.75 and 1.0 inch—Continued

Seq.

no.

Daily precipitation threshold of 0.75 inch and greater Daily precipitation threshold of 1.0 inch and greater

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue
Table 5 135

985 26.93 45 1,212 26760 -0.217 .414 .414 35.65 34 1,212 20131 -0.232 .408 .408

986 27.94 124 3,465 250027 3.160 .999 .001 36.86 94 3,465 202786 4.118 1.000 0

987 34.15 658 22,473 7291417 -.614 .270 .270 49.94 450 22,473 4914806 -1.029 .152 .152

988 20.22 116 2,346 133117 -.405 .343 .343 27.93 84 2,346 98091 -.071 .472 .472

989 18.06 895 16,159 7424104 1.383 .917 .083 25.94 623 16,159 5145913 .965 .833 .167

990 22.01 847 18,639 8355440 2.949 .998 .002 30.21 617 18,639 6071672 2.406 .992 .008

991 28.93 642 18,574 6085950 .911 .819 .181 42.70 435 18,574 4344220 2.722 .997 .003

992 18.42 1,085 19,989 11607926 4.019 1.000 0 26.34 759 19,989 8127519 3.408 1.000 0

993 36.03 38 1,369 29923 1.606 .946 .054 54.76 25 1,369 21131 2.034 .979 .021

994 31.68 195 6,177 628241 1.044 .852 .148 43.50 142 6,177 453897 .722 .765 .235

995 26.61 619 16,470 5312674 1.819 .966 .034 37.52 439 16,470 3799635 1.852 .968 .032

996 48.41 596 28,850 9101362 2.479 .993 .007 67.09 430 28,850 6637811 2.519 .994 .006

997 28.79 957 27,555 13601234 1.691 .955 .045 40.46 681 27,555 9792562 1.976 .976 .024

998 30.03 710 21,324 7855829 1.743 .959 .041 43.52 490 21,324 5465064 1.766 .961 .039

999 28.73 127 3,649 214622 -1.440 .075 .075 40.10 91 3,649 149238 -1.671 .047 .047

1000 20.38 442 9,008 2055012 1.175 .880 .120 29.73 303 9,008 1438469 1.630 .948 .052

1001 22.92 860 19,714 8993437 3.094 .999 .001 32.80 601 19,714 6351730 3.065 .999 .001

1002 7.00 2 14 18 .700 .758 .242 14.00 1 14 6 -.247 .402 .402

1003 40.71 500 20,356 5391799 2.305 .989 .011 63.22 322 20,356 3517026 2.273 .989 .012

1004 29.46 692 20,384 7303890 1.622 .948 .052 39.05 522 20,384 5447926 .950 .829 .171

1005 35.82 596 21,346 6276111 -.565 .286 .286 53.23 401 21,346 4061282 -1.772 .038 .038

1006 21.12 134 2,830 181882 -.817 .207 .207 30.76 92 2,830 119844 -1.319 .094 .094

1007 27.47 308 8,461 1234613 -1.595 .055 .055 35.70 237 8,461 897867 -2.786 .003 .003

1008 22.56 616 13,894 4232818 -.468 .320 .320 33.40 416 13,894 2868437 -.263 .396 .396

1009 17.37 721 12,527 4580215 .662 .746 .254 24.66 508 12,527 3276959 1.167 .878 .122

1010 24.97 627 15,655 4727091 -1.597 .055 .055 33.74 464 15,655 3505659 -1.297 .097 .097

1011 36.70 556 20,404 5699440 .195 .577 .423 51.92 393 20,404 4080244 .607 .728 .272

1012 37.89 79 2,993 124817 .859 .805 .195 59.86 50 2,993 81921 1.162 .877 .123

1013 35.70 306 10,925 1656303 -.276 .391 .391 53.29 205 10,925 1088879 -.685 .247 .247

1014 29.65 79 2,342 95641 .521 .699 .301 45.04 52 2,342 62260 .281 .611 .389

1015 61.00 7 427 1054 -1.351 .088 .088 85.40 5 427 853 -.778 .218 .218

1016 20.68 969 20,037 9678398 -.164 .435 .435 30.27 662 20,037 6577240 -.370 .356 .356

1017 24.57 76 1,867 81895 2.330 .990 .010 36.61 51 1,867 58097 2.725 .997 .003

1018 15.04 161 2,421 178968 -1.796 .036 .036 19.52 124 2,421 137435 -1.628 .052 .052

1019 43.58 185 8,062 793656 1.514 .935 .065 76.06 106 8,062 459382 1.340 .910 .090

1020 43.29 136 5,888 435180 1.755 .960 .040 66.91 88 5,888 270194 .698 .757 .243

1021 39.56 613 24,253 7511446 .449 .673 .327 60.03 404 24,253 4990861 .652 .743 .257

1022 19.59 504 9,875 2484157 -.068 .473 .473 28.46 347 9,875 1681763 -.594 .276 .276

1023 21.53 313 6,740 1015292 -1.148 .126 .126 29.05 232 6,740 749017 -1.108 .134 .134

1024 22.64 518 11,727 3064586 .354 .638 .362 31.27 375 11,727 2294421 1.458 .928 .072

1025 32.84 86 2,824 110467 -1.450 .074 .074 48.69 58 2,824 78057 -.618 .268 .268

1026 21.12 905 19,114 8822182 1.043 .851 .149 30.73 622 19,114 6211280 1.939 .974 .026

1027 32.65 207 6,758 704173 .168 .567 .433 48.27 140 6,758 484445 .493 .689 .311

1028 38.12 718 27,372 10292748 2.202 .986 .014 58.12 471 27,372 6877934 2.518 .994 .006

1029 25.96 599 15,548 4916063 2.362 .991 .009 38.77 401 15,548 3308429 2.126 .983 .017

1030 23.11 530 12,246 3312098 .822 .794 .206 34.21 358 12,246 2279170 1.303 .904 .096

1031 63.45 40 2,538 42764 -1.726 .042 .042 94.00 27 2,538 30079 -1.099 .136 .136

1032 29.46 1,237 36,443 22488081 -.140 .444 .444 41.84 871 36,443 15925233 .175 .569 .431

1033 16.16 1,326 21,434 14621675 1.824 .966 .034 22.63 947 21,434 10550003 2.106 .982 .018

1034 42.43 51 2,164 53011 -.487 .313 .313 56.95 38 2,164 42086 .252 .599 .401

1035 33.84 999 33,805 17111557 .733 .768 .232 48.36 699 33,805 12037811 .864 .806 .194

1036 11.91 45 536 12195 .130 .552 .448 14.11 38 536 10368 .193 .577 .423

Table 5. Summary of interoccurrence intervals for daily precipitation thresholds of 0.75 and 1.0 inch—Continued

Seq.

no.

Daily precipitation threshold of 0.75 inch and greater Daily precipitation threshold of 1.0 inch and greater

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue
136 Atlas of Interoccurrence Intervals for Selected Thresholds of Daily Precipitation in Texas 

1037 26.63 16 426 2557 -1.730 .042 .042 30.43 14 426 1739 -2.701 .003 .003

1038 25.90 134 3,471 250585 1.554 .940 .060 36.93 94 3,471 169418 .647 .741 .259

1039 162.84 43 7,002 175332 1.870 .969 .031 318.27 22 7,002 93391 1.727 .958 .042

1040 152.69 45 6,871 150229 -.328 .371 .371 229.03 30 6,871 102807 -.024 .491 .491

1041 166.67 21 3,500 35611 -.246 .403 .403 318.18 11 3,500 16867 -.711 .239 .239

1042 13.32 932 12,414 5739574 -.415 .339 .339 18.31 678 12,414 4235911 .295 .616 .384

1043 67.29 7 471 744 -2.514 .006 .006 94.20 5 471 436 -2.439 .007 .007

1044 43.79 187 8,188 843395 2.408 .992 .008 67.12 122 8,188 563061 2.436 .993 .007

1045 47.84 418 19,999 4478145 2.528 .994 .006 72.46 276 19,999 2960951 2.097 .982 .018

1046 29.41 58 1,706 51947 .659 .745 .255 36.30 47 1,706 45670 1.652 .951 .049

1047 29.33 689 20,211 7463533 3.270 .999 .001 42.91 471 20,211 5067747 2.433 .993 .007

1048 32.03 375 12,010 2279094 .405 .657 .343 45.67 263 12,010 1587582 .147 .558 .442

1049 27.98 175 4,897 437192 .466 .679 .321 39.81 123 4,897 295058 -.390 .348 .348

1050 14.96 805 12,043 5134164 2.908 .998 .002 20.17 597 12,043 3726801 1.554 .940 .060

1051 33.39 535 17,865 4720704 -.488 .313 .313 45.34 394 17,865 3569250 .487 .687 .313

1052 42.59 17 724 5417 -.855 .196 .196 65.82 11 724 3328 -.944 .173 .173

1053 14.70 71 1,044 35952 -.437 .331 .331 19.70 53 1,044 26586 -.492 .311 .311

1054 30.50 2 61 24 -1.486 .069 .069 61.00 1 61 21 -.540 .295 .295

1055 17.06 196 3,344 345115 1.288 .901 .099 26.54 126 3,344 219956 .857 .804 .196

1056 41.22 51 2,102 59375 1.332 .909 .091 55.32 38 2,102 43374 .919 .821 .179

1057 63.50 8 508 1869 -.393 .347 .347 84.67 6 508 1449 -.209 .417 .417

1058 25.12 1,403 35,247 25156200 1.129 .871 .129 35.25 1,000 35,247 18085362 1.435 .924 .076

1059 32.50 22 715 6565 -1.343 .090 .090 55.00 13 715 3230 -1.905 .028 .028

1060 32.05 756 24,233 9596743 2.270 .988 .012 47.99 505 24,233 6393207 1.745 .960 .040

1061 34.74 19 660 6023 -.297 .383 .383 41.25 16 660 5238 -.055 .478 .478

1062 56.22 37 2,080 32658 -1.594 .055 .055 86.67 24 2,080 18869 -2.071 .019 .019

1063 74.13 322 23,869 3951468 .878 .810 .190 114.76 208 23,869 2518225 .361 .641 .359

1064 72.88 17 1,239 11408 .594 .724 .276 103.25 12 1,239 8452 .822 .794 .206

1065 32.46 187 6,070 567023 -.022 .491 .491 49.75 122 6,070 362071 -.424 .336 .336

1066 24.11 461 11,113 2627238 .954 .830 .170 35.28 315 11,113 1778623 .498 .691 .309

1067 27.79 33 917 16661 1.007 .843 .157 36.68 25 917 12757 .978 .836 .164

1068 34.10 21 716 7183 -.354 .362 .362 44.75 16 716 5514 -.259 .398 .398

1069 43.34 125 5,418 319033 -1.120 .131 .131 53.12 102 5,418 271678 -.294 .384 .384

1070 31.82 1,107 35,225 19343838 -.453 .325 .325 45.10 781 35,225 13455605 -1.055 .146 .146

1071 22.72 864 19,631 8784398 1.824 .966 .034 32.88 597 19,631 6086929 1.640 .949 .051

1072 26.90 62 1,668 49466 -.591 .277 .277 37.07 45 1,668 35171 -.730 .233 .233

1073 -- -- -- -- -- -- -- -- -- -- -- -- -- --

1074 20.11 1,497 30,105 22846017 .929 .824 .176 28.14 1,070 30,105 16173364 .236 .593 .407

1075 34.07 76 2,589 102592 .646 .741 .259 53.94 48 2,589 59474 -.514 .304 .304

1076 28.51 633 18,047 5727330 .118 .547 .453 41.78 432 18,047 3859926 -.353 .362 .362

1077 25.85 133 3,438 237781 .800 .788 .212 36.19 95 3,438 167558 .440 .670 .330

1078 58.04 474 27,513 6558858 .221 .588 .412 90.21 305 27,513 4350930 1.119 .868 .132

1079 32.26 970 31,290 15362475 .664 .747 .253 48.97 639 31,290 10153176 .683 .753 .247

1080 34.57 14 484 3997 1.165 .878 .122 48.40 10 484 2864 1.005 .842 .158

1081 40.29 527 21,232 5495408 -.705 .240 .240 61.54 345 21,232 3717048 .479 .684 .316

1082 41.25 332 13,695 2388340 1.596 .945 .055 60.60 226 13,695 1618577 1.195 .884 .116

1083 58.23 265 15,430 2084867 .557 .711 .289 92.95 166 15,430 1263541 -.299 .383 .383

1084 18.72 65 1,217 39564 .004 .502 .498 27.04 45 1,217 27057 -.138 .445 .445

1085 20.22 1,797 36,335 32943675 .667 .748 .252 29.52 1,231 36,335 22635761 .738 .770 .230

1086 46.75 108 5,049 251769 -1.378 .084 .084 63.91 79 5,049 176767 -1.750 .040 .040

1087 106.44 132 14,050 899796 -.590 .278 .278 182.47 77 14,050 513030 -.784 .217 .217

1088 15.01 150 2,252 171107 .277 .609 .391 19.75 114 2,252 134013 .814 .792 .208

Table 5. Summary of interoccurrence intervals for daily precipitation thresholds of 0.75 and 1.0 inch—Continued

Seq.

no.

Daily precipitation threshold of 0.75 inch and greater Daily precipitation threshold of 1.0 inch and greater

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue
Table 5 137

1089 40.90 29 1,186 15934 -0.685 .247 .247 59.30 20 1,186 11345 -0.336 .368 .368

1090 32.32 315 10,180 1564067 -.753 .226 .226 49.90 204 10,180 1018058 -.484 .314 .314

1091 43.58 452 19,700 4467686 .128 .551 .449 71.64 275 19,700 2697469 -.120 .452 .452

1092 11.18 11 123 379 -2.526 .006 .006 12.30 10 123 285 -2.939 .002 .002

1093 16.24 293 4,757 746990 2.131 .983 .017 23.67 201 4,757 511013 1.692 .955 .045

1094 27.25 947 25,807 12779459 2.442 .993 .007 38.18 676 25,807 9267621 2.813 .998 .002

1095 20.39 97 1,978 91989 -.701 .242 .242 28.67 69 1,978 63661 -.966 .167 .167

1096 48.74 392 19,104 3873492 1.182 .881 .119 75.21 254 19,104 2504542 .891 .814 .186

1097 21.77 874 19,028 9134635 5.046 0 0 30.84 617 19,028 6374564 3.697 1.000 0

1098 29.61 499 14,774 3711226 .264 .604 .396 43.45 340 14,774 2495189 -.208 .417 .417

1099 103.00 2 206 154 -.618 .268 .268 -- -- -- -- -- -- --

1100 26.11 108 2,820 142836 -1.116 .132 .132 39.72 71 2,820 95796 -.629 .265 .265

1101 22.34 1,307 29,198 19386346 1.002 .842 .158 31.98 913 29,198 13646907 1.249 .894 .106

1102 40.62 777 31,561 12009573 -.992 .161 .161 65.89 479 31,561 7396357 -.815 .208 .208

1103 177.39 59 10,466 301673 -.305 .380 .380 337.61 31 10,466 169956 .460 .677 .323

1104 23.53 332 7,812 1357346 1.474 .930 .070 32.28 242 7,812 1013616 1.949 .974 .026

1105 21.78 608 13,243 4177929 1.613 .947 .053 30.87 429 13,243 2948992 1.369 .914 .086

1106 40.67 553 22,491 6215129 -.024 .490 .490 60.95 369 22,491 4126469 -.185 .426 .426

1107 43.51 37 1,610 25571 -1.491 .068 .068 59.63 27 1,610 19714 -.837 .201 .201

1108 -- -- -- -- -- -- -- -- -- -- -- -- -- --

1109 32.95 106 3,493 169607 -1.495 .067 .067 51.37 68 3,493 112124 -.798 .212 .212

1110 33.75 104 3,510 161449 -2.039 .021 .021 44.43 79 3,510 123161 -1.719 .043 .043

1111 53.62 42 2,252 40915 -1.514 .065 .065 86.62 26 2,252 23940 -1.610 .054 .054

1112 18.32 656 12,016 4108993 1.888 .970 .030 25.35 474 12,016 3000079 2.017 .978 .022

1113 44.76 659 29,498 9527094 -.881 .189 .189 72.12 409 29,498 5910921 -.705 .240 .240

1114 25.63 473 12,124 2818241 -.645 .260 .260 36.74 330 12,124 1948151 -.823 .205 .205

1115 41.52 140 5,813 422448 .783 .783 .217 62.51 93 5,813 282010 .723 .765 .235

1116 18.39 79 1,453 55509 -.506 .307 .307 25.05 58 1,453 40708 -.447 .327 .327

1117 26.26 599 15,727 4764742 .491 .688 .312 36.07 436 15,727 3420610 -.083 .467 .467

1118 27.59 29 800 12366 .616 .731 .269 38.10 21 800 8048 -.333 .370 .370

1119 26.62 285 7,586 1043373 -1.018 .154 .154 40.35 188 7,586 679965 -1.103 .135 .135

1120 42.03 582 24,462 7138860 .120 .548 .452 69.10 354 24,462 4321767 -.060 .476 .476

1121 32.15 923 29,675 13701865 .026 .511 .489 49.21 603 29,675 8768291 -.850 .198 .198

1122 32.94 31 1,021 14056 -1.078 .141 .141 44.39 23 1,021 8917 -1.998 .023 .023

1123 28.79 792 22,804 9162882 .715 .763 .237 44.19 516 22,804 5746719 -.914 .180 .180

1124 23.24 59 1,371 35017 -1.785 .037 .037 42.84 32 1,371 20840 -.490 .312 .312

1125 30.32 93 2,820 134834 .472 .681 .319 47.00 60 2,820 87655 .485 .686 .314

1126 47.69 81 3,863 155634 -.082 .467 .467 64.38 60 3,863 121229 .618 .732 .268

1127 41.78 639 26,696 7971135 -2.866 .002 .002 63.87 418 26,696 5207068 -2.364 .009 .009

1128 43.82 220 9,641 1066090 .135 .554 .446 65.59 147 9,641 679062 -.876 .191 .191

1129 63.12 57 3,598 107537 .637 .738 .262 94.68 38 3,598 74947 1.029 .848 .152

1130 94.38 8 755 2586 -.704 .241 .241 125.83 6 755 1421 -1.581 .057 .057

1131 23.88 580 13,853 4217690 2.080 .981 .019 34.38 403 13,853 2999915 2.598 .995 .005

1132 53.54 13 696 3819 -.973 .165 .165 99.43 7 696 1641 -1.496 .067 .067

1133 26.30 384 10,098 1921181 -.309 .379 .379 36.85 274 10,098 1350842 -.675 .250 .250

1134 52.69 13 685 4558 .148 .559 .441 85.63 8 685 2780 .072 .529 .471

1135 14.61 54 789 18501 -1.674 .047 .047 18.79 42 789 14689 -1.274 .101 .101

1136 54.23 514 27,875 7303219 .764 .777 .223 87.38 319 27,875 4406333 -.276 .391 .391

1137 28.62 669 19,145 6566155 1.134 .872 .128 41.89 457 19,145 4504849 1.102 .865 .135

1138 68.58 36 2,469 47824 .791 .785 .215 137.17 18 2,469 22535 .104 .541 .459

1139 111.32 28 3,117 32712 -2.295 .011 .011 207.80 15 3,117 18052 -1.528 .063 .063

1140 41.56 268 11,137 1445480 -.891 .187 .187 62.92 177 11,137 944577 -.960 .169 .169

Table 5. Summary of interoccurrence intervals for daily precipitation thresholds of 0.75 and 1.0 inch—Continued

Seq.

no.

Daily precipitation threshold of 0.75 inch and greater Daily precipitation threshold of 1.0 inch and greater

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue
138 Atlas of Interoccurrence Intervals for Selected Thresholds of Daily Precipitation in Texas 

1141 18.10 1,103 19,965 11502752 2.571 .995 .005 25.53 782 19,965 8354266 3.400 1.000 0

1142 17.61 1,858 32,715 30899306 1.246 .894 .107 25.28 1,294 32,715 21572601 1.195 .884 .116

1143 59.70 151 9,015 688094 .233 .592 .408 96.94 93 9,015 404712 -.577 .282 .282

1144 34.80 69 2,401 87381 .790 .785 .215 46.17 52 2,401 64420 .399 .655 .345

1145 62.13 23 1,429 22071 2.850 .998 .002 95.27 15 1,429 13936 2.015 .978 .022

1146 49.12 542 26,623 7177519 -.209 .417 .417 75.21 354 26,623 4693628 -.129 .449 .449

1147 38.09 163 6,208 523334 .760 .776 .224 53.98 115 6,208 361393 .231 .591 .409

1148 48.87 266 13,000 1723852 -.084 .466 .466 80.75 161 13,000 1032806 -.288 .387 .387

1149 28.98 417 12,084 2629348 1.542 .938 .062 40.96 295 12,084 1797283 .249 .598 .402

1150 52.11 258 13,443 1782189 .771 .779 .221 81.97 164 13,443 1120483 .365 .643 .357

1151 23.31 49 1,142 26235 -.756 .225 .225 38.07 30 1,142 14592 -1.406 .080 .080

1152 24.28 1,090 26,466 14840253 1.650 .951 .049 35.10 754 26,466 10224402 1.176 .880 .120

1153 15.71 31 487 7336 -.272 .393 .393 21.17 23 487 5429 -.254 .400 .400

1154 29.98 435 13,041 2823204 -.168 .433 .433 43.62 299 13,041 1911278 -.589 .278 .278

1155 19.84 69 1,369 40572 -2.028 .021 .021 29.13 47 1,369 29412 -1.019 .154 .154

1156 27.87 467 13,013 3120984 1.016 .845 .155 39.55 329 13,013 2209198 1.006 .843 .157

1157 33.55 538 18,047 5057275 1.677 .953 .047 54.36 332 18,047 3124041 1.351 .912 .088

1158 18.27 195 3,562 359751 .868 .807 .193 25.09 142 3,562 265307 1.012 .844 .156

1159 23.90 1,542 36,849 28745036 .801 .788 .212 34.73 1,061 36,849 19662402 .329 .629 .371

1160 34.17 41 1,401 31990 1.263 .897 .103 48.31 29 1,401 22276 .901 .816 .184

1161 37.39 153 5,720 447142 .468 .680 .320 57.78 99 5,720 296052 .786 .784 .216

1162 110.00 11 1,210 6839 .159 .563 .437 403.33 3 1,210 2734 1.519 .936 .064

1163 143.64 22 3,160 31664 -.724 .235 .235 210.67 15 3,160 22969 -.207 .418 .418

1164 19.86 965 19,160 9383742 .809 .791 .209 27.81 689 19,160 6772023 1.181 .881 .119

1165 42.09 236 9,934 1234330 1.410 .921 .079 60.21 165 9,934 871861 1.420 .922 .078

1166 15.57 770 11,989 4825046 2.179 .985 .015 22.28 538 11,989 3384776 1.990 .977 .023

1167 18.20 371 6,751 1283796 .839 .799 .201 25.87 261 6,751 909645 .910 .818 .182

1168 46.26 54 2,498 66050 -.263 .396 .396 55.51 45 2,498 57471 .262 .603 .397

1169 104.08 12 1,249 7798 .243 .596 .404 156.13 8 1,249 4181 -.799 .212 .212

1170 17.74 932 16,537 8024946 2.187 .986 .014 24.36 679 16,537 5821595 1.666 .952 .048

1171 23.06 531 12,247 3212568 -.479 .316 .316 34.02 360 12,247 2155172 -.735 .231 .231

1172 21.54 899 19,365 8975691 1.618 .947 .053 29.57 655 19,365 6510948 1.181 .881 .119

1173 33.31 714 23,783 8500988 .057 .523 .477 48.94 486 23,783 5885031 .699 .758 .242

1174 36.55 139 5,080 370013 .981 .837 .163 54.04 94 5,080 255451 1.174 .880 .120

1175 33.57 808 27,125 11099654 .634 .737 .263 50.23 540 27,125 7517668 1.066 .857 .143

1176 32.70 20 654 5912 -.744 .229 .229 46.71 14 654 3801 -1.100 .136 .136

1177 27.33 52 1,421 36914 -.011 .496 .496 36.44 39 1,421 29814 .822 .794 .206

1178 28.51 626 17,848 5669091 .641 .739 .261 42.70 418 17,848 3747084 .160 .564 .436

1179 38.20 459 17,533 4111872 .812 .792 .208 55.66 315 17,533 2798061 .408 .658 .342

1180 44.08 38 1,675 32906 .363 .642 .358 62.04 27 1,675 24029 .564 .714 .286

1181 120.50 10 1,205 6623 .544 .707 .293 200.83 6 1,205 3056 -.656 .256 .256

1182 14.87 651 9,681 3272001 1.695 .955 .045 20.30 477 9,681 2431088 2.002 .977 .023

1183 18.69 1,049 19,606 10855035 3.119 .999 .001 26.07 752 19,606 7907333 3.450 1.000 0

1184 167.35 48 8,033 175792 -1.058 .145 .145 334.71 24 8,033 79504 -1.487 .069 .069

1185 29.81 287 8,556 1222825 -.119 .453 .453 41.33 207 8,556 888757 .090 .536 .464

1186 17.99 335 6,027 1038258 .902 .817 .183 25.98 232 6,027 707935 .332 .630 .370

1187 14.55 789 11,476 4617499 .970 .834 .166 20.03 573 11,476 3349278 .774 .781 .219

1188 125.08 80 10,006 420734 .793 .786 .214 185.30 54 10,006 284238 .663 .746 .254

1189 34.46 556 19,158 5560050 1.795 .964 .036 51.50 372 19,158 3836609 2.561 .995 .005

1190 18.96 1,006 19,072 9749032 .892 .814 .186 27.44 695 19,072 6700593 .504 .693 .307

1191 65.82 11 724 3152 -1.197 .116 .116 120.67 6 724 1244 -1.813 .035 .035

1192 34.31 189 6,484 640714 1.087 .861 .139 58.41 111 6,484 353947 -.300 .382 .382

Table 5. Summary of interoccurrence intervals for daily precipitation thresholds of 0.75 and 1.0 inch—Continued

Seq.

no.

Daily precipitation threshold of 0.75 inch and greater Daily precipitation threshold of 1.0 inch and greater

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue
Table 5 139

1193 21.82 350 7,637 1328263 -0.199 .421 .421 33.79 226 7,637 854958 -0.242 .404 .404

1194 20.57 405 8,332 1697858 .220 .587 .413 28.83 289 8,332 1265362 1.501 .933 .067

1195 16.47 135 2,224 154925 .644 .740 .260 23.66 94 2,224 100194 -.696 .243 .243

1196 18.05 356 6,424 1154358 .311 .622 .378 26.55 242 6,424 777781 .017 .507 .493

1197 23.99 826 19,815 8529806 2.106 .982 .018 35.07 565 19,815 5750694 1.125 .870 .130

1198 37.35 243 9,076 1207247 2.559 .995 .005 55.68 163 9,076 821213 2.437 .993 .007

1199 60.00 6 360 1256 .691 .755 .245 72.00 5 360 904 .017 .507 .493

1200 34.18 421 14,391 3082424 .623 .733 .267 48.13 299 14,391 2218783 .937 .826 .174

1201 58.09 33 1,917 32761 .356 .639 .361 91.29 21 1,917 22856 1.076 .859 .141

1202 51.19 379 19,400 3869230 1.770 .962 .038 84.72 229 19,400 2326329 1.239 .892 .108

1203 39.43 398 15,694 2822862 -3.322 0 0 64.85 242 15,694 1687109 -3.006 .001 .001

1204 44.61 347 15,481 2912047 2.716 .997 .003 73.72 210 15,481 1868892 3.758 1.000 0

1205 17.02 381 6,485 1271837 .997 .841 .159 23.16 280 6,485 955354 1.515 .935 .065

1206 19.76 536 10,592 2792980 -.645 .259 .259 27.16 390 10,592 2012775 -.872 .192 .192

1207 19.08 320 6,104 948645 -.888 .187 .187 27.13 225 6,104 685419 -.049 .481 .481

1208 53.15 367 19,506 3681876 .950 .829 .171 84.08 232 19,506 2358161 1.113 .867 .133

1209 -- -- -- -- -- -- -- -- -- -- -- -- -- --

1210 25.23 147 3,709 256766 -1.221 .111 .111 35.66 104 3,709 178994 -1.271 .102 .102

1211 37.72 744 28,061 10571473 .601 .726 .274 54.91 511 28,061 7360273 1.041 .851 .149

1212 40.82 236 9,634 1166503 .695 .756 .244 56.01 172 9,634 859471 .849 .802 .198

1213 34.87 157 5,474 423763 -.300 .382 .382 48.88 112 5,474 330420 1.428 .923 .077

1214 32.91 22 724 7574 -.398 .345 .345 45.25 16 724 5790 -.002 .499 .499

1215 88.01 97 8,537 342437 -2.950 .002 .002 131.34 65 8,537 240703 -1.850 .032 .032

1216 76.93 328 25,234 3935717 -1.536 .062 .062 135.67 186 25,234 2097835 -2.506 .006 .006

1217 23.45 560 13,130 3738903 .697 .757 .243 32.10 409 13,130 2749923 .846 .801 .199

1218 20.69 158 3,269 256952 -.110 .456 .456 26.80 122 3,269 197563 -.177 .430 .430

1219 22.99 854 19,632 8818311 2.629 .996 .004 33.05 594 19,632 6292602 3.344 1.000 0

1220 108.36 193 20,914 2048269 .359 .640 .360 193.65 108 20,914 1185527 .895 .815 .185

1221 36.73 160 5,877 474513 .203 .580 .420 54.93 107 5,877 307851 -.374 .354 .354

1222 114.50 2 229 39 -2.032 .021 .021 -- -- -- -- -- -- --

1223 25.59 214 5,476 603556 .762 .777 .223 34.88 157 5,476 436595 .340 .633 .367

1224 26.03 76 1,978 73212 -.392 .348 .348 36.63 54 1,978 57346 .939 .826 .174

1225 24.99 106 2,649 143314 .371 .645 .356 33.11 80 2,649 105352 -.089 .465 .465

1226 53.03 413 21,901 4241707 -2.186 .014 .014 83.27 263 21,901 2671935 -2.029 .021 .021

1227 28.52 219 6,246 685982 .077 .531 .469 38.80 161 6,246 510304 .328 .629 .371

1228 31.50 796 25,070 9987253 .046 .518 .482 45.42 552 25,070 6982856 .374 .646 .354

1229 23.32 633 14,762 4746346 .692 .755 .245 32.09 460 14,762 3487761 1.012 .844 .156

1230 24.09 596 14,360 4310172 .305 .620 .380 33.55 428 14,360 3148045 .875 .809 .191

1231 21.64 36 779 15102 .800 .788 .212 29.96 26 779 10832 .615 .731 .269

1232 23.21 42 975 23265 1.530 .937 .063 29.55 33 975 18736 1.638 .949 .051

1233 29.74 179 5,323 496072 .957 .831 .169 42.93 124 5,323 364121 1.993 .977 .023

1234 31.18 358 11,164 2132733 2.204 .986 .014 46.52 240 11,164 1369336 .594 .724 .276

1235 28.55 145 4,140 315745 1.084 .861 .139 40.19 103 4,140 221730 .702 .759 .241

1236 26.07 85 2,216 86253 -1.344 .089 .089 36.33 61 2,216 62828 -.953 .170 .170

1237 21.87 601 13,142 4050772 1.092 .863 .137 30.71 428 13,142 2796161 -.207 .418 .418

1238 25.84 986 25,474 12791528 1.008 .843 .157 38.54 661 25,474 8433908 .078 .531 .469

1239 23.40 643 15,049 4873781 .323 .626 .374 34.60 435 15,049 3277055 .043 .517 .483

1240 50.73 37 1,877 29119 -1.701 .045 .045 93.85 20 1,877 15563 -1.324 .093 .093

1241 20.17 896 18,072 8253585 1.008 .843 .157 28.42 636 18,072 5914330 1.273 .898 .102

1242 26.68 28 747 11895 1.259 .896 .104 35.57 21 747 8738 .905 .817 .183

1243 15.92 1,106 17,604 10023323 1.706 .956 .044 22.12 796 17,604 7176527 1.187 .882 .118

1244 20.29 944 19,152 9214290 1.028 .848 .152 28.25 678 19,152 6561616 .480 .684 .316

Table 5. Summary of interoccurrence intervals for daily precipitation thresholds of 0.75 and 1.0 inch—Continued

Seq.

no.

Daily precipitation threshold of 0.75 inch and greater Daily precipitation threshold of 1.0 inch and greater

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue
140 Atlas of Interoccurrence Intervals for Selected Thresholds of Daily Precipitation in Texas 

1245 40.42 469 18,958 4652097 1.742 .959 .041 61.95 306 18,958 3086632 1.944 .974 .026

1246 64.22 36 2,312 39364 -.562 .287 .287 77.07 30 2,312 32466 -.606 .272 .272

1247 38.34 396 15,182 3055202 .564 .713 .287 60.01 253 15,182 1966440 .659 .745 .255

1248 8.71 7 61 206 -.161 .436 .436 10.17 6 61 193 .232 .592 .408

1249 27.21 453 12,327 2928168 1.797 .964 .036 42.51 290 12,327 1895133 1.778 .962 .038

1250 22.19 1,661 36,857 31248556 1.473 .930 .070 32.25 1,143 36,857 21332682 .748 .773 .227

1251 44.32 25 1,108 11675 -1.360 .087 .087 61.56 18 1,108 7864 -1.553 .060 .060

1252 25.26 1,404 35,470 25532251 1.648 .950 .050 37.94 935 35,470 17254163 2.146 .984 .016

1253 20.11 222 4,465 503163 .393 .653 .347 26.42 169 4,465 360798 -.984 .163 .163

1254 18.24 25 456 5796 .146 .558 .442 19.00 24 456 5757 .442 .671 .329

1255 24.87 540 13,428 3506521 -1.322 .093 .093 34.08 394 13,428 2544266 -1.313 .095 .095

1256 37.29 549 20,473 5709544 .648 .741 .259 57.83 354 20,473 3904076 2.521 .994 .006

1257 42.45 460 19,529 4758703 2.209 .986 .014 59.36 329 19,529 3434156 2.168 .985 .015

1258 21.12 172 3,633 323041 .771 .780 .220 30.28 120 3,633 226682 .757 .776 .224

1259 229.00 1 229 228 1.717 .957 .043 229.00 1 229 228 1.717 .957 .043

1260 20.36 1,070 21,784 12170025 2.507 .994 .006 28.82 756 21,784 8762476 3.054 .999 .001

1261 38.04 215 8,179 879861 .018 .507 .493 56.02 146 8,179 607088 .351 .637 .363

1262 27.48 42 1,154 23923 -.144 .443 .443 44.39 26 1,154 13707 -.762 .223 .223

1263 12.29 42 516 10910 .077 .531 .469 15.64 33 516 8424 -.105 .458 .458

1264 40.74 38 1,548 30151 .268 .606 .394 81.47 19 1,548 14286 -.216 .415 .415

1265 17.36 199 3,454 372397 2.042 .979 .021 23.66 146 3,454 272643 1.702 .956 .044

1266 24.35 782 19,044 7581193 .878 .810 .190 36.14 527 19,044 5072154 .428 .666 .334

1267 30.23 446 13,484 3014479 .092 .537 .463 45.25 298 13,484 1981873 -.405 .343 .343

1268 31.72 541 17,161 4566602 -.655 .256 .256 43.89 391 17,161 3269748 -.870 .192 .192

1269 -- -- -- -- -- -- -- -- -- -- -- -- -- --

1270 34.17 64 2,187 67773 -.438 .331 .331 49.71 44 2,187 48154 .010 .504 .496

1271 30.47 1,151 35,073 19872285 -.909 .182 .182 45.14 777 35,073 13161745 -1.645 .050 .050

1272 33.82 118 3,991 232558 -.233 .408 .408 49.27 81 3,991 169824 .790 .785 .215

1273 29.41 324 9,529 1563768 .405 .657 .343 42.35 225 9,529 1074790 .067 .527 .473

1274 15.90 387 6,153 1227049 1.043 .851 .149 21.98 280 6,153 897155 1.202 .885 .115

1275 14.84 243 3,606 456806 1.151 .875 .125 19.92 181 3,606 347439 1.506 .934 .066

1276 20.55 269 5,527 756832 .514 .696 .304 27.50 201 5,527 545502 -.440 .330 .330

1277 15.42 166 2,560 214498 .212 .584 .416 17.53 146 2,560 199537 1.417 .922 .078

1278 19.22 1,508 28,977 21626925 -.683 .247 .247 27.81 1,042 28,977 15279515 .676 .750 .250

1279 62.54 24 1,501 13056 -2.335 .010 .010 75.05 20 1,501 9721 -2.729 .003 .003

1280 38.98 138 5,379 427031 3.063 .999 .001 56.62 95 5,379 281374 1.709 .956 .044

1281 21.54 288 6,203 884892 -.274 .392 .392 30.86 201 6,203 623404 0 .500 .500

1282 49.00 5 245 891 1.761 .961 .039 122.50 2 245 409 1.640 .949 .051

1283 30.42 172 5,233 492673 2.152 .984 .016 43.98 119 5,233 373399 3.765 1.000 0

1284 16.53 591 9,769 2983915 1.417 .922 .078 21.86 447 9,769 2282486 1.662 .952 .048

1285 88.10 239 21,056 2446490 -.742 .229 .229 135.85 155 21,056 1569786 -.820 .206 .206

1286 17.68 1,035 18,295 9529412 .363 .642 .358 24.33 752 18,295 6803569 -.520 .301 .301

1287 46.72 128 5,980 364138 -.951 .171 .171 62.29 96 5,980 273455 -.803 .211 .211

1288 35.23 342 12,048 1936994 -1.916 .028 .028 52.84 228 12,048 1363878 -.183 .427 .427

1289 35.47 391 13,868 2744909 .426 .665 .335 50.80 273 13,868 1975475 1.247 .894 .106

1290 39.72 36 1,430 27977 .903 .817 .183 59.58 24 1,430 19900 1.355 .912 .088

1291 29.66 41 1,216 25170 .108 .543 .457 43.43 28 1,216 16778 -.132 .447 .447

1292 18.80 1,046 19,665 10597381 1.703 .956 .044 27.01 728 19,665 7292171 .876 .809 .191

1293 27.71 615 17,041 5256567 .135 .554 .446 39.82 428 17,041 3662560 .155 .562 .438

1294 32.01 158 5,058 378815 -1.132 .129 .129 45.16 112 5,058 265261 -1.164 .122 .122

1295 19.33 33 638 13818 3.111 .999 .001 27.74 23 638 9895 2.896 .998 .002

1296 14.05 303 4,257 648959 .188 .575 .425 19.18 222 4,257 478106 .305 .620 .380

Table 5. Summary of interoccurrence intervals for daily precipitation thresholds of 0.75 and 1.0 inch—Continued

Seq.

no.

Daily precipitation threshold of 0.75 inch and greater Daily precipitation threshold of 1.0 inch and greater

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue
Table 5 141

1297 32.25 84 2,709 103760 -1.398 .081 .081 41.68 65 2,709 81499 -1.038 .150 .150

1298 23.57 63 1,485 43281 -1.028 .152 .152 33.75 44 1,485 30691 -.696 .243 .243

1299 15.82 613 9,696 3090327 1.710 .956 .044 23.03 421 9,696 2160608 2.083 .981 .019

1300 26.00 7 182 897 1.870 .969 .031 60.67 3 182 477 2.242 .988 .012

1301 23.18 1,199 27,787 17035794 1.359 .913 .087 31.72 876 27,787 12594492 1.785 .963 .037

1302 26.07 717 18,695 6938528 1.636 .949 .051 37.09 504 18,695 4800181 .735 .769 .231

1303 17.12 17 291 2289 -.533 .297 .297 20.79 14 291 1806 -.735 .231 .231

1304 24.11 151 3,640 278253 .266 .605 .395 35.00 104 3,640 198098 .823 .795 .205

1305 165.37 137 22,655 1624674 .951 .829 .171 359.60 63 22,655 776214 1.206 .886 .114

1306 46.21 324 14,972 2416316 -.118 .453 .453 66.54 225 14,972 1668647 -.242 .404 .404

Table 5. Summary of interoccurrence intervals for daily precipitation thresholds of 0.75 and 1.0 inch—Continued

Seq.

no.

Daily precipitation threshold of 0.75 inch and greater Daily precipitation threshold of 1.0 inch and greater

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue
142 Atlas of Interoccurrence Intervals for Selected Thresholds of Daily Precipitation in Texas 

Table 6. Summary of interoccurrence intervals for daily precipitation thresholds of 1.5 and 2.0 inches—Continued

Seq.

no.

Daily precipitation threshold of 1.5 inches and greater Daily precipitation threshold of 2.0 inches and greater

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue

1 216.82 90 19,514 792213 -1.608 .054 .054 464.62 42 19,514 424095 0.392 .652 .348

2 120.00 2 240 197 -.439 .330 .330 -- -- -- -- -- -- --

3 135.07 146 19,720 1429563 -.145 .442 .442 318.07 62 19,720 585942 -.566 .286 .286

4 115.29 73 8,416 266028 -1.983 .024 .024 179.06 47 8,416 183840 -.837 .201 .201

5 191.85 99 18,993 1010585 1.291 .902 .098 345.33 55 18,993 574560 1.285 .901 .099

6 135.46 26 3,522 44689 -.212 .416 .416 220.13 16 3,522 32131 .973 .835 .165

7 81.82 101 8,264 375112 -1.761 .039 .039 165.28 50 8,264 165644 -2.428 .008 .008

8 208.29 7 1,458 5869 .688 .754 .246 729.00 2 1,458 1566 .181 .572 .428

9 144.65 20 2,893 26812 -.567 .285 .285 289.30 10 2,893 13466 -.378 .353 .353

10 214.00 1 214 92 -.243 .404 .404 214.00 1 214 92 -.243 .404 .404

11 91.34 67 6,120 197715 -.505 .307 .307 136.00 45 6,120 135097 -.220 .413 .413

12 99.39 358 35,581 6726653 1.840 .967 .033 193.38 184 35,581 3349281 .544 .707 .293

13 84.77 177 15,005 1365025 .644 .740 .260 180.78 83 15,005 637951 .386 .650 .350

14 97.61 307 29,966 4626092 .174 .569 .431 161.98 185 29,966 2824996 .452 .674 .326

15 142.42 12 1,709 11744 .872 .808 .192 189.89 9 1,709 9399 1.154 .876 .124

16 -- -- -- -- -- -- -- -- -- -- -- -- -- --

17 -- -- -- -- -- -- -- -- -- -- -- -- -- --

18 305.99 90 27,539 1286438 .626 .734 .266 764.97 36 27,539 576286 1.689 .954 .046

19 52.43 367 19,240 3819007 2.711 .997 .003 95.25 202 19,240 2033011 1.137 .872 .128

20 57.76 106 6,122 309431 -.826 .204 .204 103.76 59 6,122 179499 -.081 .468 .468

21 71.34 74 5,279 179532 -1.205 .114 .114 128.76 41 5,279 98177 -1.029 .152 .152

22 46.18 748 34,541 12991495 .268 .606 .394 75.75 456 34,541 7716839 -.744 .228 .228

23 59.35 20 1,187 11844 -.017 .493 .493 148.38 8 1,187 4958 .217 .586 .414

24 194.98 101 19,693 884153 -1.931 .027 .027 468.88 42 19,693 387482 -.708 .240 .240

25 143.29 96 13,756 570877 -2.298 .011 .011 264.54 52 13,756 300194 -2.007 .022 .022

26 39.62 785 31,099 12296383 .358 .640 .360 66.17 470 31,099 7474794 .856 .804 .196

27 49.61 419 20,787 4244664 -.897 .185 .185 88.08 236 20,787 2301509 -1.642 .050 .050

28 86.49 139 12,022 859757 .592 .723 .277 166.97 72 12,022 446181 .455 .675 .325

29 233.59 68 15,884 492487 -1.258 .104 .104 512.39 31 15,884 182711 -2.487 .006 .006

30 39.10 809 31,631 13831485 3.992 1.000 0 65.49 483 31,631 8470977 4.146 1.000 0

31 60.84 298 18,129 2903316 2.237 .987 .013 107.91 168 18,129 1643022 1.772 .962 .038

32 104.05 160 16,648 1293183 -.636 .262 .262 198.19 84 16,648 677086 -.502 .308 .308

33 87.15 266 23,183 3217226 1.227 .890 .110 183.99 126 23,183 1511678 .681 .752 .248

34 78.74 46 3,622 77235 -.856 .196 .196 164.64 22 3,622 42501 .542 .706 .294

35 68.61 150 10,292 840037 1.873 .969 .031 113.10 91 10,292 505010 1.296 .902 .098

36 51.07 217 11,081 1146377 -1.187 .118 .118 81.48 136 11,081 755338 .049 .520 .480

37 65.34 167 10,911 944793 .829 .796 .204 106.97 102 10,911 584847 .892 .814 .186

38 91.84 244 22,410 2762838 .285 .612 .388 176.46 127 22,410 1416904 -.084 .466 .466

39 61.43 318 19,535 3245017 1.382 .916 .084 135.66 144 19,535 1582865 2.606 .995 .005

40 81.09 128 10,379 697898 .993 .839 .161 152.63 68 10,379 357175 .174 .569 .431

41 54.36 456 24,787 5752843 .664 .747 .254 105.93 234 24,787 2996780 .884 .811 .189

42 67.64 11 744 3770 -.452 .326 .326 93.00 8 744 2434 -.892 .186 .186

43 127.82 251 32,082 3902049 -.847 .199 .199 286.45 112 32,082 1724842 -.732 .232 .232

44 52.98 371 19,656 3807606 1.477 .930 .070 102.38 192 19,656 1972998 1.094 .863 .137

45 47.37 400 18,947 4075934 2.619 .996 .004 83.84 226 18,947 2282998 1.727 .958 .042

46 76.04 340 25,853 4437882 .312 .622 .378 146.89 176 25,853 2187903 -.880 .189 .189

47 79.54 80 6,363 291554 2.254 .988 .012 159.08 40 6,363 147952 1.781 .963 .037

48 72.41 78 5,648 251106 2.141 .984 .016 131.35 43 5,648 134130 1.188 .882 .118

Table 6 Table 6. Summary of interoccurrence intervals for daily precipitation thresholds of 1.5 and 2.0 inches

[--, not available, no events that equal or exceed the threshold were observed]
Table 6 143

49 43.14 7 302 1187 .564 .713 .287 100.67 3 302 770 2.099 .982 .018

50 101.67 9 915 4872 .952 .829 .171 130.71 7 915 3358 .223 .588 .412

51 69.03 264 18,223 2453903 .567 .715 .285 127.43 143 18,223 1315188 .195 .577 .423

52 61.26 214 13,109 1359432 -.781 .218 .218 116.01 113 13,109 730693 -.248 .402 .402

53 38.25 8 306 1448 .897 .815 .185 61.20 5 306 1166 2.030 .979 .021

54 29.00 3 87 96 -.793 .214 .214 43.50 2 87 61 -.732 .232 .232

55 87.30 113 9,865 582592 .833 .798 .202 170.09 58 9,865 308843 1.049 .853 .147

56 149.06 16 2,385 14434 -1.687 .046 .046 298.13 8 2,385 5168 -2.245 .012 .012

57 264.58 74 19,579 831124 2.195 .986 .014 652.63 30 19,579 304705 .356 .639 .361

58 101.33 6 608 978 -1.968 .025 .025 152.00 4 608 483 -2.088 .018 .018

59 130.78 277 36,226 5043182 .149 .559 .441 283.02 128 36,226 2445721 1.076 .859 .141

60 -- -- -- -- -- -- -- -- -- -- -- -- -- --

61 306.21 91 27,865 1283805 .208 .582 .418 714.49 39 27,865 605650 1.240 .892 .108

62 -- -- -- -- -- -- -- -- -- -- -- -- -- --

63 226.56 9 2,039 9024 -.086 .466 .466 339.83 6 2,039 4789 -.921 .179 .179

64 -- -- -- -- -- -- -- -- -- -- -- -- -- --

65 73.49 101 7,422 391097 .756 .775 .225 134.95 55 7,422 223773 1.238 .892 .108

66 63.08 37 2,334 40624 -.623 .267 .267 106.09 22 2,334 21496 -1.322 .093 .093

67 66.04 202 13,340 1359022 .213 .585 .415 123.52 108 13,340 754510 .853 .803 .197

68 201.42 26 5,237 69366 .167 .566 .434 654.63 8 5,237 21574 .146 .558 .442

69 351.21 14 4,917 35508 .205 .581 .419 1639.00 3 4,917 8379 .408 .658 .342

70 69.07 15 1,036 11295 3.043 .999 .001 148.00 7 1,036 5263 2.069 .981 .019

71 95.25 8 762 4072 1.646 .950 .050 381.00 2 762 1012 .804 .789 .211

72 111.95 39 4,366 89271 .525 .700 .300 242.56 18 4,366 34656 -.867 .193 .193

73 84.48 148 12,503 951567 .600 .726 .274 148.85 84 12,503 568960 1.325 .907 .093

74 63.58 19 1,208 13860 1.568 .942 .058 80.53 15 1,208 10262 .890 .813 .187

75 46.41 505 23,435 6447518 3.487 1.000 0 78.64 298 23,435 3907084 3.556 1.000 0

76 128.22 9 1,154 5488 .295 .616 .384 230.80 5 1,154 3600 .960 .831 .169

77 38.63 410 15,838 3359253 1.215 .888 .112 68.56 231 15,838 1936535 1.543 .939 .061

78 90.50 8 724 2383 -.868 .193 .193 120.67 6 724 1352 -1.602 .055 .055

79 83.29 7 583 2755 1.605 .946 .054 116.60 5 583 2023 1.503 .934 .066

80 39.34 905 35,599 16377478 .870 .808 .192 70.91 502 35,599 9010886 .328 .629 .371

81 40.48 349 14,126 2638406 2.276 .989 .011 70.99 199 14,126 1514357 1.892 .971 .029

82 45.58 278 12,671 1814451 .872 .808 .192 79.69 159 12,671 1030440 .501 .692 .308

83 79.58 448 35,650 8424492 2.015 .978 .022 143.75 248 35,650 4553909 .823 .795 .205

84 53.51 146 7,812 543873 -.969 .166 .166 95.27 82 7,812 300943 -.948 .172 .172

85 55.17 30 1,655 27894 1.173 .880 .120 91.94 18 1,655 14930 .017 .507 .493

86 76.47 189 14,452 1411273 .794 .786 .214 145.98 99 14,452 775461 1.448 .926 .074

87 101.08 12 1,213 6996 -.233 .408 .408 134.78 9 1,213 5623 .157 .562 .438

88 82.92 155 12,853 1044511 1.048 .853 .147 158.68 81 12,853 548622 .841 .800 .200

89 81.49 234 19,069 2384582 1.823 .966 .034 168.75 113 19,069 1149124 1.226 .890 .110

90 103.10 62 6,392 214051 1.094 .863 .137 188.00 34 6,392 112756 .380 .648 .352

91 130.64 95 12,411 573741 -.452 .326 .326 253.29 49 12,411 255429 -1.940 .026 .026

92 75.06 165 12,385 1026611 .106 .542 .458 137.61 90 12,385 540775 -.488 .313 .313

93 34.26 62 2,124 67578 0.359 .640 .360 60.69 35 2,124 35433 -0.479 .316 .316

94 609.00 4 2,436 3981 -.634 .263 .263 2436.00 1 2,436 478 -1.052 .146 .146

95 94.00 11 1,034 4879 -.816 .207 .207 258.50 4 1,034 1316 -1.260 .104 .104

96 155.07 89 13,801 571154 -1.144 .126 .126 373.00 37 13,801 256011 .029 .511 .489

Table 6. Summary of interoccurrence intervals for daily precipitation thresholds of 1.5 and 2.0 inches—Continued

Seq.

no.

Daily precipitation threshold of 1.5 inches and greater Daily precipitation threshold of 2.0 inches and greater

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue
144 Atlas of Interoccurrence Intervals for Selected Thresholds of Daily Precipitation in Texas 

97 376.33 3 1,129 1299 -.699 .242 .242 564.50 2 1,129 952 -.384 .350 .350

98 149.95 127 19,044 1294319 1.372 .915 .085 317.40 60 19,044 625279 1.267 .897 .103

99 114.00 1 114 98 1.246 .894 .106 114.00 1 114 98 1.246 .894 .106

100 110.78 258 28,580 4065934 2.861 .998 .002 194.42 147 28,580 2287340 1.867 .969 .031

101 92.11 100 9,211 437782 -.856 .196 .196 187.98 49 9,211 228392 .146 .558 .442

102 49.44 16 791 7242 1.001 .841 .159 79.10 10 791 4554 .830 .797 .203

103 79.17 473 37,448 9364361 2.160 .985 .015 158.68 236 37,448 4872472 2.731 .997 .003

104 96.55 65 6,276 232255 1.937 .974 .026 224.14 28 6,276 103605 1.642 .950 .050

105 89.10 115 10,246 575078 -.444 .329 .329 150.68 68 10,246 354177 .238 .594 .406

106 274.00 13 3,562 14491 -2.336 .010 .010 712.40 5 3,562 5975 -1.274 .101 .101

107 63.99 117 7,487 460420 .960 .831 .169 133.70 56 7,487 195378 -.882 .189 .189

108 68.90 542 37,342 10176170 .225 .589 .411 124.47 300 37,342 5546614 -.293 .385 .385

109 36.21 398 14,412 2957601 1.080 .860 .140 67.66 213 14,412 1534407 -.008 .497 .497

110 53.24 652 34,710 12065743 2.933 .998 .002 102.69 338 34710 6155040 1.569 .942 .058

111 73.77 17 1,254 9801 -.575 .283 .283 125.40 10 1,254 4530 -1.520 .064 .064

112 192.90 119 22,955 1346782 -.263 .396 .396 425.09 54 22,955 625039 .108 .543 .457

113 218.64 11 2,405 10070 -1.371 .085 .085 267.22 9 2,405 7511 -1.590 .056 .056

114 154.31 13 2,006 13873 .399 .655 .345 334.33 6 2,006 7881 1.313 .905 .095

115 860.10 21 18,062 208999 .810 .791 .209 3612.40 5 18,062 35245 -.850 .198 .198

116 207.32 28 5,805 86243 .561 .712 .288 580.50 10 5,805 25446 -.675 .250 .250

117 198.08 97 19,214 941644 .179 .571 .429 457.48 42 19,214 402568 -.026 .490 .490

118 144.43 7 1,011 3811 .353 .638 .362 505.50 2 1,011 1133 .296 .616 .384

119 83.85 329 27,586 4662511 .863 .806 .194 160.38 172 27,586 2403847 .301 .618 .382

120 44.70 429 19,175 4214370 .884 .812 .188 84.47 227 19,175 2219862 .522 .699 .301

121 71.16 258 18,359 2766617 4.679 1.000 0 130.21 141 18,359 1530989 3.761 1.000 0

122 157.15 55 8,643 248741 .598 .725 .275 308.68 28 8,643 129569 .649 .742 .258

123 105.21 328 34,510 5719266 .331 .630 .371 176.97 195 34,510 3475913 .799 .788 .212

124 87.79 86 7,550 321709 -.146 .442 .442 125.83 60 7,550 220208 -.373 .355 .355

125 121.06 196 23,727 2460249 1.408 .920 .080 244.61 97 23,727 1244998 1.397 .919 .081

126 57.44 63 3,619 105090 -1.074 .141 .141 109.67 33 3,619 65655 .990 .839 .161

127 210.71 92 19,385 880485 -.209 .417 .417 523.92 37 19,385 347693 -.321 .374 .374

128 44.07 247 10,885 1316941 -.554 .290 .290 77.20 141 10,885 782592 .407 .658 .342

129 89.25 220 19,634 2242216 .981 .837 .163 173.75 113 19,634 1097961 -.189 .425 .425

130 104.56 252 26,350 3402515 .683 .752 .248 215.98 122 26,350 1652488 .537 .704 .296

131 95.13 8 761 2369 -1.086 .139 .139 152.20 5 761 1579 -.659 .255 .255

132 66.23 212 14,041 1526447 .646 .741 .259 126.50 111 14,041 790702 .268 .606 .394

133 56.02 648 36,302 11829598 .254 .600 .400 106.46 341 36,302 6441003 1.300 .903 .097

134 109.27 11 1,202 3323 -2.857 .002 .002 300.50 4 1,202 1103 -1.875 .030 .030

135 121.60 10 1,216 6372 .263 .604 .396 304.00 4 1,216 2302 -.185 .426 .426

136 83.16 373 31,019 6051385 1.540 .938 .062 159.07 195 31,019 3076307 .416 .661 .339

137 75.15 47 3,532 90765 1.111 .867 .133 235.47 15 3,532 27701 .307 .620 .380

138 84.03 91 7,647 412793 3.080 .999 .001 129.61 59 7,647 268256 2.517 .994 .006

139 -- -- -- -- -- -- -- -- -- -- -- -- -- --

140 64.50 20 1,290 13472 .344 .634 .366 143.33 9 1,290 6197 .351 .637 .363

141 47.85 223 10,670 1141068 -1.057 .145 .145 95.27 112 10,670 552467 -1.382 .084 .084

142 39.74 202 8,028 861541 1.540 .938 .062 75.03 107 8,028 462483 1.376 .916 .084

143 43.72 411 17,968 3681383 -.105 .458 .458 84.36 213 17,968 1840908 -.960 .169 .169

144 167.90 82 13,768 531733 -.910 .181 .181 312.91 44 13,768 286814 -.610 .271 .271

Table 6. Summary of interoccurrence intervals for daily precipitation thresholds of 1.5 and 2.0 inches—Continued

Seq.

no.

Daily precipitation threshold of 1.5 inches and greater Daily precipitation threshold of 2.0 inches and greater

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue
Table 6 145

145 172.97 101 17,470 884271 .040 .516 .484 356.53 49 17,470 446322 .519 .698 .302

146 101.92 278 28,335 4033791 .698 .757 .243 168.66 168 28,335 2566251 1.755 .960 .040

147 93.42 208 19,432 2306508 3.530 1.000 0 168.97 115 19,432 1244734 2.118 .983 .017

148 253.40 5 1,267 3291 .151 .560 .440 316.75 4 1,267 2764 .314 .623 .377

149 35.67 6 214 832 1.256 .895 .105 71.33 3 214 498 1.654 .951 .049

150 96.33 12 1,156 6196 -.640 .261 .261 192.67 6 1,156 3459 -.011 .496 .496

151 104.73 67 7,017 221196 -.837 .201 .201 212.64 33 7,017 117640 .160 .564 .436

152 416.11 19 7,906 74062 -.105 .458 .458 878.44 9 7,906 30212 -.784 .217 .217

153 53.45 271 14,486 2115933 2.224 .987 .013 94.07 154 14,486 1226952 2.149 .984 .016

154 209.51 51 10,685 230446 -1.908 .028 .028 508.81 21 10,685 75291 -2.611 .005 .005

155 69.78 316 22,051 3611690 1.128 .870 .130 118.55 186 22,051 2194560 1.657 .951 .049

156 358.76 41 14,709 266258 -1.298 .097 .097 668.59 22 14,709 140790 -1.055 .146 .146

157 -- -- -- -- -- -- -- -- -- -- -- -- -- --

158 107.21 19 2,037 16367 -1.164 .122 .122 226.33 9 2,037 9122 -.025 .490 .490

159 83.79 210 17,595 1860284 .174 .569 .431 162.92 108 17,595 937839 -.233 .408 .408

160 74.76 80 5,981 243381 .268 .606 .394 115.02 52 5,981 149917 -.449 .327 .327

161 82.72 163 13,484 1134662 .719 .764 .236 175.12 77 13,484 516833 -.067 .473 .473

162 79.19 124 9,819 655636 1.485 .931 .069 138.30 71 9,819 397825 2.062 .980 .020

163 85.42 403 34,426 7216573 1.402 .920 .080 162.39 212 34,426 3639893 -.064 .474 .474

164 86.33 6 518 1846 .797 .787 .213 172.67 3 518 1149 1.436 .925 .075

165 237.00 5 1,185 1939 -1.338 .090 .090 592.50 2 1,185 1388 .420 .663 .337

166 84.41 75 6,331 245640 .520 .698 .302 143.89 44 6,331 138682 -.050 .480 .480

167 172.43 7 1,207 3248 -1.059 .145 .145 603.50 2 1,207 1329 .248 .598 .402

168 60.24 234 14,097 1631326 -.290 .386 .386 120.49 117 14,097 824113 -.013 .495 .495

169 50.67 24 1,216 14081 -.297 .383 .383 93.54 13 1,216 8938 .817 .793 .207

170 132.26 46 6,084 151774 .994 .840 .160 304.20 20 6,084 70566 1.238 .892 .108

171 111.26 74 8,233 299377 -.257 .399 .399 216.66 38 8,233 148426 -.546 .293 .293

172 70.01 469 32,834 7681410 -.089 .465 .465 152.72 215 32,834 3561249 .227 .590 .410

173 94.19 21 1,978 22151 .528 .701 .299 164.83 12 1,978 14069 1.113 .867 .133

174 137.33 45 6,180 148485 .788 .785 .215 280.91 22 6,180 76544 1.024 .847 .153

175 57.88 24 1,389 19166 1.272 .898 .102 77.17 18 1,389 13519 .598 .725 .275

176 89.50 224 20,049 2381594 1.571 .942 .058 151.89 132 20,049 1433382 1.657 .951 .049

177 153.71 209 32,125 3233006 -.925 .177 .177 356.94 90 32,125 1409876 -.406 .342 .342

178 82.75 4 331 604 -.304 .381 .381 331.00 1 331 214 .508 .694 .306

179 512.11 38 19,460 441776 2.080 .981 .019 1946.00 10 19,460 130513 1.870 .969 .031

180 49.92 334 16,672 2861321 .877 .810 .190 91.10 183 16,672 1653730 1.970 .976 .024

181 196.10 144 28,238 2012657 -.209 .417 .417 397.72 71 28,238 989506 -.188 .425 .425

182 72.56 192 13,932 1336052 -.026 .490 .490 131.43 106 13,932 726243 -.294 .385 .385

183 66.69 29 1,934 34301 2.082 .981 .019 107.44 18 1,934 18201 .336 .631 .369

184 39.32 22 865 10283 .656 .744 .256 54.06 16 865 6280 -.641 .261 .261

185 314.86 7 2,204 7057 -.390 .348 .348 1102.00 2 2,204 2092 -.125 .450 .450

186 78.79 29 2,285 30996 -.602 .274 .274 142.81 16 2,285 19678 .530 .702 .298

187 -- -- -- -- -- -- -- -- -- -- -- -- -- --

188 99.46 149 14,820 1151185 .902 .816 .184 208.73 71 14,820 571104 1.248 .894 .106

189 119.53 221 26,415 2811276 -0.949 .171 .171 220.13 120 26,415 1406427 -2.137 .016 .016

190 62.41 303 18,911 2998027 1.400 .919 .081 116.02 163 18,911 1675817 1.931 .973 .027

191 107.72 119 12,819 816950 1.343 .910 .090 210.15 61 12,819 378287 -.439 .330 .330

192 46.02 395 18,176 3977036 3.714 1.000 0 83.38 218 18,176 2182206 2.595 .995 .005

Table 6. Summary of interoccurrence intervals for daily precipitation thresholds of 1.5 and 2.0 inches—Continued

Seq.

no.

Daily precipitation threshold of 1.5 inches and greater Daily precipitation threshold of 2.0 inches and greater

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue
146 Atlas of Interoccurrence Intervals for Selected Thresholds of Daily Precipitation in Texas 

193 196.19 62 12,164 460696 3.024 .999 .001 380.13 32 12,164 250645 2.820 .998 .002

194 88.07 73 6,429 227554 -.448 .327 .327 149.51 43 6,429 132158 -.498 .309 .309

195 729.69 13 9,486 43982 -1.790 .037 .037 3162.00 3 9,486 6958 -1.533 .063 .063

196 112.50 128 14,400 924235 .056 .522 .478 202.82 71 14,400 526458 .436 .668 .332

197 68.60 118 8,095 521134 1.715 .957 .043 132.71 61 8,095 278016 1.705 .956 .044

198 63.97 198 12,665 1334641 1.571 .942 .058 118.36 107 12,665 725172 1.259 .896 .104

199 41.81 546 22,827 6309060 .502 .692 .308 76.86 297 22,827 3423393 .296 .616 .384

200 93.52 151 14,121 1036128 -.599 .275 .275 172.21 82 14,121 540614 -1.039 .150 .150

201 55.54 413 22,939 4793769 .423 .664 .336 114.70 200 22,939 2381189 .932 .824 .176

202 97.20 5 486 1753 1.715 .957 .043 486.00 1 486 383 .998 .841 .159

203 82.88 170 14,090 1242751 .850 .802 .198 151.51 93 14,090 689784 .882 .811 .189

204 34.70 40 1,388 26644 -.440 .330 .330 51.41 27 1,388 16387 -1.129 .129 .129

205 192.00 2 384 333 -.325 .372 .372 384.00 1 384 170 -.199 .421 .421

206 243.75 12 2,925 16602 -.324 .373 .373 585.00 5 2,925 3731 -1.897 .029 .029

207 103.20 5 516 1054 -.709 .239 .239 516.00 1 516 446 1.262 .897 .104

208 161.55 51 8,239 263064 3.119 .999 .001 411.95 20 8,239 113836 2.956 .998 .002

209 69.51 220 15,291 1733555 .787 .784 .216 119.46 128 15,291 1023950 .908 .818 .182

210 116.00 37 4,292 93154 1.825 .966 .034 252.47 17 4,292 51140 2.869 .998 .002

211 113.33 18 2,040 16342 -.808 .210 .210 291.43 7 2,040 6231 -.583 .280 .280

212 94.93 151 14,334 1092873 .210 .583 .417 174.81 82 14,334 567247 -.546 .293 .293

213 58.76 54 3,173 91861 .920 .821 .179 105.77 30 3,173 49067 .293 .615 .385

214 105.64 11 1,162 5146 -1.119 .132 .132 581.00 2 1,162 1294 .278 .610 .390

215 133.50 6 801 2557 .272 .607 .393 200.25 4 801 1444 -.342 .366 .366

216 168.56 9 1,517 8134 .995 .840 .160 379.25 4 1,517 3399 .417 .662 .338

217 114.76 132 15,148 930418 -1.380 .084 .084 201.97 75 15,148 545722 -.590 .278 .278

218 179.58 103 18,497 1010286 1.065 .856 .144 330.30 56 18,497 575818 1.449 .926 .074

219 -- -- -- -- -- -- -- -- -- -- -- -- -- --

220 119.52 205 24,501 2325259 -1.838 .033 .033 237.87 103 24,501 1149374 -1.566 .059 .059

221 32.76 144 4,717 357775 1.111 .867 .133 56.83 83 4,717 193573 -.176 .430 .430

222 235.39 84 19,773 904969 1.424 .923 .077 599.18 33 19,773 376914 1.545 .939 .061

223 110.32 59 6,509 196801 .332 .630 .370 241.07 27 6,509 89039 .120 .548 .452

224 174.77 35 6,117 96752 -.986 .162 .162 339.83 18 6,117 52218 -.378 .353 .353

225 62.95 188 11,834 1126206 .295 .616 .384 103.81 114 11,834 622628 -1.423 .077 .077

226 135.96 246 33,447 4067333 -.308 .379 .379 274.16 122 33,447 1980127 -.564 .286 .286

227 52.17 23 1,200 15839 1.227 .890 .110 200.00 6 1,200 4026 .502 .692 .308

228 46.95 725 34,037 12570821 .879 .810 .190 95.34 357 34,037 6385917 1.672 .953 .047

229 82.07 111 9,110 571949 2.395 .992 .008 149.34 61 9,110 309699 1.550 .939 .061

230 140.38 228 32,007 3653463 .033 .513 .487 313.79 102 32,007 1642097 .104 .542 .458

231 68.94 480 33,090 8003597 .296 .616 .384 140.81 235 33,090 4042118 1.052 .854 .146

232 64.03 39 2,497 47875 -.181 .428 .428 104.04 24 2,497 31688 .488 .687 .313

233 40.00 432 17,281 3772048 .380 .648 .352 69.68 248 17,281 2234656 1.169 .879 .121

234 115.00 9 1,035 2358 -2.565 .005 .005 258.75 4 1,035 1215 -1.431 .076 .076

235 73.50 318 23,374 3457580 -2.152 .016 .016 130.58 179 23,374 1999733 -1.022 .154 .154

236 100.75 57 5,743 153958 -.776 .219 .219 147.26 39 5,743 104008 -.771 .220 .220

237 46.22 402 18,579 3790615 0.523 .699 .301 88.47 210 18,579 1983693 0.423 .664 .336

238 137.39 31 4,259 72102 .889 .813 .187 250.53 17 4,259 40618 .871 .808 .192

239 45.73 379 17,330 3450746 1.712 .957 .043 84.13 206 17,330 1894765 1.529 .937 .063

240 362.42 36 13,047 259898 1.109 .866 .134 931.93 14 13,047 105299 .991 .839 .161

Table 6. Summary of interoccurrence intervals for daily precipitation thresholds of 1.5 and 2.0 inches—Continued

Seq.

no.

Daily precipitation threshold of 1.5 inches and greater Daily precipitation threshold of 2.0 inches and greater

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue
Table 6 147

241 94.22 397 37,406 7654302 1.065 .857 .143 173.98 215 37,406 4164637 .906 .818 .182

242 59.38 295 17,517 2515618 -.785 .216 .216 114.49 153 17,517 1304529 -.568 .285 .285

243 63.05 328 20,679 3290229 -.935 .175 .175 109.41 189 20,679 1975008 .254 .600 .400

244 30.67 3 92 103 -.761 .223 .223 46.00 2 92 99 .186 .574 .426

245 139.59 189 26,383 2243801 -2.382 .009 .009 263.83 100 26,383 1128154 -2.508 .006 .006

246 51.36 390 20,030 4160527 2.230 .987 .013 95.84 209 20,030 2203750 1.323 .907 .093

247 93.07 328 30,526 5136876 .818 .793 .207 195.68 156 30,526 2644854 2.397 .992 .008

248 82.25 24 1,974 23549 -.050 .480 .480 131.60 15 1,974 15299 .224 .589 .411

249 47.11 64 3,015 102400 .850 .802 .198 79.34 38 3,015 64925 1.424 .923 .077

250 181.20 41 7,429 140610 -.851 .197 .197 323.00 23 7,429 76102 -.907 .182 .182

251 -- -- -- -- -- -- -- -- -- -- -- -- -- --

252 145.19 16 2,323 20037 .542 .706 .294 178.69 13 2,323 14378 -.298 .383 .383

253 107.69 13 1,400 10177 .739 .770 .230 233.33 6 1,400 5298 1.109 .866 .134

254 237.62 82 19,485 770239 -.562 .287 .287 573.09 34 19,485 323841 -.226 .411 .411

255 47.85 404 19,333 4213333 2.746 .997 .003 93.40 207 19,333 2228445 2.833 .998 .002

256 48.31 377 18,213 3735119 2.958 .998 .002 92.45 197 18,213 1935059 1.912 .972 .028

257 -- -- -- -- -- -- -- -- -- -- -- -- -- --

258 190.83 102 19,465 1142955 2.647 .996 .004 405.52 48 19,465 582661 2.967 .999 .002

259 86.90 52 4,519 101349 -1.716 .043 .043 205.41 22 4,519 40331 -1.533 .063 .063

260 69.60 317 22,062 3474463 -.197 .422 .422 135.35 163 22,062 1794264 -.047 .481 .481

261 112.39 13 1,461 10084 .386 .650 .350 146.10 10 1,461 7138 -.125 .450 .450

262 65.17 103 6,712 342087 -.182 .428 .428 156.09 43 6,712 141413 -.228 .410 .410

263 579.31 32 18,538 347466 1.680 .954 .046 1853.80 10 18,538 121165 1.683 .954 .046

264 86.87 137 11,901 914976 2.481 .993 .007 135.24 88 11,901 585043 1.905 .972 .028

265 76.15 259 19,723 2699990 1.592 .944 .056 118.81 166 19,723 1726704 1.223 .889 .111

266 30.37 109 3,310 182170 .178 .571 .429 47.97 69 3,310 122696 1.071 .858 .142

267 63.00 578 36,415 10589408 .259 .602 .398 124.71 292 36,415 5428619 .624 .734 .266

268 54.52 67 3,653 123346 .112 .545 .455 91.33 40 3,653 80312 1.087 .861 .139

269 177.25 4 709 1986 1.388 .917 .083 709.00 1 709 556 .985 .838 .163

270 74.50 190 14,154 1356631 .213 .584 .416 138.77 102 14,154 718772 -.075 .470 .470

271 -- -- -- -- -- -- -- -- -- -- -- -- -- --

272 -- -- -- -- -- -- -- -- -- -- -- -- -- --

273 111.08 286 31,770 4558269 .098 .539 .461 190.24 167 31,770 2670299 .148 .559 .441

274 117.35 97 11,383 654439 3.163 .999 .001 223.20 51 11,383 350619 2.572 .995 .005

275 80.10 30 2,403 34232 -.477 .317 .317 184.85 13 2,403 11431 -1.675 .047 .047

276 146.75 44 6,457 143329 .103 .541 .459 379.82 17 6,457 48775 -.795 .213 .213

277 70.06 16 1,121 9677 .548 .708 .292 124.56 9 1,121 5400 .366 .643 .357

278 66.15 179 11,840 1088955 .640 .739 .261 122.06 97 11,840 615175 1.216 .888 .112

279 731.00 1 731 297 -.325 .373 .373 -- -- -- -- -- -- --

280 246.05 67 16,485 557749 .141 .556 .444 433.82 38 16,485 350093 1.257 .896 .104

281 98.11 45 4,415 106802 .873 .809 .191 191.96 23 4,415 49946 -.135 .446 .446

282 60.96 22 1,341 16632 1.036 .850 .150 149.00 9 1,341 6487 .390 .652 .348

283 83.33 233 19,415 2234035 -.325 .373 .373 176.50 110 19,415 1029971 -.644 .260 .260

284 107.14 89 9,535 489805 2.522 .994 .006 179.91 53 9,535 286762 1.701 .956 .044

285 50.76 641 32,536 10037785 -1.640 .051 .051 91.65 355 32,536 5544008 -1.306 .096 .096

286 148.29 252 37,369 4483974 -1.311 .095 .095 278.87 134 37,369 2378181 -1.005 .157 .157

287 130.43 14 1,826 12025 -.384 .351 .351 182.60 10 1,826 8214 -.550 .291 .291

288 89.07 148 13,182 936382 -.844 .199 .199 183.08 72 13,182 453364 -.656 .256 .256

Table 6. Summary of interoccurrence intervals for daily precipitation thresholds of 1.5 and 2.0 inches—Continued

Seq.

no.

Daily precipitation threshold of 1.5 inches and greater Daily precipitation threshold of 2.0 inches and greater

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue
148 Atlas of Interoccurrence Intervals for Selected Thresholds of Daily Precipitation in Texas 

289 162.00 7 1,134 2459 -1.743 .041 .041 378.00 3 1,134 1366 -.591 .277 .277

290 90.27 338 30,511 5169003 .078 .531 .469 186.04 164 30,511 2604859 .913 .819 .181

291 130.07 150 19,511 1406778 -.820 .206 .206 219.23 89 19,511 785504 -1.557 .060 .060

292 99.59 22 2,191 24303 .068 .527 .473 182.58 12 2,191 15353 1.007 .843 .157

293 68.99 512 35,323 9403766 1.565 .941 .059 113.22 312 35,323 5620063 .609 .729 .271

294 44.01 428 18,834 4212250 1.616 .947 .053 88.01 214 18,834 2140775 1.578 .943 .057

295 89.92 66 5,935 197473 .116 .546 .454 169.57 35 5,935 105887 .200 .579 .421

296 50.41 341 17,191 3104632 1.894 .971 .029 103.56 166 17,191 1522919 1.503 .934 .067

297 49.48 395 19,546 4086016 2.013 .978 .022 93.97 208 19,546 2103267 .866 .807 .193

298 76.90 133 10,227 701473 .628 .735 .265 189.39 54 10,227 284651 .393 .653 .347

299 -- -- -- -- -- -- -- -- -- -- -- -- -- --

300 323.80 15 4,857 39638 .591 .723 .277 607.13 8 4,857 18362 -.269 .394 .394

301 208.28 81 16,871 677145 -.140 .444 .444 468.64 36 16,871 299615 -.139 .445 .445

302 257.45 75 19,309 828262 2.158 .985 .015 715.15 27 19,309 292468 1.098 .864 .136

303 28.65 17 487 3395 -1.284 .100 .100 48.70 10 487 1995 -.990 .161 .161

304 66.80 375 25,051 4615472 -.583 .280 .280 132.55 189 25,051 2310189 -.575 .283 .283

305 53.59 29 1,554 21526 -.417 .338 .338 86.33 18 1,554 13137 -.446 .328 .328

306 54.47 683 37,205 12926597 .788 .784 .216 91.64 406 37,205 7704052 .700 .758 .242

307 167.67 126 21,126 1460581 1.894 .971 .029 346.33 61 21,126 735308 1.910 .972 .028

308 55.71 319 17,772 2836392 .019 .508 .492 102.14 174 17,772 1579995 .500 .691 .309

309 129.67 9 1,167 5787 .530 .702 .298 194.50 6 1,167 4379 1.064 .856 .144

310 70.52 44 3,103 56565 -1.969 .024 .024 155.15 20 3,103 28144 -.720 .236 .236

311 126.80 30 3,804 57320 .043 .517 .483 951.00 4 3,804 8036 .195 .577 .423

312 73.52 252 18,527 2577817 2.867 .998 .002 147.04 126 18,527 1322168 2.581 .995 .005

313 91.30 27 2,465 28991 -1.159 .123 .123 176.07 14 2,465 13469 -1.422 .078 .078

314 62.83 18 1,131 10149 -.022 .491 .491 161.57 7 1,131 3770 -.218 .414 .414

315 43.05 434 18,684 4429540 3.338 1.000 0 80.53 232 18,684 2474209 3.735 1.000 0

316 152.23 13 1,979 11345 -.737 .231 .231 329.83 6 1,979 7379 1.031 .849 .151

317 162.70 10 1,627 8533 .268 .606 .394 271.17 6 1,627 3544 -1.162 .123 .123

318 170.08 97 16,498 766236 -.723 .235 .235 358.65 46 16,498 363966 -.480 .316 .316

319 124.60 30 3,738 54640 -.242 .404 .404 219.88 17 3,738 26800 -1.118 .132 .132

320 1336.00 6 8,016 18095 -1.050 .147 .147 4008.00 2 8,016 3290 -1.444 .074 .074

321 62.64 331 20,733 3506866 .694 .756 .244 120.54 172 20,733 1819906 .470 .681 .319

322 63.97 196 12,538 1283637 1.084 .861 .139 100.30 125 12,538 869459 2.121 .983 .017

323 69.66 77 5,364 208264 .129 .551 .449 178.80 30 5,364 78675 -.211 .417 .417

324 74.36 425 31,602 6964578 1.325 .907 .093 151.21 209 31,602 3685380 2.904 .998 .002

325 224.16 19 4,259 30667 -1.827 .034 .034 425.90 10 4,259 20746 -.141 .444 .444

326 42.16 154 6,492 497485 -.103 .459 .459 82.18 79 6,492 273644 1.033 .849 .151

327 97.90 83 8,126 329378 -.367 .357 .357 198.20 41 8,126 142278 -1.618 .053 .053

328 121.88 8 975 4257 .448 .673 .327 487.50 2 975 1122 .369 .644 .356

329 35.70 324 11,566 1869716 -.066 .474 .474 60.24 192 11,566 1044374 -1.426 .077 .077

330 48.25 757 36,526 14126929 1.040 .851 .149 94.87 385 36526 7131873 .486 .687 .313

331 133.96 50 6,698 179571 .887 .812 .188 279.08 24 6,698 88325 .839 .799 .201

332 113.46 281 31,881 4501781 .146 .558 .442 192.05 166 31,881 2809226 1.376 .915 .085

333 60.73 353 21,436 3831266 0.411 .660 .340 117.78 182 21,436 1968974 0.219 .587 .413

334 195.47 79 15,442 693338 2.104 .982 .018 514.73 30 15,442 270027 1.573 .942 .058

335 224.43 99 22,219 1016485 -1.306 .096 .096 435.67 51 22,219 475911 -1.980 .024 .024

336 86.25 24 2,070 24827 -.004 .498 .498 188.18 11 2,070 7935 -1.741 .041 .041

Table 6. Summary of interoccurrence intervals for daily precipitation thresholds of 1.5 and 2.0 inches—Continued

Seq.

no.

Daily precipitation threshold of 1.5 inches and greater Daily precipitation threshold of 2.0 inches and greater

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue
Table 6 149

337 91.75 120 11,010 608871 -1.486 .069 .069 220.20 50 11,010 273751 -.067 .473 .473

338 94.71 61 5,777 175788 -.032 .487 .487 231.08 25 5,777 77831 .674 .750 .250

339 42.25 115 4,859 308399 1.928 .973 .027 79.66 61 4,859 151644 .314 .623 .377

340 65.00 96 6,240 306610 .402 .656 .344 127.35 49 6,240 151039 -.146 .442 .442

341 226.44 43 9,737 236400 1.468 .929 .071 389.48 25 9,737 149054 1.945 .974 .026

342 195.24 21 4,100 54229 2.061 .980 .020 410.00 10 4,100 32206 3.128 .999 .001

343 67.56 188 12,702 1197007 .060 .524 .476 125.76 101 12,702 679530 1.033 .849 .151

344 77.54 444 34,428 8089324 2.131 .983 .017 140.52 245 34,428 4427337 1.349 .911 .089

345 48.50 10 485 2281 -.325 .373 .373 121.25 4 485 988 .064 .526 .474

346 207.00 104 21,528 1032715 -1.369 .086 .086 422.12 51 21,528 519469 -.665 .253 .253

347 198.67 6 1,192 3861 .338 .632 .368 397.33 3 1,192 1918 .218 .586 .414

348 122.70 91 11,166 529736 .705 .760 .240 248.13 45 11,166 266282 .696 .757 .243

349 116.26 96 11,161 539908 .132 .553 .447 223.22 50 11,161 298633 .861 .805 .195

350 104.38 270 28,183 3891903 .652 .743 .257 242.96 116 28,183 1677162 .486 .686 .314

351 120.78 32 3,865 65460 .574 .717 .283 227.35 17 3,865 31382 -.320 .375 .375

352 106.20 10 1,062 5195 -.119 .453 .453 132.75 8 1,062 3922 -.376 .353 .353

353 48.61 67 3,257 113461 .565 .714 .286 125.27 26 3,257 41421 -.192 .424 .424

354 75.56 91 6,876 324413 .610 .729 .271 156.27 44 6,876 158846 .575 .717 .283

355 76.51 146 11,170 801966 -.345 .365 .365 134.58 83 11,170 449905 -.465 .321 .321

356 118.52 302 35,793 5385287 -.108 .457 .457 192.44 186 35,793 3186521 -1.009 .156 .156

357 100.60 314 31,587 4865988 -.577 .282 .282 214.88 147 31,587 2197786 -1.120 .131 .131

358 116.57 162 18,884 1524585 -.072 .471 .471 222.17 85 18,884 794926 -.152 .440 .440

359 148.00 15 2,220 20756 1.654 .951 .049 277.50 8 2,220 13174 2.369 .991 .009

360 72.40 10 724 2913 -1.070 .142 .142 181.00 4 724 1256 -.459 .323 .323

361 150.00 1 150 99 .554 .710 .290 -- -- -- -- -- -- --

362 56.61 375 21,229 3894798 -.722 .235 .235 103.05 206 21,229 2215254 .326 .628 .372

363 44.65 49 2,188 51158 -.554 .290 .290 84.15 26 2,188 26628 -.564 .286 .286

364 49.17 195 9,588 966864 .829 .796 .204 78.59 122 9,588 583711 -.038 .485 .485

365 49.84 447 22,280 4960014 -.144 .443 .443 95.21 234 22,280 2588776 -.183 .427 .427

366 51.53 49 2,525 63712 .363 .642 .358 52.60 48 2,525 62638 .404 .657 .343

367 54.45 212 11,543 1246887 .481 .685 .315 103.99 111 11,543 643405 .079 .531 .469

368 123.91 68 8,426 274666 -.589 .278 .278 210.65 40 8,426 151435 -1.111 .133 .133

369 -- -- -- -- -- -- -- -- -- -- -- -- -- --

370 1307.40 5 6,537 10121 -1.474 .070 .070 3268.50 2 6,537 3833 -1.013 .156 .156

371 939.00 21 19,719 169542 -1.438 .075 .075 4929.75 4 19,719 38667 -.068 .473 .473

372 156.85 52 8,156 235042 1.354 .912 .088 429.26 19 8,156 95112 1.718 .957 .043

373 93.00 2 186 235 .645 .741 .259 93.00 2 186 235 .645 .741 .259

374 174.80 5 874 2870 1.214 .888 .112 291.33 3 874 2097 1.799 .964 .036

375 164.94 65 10,721 372105 .949 .829 .171 345.84 31 10,721 164365 -.105 .458 .458

376 171.18 17 2,910 30705 1.724 .958 .042 485.00 6 2,910 10235 .731 .768 .232

377 95.53 190 18,150 1819494 1.319 .906 .094 187.11 97 18,150 940776 1.172 .879 .121

378 76.13 191 14,540 1425014 .628 .735 .265 132.18 110 14,540 810775 .252 .599 .401

379 36.20 5 181 507 .467 .680 .320 181.00 1 181 138 .909 .818 .182

380 119.00 12 1,428 9270 .492 .688 .312 142.80 10 1,428 7387 .190 .575 .425

381 48.34 393 18,998 3857071 1.140 .873 .127 86.75 219 18,998 2237040 1.932 .973 .027

382 74.00 4 296 507 -.497 .309 .309 74.00 4 296 507 -.497 .309 .309

383 111.51 291 32,450 5155415 2.716 .997 .003 178.30 182 32,450 3149701 1.557 .940 .060

384 115.04 71 8,168 281314 -.435 .332 .332 204.20 40 8,168 164531 .079 .531 .469

Table 6. Summary of interoccurrence intervals for daily precipitation thresholds of 1.5 and 2.0 inches—Continued

Seq.

no.

Daily precipitation threshold of 1.5 inches and greater Daily precipitation threshold of 2.0 inches and greater

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue
150 Atlas of Interoccurrence Intervals for Selected Thresholds of Daily Precipitation in Texas 

385 60.43 285 17,222 2406362 -.569 .285 .285 112.56 153 17,222 1323393 .096 .538 .462

386 61.00 4 244 390 -.696 .243 .243 244.00 1 244 236 1.619 .947 .053

387 83.24 25 2,081 25807 -.068 .473 .473 189.18 11 2,081 9913 -.769 .221 .221

388 66.60 37 2,464 49021 .794 .786 .214 136.89 18 2,464 22695 .172 .568 .432

389 60.50 6 363 1156 .261 .603 .397 90.75 4 363 1030 1.451 .927 .073

390 36.87 474 17,476 4239364 .888 .813 .187 69.35 252 17,476 2222616 .258 .602 .398

391 84.51 189 15,972 1518345 .142 .556 .444 164.66 97 15,972 777028 .053 .521 .479

392 79.54 13 1,034 5010 -1.590 .056 .056 94.00 11 1,034 3682 -2.025 .021 .021

393 882.83 12 10,594 79136 1.470 .929 .071 1324.25 8 10,594 44093 .199 .579 .421

394 -- -- -- -- -- -- -- -- -- -- -- -- -- --

395 80.66 113 9,115 572006 2.038 .979 .021 128.38 71 9,115 351349 1.252 .895 .105

396 53.38 369 19,696 3763569 1.187 .882 .118 106.47 185 19,696 1782911 -.504 .307 .307

397 146.81 97 14,241 655769 -.862 .194 .194 249.84 57 14,241 377261 -.922 .178 .178

398 102.17 331 33,819 5811676 1.208 .887 .113 183.80 184 33,819 3260653 1.127 .870 .130

399 82.43 238 19,618 2356859 .255 .601 .399 153.27 128 19,618 1208789 -.730 .233 .233

400 48.79 395 19,271 3846362 .365 .642 .358 89.63 215 19,271 2123773 .639 .739 .261

401 160.53 36 5,779 86302 -1.770 .038 .038 275.19 21 5,779 44363 -2.134 .016 .016

402 81.00 3 243 503 1.140 .873 .127 121.50 2 243 263 .202 .580 .420

403 63.84 212 13,535 1368183 -1.169 .121 .121 123.05 110 13,535 775829 .766 .778 .222

404 62.64 329 20,610 3502365 1.038 .850 .150 127.22 162 20,610 1721999 .695 .756 .244

405 126.43 94 11,884 621661 1.898 .971 .029 237.68 50 11,884 336400 1.620 .947 .053

406 71.57 303 21,685 3498207 1.954 .975 .025 134.69 161 21,685 1930907 2.332 .990 .010

407 65.05 57 3,708 94293 -1.409 .079 .079 168.55 22 3,708 42175 .276 .609 .391

408 63.70 536 34,142 9573712 1.857 .968 .032 121.94 280 34,142 5071652 1.769 .962 .038

409 608.00 2 1,216 1263 .095 .538 .462 1216.00 1 1,216 423 -.527 .299 .299

410 54.13 266 14,398 1979834 .957 .831 .169 105.87 136 14,398 1010121 .641 .739 .261

411 137.71 139 19,141 1382074 .795 .787 .213 290.02 66 19,141 699169 1.504 .934 .066

412 63.17 220 13,897 1678240 2.514 .994 .006 122.98 113 13,897 922857 3.228 .999 .001

413 84.96 355 30,162 5316140 -.229 .409 .409 157.92 191 30,162 2806641 -.614 .270 .270

414 55.21 62 3,423 114868 1.125 .870 .130 106.97 32 3,423 58059 .589 .722 .278

415 167.89 128 21,490 1335196 -.572 .284 .284 383.75 56 21,490 591260 -.225 .411 .411

416 161.27 120 19,352 1165926 .079 .531 .469 365.13 53 19,352 450823 -1.525 .064 .064

417 76.80 40 3,072 69933 1.514 .935 .065 219.43 14 3,072 30731 2.781 .997 .003

418 169.56 147 24,925 2029638 2.266 .988 .012 361.23 69 24,925 959655 1.669 .952 .048

419 73.33 309 22,658 3256270 -2.126 .017 .017 137.32 165 22,658 1704349 -1.963 .025 .025

420 156.87 122 19,138 1223307 .916 .820 .180 324.37 59 19,138 634310 1.643 .950 .050

421 458.69 68 31,191 1066494 .081 .532 .468 1356.13 23 31,191 374814 .373 .646 .355

422 609.95 19 11,589 78496 -2.167 .015 .015 827.79 14 11,589 54848 -2.099 .018 .018

423 126.04 92 11,596 507837 -.797 .213 .213 218.79 53 11,596 305590 -.070 .472 .472

424 -- -- -- -- -- -- -- -- -- -- -- -- -- --

425 327.11 65 21,262 697772 .137 .554 .446 644.30 33 21,262 325711 -.712 .238 .238

426 270.71 66 17,867 543110 -1.110 .134 .134 496.31 36 17,867 269152 -1.695 .045 .045

427 -- -- -- -- -- -- -- -- -- -- -- -- -- --

428 94.08 51 4,798 137603 1.542 .938 .062 137.09 35 4,798 97984 1.711 .956 .044

429 79.59 68 5,412 189348 0.415 .661 .339 174.58 31 5,412 80472 -0.393 .347 .347

430 84.10 106 8,915 500952 1.074 .859 .141 151.10 59 8,915 310930 2.425 .992 .008

431 68.86 56 3,856 109102 .136 .554 .446 167.65 23 3,856 37593 -1.265 .103 .103

432 44.33 196 8,688 797648 -1.532 .063 .063 79.71 109 8,688 454199 -.737 .231 .231

Table 6. Summary of interoccurrence intervals for daily precipitation thresholds of 1.5 and 2.0 inches—Continued

Seq.

no.

Daily precipitation threshold of 1.5 inches and greater Daily precipitation threshold of 2.0 inches and greater

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue
Table 6 151

433 97.35 281 27,354 3821694 -.163 .435 .435 182.36 150 27,354 2077289 .266 .605 .395

434 62.37 218 13,597 1509906 .480 .684 .316 123.61 110 13,597 787311 .959 .831 .169

435 73.79 14 1,033 8899 1.495 .933 .067 114.78 9 1,033 6778 2.380 .991 .009

436 90.51 321 29,054 4986936 2.155 .984 .016 168.92 172 29,054 2584073 .777 .781 .219

437 40.07 632 25,322 8194629 1.050 .853 .147 65.60 386 25,322 5000521 .789 .785 .215

438 81.89 228 18,671 2239279 1.361 .913 .087 142.53 131 18,671 1297048 1.201 .885 .115

439 97.19 84 8,164 321410 -.994 .160 .160 189.86 43 8,164 170220 -.343 .366 .366

440 95.90 97 9,302 473618 .850 .802 .198 157.66 59 9,302 295141 1.005 .843 .157

441 263.70 90 23,733 1109547 .640 .739 .261 641.43 37 23,733 391904 -1.132 .129 .129

442 61.99 206 12,769 1416144 1.908 .972 .028 115.04 111 12,769 780582 1.852 .968 .032

443 69.08 188 12,987 1215450 -.104 .459 .459 154.61 84 12,987 535384 -.293 .385 .385

444 115.21 14 1,613 12005 .410 .659 .341 322.60 5 1,613 5225 1.145 .874 .126

445 153.12 125 19,140 1251821 .900 .816 .184 348.00 55 19,140 525392 -.023 .491 .491

446 90.54 13 1,177 7865 .175 .570 .430 235.40 5 1,177 3333 .514 .696 .304

447 158.19 145 22,938 1563190 -1.252 .105 .105 358.41 64 22,938 647710 -1.629 .052 .052

448 69.29 455 31,527 6999417 -.891 .187 .187 135.31 233 31,527 3447453 -1.623 .052 .052

449 50.64 105 5,317 262547 -1.055 .146 .146 91.67 58 5,317 151292 -.248 .402 .402

450 58.17 353 20,533 3908194 2.551 .995 .005 102.15 201 20,533 2179221 1.376 .916 .084

451 63.93 87 5,562 245579 .243 .596 .404 111.24 50 5,562 146492 .656 .744 .256

452 101.33 3 304 371 -.559 .288 .288 152.00 2 304 287 -.137 .445 .445

453 262.88 8 2,103 4986 -1.995 .023 .023 701.00 3 2,103 3069 -.081 .468 .468

454 194.99 163 31,784 2652250 .528 .701 .299 392.40 81 31,784 1244206 -.521 .301 .301

455 221.75 4 887 1916 .277 .609 .391 443.50 2 887 1029 .392 .653 .348

456 -- -- -- -- -- -- -- -- -- -- -- -- -- --

457 68.20 5 341 1242 1.770 .962 .038 113.67 3 341 640 .754 .774 .226

458 41.21 151 6,223 473007 .144 .557 .443 73.21 85 6,223 270962 .392 .652 .348

459 62.28 18 1,121 10489 .291 .615 .385 93.42 12 1,121 6805 .071 .528 .472

460 69.94 468 32,732 7361236 -1.458 .072 .072 126.87 258 32,732 3919545 -1.996 .023 .023

461 89.49 344 30,785 5418453 .749 .773 .227 165.51 186 30,785 2747502 -.953 .170 .170

462 72.41 245 17,740 2226419 .665 .747 .253 133.38 133 17,740 1168366 -.192 .424 .424

463 64.46 116 7,477 490026 2.424 .992 .008 124.62 60 7,477 230475 .369 .644 .356

464 59.37 379 22,500 4228074 -.282 .389 .389 109.22 206 22,500 2272394 -.484 .314 .314

465 61.44 32 1,966 34350 .901 .816 .184 109.22 18 1,966 19858 .899 .816 .184

466 52.26 502 26,233 6643780 .350 .637 .363 95.05 276 26,233 3778116 1.256 .895 .105

467 381.48 29 11,063 167402 .406 .658 .342 1580.43 7 11,063 41365 .313 .623 .377

468 33.10 30 993 10735 -2.650 .004 .004 58.41 17 993 5594 -2.408 .008 .008

469 50.62 194 9,821 913009 -1.004 .158 .158 99.20 99 9,821 469536 -.589 .278 .278

470 91.00 1 91 45 -.019 .492 .492 -- -- -- -- -- -- --

471 71.59 187 13,388 1299324 .900 .816 .184 143.96 93 13,388 628076 .149 .559 .441

472 46.83 72 3,372 124820 .415 .661 .339 80.29 42 3,372 78090 1.154 .876 .124

473 73.95 260 19,226 2788580 3.232 .999 .001 141.37 136 19,226 1388330 1.251 .894 .106

474 96.46 261 25,176 3441019 1.325 .907 .093 215.18 117 25,176 1509061 .461 .678 .322

475 69.93 457 31,959 7769221 2.366 .991 .009 119.25 268 31,959 4612940 2.188 .986 .014

476 57.90 315 18,237 3007785 1.450 .926 .074 94.01 194 18,237 1761852 -.097 .461 .461

477 75.02 56 4,201 138656 2.317 .990 .010 150.04 28 4,201 75056 2.531 .994 .006

478 72.07 320 23,063 3791807 .854 .803 .197 133.31 173 23,063 2059532 .738 .770 .230

479 44.80 40 1,792 29901 -1.815 .035 .035 81.46 22 1,792 15241 -1.843 .033 .033

480 64.59 88 5,684 258124 .522 .699 .301 107.25 53 5,684 154465 .321 .626 .374

Table 6. Summary of interoccurrence intervals for daily precipitation thresholds of 1.5 and 2.0 inches—Continued

Seq.

no.

Daily precipitation threshold of 1.5 inches and greater Daily precipitation threshold of 2.0 inches and greater

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue
152 Atlas of Interoccurrence Intervals for Selected Thresholds of Daily Precipitation in Texas 

481 43.17 293 12,650 1979310 2.017 .978 .022 75.30 168 12,650 1181073 2.503 .994 .006

482 77.27 48 3,709 86146 -.387 .349 .349 137.37 27 3,709 46938 -.563 .287 .287

483 70.53 45 3,174 77409 .975 .835 .165 144.27 22 3,174 36221 .304 .619 .381

484 76.00 36 2,736 48753 -.105 .458 .458 109.44 25 2,736 32591 -.407 .342 .342

485 84.80 10 848 2912 -1.716 .043 .043 212.00 4 848 656 -2.124 .017 .017

486 88.50 393 34,779 6959733 .631 .736 .264 177.44 196 34,779 3605822 1.405 .920 .080

487 81.91 128 10,484 672203 .036 .514 .486 156.48 67 10,484 374060 .922 .822 .178

488 287.12 98 28,138 1427256 .603 .727 .273 639.50 44 28,138 576943 -.781 .217 .217

489 74.06 157 11,627 967254 1.297 .903 .097 149.06 78 11,627 484660 1.053 .854 .146

490 71.58 109 7,802 445758 .874 .809 .191 152.98 51 7,802 237513 2.398 .992 .008

491 53.66 238 12,770 1605934 1.518 .935 .065 107.31 119 12,770 785927 .649 .742 .258

492 72.30 347 25,088 4212568 -1.039 .149 .149 140.94 178 25,088 2223798 -.094 .463 .463

493 53.71 664 35,661 12251265 1.552 .940 .060 94.84 376 35,661 7013373 1.549 .939 .061

494 49.57 86 4,263 187503 .368 .643 .357 85.26 50 4,263 109564 .344 .634 .366

495 42.65 477 20,344 5293694 3.443 1.000 0 79.78 255 20,344 2886619 3.122 .999 .001

496 184.25 117 21,557 1167391 -1.392 .082 .082 365.37 59 21,557 463890 -3.599 0 0

497 815.00 1 815 465 .244 .597 .403 815.00 1 815 465 .244 .597 .403

498 61.32 311 19,069 3122212 1.617 .947 .053 123.03 155 19,069 1566826 1.298 .903 .097

499 111.62 159 17,748 1451606 .629 .735 .265 253.54 70 17,748 621840 .015 .506 .494

500 88.92 13 1,156 10756 2.695 .996 .004 231.20 5 1,156 4075 1.588 .944 .056

501 76.30 67 5,112 162934 -.689 .246 .246 146.06 35 5,112 85929 -.404 .343 .343

502 50.70 603 30,570 9701944 2.239 .987 .013 95.23 321 30,570 5320771 2.620 .996 .004

503 145.71 42 6,120 122252 -.547 .292 .292 278.18 22 6,120 57147 -1.228 .110 .110

504 230.19 16 3,683 30571 .260 .603 .397 334.82 11 3,683 19432 -.234 .408 .408

505 153.00 7 1,071 3408 -.416 .339 .339 535.50 2 1,071 386 -1.567 .059 .059

506 63.07 593 37,401 11882537 3.017 .999 .001 111.98 334 37,401 6796651 2.791 .997 .003

507 33.24 42 1,396 33420 1.571 .942 .058 60.70 23 1,396 16634 .300 .618 .382

508 86.79 183 15,882 1463501 .166 .566 .434 206.26 77 15,882 594791 -.414 .339 .339

509 118.14 216 25,519 2633674 -1.130 .129 .129 274.40 93 25,519 1107088 -1.120 .131 .131

510 233.11 9 2,098 11505 1.136 .872 .128 299.71 7 2,098 8286 .589 .722 .278

511 43.95 423 18,591 4411782 4.347 1.000 0 83.37 223 18,591 2429865 4.454 1.000 0

512 97.32 324 31,532 5073560 -.211 .416 .416 166.84 189 31,532 2934804 -.359 .360 .360

513 96.85 220 21,306 2314913 -.315 .376 .376 191.95 111 21,306 1260821 1.209 .887 .113

514 -- -- -- -- -- -- -- -- -- -- -- -- -- --

515 223.39 72 16,084 550659 -.720 .236 .236 554.62 29 16,084 247196 .559 .712 .288

516 343.88 8 2,751 13821 1.254 .895 .105 1375.50 2 2,751 2924 .154 .561 .439

517 219.78 89 19,560 882444 .226 .589 .411 489.00 40 19,560 435456 1.239 .892 .108

518 123.53 297 36,688 5598504 .824 .795 .205 286.63 128 36,688 2310916 -.310 .378 .378

519 130.78 59 7,716 251389 1.389 .918 .082 308.64 25 7,716 104564 .729 .767 .233

520 167.50 4 670 1005 -.866 .193 .193 670.00 1 670 641 1.582 .943 .057

521 45.93 388 17,822 3479285 .215 .585 .415 90.47 197 17,822 1834622 1.096 .863 .137

522 86.07 86 7,402 370391 2.630 .996 .004 189.80 39 7,402 155320 .823 .795 .205

523 140.89 27 3,804 60708 1.639 .949 .051 237.75 16 3,804 36191 1.311 .905 .095

524 608.75 4 2,435 4812 -.041 .484 .484 -- -- -- -- -- -- --

525 -- -- -- -- -- -- -- -- -- -- -- -- -- --

526 115.06 283 32,561 4606957 -0.003 .499 .499 206.08 158 32,561 2538262 -0.288 .387 .387

527 36.37 239 8,692 1144122 2.718 .997 .003 67.38 129 8,692 617864 2.008 .978 .022

528 36.29 87 3,157 130251 -.833 .203 .203 63.14 50 3,157 78968 .007 .503 .497

Table 6. Summary of interoccurrence intervals for daily precipitation thresholds of 1.5 and 2.0 inches—Continued

Seq.

no.

Daily precipitation threshold of 1.5 inches and greater Daily precipitation threshold of 2.0 inches and greater

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue
Table 6 153

529 57.92 200 11,583 1276963 2.509 .994 .006 104.35 111 11,583 710558 1.922 .973 .027

530 47.66 716 34,124 12739084 1.983 .976 .024 92.48 369 34,124 6559215 1.392 .918 .082

531 63.00 101 6,363 341049 1.068 .857 .143 109.71 58 6,363 199405 1.064 .856 .144

532 87.30 413 36,056 7627113 .858 .805 .195 183.03 197 36,056 3610461 .404 .657 .343

533 220.15 117 25,757 1394414 -1.397 .081 .081 415.44 62 25,757 764298 -.584 .280 .280

534 98.60 10 986 4410 -.578 .282 .282 328.67 3 986 1926 .907 .818 .182

535 72.84 576 41,954 11975006 -.371 .355 .355 140.31 299 41,954 6101876 -.813 .208 .208

536 75.50 2 151 48 -1.671 .047 .047 -- -- -- -- -- -- --

537 81.29 392 31,864 6532502 1.577 .943 .057 168.59 189 31,864 3081298 .555 .710 .290

538 120.53 19 2,290 18431 -1.154 .124 .124 190.83 12 2,290 10566 -1.386 .083 .083

539 132.39 149 19,726 1361803 -1.551 .061 .061 308.22 64 19,726 612100 -.420 .337 .337

540 83.30 20 1,666 20308 1.696 .955 .045 151.46 11 1,666 10183 .640 .739 .261

541 65.98 531 35,035 8950532 -1.507 .066 .066 122.07 287 35,035 4790591 -1.383 .083 .083

542 74.00 16 1,184 9132 -.249 .402 .402 118.40 10 1,184 6149 .212 .584 .416

543 270.10 31 8,373 129092 -.051 .480 .480 523.31 16 8,373 82680 1.623 .948 .052

544 82.85 354 29,330 5247177 .350 .637 .363 143.78 204 29,330 2995261 .030 .512 .488

545 113.47 74 8,397 314760 .195 .577 .423 209.93 40 8,397 145772 -1.446 .074 .074

546 49.22 638 31,403 10165564 .646 .741 .259 85.33 368 31,403 5975493 1.135 .872 .128

547 104.44 169 17,650 1412539 -1.191 .117 .117 191.85 92 17,650 770160 -.854 .197 .197

548 47.51 276 13,112 1875409 1.049 .853 .147 85.14 154 13,112 1013172 .076 .530 .470

549 -- -- -- -- -- -- -- -- -- -- -- -- -- --

550 41.90 20 838 8944 .521 .699 .301 93.11 9 838 4115 .474 .682 .318

551 53.78 102 5,486 302053 1.392 .918 .082 94.59 58 5,486 169673 .877 .810 .190

552 50.17 390 19,567 4085051 2.416 .992 .008 93.62 209 19,567 2290779 3.013 .999 .001

553 -- -- -- -- -- -- -- -- -- -- -- -- -- --

554 44.57 267 11,901 1603368 .260 .603 .397 82.65 144 11,901 863549 .162 .564 .436

555 -- -- -- -- -- -- -- -- -- -- -- -- -- --

556 39.83 502 19,994 5376936 2.772 .997 .003 70.15 285 19,994 3075740 2.326 .990 .010

557 54.80 5 274 635 -.283 .389 .389 91.33 3 274 396 -.110 .456 .456

558 40.94 52 2,129 59040 .832 .797 .203 78.85 27 2,129 29186 .139 .555 .445

559 97.33 6 584 1374 -.915 .180 .180 146.00 4 584 1112 -.166 .434 .434

560 244.00 1 244 54 -.965 .167 .167 -- -- -- -- -- -- --

561 40.71 437 17,792 4154022 2.482 .993 .007 77.36 230 17,792 2298751 3.244 .999 .001

562 40.97 505 20,691 5535609 2.318 .990 .010 80.20 258 20,691 2800173 1.366 .914 .086

563 44.11 383 16,893 3423390 1.974 .976 .024 72.19 234 16,893 1951135 -.340 .367 .367

564 46.07 412 18,979 4150241 2.163 .985 .015 93.03 204 18,979 2127756 2.452 .993 .007

565 39.49 124 4,897 324865 1.350 .911 .089 63.60 77 4,897 211576 1.858 .968 .032

566 42.44 353 14,981 2830420 2.293 .989 .011 76.05 197 14,981 1522338 .770 .779 .221

567 86.20 102 8,792 583656 5.277 0 0 151.59 58 8,792 331088 3.938 1.000 0

568 41.95 377 15,815 3193436 2.395 .992 .008 85.03 186 15,815 1585085 1.836 .967 .033

569 55.53 166 9,218 728435 -1.069 .143 .143 97.03 95 9,218 413382 -.944 .173 .173

570 29.10 125 3,637 239424 1.032 .849 .151 46.63 78 3,637 150781 .964 .832 .168

571 45.79 396 18,133 3984926 3.788 1.000 0 90.67 200 18,133 2036025 3.009 .999 .001

572 69.02 185 12,769 1127909 -1.062 .144 .144 138.79 92 12769 599324 .338 .632 .368

573 129.26 39 5,041 96976 -0.146 .442 .442 265.32 19 5,041 47640 -0.039 .484 .484

574 46.90 238 11,163 1419545 1.833 .967 .033 74.92 149 11,163 948182 2.963 .998 .002

575 101.75 172 17,501 1521810 .252 .600 .400 203.50 86 17501 800845 1.031 .849 .151

576 75.35 48 3,617 84973 -.254 .400 .400 109.61 33 3,617 56946 -.456 .324 .324

Table 6. Summary of interoccurrence intervals for daily precipitation thresholds of 1.5 and 2.0 inches—Continued

Seq.

no.

Daily precipitation threshold of 1.5 inches and greater Daily precipitation threshold of 2.0 inches and greater

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue
154 Atlas of Interoccurrence Intervals for Selected Thresholds of Daily Precipitation in Texas 

577 80.73 230 18,568 2367091 2.851 .998 .002 141.74 131 18,568 1374639 2.583 .995 .005

578 47.74 422 20,145 4293089 .356 .639 .361 95.47 211 20,145 2237755 1.331 .908 .092

579 81.92 172 14,090 1198770 -.243 .404 .404 156.56 90 14,090 587509 -1.206 .114 .114

580 73.00 1 73 57 .973 .835 .165 -- -- -- -- -- -- --

581 33.83 70 2,368 82222 -.115 .454 .454 64.00 37 2,368 43995 .045 .518 .482

582 73.10 253 18,495 2452698 1.332 .908 .092 141.18 131 18,495 1366602 2.539 .994 .006

583 261.00 62 16,182 575087 1.997 .977 .023 522.00 31 16,182 317733 2.573 .995 .005

584 61.00 4 244 542 .383 .649 .351 -- -- -- -- -- -- --

585 115.18 114 13,130 702580 -1.133 .129 .129 205.16 64 13,130 382910 -1.229 .110 .110

586 -- -- -- -- -- -- -- -- -- -- -- -- -- --

587 70.21 52 3,651 102509 .998 .841 .159 135.22 27 3,651 53098 .696 .757 .243

588 92.94 92 8,550 362292 -1.310 .095 .095 198.84 43 8,550 169854 -.863 .194 .194

589 58.51 112 6,553 398684 1.584 .943 .057 96.37 68 6,553 243602 1.333 .909 .091

590 52.86 7 370 1866 2.021 .978 .022 123.33 3 370 827 1.470 .929 .071

591 57.08 64 3,653 119785 .343 .634 .366 117.84 31 3,653 59732 .530 .702 .298

592 83.94 263 22,076 2917305 .139 .555 .445 159.97 138 22,076 1472222 -.682 .248 .248

593 48.63 319 15,514 2685192 2.634 .996 .004 100.09 155 15,514 1294899 1.660 .952 .048

594 48.55 121 5,874 361635 .336 .631 .369 96.30 61 5,874 186915 .586 .721 .279

595 99.20 93 9,226 438001 .350 .637 .363 205.02 45 9,226 178935 -1.604 .054 .054

596 65.92 390 25,710 5123330 .750 .773 .227 147.76 174 25,710 2388432 1.549 .939 .061

597 37.61 547 20,570 6005927 2.736 .997 .003 65.93 312 20,570 3412787 1.944 .974 .026

598 37.39 28 1,047 13388 -.794 .214 .214 74.79 14 1,047 5881 -1.280 .100 .100

599 135.11 131 17,699 1280131 2.067 .981 .019 256.51 69 17,699 661420 1.197 .884 .116

600 63.42 308 19,532 3101272 .943 .827 .173 111.61 175 19,532 1713560 .061 .524 .476

601 47.46 681 32,319 10889829 -.472 .319 .319 95.62 338 32,319 5290585 -.999 .159 .159

602 57.38 268 15,379 2042435 -.253 .400 .400 99.86 154 15,379 1177071 -.129 .449 .449

603 63.53 98 6,226 339015 1.908 .972 .028 97.28 64 6,226 215987 1.165 .878 .122

604 71.38 172 12,277 1101794 .989 .839 .161 133.45 92 12,277 591391 .784 .783 .217

605 177.43 35 6,210 115787 .671 .749 .251 326.84 19 6,210 71221 1.565 .941 .059

606 169.87 31 5,266 95983 1.697 .955 .045 239.36 22 5,266 69110 1.569 .942 .058

607 155.80 25 3,895 58426 1.732 .958 .042 432.78 9 3,895 20122 .769 .779 .221

608 89.29 237 21,162 2468317 -.419 .338 .338 162.79 130 21,162 1399777 .348 .636 .364

609 263.18 11 2,895 16205 .102 .541 .459 579.00 5 2,895 6899 -.181 .428 .428

610 100.62 303 30,487 4386732 -1.515 .065 .065 194.19 157 30,487 2200967 -1.744 .041 .041

611 164.38 50 8,219 218218 .760 .776 .224 342.46 24 8,219 110069 .984 .837 .163

612 150.42 24 3,610 56350 2.552 .995 .005 277.69 13 3,610 29443 1.591 .944 .056

613 68.90 10 689 2348 -1.744 .041 .041 98.43 7 689 1457 -1.814 .035 .035

614 145.83 23 3,354 36057 -.541 .294 .294 258.00 13 3,354 20383 -.406 .342 .342

615 61.00 1 61 47 .937 .826 .174 61.00 1 61 47 .937 .826 .174

616 85.36 22 1,878 19209 -.570 .284 .284 104.33 18 1,878 15105 -.781 .217 .217

617 38.96 45 1,753 27472 -3.526 0 0 67.42 26 1,753 15287 -2.907 .002 .002

618 43.73 472 20,642 5334421 3.576 1.000 0 86.37 239 20,642 2707437 2.613 .996 .004

619 84.15 338 28,443 4640461 -1.102 .135 .135 153.75 185 28,443 2508320 -1.098 .136 .136

620 77.44 9 697 3676 .894 .814 .186 -- -- -- -- -- -- --

621 52.71 313 16,498 2799898 2.587 .995 .005 94.82 174 16,498 1478794 0.692 .755 .245

622 59.71 606 36,185 11041040 .299 .618 .382 113.43 319 36,185 5825553 .290 .614 .386

623 92.05 80 7,364 291267 -.173 .431 .431 179.61 41 7,364 143238 -.567 .285 .285

624 48.60 40 1,944 36151 -.769 .221 .221 77.76 25 1,944 24962 .236 .593 .407

Table 6. Summary of interoccurrence intervals for daily precipitation thresholds of 1.5 and 2.0 inches—Continued

Seq.

no.

Daily precipitation threshold of 1.5 inches and greater Daily precipitation threshold of 2.0 inches and greater

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue
Table 6 155

625 73.24 136 9,960 726421 1.466 .929 .071 121.46 82 9,960 440936 1.251 .895 .105

626 63.69 170 10,827 888638 -.777 .219 .219 130.45 83 10,827 452714 .119 .547 .453

627 492.54 24 11,821 130297 -.691 .245 .245 1182.10 10 11,821 65350 .579 .719 .281

628 555.89 9 5,003 17400 -1.180 .119 .119 1667.67 3 5,003 2808 -1.878 .030 .030

629 91.85 288 26,452 3824250 .117 .547 .453 164.30 161 26,452 2191702 .643 .740 .260

630 79.38 125 9,923 631030 .339 .633 .367 141.76 70 9,923 333133 -.591 .277 .277

631 83.16 131 10,894 729641 .447 .672 .328 162.60 67 10,894 368927 .155 .561 .439

632 70.44 113 7,960 467633 .733 .768 .232 139.65 57 7,960 252643 1.486 .931 .069

633 63.04 27 1,702 23556 .227 .590 .410 141.83 12 1,702 9390 -.483 .315 .315

634 290.00 1 290 150 .060 .524 .476 -- -- -- -- -- -- --

635 80.85 332 26,842 4673067 1.539 .938 .062 133.54 201 26,842 2810705 1.029 .848 .152

636 39.06 531 20,742 5736844 1.666 .952 .048 67.34 308 20,742 3226372 .306 .620 .380

637 143.59 170 24,410 2166865 1.002 .842 .158 317.01 77 24,410 1022631 1.340 .910 .090

638 129.24 86 11,115 518344 1.358 .913 .087 277.88 40 11,115 237098 .729 .767 .233

639 87.07 60 5,224 157008 .025 .510 .490 163.25 32 5,224 84264 .080 .532 .468

640 34.30 171 5,865 544065 1.925 .973 .027 56.39 104 5,865 321306 .946 .828 .172

641 170.86 7 1,196 4470 .311 .622 .378 398.67 3 1,196 2184 .652 .743 .257

642 -- -- -- -- -- -- -- -- -- -- -- -- -- --

643 58.56 561 32,853 9314895 .444 .671 .329 107.36 306 32,853 5238906 1.280 .900 .100

644 117.76 21 2,473 29578 1.104 .865 .135 247.30 10 2,473 13921 .689 .755 .245

645 117.27 234 27,442 3312271 .838 .799 .201 194.62 141 27,442 1905208 -.313 .377 .377

646 828.60 25 20,715 291263 1.081 .860 .140 3452.50 6 20,715 68275 .419 .662 .338

647 75.58 12 907 6738 1.429 .923 .077 113.38 8 907 4486 1.159 .877 .123

648 57.97 33 1,913 34900 1.051 .853 .147 119.56 16 1,913 16692 .628 .735 .265

649 510.63 16 8,170 42421 -2.432 .008 .008 2042.50 4 8,170 10834 -1.167 .122 .122

650 99.25 145 14,391 1077660 .686 .754 .246 208.57 69 14,391 502732 .181 .572 .428

651 254.73 11 2,802 17372 .731 .768 .232 560.40 5 2,802 9361 1.303 .904 .096

652 99.75 8 798 3092 -.154 .439 .439 199.50 4 798 1853 .558 .711 .289

653 77.36 14 1,083 7120 -.394 .347 .347 120.33 9 1,083 4195 -.723 .235 .235

654 152.22 68 10,351 397091 1.833 .967 .033 333.90 31 10,351 185104 1.483 .931 .069

655 79.47 36 2,861 47427 -.822 .206 .206 178.81 16 2,861 18443 -1.346 .089 .089

656 43.92 108 4,743 253451 -.188 .426 .426 84.70 56 4,743 127565 -.511 .305 .305

657 124.68 93 11,595 551703 .388 .651 .349 241.56 48 11,595 297840 .844 .800 .200

658 98.78 58 5,729 160227 -.470 .319 .319 184.81 31 5,729 79238 -1.038 .150 .150

659 81.65 34 2,776 45173 -.432 .333 .333 173.50 16 2,776 21354 -.266 .395 .395

660 57.89 83 4,805 200992 .125 .550 .450 94.22 51 4,805 125723 .323 .627 .373

661 51.49 55 2,832 75271 -.430 .334 .334 83.29 34 2,832 48034 -.023 .491 .491

662 78.43 70 5,490 209983 1.345 .911 .089 171.56 32 5,490 90847 .335 .631 .369

663 183.27 178 32,622 3034039 1.040 .851 .149 418.23 78 32,622 1263437 -.106 .458 .458

664 90.23 411 37,084 7476123 -.667 .253 .253 188.24 197 37,084 3565217 -.583 .280 .280

665 206.88 91 18,826 872066 .299 .617 .383 470.65 40 18,826 337707 -1.129 .129 .129

666 324.75 4 1,299 2591 -.009 .496 .496 433.00 3 1,299 2362 .637 .738 .262

667 113.13 121 13,689 754033 -1.706 .044 .044 220.79 62 13,689 348840 -2.427 .008 .008

668 172.47 45 7,761 151455 -1.542 .062 .062 298.50 26 7,761 81805 -1.671 .047 .047

669 67.57 84 5,676 241379 0.199 .579 .421 172.00 33 5,676 103026 0.996 .840 .160

670 132.58 64 8,485 259813 -.597 .275 .275 249.56 34 8,485 135608 -.605 .273 .273

671 61.03 308 18,797 3134779 2.521 .994 .006 114.62 164 18,797 1658790 1.690 .954 .046

672 113.79 170 19,344 1666502 .306 .620 .380 233.06 83 19,344 788638 -.278 .391 .391

Table 6. Summary of interoccurrence intervals for daily precipitation thresholds of 1.5 and 2.0 inches—Continued

Seq.

no.

Daily precipitation threshold of 1.5 inches and greater Daily precipitation threshold of 2.0 inches and greater

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue
156 Atlas of Interoccurrence Intervals for Selected Thresholds of Daily Precipitation in Texas 

673 119.15 46 5,481 127088 .096 .538 .462 249.14 22 5,481 61519 .166 .566 .434

674 74.50 24 1,788 19765 -.669 .252 .252 111.75 16 1,788 13526 -.377 .353 .353

675 85.45 31 2,649 38215 -.668 .252 .252 139.42 19 2,649 22912 -.676 .250 .250

676 63.92 52 3,324 77514 -1.288 .099 .099 138.50 24 3,324 32933 -1.480 .070 .070

677 190.23 108 20,545 1116512 .115 .546 .454 321.02 64 20,545 731139 1.553 .940 .060

678 157.00 1 157 51 -.607 .272 .272 -- -- -- -- -- -- --

679 202.05 112 22,630 1107434 -2.312 .010 .010 411.46 55 22,630 557542 -1.337 .091 .091

680 75.17 58 4,360 134624 .854 .803 .197 145.33 30 4,360 68243 .412 .660 .340

681 52.38 16 838 6065 -.660 .255 .255 93.11 9 838 3116 -.903 .183 .183

682 89.33 57 5,092 144870 -.023 .491 .491 181.86 28 5,092 64208 -.910 .181 .181

683 60.09 203 12,199 1273135 .696 .757 .243 115.09 106 12,199 668884 .616 .731 .269

684 67.78 229 15,522 1864105 1.281 .900 .100 136.16 114 15,522 884905 .003 .501 .499

685 39.98 881 35,218 15843391 1.093 .863 .137 66.45 530 35,218 9584355 1.075 .859 .141

686 88.59 66 5,847 230424 2.733 .997 .003 167.06 35 5,847 112615 1.031 .849 .151

687 73.71 21 1,548 14516 -.849 .198 .198 309.60 5 1,548 4108 .238 .594 .406

688 46.74 96 4,487 215636 .021 .508 .492 77.36 58 4,487 128301 -.185 .427 .427

689 67.03 88 5,899 279037 1.220 .889 .111 111.30 53 5,899 166004 .781 .783 .218

690 49.71 252 12,527 1591511 .228 .590 .410 92.11 136 12,527 849535 -.055 .478 .478

691 43.00 426 18,319 4250130 3.190 .999 .001 76.65 239 18,319 2309268 1.470 .929 .071

692 73.98 254 18,792 2749215 4.194 1.000 0 147.97 127 18,792 1401842 3.411 1.000 0

693 158.37 121 19,163 1229790 1.157 .876 .124 407.72 47 19,163 463399 .345 .635 .365

694 66.98 109 7,301 384560 -.607 .272 .272 135.20 54 7,301 174130 -1.485 .069 .069

695 201.96 67 13,531 441384 -.372 .355 .355 563.79 24 13,531 178693 .853 .803 .197

696 194.27 66 12,822 370823 -1.739 .041 .041 457.93 28 12,822 128974 -2.580 .005 .005

697 47.08 501 23,585 6077525 1.112 .867 .133 88.00 268 23,585 3301155 1.263 .897 .103

698 104.53 359 37,526 6867341 .640 .739 .261 207.33 181 37,526 3279140 -.803 .211 .211

699 93.12 17 1,583 13505 .026 .511 .489 175.89 9 1,583 7610 .355 .639 .361

700 70.98 277 19,662 2821583 1.042 .851 .149 125.24 157 19,662 1502617 -.574 .283 .283

701 61.83 29 1,793 27253 .450 .674 .326 94.37 19 1,793 19174 .949 .829 .171

702 134.67 9 1,212 4472 -.936 .175 .175 242.40 5 1,212 2052 -1.250 .106 .106

703 71.55 66 4,722 174448 1.682 .954 .046 131.17 36 4,722 100280 1.869 .969 .031

704 141.33 3 424 381 -1.203 .115 .115 424.00 1 424 24 -1.536 .062 .062

705 59.74 215 12,843 1449848 1.273 .899 .101 112.66 114 12,843 791284 1.496 .933 .067

706 49.63 723 35,879 13672157 2.520 .994 .006 101.07 355 35,879 6759781 2.005 .978 .022

707 41.19 226 9,308 1169208 2.907 .998 .002 87.81 106 9,308 530592 1.347 .911 .089

708 183.67 88 16,163 764712 1.223 .889 .111 384.83 42 16,163 348974 .316 .624 .376

709 -- -- -- -- -- -- -- -- -- -- -- -- -- --

710 149.75 8 1,198 3193 -1.635 .051 .051 199.67 6 1,198 2460 -1.339 .090 .090

711 134.73 110 14,820 878173 1.406 .920 .080 269.46 55 14,820 454662 1.485 .931 .069

712 89.40 15 1,341 8369 -1.126 .130 .130 268.20 5 1,341 2226 -1.301 .097 .097

713 57.69 176 10,153 938271 1.152 .875 .125 125.35 81 10,153 433268 .837 .799 .201

714 365.00 1 365 17 -1.571 .058 .058 -- -- -- -- -- -- --

715 146.00 10 1,460 7551 .188 .575 .425 730.00 2 1,460 1412 -.081 .468 .468

716 263.17 24 6,316 78646 .320 .625 .375 574.18 11 6,316 41358 1.095 .863 .137

717 211.11 157 33,144 2523987 -0.649 .258 .258 466.82 71 33,144 1109051 -0.838 0.201 .201

718 38.46 179 6,885 580798 -1.332 .092 .092 79.14 87 6,885 292995 -.351 .363 .363

719 38.62 113 4,364 244036 -.189 .425 .425 68.19 64 4,364 135068 -.454 .325 .325

720 49.08 677 33,230 10770761 -1.914 .028 .028 92.31 360 33,230 5694619 -1.576 .058 .058

Table 6. Summary of interoccurrence intervals for daily precipitation thresholds of 1.5 and 2.0 inches—Continued

Seq.

no.

Daily precipitation threshold of 1.5 inches and greater Daily precipitation threshold of 2.0 inches and greater

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue
Table 6 157

721 74.40 490 36,455 8784663 -.630 .264 .264 135.52 269 36,455 4972061 .399 .655 .345

722 73.36 22 1,614 17058 -.319 .375 .375 134.50 12 1,614 8561 -.696 .243 .243

723 35.19 64 2,252 79111 1.355 .912 .088 56.30 40 2,252 49468 1.077 .859 .141

724 90.60 101 9,151 478078 .601 .726 .274 166.38 55 9,151 256813 .263 .604 .396

725 91.62 100 9,162 450745 -.278 .390 .390 190.88 48 9,162 225725 .319 .625 .375

726 77.67 15 1,165 7842 -.688 .246 .246 116.50 10 1,165 5417 -.384 .351 .351

727 50.77 498 25,281 6213964 -.497 .309 .309 96.13 263 25,281 3163833 -1.357 .087 .087

728 44.04 234 10,305 1328494 2.699 .997 .003 82.44 125 10,305 701150 1.716 .957 .043

729 64.53 100 6,453 340622 .965 .833 .167 115.23 56 6,453 201737 1.510 .935 .066

730 -- -- -- -- -- -- -- -- -- -- -- -- -- --

731 62.52 100 6,252 286853 -1.427 .077 .077 109.68 57 6,252 162232 -1.171 .121 .121

732 119.63 57 6,819 200724 .430 .666 .334 235.14 29 6,819 108631 .920 .821 .179

733 344.00 1 344 307 1.360 .913 .087 -- -- -- -- -- -- --

734 311.58 74 23,057 886033 .575 .717 .283 922.28 25 23,057 286857 -.041 .484 .484

735 197.90 10 1,979 8769 -.623 .267 .267 659.67 3 1,979 4269 1.314 .906 .094

736 103.80 78 8,096 334065 .888 .813 .187 238.12 34 8,096 171691 2.499 .994 .006

737 1323.50 2 2,647 3632 .912 .819 .181 2647.00 1 2,647 2018 .909 .818 .182

738 325.75 44 14,333 322063 .246 .597 .403 955.53 15 14,333 136573 1.814 .965 .035

739 383.62 13 4,987 29935 -.478 .316 .316 1662.33 3 4,987 4988 -1.000 .159 .159

740 -- -- -- -- -- -- -- -- -- -- -- -- -- --

741 142.00 1 142 33 -.927 .177 .177 -- -- -- -- -- -- --

742 65.19 406 26,466 5471680 .644 .740 .260 117.11 226 26,466 3065312 .650 .742 .258

743 47.24 707 33,395 12543690 2.881 .998 .002 92.76 360 33,395 6245793 1.283 .900 .100

744 126.66 50 6,333 146779 -.893 .186 .186 226.18 28 6,333 75037 -1.408 .080 .080

745 78.54 114 8,954 541905 1.142 .873 .127 172.19 52 8,954 266313 1.798 .964 .036

746 100.75 204 20,552 2184463 1.040 .851 .149 228.36 90 20,552 1000908 1.352 .912 .088

747 147.14 133 19,569 1342364 .630 .736 .265 305.77 64 19,569 664013 .837 .798 .202

748 49.03 672 32,946 10484068 -2.376 .009 .009 79.39 415 32,946 6314049 -2.696 .004 .004

749 71.44 190 13,573 1129738 -2.957 .002 .002 122.28 111 13,573 626590 -3.070 .001 .001

750 43.61 426 18,579 4351067 3.557 1.000 0 84.07 221 18,579 2338096 3.576 1.000 0

751 56.09 136 7,628 517121 -.062 .475 .475 97.80 78 7,628 272603 -1.280 .100 .100

752 608.00 2 1,216 1498 .568 .715 .285 -- -- -- -- -- -- --

753 67.77 30 2,033 35264 1.484 .931 .069 184.82 11 2,033 13473 1.177 .880 .120

754 47.69 54 2,575 65859 -.671 .251 .251 85.83 30 2,575 32470 -1.512 .065 .065

755 123.56 174 21,499 1786737 -1.022 .153 .153 223.95 96 21,499 1000530 -.517 .303 .303

756 -- -- -- -- -- -- -- -- -- -- -- -- -- --

757 135.91 43 5,844 132012 .576 .717 .283 365.25 16 5,844 56557 1.453 .927 .073

758 57.55 562 32,344 9222459 .605 .727 .273 100.45 322 32,344 5219309 .071 .528 .472

759 112.35 137 15,392 1149207 1.824 .966 .034 236.80 65 15,392 541140 1.142 .873 .127

760 124.10 172 21,345 1968656 1.646 .950 .050 215.61 99 21,345 1100753 .721 .764 .236

761 119.74 113 13,531 698511 -1.589 .056 .056 198.99 68 13,531 430944 -.904 .183 .183

762 258.07 98 25,291 1202722 -.506 .307 .307 683.54 37 25,291 465646 -.050 .480 .480

763 84.57 14 1,184 8591 .237 .594 .406 98.67 12 1,184 7293 .160 .563 .437

764 68.30 480 32,783 7751277 -.563 .287 .287 142.54 230 32,783 3645865 -.865 .194 .194

765 62.22 196 12,195 1202791 0.156 .562 .438 110.86 110 12,195 719558 1.323 .907 .093

766 74.28 36 2,674 40683 -1.608 .054 .054 116.26 23 2,674 25063 -1.537 .062 .062

767 134.97 246 33,202 4013892 -.465 .321 .321 313.23 106 33,202 1949854 1.927 .973 .027

768 117.80 288 33,925 4862636 -.136 .446 .446 224.67 151 33,925 2412530 -1.237 .108 .108

Table 6. Summary of interoccurrence intervals for daily precipitation thresholds of 1.5 and 2.0 inches—Continued

Seq.

no.

Daily precipitation threshold of 1.5 inches and greater Daily precipitation threshold of 2.0 inches and greater

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue
158 Atlas of Interoccurrence Intervals for Selected Thresholds of Daily Precipitation in Texas 

769 105.90 20 2,118 24050 1.050 .853 .147 192.55 11 2,118 13299 .814 .792 .208

770 406.80 20 8,136 103060 2.066 .981 .019 625.85 13 8,136 64272 1.345 .911 .089

771 206.33 18 3,714 38179 1.045 .852 .148 619.00 6 3,714 11618 .181 .572 .428

772 61.00 3 183 333 .639 .739 .261 61.00 3 183 333 .639 .739 .261

773 86.17 6 517 1641 .246 .597 .403 129.25 4 517 852 -.610 .271 .271

774 100.55 307 30,870 4862391 .793 .786 .214 179.48 172 30,870 2751020 .823 .795 .205

775 76.00 4 304 669 .348 .636 .364 152.00 2 304 390 .693 .756 .244

776 65.56 107 7,015 397786 1.073 .858 .142 134.90 52 7,015 200556 1.244 .893 .107

777 60.11 114 6,852 404820 .675 .750 .250 116.14 59 6,852 211631 .625 .734 .266

778 295.42 33 9,749 129201 -1.958 .025 .025 609.31 16 9,749 50747 -2.420 .008 .008

779 132.29 121 16,007 1113508 2.854 .998 .002 275.98 58 16,007 498902 .986 .838 .162

780 59.48 581 34,558 10395427 1.482 .931 .069 111.48 310 34,558 5525010 .959 .831 .169

781 151.82 228 34,614 4001617 .369 .644 .356 323.50 107 34,614 1900104 .467 .680 .320

782 38.60 241 9,303 1190907 1.677 .953 .047 69.95 133 9,303 666436 1.543 .939 .061

783 162.22 9 1,460 7228 .520 .699 .301 365.00 4 1,460 3288 .437 .669 .331

784 196.71 24 4,721 52436 -.632 .264 .264 472.10 10 4,721 24329 .168 .567 .433

785 244.60 78 19,079 795829 1.064 .856 .144 545.11 35 19,079 310784 -.709 .239 .239

786 267.69 73 19,541 719600 .132 .552 .448 610.66 32 19,541 356893 1.386 .917 .083

787 62.42 97 6,055 272415 -1.235 .109 .109 85.28 71 6,055 197962 -1.154 .124 .124

788 47.41 34 1,612 28819 .522 .699 .301 100.75 16 1,612 13121 .121 .548 .452

789 50.27 166 8,344 680283 -.395 .346 .346 93.75 89 8,344 390822 .859 .805 .195

790 40.35 55 2,219 65613 .966 .833 .167 76.52 29 2,219 31771 -.117 .453 .453

791 73.66 64 4,714 168235 1.597 .945 .055 124.05 38 4,714 103544 1.666 .952 .048

792 64.29 7 450 1842 .777 .781 .219 75.00 6 450 1514 .515 .697 .303

793 49.44 388 19,181 3692616 -.261 .397 .397 104.25 184 19,181 1774690 .134 .553 .447

794 51.93 225 11,685 1367067 1.038 .850 .150 108.19 108 11,685 648468 .499 .691 .309

795 84.39 202 17,047 1895726 2.488 .994 .006 168.78 101 17,047 942311 1.647 .950 .050

796 168.55 31 5,225 82412 .170 .567 .433 307.35 17 5,225 37858 -1.054 .146 .146

797 127.05 224 28,459 3317838 1.061 .856 .144 210.81 135 28,459 2039020 1.237 .892 .108

798 115.67 6 694 1973 -.222 .412 .412 694.00 1 694 486 .694 .756 .244

799 130.79 70 9,155 307449 -.587 .279 .279 416.14 22 9,155 79744 -1.691 .045 .045

800 229.60 5 1,148 3488 .834 .798 .202 1148.00 1 1,148 1038 1.400 .919 .081

801 250.92 59 14,804 462808 .795 .787 .213 779.16 19 14,804 147994 .395 .654 .346

802 302.40 5 1,512 2675 -1.132 .129 .129 504.00 3 1,512 1238 -1.362 .087 .087

803 72.99 100 7,299 362071 -.137 .446 .446 165.89 44 7,299 162523 .139 .555 .445

804 136.20 5 681 673 -2.342 .010 .010 340.50 2 681 224 -1.644 .050 .050

805 102.62 112 11,493 649993 .182 .572 .428 191.55 60 11,493 298240 -1.811 .035 .035

806 49.60 346 17,161 3072696 1.127 .870 .130 104.01 165 17,161 1442881 .426 .665 .335

807 67.69 194 13,131 1365634 1.741 .959 .041 139.69 94 13,131 638737 .587 .721 .279

808 78.31 230 18,012 2059922 -.145 .442 .442 159.40 113 18,012 1057366 .718 .764 .236

809 196.19 94 18,442 809784 -1.104 .135 .135 409.82 45 18,442 423840 .249 .598 .402

810 201.63 102 20,566 1053792 .082 .533 .467 373.93 55 20,566 526880 -.879 .190 .190

811 48.53 152 7,376 593009 1.236 .892 .108 83.82 88 7,376 324754 .011 .504 .496

812 113.29 59 6,684 221678 1.653 .951 .049 257.08 26 6,684 109515 2.299 .989 .011

813 20.75 4 83 207 0.856 .804 .196 83.00 1 83 66 1.023 .847 .153

814 287.11 85 24,404 1072648 .546 .707 .293 677.89 36 24,404 459049 .468 .680 .320

815 47.10 645 30,377 10416012 2.781 .997 .003 98.95 307 30,377 5094391 2.809 .998 .002

816 47.86 270 12,922 1918599 2.841 .998 .002 91.65 141 12,922 1050139 3.141 .999 .001

Table 6. Summary of interoccurrence intervals for daily precipitation thresholds of 1.5 and 2.0 inches—Continued

Seq.

no.

Daily precipitation threshold of 1.5 inches and greater Daily precipitation threshold of 2.0 inches and greater

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue
Table 6 159

817 76.79 81 6,220 235949 -.988 .162 .162 163.68 38 6,220 111713 -.584 .280 .280

818 69.59 285 19,833 2953122 1.313 .905 .095 135.84 146 19,833 1541242 1.351 .912 .088

819 246.68 117 28,862 1630463 -.643 .260 .260 627.44 46 28,862 630103 -.597 .275 .275

820 99.00 9 891 5452 1.869 .969 .031 148.50 6 891 3650 1.551 .940 .061

821 215.16 37 7,961 143382 -.279 .390 .390 468.29 17 7,961 62702 -.524 .300 .300

822 100.26 190 19,050 1849253 .521 .699 .301 216.48 88 19,050 909179 1.376 .916 .084

823 122.33 266 32,540 4338506 .070 .528 .472 225.97 144 32,540 2435791 .824 .795 .205

824 117.89 18 2,122 17527 -.605 .273 .273 303.14 7 2,122 6916 -.315 .376 .376

825 96.31 42 4,045 91746 .899 .816 .184 161.80 25 4,045 49918 -.110 .456 .456

826 48.10 551 26,503 7310775 .051 .520 .480 95.34 278 26,503 3716231 .253 .600 .400

827 48.10 217 10,437 1196663 1.448 .926 .074 89.21 117 10,437 664882 1.667 .952 .048

828 49.19 525 25,827 7088266 1.807 .965 .035 92.57 279 25,827 3614313 .092 .537 .463

829 37.51 144 5,401 386685 -.117 .453 .453 62.08 87 5,401 219391 -1.069 .143 .143

830 79.89 164 13,102 1105045 .633 .737 .263 140.88 93 13,102 620843 .318 .625 .375

831 65.94 215 14,176 1617842 1.565 .941 .059 119.13 119 14,176 939363 2.148 .984 .016

832 97.33 18 1,752 13966 -.840 .201 .201 159.27 11 1,752 8459 -.702 .242 .242

833 126.23 13 1,641 9830 -.490 .312 .312 410.25 4 1,641 1999 -1.354 .088 .088

834 164.24 25 4,106 57622 1.063 .856 .144 342.17 12 4,106 32997 2.036 .979 .021

835 40.86 454 18,549 4368436 1.383 .917 .083 70.00 265 18,549 2568675 1.273 .898 .102

836 95.54 79 7,548 315975 .921 .821 .179 132.42 57 7,548 223588 .515 .697 .303

837 42.20 283 11,942 1835641 2.515 .994 .006 76.06 157 11,942 984319 1.085 .861 .139

838 37.53 203 7,618 814192 1.307 .904 .096 69.89 109 7,618 444034 1.257 .896 .104

839 53.62 42 2,252 47150 -.034 .487 .487 102.36 22 2,252 22026 -.901 .184 .184

840 74.71 488 36,458 9590737 2.989 .999 .001 128.83 283 36,458 5503945 1.949 .974 .026

841 41.27 438 18,077 4281776 2.957 .998 .002 76.27 237 18,077 2386210 3.038 .999 .001

842 49.16 381 18,731 3780686 2.013 .978 .022 92.27 203 18,731 2061177 2.077 .981 .019

843 40.38 89 3,594 174573 1.496 .933 .067 102.69 35 3,594 71715 1.437 .925 .075

844 79.43 221 17,555 1913206 -.353 .362 .362 156.74 112 17,555 906360 -1.431 .076 .076

845 41.10 91 3,740 188858 1.815 .965 .035 69.26 54 3,740 115252 1.799 .964 .036

846 33.22 195 6,477 639047 .289 .614 .386 64.13 101 6,477 332835 .306 .620 .380

847 66.18 271 17,934 2332124 -1.149 .125 .125 129.02 139 17,934 1114146 -2.167 .015 .015

848 76.91 374 28,763 5762070 2.388 .992 .008 139.63 206 28,763 3297190 2.808 .998 .002

849 53.01 128 6,785 441696 .337 .632 .368 84.81 80 6,785 291297 1.136 .872 .128

850 159.00 9 1,431 6819 .306 .620 .380 477.00 3 1,431 2773 .876 .809 .191

851 91.25 4 365 1128 1.889 .971 .029 182.50 2 365 448 .557 .711 .289

852 45.70 10 457 2732 1.072 .858 .142 76.17 6 457 1459 .272 .607 .393

853 91.33 3 274 260 -1.102 .135 .135 137.00 2 274 156 -1.055 .146 .146

854 143.17 132 18,899 1312350 1.037 .850 .150 299.98 63 18,899 665388 1.618 .947 .053

855 62.58 89 5,570 272820 1.645 .950 .050 121.09 46 5,570 135231 .653 .743 .257

856 194.89 96 18,709 923491 .481 .685 .315 479.72 39 18,709 354343 -.311 .378 .378

857 100.00 91 9,100 436563 .898 .815 .185 206.82 44 9,100 222673 1.290 .901 .099

858 127.47 83 10,580 502101 2.265 .988 .012 293.89 36 10,580 204660 .776 .781 .219

859 130.10 72 9,367 343926 .293 .615 .385 323.00 29 9,367 136557 .051 .520 .480

860 304.25 4 1,217 2776 .487 .687 .313 1217.00 1 1,217 1177 1.618 .947 .053

861 111.12 130 14,445 891977 -0.988 .162 .162 225.70 64 14,445 382230 -2.398 .008 .008

862 48.61 157 7,632 596983 -.077 .469 .469 88.74 86 7,632 316044 -.594 .276 .276

863 71.00 6 426 1337 .196 .578 .422 213.00 2 426 579 .880 .810 .190

864 269.69 67 18,069 633405 .658 .745 .255 645.32 28 18,069 264812 .429 .666 .334

Table 6. Summary of interoccurrence intervals for daily precipitation thresholds of 1.5 and 2.0 inches—Continued

Seq.

no.

Daily precipitation threshold of 1.5 inches and greater Daily precipitation threshold of 2.0 inches and greater

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue
160 Atlas of Interoccurrence Intervals for Selected Thresholds of Daily Precipitation in Texas 

865 156.13 15 2,342 15976 -.607 .272 .272 390.33 6 2,342 6119 -.548 .292 .292

866 209.31 13 2,721 17132 -.196 .422 .422 340.13 8 2,721 8469 -1.087 .139 .139

867 89.83 177 15,899 1504875 1.602 .945 .055 160.60 99 15,899 886763 2.185 .986 .014

868 98.85 220 21,746 2515283 1.323 .907 .093 178.25 122 21,746 1398843 1.043 .852 .148

869 200.44 92 18,440 830606 -.345 .365 .365 439.05 42 18,440 348126 -1.134 .128 .128

870 43.75 36 1,575 31028 .982 .837 .163 105.00 15 1,575 14059 1.276 .899 .101

871 -- -- -- -- -- -- -- -- -- -- -- -- -- --

872 81.00 6 486 1100 -1.042 .149 .149 486.00 1 486 36 -1.476 .070 .070

873 34.77 675 23,470 8050994 .738 .770 .230 57.38 409 23,470 4805740 .045 .518 .482

874 29.97 191 5,724 548147 .066 .526 .474 47.70 120 5,724 350745 .404 .657 .343

875 44.09 11 485 2708 .087 .535 .465 97.00 5 485 1349 .436 .669 .331

876 -- -- -- -- -- -- -- -- -- -- -- -- -- --

877 143.33 3 430 861 1.005 .842 .158 430.00 1 430 237 .177 .570 .430

878 48.65 322 15,666 2474150 -.592 .277 .277 97.30 161 15,666 1191248 -1.218 .112 .112

879 139.05 133 18,493 1222741 -.114 .454 .454 271.96 68 18,493 640897 .276 .609 .391

880 -- -- -- -- -- -- -- -- -- -- -- -- -- --

881 135.73 137 18,595 1343072 1.103 .865 .135 261.90 71 18,595 700790 .899 .816 .184

882 79.39 23 1,826 17828 -1.254 .105 .105 228.25 8 1,826 7702 .267 .605 .395

883 109.01 100 10,901 553167 .258 .602 .398 259.55 42 10,901 220358 -.420 .337 .337

884 148.16 92 13,631 626617 -.011 .496 .496 309.80 44 13,631 305369 .210 .583 .417

885 121.71 244 29,698 3922393 2.235 .987 .013 247.48 120 29,698 1938265 1.665 .952 .048

886 48.78 438 21,366 4816798 1.066 .857 .143 80.63 265 21,366 2997938 1.663 .952 .048

887 56.36 445 25,079 6019512 2.877 .998 .002 115.04 218 25,079 2978791 2.294 .989 .011

888 78.87 240 18,929 2403373 1.558 .940 .060 153.89 123 18,929 1254593 1.493 .932 .068

889 165.37 83 13,726 636979 1.866 .969 .031 415.94 33 13,726 254610 1.236 .892 .108

890 172.17 76 13,085 455008 -1.282 .100 .100 436.17 30 13,085 201836 .269 .606 .394

891 151.19 120 18,143 1063785 -.432 .333 .333 266.81 68 18,143 636593 .457 .676 .324

892 129.04 56 7,226 200242 -.134 .447 .447 225.81 32 7,226 121530 .501 .692 .308

893 159.40 169 26,939 2034365 -2.394 .008 .008 324.57 83 26,939 997351 -1.703 .044 .044

894 89.38 63 5,631 173772 -.279 .390 .390 187.70 30 5,631 80546 -.440 .330 .330

895 397.00 43 17,071 414046 1.455 .927 .073 1004.18 17 17,071 184787 1.953 .975 .025

896 50.86 703 35,755 13131934 2.061 .980 .020 92.87 385 35,755 7393520 2.522 .994 .006

897 61.33 3 184 379 1.120 .869 .132 92.00 2 184 323 1.850 .968 .032

898 34.60 35 1,211 24532 1.615 .947 .053 67.28 18 1,211 14155 2.195 .986 .014

899 58.00 1 58 20 -.538 .296 .296 58.00 1 58 20 -.538 .296 .296

900 66.57 23 1,531 15153 -1.158 .124 .124 127.58 12 1,531 10345 .757 .775 .225

901 100.15 340 34,050 6177297 2.145 .984 .016 183.07 186 34,050 3337238 1.273 .898 .102

902 93.67 12 1,124 7316 .509 .695 .305 187.33 6 1,124 2393 -1.232 .109 .109

903 459.56 55 25,276 795453 1.855 .968 .032 1011.04 25 25,276 362446 1.275 .899 .101

904 -- -- -- -- -- -- -- -- -- -- -- -- -- --

905 302.29 55 16,626 476401 .539 .705 .295 722.87 23 16,626 219952 1.249 .894 .106

906 169.15 187 31,631 2913617 -.351 .363 .363 385.74 82 31,631 1318690 .264 .604 .396

907 -- -- -- -- -- -- -- -- -- -- -- -- -- --

908 195.86 101 19,782 1068168 1.205 .886 .114 460.05 43 19,782 420467 -.129 .448 .448

909 182.44 46 8,392 218950 1.578 .943 .057 466.22 18 8,392 92697 1.671 .953 .047

910 1012.14 7 7,085 29373 .846 .801 .199 2361.67 3 7,085 9902 -.205 .419 .419

911 2097.00 1 2,097 698 -.579 .281 .281 -- -- -- -- -- -- --

912 37.75 8 302 1092 -.470 .319 .319 75.50 4 302 590 -.080 .468 .468

Table 6. Summary of interoccurrence intervals for daily precipitation thresholds of 1.5 and 2.0 inches—Continued

Seq.

no.

Daily precipitation threshold of 1.5 inches and greater Daily precipitation threshold of 2.0 inches and greater

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue
Table 6 161

913 80.28 80 6,422 294049 2.242 .988 .012 133.79 48 6,422 180045 2.018 .978 .022

914 78.74 46 3,622 89572 .884 .811 .189 190.63 19 3,622 34582 .038 .515 .485

915 52.17 645 33,649 11457251 2.454 .993 .007 96.97 347 33,649 6278364 2.433 .993 .007

916 52.85 362 19,131 3934158 4.487 1.000 0 101.76 188 19,131 2067897 3.560 1.000 0

917 256.97 30 7,709 93192 -1.841 .033 .033 513.93 15 7,709 40661 -1.991 .023 .023

918 37.21 238 8,856 1117683 1.618 .947 .053 68.12 130 8,856 618581 1.473 .930 .070

919 100.01 98 9,801 470645 -.343 .366 .366 227.93 43 9,801 225409 .792 .786 .214

920 49.24 388 19,104 3846467 1.292 .902 .098 93.65 204 19,104 2064758 1.475 .930 .070

921 85.65 51 4,368 132303 2.323 .990 .010 208.00 21 4,368 53539 1.328 .908 .092

922 187.97 121 22,744 1374733 -.018 .493 .493 406.14 56 22,744 626580 -.209 .417 .417

923 173.20 193 33,427 3123693 -.761 .223 .223 464.26 72 33,427 1085257 -1.443 .075 .075

924 639.00 1 639 399 .431 .667 .333 639.00 1 639 399 .431 .667 .333

925 300.36 14 4,205 36390 1.531 .937 .063 600.71 7 4,205 16886 .675 .750 .250

926 69.50 8 556 2953 1.606 .946 .054 111.20 5 556 1864 1.321 .907 .093

927 68.20 65 4,433 140194 -.376 .354 .354 105.55 42 4,433 88857 -.511 .305 .305

928 195.46 39 7,623 157177 .621 .733 .267 476.44 16 7,623 62705 .196 .578 .422

929 48.66 323 15,716 2483045 -.676 .250 .250 75.56 208 15,716 1594695 -.608 .272 .272

930 162.64 56 9,108 276150 1.074 .858 .142 350.31 26 9,108 128193 .730 .767 .233

931 105.28 46 4,843 131644 2.136 .984 .016 193.72 25 4,843 85385 3.555 1.000 0

932 95.74 34 3,255 56135 .146 .558 .442 203.44 16 3,255 27145 .294 .616 .384

933 -- -- -- -- -- -- -- -- -- -- -- -- -- --

934 62.33 89 5,547 255617 .581 .719 .281 95.64 58 5,547 168448 .622 .733 .267

935 37.66 523 19,694 5502216 2.709 .997 .003 66.09 298 19,694 3252145 3.238 .999 .001

936 35.62 267 9,510 1276702 .159 .563 .437 58.70 162 9,510 767861 -.070 .472 .472

937 37.48 238 8,920 1001195 -1.518 .065 .065 61.10 146 8,920 635068 -.517 .303 .303

938 94.09 269 25,311 3626810 1.857 .968 .032 164.36 154 25,311 2083847 1.488 .932 .068

939 54.28 398 21,605 4436266 1.100 .864 .136 89.65 241 21,605 2823056 2.269 .988 .012

940 98.14 162 15,898 1344085 .965 .833 .167 165.60 96 15,898 728394 -.772 .220 .220

941 62.08 265 16,452 2049099 -1.692 .045 .045 104.13 158 16,452 1219767 -1.339 .090 .090

942 116.20 113 13,131 720357 -.535 .296 .296 226.40 58 13,131 357573 -.805 .211 .211

943 151.14 216 32,647 3478218 -.344 .365 .365 302.29 108 32,647 1726998 -.367 .357 .357

944 52.66 109 5,740 311764 -.062 .475 .475 104.36 55 5,740 128469 -2.391 .008 .008

945 89.76 238 21,362 2525291 -.177 .430 .430 169.54 126 21,362 1366356 .297 .617 .383

946 58.45 168 9,820 849772 .678 .751 .249 116.91 84 9,820 468890 2.173 .985 .015

947 83.04 166 13,784 1255926 2.182 .985 .015 149.83 92 13,784 694569 1.585 .944 .056

948 135.11 9 1,216 6404 .885 .812 .188 608.00 2 1,216 1646 .866 .807 .193

949 646.56 41 26,509 631572 1.799 .964 .036 1767.27 15 26,509 216947 .612 .730 .270

950 -- -- -- -- -- -- -- -- -- -- -- -- -- --

951 52.79 235 12,405 1460535 .054 .521 .479 106.94 116 12,405 724486 .130 .552 .448

952 61.61 80 4,929 211349 1.115 .868 .133 140.83 35 4,929 103745 2.077 .981 .019

953 87.66 160 14,026 1118686 -.066 .474 .474 157.60 89 14,026 647887 .621 .733 .267

954 63.51 109 6,922 408170 1.482 .931 .069 115.37 60 6,922 218426 .696 .757 .243

955 109.09 303 33,055 5061479 .323 .627 .373 254.27 130 33,055 2066218 -.757 .225 .225

956 104.31 333 34,736 5605167 -.975 .165 .165 221.25 157 34,736 2792503 .523 .700 .300

957 49.80 86 4,283 177427 -0.588 .278 .278 79.32 54 4,283 111903 -0.411 .340 .340

958 169.50 74 12,543 460895 -.103 .459 .459 404.61 31 12,543 172127 -1.106 .135 .135

959 52.96 261 13,823 1716364 -1.358 .087 .087 99.45 139 13,823 966690 .127 .551 .449

960 43.39 18 781 8428 1.463 .928 .072 111.57 7 781 3558 1.382 .917 .083

Table 6. Summary of interoccurrence intervals for daily precipitation thresholds of 1.5 and 2.0 inches—Continued

Seq.

no.

Daily precipitation threshold of 1.5 inches and greater Daily precipitation threshold of 2.0 inches and greater

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue
162 Atlas of Interoccurrence Intervals for Selected Thresholds of Daily Precipitation in Texas 

961 81.34 247 20,090 2487625 .071 .529 .472 158.19 127 20,090 1308513 .502 .692 .308

962 719.00 1 719 320 -.190 .424 .424 -- -- -- -- -- -- --

963 126.78 9 1,141 4182 -.964 .168 .168 190.17 6 1,141 2771 -.808 .210 .210

964 100.75 20 2,015 20884 .282 .611 .389 201.50 10 2,015 10268 .105 .542 .458

965 99.94 102 10,194 475533 -1.493 .068 .068 208.04 49 10,194 219338 -1.477 .070 .070

966 240.24 37 8,889 171664 .462 .678 .322 444.45 20 8,889 88316 -.050 .480 .480

967 202.16 25 5,054 63001 -.024 .490 .490 722.00 7 5,054 16036 -.428 .334 .334

968 56.54 28 1,583 23050 .367 .643 .357 121.77 13 1,583 9389 -.547 .292 .292

969 71.59 17 1,217 12253 1.318 .906 .094 173.86 7 1,217 5263 1.080 .860 .140

970 92.23 355 32,743 6050733 1.341 .910 .090 170.54 192 32,743 3342256 1.519 .936 .064

971 57.40 30 1,722 26704 .321 .626 .374 107.63 16 1,722 13818 .021 .508 .492

972 84.98 218 18,526 2160333 1.786 .963 .037 187.13 99 18,526 942048 .470 .681 .319

973 325.68 60 19,541 599352 .300 .618 .382 630.36 31 19,541 331191 .901 .816 .184

974 67.64 165 11,161 922315 .037 .515 .485 139.51 80 11,161 436565 -.343 .366 .366

975 59.07 210 12,404 1264092 -.739 .230 .230 121.61 102 12,404 580818 -1.432 .076 .076

976 63.43 14 888 6814 .624 .733 .267 111.00 8 888 4575 1.411 .921 .079

977 -- -- -- -- -- -- -- -- -- -- -- -- -- --

978 59.88 223 13,354 1632530 2.494 .994 .006 103.52 129 13,354 970769 2.500 .994 .006

979 60.16 95 5,715 290180 1.164 .878 .122 112.06 51 5,715 162077 1.387 .917 .083

980 51.04 70 3,573 123631 -.165 .434 .434 87.15 41 3,573 72876 -.056 .478 .478

981 -- -- -- -- -- -- -- -- -- -- -- -- -- --

982 77.20 5 386 670 -1.184 .118 .118 128.67 3 386 585 .031 .512 .488

983 52.28 200 10,455 1092960 1.112 .867 .133 111.22 94 10,455 482489 -.304 .381 .381

984 90.62 39 3,534 69010 .015 .506 .494 271.85 13 3,534 23683 .194 .577 .423

985 80.80 15 1,212 7866 -.903 .183 .183 173.14 7 1,212 5180 1.013 .844 .156

986 86.63 40 3,465 88433 3.024 .999 .001 123.75 28 3,465 60211 2.211 .986 .014

987 93.64 240 22,473 2532442 -1.635 .051 .051 161.68 139 22,473 1468250 -1.224 .111 .111

988 65.17 36 2,346 49470 1.782 .963 .037 156.40 15 2,346 21240 1.390 .918 .082

989 47.67 339 16,159 2788752 .580 .719 .281 95.05 170 16,159 1428994 .912 .819 .181

990 55.97 333 18,639 3356862 2.582 .995 .005 109.00 171 18,639 1722772 1.835 .967 .033

991 86.39 215 18,574 2190643 2.467 .993 .007 182.10 102 18,574 1096633 2.758 .997 .003

992 49.36 405 19,989 4244976 1.698 .955 .045 100.45 199 19,989 2102553 1.396 .919 .081

993 152.11 9 1,369 5715 -.376 .354 .354 342.25 4 1,369 3138 .506 .694 .306

994 98.05 63 6,177 227113 2.299 .989 .011 199.26 31 6,177 112233 1.661 .952 .048

995 72.24 228 16,470 1893429 .221 .587 .413 143.22 115 16,470 956332 .183 .572 .428

996 131.74 219 28,850 3472742 2.545 .995 .005 216.92 133 28,850 2108687 1.980 .976 .024

997 75.91 363 27,555 5430150 2.830 .998 .002 135.74 203 27,555 3109454 2.758 .997 .003

998 87.75 243 21,324 2772917 1.897 .971 .029 148.08 144 21324 1630983 1.295 .902 .098

999 68.85 53 3,649 80355 -2.131 .017 .017 125.83 29 3,649 38958 -2.460 .007 .007

1000 54.59 165 9,008 760690 .525 .700 .300 100.09 90 9,008 422775 .706 .760 .240

1001 65.71 300 19,714 3187246 2.335 .990 .010 118.05 167 19,714 1821586 2.386 .991 .009

1002 -- -- -- -- -- -- -- -- -- -- -- -- -- --

1003 141.36 144 20,356 1536538 1.006 .843 .157 278.85 73 20,356 791763 .971 .834 .166

1004 69.33 294 20,384 2960151 -.360 .360 .360 122.80 166 20,384 1606779 -1.122 .131 .131

1005 111.76 191 21,346 1858496 -2.114 .017 .017 260.32 82 21,346 819299 -1.002 .158 .158

1006 57.76 49 2,830 57919 -1.996 .023 .023 113.20 25 2,830 29704 -1.388 .083 .083

1007 66.10 128 8,461 510275 -1.130 .129 .129 119.17 71 8,461 284670 -.763 .223 .223

1008 67.45 206 13,894 1363847 -1.168 .121 .121 115.78 120 13,894 825678 -.181 .428 .428

Table 6. Summary of interoccurrence intervals for daily precipitation thresholds of 1.5 and 2.0 inches—Continued

Seq.

no.

Daily precipitation threshold of 1.5 inches and greater Daily precipitation threshold of 2.0 inches and greater

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue
Table 6 163

1009 49.71 252 12,527 1531234 -.822 .206 .206 86.39 145 12,527 875090 -.761 .224 .224

1010 59.53 263 15,655 1961212 -1.329 .092 .092 101.00 155 15,655 1128494 -1.507 .066 .066

1011 105.72 193 20,404 2137592 2.061 .980 .020 175.90 116 20,404 1285622 1.611 .946 .054

1012 130.13 23 2,993 41098 1.612 .946 .054 299.30 10 2,993 15737 .283 .611 .389

1013 121.39 90 10,925 427310 -2.150 .016 .016 206.13 53 10,925 257946 -1.375 .085 .085

1014 63.30 37 2,342 43996 .163 .565 .435 123.26 19 2,342 22965 .243 .596 .404

1015 427.00 1 427 208 -.045 .482 .482 427.00 1 427 208 -.045 .482 .482

1016 58.59 342 20,037 3368155 -.544 .293 .293 103.82 193 20,037 1919615 -.174 .431 .431

1017 69.15 27 1,867 28961 1.341 .910 .090 124.47 15 1,867 14559 .267 .605 .395

1018 35.09 69 2,421 81191 -.402 .344 .344 71.21 34 2,421 36150 -1.229 .110 .110

1019 149.30 54 8,062 225279 .445 .672 .328 298.59 27 8,062 115545 .555 .710 .290

1020 147.20 40 5,888 128845 1.031 .849 .151 392.53 15 5,888 61599 2.649 .996 .004

1021 122.49 198 24,253 2450383 .501 .692 .308 247.48 98 24,253 1192801 .064 .525 .475

1022 54.86 180 9,875 890715 .051 .521 .479 101.80 97 9,875 503479 .874 .809 .191

1023 54.80 123 6,740 387020 -1.274 .101 .101 140.42 48 6,740 124305 -2.779 .003 .003

1024 63.39 185 11,727 1095860 .241 .595 .405 113.85 103 11,727 642501 1.122 .869 .131

1025 108.62 26 2,824 33535 -.764 .222 .222 256.73 11 2,824 18277 1.015 .845 .155

1026 63.71 300 19,114 2997039 1.360 .913 .087 141.59 135 19,114 1392144 1.590 .944 .056

1027 92.58 73 6,758 244241 -.146 .442 .442 160.91 42 6,758 137257 -.369 .356 .356

1028 128.51 213 27,372 3192877 2.409 .992 .008 248.84 110 27,372 1621715 1.403 .920 .080

1029 80.98 192 15,548 1536898 .712 .762 .238 153.94 101 15,548 846084 1.350 .912 .088

1030 68.03 180 12,246 1179896 1.639 .949 .051 122.46 100 12,246 703888 2.591 .995 .005

1031 253.80 10 2,538 12295 -.171 .432 .432 846.00 3 2,538 3633 -.137 .445 .445

1032 79.40 459 36,443 8562445 .882 .811 .189 148.75 245 36,443 4574738 .671 .749 .251

1033 43.30 495 21,434 5543561 1.734 .959 .042 90.06 238 21,434 2685782 1.416 .922 .078

1034 127.29 17 2,164 18099 -.115 .454 .454 240.44 9 2,164 10059 .171 .568 .432

1035 94.96 356 33,805 6040171 .124 .550 .450 185.74 182 33,805 2947364 -.979 .164 .164

1036 20.62 26 536 7314 .439 .669 .331 31.53 17 536 4631 .118 .547 .453

1037 38.73 11 426 1480 -2.116 .017 .017 60.86 7 426 876 -1.890 .029 .029

1038 68.06 51 3,471 85237 -.458 .324 .324 115.70 30 3,471 49104 -.540 .295 .295

1039 1750.50 4 7,002 23680 2.394 .992 .008 3501.00 2 7,002 13319 2.210 .986 .014

1040 528.54 13 6,871 50756 .852 .803 .197 1145.17 6 6,871 29947 1.921 .973 .027

1041 1166.67 3 3,500 6106 .489 .688 .312 3500.00 1 3,500 2269 .514 .696 .304

1042 32.84 378 12,414 2416697 1.011 .844 .156 64.32 193 12,414 1191552 -.129 .449 .449

1043 157.00 3 471 148 -2.372 .009 .009 -- -- -- -- -- -- --

1044 132.07 62 8,188 251891 -.104 .459 .459 292.43 28 8,188 111931 -.216 .414 .414

1045 176.98 113 19,999 1254300 2.026 .979 .021 363.62 55 19,999 568911 .442 .671 .329

1046 89.79 19 1,706 18873 1.242 .893 .107 121.86 14 1,706 14941 1.628 .948 .052

1047 84.57 239 20,211 2580551 1.833 .967 .033 144.36 140 20,211 1502649 1.273 .898 .102

1048 96.08 125 12,010 736790 -.357 .361 .361 190.64 63 12,010 373534 -.174 .431 .431

1049 73.09 67 4,897 163513 -.046 .481 .481 144.03 34 4,897 82007 -.151 .440 .440

1050 38.23 315 12,043 2033703 2.219 .987 .013 72.99 165 12,043 1066098 1.625 .948 .052

1051 85.89 208 17,865 1867861 .133 .553 .447 147.65 121 17,865 1074304 -.115 .454 .454

1052 80.44 9 724 2712 -.871 .192 .192 144.80 5 724 1286 -1.121 .131 .131

1053 31.64 33 1,044 17373 0.085 .534 .466 61.41 17 1,044 7576 -1.045 .148 .148

1054 61.00 1 61 21 -.540 .295 .295 -- -- -- -- -- -- --

1055 42.87 78 3,344 134190 .443 .671 .329 85.74 39 3,344 68115 .482 .685 .315

1056 140.13 15 2,102 17216 .617 .731 .269 191.09 11 2,102 11880 .159 .563 .437

Table 6. Summary of interoccurrence intervals for daily precipitation thresholds of 1.5 and 2.0 inches—Continued

Seq.

no.

Daily precipitation threshold of 1.5 inches and greater Daily precipitation threshold of 2.0 inches and greater

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue
164 Atlas of Interoccurrence Intervals for Selected Thresholds of Daily Precipitation in Texas 

1057 127.00 4 508 970 -.157 .438 .438 508.00 1 508 29 -1.534 .063 .063

1058 70.78 498 35,247 9001749 .992 .839 .161 133.01 265 35,247 4676164 .036 .514 .486

1059 119.17 6 715 782 -2.696 .004 .004 143.00 5 715 753 -2.242 .013 .013

1060 95.41 254 24,233 3236740 1.428 .923 .077 193.86 125 24,233 1553247 .495 .690 .310

1061 82.50 8 660 2378 -.486 .313 .313 220.00 3 660 873 -.355 .361 .361

1062 115.56 18 2,080 15544 -1.247 .106 .106 346.67 6 2,080 4452 -1.216 .112 .112

1063 271.24 88 23,869 1135563 1.320 .907 .093 596.73 40 23,869 532251 1.259 .896 .104

1064 413.00 3 1,239 1752 -.172 .432 .432 1239.00 1 1,239 469 -.421 .337 .337

1065 86.71 70 6,070 216451 .273 .608 .392 195.81 31 6,070 93547 -.055 .478 .478

1066 78.82 141 11,113 788616 .135 .554 .446 148.17 75 11,113 479448 2.257 .988 .012

1067 61.13 15 917 8299 1.387 .917 .083 131.00 7 917 3822 .875 .809 .191

1068 79.56 9 716 2791 -.695 .244 .244 238.67 3 716 459 -1.718 .043 .043

1069 106.24 51 5,418 148077 .888 .813 .187 216.72 25 5,418 76952 1.180 .881 .119

1070 82.49 427 35,225 7241354 -1.329 .092 .092 142.61 247 35,225 4180575 -1.062 .144 .144

1071 60.78 323 19,631 3409304 2.346 .991 .010 116.16 169 19,631 1731489 .986 .838 .162

1072 75.82 22 1,668 16205 -.949 .171 .171 151.64 11 1,668 8240 -.585 .279 .279

1073 -- -- -- -- -- -- -- -- -- -- -- -- -- --

1074 51.82 581 30,105 9081448 1.604 .946 .054 88.54 340 30,105 5206102 .551 .709 .291

1075 103.56 25 2,589 30828 -.411 .341 .341 258.90 10 2,589 14598 .699 .758 .242

1076 86.76 208 18,047 1979475 1.365 .914 .086 155.58 116 18,047 1079778 .589 .722 .278

1077 78.14 44 3,438 74735 -.137 .446 .446 137.52 25 3,438 41089 -.380 .352 .352

1078 205.32 134 27,513 1934838 .995 .840 .160 410.64 67 27,513 971878 .772 .780 .220

1079 107.53 291 31,290 4759680 1.343 .910 .090 211.42 148 31,290 2353586 .347 .636 .364

1080 69.14 7 484 2318 1.688 .954 .046 121.00 4 484 1146 .637 .738 .262

1081 136.10 156 21,232 1668294 .159 .563 .437 268.76 79 21,232 843101 .081 .532 .468

1082 131.68 104 13,695 760743 1.206 .886 .114 291.38 47 13,695 369920 1.774 .962 .038

1083 244.92 63 15,430 493460 .210 .583 .417 467.58 33 15,430 276450 .854 .803 .197

1084 48.68 25 1,217 15567 .202 .580 .420 71.59 17 1,217 9458 -.612 .270 .270

1085 59.57 610 36,335 11268122 .718 .763 .237 108.79 334 36,335 6014412 -.279 .390 .390

1086 120.21 42 5,049 92553 -1.427 .077 .077 280.50 18 5,049 41768 -.594 .276 .276

1087 501.79 28 14,050 192994 -.173 .431 .431 1405.00 10 14,050 62157 -.631 .264 .264

1088 34.65 65 2,252 79273 1.161 .877 .123 52.37 43 2,252 55300 1.614 .947 .053

1089 118.60 10 1,186 5808 -.113 .455 .455 296.50 4 1,186 1918 -.663 .254 .254

1090 104.95 97 10,180 508553 .512 .696 .304 248.29 41 10,180 224963 .865 .806 .194

1091 169.83 116 19,700 1191423 .797 .787 .213 419.15 47 19,700 493082 .773 .780 .220

1092 24.60 5 123 135 -2.173 .015 .015 -- -- -- -- -- -- --

1093 46.18 103 4,757 239521 -.392 .348 .348 97.08 49 4,757 100290 -1.691 .045 .045

1094 64.84 398 25,807 5544066 2.748 .997 .003 107.08 241 25,807 3408715 2.585 .995 .005

1095 61.81 32 1,978 28691 -.916 .180 .180 109.89 18 1,978 18839 .428 .666 .334

1096 156.59 122 19,104 1252153 1.425 .923 .077 382.08 50 19,104 517136 1.014 .845 .155

1097 63.85 298 19,028 3117552 2.978 .999 .001 136.89 139 19,028 1448153 1.941 .974 .026

1098 89.54 165 14,774 1172629 -.844 .199 .199 173.81 85 14,774 579272 -1.237 .108 .108

1099 -- -- -- -- -- -- -- -- -- -- -- -- -- --

1100 94.00 30 2,820 40616 -.378 .353 .353 216.92 13 2,820 21094 .942 .827 .173

1101 62.39 468 29,198 7206874 2.054 .980 .020 121.15 241 29,198 3531100 0.097 .539 .461

1102 143.46 220 31,561 3561258 .663 .746 .254 281.80 112 31,561 1811742 .460 .677 .323

1103 697.73 15 10,466 84462 .510 .695 .305 1744.33 6 10,466 27987 -.461 .322 .322

1104 67.35 116 7,812 462838 .401 .656 .344 130.20 60 7,812 247199 .735 .769 .231

Table 6. Summary of interoccurrence intervals for daily precipitation thresholds of 1.5 and 2.0 inches—Continued

Seq.

no.

Daily precipitation threshold of 1.5 inches and greater Daily precipitation threshold of 2.0 inches and greater

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue
Table 6 165

1105 65.56 202 13,243 1333156 -.081 .468 .468 128.57 103 13,243 663544 -.476 .317 .317

1106 123.58 182 22,491 2039179 -.086 .466 .466 234.28 96 22,491 1132891 .838 .799 .201

1107 123.85 13 1,610 7847 -1.562 .059 .059 402.50 4 1,610 2348 -.938 .174 .174

1108 -- -- -- -- -- -- -- -- -- -- -- -- -- --

1109 112.68 31 3,493 53956 -.033 .487 .487 232.87 15 3,493 21872 -1.108 .134 .134

1110 71.63 49 3,510 79582 -.904 .183 .183 117.00 30 3,510 49646 -.541 .294 .294

1111 160.86 14 2,252 9832 -2.439 .007 .007 563.00 4 2,252 2601 -1.464 .072 .072

1112 44.84 268 12,016 1701706 1.612 .947 .053 84.03 143 12,016 910721 1.243 .893 .107

1113 187.89 157 29,498 2235229 -.753 .226 .226 404.08 73 29,498 1000734 -1.044 .148 .148

1114 87.22 139 12,124 830060 -.304 .380 .380 151.55 80 12,124 496832 .379 .648 .352

1115 157.11 37 5,813 114369 .669 .748 .252 363.31 16 5,813 37527 -1.337 .091 .091

1116 48.43 30 1,453 21242 -.241 .405 .405 90.81 16 1,453 11405 -.131 .448 .448

1117 65.53 240 15,727 1832354 -.780 .218 .218 125.82 125 15,727 969428 -.266 .395 .395

1118 80.00 10 800 3818 -.249 .402 .402 160.00 5 800 1688 -.604 .273 .273

1119 80.70 94 7,586 336595 -.940 .174 .174 140.48 54 7,586 211374 .407 .658 .342

1120 154.82 158 24,462 1911338 -.238 .406 .406 321.87 76 24,462 861023 -1.113 .133 .133

1121 109.91 270 29,675 3734837 -1.927 .027 .027 211.96 140 29,675 1934999 -1.403 .080 .080

1122 92.82 11 1,021 4911 -.721 .236 .236 170.17 6 1,021 3225 .224 .589 .411

1123 96.22 237 22,804 2696196 -.060 .476 .476 190.03 120 22,804 1369054 .011 .505 .495

1124 97.93 14 1,371 8220 -.930 .176 .176 171.38 8 1,371 4427 -.944 .173 .173

1125 85.46 33 2,820 45952 -.124 .451 .451 165.88 17 2,820 20660 -.986 .162 .162

1126 120.72 32 3,863 60945 -.137 .446 .446 227.24 17 3,863 31299 -.334 .369 .369

1127 142.00 188 26,696 2344011 -1.565 .059 .059 287.05 93 26,696 1082879 -2.133 .016 .016

1128 132.07 73 9,641 334600 -.727 .234 .234 292.15 33 9,641 154939 -.259 .398 .398

1129 257.00 14 3,598 24978 -.054 .479 .479 449.75 8 3,598 15105 .243 .596 .404

1130 755.00 1 755 192 -.851 .197 .197 -- -- -- -- -- -- --

1131 73.69 188 13,853 1374273 1.315 .906 .094 138.53 100 13,853 763348 1.768 .961 .039

1132 348.00 2 696 453 -.855 .196 .196 696.00 1 696 227 -.602 .274 .274

1133 69.64 145 10,098 681514 -1.441 .075 .075 138.33 73 10,098 349664 -.759 .224 .224

1134 228.33 3 685 987 -.118 .453 .453 342.50 2 685 392 -1.048 .147 .147

1135 35.86 22 789 6540 -2.002 .023 .023 60.69 13 789 4217 -1.110 .134 .134

1136 228.48 122 27,875 1682413 -.202 .420 .420 536.06 52 27,875 696395 -.489 .313 .313

1137 92.94 206 19,145 1978185 .079 .531 .469 187.70 102 19,145 1020262 .786 .784 .216

1138 1234.50 2 2,469 3625 1.147 .874 .126 -- -- -- -- -- -- --

1139 519.50 6 3,117 7634 -.779 .218 .218 1558.50 2 3,117 2825 -.230 .409 .409

1140 128.01 87 11,137 440260 -1.474 .070 .070 227.29 49 11,137 265712 -.318 .375 .375

1141 47.09 424 19,965 4578374 2.914 .998 .002 84.24 237 19,965 2706806 3.843 1.000 0

1142 49.20 665 32,715 10976721 .406 .658 .342 88.42 370 32,715 6265283 1.173 .879 .121

1143 231.15 39 9,015 164377 -.702 .241 .241 751.25 12 9,015 43397 -1.186 .118 .118

1144 77.45 31 2,401 37794 .150 .560 .440 141.24 17 2,401 20669 .091 .536 .464

1145 238.17 6 1,429 5302 1.005 .842 .158 476.33 3 1,429 2335 .268 .606 .394

1146 184.88 144 26,623 1925543 .094 .538 .462 451.24 59 26,623 791940 .111 .544 .456

1147 105.22 59 6,208 202021 1.372 .915 .085 206.93 30 6,208 99617 .662 .746 .254

1148 185.71 70 13,000 466484 .366 .643 .357 325.00 40 13,000 251436 -.361 .359 .359

1149 82.77 146 12,084 887598 0.130 .552 .448 132.79 91 12,084 594306 1.337 .909 .091

1150 210.05 64 13,443 454448 .782 .783 .217 463.55 29 13,443 212659 .849 .802 .198

1151 95.17 12 1,142 6325 -.462 .322 .322 228.40 5 1,142 2767 -.119 .452 .452

1152 70.77 374 26,466 5005695 .383 .649 .351 144.62 183 26,466 2527223 1.022 .846 .154

Table 6. Summary of interoccurrence intervals for daily precipitation thresholds of 1.5 and 2.0 inches—Continued

Seq.

no.

Daily precipitation threshold of 1.5 inches and greater Daily precipitation threshold of 2.0 inches and greater

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue
166 Atlas of Interoccurrence Intervals for Selected Thresholds of Daily Precipitation in Texas 

1153 34.79 14 487 3376 -.063 .475 .475 48.70 10 487 2350 -.191 .424 .424

1154 92.49 141 13,041 905434 -.312 .377 .377 207.00 63 13,041 409885 -.030 .488 .488

1155 52.65 26 1,369 16023 -.880 .189 .189 85.56 16 1,369 7989 -1.874 .030 .030

1156 82.89 157 13,013 1046698 .535 .704 .296 153.09 85 13,013 538228 -.428 .334 .334

1157 116.43 155 18,047 1552037 2.365 .991 .009 265.40 68 18,047 678758 1.517 .935 .065

1158 50.89 70 3,562 126709 .237 .594 .406 107.94 33 3,562 65587 1.154 .876 .124

1159 68.62 537 36,849 10150087 1.039 .851 .149 124.07 297 36,849 5522074 .273 .607 .393

1160 107.77 13 1,401 9637 .364 .642 .358 280.20 5 1,401 1931 -1.738 .041 .041

1161 154.60 37 5,720 104316 -.150 .440 .440 336.47 17 5,720 45733 -.424 .336 .336

1162 1210.00 1 1,210 1122 1.480 .931 .069 -- -- -- -- -- -- --

1163 790.00 4 3,160 4035 -1.252 .105 .105 -- -- -- -- -- -- --

1164 54.74 350 19,160 3603650 2.422 .992 .008 101.38 189 19,160 1981519 2.248 .988 .012

1165 125.75 79 9,934 415115 .892 .814 .186 283.83 35 9,934 166269 -.447 .328 .328

1166 43.60 275 11,989 1751554 1.796 .964 .036 85.03 141 11,989 920716 1.837 .967 .033

1167 55.79 121 6,751 417553 .425 .665 .335 112.52 60 6,751 196033 -.430 .333 .333

1168 146.94 17 2,498 25616 1.474 .930 .070 416.33 6 2,498 6826 -.378 .353 .353

1169 624.50 2 1,249 1033 -.424 .336 .336 -- -- -- -- -- -- --

1170 45.43 364 16,537 3230145 2.420 .992 .008 95.59 173 16,537 1536130 1.683 .954 .046

1171 74.68 164 12,247 1013600 .206 .582 .418 157.01 78 12,247 475085 -.082 .467 .467

1172 59.95 323 19,365 3161625 .340 .633 .367 111.29 174 19,365 1733915 .667 .747 .253

1173 94.75 251 23,783 2865573 -1.096 .137 .137 171.10 139 23,783 1592328 -.749 .227 .227

1174 103.67 49 5,080 140326 1.546 .939 .061 175.17 29 5,080 84778 1.408 .920 .080

1175 113.02 240 27,125 3329847 .617 .731 .269 248.85 109 27,125 1509606 .383 .649 .351

1176 327.00 2 654 596 -.217 .414 .414 654.00 1 654 257 -.371 .355 .355

1177 56.84 25 1,421 21156 1.655 .951 .049 129.18 11 1,421 7314 -.369 .356 .356

1178 88.80 201 17,848 1863693 .958 .831 .169 174.98 102 17,848 911754 .029 .512 .488

1179 116.11 151 17,533 1297811 -.417 .338 .338 240.18 73 17,533 633221 -.156 .438 .438

1180 104.69 16 1,675 12670 -.377 .353 .353 152.27 11 1,675 8808 -.252 .400 .400

1181 401.67 3 1,205 2040 .386 .650 .350 602.50 2 1,205 886 -.649 .258 .258

1182 37.24 260 9,681 1320151 1.368 .914 .086 69.15 140 9,681 702401 .748 .773 .227

1183 48.65 403 19,606 4316784 3.223 .999 .001 92.48 212 19,606 2286293 2.525 .994 .006

1184 1147.57 7 8,033 28835 .117 .547 .453 8033.00 1 8,033 3174 -.363 .358 .358

1185 90.06 95 8,556 401948 -.185 .426 .426 225.16 38 8,556 171127 .562 .713 .287

1186 51.51 117 6,027 359586 .372 .645 .355 92.72 65 6,027 210942 1.074 .859 .141

1187 37.14 309 11,476 1892738 2.055 .980 .020 65.95 174 11,476 1083073 1.937 .974 .026

1188 526.63 19 10,006 104361 .739 .770 .230 909.64 11 10,006 63698 .905 .817 .183

1189 110.10 174 19,158 1799440 1.819 .966 .034 258.89 74 19,158 749628 .857 .804 .196

1190 57.62 331 19,072 3327483 1.708 .956 .044 105.96 180 19,072 1899021 2.471 .993 .007

1191 181.00 4 724 867 -1.390 .082 .082 241.33 3 724 728 -.989 .161 .161

1192 129.68 50 6,484 165442 .253 .600 .400 294.73 22 6,484 66805 -.515 .303 .303

1193 68.19 112 7,637 434858 .308 .621 .379 117.49 65 7,637 235879 -.693 .244 .244

1194 54.46 153 8,332 693949 1.901 .971 .029 105.47 79 8,332 386661 2.692 .996 .004

1195 47.32 47 2,224 54817 .580 .719 .281 105.91 21 2,224 23830 .163 .565 .435

1196 54.44 118 6,424 371285 -.384 .351 .351 112.70 57 6,424 179161 -.280 .390 .390

1197 68.56 289 19,815 3040271 1.820 .966 .034 140.53 141 19,815 1487191 1.329 .908 .092

1198 114.89 79 9,076 398461 1.716 .957 .043 245.30 37 9,076 187226 1.212 .887 .113

1199 120.00 3 360 485 -.306 .380 .380 180.00 2 360 270 -.612 .270 .270

1200 102.06 141 14,391 1080010 1.327 .908 .092 194.47 74 14,391 567467 .979 .836 .164

Table 6. Summary of interoccurrence intervals for daily precipitation thresholds of 1.5 and 2.0 inches—Continued

Seq.

no.

Daily precipitation threshold of 1.5 inches and greater Daily precipitation threshold of 2.0 inches and greater

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue
Table 6 167

1201 191.70 10 1,917 10029 .254 .600 .400 273.86 7 1,917 7124 .283 .611 .389

1202 213.19 91 19,400 946895 1.202 .885 .115 451.16 43 19,400 510077 2.532 .994 .006

1203 149.47 105 15,694 681239 -3.074 .001 .001 290.63 54 15,694 361415 -1.872 .031 .031

1204 188.79 82 15,481 723291 2.189 .986 .014 322.52 48 15,481 426426 1.773 .962 .038

1205 44.12 147 6,485 511435 1.533 .937 .063 93.99 69 6,485 244449 1.332 .909 .091

1206 56.04 189 10,592 977250 -.564 .287 .287 109.20 97 10,592 451910 -2.052 .020 .020

1207 54.50 112 6,104 348903 .380 .648 .352 105.24 58 6,104 174196 -.210 .417 .417

1208 214.35 91 19,506 907317 .369 .644 .356 527.19 37 19,506 345993 -.434 .332 .332

1209 -- -- -- -- -- -- -- -- -- -- -- -- -- --

1210 62.86 59 3,709 95745 -1.662 .048 .048 90.46 41 3,709 73143 -.422 .337 .337

1211 109.19 257 28,061 3577743 -.216 .414 .414 179.88 156 28,061 2105669 -.821 .206 .206

1212 108.25 89 9,634 459152 1.160 .877 .123 181.77 53 9,634 288865 1.658 .951 .049

1213 107.33 51 5,474 131581 -.709 .239 .239 248.82 22 5,474 49634 -1.427 .077 .077

1214 72.40 10 724 4432 1.229 .890 .110 103.43 7 724 3099 1.022 .847 .154

1215 406.52 21 8,537 81080 -.758 .224 .224 948.56 9 8,537 22639 -2.134 .016 .016

1216 336.45 75 25,234 812815 -2.116 .017 .017 788.56 32 25,234 384771 -.460 .323 .323

1217 62.82 209 13,130 1360704 -.208 .418 .418 110.34 119 13,130 724689 -1.368 .086 .086

1218 52.73 62 3,269 99556 -.240 .405 .405 108.97 30 3,269 50177 .221 .587 .413

1219 65.88 298 19,632 3210557 2.917 .998 .002 121.94 161 19,632 1708818 1.786 .963 .037

1220 615.12 34 20,914 374244 .531 .702 .298 1742.83 12 20,914 135299 .469 .681 .319

1221 117.54 50 5,877 144443 -.207 .418 .418 293.85 20 5,877 56915 -.245 .403 .403

1222 -- -- -- -- -- -- -- -- -- -- -- -- -- --

1223 63.67 86 5,476 258425 1.566 .941 .059 111.76 49 5,476 144845 .965 .833 .167

1224 70.64 28 1,978 32394 1.556 .940 .060 141.29 14 1,978 14835 .463 .678 .322

1225 63.07 42 2,649 54554 -.217 .414 .414 120.41 22 2,649 26322 -.785 .216 .216

1226 238.05 92 21,901 915777 -1.512 .065 .065 576.34 38 21,901 379807 -.932 .176 .176

1227 81.12 77 6,246 244193 .235 .593 .407 178.46 35 6,246 126227 1.586 .944 .056

1228 97.17 258 25,070 3291462 .494 .689 .311 181.67 138 25,070 1753871 .283 .611 .389

1229 61.51 240 14,762 1862289 1.376 .916 .084 103.23 143 14,762 1114698 1.162 .877 .123

1230 61.90 232 14,360 1811664 2.311 .990 .010 101.84 141 14,360 1145307 2.701 .997 .003

1231 48.69 16 779 6383 .168 .567 .433 86.56 9 779 3901 .586 .721 .279

1232 57.35 17 975 10618 2.008 .978 .022 121.88 8 975 5901 2.514 .994 .006

1233 81.89 65 5,323 199740 2.159 .985 .015 120.98 44 5,323 135922 1.846 .968 .032

1234 105.32 106 11,164 606457 .445 .672 .328 192.48 58 11,164 333149 .383 .649 .351

1235 86.25 48 4,140 109279 1.198 .884 .116 153.33 27 4,140 59643 .604 .727 .273

1236 65.18 34 2,216 33282 -1.177 .120 .120 123.11 18 2,216 16739 -1.181 .119 .119

1237 62.88 209 13,142 1455336 1.495 .933 .067 126.37 104 13,142 734264 1.315 .906 .094

1238 79.36 321 25,474 4060181 -.216 .415 .415 175.68 145 25,474 1936417 1.011 .844 .156

1239 65.72 229 15,049 1659534 -.967 .167 .167 133.18 113 15,049 861746 .249 .598 .402

1240 268.14 7 1,877 5980 -.411 .340 .340 469.25 4 1,877 3500 -.234 .407 .407

1241 52.38 345 18,072 3192693 .777 .781 .219 105.68 171 18,072 1637315 1.351 .912 .088

1242 62.25 12 747 6316 2.455 .993 .007 106.71 7 747 4019 2.462 .993 .007

1243 41.32 426 17,604 3847659 .934 .825 .175 68.23 258 17,604 2324703 .659 .745 .255

1244 57.69 332 19,152 3196340 .170 .567 .433 114.68 167 19,152 1602897 .052 .521 .479

1245 141.48 134 18,958 1327389 0.903 .817 .183 296.22 64 18,958 713745 2.446 .993 .007

1246 144.50 16 2,312 20358 .698 .757 .243 289.00 8 2,312 11212 1.040 .851 .149

1247 125.47 121 15,182 883773 -.721 .236 .236 230.03 66 15,182 499960 -.029 .488 .488

1248 20.33 3 61 135 1.426 .923 .077 -- -- -- -- -- -- --

Table 6. Summary of interoccurrence intervals for daily precipitation thresholds of 1.5 and 2.0 inches—Continued

Seq.

no.

Daily precipitation threshold of 1.5 inches and greater Daily precipitation threshold of 2.0 inches and greater

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue
168 Atlas of Interoccurrence Intervals for Selected Thresholds of Daily Precipitation in Texas 

1249 95.56 129 12,327 828694 .831 .797 .203 192.61 64 12,327 388224 -.219 .413 .413

1250 66.29 556 36,857 10230399 -.063 .475 .475 130.70 282 36,857 5236363 .221 .588 .412

1251 221.60 5 1,108 1406 -1.907 .028 .028 554.00 2 1,108 376 -1.618 .053 .053

1252 76.61 463 35,470 8683065 2.141 .984 .016 164.21 216 35,470 4125784 1.961 .975 .025

1253 47.50 94 4,465 205360 -.360 .360 .360 91.12 49 4,465 106163 -.358 .360 .360

1254 30.40 15 456 3176 -.479 .316 .316 41.46 11 456 2552 .101 .540 .460

1255 58.90 228 13,428 1480272 -.863 .194 .194 104.91 128 13,428 855056 -.099 .461 .461

1256 116.99 175 20,473 1975168 2.351 .991 .009 227.48 90 20,473 1027540 1.895 .971 .029

1257 103.33 189 19,529 1947139 1.312 .905 .095 189.60 103 19,529 1051526 .800 .788 .212

1258 58.60 62 3,633 110345 -.276 .391 .391 103.80 35 3,633 62296 -.207 .418 .418

1259 -- -- -- -- -- -- -- -- -- -- -- -- -- --

1260 54.87 397 21,784 4700163 3.001 .999 .001 96.39 226 21,784 2625210 1.731 .958 .042

1261 115.20 71 8,179 327398 1.862 .969 .031 247.85 33 8,179 162706 2.046 .980 .020

1262 72.13 16 1,154 7150 -1.562 .059 .059 128.22 9 1,154 4010 -1.184 .118 .118

1263 86.00 6 516 1536 -.033 .487 .487 172.00 3 516 726 -.186 .426 .426

1264 172.00 9 1,548 8249 .957 .831 .169 309.60 5 1,548 4254 .384 .650 .350

1265 41.61 83 3,454 149564 .685 .753 .247 80.33 43 3,454 93061 2.875 .998 .002

1266 79.68 239 19,044 2226666 -.578 .282 .282 160.03 119 19,044 1198261 1.086 .861 .139

1267 97.71 138 13,484 953977 .516 .697 .303 175.12 77 13,484 556622 1.098 .864 .136

1268 90.80 189 17,161 1628591 .101 .540 .460 157.44 109 17,161 989206 1.043 .851 .149

1269 -- -- -- -- -- -- -- -- -- -- -- -- -- --

1270 145.80 15 2,187 15052 -.552 .290 .290 364.50 6 2,187 5678 -.571 .284 .284

1271 95.83 366 35,073 5908720 -2.631 .004 .004 193.77 181 35,073 2729065 -3.267 .001 .001

1272 107.87 37 3,991 67718 -.873 .192 .192 307.00 13 3,991 21325 -1.111 .133 .133

1273 89.90 106 9,529 484486 -.726 .234 .234 186.84 51 9,529 260421 .887 .812 .188

1274 37.75 163 6,153 522355 .921 .821 .179 65.46 94 6,153 295484 .365 .643 .357

1275 33.39 108 3,606 203821 .841 .800 .200 54.64 66 3,606 120769 .209 .583 .417

1276 53.14 104 5,527 272624 -.908 .182 .182 83.74 66 5,527 170645 -.906 .182 .182

1277 25.60 100 2,560 137205 1.246 .894 .107 39.39 65 2,560 93669 1.757 .961 .039

1278 56.60 512 28,977 7646493 1.207 .886 .114 103.12 281 28,977 4263621 1.372 .915 .085

1279 250.17 6 1,501 3184 -1.243 .107 .107 500.33 3 1,501 2286 .046 .518 .482

1280 94.37 57 5,379 178105 2.116 .983 .017 168.09 32 5,379 100932 1.693 .955 .045

1281 63.95 97 6,203 283715 -.971 .166 .166 126.59 49 6,203 145979 -.478 .316 .316

1282 245.00 1 245 221 1.393 .918 .082 -- -- -- -- -- -- --

1283 106.80 49 5,233 146266 1.708 .956 .044 249.19 21 5,233 61636 .966 .833 .167

1284 36.86 265 9,769 1373204 1.717 .957 .043 70.28 139 9,769 746474 2.031 .979 .021

1285 309.65 68 21,056 739611 .473 .682 .318 726.07 29 21,056 343945 1.180 .881 .119

1286 49.72 368 18,295 3430289 .632 .736 .264 97.83 187 18,295 1750470 .552 .710 .290

1287 127.23 47 5,980 152766 1.034 .849 .151 206.21 29 5,980 95641 .961 .832 .168

1288 107.57 112 12,048 656808 -.486 .314 .314 236.24 51 12,048 264079 -1.737 .041 .041

1289 120.59 115 13,868 842370 1.047 .852 .148 277.36 50 13,868 363456 .592 .723 .277

1290 110.00 13 1,430 12071 1.865 .969 .031 238.33 6 1,430 6588 2.273 .988 .012

1291 135.11 9 1,216 6907 1.363 .913 .087 243.20 5 1,216 4125 1.382 .917 .083

1292 53.29 369 19,665 3822435 1.781 .963 .037 100.33 196 19,665 2018817 1.153 .876 .124

1293 73.45 232 17,041 1958471 -0.244 .404 .404 139.68 122 17,041 1019696 -0.365 .358 .358

1294 91.96 55 5,058 129780 -.860 .195 .195 174.41 29 5,058 60243 -1.666 .048 .048

1295 45.57 14 638 6213 2.535 .994 .006 91.14 7 638 2746 1.053 .854 .146

1296 33.26 128 4,257 272239 -.015 .494 .494 61.70 69 4,257 154327 .731 .768 .232

Table 6. Summary of interoccurrence intervals for daily precipitation thresholds of 1.5 and 2.0 inches—Continued

Seq.

no.

Daily precipitation threshold of 1.5 inches and greater Daily precipitation threshold of 2.0 inches and greater

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue
Table 6 169

1297 73.22 37 2,709 48301 -.382 .351 .351 129.00 21 2,709 24573 -1.080 .140 .140

1298 67.50 22 1,485 16752 .207 .582 .418 114.23 13 1,485 10055 .260 .603 .397

1299 49.47 196 9,696 1046312 2.453 .993 .007 93.23 104 9,696 566117 2.169 .985 .015

1300 -- -- -- -- -- -- -- -- -- -- -- -- -- --

1301 59.63 466 27,787 6704412 1.329 .908 .092 105.25 264 27,787 3763077 .730 .767 .233

1302 69.24 270 18,695 2685836 1.827 .966 .034 127.18 147 18,695 1462240 1.347 .911 .089

1303 32.33 9 291 1071 -.946 .172 .172 97.00 3 291 360 -.526 .300 .300

1304 80.89 45 3,640 91438 1.353 .912 .088 165.46 22 3,640 44321 .869 .807 .193

1305 1192.37 19 22,655 227193 .420 .663 .337 4531.00 5 22,655 67950 .774 .780 .220

1306 125.82 119 14,972 853457 -.793 .214 .214 216.99 69 14,972 456871 -1.662 .048 .048

Table 6. Summary of interoccurrence intervals for daily precipitation thresholds of 1.5 and 2.0 inches—Continued

Seq.

no.

Daily precipitation threshold of 1.5 inches and greater Daily precipitation threshold of 2.0 inches and greater

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue
170 Atlas of Interoccurrence Intervals for Selected Thresholds of Daily Precipitation in Texas 

Table 7

Table 7. Summary of interoccurrence intervals for daily precipitation thresholds of 2.5 and 3.0 inches—Continued

Seq.

no.

Daily precipitation threshold of 2.5 inches and greater Daily precipitation threshold of 3.0 inches and greater

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue

1 780.56 25 19,514 212846 -1.103 .135 .135 1393.86 14 19,514 132246 -0.207 .418 .418

2 -- -- -- -- -- -- -- -- -- -- -- -- -- --

3 616.25 32 19,720 291421 -.748 .227 .227 1232.50 16 19,720 171243 .592 .723 .277

4 336.64 25 8,416 102472 -.225 .411 .411 601.14 14 8,416 55451 -.381 .352 .352

5 542.66 35 18,993 409143 2.367 .991 .009 791.38 24 18,993 277041 1.829 .966 .034

6 440.25 8 3,522 17211 1.086 .861 .139 587.00 6 3,522 13216 1.064 .856 .144

7 344.33 24 8,264 66044 -2.834 .002 .002 918.22 9 8,264 28172 -1.260 .104 .104

8 1458.00 1 1,458 1144 .986 .838 .162 -- -- -- -- -- -- --

9 964.33 3 2,893 3144 -.827 .204 .204 964.33 3 2,893 3144 -.827 .204 .204

10 -- -- -- -- -- -- -- -- -- -- -- -- -- --

11 235.39 26 6,120 79568 .001 .500 .500 470.77 13 6,120 27153 -1.982 .024 .024

12 408.98 87 35,581 1591886 .460 .677 .323 741.27 48 35,581 893570 .557 .711 .289

13 341.02 44 15,005 332762 .092 .537 .463 468.91 32 15,005 257755 .721 .765 .235

14 285.39 105 29,966 1666498 1.052 .854 .146 416.19 72 29,966 1160118 1.108 .866 .134

15 427.25 4 1,709 4739 1.339 .910 .090 854.50 2 1,709 1996 .411 .660 .340

16 -- -- -- -- -- -- -- -- -- -- -- -- -- --

17 -- -- -- -- -- -- -- -- -- -- -- -- -- --

18 2503.55 11 27,539 201407 1.894 .971 .029 27539.00 1 27,539 15717 .245 .597 .403

19 179.81 107 19,240 1035566 .108 .543 .457 305.40 63 19,240 636376 .688 .754 .246

20 156.97 39 6,122 116962 -.219 .413 .413 211.10 29 6,122 76831 -1.254 .105 .105

21 229.52 23 5,279 58716 -.273 .393 .393 310.53 17 5,279 45520 .103 .541 .459

22 122.92 281 34,541 4861710 .052 .521 .479 200.82 172 34,541 2907358 -.483 .315 .315

23 395.67 3 1,187 2496 1.206 .886 .114 1187.00 1 1,187 729 .395 .654 .346

24 1094.06 18 19,693 148728 -1.182 .119 .119 1790.27 11 19,693 83292 -1.327 .092 .092

25 474.35 29 13,756 152515 -2.195 .014 .014 724.00 19 13,756 94945 -2.065 .019 .019

26 108.74 286 31,099 4821907 2.468 .993 .007 172.77 180 31,099 3010805 1.759 .961 .039

27 159.90 130 20,787 1294939 -.822 .206 .206 296.96 70 20,787 647462 -1.595 .055 .055

28 364.30 33 12,022 201547 .160 .563 .437 667.89 18 12,022 106342 -.126 .450 .450

29 1221.85 13 15,884 73639 -1.791 .037 .037 1764.89 9 15,884 48731 -1.654 .049 .049

30 115.44 274 31,631 4721196 2.565 .995 .005 158.95 199 31,631 3442734 2.294 .989 .011

31 226.61 80 18,129 752069 .575 .717 .283 412.02 44 18,129 413102 .411 .659 .341

32 369.96 45 16,648 351288 -.723 .235 .235 594.57 28 16,648 190766 -1.664 .048 .048

33 463.66 50 23,183 689340 2.320 .990 .010 858.63 27 23,183 377145 1.845 .968 .032

34 329.27 11 3,622 24206 1.236 .892 .108 452.75 8 3,622 18207 1.258 .896 .104

35 183.79 56 10,292 320280 1.444 .926 .074 233.91 44 10,292 262012 1.806 .965 .035

36 124.51 89 11,081 473113 -.663 .254 .254 167.89 66 11,081 360413 -.202 .420 .420

37 145.48 75 10,911 429388 .742 .771 .229 222.67 49 10,911 273715 .290 .614 .386

38 306.99 73 22,410 816760 -.022 .491 .491 589.74 38 22,410 449418 .593 .723 .277

39 257.04 76 19,535 850611 2.203 .986 .014 527.97 37 19,535 425041 1.855 .968 .032

40 280.51 37 10,379 197938 .325 .628 .373 494.24 21 10,379 115027 .441 .670 .330

41 204.85 121 24,787 1654907 1.973 .976 .024 387.30 64 24,787 936493 2.504 .994 .006

42 148.80 5 744 1210 -1.354 .088 .088 248.00 3 744 639 -1.282 .100 .100

43 534.70 60 32,082 969104 .093 .537 .463 972.18 33 32,082 476370 -.996 .160 .160

44 183.70 107 19,656 1106708 .939 .826 .174 344.84 57 19,656 609769 1.157 .876 .124

45 164.76 115 18,947 1126293 0.628 .735 .265 332.40 57 18,947 604100 1.553 .940 .060

46 251.00 103 25,853 1312353 -.252 .401 .401 403.95 64 25,853 857743 .510 .695 .305

47 254.52 25 6,363 98877 2.106 .982 .018 454.50 14 6,363 54830 1.497 .933 .067

48 225.92 25 5,648 83885 1.630 .948 .052 353.00 16 5,648 58021 1.968 .975 .025

Table 7. Summary of interoccurrence intervals for daily precipitation thresholds of 2.5 and 3.0 inches

[--, not available, no events that equal or exceed the threshold were observed]
Table 7 171

49 302.00 1 302 250 1.136 .872 .128 -- -- -- -- -- -- --

50 305.00 3 915 1990 1.350 .911 .089 457.50 2 915 1175 .696 .757 .243

51 207.08 88 18,223 810265 .171 .568 .432 303.72 60 18,223 534836 -.291 .386 .386

52 189.99 69 13,109 435408 -.536 .296 .296 267.53 49 13,109 306640 -.549 .292 .292

53 61.20 5 306 1166 2.030 .979 .021 76.50 4 306 874 1.483 .931 .069

54 43.50 2 87 61 -.732 .232 .232 87.00 1 87 36 -.299 .383 .383

55 290.15 34 9,865 179514 .711 .761 .239 448.41 22 9,865 128322 1.483 .931 .069

56 1192.50 2 2,385 2248 -.141 .444 .444 1192.50 2 2,385 2248 -.141 .444 .444

57 1030.47 19 19,579 198078 .490 .688 .312 1957.90 10 19,579 96866 -.058 .477 .477

58 -- -- -- -- -- -- -- -- -- -- -- -- -- --

59 510.23 71 36,226 1338771 .599 .725 .275 754.71 48 36,226 815088 -.750 .227 .227

60 -- -- -- -- -- -- -- -- -- -- -- -- -- --

61 2322.08 12 27,865 146967 -.726 .234 .234 3483.13 8 27,865 103239 -.361 .359 .359

62 -- -- -- -- -- -- -- -- -- -- -- -- -- --

63 2039.00 1 2,039 878 -.240 .405 .405 2039.00 1 2,039 878 -.240 .405 .405

64 -- -- -- -- -- -- -- -- -- -- -- -- -- --

65 247.40 30 7,422 108434 -.247 .403 .403 436.59 17 7,422 64978 .214 .585 .415

66 259.33 9 2,334 8773 -.856 .196 .196 333.43 7 2,334 7259 -.511 .305 .305

67 238.21 56 13,340 395815 .774 .780 .220 392.35 34 13,340 236244 .422 .663 .337

68 1745.67 3 5,237 8650 .303 .619 .381 -- -- -- -- -- -- --

69 2458.50 2 4,917 7857 1.465 .928 .072 4917.00 1 4,917 3035 .406 .658 .342

70 207.20 5 1,036 3477 1.326 .908 .092 259.00 4 1,036 2786 1.194 .884 .116

71 762.00 1 762 472 .414 .660 .340 762.00 1 762 472 .414 .660 .340

72 335.85 13 4,366 26334 -.450 .326 .326 873.20 5 4,366 12331 .502 .692 .308

73 271.80 46 12,503 261089 -1.082 .140 .140 520.96 24 12,503 117759 -1.825 .034 .034

74 134.22 9 1,208 4712 -.692 .245 .245 172.57 7 1,208 3172 -1.145 .126 .126

75 131.66 178 23,435 2317446 2.567 .995 .005 203.78 115 23,435 1544566 2.716 .997 .003

76 288.50 4 1,154 3461 1.731 .958 .042 577.00 2 1,154 2172 2.161 .985 .015

77 104.20 152 15,838 1264332 1.076 .859 .141 179.98 88 15,838 711821 .349 .636 .364

78 241.33 3 724 631 -1.257 .104 .104 241.33 3 724 631 -1.257 .104 .104

79 194.33 3 583 1150 .945 .828 .172 -- -- -- -- -- -- --

80 120.27 296 35,599 5290243 .122 .549 .451 183.50 194 35,599 3467659 .102 .541 .459

81 114.85 123 14,126 918689 1.104 .865 .135 170.19 83 14,126 630506 1.192 .883 .117

82 162.45 78 12,671 458369 -1.108 .134 .134 248.45 51 12,671 301131 -.841 .200 .200

83 252.84 141 35,650 2662734 1.223 .889 .111 434.76 82 35,650 1497925 .389 .651 .349

84 177.55 44 7,812 163663 -.548 .292 .292 325.50 24 7,812 92181 -.142 .444 .444

85 183.89 9 1,655 8082 .443 .671 .329 331.00 5 1,655 4158 .019 .508 .492

86 253.54 57 14,452 430537 .592 .723 .277 466.19 31 14,452 218102 -.254 .400 .400

87 242.60 5 1,213 4583 1.980 .976 .024 404.33 3 1,213 3418 2.636 .996 .004

88 279.41 46 12,853 300551 .196 .578 .422 357.03 36 12,853 218023 -.599 .275 .275

89 359.79 53 19,069 531418 .651 .742 .258 681.04 28 19,069 296662 1.020 .846 .154

90 304.38 21 6,392 69736 .310 .622 .378 581.09 11 6,392 41225 .992 .839 .161

91 459.67 27 12,411 156385 -.600 .274 .274 886.50 14 12,411 87025 .011 .504 .496

92 252.76 49 12,385 299125 -.172 .432 .432 476.35 26 12,385 153504 -.412 .340 .340

93 141.60 15 2,124 15712 -0.092 .463 .463 236.00 9 2,124 9429 -0.070 .472 .472

94 -- -- -- -- -- -- -- -- -- -- -- -- -- --

95 258.50 4 1,034 1316 -1.260 .104 .104 344.67 3 1,034 1074 -.923 .178 .178

96 811.82 17 13,801 134009 1.017 .845 .155 1533.44 9 13,801 64895 .234 .592 .408

Table 7. Summary of interoccurrence intervals for daily precipitation thresholds of 2.5 and 3.0 inches—Continued

Seq.

no.

Daily precipitation threshold of 2.5 inches and greater Daily precipitation threshold of 3.0 inches and greater

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue
172 Atlas of Interoccurrence Intervals for Selected Thresholds of Daily Precipitation in Texas 

97 -- -- -- -- -- -- -- -- -- -- -- -- -- --

98 1002.32 19 19,044 195478 .608 .728 .272 1904.40 10 19,044 109987 .849 .802 .198

99 114.00 1 114 98 1.246 .894 .106 -- -- -- -- -- -- --

100 381.07 75 28,580 1185372 1.590 .944 .056 595.42 48 28,580 732062 .807 .790 .210

101 354.27 26 9,211 142806 1.701 .956 .044 575.69 16 9,211 84012 .971 .834 .166

102 158.20 5 791 2007 .058 .523 .477 263.67 3 791 791 -1.000 .159 .159

103 294.87 127 37,448 2589350 1.735 .959 .041 492.74 76 37,448 1521393 1.044 .852 .148

104 418.40 15 6,276 42880 -.597 .275 .275 784.50 8 6,276 26210 .216 .585 .415

105 209.10 49 10,246 232876 -.877 .190 .190 341.53 30 10,246 146141 -.466 .321 .321

106 -- -- -- -- -- -- -- -- -- -- -- -- -- --

107 374.35 20 7,487 87877 1.346 .911 .089 623.92 12 7,487 53075 1.089 .862 .138

108 208.62 179 37,342 3407032 .450 .674 .326 339.47 110 37,342 2084232 .269 .606 .394

109 113.48 127 14,412 879085 -.770 .221 .221 189.63 76 14,412 495437 -1.440 .075 .075

110 197.22 176 34,710 3327355 2.053 .980 .020 357.84 97 34,710 1923601 2.434 .993 .007

111 313.50 4 1,254 2247 -.361 .359 .359 627.00 2 1,254 1107 -.287 .387 .387

112 740.48 31 22,955 318355 -1.015 .155 .155 1275.28 18 22,955 209701 .111 .544 .456

113 601.25 4 2,405 4123 -.495 .310 .310 1202.50 2 2,405 2870 .474 .682 .318

114 1003.00 2 2,006 2525 .634 .737 .263 2006.00 1 2,006 1913 1.572 .942 .058

115 9031.00 2 18,062 6370 -1.586 .056 .056 -- -- -- -- -- -- --

116 829.29 7 5,805 17441 -.649 .258 .258 2902.50 2 5,805 3281 -1.065 .144 .144

117 1280.93 15 19,214 181524 1.742 .959 .041 2401.75 8 19,214 75272 -.101 .460 .460

118 1011.00 1 1,011 355 -.516 .303 .303 1011.00 1 1,011 355 -.516 .303 .303

119 336.42 82 27,586 1076588 -.755 .225 .225 562.98 49 27,586 631094 -.803 .211 .211

120 147.50 130 19,175 1381499 2.141 .984 .016 245.83 78 19,175 880399 2.712 .997 .003

121 244.79 75 18,359 796992 2.365 .991 .009 390.62 47 18,359 496744 1.797 .964 .036

122 617.36 14 8,643 62402 .204 .581 .419 1728.60 5 8,643 17010 -.824 .205 .205

123 367.13 94 34,510 1568151 -.557 .289 .289 639.07 54 34,510 874522 -.782 .217 .217

124 235.94 32 7,550 119499 -.106 .458 .458 290.39 26 7,550 90579 -.681 .248 .248

125 474.54 50 23,727 648400 1.140 .873 .127 719.00 33 23,727 433923 1.078 .859 .141

126 201.06 18 3,619 33600 .232 .592 .408 329.00 11 3,619 24953 1.457 .927 .073

127 1076.94 18 19,385 179312 .204 .581 .419 1762.27 11 19,385 110086 .187 .574 .426

128 149.11 73 10,885 402170 .181 .572 .428 222.14 49 10,885 294633 1.271 .898 .102

129 332.78 59 19,634 566782 -.285 .388 .388 613.56 32 19,634 284584 -.922 .178 .178

130 418.25 63 26,350 840489 .173 .569 .431 908.62 29 26,350 427952 1.120 .869 .131

131 380.50 2 761 1011 .805 .789 .211 380.50 2 761 1011 .805 .789 .211

132 222.87 63 14,041 440646 -.051 .480 .480 484.17 29 14,041 225906 1.022 .847 .153

133 199.46 182 36,302 3490836 1.325 .907 .093 297.56 122 36,302 2254321 .345 .635 .365

134 1202.00 1 1,202 308 -.844 .199 .199 1202.00 1 1,202 308 -.844 .199 .199

135 -- -- -- -- -- -- -- -- -- -- -- -- -- --

136 356.54 87 31,019 1473343 1.485 .931 .069 633.04 49 31,019 862816 1.641 .950 .050

137 392.44 9 3,532 20349 1.457 .927 .073 706.40 5 3,532 12828 1.754 .960 .040

138 224.91 34 7,647 154138 1.875 .970 .030 402.47 19 7,647 90641 1.870 .969 .031

139 -- -- -- -- -- -- -- -- -- -- -- -- -- --

140 645.00 2 1,290 435 -1.624 .052 .052 645.00 2 1,290 435 -1.624 .052 .052

141 205.19 52 10,670 263527 -0.626 .266 .266 333.44 32 10,670 173708 0.172 .568 .432

142 131.61 61 8,028 263580 1.035 .850 .150 243.27 33 8,028 151294 1.415 .921 .079

143 164.84 109 17,968 924451 -1.012 .156 .156 299.47 60 17,968 533337 -.142 .444 .444

144 655.62 21 13,768 149917 .294 .616 .384 1251.64 11 13,768 85603 .749 .773 .227

Table 7. Summary of interoccurrence intervals for daily precipitation thresholds of 2.5 and 3.0 inches—Continued

Seq.

no.

Daily precipitation threshold of 2.5 inches and greater Daily precipitation threshold of 3.0 inches and greater

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue
Table 7 173

145 970.56 18 17,470 169419 .570 .716 .284 1941.11 9 17,470 84916 .417 .661 .339

146 277.79 102 28,335 1561901 1.414 .921 .079 449.76 63 28,335 911350 .290 .614 .386

147 347.00 56 19,432 601434 1.366 .914 .086 647.73 30 19,432 297521 .197 .578 .422

148 633.50 2 1,267 1050 -.420 .337 .337 633.50 2 1,267 1050 -.420 .337 .337

149 -- -- -- -- -- -- -- -- -- -- -- -- -- --

150 231.20 5 1,156 2774 -.156 .438 .438 385.33 3 1,156 1772 .066 .526 .474

151 438.56 16 7,017 49911 -.768 .221 .221 779.67 9 7,017 24084 -1.233 .109 .109

152 1581.20 5 7,906 18637 -.221 .413 .413 3953.00 2 7,906 4285 -1.122 .131 .131

153 204.03 71 14,486 584167 1.984 .976 .024 344.91 42 14,486 366033 2.281 .989 .011

154 2671.25 4 10,685 6840 -2.355 .009 .009 10685.00 1 10,685 529 -1.561 .059 .059

155 204.18 108 22,051 1319710 1.949 .974 .026 315.01 70 22,051 790596 .353 .638 .362

156 1470.90 10 14,709 63546 -.745 .228 .228 2101.29 7 14,709 38893 -1.121 .131 .131

157 -- -- -- -- -- -- -- -- -- -- -- -- -- --

158 679.00 3 2,037 3059 .003 .501 .499 1018.50 2 2,037 1453 -.702 .241 .241

159 288.44 61 17,595 576742 1.011 .844 .156 488.75 36 17,595 358561 1.373 .915 .085

160 221.52 27 5,981 74811 -.661 .254 .254 351.82 17 5,981 45088 -.808 .210 .210

161 328.88 41 13,484 268673 -.311 .378 .378 499.41 27 13,484 208558 1.311 .905 .095

162 245.48 40 9,819 214241 .996 .840 .160 490.95 20 9,819 99770 .125 .550 .450

163 324.77 106 34,426 1738089 -.845 .199 .199 521.61 66 34,426 1142812 .084 .533 .467

164 259.00 2 518 869 1.660 .952 .048 518.00 1 518 396 .916 .820 .180

165 1185.00 1 1,185 1048 1.332 .908 .092 1185.00 1 1,185 1048 1.332 .908 .092

166 234.48 27 6,331 78383 -.746 .228 .228 316.55 20 6,331 66146 .347 .636 .364

167 1207.00 1 1,207 1190 1.683 .954 .046 1207.00 1 1,207 1190 1.683 .954 .046

168 256.31 55 14,097 416885 .968 .833 .167 414.62 34 14,097 249825 .429 .666 .334

169 152.00 8 1,216 5284 .423 .664 .336 202.67 6 1,216 4055 .473 .682 .318

170 608.40 10 6,084 34897 .806 .790 .210 1014.00 6 6,084 18298 .011 .504 .496

171 433.32 19 8,233 68280 -.959 .169 .169 748.46 11 8,233 36880 -1.066 .143 .143

172 288.02 114 32,834 1944254 .719 .764 .236 505.14 65 32,834 1172530 1.380 .916 .084

173 329.67 6 1,978 7590 1.184 .882 .118 659.33 3 1,978 2760 -.209 .417 .417

174 772.50 8 6,180 21459 -.646 .259 .259 1030.00 6 6,180 14309 -.968 .167 .167

175 154.33 9 1,389 5545 -.587 .279 .279 277.80 5 1,389 2654 -.913 .181 .181

176 267.32 75 20,049 806459 1.090 .862 .138 455.66 44 20,049 497016 1.457 .927 .073

177 845.40 38 32,125 637384 .473 .682 .318 1606.25 20 32,125 337048 .381 .648 .352

178 331.00 1 331 214 .508 .694 .306 331.00 1 331 214 .508 .694 .306

179 4865.00 4 19,460 51880 1.154 .876 .124 -- -- -- -- -- -- --

180 155.81 107 16,672 947815 1.122 .869 .131 287.45 58 16,672 521433 1.035 .850 .150

181 830.53 34 28,238 484641 .097 .539 .461 1486.21 19 28,238 264187 -.115 .454 .454

182 224.71 62 13,932 434624 .086 .534 .466 366.63 38 13,932 283038 .739 .770 .230

183 241.75 8 1,934 7506 -.146 .442 .442 322.33 6 1,934 5308 -.361 .359 .359

184 173.00 5 865 2193 .055 .522 .478 173.00 5 865 2193 .055 .522 .478

185 2204.00 1 2,204 1219 .184 .573 .427 2204.00 1 2,204 1219 .184 .573 .427

186 190.42 12 2,285 14574 .378 .647 .353 326.43 7 2,285 10427 1.392 .918 .082

187 -- -- -- -- -- -- -- -- -- -- -- -- -- --

188 423.43 35 14,820 282007 .895 .815 .185 673.64 22 14,820 174830 .589 .722 .278

189 394.25 67 26,415 795777 -1.428 .077 .077 574.24 46 26,415 557870 -0.961 .168 .168

190 212.48 89 18,911 893344 1.006 .843 .157 370.80 51 18,911 510179 .717 .763 .237

191 400.59 32 12,819 191236 -.663 .254 .254 582.68 22 12,819 123257 -1.023 .153 .153

192 156.69 116 18,176 1203270 2.638 .996 .004 259.66 70 18,176 742700 2.427 .992 .008

Table 7. Summary of interoccurrence intervals for daily precipitation thresholds of 2.5 and 3.0 inches—Continued

Seq.

no.

Daily precipitation threshold of 2.5 inches and greater Daily precipitation threshold of 3.0 inches and greater

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue
174 Atlas of Interoccurrence Intervals for Selected Thresholds of Daily Precipitation in Texas 

193 608.20 20 12,164 161903 2.564 .995 .005 1013.67 12 12,164 93260 1.667 .952 .048

194 306.14 21 6,429 61592 -.695 .244 .244 535.75 12 6,429 35064 -.546 .293 .293

195 4743.00 2 9,486 4829 -1.203 .115 .115 9486.00 1 9,486 3968 -.283 .389 .389

196 306.38 47 14,400 329959 -.296 .384 .384 533.33 27 14,400 186898 -.347 .364 .364

197 269.83 30 8,095 122530 .086 .534 .466 449.72 18 8,095 77178 .436 .669 .331

198 214.66 59 12,665 429778 2.000 .977 .023 395.78 32 12,665 252292 2.401 .992 .008

199 140.91 162 22,827 1902471 .638 .738 .262 271.75 84 22,827 1034376 1.253 .895 .105

200 455.52 31 14,121 168577 -2.216 .013 .013 941.40 15 14,121 85509 -1.292 .098 .098

201 216.41 106 22,939 1164595 -.751 .227 .227 358.42 64 22,939 734411 .007 .503 .497

202 486.00 1 486 383 .998 .841 .159 486.00 1 486 383 .998 .841 .159

203 370.79 38 14,090 297188 1.176 .880 .120 640.46 22 14,090 181011 1.364 .914 .086

204 86.75 16 1,388 10453 -.406 .342 .342 173.50 8 1,388 5632 .071 .528 .472

205 -- -- -- -- -- -- -- -- -- -- -- -- -- --

206 2925.00 1 2,925 398 -1.261 .104 .104 2925.00 1 2,925 398 -1.261 .104 .104

207 -- -- -- -- -- -- -- -- -- -- -- -- -- --

208 2059.75 4 8,239 28652 2.559 .995 .005 2746.33 3 8,239 21841 2.302 .989 .011

209 201.20 76 15,291 633013 1.350 .911 .089 294.06 52 15,291 454271 1.782 .963 .037

210 390.18 11 4,292 36316 3.093 .999 .001 476.89 9 4,292 28800 2.552 .995 .005

211 1020.00 2 2,040 1544 -.596 .276 .276 2040.00 1 2,040 496 -.890 .187 .187

212 304.98 47 14,334 294032 -1.509 .066 .066 511.93 28 14,334 177843 -1.043 .149 .149

213 186.65 17 3,173 24901 -.548 .292 .292 317.30 10 3,173 13107 -.952 .171 .171

214 1162.00 1 1,162 279 -.900 .184 .184 -- -- -- -- -- -- --

215 801.00 1 801 99 -1.304 .096 .096 -- -- -- -- -- -- --

216 758.50 2 1,517 1446 -.115 .454 .454 758.50 2 1,517 1446 -.115 .454 .454

217 459.03 33 15,148 286658 1.462 .928 .072 797.26 19 15,148 172317 1.491 .932 .068

218 840.77 22 18,497 267252 2.547 .995 .005 2055.22 9 18,497 115292 2.001 .977 .023

219 -- -- -- -- -- -- -- -- -- -- -- -- -- --

220 429.84 57 24,501 635948 -1.167 .122 .122 720.62 34 24,501 365656 -1.233 .109 .109

221 81.33 58 4,717 128771 -.774 .220 .220 174.70 27 4,717 64708 .145 .558 .442

222 2197.00 9 19,773 111916 1.340 .910 .090 2824.71 7 19,773 78460 .613 .730 .270

223 464.93 14 6,509 57863 1.750 .960 .040 929.86 7 6,509 26449 .738 .770 .230

224 611.70 10 6,117 25921 -.835 .202 .202 1019.50 6 6,117 17386 -.223 .412 .412

225 182.06 65 11,834 334638 -1.814 .035 .035 328.72 36 11,834 174613 -1.873 .031 .031

226 530.91 63 33,447 962695 -1.186 .118 .118 857.62 39 33,447 635030 -.285 .388 .388

227 600.00 2 1,200 1059 -.288 .387 .387 1200.00 1 1,200 821 .638 .738 .262

228 190.15 179 34,037 3217699 1.304 .904 .096 286.03 119 34,037 2218404 1.803 .964 .036

229 260.29 35 9,110 161576 .138 .555 .445 379.58 24 9,110 112747 .266 .605 .395

230 653.20 49 32,007 805361 .328 .628 .372 1524.14 21 32,007 290316 -1.081 .140 .140

231 246.94 134 33,090 2250790 .305 .620 .380 429.74 77 33,090 1332590 .699 .758 .242

232 156.06 16 2,497 22280 .799 .788 .212 499.40 5 2,497 8092 1.148 .874 .126

233 135.01 128 17,281 1200817 1.680 .954 .046 230.41 75 17,281 682594 .800 .788 .212

234 1035.00 1 1,035 56 -1.545 .061 .061 -- -- -- -- -- -- --

235 220.51 106 23,374 1227879 -.158 .437 .437 477.02 49 23,374 564114 -.181 .428 .428

236 337.82 17 5,743 51500 .393 .653 .347 717.88 8 5,743 31004 1.713 .957 .043

237 157.45 118 18,579 1086052 -0.174 .431 .431 229.37 81 18,579 675300 -1.598 .055 .055

238 1064.75 4 4,259 11242 1.108 .866 .134 1419.67 3 4,259 8583 1.031 .849 .151

239 158.99 109 17,330 1009625 1.247 .894 .106 247.57 70 17,330 690326 2.002 .977 .023

240 3261.75 4 13,047 32182 .808 .790 .210 3261.75 4 13,047 32182 .808 .790 .210

Table 7. Summary of interoccurrence intervals for daily precipitation thresholds of 2.5 and 3.0 inches—Continued

Seq.

no.

Daily precipitation threshold of 2.5 inches and greater Daily precipitation threshold of 3.0 inches and greater

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue
Table 7 175

241 317.00 118 37,406 2192019 -.127 .449 .449 575.48 65 37,406 1111414 -1.198 .116 .116

242 211.05 83 17,517 694820 -.698 .243 .243 350.34 50 17,517 418158 -.553 .290 .290

243 183.00 113 20,679 1156186 -.192 .424 .424 375.98 55 20,679 580662 .271 .607 .393

244 92.00 1 92 7 -1.469 .071 .071 92.00 1 92 7 -1.469 .071 .071

245 561.34 47 26,383 533547 -1.656 .049 .049 909.76 29 26,383 288489 -2.294 .011 .011

246 200.30 100 20,030 996201 -.092 .463 .463 317.94 63 20,030 613952 -.370 .356 .356

247 492.36 62 30,526 943632 -.039 .485 .485 744.54 41 30,526 623684 -.037 .485 .485

248 219.33 9 1,974 11562 1.567 .941 .059 329.00 6 1,974 6197 .197 .578 .422

249 177.35 17 3,015 28270 .736 .769 .231 274.09 11 3,015 18082 .520 .698 .302

250 495.27 15 7,429 55977 .031 .512 .488 675.36 11 7,429 35740 -.720 .236 .236

251 -- -- -- -- -- -- -- -- -- -- -- -- -- --

252 290.38 8 2,323 9986 .366 .643 .357 387.17 6 2,323 7667 .425 .665 .335

253 466.67 3 1,400 2948 1.211 .887 .113 466.67 3 1,400 2948 1.211 .887 .113

254 1391.79 14 19,485 112433 -1.139 .128 .128 3247.50 6 19,485 68184 .706 .760 .240

255 165.24 117 19,333 1283998 2.535 .994 .006 284.31 68 19,333 701380 .957 .831 .169

256 175.13 104 18,213 998011 .950 .829 .171 298.57 61 18,213 587270 .774 .780 .220

257 -- -- -- -- -- -- -- -- -- -- -- -- -- --

258 778.60 25 19,465 314435 2.532 .994 .006 1145.00 17 19,465 207297 1.806 .965 .035

259 410.82 11 4,519 23635 -.282 .389 .389 753.17 6 4,519 15148 .498 .691 .309

260 265.81 83 22,062 863542 -.897 .185 .185 565.69 39 22,062 402271 -.702 .241 .241

261 487.00 3 1,461 1583 -.833 .202 .202 1461.00 1 1,461 222 -1.206 .114 .114

262 291.83 23 6,712 71100 -.655 .256 .256 559.33 12 6,712 33301 -1.039 .150 .150

263 9269.00 2 18,538 20505 .260 .603 .397 9269.00 2 18,538 20505 .260 .603 .397

264 216.38 55 11,901 371327 1.729 .958 .042 276.77 43 11,901 301718 2.035 .979 .021

265 201.26 98 19,723 1009122 .758 .776 .224 358.60 55 19,723 585110 1.012 .844 .156

266 100.30 33 3,310 63218 1.567 .941 .059 174.21 19 3,310 36233 1.150 .875 .125

267 244.40 149 36,415 3175375 3.604 1.000 0 423.43 86 36,415 1810004 2.505 .994 .006

268 158.83 23 3,653 48935 1.369 .915 .085 260.93 14 3,653 26051 .122 .548 .452

269 -- -- -- -- -- -- -- -- -- -- -- -- -- --

270 232.03 61 14,154 424107 -.238 .406 .406 337.00 42 14,154 286378 -.410 .341 .341

271 -- -- -- -- -- -- -- -- -- -- -- -- -- --

272 -- -- -- -- -- -- -- -- -- -- -- -- -- --

273 324.18 98 31,770 1538862 -.197 .422 .422 588.33 54 31,770 817089 -.604 .273 .273

274 344.94 33 11,383 226468 2.047 .980 .020 569.15 20 11,383 143371 2.010 .978 .022

275 300.38 8 2,403 7473 -1.090 .138 .138 600.75 4 2,403 4741 -.047 .481 .481

276 1291.40 5 6,457 16273 .031 .513 .487 2152.33 3 6,457 7665 -.626 .266 .266

277 224.20 5 1,121 2182 -.858 .196 .196 224.20 5 1,121 2182 -.858 .196 .196

278 215.27 55 11,840 324256 -.053 .479 .479 394.67 30 11,840 174972 -.140 .444 .444

279 -- -- -- -- -- -- -- -- -- -- -- -- -- --

280 867.63 19 16,485 186864 1.459 .928 .072 1648.50 10 16,485 104238 1.450 .926 .074

281 441.50 10 4,415 24042 .488 .687 .313 735.83 6 4,415 10237 -.964 .168 .168

282 335.25 4 1,341 3631 1.226 .890 .110 1341.00 1 1,341 319 -.908 .182 .182

283 313.15 62 19,415 618455 .376 .647 .354 554.71 35 19,415 359933 .608 .728 .272

284 297.97 32 9,535 172613 1.288 .901 .099 501.84 19 9,535 106037 1.288 .901 .099

285 161.07 202 32,536 3106669 -1.344 .089 .089 278.09 117 32,536 1802222 -0.996 .160 .160

286 622.82 60 37,369 1075139 -.550 .291 .291 1009.97 37 37,369 640889 -.769 .221 .221

287 456.50 4 1,826 5049 1.325 .907 .093 608.67 3 1,826 4083 1.472 .929 .071

288 439.40 30 13,182 196574 -.056 .478 .478 693.79 19 13,182 110448 -.891 .187 .187

Table 7. Summary of interoccurrence intervals for daily precipitation thresholds of 2.5 and 3.0 inches—Continued

Seq.

no.

Daily precipitation threshold of 2.5 inches and greater Daily precipitation threshold of 3.0 inches and greater

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue
176 Atlas of Interoccurrence Intervals for Selected Thresholds of Daily Precipitation in Texas 

289 1134.00 1 1,134 494 -.223 .412 .412 -- -- -- -- -- -- --

290 406.81 75 30,511 1260248 1.522 .936 .064 649.17 47 30,511 752241 .584 .720 .280

291 464.55 42 19,511 307747 -2.794 .003 .003 929.10 21 19,511 153316 -1.997 .023 .023

292 365.17 6 2,191 8620 1.321 .907 .093 438.20 5 2,191 8197 1.923 .973 .027

293 215.38 164 35,323 3067213 1.307 .904 .096 349.73 101 35,323 1934583 1.471 .929 .071

294 171.22 110 18,834 1096118 1.057 .855 .145 269.06 70 18,834 683733 .540 .705 .295

295 312.37 19 5,935 68267 1.591 .944 .056 539.55 11 5,935 36830 .737 .769 .231

296 173.65 99 17,191 877258 .533 .703 .297 286.52 60 17,191 485387 -.789 .215 .215

297 182.67 107 19,546 941909 -1.779 .038 .038 305.41 64 19,546 548731 -1.700 .045 .045

298 340.90 30 10,227 162381 .555 .711 .289 601.59 17 10,227 99680 1.048 .853 .148

299 -- -- -- -- -- -- -- -- -- -- -- -- -- --

300 1214.25 4 4,857 10918 .429 .666 .334 2428.50 2 4,857 5530 .339 .633 .367

301 1124.73 15 16,871 146430 1.055 .854 .146 2410.14 7 16,871 60252 .093 .537 .463

302 1930.90 10 19,309 117397 1.183 .882 .118 3218.17 6 19,309 71623 1.003 .842 .158

303 97.40 5 487 1443 .717 .763 .237 243.50 2 487 341 -.734 .231 .231

304 248.03 101 25,051 1249117 -.220 .413 .413 431.91 58 25,051 758235 .577 .718 .282

305 129.50 12 1,554 9045 -.180 .429 .429 172.67 9 1,554 8137 .850 .802 .198

306 149.42 249 37,205 4847599 1.272 .898 .102 246.39 151 37,205 3015652 1.566 .941 .059

307 621.35 34 21,126 403358 1.243 .893 .107 1408.40 15 21,126 204288 1.941 .974 .026

308 195.30 91 17,772 828420 .405 .657 .343 286.65 62 17,772 557044 .151 .560 .440

309 583.50 2 1,167 1542 .787 .784 .216 1167.00 1 1,167 1150 1.682 .954 .046

310 310.30 10 3,103 14367 -.405 .343 .343 620.60 5 3,103 5884 -.935 .175 .175

311 1902.00 2 3,804 6837 1.953 .975 .025 3804.00 1 3,804 3603 1.549 .939 .061

312 268.51 69 18,527 735645 2.171 .985 .015 451.88 41 18,527 400160 .594 .724 .276

313 308.13 8 2,465 9274 -.291 .385 .385 616.25 4 2,465 5711 .549 .708 .292

314 377.00 3 1,131 2061 .645 .740 .260 565.50 2 1,131 1475 .745 .772 .228

315 140.48 133 18,684 1414525 2.766 .997 .003 252.49 74 18,684 833374 3.062 .999 .001

316 659.67 3 1,979 2926 -.043 .483 .483 659.67 3 1,979 2926 -.043 .483 .483

317 542.33 3 1,627 1559 -1.084 .139 .139 813.50 2 1,627 544 -1.631 .052 .052

318 611.04 27 16,498 193587 -1.177 .120 .120 1499.82 11 16,498 67244 -1.487 .068 .068

319 311.50 12 3,738 18982 -.922 .178 .178 934.50 4 3,738 3968 -1.626 .052 .052

320 -- -- -- -- -- -- -- -- -- -- -- -- -- --

321 227.84 91 20,733 1016513 1.281 .900 .100 431.94 48 20,733 526208 .690 .755 .245

322 227.96 55 12,538 364715 .742 .771 .229 358.23 35 12,538 215971 -.161 .436 .436

323 315.53 17 5,364 47686 .328 .628 .372 536.40 10 5,364 30409 .733 .768 .232

324 277.21 114 31,602 1994650 1.985 .976 .024 464.74 68 31,602 1241557 2.221 .987 .013

325 532.38 8 4,259 13758 -.943 .173 .173 4259.00 1 4,259 3398 1.032 .849 .151

326 158.34 41 6,492 137607 .377 .647 .353 240.44 27 6,492 93094 .560 .712 .288

327 369.36 22 8,126 71363 -1.638 .051 .051 580.43 14 8,126 45100 -1.342 .090 .090

328 975.00 1 975 354 -.474 .318 .318 -- -- -- -- -- -- --

329 99.71 116 11,566 632474 -1.067 .143 .143 156.30 74 11,566 421256 -.233 .408 .408

330 174.77 209 36,526 3814930 -.013 .495 .495 341.36 107 36,526 2097928 1.318 .906 .094

331 418.63 16 6,698 66224 1.634 .949 .051 669.80 10 6,698 41041 1.235 .892 .108

332 370.71 86 31,881 1388241 .203 .581 .419 650.63 49 31,881 855284 1.152 .875 .125

333 214.36 100 21,436 1060448 -0.184 .427 .427 345.74 62 21,436 615031 -1.016 .155 .155

334 1187.85 13 15,442 128214 1.732 .958 .042 1715.78 9 15,442 80253 .805 .789 .211

335 1169.42 19 22,219 190289 -.744 .229 .229 4443.80 5 22,219 43507 -.840 .201 .201

336 414.00 5 2,070 4539 -.476 .317 .317 1035.00 2 2,070 1902 -.199 .421 .421

Table 7. Summary of interoccurrence intervals for daily precipitation thresholds of 2.5 and 3.0 inches—Continued

Seq.

no.

Daily precipitation threshold of 2.5 inches and greater Daily precipitation threshold of 3.0 inches and greater

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue
Table 7 177

337 379.66 29 11,010 160392 .044 .517 .483 734.00 15 11,010 79466 -.253 .400 .400

338 444.39 13 5,777 43331 .961 .832 .168 825.29 7 5,777 24847 1.049 .853 .147

339 161.97 30 4,859 79732 .891 .814 .186 303.69 16 4,859 45648 1.208 .886 .114

340 195.00 32 6,240 99124 -.070 .472 .472 367.06 17 6,240 53090 .007 .503 .497

341 608.56 16 9,737 88172 .914 .820 .180 973.70 10 9,737 54941 .704 .759 .241

342 683.33 6 4,100 17989 1.962 .975 .025 820.00 5 4,100 13889 1.375 .915 .085

343 211.70 60 12,702 386193 .181 .572 .428 362.91 35 12,702 205412 -.778 .218 .218

344 235.81 146 34,428 2789631 2.302 .989 .011 405.04 85 34,428 1618296 1.693 .955 .045

345 121.25 4 485 988 .064 .526 .474 161.67 3 485 678 -.204 .419 .419

346 828.00 26 21,528 226848 -1.673 .047 .047 1794.00 12 21,528 99742 -1.367 .086 .086

347 1192.00 1 1,192 74 -1.517 .065 .065 1192.00 1 1,192 74 -1.517 .065 .065

348 587.68 19 11,166 124730 1.328 .908 .092 1395.75 8 11,166 53422 .961 .832 .168

349 429.27 26 11,161 154872 .595 .724 .276 744.07 15 11,161 87370 .294 .615 .385

350 512.42 55 28,183 792847 .295 .616 .384 805.23 35 28,183 524250 .645 .741 .259

351 386.50 10 3,865 21182 .526 .701 .299 966.25 4 3,865 8292 .252 .599 .401

352 1062.00 1 1,062 909 1.233 .891 .109 1062.00 1 1,062 909 1.233 .891 .109

353 191.59 17 3,257 28089 .104 .542 .458 814.25 4 3,257 10068 1.890 .971 .029

354 286.50 24 6,876 98615 1.656 .951 .049 528.92 13 6,876 46830 .299 .617 .383

355 279.25 40 11,170 213835 -.469 .320 .320 507.73 22 11,170 117533 -.353 .362 .362

356 328.38 109 35,793 1864696 -.797 .213 .213 586.77 61 35,793 991458 -1.242 .107 .107

357 478.59 66 31,587 1068387 .351 .637 .363 957.18 33 31,587 508714 -.238 .406 .406

358 449.62 42 18,884 414950 .520 .699 .301 993.90 19 18,884 195339 .671 .749 .251

359 1110.00 2 2,220 3600 1.523 .936 .064 2220.00 1 2,220 2046 1.461 .928 .072

360 362.00 2 724 828 .352 .638 .362 724.00 1 724 110 -1.206 .114 .114

361 -- -- -- -- -- -- -- -- -- -- -- -- -- --

362 175.45 121 21,229 1317190 .487 .687 .313 294.85 72 21,229 874019 2.111 .983 .017

363 136.75 16 2,188 16740 -.302 .381 .381 218.80 10 2,188 9646 -.648 .259 .259

364 136.97 70 9,588 324835 -.464 .321 .321 228.29 42 9,588 170266 -1.733 .042 .042

365 178.24 125 22,280 1364069 -.395 .346 .346 289.35 77 22,280 883044 .448 .673 .327

366 126.25 20 2,525 22675 -.790 .215 .215 132.90 19 2,525 21708 -.718 .237 .237

367 164.90 70 11,543 421646 .633 .737 .263 295.97 39 11,543 222622 -.119 .453 .453

368 366.35 23 8,426 92696 -.360 .359 .359 702.17 12 8,426 38233 -1.463 .072 .072

369 -- -- -- -- -- -- -- -- -- -- -- -- -- --

370 6537.00 1 6,537 2459 -.429 .334 .334 -- -- -- -- -- -- --

371 -- -- -- -- -- -- -- -- -- -- -- -- -- --

372 543.73 15 8,156 75519 1.574 .942 .058 815.60 10 8,156 46447 .761 .777 .223

373 -- -- -- -- -- -- -- -- -- -- -- -- -- --

374 874.00 1 874 828 1.550 .939 .061 -- -- -- -- -- -- --

375 510.52 21 10,721 99856 -.897 .185 .185 974.64 11 10,721 37456 -2.096 .018 .018

376 970.00 3 2,910 6164 1.236 .892 .108 970.00 3 2,910 6164 1.236 .892 .108

377 342.45 53 18,150 501616 .541 .706 .294 567.19 32 18,150 292945 .086 .534 .466

378 290.80 50 14,540 367334 .129 .551 .449 469.03 31 14,540 236531 .478 .684 .317

379 -- -- -- -- -- -- -- -- -- -- -- -- -- --

380 357.00 4 1,428 3424 .689 .754 .246 1428.00 1 1,428 1176 1.121 .869 .131

381 159.65 119 18,998 1267685 2.295 .989 .011 279.38 68 18,998 685020 0.864 .806 .194

382 98.67 3 296 305 -.939 .174 .174 -- -- -- -- -- -- --

383 345.21 94 32,450 1586563 .676 .750 .250 550.00 59 32,450 976829 .272 .607 .393

384 388.95 21 8,168 79589 -.572 .284 .284 628.31 13 8,168 49253 -.452 .326 .326

Table 7. Summary of interoccurrence intervals for daily precipitation thresholds of 2.5 and 3.0 inches—Continued

Seq.

no.

Daily precipitation threshold of 2.5 inches and greater Daily precipitation threshold of 3.0 inches and greater

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue
178 Atlas of Interoccurrence Intervals for Selected Thresholds of Daily Precipitation in Texas 

385 197.95 87 17,222 691271 -1.248 .106 .106 344.44 50 17,222 379027 -1.466 .071 .071

386 -- -- -- -- -- -- -- -- -- -- -- -- -- --

387 416.20 5 2,081 3648 -1.157 .124 .124 693.67 3 2,081 2765 -.343 .366 .366

388 308.00 8 2,464 6914 -1.462 .072 .072 1232.00 2 2,464 924 -1.531 .063 .063

389 363.00 1 363 331 1.427 .923 .077 363.00 1 363 331 1.427 .923 .077

390 133.41 131 17,476 1109857 -.603 .273 .273 196.36 89 17,476 714727 -1.323 .093 .093

391 354.93 45 15,972 359033 -.011 .496 .496 591.56 27 15,972 223791 .341 .633 .367

392 206.80 5 1,034 2132 -.679 .249 .249 258.50 4 1,034 1657 -.689 .246 .246

393 3531.33 3 10,594 11146 -.896 .185 .185 5297.00 2 10,594 11045 .104 .542 .458

394 -- -- -- -- -- -- -- -- -- -- -- -- -- --

395 222.32 41 9,115 196236 .557 .711 .289 536.18 17 9,115 65118 -1.139 .127 .127

396 205.17 96 19,696 958500 .235 .593 .407 364.74 54 19,696 588410 1.355 .912 .088

397 459.39 31 14,241 226970 .272 .607 .393 1017.21 14 14,241 97840 -.120 .452 .452

398 310.27 109 33,819 1819563 -.231 .409 .409 490.13 69 33,819 1189219 .277 .609 .391

399 265.11 74 19,618 707964 -.368 .357 .357 456.23 43 19,618 422078 .008 .503 .497

400 164.71 117 19,271 1160529 .551 .709 .291 296.48 65 19,271 642067 .351 .637 .363

401 1155.80 5 5,779 12958 -.399 .345 .345 1444.75 4 5,779 7742 -1.144 .126 .126

402 121.50 2 243 263 .202 .580 .420 243.00 1 243 24 -1.390 .082 .082

403 221.89 61 13,535 436144 .764 .778 .222 347.05 39 13,535 271205 .298 .617 .383

404 216.95 95 20,610 984084 .088 .535 .465 412.20 50 20,610 506025 -.219 .413 .413

405 371.38 32 11,884 213317 1.194 .884 .116 625.47 19 11,884 126044 .879 .810 .190

406 258.16 84 21,685 972961 1.084 .861 .139 409.15 53 21,685 643357 1.508 .934 .066

407 370.80 10 3,708 20985 .722 .765 .235 618.00 6 3,708 12357 .470 .681 .319

408 209.46 163 34,142 2820825 .304 .619 .381 371.11 92 34,142 1573816 .035 .514 .486

409 1216.00 1 1,216 423 -.527 .299 .299 -- -- -- -- -- -- --

410 236.03 61 14,398 449914 .332 .630 .370 378.90 38 14,398 272293 -.050 .480 .480

411 562.97 34 19,141 406526 2.518 .994 .006 1472.39 13 19,141 152808 1.425 .923 .077

412 272.49 51 13,897 428444 2.585 .995 .005 421.12 33 13,897 282503 2.309 .990 .010

413 310.95 97 30,162 1477100 .166 .566 .434 591.41 51 30,162 756639 -.201 .420 .420

414 163.00 21 3,423 36173 .051 .520 .480 213.94 16 3,423 28681 .328 .629 .371

415 693.23 31 21,490 320582 -.362 .359 .359 1074.50 20 21,490 213551 -.049 .481 .481

416 716.74 27 19,352 234264 -.930 .176 .176 1488.62 13 19,352 125425 -.018 .493 .493

417 438.86 7 3,072 16364 2.392 .992 .008 512.00 6 3,072 13789 2.105 .982 .018

418 958.65 26 24,925 318745 -.144 .443 .443 2265.91 11 24,925 127957 -.383 .351 .351

419 248.99 91 22,658 924306 -1.709 .044 .044 419.59 54 22,658 530869 -1.683 .046 .046

420 598.06 32 19,138 379722 2.352 .991 .009 1125.77 17 19,138 184154 .943 .827 .173

421 3465.67 9 31,191 147592 .268 .606 .394 4455.86 7 31,191 111061 .079 .532 .468

422 1931.50 6 11,589 24648 -1.235 .109 .109 2317.80 5 11,589 17234 -1.569 .058 .058

423 527.09 22 11,596 131146 .229 .590 .410 892.00 13 11,596 65108 -.851 .198 .198

424 -- -- -- -- -- -- -- -- -- -- -- -- -- --

425 1417.47 15 21,262 157992 -.062 .475 .475 3037.43 7 21,262 94005 1.206 .886 .114

426 992.61 18 17,867 146276 -.664 .253 .253 2233.38 8 17,867 63246 -.564 .287 .287

427 -- -- -- -- -- -- -- -- -- -- -- -- -- --

428 282.24 17 4,798 46141 .938 .826 .174 436.18 11 4,798 27912 .332 .630 .370

429 541.20 10 5,412 20392 -1.350 .089 .089 1353.00 4 5,412 4867 -1.907 .028 .028

430 278.59 32 8,915 160305 1.213 .887 .113 685.77 13 8,915 66888 .964 .832 .168

431 550.86 7 3,856 11573 -.653 .257 .257 771.20 5 3,856 7556 -.837 .201 .201

432 131.64 66 8,688 225229 -3.017 .001 .001 228.63 38 8,688 127682 -2.418 .008 .008

Table 7. Summary of interoccurrence intervals for daily precipitation thresholds of 2.5 and 3.0 inches—Continued

Seq.

no.

Daily precipitation threshold of 2.5 inches and greater Daily precipitation threshold of 3.0 inches and greater

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue
Table 7 179

433 291.00 94 27,354 1243528 -.550 .291 .291 463.63 59 27,354 683748 -2.031 .021 .021

434 230.46 59 13,597 395077 -.200 .421 .421 543.88 25 13,597 165898 -.207 .418 .418

435 147.57 7 1,033 5323 2.164 .985 .015 258.25 4 1,033 3498 2.401 .992 .008

436 309.09 94 29,054 1478357 1.387 .917 .083 468.61 62 29,054 968007 1.020 .846 .154

437 109.62 231 25,322 2960914 .326 .628 .372 190.39 133 25,322 1668013 -.189 .425 .425

438 230.51 81 18,671 771761 .321 .626 .374 366.10 51 18,671 464415 -.304 .381 .381

439 371.09 22 8,164 82502 -.661 .255 .255 680.33 12 8,164 47511 -.180 .428 .428

440 273.59 34 9,302 169138 .703 .759 .241 372.08 25 9,302 113189 -.230 .409 .409

441 1483.31 16 23,733 198349 .310 .622 .378 3955.50 6 23,733 69689 -.090 .464 .464

442 196.45 65 12,769 481780 2.247 .988 .012 327.41 39 12,769 283853 1.514 .935 .065

443 295.16 44 12,987 271920 -.555 .290 .290 418.94 31 12,987 191941 -.448 .327 .327

444 403.25 4 1,613 4637 1.515 .935 .065 537.67 3 1,613 3070 .807 .790 .210

445 660.00 29 19,140 301219 .796 .787 .213 1276.00 15 19,140 148665 .239 .594 .406

446 392.33 3 1,177 2912 1.948 .974 .026 588.50 2 1,177 2147 2.019 .978 .022

447 573.45 40 22,938 441064 -.423 .336 .336 1092.29 21 22,938 227427 -.442 .329 .329

448 244.40 129 31,527 1782422 -2.429 .008 .008 404.19 78 31,527 1094310 -1.683 .046 .046

449 166.16 32 5,317 74905 -1.171 .121 .121 241.68 22 5,317 46629 -1.647 .050 .050

450 171.11 120 20,533 1244170 .188 .574 .426 266.66 77 20,533 813650 .445 .672 .328

451 185.40 30 5,562 82209 -.139 .445 .445 231.75 24 5,562 70064 .422 .664 .336

452 304.00 1 304 267 1.310 .905 .095 304.00 1 304 267 1.310 .905 .095

453 2103.00 1 2,103 1405 .582 .720 .280 -- -- -- -- -- -- --

454 756.76 42 31,784 650525 -.285 .388 .388 1222.46 26 31,784 364338 -1.044 .148 .148

455 887.00 1 887 525 .318 .625 .375 -- -- -- -- -- -- --

456 -- -- -- -- -- -- -- -- -- -- -- -- -- --

457 113.67 3 341 640 .754 .774 .226 -- -- -- -- -- -- --

458 151.78 41 6,223 121402 -.536 .296 .296 259.29 24 6,223 63769 -1.239 .108 .108

459 160.14 7 1,121 3787 -.159 .437 .437 224.20 5 1,121 3024 .306 .620 .380

460 228.90 143 32,732 2245601 -.838 .201 .201 404.10 81 32,732 1236357 -1.050 .147 .147

461 282.43 109 30,785 1627288 -.544 .293 .293 446.16 69 30,785 997168 -.879 .190 .190

462 249.86 71 17,740 614815 -.347 .364 .364 506.86 35 17,740 261964 -1.600 .055 .055

463 207.69 36 7,477 134756 .013 .505 .495 373.85 20 7,477 72826 -.201 .420 .420

464 187.50 120 22,500 1331544 -.259 .398 .398 330.88 68 22,500 722863 -.787 .216 .216

465 393.20 5 1,966 6395 1.166 .878 .122 983.00 2 1,966 2914 1.181 .881 .119

466 178.46 147 26,233 1974177 .502 .692 .308 305.04 86 26,233 1257357 1.842 .967 .033

467 2765.75 4 11,063 23562 .225 .589 .411 5531.50 2 11,063 13456 .530 .702 .298

468 165.50 6 993 1778 -1.710 .044 .044 198.60 5 993 904 -2.463 .007 .007

469 188.87 52 9,821 262553 .353 .638 .362 327.37 30 9,821 170154 1.471 .929 .071

470 -- -- -- -- -- -- -- -- -- -- -- -- -- --

471 252.60 53 13,388 392891 1.355 .912 .088 478.14 28 13,388 208577 1.034 .849 .151

472 146.61 23 3,372 49348 2.264 .988 .012 210.75 16 3,372 38648 2.998 .999 .001

473 240.33 80 19,226 811068 .847 .801 .199 417.96 46 19,226 453254 .294 .616 .384

474 370.24 68 25,176 855911 -.001 .500 .500 645.54 39 25,176 519920 .639 .738 .262

475 194.87 164 31,959 2834839 1.813 .965 .035 301.50 106 31,959 1866767 1.821 .966 .034

476 175.36 104 18,237 934927 -.250 .401 .401 260.53 70 18,237 675038 .834 .798 .202

477 262.56 16 4,201 43014 1.939 .974 .026 381.91 11 4,201 26939 0.953 .830 .170

478 221.76 104 23,063 1172851 -.389 .349 .349 427.09 54 23,063 632650 .203 .581 .419

479 119.47 15 1,792 11157 -1.140 .127 .127 224.00 8 1,792 6765 -.275 .391 .391

480 177.63 32 5,684 86185 -.513 .304 .304 315.78 18 5,684 58220 1.015 .845 .155

Table 7. Summary of interoccurrence intervals for daily precipitation thresholds of 2.5 and 3.0 inches—Continued

Seq.

no.

Daily precipitation threshold of 2.5 inches and greater Daily precipitation threshold of 3.0 inches and greater

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue
180 Atlas of Interoccurrence Intervals for Selected Thresholds of Daily Precipitation in Texas 

481 105.42 120 12,650 905938 3.673 1.000 0 164.29 77 12,650 556385 2.165 .985 .015

482 247.27 15 3,709 22441 -1.297 .097 .097 370.90 10 3,709 10148 -2.480 .007 .007

483 453.43 7 3,174 9714 -.576 .283 .283 793.50 4 3,174 5020 -.725 .234 .234

484 182.40 15 2,736 19246 -.417 .339 .339 248.73 11 2,736 13685 -.520 .301 .301

485 848.00 1 848 200 -.915 .180 .180 848.00 1 848 200 -.915 .180 .180

486 409.17 85 34,779 1637199 1.719 .957 .043 772.87 45 34,779 872617 1.338 .909 .091

487 299.54 35 10,484 163705 -1.104 .135 .135 499.24 21 10,484 89190 -1.506 .066 .066

488 1480.95 19 28,138 226901 -1.141 .127 .127 3126.44 9 28,138 114129 -.513 .304 .304

489 270.40 43 11,627 266036 .730 .767 .233 387.57 30 11,627 193162 1.020 .846 .154

490 325.08 24 7,802 125017 2.845 .998 .002 780.20 10 7,802 50333 1.590 .944 .056

491 202.70 63 12,770 413105 .371 .645 .355 364.86 35 12,770 221198 -.104 .458 .458

492 272.70 92 25,088 1131296 -.328 .372 .372 501.76 50 25,088 568979 -1.137 .128 .128

493 197.02 181 35,661 3386237 1.147 .874 .126 353.08 101 35,661 1875666 .723 .765 .235

494 163.96 26 4,263 61561 .979 .836 .164 327.92 13 4,263 31748 .910 .819 .181

495 147.42 138 20,344 1499024 1.381 .916 .084 251.16 81 20,344 852250 .536 .704 .296

496 862.28 25 21,557 192756 -2.465 .007 .007 1658.23 13 21,557 96266 -1.955 .025 .025

497 -- -- -- -- -- -- -- -- -- -- -- -- -- --

498 211.88 90 19,069 918608 1.159 .877 .123 353.13 54 19,069 536464 .534 .703 .297

499 493.00 36 17,748 332738 .432 .667 .333 806.73 22 17,748 208233 .541 .706 .294

500 231.20 5 1,156 4075 1.588 .944 .056 231.20 5 1,156 4075 1.588 .944 .056

501 255.60 20 5,112 45139 -.906 .182 .182 393.23 13 5,112 34192 .181 .572 .428

502 188.70 162 30,570 2893298 3.714 1.000 0 339.67 90 30,570 1641821 3.179 .999 .001

503 556.36 11 6,120 35060 .239 .594 .406 874.29 7 6,120 23750 .499 .691 .309

504 1227.67 3 3,683 7780 1.225 .890 .110 1227.67 3 3,683 7780 1.225 .890 .110

505 -- -- -- -- -- -- -- -- -- -- -- -- -- --

506 194.80 192 37,401 3962934 2.490 .994 .006 328.08 114 37,401 2292821 1.396 .919 .081

507 107.39 13 1,396 9955 .606 .728 .272 279.20 5 1,396 3742 .280 .610 .390

508 397.05 40 15,882 360670 1.484 .931 .069 661.75 24 15,882 223709 1.475 .930 .070

509 520.80 49 25,519 618035 -.139 .445 .445 850.63 30 25,519 359953 -.566 .286 .286

510 -- -- -- -- -- -- -- -- -- -- -- -- -- --

511 167.49 111 18,591 1165695 2.368 .991 .009 331.98 56 18,591 614811 2.347 .991 .009

512 264.98 119 31,532 1899486 .235 .593 .407 450.46 70 31,532 1108722 .067 .527 .473

513 361.12 59 21,306 707225 1.666 .952 .048 560.68 38 21,306 467074 1.642 .950 .050

514 -- -- -- -- -- -- -- -- -- -- -- -- -- --

515 1340.33 12 16,084 115729 1.195 .884 .116 2680.67 6 16,084 64498 1.429 .923 .077

516 -- -- -- -- -- -- -- -- -- -- -- -- -- --

517 1304.00 15 19,560 207871 2.797 .997 .003 3912.00 5 19,560 75935 2.141 .984 .016

518 582.35 63 36,688 1018146 -1.636 .051 .051 940.72 39 36,688 652451 -.952 .171 .171

519 643.00 12 7,716 52143 .758 .776 .224 1929.00 4 7,716 16427 .223 .588 .412

520 670.00 1 670 641 1.582 .943 .057 -- -- -- -- -- -- --

521 181.86 98 17,822 956856 1.641 .950 .050 371.29 48 17,822 447418 .552 .710 .290

522 389.58 19 7,402 64859 -.586 .279 .279 616.83 12 7,402 40073 -.586 .279 .279

523 543.43 7 3,804 14234 .317 .624 .376 634.00 6 3,804 12642 .457 .676 .324

524 -- -- -- -- -- -- -- -- -- -- -- -- -- --

525 -- -- -- -- -- -- -- -- -- -- -- -- -- --

526 346.39 94 32,561 1583688 0.585 .721 .279 551.88 59 32,561 983596 0.319 .625 .375

527 167.15 52 8,692 229133 .174 .569 .431 310.43 28 8,692 120395 -.097 .461 .461

528 108.86 29 3,157 47473 .346 .635 .365 185.71 17 3,157 25051 -.475 .318 .318

Table 7. Summary of interoccurrence intervals for daily precipitation thresholds of 2.5 and 3.0 inches—Continued

Seq.

no.

Daily precipitation threshold of 2.5 inches and greater Daily precipitation threshold of 3.0 inches and greater

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue
Table 7 181

529 186.82 62 11,583 372903 .525 .700 .300 297.00 39 11,583 241729 .760 .776 .224

530 180.55 189 34,124 3179008 -.338 .368 .368 331.30 103 34,124 1773946 .166 .566 .434

531 212.10 30 6,363 102445 .696 .757 .243 353.50 18 6,363 68600 1.454 .927 .073

532 400.62 90 36,056 1710638 .892 .814 .186 680.30 53 36,056 1015890 .797 .787 .213

533 919.89 28 25,757 372170 .294 .616 .384 2146.42 12 25,757 170491 .619 .732 .268

534 493.00 2 986 1601 1.528 .937 .063 493.00 2 986 1601 1.528 .937 .063

535 262.21 160 41,954 3293077 -.413 .340 .340 466.16 90 41,954 1876573 -.099 .461 .461

536 -- -- -- -- -- -- -- -- -- -- -- -- -- --

537 354.04 90 31,864 1514423 .923 .822 .178 579.35 55 31,864 980385 1.526 .937 .063

538 572.50 4 2,290 4406 -.132 .448 .448 1145.00 2 2,290 2136 -.165 .435 .435

539 704.50 28 19,726 311245 1.164 .878 .122 1232.88 16 19,726 187568 1.307 .904 .096

540 333.20 5 1,666 5263 1.021 .846 .154 555.33 3 1,666 2853 .425 .665 .335

541 245.00 143 35,035 2529622 .204 .581 .419 412.18 85 35,035 1615821 1.360 .913 .087

542 197.33 6 1,184 2935 -.737 .231 .231 394.67 3 1,184 1634 -.240 .405 .405

543 1046.63 8 8,373 31105 -.349 .363 .363 1674.60 5 8,373 21600 .124 .549 .451

544 250.68 117 29,330 1636952 -.861 .195 .195 437.76 67 29,330 966982 -.225 .411 .411

545 524.81 16 8,397 51548 -1.612 .054 .054 645.92 13 8,397 42443 -1.389 .082 .082

546 159.41 197 31,403 3270830 1.396 .919 .081 268.40 117 31,403 1883998 .479 .684 .316

547 339.42 52 17,650 463334 .121 .548 .452 767.39 23 17,650 229759 1.096 .863 .137

548 154.26 85 13,112 549594 -.220 .413 .413 312.19 42 13,112 238143 -1.517 .065 .065

549 -- -- -- -- -- -- -- -- -- -- -- -- -- --

550 209.50 4 838 1825 .308 .621 .379 279.33 3 838 1342 .203 .580 .420

551 156.74 35 5,486 97418 .151 .560 .440 288.74 19 5,486 58361 .905 .817 .183

552 167.24 117 19,567 1249669 1.719 .957 .043 275.59 71 19,567 777566 1.743 .959 .041

553 -- -- -- -- -- -- -- -- -- -- -- -- -- --

554 167.62 71 11,901 398903 -.815 .208 .208 276.77 43 11,901 252178 -.164 .435 .435

555 -- -- -- -- -- -- -- -- -- -- -- -- -- --

556 119.01 168 19,994 1689794 .138 .555 .445 197.96 101 19,994 1055271 .786 .784 .216

557 -- -- -- -- -- -- -- -- -- -- -- -- -- --

558 101.38 21 2,129 22349 -.002 .499 .499 141.93 15 2,129 16692 .304 .620 .380

559 584.00 1 584 122 -1.008 .157 .157 584.00 1 584 122 -1.008 .157 .157

560 -- -- -- -- -- -- -- -- -- -- -- -- -- --

561 144.65 123 17,792 1317844 3.926 1.000 0 199.91 89 17,792 950396 3.274 .999 .001

562 137.94 150 20,691 1651326 1.360 .913 .087 213.31 97 20,691 1045524 .714 .762 .238

563 149.50 113 16,893 1031994 1.496 .933 .067 244.83 69 16,893 621461 .954 .830 .170

564 160.84 118 18,979 1236431 1.960 .975 .025 279.10 68 18,979 731327 1.904 .972 .028

565 92.40 53 4,897 155307 2.481 .993 .007 139.91 35 4,897 98900 1.579 .943 .057

566 122.80 122 14,981 935640 .456 .676 .324 187.26 80 14,981 629811 .790 .785 .215

567 274.75 32 8,792 176482 2.494 .994 .006 399.64 22 8,792 124070 2.298 .989 .011

568 163.04 97 15,815 834257 1.495 .933 .067 292.87 54 15,815 491474 1.922 .973 .027

569 158.93 58 9,218 244577 -1.122 .131 .131 263.37 35 9,218 148674 -.803 .211 .211

570 117.32 31 3,637 56310 -.011 .496 .496 158.13 23 3,637 45071 .645 .740 .260

571 140.57 129 18,133 1388712 3.686 1.000 0 235.49 77 18,133 798074 2.176 .985 .015

572 266.02 48 12,769 327302 .816 .793 .207 425.63 30 12,769 210117 .920 .821 .179

573 420.08 12 5,041 28955 -0.256 .399 .399 560.11 9 5,041 22819 0.031 .512 .488

574 131.33 85 11,163 516347 1.411 .921 .079 195.84 57 11,163 340841 .933 .825 .176

575 372.36 47 17,501 444649 .964 .832 .168 760.91 23 17,501 190757 -.434 .332 .332

576 258.36 14 3,617 27321 .512 .696 .304 401.89 9 3,617 17807 .489 .687 .313

Table 7. Summary of interoccurrence intervals for daily precipitation thresholds of 2.5 and 3.0 inches—Continued

Seq.

no.

Daily precipitation threshold of 2.5 inches and greater Daily precipitation threshold of 3.0 inches and greater

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue
182 Atlas of Interoccurrence Intervals for Selected Thresholds of Daily Precipitation in Texas 

577 299.48 62 18,568 622871 1.120 .869 .131 488.63 38 18,568 447594 2.869 .998 .002

578 178.27 113 20,145 1155342 .277 .609 .391 305.23 66 20,145 675573 .228 .590 .410

579 281.80 50 14,090 326818 -.884 .188 .188 469.67 30 14,090 187776 -1.058 .145 .145

580 -- -- -- -- -- -- -- -- -- -- -- -- -- --

581 139.29 17 2,368 20310 .065 .526 .474 197.33 12 2,368 14664 .193 .576 .424

582 240.20 77 18,495 798680 1.849 .968 .032 420.34 44 18,495 458655 1.462 .928 .072

583 1244.77 13 16,182 120699 .921 .821 .179 1798.00 9 16,182 89194 1.169 .879 .121

584 -- -- -- -- -- -- -- -- -- -- -- -- -- --

585 345.53 38 13,130 252461 .128 .551 .449 691.05 19 13,130 105878 -1.141 .127 .127

586 -- -- -- -- -- -- -- -- -- -- -- -- -- --

587 202.83 18 3,651 37112 .951 .829 .171 331.91 11 3,651 23203 .893 .814 .186

588 388.64 22 8,550 90207 -.332 .370 .370 570.00 15 8,550 54728 -.983 .163 .163

589 168.03 39 6,553 139764 1.014 .845 .155 262.12 25 6,553 91326 .995 .840 .160

590 185.00 2 370 500 .861 .805 .195 185.00 2 370 500 .861 .805 .195

591 192.26 19 3,653 36553 .402 .656 .344 304.42 12 3,653 22270 .096 .538 .462

592 334.49 66 22,076 766386 .732 .768 .232 668.97 33 22,076 371516 .198 .579 .421

593 189.20 82 15,514 674293 .942 .827 .173 330.09 47 15,514 417494 1.723 .958 .042

594 255.39 23 5,874 82807 1.876 .970 .030 419.57 14 5,874 46437 .838 .799 .201

595 341.70 27 9,226 101748 -1.648 .050 .050 542.71 17 9,226 60180 -1.661 .048 .048

596 279.46 92 25,710 1317948 1.900 .971 .029 514.20 50 25,710 608068 -.661 .254 .254

597 132.71 155 20,570 1896218 4.086 1.000 0 218.83 94 20,570 1179264 3.691 1.000 0

598 149.57 7 1,047 2458 -1.509 .066 .066 174.50 6 1,047 2360 -1.055 .146 .146

599 804.50 22 17,699 222645 1.167 .878 .122 1966.56 9 17,699 104431 1.617 .947 .053

600 217.02 90 19,532 854468 -.458 .324 .324 305.19 64 19,532 589014 -.798 .212 .212

601 187.90 172 32,319 2671262 -.884 .188 .188 310.76 104 32,319 1634736 -.482 .315 .315

602 183.08 84 15,379 661760 .389 .651 .349 341.76 45 15,379 325050 -.704 .241 .241

603 177.89 35 6,226 133699 2.327 .990 .010 270.70 23 6,226 84623 1.511 .935 .065

604 255.77 48 12,277 306501 .483 .685 .315 438.46 28 12,277 199218 1.458 .928 .072

605 477.69 13 6,210 48581 1.271 .898 .102 1035.00 6 6,210 18812 .041 .517 .483

606 376.14 14 5,266 44437 1.332 .909 .092 478.73 11 5,266 31987 .600 .726 .274

607 973.75 4 3,895 9116 .590 .722 .278 1947.50 2 3,895 6513 1.646 .950 .050

608 246.07 86 21,162 943321 .589 .722 .278 450.26 47 21,162 527893 .730 .767 .233

609 2895.00 1 2,895 2440 1.188 .882 .118 2895.00 1 2,895 2440 1.188 .882 .118

610 423.43 72 30,487 966796 -1.751 .040 .040 781.72 39 30,487 522805 -1.304 .096 .096

611 913.22 9 8,219 44097 .999 .841 .159 1643.80 5 8,219 28521 1.503 .934 .066

612 361.00 10 3,610 23968 1.796 .964 .036 601.67 6 3,610 15395 1.788 .963 .037

613 172.25 4 689 1003 -.943 .173 .173 689.00 1 689 200 -.727 .234 .234

614 479.14 7 3,354 7764 -1.552 .060 .060 559.00 6 3,354 5240 -2.033 .021 .021

615 -- -- -- -- -- -- -- -- -- -- -- -- -- --

616 156.50 12 1,878 9777 -.794 .214 .214 268.29 7 1,878 7060 .340 .633 .367

617 175.30 10 1,753 6434 -1.457 .073 .073 350.60 5 1,753 4652 .238 .594 .406

618 191.13 108 20,642 1237155 1.978 .976 .024 322.53 64 20,642 773229 2.364 .991 .009

619 265.82 107 28,443 1477962 -.515 .303 .303 482.09 59 28,443 827281 -.187 .426 .426

620 -- -- -- -- -- -- -- -- -- -- -- -- -- --

621 161.75 102 16,498 849254 0.163 .565 .435 294.61 56 16,498 420805 -1.154 .124 .124

622 206.77 175 36,185 3166373 .001 .501 .499 361.85 100 36,185 1790740 -.177 .430 .430

623 460.25 16 7,364 54593 -.508 .306 .306 669.46 11 7,364 41666 .165 .566 .434

624 149.54 13 1,944 11432 -.595 .276 .276 243.00 8 1,944 8049 .172 .568 .432

Table 7. Summary of interoccurrence intervals for daily precipitation thresholds of 2.5 and 3.0 inches—Continued

Seq.

no.

Daily precipitation threshold of 2.5 inches and greater Daily precipitation threshold of 3.0 inches and greater

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue
Table 7 183

625 237.14 42 9,960 227368 .977 .836 .164 355.71 28 9,960 148553 .599 .725 .275

626 251.79 43 10,827 225454 -.358 .360 .360 386.68 28 10,827 148865 -.164 .435 .435

627 5910.50 2 11,821 18539 1.392 .918 .082 -- -- -- -- -- -- --

628 2501.50 2 5,003 1908 -1.515 .065 .065 2501.50 2 5,003 1908 -1.515 .065 .065

629 300.59 88 26,452 1139410 -.342 .366 .366 448.34 59 26,452 824766 .758 .776 .224

630 242.02 41 9,923 177168 -1.431 .076 .076 413.46 24 9,923 101418 -1.258 .104 .104

631 231.79 47 10,894 272181 .750 .773 .227 330.12 33 10,894 171132 -.477 .317 .317

632 418.95 19 7,960 90596 1.495 .933 .067 884.44 9 7,960 50410 2.117 .983 .017

633 189.11 9 1,702 6818 -.571 .284 .284 283.67 6 1,702 5037 -.057 .477 .477

634 -- -- -- -- -- -- -- -- -- -- -- -- -- --

635 250.86 107 26,842 1490221 .676 .750 .250 400.63 67 26,842 959184 .946 .828 .172

636 112.12 185 20,742 1905762 -.158 .437 .437 209.52 99 20,742 1045131 .309 .621 .379

637 542.44 45 24,410 629690 1.702 .956 .044 1109.55 22 24,410 342450 2.237 .987 .013

638 585.00 19 11,115 113017 .531 .702 .298 1010.46 11 11,115 68967 .736 .769 .231

639 326.50 16 5,224 50313 1.413 .921 .079 1044.80 5 5,224 16545 1.034 .849 .151

640 112.79 52 5,865 161865 .768 .779 .221 183.28 32 5,865 105514 1.219 .889 .111

641 1196.00 1 1,196 1059 1.335 .909 .091 1196.00 1 1,196 1059 1.335 .909 .091

642 -- -- -- -- -- -- -- -- -- -- -- -- -- --

643 206.62 159 32,853 2580330 -.263 .396 .396 309.93 106 32,853 1653434 -.899 .184 .184

644 618.25 4 2,473 7246 1.611 .946 .054 824.33 3 2,473 5774 1.670 .952 .048

645 365.89 75 27,442 985565 -.634 .263 .263 560.04 49 27,442 661816 -.190 .425 .425

646 10357.50 2 20,715 21331 .073 .529 .471 20715.00 1 20,715 5666 -.785 .216 .216

647 181.40 5 907 2742 .811 .791 .209 907.00 1 907 782 1.255 .895 .105

648 273.29 7 1,913 6922 .155 .562 .438 478.25 4 1,913 3471 -.321 .374 .374

649 4085.00 2 8,170 5783 -.716 .237 .237 8170.00 1 8,170 2891 -.506 .306 .306

650 436.09 33 14,391 219972 -.732 .232 .232 757.42 19 14,391 140654 .218 .586 .414

651 700.50 4 2,802 8291 1.661 .952 .048 1401.00 2 2,802 4525 1.506 .934 .066

652 798.00 1 798 490 .395 .654 .346 -- -- -- -- -- -- --

653 361.00 3 1,083 1254 -.684 .247 .247 1083.00 1 1,083 233 -.987 .162 .162

654 796.23 13 10,351 87984 1.922 .973 .027 1725.17 6 10,351 43649 1.721 .957 .043

655 476.83 6 2,861 4779 -1.880 .030 .030 572.20 5 2,861 3932 -1.744 .041 .041

656 128.19 37 4,743 75922 -1.420 .078 .078 249.63 19 4,743 41400 -.613 .270 .270

657 552.14 21 11,595 115890 -.382 .351 .351 966.25 12 11,595 62197 -.636 .262 .262

658 337.00 17 5,729 43746 -.726 .234 .234 572.90 10 5,729 27811 -.160 .437 .437

659 277.60 10 2,776 12238 -.648 .259 .259 462.67 6 2,776 5111 -1.639 .051 .051

660 145.61 33 4,805 86145 .861 .805 .195 300.31 16 4,805 41411 .536 .704 .296

661 123.13 23 2,832 30195 -.605 .273 .273 202.29 14 2,832 23059 1.058 .855 .145

662 305.00 18 5,490 45952 -.514 .304 .304 549.00 10 5,490 24785 -.532 .297 .297

663 1087.40 30 32,622 528270 .755 .775 .225 1812.33 18 32,622 294658 .027 .511 .489

664 407.52 91 37,084 1620860 -.651 .258 .258 741.68 50 37,084 899510 -.365 .358 .358

665 941.30 20 18,826 188120 -.006 .498 .498 1448.15 13 18,826 106314 -.819 .206 .206

666 433.00 3 1,299 2362 .637 .738 .262 649.50 2 1,299 2131 1.569 .942 .058

667 402.62 34 13,689 173564 -2.567 .005 .005 622.23 22 13,689 99177 -2.773 .003 .003

668 517.40 15 7,761 46458 -1.354 .088 .088 970.13 8 7,761 28748 -.362 .359 .359

669 298.74 19 5,676 59187 0.737 .769 .231 516.00 11 5,676 29607 -0.296 .383 .383

670 424.25 20 8,485 74546 -.941 .174 .174 606.07 14 8,485 57706 -.184 .427 .427

671 226.47 83 18,797 894524 2.315 .990 .010 427.21 44 18,797 459953 1.290 .901 .099

672 429.87 45 19,344 447570 .329 .629 .371 690.86 28 19,344 290008 .650 .742 .258

Table 7. Summary of interoccurrence intervals for daily precipitation thresholds of 2.5 and 3.0 inches—Continued

Seq.

no.

Daily precipitation threshold of 2.5 inches and greater Daily precipitation threshold of 3.0 inches and greater

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue
184 Atlas of Interoccurrence Intervals for Selected Thresholds of Daily Precipitation in Texas 

673 609.00 9 5,481 27999 .703 .759 .241 609.00 9 5,481 27999 .703 .759 .241

674 198.67 9 1,788 7302 -.481 .315 .315 223.50 8 1,788 6943 -.143 .443 .443

675 240.82 11 2,649 11313 -1.284 .100 .100 441.50 6 2,649 7546 -.214 .415 .415

676 277.00 12 3,324 15045 -1.474 .070 .070 554.00 6 3,324 8369 -.682 .248 .248

677 856.04 24 20,545 254036 .258 .602 .398 1712.08 12 20,545 101314 -1.069 .143 .143

678 -- -- -- -- -- -- -- -- -- -- -- -- -- --

679 838.15 27 22,630 305087 -.012 .495 .495 1616.43 14 22,630 150465 -.325 .373 .373

680 436.00 10 4,360 23664 .468 .680 .320 726.67 6 4,360 15053 .640 .739 .261

681 419.00 2 838 472 -1.070 .142 .142 838.00 1 838 439 .083 .533 .467

682 339.47 15 5,092 39076 .156 .562 .438 848.67 6 5,092 19799 1.256 .895 .105

683 221.80 55 12,199 333214 -.087 .465 .465 381.22 32 12,199 176277 -.949 .171 .171

684 228.27 68 15,522 488562 -1.061 .145 .145 419.51 37 15,522 298069 .400 .656 .344

685 108.03 326 35,218 6194764 2.475 .993 .007 175.21 201 35,218 3808734 1.869 .969 .031

686 307.74 19 5,847 70153 1.985 .976 .024 487.25 12 5,847 41304 1.064 .856 .144

687 774.00 2 1,548 1411 -.217 .414 .414 1548.00 1 1,548 1285 1.144 .874 .126

688 160.25 28 4,487 78934 2.351 .991 .009 213.67 21 4,487 61691 2.456 .993 .007

689 196.63 30 5,899 93020 .486 .687 .313 393.27 15 5,899 45951 .259 .602 .398

690 154.65 81 12,527 497109 -.315 .377 .377 313.18 40 12,527 221819 -1.256 .105 .105

691 127.22 144 18,319 1521872 3.197 .999 .001 218.08 84 18,319 893719 2.565 .995 .005

692 284.73 66 18,792 708766 2.011 .978 .022 447.43 42 18,792 424791 .858 .804 .196

693 1197.69 16 19,163 144315 -.406 .342 .342 1742.09 11 19,163 94551 -.591 .277 .277

694 280.81 26 7,301 84137 -1.003 .158 .158 456.31 16 7,301 55460 -.350 .363 .363

695 1127.58 12 13,531 98975 1.315 .906 .094 2706.20 5 13,531 29142 -.537 .296 .296

696 854.80 15 12,822 62805 -2.327 .010 .010 1424.67 9 12,822 41702 -1.441 .075 .075

697 155.16 152 23,585 1790229 -.027 .489 .489 235.85 100 23,585 1163826 -.227 .410 .410

698 469.08 80 37,526 1461466 -.408 .342 .342 815.78 46 37,526 854495 -.117 .453 .453

699 395.75 4 1,583 2082 -1.186 .118 .118 527.67 3 1,583 1107 -1.601 .055 .055

700 216.07 91 19,662 929879 .651 .742 .258 370.98 53 19,662 585556 1.561 .941 .059

701 199.22 9 1,793 7595 -.305 .380 .380 224.13 8 1,793 7008 -.112 .455 .455

702 404.00 3 1,212 1198 -1.023 .153 .153 404.00 3 1,212 1198 -1.023 .153 .153

703 224.86 21 4,722 60619 1.767 .961 .039 363.23 13 4,722 35745 1.028 .848 .152

704 424.00 1 424 24 -1.536 .062 .062 -- -- -- -- -- -- --

705 217.68 59 12,843 402563 .832 .797 .203 428.10 30 12,843 204200 .569 .715 .285

706 213.57 168 35,879 3251254 1.769 .962 .038 348.34 103 35,879 2084175 2.249 .988 .012

707 157.76 59 9,308 293177 .901 .816 .184 310.27 30 9,308 143932 .293 .615 .385

708 850.68 19 16,163 174059 1.009 .843 .157 2309.00 7 16,163 72172 1.264 .897 .103

709 -- -- -- -- -- -- -- -- -- -- -- -- -- --

710 599.00 2 1,198 1033 -.337 .368 .368 1198.00 1 1,198 323 -.798 .212 .212

711 570.00 26 14,820 224391 1.455 .927 .073 1058.57 14 14,820 148464 2.794 .997 .003

712 447.00 3 1,341 1587 -.633 .263 .263 1341.00 1 1,341 714 .112 .545 .455

713 260.33 39 10,153 212531 .795 .787 .213 406.12 25 10,153 131913 .341 .634 .366

714 -- -- -- -- -- -- -- -- -- -- -- -- -- --

715 730.00 2 1,460 1412 -.081 .468 .468 1460.00 1 1,460 884 .365 .643 .357

716 2105.33 3 6,316 10600 .357 .639 .361 3158.00 2 6,316 5985 -.128 .449 .449

717 872.21 38 33,144 591142 -0.654 .256 .256 1841.33 18 33,144 296013 -0.056 .478 .478

718 172.13 40 6,885 142808 .406 .658 .342 299.35 23 6,885 92168 1.363 .914 .086

719 114.84 38 4,364 79672 -.418 .338 .338 189.74 23 4,364 48332 -.307 .379 .379

720 198.98 167 33,230 2806982 .260 .603 .397 307.69 108 33,230 1949479 1.555 .940 .060

Table 7. Summary of interoccurrence intervals for daily precipitation thresholds of 2.5 and 3.0 inches—Continued

Seq.

no.

Daily precipitation threshold of 2.5 inches and greater Daily precipitation threshold of 3.0 inches and greater

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue
Table 7 185

721 223.65 163 36,455 3059467 .658 .745 .255 364.55 100 36,455 1958814 1.293 .902 .098

722 322.80 5 1,614 2731 -1.252 .105 .105 322.80 5 1,614 2731 -1.252 .105 .105

723 102.36 22 2,252 24115 -.216 .415 .415 281.50 8 2,252 8589 -.228 .410 .410

724 277.30 33 9,151 160242 .610 .729 .271 435.76 21 9,151 104742 .715 .763 .237

725 339.33 27 9,162 129868 .450 .674 .326 509.00 18 9,162 93070 .946 .828 .172

726 388.33 3 1,165 1120 -1.077 .141 .141 -- -- -- -- -- -- --

727 173.16 146 25,281 1746115 -1.127 .130 .130 297.42 85 25,281 1043129 -.465 .321 .321

728 141.16 73 10,305 429267 2.091 .982 .018 229.00 45 10,305 253264 1.073 .858 .142

729 208.16 31 6,453 119516 1.880 .970 .030 322.65 20 6,453 75974 1.374 .915 .085

730 -- -- -- -- -- -- -- -- -- -- -- -- -- --

731 260.50 24 6,252 71974 -.345 .365 .365 521.00 12 6,252 38138 .100 .540 .460

732 487.07 14 6,819 61100 1.815 .965 .035 757.67 9 6,819 42702 2.035 .979 .021

733 -- -- -- -- -- -- -- -- -- -- -- -- -- --

734 2305.70 10 23,057 91896 -1.111 .133 .133 11528.50 2 23,057 14440 -.915 .180 .180

735 -- -- -- -- -- -- -- -- -- -- -- -- -- --

736 368.00 22 8,096 122399 3.042 .999 .001 539.73 15 8,096 74929 1.570 .942 .058

737 2647.00 1 2,647 2018 .909 .818 .182 2647.00 1 2,647 2018 .909 .818 .182

738 3583.25 4 14,333 42775 1.705 .956 .044 -- -- -- -- -- -- --

739 -- -- -- -- -- -- -- -- -- -- -- -- -- --

740 -- -- -- -- -- -- -- -- -- -- -- -- -- --

741 -- -- -- -- -- -- -- -- -- -- -- -- -- --

742 228.16 116 26,466 1490994 -.535 .296 .296 490.11 54 26,466 702465 -.216 .415 .415

743 191.93 174 33,395 2979786 .585 .721 .279 407.26 82 33,395 1407923 .444 .671 .329

744 333.32 19 6,333 49062 -1.393 .082 .082 575.73 11 6,333 30571 -.703 .241 .241

745 358.16 25 8,954 120010 .626 .734 .266 559.63 16 8,954 75049 .331 .630 .371

746 342.53 60 20,552 672589 1.219 .889 .111 622.79 33 20,552 385072 1.349 .911 .089

747 559.11 35 19,569 379542 1.110 .866 .134 978.45 20 19,569 247345 2.045 .980 .020

748 129.20 255 32,946 4049576 -.995 .160 .160 184.06 179 32,946 2808242 -1.104 .135 .135

749 208.82 65 13,573 373074 -2.154 .016 .016 331.05 41 13,573 251342 -1.072 .142 .142

750 137.62 135 18,579 1481557 3.650 1.000 0 213.55 87 18,579 983878 3.512 1.000 0

751 152.56 50 7,628 183065 -.490 .312 .312 246.07 31 7,628 102111 -1.315 .094 .094

752 -- -- -- -- -- -- -- -- -- -- -- -- -- --

753 508.25 4 2,033 4232 .141 .556 .444 2033.00 1 2,033 1004 -.021 .491 .491

754 214.58 12 2,575 14516 -.363 .358 .358 429.17 6 2,575 5520 -1.211 .113 .113

755 358.32 60 21,499 631296 -.284 .388 .388 551.26 39 21,499 437608 .474 .682 .318

756 -- -- -- -- -- -- -- -- -- -- -- -- -- --

757 649.33 9 5,844 30902 .910 .818 .182 1461.00 4 5,844 13935 .666 .747 .253

758 204.71 158 32,344 2660822 .900 .816 .184 363.42 89 32,344 1561756 1.390 .918 .082

759 427.56 36 15,392 317956 1.534 .937 .063 810.11 19 15,392 185183 2.012 .978 .022

760 374.47 57 21,345 635682 .588 .722 .278 576.89 37 21,345 416676 .582 .720 .281

761 322.17 42 13,531 278970 -.205 .419 .419 501.15 27 13,531 211433 1.417 .922 .078

762 1487.71 17 25,291 214916 -.002 .499 .499 2529.10 10 25,291 150373 1.036 .850 .150

763 236.80 5 1,184 3473 .671 .749 .251 394.67 3 1,184 2359 .985 .838 .162

764 270.93 121 32,783 1832118 -1.453 .073 .073 520.37 63 32,783 865933 -2.220 .013 .013

765 174.21 70 12,195 488083 2.080 .981 .019 290.36 42 12,195 301508 1.991 .977 .023

766 148.56 18 2,674 19355 -1.439 .075 .075 191.00 14 2,674 13976 -1.642 .050 .050

767 721.78 46 33,202 929109 2.545 .995 .005 1844.56 18 33,202 392417 2.302 .989 .011

768 418.83 81 33,925 1366514 -.085 .466 .466 721.81 47 33,925 821551 .362 .641 .359

Table 7. Summary of interoccurrence intervals for daily precipitation thresholds of 2.5 and 3.0 inches—Continued

Seq.

no.

Daily precipitation threshold of 2.5 inches and greater Daily precipitation threshold of 3.0 inches and greater

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue
186 Atlas of Interoccurrence Intervals for Selected Thresholds of Daily Precipitation in Texas 

769 529.50 4 2,118 6258 1.654 .951 .049 1059.00 2 2,118 2958 .972 .834 .166

770 1356.00 6 8,136 24110 -.052 .479 .479 2034.00 4 8,136 12458 -.812 .208 .208

771 1238.00 3 3,714 7276 .918 .821 .179 1857.00 2 3,714 3750 .024 .509 .491

772 91.50 2 183 247 .857 .804 .196 183.00 1 183 85 -.123 .451 .451

773 129.25 4 517 852 -.610 .271 .271 129.25 4 517 852 -.610 .271 .271

774 335.54 92 30,870 1524880 1.227 .890 .110 551.25 56 30,870 938028 1.105 .865 .135

775 -- -- -- -- -- -- -- -- -- -- -- -- -- --

776 241.90 29 7,015 111218 .871 .808 .192 350.75 20 7,015 78379 .909 .818 .182

777 253.78 27 6,852 72038 -1.991 .023 .023 428.25 16 6,852 52407 -.305 .380 .380

778 1218.63 8 9,749 31065 -.996 .160 .160 1949.80 5 9,749 17318 -1.121 .131 .131

779 640.28 25 16,007 239213 1.693 .955 .045 1333.92 12 16,007 100539 .281 .611 .389

780 215.99 160 34,558 2802517 .300 .618 .382 367.64 94 34,558 1691762 .698 .757 .243

781 752.48 46 34,614 778187 -.265 .396 .396 1282.00 27 34,614 433811 -.645 .260 .260

782 145.36 64 9,303 308031 .481 .685 .315 244.82 38 9,303 186278 .575 .717 .283

783 730.00 2 1,460 1797 .565 .714 .286 1460.00 1 1,460 788 .138 .555 .445

784 944.20 5 4,721 9749 -.674 .250 .250 -- -- -- -- -- -- --

785 1059.94 18 19,079 164141 -.324 .373 .373 2119.89 9 19,079 93339 .453 .675 .325

786 1628.42 12 19,541 136926 1.007 .843 .157 3256.83 6 19,541 70619 .868 .807 .193

787 178.09 34 6,055 98781 -.408 .342 .342 403.67 15 6,055 42181 -.477 .317 .317

788 161.20 10 1,612 7810 -.170 .433 .433 230.29 7 1,612 5262 -.309 .379 .379

789 189.64 44 8,344 199022 .967 .833 .167 309.04 27 8,344 121466 .705 .760 .241

790 138.69 16 2,219 15521 -.871 .192 .192 221.90 10 2,219 10203 -.440 .330 .330

791 168.36 28 4,714 79423 1.865 .969 .031 392.83 12 4,714 33580 1.124 .869 .131

792 225.00 2 450 568 .642 .740 .260 450.00 1 450 321 .739 .770 .230

793 206.25 93 19,181 869477 -.420 .337 .337 355.20 54 19,181 551576 .828 .796 .204

794 220.47 53 11,685 290823 -.767 .222 .222 292.13 40 11,685 218690 -.704 .241 .241

795 347.90 49 17,047 463478 1.330 .908 .092 532.72 32 17,047 302816 1.080 .860 .140

796 580.56 9 5,225 18621 -1.081 .140 .140 1045.00 5 5,225 8439 -1.371 .085 .085

797 364.86 78 28,459 1177849 .937 .825 .175 547.29 52 28,459 794564 .922 .822 .178

798 694.00 1 694 486 .694 .756 .244 -- -- -- -- -- -- --

799 653.93 14 9,155 62487 -.162 .436 .436 1017.22 9 9,155 46486 .667 .748 .252

800 1148.00 1 1,148 1038 1.400 .919 .081 -- -- -- -- -- -- --

801 1345.82 11 14,804 95775 1.013 .844 .156 4934.67 3 14,804 26062 .521 .699 .301

802 1512.00 1 1,512 98 -1.508 .066 .066 -- -- -- -- -- -- --

803 291.96 25 7,299 97553 .600 .726 .274 456.19 16 7,299 58613 .026 .510 .490

804 -- -- -- -- -- -- -- -- -- -- -- -- -- --

805 348.27 33 11,493 189212 -.022 .491 .491 522.41 22 11,493 129455 .195 .577 .423

806 178.76 96 17,161 802867 -.430 .334 .334 301.07 57 17,161 495754 .178 .571 .429

807 247.76 53 13,131 382246 1.242 .893 .107 410.34 32 13,131 222935 .599 .725 .275

808 295.28 61 18,012 555560 .153 .561 .439 514.63 35 18,012 318623 .111 .544 .456

809 737.68 25 18,442 221110 -.354 .362 .362 1229.47 15 18,442 134748 -.173 .431 .431

810 894.17 23 20,566 208784 -.974 .165 .165 1869.64 11 20,566 96961 -.820 .206 .206

811 189.13 39 7,376 140327 -.264 .396 .396 368.80 20 7,376 88572 1.556 .940 .060

812 393.18 17 6,684 73744 2.128 .983 .017 607.64 11 6,684 41595 .755 .775 .225

813 83.00 1 83 66 1.023 .847 .153 -- -- -- -- -- -- --

814 1626.93 15 24,404 186791 .138 .555 .445 4067.33 6 24,404 69937 -0.190 .425 .425

815 180.82 168 30,377 2826708 2.420 .992 .008 316.43 96 30,377 1593201 1.573 .942 .058

816 159.53 81 12,922 597782 2.217 .987 .013 243.81 53 12,922 391796 1.818 .965 .035

Table 7. Summary of interoccurrence intervals for daily precipitation thresholds of 2.5 and 3.0 inches—Continued

Seq.

no.

Daily precipitation threshold of 2.5 inches and greater Daily precipitation threshold of 3.0 inches and greater

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue
Table 7 187

817 270.44 23 6,220 72251 .084 .533 .467 478.46 13 6,220 41900 .227 .590 .410

818 254.27 78 19,833 778322 .096 .538 .462 508.54 39 19,833 366345 -.571 .284 .284

819 2061.57 14 28,862 202914 .028 .511 .489 2886.20 10 28,862 133961 -.393 .347 .347

820 222.75 4 891 2671 1.728 .958 .042 297.00 3 891 2348 2.271 .988 .012

821 1137.29 7 7,961 31755 .640 .739 .261 1990.25 4 7,961 24768 1.925 .973 .027

822 352.78 54 19,050 511960 -.059 .476 .476 595.31 32 19,050 326911 .711 .761 .239

823 451.94 72 32,540 1279043 1.350 .911 .089 723.11 45 32,540 793635 .976 .835 .165

824 530.50 4 2,122 4140 -.085 .466 .466 2122.00 1 2,122 1055 -.010 .496 .496

825 311.15 13 4,045 29859 .847 .801 .199 577.86 7 4,045 17981 1.238 .892 .108

826 187.97 141 26,503 1948909 .886 .812 .188 358.15 74 26,503 972314 -.126 .450 .450

827 153.49 68 10,437 402429 1.915 .972 .028 213.00 49 10,437 309125 2.533 .994 .006

828 198.67 130 25,827 1810486 1.550 .939 .061 379.81 68 25,827 916530 .625 .734 .266

829 120.02 45 5,401 125489 .379 .648 .352 192.89 28 5,401 85045 1.143 .873 .127

830 327.55 40 13,102 243938 -.757 .225 .225 623.91 21 13,102 126003 -.667 .252 .252

831 202.51 70 14,176 574007 2.274 .989 .011 329.67 43 14,176 355657 1.896 .971 .029

832 292.00 6 1,752 3993 -1.020 .154 .154 876.00 2 1,752 1221 -.742 .229 .229

833 1641.00 1 1,641 824 .007 .503 .497 1641.00 1 1,641 824 .007 .503 .497

834 456.22 9 4,106 23573 1.433 .924 .076 821.20 5 4,106 12485 .838 .799 .201

835 139.47 133 18,549 1279670 .748 .773 .227 268.83 69 18,549 721010 1.823 .966 .034

836 228.73 33 7,548 137692 1.051 .853 .147 377.40 20 7,548 80679 .534 .703 .297

837 145.63 82 11,942 514516 .797 .787 .213 265.38 45 11,942 268288 -.018 .493 .493

838 115.42 66 7,618 283463 1.795 .964 .036 173.14 44 7,618 197067 2.020 .978 .022

839 173.23 13 2,252 11184 -1.474 .070 .070 375.33 6 2,252 4502 -1.416 .078 .078

840 248.01 147 36,458 2858109 1.398 .919 .081 434.02 84 36,458 1656314 1.297 .903 .097

841 130.05 139 18,077 1389983 2.172 .985 .015 203.11 89 18,077 897057 1.882 .970 .030

842 146.34 128 18,731 1347306 2.428 .992 .008 217.80 86 18,731 921066 2.306 .989 .011

843 133.11 27 3,594 54436 1.098 .864 .136 211.41 17 3,594 31696 .268 .606 .394

844 307.98 57 17,555 445925 -1.422 .078 .078 548.59 32 17,555 239400 -1.447 .074 .074

845 138.52 27 3,740 56645 1.097 .864 .136 340.00 11 3,740 24902 1.210 .887 .113

846 98.14 66 6,477 224977 .740 .770 .230 147.21 44 6,477 152730 .825 .795 .205

847 289.26 62 17,934 520242 -.876 .191 .191 427.00 42 17,934 347190 -.877 .190 .190

848 256.81 112 28,763 1654961 .503 .693 .307 405.11 71 28,763 1071037 .714 .762 .238

849 169.63 40 6,785 134780 -.074 .470 .470 376.94 18 6,785 55013 -.728 .233 .233

850 1431.00 1 1,431 866 .364 .642 .358 -- -- -- -- -- -- --

851 -- -- -- -- -- -- -- -- -- -- -- -- -- --

852 114.25 4 457 959 .171 .568 .432 228.50 2 457 387 -.375 .354 .354

853 -- -- -- -- -- -- -- -- -- -- -- -- -- --

854 609.65 31 18,899 318893 .855 .804 .196 1049.94 18 18,899 200671 1.321 .907 .093

855 192.07 29 5,570 84811 .467 .680 .320 278.50 20 5,570 55095 -.084 .466 .466

856 850.41 22 18,709 188180 -.696 .243 .243 1870.90 10 18,709 93330 -.013 .495 .495

857 413.64 22 9,100 113494 1.087 .861 .139 827.27 11 9,100 41160 -1.020 .154 .154

858 587.78 18 10,580 117152 1.693 .955 .045 813.85 13 10,580 86762 1.634 .949 .051

859 720.54 13 9,367 61363 .049 .520 .480 1561.17 6 9,367 22398 -.861 .195 .195

860 -- -- -- -- -- -- -- -- -- -- -- -- -- --

861 498.10 29 14,445 179025 -1.355 .088 .088 802.50 18 14,445 121394 -0.487 .313 .313

862 331.83 23 7,632 69679 -1.712 .043 .043 693.82 11 7,632 39801 -.298 .383 .383

863 426.00 1 426 374 1.309 .905 .095 426.00 1 426 374 1.309 .905 .095

864 1389.92 13 18,069 106100 -.603 .273 .273 2007.67 9 18,069 80780 -.034 .486 .486

Table 7. Summary of interoccurrence intervals for daily precipitation thresholds of 2.5 and 3.0 inches—Continued

Seq.

no.

Daily precipitation threshold of 2.5 inches and greater Daily precipitation threshold of 3.0 inches and greater

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue
188 Atlas of Interoccurrence Intervals for Selected Thresholds of Daily Precipitation in Texas 

865 585.50 4 2,342 4363 -.237 .406 .406 1171.00 2 2,342 2112 -.241 .405 .405

866 680.25 4 2,721 4927 -.328 .372 .372 907.00 3 2,721 4710 .462 .678 .322

867 317.98 50 15,899 395631 -.057 .477 .477 529.97 30 15,899 239323 .033 .513 .487

868 282.42 77 21,746 897011 1.085 .861 .139 453.04 48 21,746 531550 .222 .588 .412

869 970.53 19 18,440 155601 -.844 .199 .199 1676.36 11 18,440 96916 -.255 .399 .399

870 225.00 7 1,575 6773 1.048 .853 .147 393.75 4 1,575 5071 2.113 .983 .017

871 -- -- -- -- -- -- -- -- -- -- -- -- -- --

872 -- -- -- -- -- -- -- -- -- -- -- -- -- --

873 92.40 254 23,470 2972341 -.077 .469 .469 136.45 172 23,470 2023357 .056 .522 .478

874 73.39 78 5,724 214344 -.609 .271 .271 110.08 52 5,724 145786 -.255 .399 .399

875 242.50 2 485 545 .303 .619 .381 242.50 2 485 545 .303 .619 .381

876 -- -- -- -- -- -- -- -- -- -- -- -- -- --

877 -- -- -- -- -- -- -- -- -- -- -- -- -- --

878 178.02 88 15,666 638615 -1.195 .116 .116 326.38 48 15,666 317581 -1.864 .031 .031

879 596.55 31 18,493 253063 -1.130 .129 .129 1087.82 17 18,493 122090 -1.595 .055 .055

880 -- -- -- -- -- -- -- -- -- -- -- -- -- --

881 531.29 35 18,595 310327 -.475 .317 .317 929.75 20 18,595 200733 .616 .731 .269

882 228.25 8 1,826 7702 .267 .605 .395 365.20 5 1,826 3846 -.610 .271 .271

883 473.96 23 10,901 137140 .781 .782 .218 726.73 15 10,901 103543 1.788 .963 .037

884 592.65 23 13,631 173040 .863 .806 .194 1239.18 11 13,631 84340 .718 .764 .236

885 479.00 62 29,698 911065 -.142 .444 .444 958.00 31 29,698 416972 -.908 .182 .182

886 128.71 166 21,366 1857597 1.060 .855 .145 194.24 110 21,366 1221233 .713 .762 .238

887 191.44 131 25,079 1740833 1.185 .882 .118 338.91 74 25,079 1045190 1.883 .970 .030

888 295.77 64 18,929 693264 2.002 .977 .023 728.04 26 18,929 273296 .977 .836 .164

889 1372.60 10 13,726 84473 1.264 .897 .103 2745.20 5 13,726 37964 .412 .660 .340

890 1090.42 12 13,085 96387 1.366 .914 .086 1635.63 8 13,085 64057 1.097 .864 .136

891 490.35 37 18,143 375887 1.263 .897 .103 788.83 23 18,143 208158 -.019 .492 .492

892 425.06 17 7,226 68727 .850 .802 .198 602.17 12 7,226 53356 1.384 .917 .083

893 928.93 29 26,939 405852 .364 .642 .358 1584.65 17 26,939 217951 -.344 .365 .365

894 563.10 10 5,631 22636 -1.074 .142 .142 1126.20 5 5,631 13153 -.254 .400 .400

895 4267.75 4 17,071 42176 .815 .792 .208 5690.33 3 17,071 30356 .556 .711 .289

896 182.42 196 35,755 3918575 2.869 .998 .002 343.80 104 35,755 2197567 3.214 .999 .001

897 -- -- -- -- -- -- -- -- -- -- -- -- -- --

898 121.10 10 1,211 7465 1.276 .899 .101 134.56 9 1,211 6300 .811 .791 .209

899 58.00 1 58 20 -.538 .296 .296 -- -- -- -- -- -- --

900 510.33 3 1,531 2951 .855 .804 .196 1531.00 1 1,531 987 .501 .692 .308

901 358.42 95 34,050 1559206 -.607 .272 .272 577.12 59 34,050 992387 -.160 .436 .436

902 224.80 5 1,124 2072 -1.017 .155 .155 224.80 5 1,124 2072 -1.017 .155 .155

903 1944.31 13 25,276 206204 1.593 .944 .056 5055.20 5 25,276 77947 .905 .817 .183

904 -- -- -- -- -- -- -- -- -- -- -- -- -- --

905 1511.46 11 16,626 103808 .777 .781 .219 2771.00 6 16,626 50755 .075 .530 .470

906 930.32 34 31,631 607720 1.315 .906 .094 1506.24 21 31,631 391822 1.427 .923 .077

907 -- -- -- -- -- -- -- -- -- -- -- -- -- --

908 1236.38 16 19,782 162355 .179 .571 .429 2472.75 8 19,782 87480 .517 .697 .303

909 762.91 11 8,392 51951 0.721 .765 .235 1049.00 8 8,392 35323 0.256 .601 .399

910 7085.00 1 7,085 4153 .299 .617 .383 -- -- -- -- -- -- --

911 -- -- -- -- -- -- -- -- -- -- -- -- -- --

912 302.00 1 302 284 1.526 .936 .064 -- -- -- -- -- -- --

Table 7. Summary of interoccurrence intervals for daily precipitation thresholds of 2.5 and 3.0 inches—Continued

Seq.

no.

Daily precipitation threshold of 2.5 inches and greater Daily precipitation threshold of 3.0 inches and greater

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue
Table 7 189

913 247.00 26 6,422 106701 2.456 .993 .007 356.78 18 6,422 74430 2.115 .983 .017

914 517.43 7 3,622 13236 .202 .580 .420 724.40 5 3,622 7918 -.486 .313 .313

915 168.25 200 33,649 3644703 2.037 .979 .021 232.06 145 33,649 2783351 2.939 .998 .002

916 182.20 105 19,131 1110048 1.867 .969 .031 281.34 68 19,131 757441 2.349 .991 .009

917 1541.80 5 7,709 8792 -2.106 .018 .018 2569.67 3 7,709 5508 -1.571 .058 .058

918 121.32 73 8,856 358356 1.608 .946 .054 205.95 43 8,856 226099 2.129 .983 .017

919 408.38 24 9,801 131994 1.038 .850 .150 700.07 14 9,801 79910 1.068 .857 .143

920 172.11 111 19,104 1127688 1.160 .877 .123 341.14 56 19,104 600455 1.588 .944 .056

921 397.09 11 4,368 25749 .413 .660 .340 728.00 6 4,368 14540 .465 .679 .321

922 909.76 25 22,744 283131 -.036 .486 .486 1624.57 14 22,744 167475 .337 .632 .368

923 955.06 35 33,427 562473 -.394 .347 .347 2228.47 15 33,427 279560 .772 .780 .220

924 639.00 1 639 399 .431 .667 .333 639.00 1 639 399 .431 .667 .333

925 4205.00 1 4,205 3372 1.046 .852 .148 4205.00 1 4,205 3372 1.046 .852 .148

926 185.33 3 556 1192 1.288 .901 .099 556.00 1 556 171 -.667 .253 .253

927 184.71 24 4,433 53943 .119 .547 .453 277.06 16 4,433 34666 -.156 .438 .438

928 952.88 8 7,623 37698 1.158 .876 .124 2541.00 3 7,623 11135 -.079 .469 .469

929 119.06 132 15,716 1009537 -.532 .297 .297 176.58 89 15,716 701700 .055 .522 .478

930 569.25 16 9,108 75679 .268 .606 .394 1301.14 7 9,108 32267 .056 .522 .478

931 372.54 13 4,843 46786 3.037 .999 .001 1210.75 4 4,843 13435 1.341 .910 .090

932 361.67 9 3,255 16349 .604 .727 .273 465.00 7 3,255 13407 .810 .791 .209

933 -- -- -- -- -- -- -- -- -- -- -- -- -- --

934 138.68 40 5,547 118182 .715 .763 .237 205.44 27 5,547 76593 .205 .581 .419

935 108.21 182 19,694 2007396 2.806 .998 .003 171.25 115 19,694 1209426 1.263 .897 .103

936 115.98 82 9,510 364108 -1.038 .150 .150 161.19 59 9,510 271664 -.421 .337 .337

937 91.96 97 8,920 422174 -.412 .340 .340 148.67 60 8,920 261623 -.300 .382 .382

938 269.27 94 25,311 1326043 1.926 .973 .027 414.93 61 25,311 814784 .750 .773 .227

939 133.36 162 21,605 1934249 2.321 .990 .010 198.21 109 21,605 1282467 1.613 .947 .053

940 299.96 53 15,898 379843 -1.241 .107 .107 387.76 41 15,898 288452 -1.275 .101 .101

941 169.61 97 16,452 726174 -1.534 .063 .063 228.50 72 16,452 566102 -.649 .258 .258

942 468.96 28 13,131 182218 -.081 .468 .468 1193.73 11 13,131 60252 -.952 .171 .171

943 640.14 51 32,647 877312 .666 .747 .253 960.21 34 32,647 582120 .494 .689 .311

944 212.59 27 5,740 63041 -1.678 .047 .047 318.89 18 5,740 42307 -1.330 .092 .092

945 277.43 77 21,362 876279 .995 .840 .160 403.06 53 21,362 574931 .197 .578 .422

946 228.37 43 9,820 264668 2.880 .998 .002 363.70 27 9,820 166682 2.316 .990 .010

947 275.68 50 13,784 372931 1.007 .843 .157 353.44 39 13,784 293910 1.011 .844 .156

948 1216.00 1 1,216 472 -.387 .349 .349 -- -- -- -- -- -- --

949 6627.25 4 26,509 52092 -.061 .476 .476 8836.33 3 26,509 33947 -.439 .330 .330

950 -- -- -- -- -- -- -- -- -- -- -- -- -- --

951 206.75 60 12,405 371300 -.031 .488 .488 375.91 33 12,405 225523 1.013 .844 .156

952 273.83 18 4,929 48675 .715 .763 .238 492.90 10 4,929 32298 1.701 .956 .045

953 280.52 50 14,026 391288 1.419 .922 .078 500.93 28 14,026 202292 .277 .609 .391

954 203.59 34 6,922 106987 -.917 .180 .180 256.37 27 6,922 85114 -.803 .211 .211

955 472.21 70 33,055 1131683 -.316 .376 .376 944.43 35 33,055 554009 -.433 .332 .332

956 496.23 70 34,736 1300085 1.005 .843 .157 914.11 38 34,736 663728 .061 .524 .476

957 194.68 22 4,283 46427 -0.118 .453 .453 428.30 10 4,283 17308 -1.050 .147 .147

958 1140.27 11 12,543 73088 .342 .634 .366 2090.50 6 12,543 42492 .548 .708 .292

959 191.99 72 13,823 504691 .209 .583 .417 337.15 41 13,823 318145 1.361 .913 .087

960 390.50 2 781 1231 1.411 .921 .079 781.00 1 781 767 1.670 .953 .047

Table 7. Summary of interoccurrence intervals for daily precipitation thresholds of 2.5 and 3.0 inches—Continued

Seq.

no.

Daily precipitation threshold of 2.5 inches and greater Daily precipitation threshold of 3.0 inches and greater

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue
190 Atlas of Interoccurrence Intervals for Selected Thresholds of Daily Precipitation in Texas 

961 340.51 59 20,090 701628 2.446 .993 .007 627.81 32 20,090 380876 1.812 .965 .035

962 -- -- -- -- -- -- -- -- -- -- -- -- -- --

963 285.25 4 1,141 1776 -.768 .221 .221 380.33 3 1,141 1411 -.527 .299 .299

964 335.83 6 2,015 6906 .604 .727 .273 671.67 3 2,015 4841 1.805 .964 .036

965 351.52 29 10,194 111314 -2.303 .011 .011 463.36 22 10,194 78699 -2.422 .008 .008

966 987.67 9 8,889 42380 .309 .621 .379 1777.80 5 8,889 25183 .516 .697 .303

967 1010.80 5 5,054 12442 -.059 .476 .476 1684.67 3 5,054 6372 -.478 .316 .316

968 197.88 8 1,583 5012 -1.021 .154 .154 395.75 4 1,583 1934 -1.348 .089 .089

969 202.83 6 1,217 4386 .854 .803 .197 243.40 5 1,217 3637 .757 .775 .225

970 297.66 110 32,743 1860896 .606 .728 .272 461.17 71 32,743 1145670 -.210 .417 .417

971 191.33 9 1,722 8159 .275 .608 .392 215.25 8 1,722 7761 .621 .733 .267

972 411.69 45 18,526 459772 1.197 .884 .116 686.15 27 18,526 291829 1.502 .933 .067

973 1149.47 17 19,541 217639 2.216 .987 .013 1776.46 11 19,541 142063 1.849 .968 .032

974 253.66 44 11,161 236539 -.421 .337 .337 338.21 33 11,161 181505 -.143 .443 .443

975 193.81 64 12,404 349579 -1.653 .049 .049 354.40 35 12,404 199092 -.849 .198 .198

976 444.00 2 888 1649 2.099 .982 .018 888.00 1 888 849 1.580 .943 .057

977 -- -- -- -- -- -- -- -- -- -- -- -- -- --

978 157.11 85 13,354 626544 1.660 .952 .048 238.46 56 13,354 431514 1.997 .977 .023

979 158.75 36 5,715 116666 1.394 .918 .082 197.07 29 5,715 94507 1.310 .905 .095

980 123.21 29 3,573 55034 .581 .719 .281 170.14 21 3,573 33589 -.831 .203 .203

981 -- -- -- -- -- -- -- -- -- -- -- -- -- --

982 193.00 2 386 352 -.216 .415 .415 193.00 2 386 352 -.216 .415 .415

983 201.06 52 10,455 253090 -.861 .195 .195 387.22 27 10,455 132478 -.553 .290 .290

984 392.67 9 3,534 18044 .700 .758 .242 589.00 6 3,534 11856 .502 .692 .308

985 242.40 5 1,212 3885 1.093 .863 .137 606.00 2 1,212 853 -.726 .234 .234

986 288.75 12 3,465 20303 -.141 .444 .444 866.25 4 3,465 7567 .318 .625 .375

987 244.27 92 22,473 915543 -1.900 .029 .029 368.41 61 22,473 613290 -1.424 .077 .077

988 335.14 7 2,346 8173 -.021 .492 .492 391.00 6 2,346 6729 -.186 .426 .426

989 156.88 103 16,159 905214 1.543 .939 .061 273.88 59 16,159 484756 .225 .589 .411

990 216.73 86 18,639 833595 .644 .740 .260 423.61 44 18,639 449108 1.094 .863 .137

991 357.19 52 18,574 552897 1.810 .965 .035 663.36 28 18,574 291409 1.106 .866 .134

992 172.32 116 19,989 1257285 1.576 .942 .058 263.01 76 19,989 805619 .915 .820 .180

993 342.25 4 1,369 3138 .506 .694 .306 684.50 2 1,369 1538 .302 .619 .381

994 343.17 18 6,177 61427 .771 .780 .220 514.75 12 6,177 45343 1.341 .910 .090

995 270.00 61 16,470 482977 -.521 .301 .301 588.21 28 16,470 233058 .099 .539 .461

996 389.87 74 28,850 1238825 2.392 .992 .008 601.04 48 28,850 792178 1.729 .958 .042

997 235.51 117 27,555 1851470 2.784 .997 .003 372.37 74 27,555 1149022 1.892 .971 .029

998 260.05 82 21,324 949908 1.357 .913 .087 380.79 56 21,324 646790 1.079 .860 .140

999 192.05 19 3,649 27596 -1.540 .062 .062 280.69 13 3,649 21818 -.500 .308 .308

1000 180.16 50 9,008 230634 .296 .616 .384 360.32 25 9,008 100232 -.951 .171 .171

1001 219.04 90 19,714 992020 1.943 .974 .026 358.44 55 19,714 644241 2.419 .992 .008

1002 -- -- -- -- -- -- -- -- -- -- -- -- -- --

1003 473.40 43 20,356 475437 .981 .837 .163 848.17 24 20,356 238934 -.185 .426 .426

1004 208.00 98 20,384 958238 -.697 .243 .243 304.24 67 20,384 721270 .797 .787 .213

1005 547.33 39 21,346 381146 -0.912 .181 .181 928.09 23 21,346 233028 -0.421 .337 .337

1006 157.22 18 2,830 20481 -1.439 .075 .075 283.00 10 2,830 14930 .302 .619 .381

1007 188.02 45 8,461 170739 -1.198 .115 .115 282.03 30 8,461 114386 -.937 .175 .175

1008 210.52 66 13,894 414298 -1.357 .087 .087 338.88 41 13,894 277298 -.293 .385 .385

Table 7. Summary of interoccurrence intervals for daily precipitation thresholds of 2.5 and 3.0 inches—Continued

Seq.

no.

Daily precipitation threshold of 2.5 inches and greater Daily precipitation threshold of 3.0 inches and greater

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue
Table 7 191

1009 176.44 71 12,527 421705 -.755 .225 .225 291.33 43 12,527 243795 -1.077 .141 .141

1010 156.55 100 15,655 723135 -1.319 .094 .094 233.66 67 15,655 493278 -.843 .200 .200

1011 340.07 60 20,404 636056 .525 .700 .300 618.30 33 20,404 323636 -.385 .350 .350

1012 427.57 7 2,993 13692 1.407 .920 .080 997.67 3 2,993 4928 .293 .615 .385

1013 331.06 33 10,925 160991 -1.064 .144 .144 496.59 22 10,925 98277 -1.480 .069 .069

1014 195.17 12 2,342 16307 .963 .832 .168 292.75 8 2,342 10711 .702 .759 .241

1015 427.00 1 427 208 -.045 .482 .482 427.00 1 427 208 -.045 .482 .482

1016 183.83 109 20,037 1114116 .366 .643 .357 323.18 62 20,037 644480 .512 .696 .304

1017 373.40 5 1,867 5265 .496 .690 .310 373.40 5 1,867 5265 .496 .690 .310

1018 161.40 15 2,421 16296 -.688 .246 .246 201.75 12 2,421 13471 -.436 .332 .332

1019 537.47 15 8,062 58019 -.271 .393 .393 806.20 10 8,062 37309 -.408 .342 .342

1020 981.33 6 5,888 16295 -.329 .371 .371 1472.00 4 5,888 12829 .310 .622 .378

1021 551.21 44 24,253 587622 1.164 .878 .122 1010.54 24 24,253 309259 .531 .702 .298

1022 186.32 53 9,875 270568 .428 .666 .334 365.74 27 9,875 135784 .167 .566 .434

1023 232.41 29 6,740 69882 -2.658 .004 .004 337.00 20 6,740 46631 -2.387 .008 .008

1024 205.74 57 11,727 349669 .605 .727 .273 344.91 34 11,727 186611 -.646 .259 .259

1025 470.67 6 2,824 11607 1.570 .942 .058 706.00 4 2,824 7265 .992 .839 .161

1026 254.85 75 19,114 781552 1.356 .912 .088 406.68 47 19,114 500729 1.363 .914 .087

1027 307.18 22 6,758 66917 -.811 .209 .209 563.17 12 6,758 32366 -1.211 .113 .113

1028 463.93 59 27,372 785252 -.366 .357 .357 977.57 28 27,372 397682 .346 .635 .365

1029 242.94 64 15,548 553133 1.548 .939 .061 420.22 37 15,548 344440 2.081 .981 .019

1030 214.84 57 12,246 378241 1.095 .863 .137 395.03 31 12,246 205875 .816 .793 .207

1031 2538.00 1 2,538 1142 -.173 .431 .431 -- -- -- -- -- -- --

1032 254.85 143 36,443 2680884 .598 .725 .275 418.89 87 36,443 1652113 .681 .752 .248

1033 168.77 127 21,434 1518922 2.264 .988 .012 285.79 75 21,434 902804 1.848 .968 .032

1034 541.00 4 2,164 3908 -.336 .368 .368 1082.00 2 2,164 2548 .435 .668 .332

1035 341.47 99 33,805 1561477 -1.152 .125 .125 545.24 62 33,805 925140 -1.598 .055 .055

1036 76.57 7 536 2083 .506 .693 .307 134.00 4 536 1186 .368 .644 .356

1037 106.50 4 426 440 -1.675 .047 .047 106.50 4 426 440 -1.675 .047 .047

1038 231.40 15 3,471 24601 -.369 .356 .356 433.88 8 3,471 14728 .298 .617 .383

1039 -- -- -- -- -- -- -- -- -- -- -- -- -- --

1040 1717.75 4 6,871 19283 1.397 .919 .081 3435.50 2 6,871 8942 .738 .770 .230

1041 -- -- -- -- -- -- -- -- -- -- -- -- -- --

1042 108.90 114 12,414 744369 .961 .832 .168 172.42 72 12,414 478346 1.034 .849 .151

1043 -- -- -- -- -- -- -- -- -- -- -- -- -- --

1044 744.36 11 8,188 39842 -.662 .254 .254 1637.60 5 8,188 15234 -.991 .161 .161

1045 952.33 21 19,999 202155 -.296 .384 .384 1999.90 10 19,999 97993 -.110 .456 .456

1046 170.60 10 1,706 10357 1.173 .880 .120 213.25 8 1,706 8696 1.344 .910 .090

1047 252.64 80 20,211 857101 .933 .824 .176 404.22 50 20,211 508054 .067 .527 .473

1048 353.24 34 12,010 209462 .262 .603 .397 706.47 17 12,010 109060 .488 .687 .313

1049 306.06 16 4,897 37920 -.222 .412 .412 349.79 14 4,897 33447 -.157 .437 .437

1050 146.87 82 12,043 533487 1.262 .896 .104 280.07 43 12,043 275323 .719 .764 .236

1051 255.21 70 17,865 629107 .089 .535 .465 372.19 48 17,865 414089 -.411 .341 .341

1052 241.33 3 724 483 -1.666 .048 .048 -- -- -- -- -- -- --

1053 130.50 8 1,044 4268 0.108 .543 .457 348.00 3 1,044 2145 1.109 .866 .134

1054 -- -- -- -- -- -- -- -- -- -- -- -- -- --

1055 152.00 22 3,344 41461 1.033 .849 .151 222.93 15 3,344 28758 .984 .837 .163

1056 300.29 7 2,102 6830 -.328 .371 .371 420.40 5 2,102 3562 -1.248 .106 .106

Table 7. Summary of interoccurrence intervals for daily precipitation thresholds of 2.5 and 3.0 inches—Continued

Seq.

no.

Daily precipitation threshold of 2.5 inches and greater Daily precipitation threshold of 3.0 inches and greater

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue
192 Atlas of Interoccurrence Intervals for Selected Thresholds of Daily Precipitation in Texas 

1057 508.00 1 508 29 -1.534 .063 .063 -- -- -- -- -- -- --

1058 225.94 156 35,247 2807754 .460 .677 .323 367.16 96 35,247 1724461 .327 .628 .372

1059 178.75 4 715 664 -1.856 .032 .032 238.33 3 715 574 -1.394 .082 .082

1060 384.65 63 24,233 791852 .514 .696 .304 757.28 32 24,233 335016 -1.332 .091 .091

1061 -- -- -- -- -- -- -- -- -- -- -- -- -- --

1062 2080.00 1 2,080 1088 .080 .532 .468 -- -- -- -- -- -- --

1063 1084.96 22 23,869 334745 2.234 .987 .013 1491.81 16 23,869 243956 1.923 .973 .027

1064 -- -- -- -- -- -- -- -- -- -- -- -- -- --

1065 242.80 25 6,070 76278 .046 .518 .482 466.92 13 6,070 41914 .389 .651 .349

1066 258.44 43 11,113 262200 1.106 .866 .134 444.52 25 11,113 164366 1.587 .944 .056

1067 183.40 5 917 2370 .131 .552 .448 305.67 3 917 1418 .093 .537 .463

1068 358.00 2 716 365 -1.201 .115 .115 716.00 1 716 102 -1.239 .108 .108

1069 301.00 18 5,418 57351 1.294 .902 .098 602.00 9 5,418 21018 -.717 .237 .237

1070 242.93 145 35,225 2573640 .162 .564 .436 409.59 86 35,225 1539234 .260 .603 .397

1071 200.32 98 19,631 994956 .589 .722 .278 311.60 63 19,631 655151 .818 .793 .207

1072 238.29 7 1,668 3938 -1.491 .068 .068 834.00 2 1,668 629 -1.526 .064 .064

1073 -- -- -- -- -- -- -- -- -- -- -- -- -- --

1074 159.29 189 30,105 2784968 -.502 .308 .308 244.76 123 30,105 1912424 .633 .736 .264

1075 517.80 5 2,589 7112 .383 .649 .351 863.00 3 2,589 4372 .377 .647 .353

1076 273.44 66 18,047 632922 .883 .811 .189 410.16 44 18,047 414627 .509 .695 .305

1077 245.57 14 3,438 24114 .013 .505 .495 343.80 10 3,438 16247 -.301 .382 .382

1078 809.21 34 27,513 491466 .513 .696 .304 2501.18 11 27,513 159792 .322 .626 .374

1079 376.99 83 31,290 1325097 .323 .627 .373 782.25 40 31,290 695338 1.217 .888 .112

1080 161.33 3 484 1144 1.727 .958 .042 161.33 3 484 1144 1.727 .958 .042

1081 530.80 40 21,232 393100 -.814 .208 .208 1179.56 18 21,232 193660 .099 .539 .461

1082 684.75 20 13,695 167113 1.706 .956 .044 1369.50 10 13,695 95724 2.180 .985 .015

1083 964.38 16 15,430 132777 .524 .700 .300 1928.75 8 15,430 79221 1.389 .918 .082

1084 135.22 9 1,217 5255 -.210 .417 .417 152.13 8 1,217 4106 -.767 .222 .222

1085 220.21 165 36,335 3007268 .072 .529 .471 399.29 91 36,335 1736087 .828 .796 .204

1086 504.90 10 5,049 24453 -.172 .432 .432 1262.25 4 5,049 8646 -.498 .309 .309

1087 3512.50 4 14,050 21441 -.821 .206 .206 14050.00 1 14,050 6418 -.150 .440 .440

1088 112.60 20 2,252 24103 .545 .707 .293 187.67 12 2,252 13760 .110 .544 .456

1089 593.00 2 1,186 903 -.585 .279 .279 1186.00 1 1,186 127 -1.361 .087 .087

1090 424.17 24 10,180 133418 .782 .783 .217 598.82 17 10,180 104565 1.489 .932 .068

1091 895.46 22 19,700 193002 -.888 .187 .187 1970.00 10 19,700 76634 -1.216 .112 .112

1092 -- -- -- -- -- -- -- -- -- -- -- -- -- --

1093 158.57 30 4,757 53996 -2.308 .011 .011 237.85 20 4,757 37511 -1.638 .051 .051

1094 168.67 153 25,807 2221893 2.688 .996 .004 260.68 99 25,807 1390734 1.528 .937 .063

1095 152.15 13 1,978 13865 .490 .688 .312 247.25 8 1,978 8338 .264 .604 .396

1096 658.76 29 19,104 288596 .390 .652 .348 1469.54 13 19,104 142830 .938 .826 .174

1097 250.37 76 19,028 812215 1.862 .969 .031 396.42 48 19,028 489397 .860 .805 .195

1098 289.69 51 14,774 306031 -2.322 .010 .010 568.23 26 14,774 171346 -.953 .170 .170

1099 -- -- -- -- -- -- -- -- -- -- -- -- -- --

1100 235.00 12 2,820 20504 1.271 .898 .102 470.00 6 2,820 11325 1.437 .925 .075

1101 208.56 140 29,198 2013381 -0.306 .380 .380 351.78 83 29,198 1213065 0.018 .507 .493

1102 644.10 49 31,561 818145 .704 .759 .241 1502.91 21 31,561 364939 .804 .789 .211

1103 3488.67 3 10,466 17292 .304 .620 .380 -- -- -- -- -- -- --

1104 217.00 36 7,812 150738 .748 .773 .227 289.33 27 7,812 114332 .757 .775 .225

Table 7. Summary of interoccurrence intervals for daily precipitation thresholds of 2.5 and 3.0 inches—Continued

Seq.

no.

Daily precipitation threshold of 2.5 inches and greater Daily precipitation threshold of 3.0 inches and greater

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue
Table 7 193

1105 275.90 48 13,243 293559 -.916 .180 .180 472.96 28 13,243 153480 -1.578 .057 .057

1106 459.00 49 22,491 518642 -.713 .238 .238 775.55 29 22,491 334601 .243 .596 .404

1107 536.67 3 1,610 1656 -.943 .173 .173 805.00 2 1,610 1311 -.455 .325 .325

1108 -- -- -- -- -- -- -- -- -- -- -- -- -- --

1109 582.17 6 3,493 10286 -.078 .469 .469 1164.33 3 3,493 4270 -.555 .289 .289

1110 319.09 11 3,510 14867 -1.321 .093 .093 501.43 7 3,510 9955 -.869 .192 .192

1111 750.67 3 2,252 2172 -1.071 .142 .142 2252.00 1 2,252 264 -1.326 .092 .092

1112 141.37 85 12,016 564634 1.687 .954 .046 235.61 51 12,016 331172 1.000 .841 .159

1113 867.59 34 29,498 510778 .188 .574 .426 1404.67 21 29,498 333633 .613 .730 .270

1114 281.95 43 12,124 264763 .179 .571 .429 484.96 25 12,124 160900 .534 .703 .297

1115 1162.60 5 5,813 13637 -.239 .406 .406 2906.50 2 5,813 5390 -.178 .429 .429

1116 290.60 5 1,453 3404 -.244 .404 .404 363.25 4 1,453 2639 -.318 .375 .375

1117 209.69 75 15,727 626017 .922 .822 .178 327.65 48 15,727 390827 .425 .665 .335

1118 266.67 3 800 845 -.888 .187 .187 266.67 3 800 845 -.888 .187 .187

1119 344.82 22 7,586 84775 .129 .552 .448 689.64 11 7,586 44811 .425 .665 .335

1120 698.91 35 24,462 434611 .156 .562 .438 1630.80 15 24,462 202501 .696 .757 .243

1121 494.58 60 29,675 834804 -.836 .202 .202 847.86 35 29,675 541244 .433 .667 .333

1122 340.33 3 1,021 1194 -.661 .254 .254 1021.00 1 1,021 241 -.914 .180 .180

1123 393.17 58 22,804 654926 -.128 .449 .449 735.61 31 22,804 339870 -.371 .355 .355

1124 457.00 3 1,371 2994 1.368 .914 .086 -- -- -- -- -- -- --

1125 313.33 9 2,820 10877 -.742 .229 .229 564.00 5 2,820 7916 .476 .683 .317

1126 429.22 9 3,863 16506 -.262 .397 .397 551.86 7 3,863 10129 -1.150 .125 .125

1127 667.40 40 26,696 412280 -2.496 .006 .006 1160.70 23 26,696 218401 -2.397 .008 .008

1128 567.12 17 9,641 74203 -.675 .250 .250 964.10 10 9,641 46106 -.239 .406 .406

1129 599.67 6 3,598 12931 .840 .799 .201 899.50 4 3,598 10187 1.440 .925 .075

1130 -- -- -- -- -- -- -- -- -- -- -- -- -- --

1131 247.38 56 13,853 430543 1.426 .923 .077 461.77 30 13,853 231654 1.089 .862 .138

1132 -- -- -- -- -- -- -- -- -- -- -- -- -- --

1133 234.84 43 10,098 191113 -1.360 .087 .087 374.00 27 10,098 121751 -.962 .168 .168

1134 -- -- -- -- -- -- -- -- -- -- -- -- -- --

1135 112.71 7 789 2642 -.198 .421 .421 197.25 4 789 1536 -.092 .463 .463

1136 1393.75 20 27,875 294456 .436 .669 .331 3484.38 8 27,875 136342 1.092 .862 .138

1137 341.88 56 19,145 591056 1.330 .908 .092 736.35 26 19,145 247767 -.040 .484 .484

1138 -- -- -- -- -- -- -- -- -- -- -- -- -- --

1139 -- -- -- -- -- -- -- -- -- -- -- -- -- --

1140 397.75 28 11,137 142630 -.781 .217 .217 655.12 17 11,137 64925 -2.244 .012 .012

1141 150.11 133 19,965 1468634 2.121 .983 .017 249.56 80 19,965 901683 2.000 .977 .023

1142 162.76 201 32,715 3537710 1.866 .969 .031 268.16 122 32,715 2132713 1.314 .906 .094

1143 1502.50 6 9,015 20147 -1.082 .140 .140 2253.75 4 9,015 10291 -1.487 .069 .069

1144 240.10 10 2,401 13040 .472 .682 .318 400.17 6 2,401 8048 .498 .691 .309

1145 714.50 2 1,429 1602 .297 .617 .383 1429.00 1 1,429 962 .600 .726 .274

1146 665.58 40 26,623 502463 -.617 .269 .269 1023.96 26 26,623 326117 -.510 .305 .305

1147 365.18 17 6,208 52912 .020 .508 .492 620.80 10 6,208 33995 .521 .699 .301

1148 764.71 17 13,000 112287 .116 .546 .454 2166.67 6 13,000 41468 .269 .606 .394

1149 281.02 43 12,084 285524 1.124 .870 .131 464.77 26 12,084 171988 0.838 .799 .201

1150 960.21 14 13,443 104158 .693 .756 .244 1680.38 8 13,443 65307 1.051 .853 .147

1151 380.67 3 1,142 1697 -.028 .489 .489 571.00 2 1,142 1287 .311 .622 .378

1152 256.95 103 26,466 1416137 .685 .753 .247 413.53 64 26,466 898097 .837 .799 .201

Table 7. Summary of interoccurrence intervals for daily precipitation thresholds of 2.5 and 3.0 inches—Continued

Seq.

no.

Daily precipitation threshold of 2.5 inches and greater Daily precipitation threshold of 3.0 inches and greater

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue
194 Atlas of Interoccurrence Intervals for Selected Thresholds of Daily Precipitation in Texas 

1153 81.17 6 487 1493 .093 .537 .463 162.33 3 487 867 .561 .712 .288

1154 372.60 35 13,041 229232 .046 .518 .482 652.05 20 13,041 101540 -1.715 .043 .043

1155 171.13 8 1,369 4232 -1.113 .133 .133 273.80 5 1,369 1806 -1.829 .034 .034

1156 295.75 44 13,013 271996 -.574 .283 .283 448.72 29 13,013 157221 -1.556 .060 .060

1157 501.31 36 18,047 350315 .815 .792 .208 859.38 21 18,047 211563 .924 .822 .178

1158 209.53 17 3,562 36194 1.396 .919 .081 296.83 12 3,562 27437 1.703 .956 .044

1159 230.31 160 36,849 2895670 -.388 .349 .349 414.03 89 36,849 1571749 -.678 .249 .249

1160 467.00 3 1,401 918 -1.690 .046 .046 1401.00 1 1,401 28 -1.663 .048 .048

1161 440.00 13 5,720 37280 .017 .507 .493 715.00 8 5,720 16713 -1.321 .093 .093

1162 -- -- -- -- -- -- -- -- -- -- -- -- -- --

1163 -- -- -- -- -- -- -- -- -- -- -- -- -- --

1164 189.70 101 19,160 1027654 1.081 .860 .140 294.77 65 19,160 697767 1.683 .954 .046

1165 662.27 15 9,934 78612 .370 .644 .356 1241.75 8 9,934 37956 -.220 .413 .413

1166 176.31 68 11,989 430619 .806 .790 .210 278.81 43 11,989 281174 1.032 .849 .151

1167 198.56 34 6,751 101691 -1.151 .125 .125 375.06 18 6,751 55580 -.626 .266 .266

1168 1249.00 2 2,498 2278 -.216 .415 .415 2498.00 1 2,498 2037 1.093 .863 .137

1169 -- -- -- -- -- -- -- -- -- -- -- -- -- --

1170 163.73 101 16,537 874084 .812 .792 .208 246.82 67 16,537 534649 -.495 .310 .310

1171 272.16 45 12,247 299264 1.000 .841 .159 532.48 23 12,247 160007 1.130 .871 .129

1172 208.23 93 19,365 952875 .972 .834 .166 339.74 57 19,365 565318 .318 .625 .375

1173 290.04 82 23,783 955372 -.317 .375 .375 495.48 48 23,783 521110 -1.045 .148 .148

1174 282.22 18 5,080 52803 1.138 .872 .128 508.00 10 5,080 29841 .958 .831 .169

1175 467.67 58 27,125 748834 -.634 .263 .263 821.97 33 27,125 457414 .219 .587 .413

1176 -- -- -- -- -- -- -- -- -- -- -- -- -- --

1177 203.00 7 1,421 4861 -.104 .459 .459 284.20 5 1,421 3703 .164 .565 .435

1178 297.47 60 17,848 579849 1.113 .867 .133 482.38 37 17,848 363249 1.055 .854 .146

1179 398.48 44 17,533 362864 -.681 .248 .248 730.54 24 17,533 216652 .252 .600 .400

1180 558.33 3 1,675 2682 .202 .580 .420 1675.00 1 1,675 1559 1.492 .932 .068

1181 602.50 2 1,205 886 -.649 .258 .258 1205.00 1 1,205 826 .643 .740 .260

1182 134.46 72 9,681 343883 -.195 .423 .423 268.92 36 9,681 192904 1.112 .867 .133

1183 164.76 119 19,606 1271715 1.703 .956 .044 272.31 72 19,606 743658 .788 .785 .215

1184 8033.00 1 8,033 3174 -.363 .358 .358 -- -- -- -- -- -- --

1185 427.80 20 8,556 87421 .169 .567 .433 658.15 13 8,556 48501 -.799 .212 .212

1186 172.20 35 6,027 108885 .332 .630 .370 287.00 21 6,027 72765 1.189 .883 .117

1187 111.42 103 11,476 603223 .363 .642 .358 225.02 51 11,476 312236 .828 .796 .204

1188 2501.50 4 10,006 15291 -.817 .207 .207 3335.33 3 10,006 11083 -.785 .216 .216

1189 445.54 43 19,158 420638 .241 .595 .405 736.85 26 19,158 246927 -.075 .470 .470

1190 186.98 102 19,072 1113073 2.525 .994 .006 312.66 61 19,072 648658 1.557 .940 .060

1191 724.00 1 724 110 -1.206 .114 .114 724.00 1 724 110 -1.206 .114 .114

1192 498.77 13 6,484 40448 -.252 .401 .401 1296.80 5 6,484 14233 -.472 .318 .318

1193 224.62 34 7,637 131195 .106 .542 .458 363.67 21 7,637 80521 .033 .513 .487

1194 225.19 37 8,332 177257 1.580 .943 .057 362.26 23 8,332 102973 .620 .732 .268

1195 202.18 11 2,224 11209 -.480 .316 .316 317.71 7 2,224 8584 .471 .681 .319

1196 256.96 25 6,424 85637 .576 .718 .282 428.27 15 6,424 53876 .793 .786 .214

1197 347.63 57 19,815 570997 0.145 .558 .442 619.22 32 19,815 335112 0.559 .712 .288

1198 477.68 19 9,076 94090 .689 .754 .246 1008.44 9 9,076 47507 .848 .802 .198

1199 -- -- -- -- -- -- -- -- -- -- -- -- -- --

1200 399.75 36 14,391 255872 -.127 .449 .449 625.70 23 14,391 163209 -.115 .454 .454

Table 7. Summary of interoccurrence intervals for daily precipitation thresholds of 2.5 and 3.0 inches—Continued

Seq.

no.

Daily precipitation threshold of 2.5 inches and greater Daily precipitation threshold of 3.0 inches and greater

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue
Table 7 195

1201 958.50 2 1,917 2795 1.122 .869 .131 1917.00 1 1,917 1384 .769 .779 .221

1202 1293.33 15 19,400 189104 2.010 .978 .022 1616.67 12 19,400 153576 1.916 .972 .028

1203 461.59 34 15,694 237544 -1.107 .134 .134 980.88 16 15,694 115801 -.538 .295 .295

1204 673.09 23 15,481 217986 1.864 .969 .031 1290.08 12 15,481 119543 1.722 .957 .043

1205 135.10 48 6,485 158891 .251 .599 .401 240.19 27 6,485 89833 .235 .593 .407

1206 203.69 52 10,592 244908 -1.383 .083 .083 392.30 27 10,592 126919 -1.012 .156 .156

1207 210.48 29 6,104 99083 1.114 .867 .133 610.40 10 6,104 31759 .222 .588 .412

1208 928.86 21 19,506 206430 .063 .525 .475 1393.29 14 19,506 139794 .154 .561 .439

1209 -- -- -- -- -- -- -- -- -- -- -- -- -- --

1210 137.37 27 3,709 50158 .016 .506 .494 309.08 12 3,709 23360 .298 .617 .383

1211 275.11 102 28,061 1359494 -.875 .191 .191 425.17 66 28,061 961854 .545 .707 .293

1212 301.06 32 9,634 173148 1.208 .886 .114 401.42 24 9,634 123324 .566 .714 .286

1213 547.40 10 5,474 26954 -.083 .467 .467 782.00 7 5,474 18011 -.275 .392 .392

1214 241.33 3 724 1386 .829 .796 .204 362.00 2 724 1355 2.135 .984 .016

1215 2845.67 3 8,537 8667 -.970 .166 .166 8537.00 1 8,537 2946 -.537 .296 .296

1216 2523.40 10 25,234 137956 .512 .696 .305 6308.50 4 25,234 49749 -.049 .480 .480

1217 226.38 58 13,130 382211 .050 .520 .480 423.55 31 13,130 177984 -1.210 .113 .113

1218 204.31 16 3,269 29936 1.003 .842 .158 363.22 9 3,269 21112 2.261 .988 .012

1219 218.13 90 19,632 979703 1.791 .963 .037 370.42 53 19,632 571886 1.252 .895 .105

1220 4182.80 5 20,914 57586 .393 .653 .347 5228.50 4 20,914 43822 .165 .566 .434

1221 534.27 11 5,877 30095 -.396 .346 .346 839.57 7 5,877 21276 .157 .563 .437

1222 -- -- -- -- -- -- -- -- -- -- -- -- -- --

1223 152.11 36 5,476 105466 .727 .766 .234 210.62 26 5,476 77638 .800 .788 .212

1224 282.57 7 1,978 8415 .988 .838 .162 659.33 3 1,978 2380 -.594 .276 .276

1225 203.77 13 2,649 16711 -.184 .427 .427 331.13 8 2,649 10808 .098 .539 .461

1226 1684.69 13 21,901 146388 .177 .570 .430 3650.17 6 21,901 69794 .264 .604 .396

1227 347.00 18 6,246 75164 2.477 .993 .007 567.82 11 6,246 45037 1.787 .963 .037

1228 343.43 73 25,070 972888 .935 .825 .175 642.82 39 25,070 496639 .172 .568 .432

1229 155.39 95 14,762 716042 .358 .640 .360 268.40 55 14,762 440758 1.101 .865 .135

1230 163.18 88 14,360 695829 1.646 .950 .050 251.93 57 14,360 451990 1.365 .914 .086

1231 155.80 5 779 2255 .612 .730 .270 779.00 1 779 734 1.532 .937 .063

1232 243.75 4 975 2936 1.752 .960 .040 487.50 2 975 1604 1.580 .943 .057

1233 212.92 25 5,323 86872 2.647 .996 .004 443.58 12 5,323 39715 1.461 .928 .072

1234 413.48 27 11,164 142152 -.511 .305 .305 858.77 13 11,164 74305 .150 .560 .440

1235 318.46 13 4,140 35446 1.981 .976 .024 460.00 9 4,140 25483 1.911 .972 .028

1236 246.22 9 2,216 6053 -2.042 .021 .021 554.00 4 2,216 3414 -.796 .213 .213

1237 398.24 33 13,142 142036 -3.433 0 0 773.06 17 13,142 69043 -2.728 .003 .003

1238 314.49 81 25,474 1057702 .393 .653 .347 621.32 41 25,474 514041 -.174 .431 .431

1239 218.10 69 15,049 507125 -.334 .369 .369 429.97 35 15,049 253906 -.368 .357 .357

1240 938.50 2 1,877 1963 .112 .545 .455 1877.00 1 1,877 114 -1.522 .064 .064

1241 192.26 94 18,072 874499 .497 .690 .310 340.98 53 18,072 484280 .141 .556 .444

1242 149.40 5 747 2728 1.785 .963 .037 186.75 4 747 2095 1.394 .918 .082

1243 133.36 132 17,604 1216998 .944 .827 .173 220.05 80 17,604 743075 .856 .804 .196

1244 191.52 100 19,152 919624 -.687 .246 .246 336.00 57 19,152 516696 -.698 .243 .243

1245 677.07 28 18,958 338497 2.524 .994 .006 1184.88 16 18,958 169542 0.817 .793 .207

1246 578.00 4 2,312 5221 .447 .673 .327 1156.00 2 2,312 2159 -.162 .436 .436

1247 379.55 40 15,182 285733 -.646 .259 .259 1167.85 13 15,182 89613 -.574 .283 .283

1248 -- -- -- -- -- -- -- -- -- -- -- -- -- --

Table 7. Summary of interoccurrence intervals for daily precipitation thresholds of 2.5 and 3.0 inches—Continued

Seq.

no.

Daily precipitation threshold of 2.5 inches and greater Daily precipitation threshold of 3.0 inches and greater

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue
196 Atlas of Interoccurrence Intervals for Selected Thresholds of Daily Precipitation in Texas 

1249 397.65 31 12,327 215783 1.247 .894 .106 684.83 18 12,327 125561 .968 .833 .167

1250 244.09 151 36,857 2916702 1.025 .847 .153 433.61 85 36,857 1672926 1.086 .861 .139

1251 554.00 2 1,108 376 -1.618 .053 .053 -- -- -- -- -- -- --

1252 295.58 120 35,470 2315709 1.672 .953 .047 485.89 73 35,470 1331601 .422 .664 .336

1253 171.73 26 4,465 64847 1.035 .850 .150 235.00 19 4,465 44201 .317 .625 .375

1254 76.00 6 456 1547 .555 .711 .289 114.00 4 456 1156 .927 .823 .177

1255 161.78 83 13,428 575057 .504 .693 .307 248.67 54 13,428 354738 -.275 .392 .392

1256 511.83 40 20,473 513170 2.775 .997 .003 1023.65 20 20,473 252057 1.791 .963 .037

1257 300.45 65 19,529 621850 -.283 .389 .389 610.28 32 19,529 297521 -.469 .320 .320

1258 213.71 17 3,633 39671 2.033 .979 .021 259.50 14 3,633 31785 1.619 .947 .053

1259 -- -- -- -- -- -- -- -- -- -- -- -- -- --

1260 170.19 128 21,784 1458245 .901 .816 .184 262.46 83 21,784 915818 .206 .582 .418

1261 408.95 20 8,179 96332 1.377 .916 .084 629.15 13 8,179 63950 1.267 .897 .103

1262 192.33 6 1,154 2720 -.909 .182 .182 288.50 4 1,154 1831 -.716 .237 .237

1263 -- -- -- -- -- -- -- -- -- -- -- -- -- --

1264 516.00 3 1,548 3023 .906 .817 .183 516.00 3 1,548 3023 .906 .817 .183

1265 164.48 21 3,454 46506 2.241 .987 .013 265.69 13 3,454 24418 .547 .708 .292

1266 288.55 66 19,044 640492 .270 .606 .394 577.09 33 19,044 302447 -.373 .355 .355

1267 354.84 38 13,484 245465 -.447 .327 .327 612.91 22 13,484 151423 .170 .567 .433

1268 295.88 58 17,161 527220 .783 .783 .217 536.28 32 17,161 310459 1.280 .900 .100

1269 -- -- -- -- -- -- -- -- -- -- -- -- -- --

1270 729.00 3 2,187 3485 .187 .574 .426 2187.00 1 2,187 1200 .169 .567 .433

1271 398.56 88 35,073 1388710 -1.627 .052 .052 687.71 51 35,073 719695 -2.416 .008 .008

1272 1330.33 3 3,991 6121 .067 .527 .473 1330.33 3 3,991 6121 .067 .527 .473

1273 560.53 17 9,529 105729 2.181 .985 .015 1191.13 8 9,529 49648 1.482 .931 .069

1274 128.19 48 6,153 147944 .022 .509 .491 246.12 25 6,153 67189 -1.095 .137 .137

1275 103.03 35 3,606 66278 .515 .697 .303 171.71 21 3,606 40439 .540 .705 .295

1276 115.15 48 5,527 137757 .462 .678 .322 157.91 35 5,527 94446 -.241 .405 .405

1277 111.30 23 2,560 36897 2.104 .982 .018 134.74 19 2,560 29283 1.541 .938 .062

1278 194.48 149 28,977 2423132 2.589 .995 .005 329.28 88 28,977 1420842 1.859 .968 .032

1279 1501.00 1 1,501 58 -1.598 .055 .055 -- -- -- -- -- -- --

1280 336.19 16 5,379 43418 .062 .525 .475 768.43 7 5,379 22756 .957 .831 .169

1281 206.77 30 6,203 95351 .235 .593 .407 344.61 18 6,203 64149 1.095 .863 .137

1282 -- -- -- -- -- -- -- -- -- -- -- -- -- --

1283 581.44 9 5,233 23178 -.082 .467 .467 654.13 8 5,233 18016 -.683 .248 .248

1284 137.59 71 9,769 374594 1.170 .879 .121 191.55 51 9,769 265036 .791 .785 .215

1285 1754.67 12 21,056 149096 1.081 .860 .140 3509.33 6 21,056 70656 .503 .692 .308

1286 179.36 102 18,295 980652 .893 .814 .186 425.47 43 18,295 426480 .957 .831 .169

1287 398.67 15 5,980 51168 .945 .828 .172 664.44 9 5,980 32877 1.152 .875 .125

1288 401.60 30 12,048 165417 -.803 .211 .211 602.40 20 12,048 99184 -1.369 .086 .086

1289 462.27 30 13,868 185918 -1.008 .157 .157 1260.73 11 13,868 63165 -.987 .162 .162

1290 476.67 3 1,430 2555 .573 .717 .283 715.00 2 1,430 1563 .228 .590 .410

1291 405.33 3 1,216 2619 1.308 .904 .096 608.00 2 1,216 1855 1.287 .901 .099

1292 182.08 108 19,665 1193196 2.225 .987 .013 289.19 68 19,665 788886 2.569 .995 .005

1293 274.86 62 17,041 518491 -0.253 .400 .400 355.02 48 17,041 411421 0.072 .529 .471

1294 389.08 13 5,058 28330 -.864 .194 .194 843.00 6 5,058 13335 -.514 .304 .304

1295 212.67 3 638 868 -.279 .390 .390 -- -- -- -- -- -- --

1296 101.36 42 4,257 85557 -.482 .315 .315 202.71 21 4,257 48610 .695 .756 .244

Table 7. Summary of interoccurrence intervals for daily precipitation thresholds of 2.5 and 3.0 inches—Continued

Seq.

no.

Daily precipitation threshold of 2.5 inches and greater Daily precipitation threshold of 3.0 inches and greater

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue
Table 7 197

1297 208.39 13 2,709 14316 -1.168 .122 .122 270.90 10 2,709 8852 -1.898 .029 .029

1298 185.63 8 1,485 7340 1.155 .876 .124 742.50 2 1,485 1184 -.497 .310 .310

1299 158.95 61 9,696 352693 2.606 .995 .005 269.33 36 9,696 208726 2.036 .979 .021

1300 -- -- -- -- -- -- -- -- -- -- -- -- -- --

1301 181.61 153 27,787 2128759 .031 .512 .488 323.11 86 27,787 1233564 .521 .699 .301

1302 201.02 93 18,695 946786 1.489 .932 .068 327.98 57 18,695 593482 1.489 .932 .068

1303 291.00 1 291 228 .982 .837 .163 -- -- -- -- -- -- --

1304 303.33 12 3,640 25576 1.026 .848 .152 606.67 6 3,640 15251 1.683 .954 .046

1305 11327.50 2 22,655 23673 .110 .544 .456 11327.50 2 22,655 23673 .110 .544 .456

1306 383.90 39 14,972 273400 -.687 .246 .246 712.95 21 14,972 122454 -1.755 .040 .040

Table 7. Summary of interoccurrence intervals for daily precipitation thresholds of 2.5 and 3.0 inches—Continued

Seq.

no.

Daily precipitation threshold of 2.5 inches and greater Daily precipitation threshold of 3.0 inches and greater

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue

Mean

interoccurrence

interval

(days)

Total

no. of

events

Total

no. of

days

available

Sigma

S

Standard

normal

variate

Nonexceedance

probability

pvalue
198 Atlas of Interoccurrence Intervals for Selected Thresholds of Daily Precipitation in Texas 

Table 9

Table 8

Table 8. Example computation steps of interoccurrence intervals for a Poisson process described in text

[Total time, T, is 60 days and mean interoccurrence interval, Λ, is 10 days. Median number of occurrences to closest integer is 

5 (shaded row)] 

Table 9. Summary of statewide interoccurrence interval statistics and diagnostic statistics of interoccurrence 

interval maps

[RMSE, root-mean-square error; bias computed as observed value for station minus value predicted from map; in., inches] 

No. of

occurrences

Probability

density value,

eq. 5

Cumulative

probability,

eq. 6

0 .00248 .00248

1 .0149 .0174

2 .0466 .0620

3 .0892 .151

4 .134 .285

5 .161 .446

6 .161 .606

7 .138 .744

8 .103 .847

9 .0688 .916

10 .0413 .957

Daily

precipitation

threshold

(in.)

Statewide

mean

interoccurrence

interval

(days)

Statewide

standard

deviation

of

interoccurrence

interval

(days)

Statewide

no. of

stations

with

events

Statewide

no. of

p-values

less

than

or equal

to .01

Percent of

stations

with

p-values

less than

or equal

to .01

Statewide

mean

of interpolated

interoccurrence

interval

map

(days)

Statewide

mean

bias of

interoccurrence

interval

map

(days)

RMSE

of

interoccurrence

interval

map

(days)

Percent

change

from

standard

deviation

to

RMSE

(percent)

0.05 8.04 3.68 1,299 406 31.3 7.64 0.404 2.80 -24

.10 9.38 4.02 1,299 309 23.8 8.95 .436 2.73 -32

.25 14.03 7.70 1,298 184 14.2 13.4 .679 5.20 -32

.50 23.50 18.86 1,294 171 13.2 22.3 1.22 13.7 -27

.75 36.76 29.83 1,284 151 11.8 35.5 1.27 17.8 -40

1.0 55.72 52.12 1,277 140 11.0 54.5 1.23 29.5 -43

1.5 127.7 160.1 1,258 107 8.51 123 5.20 86.5 -46

2.0 273.0 458.0 1,230 87 7.07 268 5.23 183 -60

2.5 533.9 882.0 1,189 65 5.47 528 5.78 416 -53

3.0 876.3 1,515 1,143 37 3.24 864 12.0 999 -34

n f

n( ) T Fn( ) T
Table 11 199

Table 11

Table 10

Table 10. Summary of interoccurrence ratios by month for 0.05-inch and greater daily precipitation threshold

[A monthly interoccurrence ratio is defined as ratio of mean interoccurrence interval for corresponding month to mean 

interoccurrence interval for period of record at the station. Mean monthly interoccurrence ratio is arithmetic average of 

monthly ratios for all stations, and median monthly interoccurrence ratio is median of monthly ratios for all stations. Adjusted 

ratios have averages of unity and therefore are preferred because statistical bias has been removed.]

Table 11. Summary of interoccurrence ratios by month for 0.10-inch and greater daily precipitation threshold

[A monthly interoccurrence ratio is defined as ratio of mean interoccurrence interval for corresponding month to mean 

interoccurrence interval for period of record at the station. Mean monthly interoccurrence ratio is arithmetic average of 

monthly ratios for all stations, and median monthly interoccurrence ratio is median of monthly ratios for all stations. Adjusted 

ratios have averages of unity and therefore are preferred because statistical bias has been removed.]

Month

Mean monthly

interoccurrence

ratio

Median monthly

interoccurrence

ratio

Adjusted

mean monthly

interoccurrence

ratio

Adjusted

median monthly

interoccurrence

ratio

Jan. 1.21 1.08 1.12 1.07

Feb. 1.13 .99 1.04 .98

Mar. 1.20 1.10 1.11 1.09

Apr. 1.16 1.04 1.07 1.03

May .88 .81 .79 .80

June .84 .82 .75 .81

July 1.07 1.06 .98 1.05

Aug. 1.15 1.14 1.06 1.13

Sept. .91 .88 .82 .87

Oct. 1.09 1.05 1.00 1.04

Nov. 1.11 1.04 1.02 1.03

Dec. 1.28 1.12 1.19 1.11

Average 1.09 1.01

Incremental adjustment -.09 -.01

Month

Mean monthly

interoccurrence

ratio

Median monthly

interoccurrence

ratio

Adjusted

mean monthly

interoccurrence

ratio

Adjusted

median monthly

interoccurrence

ratio

Jan. 1.25 1.13 1.15 1.11

Feb. 1.21 1.05 1.11 1.03

Mar. 1.24 1.14 1.14 1.12

Apr. 1.19 1.06 1.09 1.04

May .88 .80 .78 .78

June .81 .78 .71 .76

July 1.05 1.04 .95 1.02

Aug. 1.14 1.15 1.04 1.13

Sept. .91 .87 .81 .85

Oct. 1.06 1.03 .96 1.01

Nov. 1.10 1.04 1.00 1.02

Dec. 1.30 1.14 1.20 1.12

Average 1.10 1.02

Incremental adjustment -.10 -.02
200 Atlas of Interoccurrence Intervals for Selected Thresholds of Daily Precipitation in Texas 

Table 13

Table 12

Table 12. Summary of interoccurrence ratios by month for 0.25-inch and greater daily precipitation threshold

[A monthly interoccurrence ratio is defined as ratio of mean interoccurrence interval for corresponding month to mean 

interoccurrence interval for period of record at the station. Mean monthly interoccurrence ratio is arithmetic average of 

monthly ratios for all stations, and median monthly interoccurrence ratio is median of monthly ratios for all stations. Adjusted 

ratios have averages of unity and therefore are preferred because statistical bias has been removed.]

Table 13. Summary of interoccurrence ratios by month for 0.50-inch and greater daily precipitation threshold

[A monthly interoccurrence ratio is defined as ratio of mean interoccurrence interval for corresponding month to mean 

interoccurrence interval for period of record at the station. Mean monthly interoccurrence ratio is arithmetic average of 

monthly ratios for all stations, and median monthly interoccurrence ratio is median of monthly ratios for all stations. Adjusted 

ratios have averages of unity and therefore are preferred because statistical bias has been removed.]

Month

Mean monthly

interoccurrence

ratio

Median monthly

interoccurrence

ratio

Adjusted

mean monthly

interoccurrence

ratio

Adjusted

median monthly

interoccurrence

ratio

Jan. 1.40 1.24 1.28 1.21

Feb. 1.38 1.18 1.26 1.15

Mar. 1.42 1.23 1.30 1.20

Apr. 1.23 1.07 1.11 1.04

May .88 .78 .76 .75

June .76 .73 .64 .70

July 1.01 1.00 .89 .97

Aug. 1.13 1.12 1.00 1.09

Sept. .90 .86 .78 .83

Oct. 1.00 .97 .88 .94

Nov. 1.08 1.02 .96 .99

Dec. 1.25 1.13 1.13 1.10

Average 1.12 1.03

Incremental adjustment -.12 -.028

Month

Mean monthly

interoccurrence

ratio

Median monthly

interoccurrence

ratio

Adjusted

mean monthly

interoccurrence

ratio

Adjusted

median monthly

interoccurrence

ratio

Jan. 1.44 1.30 1.31 1.26

Feb. 1.50 1.32 1.37 1.28

Mar. 1.52 1.33 1.39 1.29

Apr. 1.32 1.15 1.19 1.11

May .90 .78 .77 .74

June .74 .69 .61 .65

July .96 .94 .83 .90

Aug. 1.11 1.09 .98 1.05

Sept. .92 .88 .79 .84

Oct. .94 .91 .81 .87

Nov. 1.05 .98 .92 .94

Dec. 1.19 1.11 1.06 1.07

Average 1.13 1.04

Incremental adjustment -.13 -.040
Table 15 201

Table 15

Table 14

Table 14. Summary of interoccurrence ratios by month for 0.75-inch and greater daily precipitation threshold

[A monthly interoccurrence ratio is defined as ratio of mean interoccurrence interval for corresponding month to mean 

interoccurrence interval for period of record at the station. Mean monthly interoccurrence ratio is arithmetic average of 

monthly ratios for all stations, and median monthly interoccurrence ratio is median of monthly ratios for all stations. Adjusted 

ratios have averages of unity and therefore are preferred because statistical bias has been removed.]

Table 15. Summary of interoccurrence ratios by month for 1.0-inch and greater daily precipitation threshold

[A monthly interoccurrence ratio is defined as ratio of mean interoccurrence interval for corresponding month to mean 

interoccurrence interval for period of record at the station. Mean monthly interoccurrence ratio is arithmetic average of 

monthly ratios for all stations, and median monthly interoccurrence ratio is median of monthly ratios for all stations. Adjusted 

ratios have averages of unity and therefore are preferred because statistical bias has been removed.]

Month

Mean monthly

interoccurrence

ratio

Median monthly

interoccurrence

ratio

Adjusted

mean monthly

interoccurrence

ratio

Adjusted

median monthly

interoccurrence

ratio

Jan. 1.41 1.31 1.29 1.27

Feb. 1.47 1.35 1.35 1.31

Mar. 1.54 1.38 1.42 1.34

Apr. 1.36 1.24 1.24 1.20

May .95 .84 .83 .80

June .75 .69 .63 .65

July .93 .90 .81 .86

Aug. 1.08 1.06 .96 1.02

Sept. .92 .88 .80 .84

Oct. .89 .86 .77 .82

Nov. 1.01 .95 .89 .91

Dec. 1.10 1.05 .98 1.01

Average 1.12 1.043

Incremental adjustment -.12 -.043

Month

Mean monthly

interoccurrence

ratio

Median monthly

interoccurrence

ratio

Adjusted

mean monthly

interoccurrence

ratio

Adjusted

median monthly

interoccurrence

ratio

Jan. 1.35 1.27 1.26 1.24

Feb. 1.38 1.32 1.29 1.29

Mar. 1.47 1.36 1.38 1.33

Apr. 1.36 1.29 1.27 1.26

May 1.01 .92 .92 .89

June .79 .73 .70 .70

July .90 .86 .81 .83

Aug. 1.07 1.03 .98 1.00

Sept. .90 .86 .81 .83

Oct. .84 .81 .75 .78

Nov. .95 .91 .86 .88

Dec. 1.02 .97 .93 .94

Average 1.09 1.03

Incremental adjustment -.09 -.03
202 Atlas of Interoccurrence Intervals for Selected Thresholds of Daily Precipitation in Texas 

Table 17

Table 16

Table 16. Summary of interoccurrence ratios by month for 1.5-inch and greater daily precipitation threshold

[A monthly interoccurrence ratio is defined as ratio of mean interoccurrence interval for corresponding month to mean 

interoccurrence interval for period of record at the station. Mean monthly interoccurrence ratio is arithmetic average of 

monthly ratios for all stations, and median monthly interoccurrence ratio is median of monthly ratios for all stations. Adjusted 

ratios have averages of unity and therefore are preferred because statistical bias has been removed.]

Table 17. Summary of interoccurrence ratios by month for 2.0-inch and greater daily precipitation threshold

[A monthly interoccurrence ratio is defined as ratio of mean interoccurrence interval for corresponding month to mean 

interoccurrence interval for period of record at the station. Mean monthly interoccurrence ratio is arithmetic average of 

monthly ratios for all stations, and median monthly interoccurrence ratio is median of monthly ratios for all stations. Adjusted 

ratios have averages of unity and therefore are preferred because statistical bias has been removed.]

Month

Mean monthly

interoccurrence

ratio

Median monthly

interoccurrence

ratio

Adjusted

mean monthly

interoccurrence

ratio

Adjusted

median monthly

interoccurrence

ratio

Jan. 1.17 1.06 1.13 1.06

Feb. 1.16 1.12 1.12 1.12

Mar. 1.37 1.30 1.33 1.30

Apr. 1.30 1.25 1.26 1.25

May 1.07 1.01 1.03 1.01

June .89 .85 .85 .85

July .92 .88 .88 .88

Aug. 1.02 .99 .98 .99

Sept. .90 .87 .86 .87

Oct. .79 .77 .75 .77

Nov. .92 .87 .88 .87

Dec. .94 .86 .90 .86

Average 1.04 .99

Incremental adjustment -.04 0

Month

Mean monthly

interoccurrence

ratio

Median monthly

interoccurrence

ratio

Adjusted

mean monthly

interoccurrence

ratio

Adjusted

median monthly

interoccurrence

ratio

Jan. 1.06 .93 1.06 .99

Feb. 1.00 .92 1.00 .98

Mar. 1.30 1.20 1.30 1.26

Apr. 1.21 1.15 1.21 1.21

May 1.05 1.03 1.05 1.09

June .92 .89 .92 .95

July .96 .89 .96 .95

Aug. 1.02 .95 1.02 1.01

Sept. .92 .88 .92 .94

Oct. .80 .76 .80 .82

Nov. .95 .86 .95 .92

Dec. .88 .79 .88 .85

Average 1.01 .94

Incremental adjustment 0 .06
Table 19 203

Table 19

Table 18

Table 18. Summary of interoccurrence ratios by month for 2.5-inch and greater daily precipitation threshold

[A monthly interoccurrence ratio is defined as ratio of mean interoccurrence interval for corresponding month to mean 

interoccurrence interval for period of record at the station. Mean monthly interoccurrence ratio is arithmetic average of 

monthly ratios for all stations, and median monthly interoccurrence ratio is median of monthly ratios for all stations. Adjusted 

ratios have averages of unity and therefore are preferred because statistical bias has been removed.]

Table 19. Summary of interoccurrence ratios by month for 3.0-inch and greater daily precipitation threshold

[A monthly interoccurrence ratio is defined as ratio of mean interoccurrence interval for corresponding month to mean 

interoccurrence interval for period of record at the station. Mean monthly interoccurrence ratio is arithmetic average of 

monthly ratios for all stations, and median monthly interoccurrence ratio is median of monthly ratios for all stations. Adjusted 

ratios have averages of unity and therefore are preferred because statistical bias has been removed.]

Month

Mean monthly

interoccurrence

ratio

Median monthly

interoccurrence

ratio

Adjusted

mean monthly

interoccurrence

ratio

Adjusted

median monthly

interoccurrence

ratio

Jan. 1.04 .85 1.04 .95

Feb. .94 .80 .94 .90

Mar. 1.24 1.08 1.24 1.18

Apr. 1.19 1.09 1.19 1.19

May 1.02 .99 1.02 1.09

June .97 .93 .97 1.03

July .95 .88 .95 .98

Aug. 1.00 .89 1.00 .99

Sept. .91 .88 .91 .98

Oct. .80 .76 .80 .86

Nov. .91 .83 .91 .93

Dec. .87 .78 .87 .88

Average .99 .90

Incremental adjustment .01 .10

Month

Mean monthly

interoccurrence

ratio

Median monthly

interoccurrence

ratio

Adjusted

mean monthly

interoccurrence

ratio

Adjusted

median monthly

interoccurrence

ratio

Jan. .98 .74 1.01 .89

Feb. .90 .70 .93 .85

Mar. 1.15 1.01 1.18 1.16

Apr. 1.12 1.01 1.15 1.16

May .99 .93 1.02 1.08

June .94 .88 .97 1.03

July .96 .82 .99 .97

Aug. 1.01 .89 1.04 1.04

Sept. .91 .86 .94 1.01

Oct. .83 .79 .86 .94

Nov. .91 .81 .94 .96

Dec. .94 .77 .97 .92

Average .97 .85

Incremental adjustment .03 .15
204 Atlas of Interoccurrence Intervals for Selected Thresholds of Daily Precipitation in Texas 

Table 20

Table 20. Regional estimates of mean interoccurrence interval of precipitation for Austin, Texas

[Regional mean interoccurrence intervals estimated from figures 4–13. For comparison, site-specific mean interoccurrence 

intervals for 72-year record for Austin Camp Mabry (station no. 428, sequence no. 46) are listed as well as those for 18-year 

record for Austin Dam (station no. 430, sequence no. 47).]

Daily

precipitation

threshold

(inches)

Regional

mean

interoccurrence

interval

(days)

Station 428

sitespecific

mean

interoccurrence

interval

(days)

Station 430

sitespecific

mean

interoccurrence

interval

(days)

0.05 6.6 5.96 6.55

.10 7.8 7.37 8.03

.25 11.3 11.06 12.60

.50 17.5 17.66 20.20

.75 26 26.01 28.41

1.0 36 37.41 42.42

1.5 79 76.04 79.54

2.0 150 146.89 159.08

2.5 265 251.00 254.52

3.0 440 403.95 454.20