Precipitation in the Northern Plains, 

September 1996 through April1997 

Circular 1185-A 

U.S. Department of the Interior 

U.S. Geological Survey 
Cover photograph: Farmstead and stranded car in rural Bath, 

South Dakota, January 22, 1997. Photograph by John Davis, 

Aberdeen American News. 
Precipitation in the Northern Plains, 

September 1996 through April 1997 

By Kathleen M. Macek-Rowland, Michael J. Burr, and 

Gregory B. Mitton 

U.S. GEOLOGICAL SURVEY CIRCULAR 1185-A 
U.S. DEPARTMENT OF THE INTERIOR 

GALE A. NORTON, Secretary 

U.S. GEOLOGICAL SURVEY 

Charles G. Groat, Director 

The use of firm, trade, and brand names in this report is for identification purposes only and 

does not constitute endorsement by the U.S. Government 

U.S. GOVERNMENT PRINTING OFFICE: 2001 

Free on application to the 

U.S. Geological Survey 

Branch of Information Services 

Box 25286 

Denver, CO 80225-0286 

Library of Congress Cataloging-in-Publications Data 

Macek-Rowland, Kathleen. 

Precipitation in the northern plains, September 1996 through April 1997 I by Kathleen 

M. Macek-Rowland, Michael J. Burr, and Gregory B. Mitton. 

p. em. - (U.S. Geological Survey circular ; 1185-A) 

Includes bibliographical references. 

1. Precipitation (Meteorology)-Middle West-Observations. I. Burr, Michael J. II 

Mitton, Gregory B. III. Title. IV. Series. 

QC925.1.U8 M636 2000 

551.57'7277-dc21 00-045456 

ISBN 0-607-96338-7 
FOREWORD 

Floods are a common occurrence on all major streams and rivers of the 

United States. Many floods are just a minor nuisance when low-lying fields and 

roads are inundated; however, major floods that result in loss of life and extensive 

damage occur on a number of the Nation's rivers each year. Know ledge of the 

flood characteristics of the Nation's streams and rivers is important for preventing 

the loss of life and mitigating the ever-increasing costs of flood damages. 

The U.S. Geological Survey (USGS) plays a critical role in supporting 

flood mitigation, flood forecasting, and response and recovery efforts during and 

after floods. The 18,000 streamflow-gaging stations that have been operated by 

the USGS at some time since 1889 provided much of the base information for 

assessing flood risk and for designing infrastructure such as dams and levees that 

minimize flood damages. The streamflow-gaging stations also provide data that 

are critical to effective management of the Nation's water resources. 

The USGS has a current network of 7,000 streamflow-gaging stations. Of 

these stations, 4,200 are used to provide real-time streamflow data 24 hours a day 

directly to the public and many organizations, including the National Weather 

Service, U.S. Army Corps of Engineers, the Bureau of Reclamation, and the 

Federal Emergency Management Agency. These and other Federal, State, and 

local agencies use the river-stage data to forecast river conditions, to issue flood 

warnings and river-conditions statements, to plan flood response and recovery 

operations, and to plan reservoir releases or water withdrawals. With the advent 

of the internet, USGS data, real-time and historical, are being disseminated to 

an even broader range of interested users worldwide. 

This report, "Precipitation in the Northern Plains, September 1996 through 

April 1997 ," is an example of the type of information produced by the USGS 

streamflow-gaging network. The report is the first in a two-part series of reports that 

document the 1997 spring floods in the northern plains. The report describes precipitation and climatic conditions before and during the floods. U.S. Geological Survey 

Circular 1185-B, "Peak Discharges and Flow Volumes for Streams in the Northern 

Plains, 1996-97 ," is the second in the two-part series of reports and presents the 

magnitude and duration of discharges and volumes, describes the effects of 

reservoir storage on flood peaks, and summarizes the effects of the 1997 spring 

floods on the people of the northern plains. 

Robert M. Hirsch 

Chief Hydrologist 

FOREWORD Ill 

CONTENTS 

Foreword . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . III 

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

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

General Climatology.............................................................................................................................................................. 3 

Precipitation........................................................................................................................................................................... 4 

Fall Precipitation (September through October 1996) .. ... . . . . . .. ..... ........ ................... ...... .. . . . . .............. ................. .......... 4 

Winter Precipitation (November 1996 through March 1997)...................................................................................... 9 

Spring Precipitation (April1997) ................................................................................................................................ 11 

Analysis of Selected Storms.................................................................................................................................................. 13 

December 16-18, 1996............................................................. .. . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . ... . . . . 14 

January 4-5, 1997 ........................................................................................................................................................ 15 

April 5-6, 1997 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . 16 

Chronological Overview........................................................................................................................................................ 16 

References.............................................................................................................................................................................. 19 

FIGURES 

1. Map showing general area of flooding streams, spring 1997, and locations of selected 

weather stations........................................................................................................................................................... 2 

2. Map and graphs showing monthly precipitation at 10 weather stations in the northern plains 

during September 1996 through April1997 and 30-year precipitation normals for September 

through April 1961-90.......................... .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . ... . . . . . . . . . . . .. . . . . . . . . . . . . . .. . . . . . . . . . . . . . . .. . . . . . . . . . . 7 

3. Map showing areal distribution of precipitation, in inches, for the nmthern plains, September 

through October 1996 . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . .. . . . . . . . . . . . . 8 

4. Map showing areal distribution of precipitation, in percent of 30-year precipitation normal, 

for the northern plains, September through October 1961-90 . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ... . . . . . . . . . . 9 

5. Map showing areal distribution of snowfall, in inches, for the northern plains, November 1996 

through April 1997.............................. .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . 11 

6. Map and graphs showing cumulative snowfall at six weather stations in the northern plains, 

November 1996 through April 1997 . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 

7. Map showing average weather patterns over the northern plains, December 16-18, 1996........................................ 14 

8. Map showing average weather patterns over the northern plains, January 4-5, 1997 ................................................ 15 

9. Map showing average weather patterns over the northern plains, April 5-6, 1997..................... .. . . . . . . . . . . . . .. . . . . . . . . . . . . . . . 17 

TABLES 

1. Monthly precipitation at 10 weather stations in the northern plains during September 1996 

through April1997 and 30-year precipitation normals for September through April1961-90 ............................. 5 

2. The five greatest September through October precipitation totals, September through 

October 1996 precipitation totals, and means for the period of record at six weather stations 

in the northern plains . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ... . . 10 

CONVERSION FACTORS 

Multiply 

inch 

mile 

By 

2.54 

1.609 

To obtain 

centimeter 

kilometer 

Degree Fahrenheit (°F) may be converted to degree Celsius (°C) by using the following equation: 

°C = 5/9 (°F- 32) 

CONTENTS V 

Precipitation in the Northern Plains, 

September 1996 through April 1997 

By Kathleen M. Macek-Rowland, Michael J. Burr, and Gregory B. Mitton 

Abstract 

Excessive precipitation during the fall 

and winter of 1996-97 produced record floods 

that devastated many communities along rivers 

and streams in parts of the Red River of the 

North, Missouri River, and upper Mississippi 

River Basins. Above-normal snowfall throughout 

the winter of 1996-97, combined with excessive 

precipitation during the fall of 1996 and additional moisture from a spring blizzard on 

April 5-6, 1997, caused the worst flooding 

in several areas in more than 100 years. 

During September 1996, monthly 

precipitation at 6 of 10 weather stations in 

the northern plains was above normal. During 

October 1996, monthly precipitation at 7 of the 

10 stations was above normal. Precipitation was 

more than 200 percent of normal at three stations 

in September and two stations in October. 

During November 1996 through 

March 1997, no less than 3 and as many as 9 

of the 10 weather stations received above-normal 

precipitation in any 1 month. Precipitation was 

more than 200 percent of normal at many of the 

stations and 376 percent of normal at one station. 

This excessive precipitation resulted, in part, from 

record snowfalls at 4 of the 10 weather stations in 

the region. At 3 other weather stations, snowfall 

totals ranked in the top 10 highest snowfalls for 

the period of record at that station. 

The above-normal fall precipitation, 

frozen moist soils, and record snowfall over most 

of the northern plains resulted in peak streamflows on many rivers and streams in central and 

eastern North Dakota, western Minnesota, and 

central and eastern South Dakota. A storm 

on April 5-6, 1997, aggravated already serious 

flooding. Floodwaters and severe weather forced 

thousands of people to flee their homes, some 

permanently, and caused more than $2 billion 

in damages to the region. For the people of the 

northern plains, the winter of 1996-97, combined 

with the 1997 spring floods, was one of the worst 

natural disasters in recent history. 

INTRODUCTION 

Flooding in the northern plains usually is 

caused by spring snowmelt. The severity of the 

flooding is affected by (1) high soil-moisture levels 

produced by substantial precipitation in the fall; 

(2) above-normal snowfall in the winter; (3) frozen 

moist soils that prohibit infiltration of moisture; 

(4) a late spring thaw; (5) above-normal precipitation 

during the spring thaw; and (6) ice jams (temporary 

dams of ice) on rivers and streams. Many of these 

conditions were present in the northern plains before 

and during the 1997 spring floods. This report, 

one of two reports that document the spring floods 

in the northern plains, describes precipitation during 

September 1996 through April 1997 in parts of the 

Red River of the North, upper Mississippi River, 

and Missouri River Basins1 (fig. 1). These basins are 

located in central and eastern North Dakota, western 

Minnesota, and central and eastern South Dakota. 

1

U.S. Geological Survey Circular 1185-B, "Peak Discharges 

and Flow Volumes for Streams in the Northern Plains, 1996-97," 

by Kathleen M. Macek-Rowland, Michael J. Burr, and Gregory B. 

Mitton, describes peak discharges and flow volumes for streams in 

parts of the Red River of the North, upper Mississippi River, and 

Missouri River Basins. 

Abstract 
Base from U.S. Geological Survey 

1 :2,000,000, 1972 

0 40 80 

EXPLANATION 

D Red Ri ver of the North Basin 

D Upper Mississippi River Basin 

D Minnesota Ri ver Basin 

D Missouri Ri ver Basin 

U James River Basin 

[J Big Sioux Ri ver Basin 

D Area of flooding streams 

~ Weather station 

Figure 1. General area of flooding streams, spring 1997, and locations of selected weather stations. 

2 Precipitation in the Northern Plains, September 1996 through April 1997 

120 MILES 
In the northern plains, precipitation during 

September and October 1996 occurred as rain, 

and precipitation during November 1996 through 

April 1997 occurred as snow during several winter 

storms or blizzards. Snowfall totals in many areas 

were 200 to 300 percent above normal for the winter. 

The above-normal snowfall closed schools and 

businesses and blocked major roads several times 

throughout the winter. The accumulated snowfall, 

combined with excessive precipitation during the fall 

of 1996 and additional moisture from a spring blizzard 

on April 5-6, 1997, caused the worst flooding in 

several areas in more than 100 years. The floodwaters 

and severe weather forced thousands of people to flee 

their homes, some permanently, and caused more than 

$2 billion in damages to the region. 

This report provides a general overview of 

the unusually excessive precipitation that occurred 

during the fall and winter of 1996-97. A general overview of precipitation during the 8 months from 

September 1996 through April 1997 is presented 

along with an analysis of monthly precipitation at 

10 weather stations in the flood-affected region. 

Weather patterns associated with three specific snowstorm systems and the resulting snowfall totals are 

shown as examples of storms that occurred throughout 

the region during those 8 months. 

The U.S. Geological Survey, one of the principal Federal agencies responsible for the collection 

and interpretation of water-resources data, works with 

other Federal, State, and local agencies to ensure the 

data are made available in an accurate and timely 

manner. This report represents the combined efforts 

of U.S. Geological Survey personnel and individuals 

from other agencies, particularly the National Weather 

Service and State climatology offices. 

GENERAL CLIMATOLOGY 

North Dakota, Minnesota, and South Dakota 

have a typical continental climate characterized by 

warm to hot summers and very cold winters. The 

climatic conditions across the northern plains are 

caused by three main types of air masses that can 

affect the region during every season of the year. 

These air masses are a continental polar (dry) air 

mass from the north, a maritime polar (Pacific Ocean) 

Flooding in eastern North Dakota, April 1997. 

(Photograph from Rural Electric Cooperative and Rural 

Telephone Cooperative Magazine, North Dakota.) 

air mass from the northwest, and a tropical air mass 

that is called continental tropical (dry) if it originates 

from the southwest or maritime tropical (moist) if it 

originates from the southeast (Gulf of Mexico). The 

juxtaposition of these air masses over the region determines the amount and location of precipitation occurring at any given time (U.S. Geological Survey, 1991). 

During the summer, precipitation is caused 

by thunderstorms that develop when warm, moist 

air that originates in the Pacific Ocean or Gulf of 

Mexico contacts continental polar air masses moving 

across the region. The thunderstorms form when 

warm, moist, unstable air near the ground surface 

meets colder air aloft. Precipitation in the region can 

be enhanced when the moisture-laden air masses 

moving across the continent are modified to include 

moisture recycled through the land-vegetation-air 

interface. 

During the winter, snowfall occurs when continental polar air masses that usually have low temperatures and little moisture move south from Canada 

into the northern plains and meet maritime polar or 

tropical air masses that bear moisture. The results are 

mid-latitude frontal systems that usually provide 

GENERAL CLIMATOLOGY 3 
precipitation over large areas for an extended period 

of time. Generally, excessive snowfall occurs when the 

frontal systems moving eastward stall over the region 

and continue to receive moisture from maritime tropical air masses moving northward. 

PRECIPITATION 

Annual precipitation in the northern 

plains in the area of flooded streams averages 

about 13 inches in the west and about 26 inches in 

the east. About 65 to 75 percent of the precipitation falls during the growing season, April through 

September. If successive periods of normal to muchabove-normal precipitation occur, soils become nearly 

saturated, and numerous potholes, sloughs, and small 

lakes in the region fill and retain high water levels. 

Normal to much-above-normal precipitation occurred 

throughout the northern plains from 1993 to the 

fall of 1996 (Michael Gillispie, National Weather 

Service, written commun., 1997; Jim Zandlo, 

Minnesota State Climatologist, written commun., 

1997; Tara Williams-Sether, U.S. Geological Survey, 

written commun., 1998). Thus, when additional 

moisture was added to the water-laden systems in the 

fall and winter of 1996-97, conditions were set for the 

1997 spring floods. 

Monthly precipitation at 10 weather stations in 

the northern plains during September 1996 through 

April1997 and 30-year precipitation normals for 

September through April 1961-90 are given in table 1 

and shown in figure 2. The precipitation patterns at the 

stations-Bismarck, Fargo, and Grand Forks, N.Dak.; 

Fergus Falls, Mankato, and Montevideo, Minn.; 

and Aberdeen, Brookings, Huron, and Sioux Falls, 

S. Dak.-are representative of those throughout the 

flood-affected region. 

Fall Precipitation (September through 

October 1996) 

During September through October 1996, 

precipitation in the flood-affected region generally 

was between 4 and 8 inches; however, precipitation 

in east-central South Dakota was more than 10 inches 

(fig. 3). Most of the region received between 100 and 

300 percent of the 30-year precipitation normals for 

September through October 1961-90 (fig. 4), and 

single-day totals at many of the weather stations 

nearly equaled or exceeded the monthly normals 

for 1961-90. 

During September 1996, monthly precipitation 

ranged from 87 to 286 percent of normal, and precipitation at 6 of the 10 weather stations was above normal 

(table 1). Many stations had single-day precipitation 

totals that were more than one-half of the monthly 

normal for 1961-90 at those stations. The single-day 

total at Mankato, Minn., was more than 1.5 times the 

monthly normal. 

Single-day Percent of 

Station Date precipitation monthly total 

(inches) normal 

Bismarck, N.Dak. 09/19/96 1.21 81 

Fargo, N.Dak. 09/01/96 1.07 53 

Fergus Falls, Minn. 09/07/96 1.62 67 

Mankato, Minn. 09/03/96 5.44 177 

Aberdeen, S. Dak. 09119/96 1.41 76 

Huron, S. Dak. 09119/96 1.28 74 

During October 1996, monthly precipitation 

ranged from 92 to 317 percent of normal, and precipitation at 7 of the 10 weather stations was above normal 

(table 1). Many stations had single-day precipitation 

totals that were more than one-half of the monthly 

normal for 1961-90 at those stations. 

Single-day Percent of 

Station Date precipitation monthly total 

(inches) normal 

Bismarck, N.Dak. 10/26/96 1.01 112 

Fargo, N. Dak. 1 10/30/96 1.00 

Fergus Falls, Minn. 10/30/96 1.00 57 

Montevideo, Minn. 10117/96 1.70 90 

Aberdeen, S.Dak. 10/26/96 1.37 122 

10/29/96 1.71 153 

Brookings, S.Dak. 10117/96 1.56 94 

Huron, S. Dak. 10/29/96 1.28 87 

1 Fargo probably received more than 1.00 inch of precipitation on 

October 30, 1996, but, because of missing data, the reported value for that 

date is substantially lower than the value for weather stations in the 

surrounding area. Therefore, a corrected daily total for Fargo was derived 

from an average total based on daily totals at all of the weather stations 

within Fargo's climatological division. 

4 Precipitation in the Northern Plains, September 1996 through April 1997 
Table 1. Monthly precipitation at 1 0 weather stations in the northern plains during September 1996 through April 1997 and 30-year precipitation normals for September 

through April 1961-90 

[Data from Owenby and Ezell, 1992a, 199:2b, 1992c, and U.S. Department of Commerce, National Oceanic and Atmospheric Administration, National Environmental Satellite, Data and Information Service, 

1996-97a, 1996-97b, 1996-97c; bold values indicate normal precipitation was exceeded] 

Bismarck, Fargo, Grand Forks, Fergus Falls, Mankato, Montevideo, Aberdeen, Brookings, Huron, Sioux Falls, 

North North North South South South South 

Dakota Dakota Dakota Minnesota Minnesota Minnesota Dakota Dakota Dakota Dakota 

September 

Monthly precipitation (inches) 2.80 3.18 1.94 3.07 6.93 2.47 5.32 2.61 3.69 2.82 

Normal (inches) 1.49 1.99 2.24 2.42 3.07 2.68 1.86 2.64 1.72 3.02 

Percent of normal 188 160 87 127 226 92 286 99 215 93 

October 

Monthly precipitation (inches) 1.73 11.86 1.26 2.97 2.24 3.32 3.55 2.75 3.36 1.63 

Normal (inches) .90 1.68 1.29 1.74 2.28 1.89 1.12 1.66 1.47 1.78 

Percent of normal 192 111 98 171 98 176 317 166 229 92 

November 

Monthly precipitation (inches) 1.84 1

1.53 1.80 12.20 4.24 2.27 1.40 1.41 .25 2.91 

Normal (inches) .49 .73 .65 .89 1.55 1.34 .59 .81 .72 1.09 

Percent of normal 376 210 277 247 274 169 237 174 35 267 

December 

Monthly precipitation (inches) .68 .69 1.32 .99 1.50 .66 .87 .29 .26 .78 

Normal (inches) .51 .65 .64 .66 1.15 .88 .41 .33 .47 .70 

Percent of normal 133 106 206 150 130 75 212 88 55 111 

January 

Monthly precipitation (inches) .84 .53 .60 1

2.21 1.59 1.41 1.34 .90 .93 .41 

Normal (inches) .45 .67 .72 .73 .90 .98 .37 .32 .41 .51 

""C Percent of normal 187 79 83 302 177 144 362 281 227 80 

:II 

m 

0 February ;; 

:::::i Monthly precipitqtion (inches) 59 .59 .30 .RO .24 .20 .RR .56 .50 1.39 l> 

-t Normal (inches) .43 .45 .49 .54 .79 1.16 .47 .42 .68 .64 5 

z Percent of normal 137 131 61 148 30 17 187 133 74 217 

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Table 1. Monthly precipitation at 1 0 weather stations in the northern plains during September 1996 through April 1997 and 30-year precipitation normals for September 

through April 1961-90-Continued 

[Data from Owenby and Ezell, 1992a, 1992b, 1992c. and U.S. Department of Commerce, National Oceanic and Atmospheric Administration. National Environmental Satellite. Data and Information Service, 

1996-97a, 1996-97b, 1996-97c; bold values indicate normal precipitation was exceeded] 

Bismarck, Fargo, Grand Forks, Fergus Falls, Mankato, Montevideo, Aberdeen, Brookings, Huron, Sioux Falls, 

North North North South South South South 

Dakota Dakota Dakota Minnesota Minnesota Minnesota Dakota Dakota Dakota Dakota 

March 

Monthly precipitation (inches) .97 1.89 2.87 1

1.42 .97 1.21 .79 .67 .16 .13 

Normal (inches) .77 1.06 .94 1.13 1.95 1.64 1.34 1.24 1.66 1.64 

Percent of normal 126 178 93 126 50 74 59 54 10 14 

November through March 

Monthly precipitation (inches) 4.92 5.23 4.89 7.62 8.54 5.75 5.28 3.83 2.11 5.72 

Normal (inches) 1.65 3.56 3.44 3.95 6.34 6.00 3.18 3.12 3.94 4.58 

Percent of normal 185 147 142 193 135 96 166 123 53 125 

April 

Monthly precipitation (inches) 3.26 2.14 1.64 2.90 1.58 2.52 2.01 2.14 2.70 2.43 

Normal (inches) 1.67 1.82 1.35 2.12 2.79 2.39 1.95 2.07 1.09 2.52 

Percent of normal 195 118 121 137 57 105 103 103 129 96 

September through April 

Monthly precipitation (inches) 12.71 12.41 9.73 16.56 19.29 14.06 16.16 11.33 11.85 12.60 

Normal (inches) 6.71 9.05 8.32 10.23 14.48 12.96 8.11 9.49 9.22 11.90 

Percent of normal 189 137 117 162 133 108 199 119 129 106 

1 Average for all stations within climatological division (excluding those stations with missing data). 2Value from University of North Dakota weather station. 
ffl 6 I 

(.) 

~ 5 

z- 4 

0 

i= 3 ;:: 

§; 2 (.) 

LlJ g:1 

BISMARCK, NORTH DAKOTA 

u. LL--W- ~--u_ ~ 

7,.---,--,--,--,--,---,--, 

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FARGO, NORTH DAKOTA 

u. LL--u_ ~--u_ ~ 

7ro---.--,--,--,--,---,--, 

ffl 6 I 

(.) 

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GRAND FORKS, NORTH DAKOTA 

Sept 

FERGUS FALLS, MINNESOTA 

MANKATO, MINNESOTA 

MONTEVIDEO, MINNESOTA 

ABERDEEN, SOUTH DAKOTA 

BROOKINGS, SOUTH DAKOTA 

HURON, SOUTH DAKOTA 

ffJ 6 I 

~ 5 SIOUX FALLS, SOUTH DAKOTA 

z" 4 

0 

i= 3 ;:: 

§; 2 (.) 

LlJ g:1 

EXPLANATION 

• Monthly precipitation 

D 30-year precipitation normal 

D Area of flooding streams 

~ Weather station 

Figure 2. Monthly precipitation at 1 0 weather stations in the northern plains during September 1996 through 

April 1997 and 30-year precipitation normals for September through April 1961-90. (Data from Owenby and Ezell, 

1992a, 1992b, 1992c, and U.S. Department of Commerce, National Oceanic and Atmospheric Administration, 

National Environmental Satellite, Data and Information Service, 1996-97a, 1996-97b, 1996-97c.) 

PRECIPITATION 7 
Base from U.S. Geological Survey 

1 :2,000,000, 1972 

gs• 

0 40 80 120 MILES 

EXPLANATION 

-4- Line of equal precipitation- Hachures indicate 

equal or less precipitation. Interval variable 

48° 

Figure 3. Areal distribution of precipitation, in inches, for the northern plains, September through October 1996. (Data 

from U.S. Department of Commerce, National Oceanic and Atmospheric Administration, National Environmental Satellite, 

Data and Information Service, 1996-97a, 1996-97b, 1996-97c.) 

The five greatest September through October 

precipitation totals for six weather stations-Bismarck 

and Grand Forks, N. Oak.; Lake Itasca and Morris, 

Minn.; and Aberdeen and Brookings, S. Dak.-are 

given in table 2 along with the September through 

October 1996 precipitation total at each station and the 

mean for the period of record. The Lake Itasca and 

Morris weather stations (fig. 1) were substituted for 

the Fergus Falls, Mankato, and Montevideo weather 

stations, which had limited or missing data in their 

long-term records (Mathew Werner, High Plains 

Climate Center, written commun. , 1998). September 

through October 1996 was the 12th wettest period in 

122 years of record at Bismarck, the 33d wettest 

period in 65 years of record at Grand Forks, the 6th 

wettest period in 85 years of record at Lake Itasca, the 

4th wettest period in 111 years of record at Morris, the 

wettest period in 65 years of record at Aberdeen, and 

the 19th wettest period in 103 years of record at 

Brookings. The precipitation total at Aberdeen was 

about 35 percent greater than the second greatest total 

of 6.55 inches in 1946. The precipitation totals at all of 

the weather stations except Grand Forks were at least 

44 percent greater than the mean for the period of 

record at each station. 

The above-normal precipitation that occurred 

in the northern plains in the fall of 1996 resulted in 

above-normal soil-moisture levels in most of the 

region before freezeup. These soil-moisture conditions 

added to the potential for severe flooding because, if 

the ground is near saturation at freezeup, an impermeable soil layer is formed during freezeup. This impermeable soil layer can retard or prevent any additional 

moisture from infiltrating the ground. 

Soil-moisture data for the northern plains for the 

fall of 1996 were limited. However, a drought severity 

index (long-term Palmer) by climatological division 

for September 28, 1996, indicated near-normal soilmoisture conditions in central and eastern North 

Dakota, incipient drought conditions in southeastern 

8 Precipitation in the Northern Plains, September 1996 through April1997 
Minnesota, and extremely moist conditions in central 

and eastern South Dakota (U.S. Department of 

Commerce, National Oceanic and Atmospheric 

Administration/United States Department of 

Agriculture Weather Facility, 1996). In North Dakota, 

soil-moisture levels for the fall of 1996 ranged from 

4.0 inches in the west to 10.0 inches in the southeast 

(Charlene Prindiville, National Weather Service, 

written commun., 1998). [Soil-moisture level is the 

amount of moisture (water) in the soil zone.] In 

Minnesota, soil-moisture levels at the Morris WestCentral Experimental Station increased from about 

5.5 inches on October 1, 1996, to more than 7.5 inches 

on November 1, 1996 (Mark Seeley, University of 

Minnesota, Department of Soil, Water, and Climate, 

written commun., 1997). Much of this increase 

resulted from the 1.98 inches of precipitation that 

occurred at Morris on October 30, 1996. The 7.5-inch 

soil-moisture level compared closely with an 8.0-inch 

Base from U.S. Geological Survey 

1 :2,000,000, 1972 

soil-moisture level for west-central Minnesota in 

March 1997, suggesting that soil-moisture conditions 

were enhanced by the additional precipitation in the 

fall of 1996 before freezeup and did not change appreciably through the winter. 

Winter Precipitation (November 1996 

through March 1997) 

During November 1996 through March 1997, 

precipitation at all 10 weather stations was between 

3.83 and 8.54 inches. Much of the region received 

about 125 to 200 percent of the 30-year precipitation 

normals for November 1996 through March 1997. The 

above-normal precipitation resulted in record or nearrecord snowfalls in much of central and eastern North 

Dakota, western Minnesota, and central and eastern 

South Dakota. The largest snowfall totals exceeded 

40 80 120 MILES 

EXPLANATION 

-100- Line of equal precipitation, in percent of 30-year 

precipitation normal- Interval I 00 percent 

Figure 4. Areal distribution of precipitation, in percent of 30-year precipitation normal, for the northern plains, 

September through October 1961-90. (Data from Owenby and Ezell, 1992a, 1992b, 1992c, and U.S. Department of 

Commerce, National Oceanic and Atmospheric Administration, National Environmental Satellite, Data and Information 

Service, 1996-97a, 1996-97b, 1996-97c.) 

PRECIPITATION 9 
Table 2. The five greatest September through October precipitation totals, September through October 1996 precipitation 

totals, and means for the period of record at six weather stations in the northern plains 

[Data from Sandra Wiehe (National Weather Service, written commun., 1998) and Mathew Werner (High Plains Climate Center, written commun., 1998); 

record length given in parentheses; precipitation total given in inches; I 996 precipitation total given in bold; 1996 rank given in brackets] 

Bismarck, Grand Forks, Lake Itasca, Morris, Aberdeen, Brookings, 

North Dakota North Dakota Minnesota Minnesota South Dakota South Dakota 

(122 years) (65 years) (85 years) (111 years) (65 years) (103 years) 

Year Total Year Total Year Total Year Total Year Total Year Total 

Five greatest September through October precipitation totals 

1994 8.42 1957 9.48 1984 11.46 1984 11.03 1996 8.87 1946 10.23 

1977 7.93 1973 7.46 1971 11.34 1971 9.16 1946 6.55 1900 8.30 

1876 5.91 1981 6.94 1973 9.47 1982 8.32 1941 6.18 1984 8.26 

1900 5.70 1950 6.61 1970 8.21 1996 7.85 1982 6.09 1911 8.15 

1971 5.37 1961 6.56 1946 8.04 1921 7.76 1977 5.60 1906 8.14 

September through October 1996 precipitation total 

1996 4.53 1996 2.99 1996 7.89 1996 7.85 1996 8.87 1996 5.36 

[Rank 12] [Rank 33] [Rank 6] [Rank 4] [Rank 1] [Rank 19] 

Mean for period of record 

Mean 2.86 Mean 3.33 Mean 4.49 

100 inches and occurred in the southern part of the 

Red River of the North Basin, the middle part of the 

Big Sioux River Basin, and near the Missouri River in 

southern North Dakota (fig. 5). 

Snowfall often is difficult to measure because 

of the variability in weather conditions, and periods 

of missing data often occur. Therefore, total precipitation is the focus of this discussion, but snowfall is 

discussed when continuous data records exist. Cumulative snowfall at six selected weather stations during 

November 1996 through April1997 is shown in 

figure 6. The influences of some of the snowstorms 

occurring in the region are evident by the vertical 

rises on the graphs. The presence of a major snowstorm over the region is indicated when the rises, such 

as those in mid-December and early April, on the individual graphs coincide. 

During November 1996, monthly precipitation at 9 of the 10 weather stations ranged from 

169 to 376 percent of normal (table 1). Precipitation at six of the nine stations ranged from 210 to 

277 percent of normal, and precipitation at one station 

(Bismarck) was 376 percent of normal. Monthly 

precipitation ranged from 0.25 inch at Huron to 

4.24 inches at Mankato. In terms of snowfall 

(fig. 6), Bismarck received 25.2 inches, Grand Forks 

received 14.4 inches, Mankato received 11.5 inches, 

Montevideo received 15.0 inches, Aberdeen received 

20.3 inches, and Sioux Falls received 11.3 inches. 

Mean 4.01 Mean 2.92 Mean 3.72 

During December 1996, monthly precipitation 

at 7 of the 10 weather stations ranged from 106 to 

212 percent of normal (table 1). Monthly precipitation 

ranged from 0.26 inch at Huron to 1.50 inches at 

Mankato. In terms of snowfall (fig. 6), Bismarck 

received 13.5 inches, Grand Forks received 30.2 inches, 

Mankato received 15.5 inches, Montevideo received 

20.6 inches, Aberdeen received 13.9 inches, and Sioux 

Falls received 19.8 inches. The snowfall at Sioux 

Falls was the 4th highest on record for that month 

and the 20th highest on record for all months (Richard 

Ryrholm, National Weather Service, written commun., 

1998). 

During January 1997, monthly precipitation 

at 7 of the 10 weather stations ranged from 144 

to 362 percent of normal (table 1). Monthly precipitation ranged from 0.41 inch at Sioux Falls to an 

estimated 2.21 inches at Fergus Falls. In terms 

of snowfall (fig. 6), Bismarck received 15.1 inches, 

Grand Forks received 19.9 inches, Mankato received 

11.1 inches, Montevideo received 16.5 inches, 

Aberdeen received 19.2 inches, and Sioux Falls 

received 8.8 inches. 

During February 1997, monthly precipitation 

at 6 of the 10 weather stations ranged from 131 to 

217 percent of normal (table 1). Monthly precipitation 

ranged from 0.20 inch at Montevideo to 1.39 inches 

at Sioux Falls. In terms of snowfall (fig. 6), Bismarck 

received 9.2 inches, Grand Forks received 7.6 inches, 

10 Precipitation in the Northern Plains, September 1996 through April 1997 
Mankato received 5.6 inches, Montevideo received 

5.0 inches, Aberdeen received 9.2 inches, and Sioux 

Falls received 16.5 inches. 

During March 1997, precipitation generally was 

less than normal. Monthly precipitation was above 

normal at only 3 of the 10 weather stations and ranged 

from 126 to 178 percent of normal (table 1). The 

remaining seven stations received between 10 and 

93 percent of the normal amount of precipitation at 

those stations. Monthly precipitation ranged from 

0.16 inch at Huron to 1.89 inches at Fargo. In terms 

of snowfall (fig. 6), Bismarck received 16.1 inches, 

Grand Forks received 17.5 inches, Mankato received 

9.5 inches, Montevideo received 12.5 inches, 

Aberdeen received 8.5 inches, and Sioux Falls 

received 1.3 inches. 

Base from U.S. Geological Survey 

1 :2,000,000, 1972 

Spring Precipitation (April 1997) 

During April 1997, precipitation was again 

greater than normal. Monthly precipitation at 8 

of the 10 weather stations ranged from 103 to 

195 percent of normal (table 1). Monthly precipitation ranged from 1.58 inches at Mankato to 

3.26 inches at Bismarck. The precipitation occurring in April was not always in the form of snow. 

However, in the first part of April, Bismarck 

received 17.5 inches of snowfall, Grand Forks 

received 8.0 inches, Mankato received 4.0 inches, 

Montevideo received 4.3 inches, Aberdeen received 

4.6 inches, and Sioux Falls received 6.0 inches. 

Most of the snowfall occurred during a blizzard 

on April 5-6, 1997. 

95° 

40 80 120 MILES 

EXPLANATION 

-100- Line of equal snowfall- Dashes indicate snowfall of at 

least II 0 inches but less than 120 inches. Hachures 

indicate equal or less snowfall. Interval variable 

Figure 5. Areal distribution of snowfall, in inches, for the northern plains, November 1996 through April1997. (Data from 

U.S. Department of Commerce, National Oceanic and Atmospheric Administration, National Environmental Satellite, Data 

and Information Service, 1996-97a, 1996-97b, 1996-97c.) 

48° 

PRECIPITATION 11 
100 

_j BISMARCK, NORTH DAKOTA GRAND FORKS, NORTH DAKOTA --' 80 <( 

lL 

:s: 

OC!J 

Zl!J 60 C!JI 

wU 

>~ 

i=z <(- 40 

--' 

::::> 

::::; 

::::> 20 u 

100 

_j 

--' MANKATO, MINNESOTA MONTEVIDEO, MINNESOTA 80 <( 

lL 

:s: 

OC!J 

ZW 60 C!JI 

wU 

>~ 

i=z <(- 40 

--' 

::::> 

::::; 

::::> 20 u 

0 

100 

_j 

--' ABERDEEN, SOUTH DAKOTA SIOUX FALLS, SOUTH DAKOTA 80 <( 

lL 

:s: 

OCil 

Zl!J 60 C!JI 

wU 

>~ 

i=z <(- 40 

--' 

::::> 

::::; 

::::> 20 u 

0 M A 

1996 1997 1996 1997 

EXPLANATION 

D Area of flooding streams 

~ Weather station 

Figure 6. Cumulative snowfall at six weather stations in the northern plains, November 1996 through April1997. 

(Data from U.S. Department of Commerce, National Oceanic and Atmospheric Administration, National Environmental Satellite, Data and Information Service, 1996-97a, 1996-97b, 1996-97c.) 

12 Precipitation in the Northern Plains, September 1996 through April1997 
The precipitation in April aggravated already 

serious flooding by adding to the streamflows. The 

storm that occurred on April 5-6, 1997, was preceded 

in many places by wind-driven rain and sleet. The 

weather conditions hampered flood and rescue operations by closing many roads. Windspeeds were as 

much as 70 miles per hour in many places, and wind 

and ice toppled trees and powerlines in many areas 

of the region. In central and eastern North Dakota, 

5,729 power poles were lost to ice damage, causing 

about 36,150 consumers to be without power for many 

days (North Dakota Association of Rural Electric 

Cooperatives, 1997). The loss of power inhibited the 

ability of the U.S. Geological Survey to collect and 

transmit data from several streamflow-gaging stations 

in the region. 

Livestock losses across the region also were 

high. In North Dakota, unofficial reports indicate 

90,000 to 120,000 head of cattle, including many 

calves, were lost as a result of the blizzard. In South 

Dakota, total livestock losses for the winter, including 

during the blizzard, were estimated to be more than 

296,000 (Teller and Burr, 1998). The floodwaters and 

severe weather forced thousands of people to flee their 

homes and caused more than $2 billion in damages to 

the region. 

With the additional snowfall in April, many 

areas in the northern plains set new records for total 

snowfall. Official and unofficial snowfall totals for 

October 1996 through April 1997 at 9 of the 10 weather 

stations and the record October through April snowfall 

before 1996-97 are listed in the following table. 

Snowfall total for October 1996 

Station through April1997 

(inches) 

Bismarck, N.Dak. 101.3 

Fargo, N. Dak. 117.0 

Grand Forks, N.Dak. 97.9 

Fergus Falls, Minn. 105.3 

Mankato, Minn. 57.2 

Montevideo, Minn. 73.9 

Aberdeen, S.Dak. 75.7 

Brookings, S. Dak 48.3 

Huron, S. Dak. 1 

Sioux Falls, S. Dak. 63.7 

1 Not reported because of missing record. 

Downed power lines and towers in eastern North Dakota 

were the result of a blizzard on April 5-6, 1997. (Photograph 

from North Dakota National Guard and North Dakota Water 

Education Foundation.) 

ANALYSIS OF SELECTED STORMS 

After the wet fall of 1996, precipitation 

continued to accumulate across the northern plains. 

Weather patterns that kept temperatures below normal 

produced several storms during the winter and early 

spring. Many of the storms were quick-moving 

"clipper"-type storms that produced snowfall totals 

of a few inches, but a few of the storms, typically 

maritime tropical types, persisted over the region 

and produced snowfall totals exceeding 12 inches 

in many places. 

Record October through April 

snowfall before 1996-97 

Remarks about 1996-97 

Total Date (inches) 

91.8 1993- 94 New record. 

89.1 1993-94 New record. 

91.0 1896-97 New record. 

84.8 1891-92 New record. 

70.8 1961-62 No new record. 

76.3 1950-51 No new record. 

76.8 1993-94 Second highest on record. 

72.5 1892-93 Sixth highest on record. 

94.7 1947-48 No new record. 

ANALYSIS OF SELECTED STORMS 13 
December 16-18, 1996 

A storm formed in southern Canada on 

December 15, 1996, and spread snow across the 

western part of the region. The storm moved slowly 

across North Dakota, Minnesota, and South Dakota on 

December 16-17, 1996, and into Wisconsin on 

December 18, 1996 (fig. 7). Temperatures in the 

region were below freezing both before and after the 

storm, indicating no snowmelt occurred. Snowfall was 

widespread, and unofficial totals of about 24 inches 

were reported. Official reports indicate Bismarck 

received 4.9 inches of snowfall, Grand Forks received 

9.8 inches, Mankato received 2.3 inches, Montevideo 

received 0.60 inch, Aberdeen received 7.5 inches, and 

Sioux Falls received 11.0 inches. Windspeeds during 

the storm ranged from 20 to 60 miles per hour and 

caused considerable blowing and redistribution of 

snow, particularly in sheltered areas. Temperatures 

plunged to between -20°F (degrees Fahrenheit) and 

-40°F across the region after the storm, and new 

low-temperature records were set in many places. 

Another storm moving through the region a few days 

later produced additional snowfall totals of 4.0 to 

10 inches. 

. ..... 

EXPLANATION 

v.-.:.:_: j Area of precipitation for North Dakota, 

South Dakota, and Minnesota 

___.___ Cold front 

- Warmfront 

Bismarck 

-o Wind-direction arrow and weather station 

L Low atmospheric-pressure area 

H High atmospheric-pressure area 

Figure 7. Average weather patterns over the northern plains, December 16-18, 1996. (Data from U.S. Department of 

Commerce, National Oceanic and Atmospheric Administration, n.d.) 

14 Precipitation in the Northern Plains, September 1996 through April1997 
EXPLANATION 

U Area of precipitation for Nonh Dakota, 

South Dakota, and Minnesota 

___...._ Cold front 

- Warm front 

Bismarck 

-o Wind-direction arrow and weather station 

L Low atmospheric-pressure area 

H High atmospheric-pressure area 

Figure 8. Average weather patterns over the northern plains, January 4-5, 1997. (Data from U.S. Department of Commerce, 

National Oceanic and Atmospheric Administration, n.d.) 

January 4-5, 1997 

The storm that occurred on January 4-5, 1997, 

formed in eastern Colorado and western Kansas on 

January 3, 1997 (fig. 8). Weather conditions in the 

northern plains were relatively warm, and some 

temperatures were in the 40°F range. A wind flow 

from the south at ground surface brought moisture into 

the central part of the region on January 3, 1997, and 

aided in the development of the storm. On January 4, 

1997, the storm moved quickly into southern Iowa, 

spreading rain and snow over the southern part of the 

region, and on January 5, 1997, the storm moved 

slowly into Wisconsin. Temperatures throughout the 

region were around zero, and snowfall totals varied. 

Bismarck received 7.5 inches of snowfall, Grand 

Forks received a trace, Mankato received 2.9 inches, 

Montevideo received 8.0 inches, Aberdeen received 

12.8 inches, and Sioux Falls received 2.2 inches. 

Fergus Falls received 12 inches of snow on 

January 5, 1997, and had a combined 3-day total of 

24 inches, which was 12.6 inches above the monthly 

normal for January (Jim Zandlo, Minnesota State 

Climatologist, written comrnun., 1997). A few days 

later, these cities received additional snowfall totals 

of 1.0 to 8.0 inches. 

ANALYSIS OF SELECTED STORMS 15 
April 5-6, 1997 

Late spring snowstorms are common in 

parts of the northern plains, but the intensity and 

timing of the April 5-6, 1997, snowstorm made it 

one of the worst on record (fig. 9). Besides snow, 

this "Colorado low" storm produced rain, sleet, and 

ice in many areas. The storm was caused by a warm, 

moist flow of air from the Gulf of Mexico entering 

the central and northern plains on April3, 1997. 

Some temperatures in the region reached 50°F to 

60°F before colder air began moving south across 

Montana. The interaction of the existing warm air 

mass with the colder air mass from Montana aided 

in the development of the storm. On April 5, 1997, 

the storm center strengthened and moved from 

Colorado into Nebraska and South Dakota, 

spreading rain, sleet, and snow into the northern 

plains. On April 6, 1997, the storm intensified and 

moved northward into western Minnesota. Several 

inches of rain and sleet preceded the snow in southeastern North Dakota, western Minnesota, and 

eastern South Dakota while snow fell in the rest of 

the region. Precipitation spread across the entire 

region on April 6, 1997. Windspeeds of 30 to 

50 miles per hour were common, and, combined with 

temperatures of zero to 20°F, brought windchills of 

-60°F. Bismarck received 17.5 inches of snowfall, 

Snow from an Apri/5-6, 1997, blizzard covers cars in a 

Bismarck, North Dakota, mall parking lot. (Photograph 

from Bismarck Tribune.) 

Melting ice and snow cause the Red River of the North 

to flood a Clay County, Minnesota, road on April9, 1997. 

(Photograph from U.S. Geological Survey.) 

Grand Forks received 8.0 inches, Mankato 

received 2.5 inches, Montevideo received 

3.0 inches, Aberdeen received 4.2 inches, and 

Sioux Falls received 1.5 inches. Some of these 

cities also received rain and sleet before the snowfall. 

Temperatures, which were 10 degrees above normal 

before the storm, plunged to about 20 degrees below 

normal as the storm moved into Canada. The 

additional moisture from the storm added to the 

increasing streamflows in rivers and streams 

in the region. 

CHRONOLOGICAL OVERVIEW 

Flooding in the northern plains usually is 

caused by spring snowmelt, and the severity of 

the flooding is affected by antecedent climatic 

conditions such as above-normal precipitation 

in the fall, high soil-moisture levels at freezeup, 

above-normal snowfall in the winter, a late 

spring thaw, above-normal precipitation during 

the spring thaw, and ice jams on rivers and 

streams. Many of these conditions were present 

in the northern plains before and during the 1997 

spring floods. 

Many areas in the northern plains received 

normal to much-above-normal precipitation from 

1993 to the fall of 1996. Thus, soils in lowland 

areas became saturated and numerous potholes, 

16 Precipitation in the Northern Plains, September 1996 through April1997 
sloughs, and small lakes in the region were filled 

and retained high water levels before the winter 

of 1996-97. Soil moisture in upland areas was below 

normal to normal before the winter of 1996--97 but 

was above normal after above-normal precipitation 

during September and October 1996. During 

September, 6 of 10 weather stations in the northern 

plains received above-normal precipitation, and 

during October, 7 of 10 stations received abovenormal precipitation. During September, precipitation 

was more than 200 percent of normal at Mankato, 

Minn., and at Aberdeen and Huron, S.Dak.; and, 

during October, precipitation was more than 

200 percent of normal at Aberdeen and Huron. 

At Aberdeen, September through October 1996 

was the wettest in 65 years of record. At many 

of the weather stations, single-day precipitation 

totals during September and October nearly equaled 

or exceeded the monthly normals for 1961-90. On 

September 3, 1996, Mankato received 5.44 inches 

of precipitation, the second largest single-day 

total ever recorded at that station. In October 1996, 

Aberdeen had two single-day totals that exceeded the 

monthly normal of 1.12 inches. 

A series of winter storms moving through 

the northern plains between November 1996 and 

early March 1997 caused above-normal precipitation, mostly in the form of snow. In any one 

EXPLANATION 

1.:_:. ::·; -j Area of precipitation for North Dakota, 

South Dakota, and Minnesota 

__..,__ Cold front 

___..__ Warm front 

Bismarck 

-o Wind-direction arrow and weather station 

L Low atmospheric-pressure area 

H High atmospheric-pressure area 

Figure 9. Average weather patterns over the northern plains, April 5-6, 1997. (Data from U.S. Department of Commerce, 

National Oceanic and Atmospheric Administration, n.d.) 

CHRONOLOGICAL OVERVIEW 17 
month, no less than 3 and as many as 9 of the 

10 weather stations received above-normal 

precipitation. Precipitation was more than 

200 percent of normal at many of the stations. 

This excessive precipitation resulted, in part, 

from record snowfalls at 4 of the 10 weather 

stations in the region. Because temperatures in 

the northern plains were below normal longer 

than usual, fewer mild days (days with temperatures at or above 32°F) occurred during the 

winter. The absence of these mild winter days 

along with frozen moist soils slowed the gradual 

dissipation of accumulated snowfall through 

sublimation, evaporation, or infiltration in much 

of the region. 

During March, snowmelt and warm 

temperatures generally began to occur in the 

southwestern part of the northern plains. By the 

second and third weeks of March, temperatures 

rose to above freezing and peak streamflows 

began occurring on many rivers and streams in 

western North Dakota and central and western 

South Dakota. 

In the northern part of the region, snowpacks 

at the beginning of freeze up covered frozen moist 

soils, minimizing the infiltration of any additional 

fall and winter moisture. For the most part, additional fall and winter moisture was retained by the 

snowpacks. Moisture in the snowpacks, along with 

above-normal precipitation during March, increased 

runoff during snowmelt in many areas in the 

northern part of the region. 

During April1997, temperatures across 

many parts of the northern plains dropped to 

below freezing, and a final winter storm moved 

into the region on April 5-6, 1997. Official and 

unofficial snowfall totals for October 1996 

through April 1997 include 101.3 inches at 

Bismarck, 117 inches at Fargo, 97.9 inches at 

Grand Forks, and 105.3 inches at Fergus Falls. 

At 3 other weather stations, snowfall totals 

ranked in the top 10 highest snowfalls for the 

period of record at that station. Montevideo 

received 73.9 inches of snowfall, Aberdeen 

received 75.7 inches, and Brookings received 

48.3 inches. 

The storm on April 5-6, 1997, caused 

already cold temperatures to drop severely and 

brought high winds and as much as 2 feet of snow 

to many places. The storm was preceded by winddriven rain and sleet in many areas, and wind and 

ice toppled trees and many power lines, leaving 

thousands of people without power for days. The 

snowfall closed schools and businesses and blocked 

many roads throughout the region, hampering flood 

and rescue operations. The intensity and timing of 

the storm caused high livestock losses because 

many farmers and ranchers were unable to react in 

time to save their animals. The additional moisture 

from the storm added to increasing streamflows in 

rivers and streams in the region. Ice jams that began 

to form on many of the rivers and streams affected 

the high streamflows. As the floodwaters rushed to 

record highs, towns such as Ada, Minn., and cities 

such as Grand Forks, N.Dak., and East Grand 

Forks, Minn., were evacuated. The floodwaters 

and severe weather forced thousands of people to 

flee their homes, some permanently, and caused 

more than $2 billion in damages to the region. For 

the people of the northern plains, the winter of 

1996-97, combined with the 1997 spring floods, 

was one of the worst natural disasters in recent 

history. 

Bridge structure denotes channel location of the flooding 

Red River of the North. View is looking west to Grand Forks, 

North Dakota, April1997. (Photograph from North Dakota 

Water Education Foundation and North Dakota National 

Guard.) 

18 Precipitation in the Northern Plains, September 1996 through April1997 
REFERENCES 

North Dakota Association of Rural Electric Cooperatives, 

1997, The fury: North Dakota REC/RTC, v. 43, no. 11, 

p. 4-10. 

Owenby, J.R., and EzelL D.S., 1992a, Monthly station 

normals of temperature, precipitation, and heating 

and cooling degree days, 1961-90, Minnesota: U.S. 

Department of Commerce, National Oceanic and 

Atmospheric Administration, National Climatic Data 

Center, Asheville, North Carolina, Climatography of 

the United States No. 81, unpaginated. 

Owenby, J.R., and Ezell, D.S., 1992b, Monthly station 

normals of temperature, precipitation, and heating and 

cooling degree days, 1961-90, North Dakota: U.S. 

Department of Commerce, National Oceanic and 

Atmospheric Administration, National Climatic Data 

Center, Asheville, North Carolina, Climatography of 

the United States No. 81, unpaginated. 

Owenby, J.R., and Ezell, D.S., 1992c, Monthly station 

normals of temperature, precipitation, and heating and 

cooling degree days, 1961-90, South Dakota: U.S. 

Department of Commerce, National Oceanic and 

Atmospheric Administration, National Climatic Data 

Center, Asheville, North Carolina, Climatography of 

the United States No. 81, unpaginated. 

Teller, R.W., and Burr, M.J., 1998, Floods in north-central 

and eastern South Dakota, spring 1997: U.S. Geological Survey Fact Sheet FS-021-98, 4 p. 

U.S. Department of Commerce, National Oceanic and 

Atmospheric Administration, [n.d.], Daily weather 

maps, Weekly series, December 16-22, 1906; 

December 30, 1996-January 5, 1997; and 

March 31-April 6, 1997: unpaginated. 

U.S. Depattment of Commerce, National Oceanic and 

Atmospheric Administration, National Environmental 

Satellite, Data and Information Service, 1996-97a, 

Climatological data, Minnesota, September 1996 

through April1997: Asheville, North Carolina, v. 102, 

no. 9, through v. 103, no. 4, unpaginated. 

---1996-97b, Climatological data, North Dakota, 

September 1996 through April1997: Asheville, 

North Carolina, v. 105, no. 9, through v. 10<';, no. 4, 

unpaginated. 

---1996-97c, Climatological data, South Dakota, 

September 1996 through April 1997: Asheville, 

North Carolina, v. 101, no. 9, through v. 102, no. 4, 

unpaginated. 

U.S. Department of Commerce, National Oceanic and 

Atmospheric Administration/United States Department of Agriculture Weather Facility, 1996, Weekly 

weather and crop bulletin: October 1, 1996, p. 3. 

U.S. Geological Survey, 1991, National water summary 

1988-89-Hydrologic events and floods an1 droughts: 

U.S. Geological Survey Water-Supply Paper 2400, 

591 p. 

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• Spokane, Washington-Rm. 135, U.S. Post Office 

Building, 904 West Riverside Ave. 

• Washington, D.C.-Rm. 2650, Main Interior Bldg., 

18th and C Sts., NW. 

Maps only may be purchased over the counter at the following 

USGS office: 

• Rolla, Missouri-1400 Independence Rd. 

Electronically 

Some USGS publications, including the catalog ''New Publications of the U.S. Geological Survey," are also available electronically on the USGS's World Wide Web home page at 

http://www.usgs.gov 

Preliminary Determination of Epicenters 

Subscriptions to the periodical "Preliminary Determination of 

Epicenters" can be obtained only from the Superintendent of 

Documents. Check or money order must be payable to the 

Superintendent of Documents. Order by mail fromSuperintendent of Documents 

Government Printing Office 

Washington, DC 20402 

Information Periodicals 

Many Information Periodicals products are available through 

the systems or formats listed below: 

Printed Products 

Printed copies of the Minerals Yearbook and the Mireral Commodity Summaries can be ordered from the Superintendent of 

Documents, Government Printing Office (address ab·we). 

Printed copies of Metal Industry Indicators and Mint"ral Industry Surveys can be ordered from the Center for Disease Control 

and Prevention, National Institute for Occupational ~llfety and 

Health, Pittsburgh Research Center, P.O. Box 18070, Pittsburgh, PA 15236-0070. 

Mines FaxBack: Return fax service 

1. Use the touch-tone handset attached to your fax machine's 

telephone jack. (ISDN [digital] telephones cannot be used with 

fax machines.) 

2. Dial (703) 648-4999. 

3. Listen to the menu options and punch in the numl:er of your 

selection, using the touch-tone telephone. 

4. After completing your selection, press the start button on 

your fax machine. 

CD-ROM 

A disc containing chapters of the Minerals Yearbook ( 1993-

95), the Mineral Commodity Summaries (1995-97), a statistical compendium ( 1970-90), and other publications i" updated 

three times a year and sold by the Superintendent of Documents, Government Printing Office (address above). 

World Wide Web 

Minerals information is available electronically at 

http://minerals.er.usgs.gov/minerals/ 

Subscription to the catalog "New Publications of the U.S. 

Geological Survey" 

Those wishing to be placed on a free subscription list for the 

catalog "New Publications of the U.S. Geological Survey" 

should write toU.S. Geological Survey 

903 National Center 

Reston, VA 20192 

Selected Series of U.S. Geological Survey Publications 

Books and Other Publications 

Professional Papers report scientific data and interpretations 

of lasting scientific interest that cover all facets of USGS investigations and research. 

Bulletins contain significant data and interpretations that are of 

lasting scientific interest but are generally more limited in 

scope or geographic coverage than Professional Papers. 

Water-Supply Papers are comprehensive reports that present 

significant interpretive results of hydrologic investigations of 

wide interest to professional geologists, hydrologists, and engineers. The series covers investigations in all phases of hydrology, including hydrogeology, availability of water, quality of 

water, and use of water. 

Circulars are reports of programmatic or scientific information 

of an ephemeral nature; many present important scientific 

information of wide popular interest. Circulars are distributed 

at no cost to the public. 

Fact Sheets communicate a wide variety of timely information 

on USGS programs, projects, and research. They commonly 

address issues of public interest. Fact Sheets generally are two 

or four pages long and are distributed at no cost to the public. 

Reports in the Digital Data Series (DDS) distribute large 

amounts of data through digital media, including compact discread-only memory (CD-ROM). They are high-quality, interpretive publications designed as self-contained packages for viewing and interpreting data and typically contain data sets, 

software to view the data, and explanatory text. 

Water-Resources Investigations Reports are papers of an 

interpretive nature made available to the public outside the formal USGS publications series. Copies are produced on request 

(unlike formal USGS publications) and are also available for 

public inspection at depositories indicated in USGS catalogs. 

Open-File Reports can consist of basic data, preliminary 

reports, and a wide range of scientific documents on USGS 

investigations. Open-File Reports are designed for fast release 

and are available for public consultation at depositories. 

Maps 

Geologic Quadrangle Maps (GQ's) are multicolor geologic 

maps on topographic bases in 7.5- or 15-minute quadrangle 

formats (scales mainly 1:24,000 or 1:62,500) showing bedrock, 

surficiaL or engineering geology. Maps generally include brief 

texts; some maps include structure and columnar sections only. 

Geophysical Investigations Maps (GP's) are on topographic 

or planimetric bases at various scales. They show results of 

geophysical investigations using gravity, magnetic, seismic, or 

radioactivity surveys, which provide data on subsurface structures that are of economic or geologic significance. 

Miscellaneous Investigations Series Maps or Geologic 

Investigations Series (l's) are on planimetric or to'Jographic 

bases at various scales: they present a wide variety of format 

and subject matter. The series also incudes 7 .5-min' 1te quadrangle photogeologic maps on planimetric bases and rianetary 

maps. 

Information Periodicals 

Metal Industry Indicators (Mil's) is a free monthly newsletter that analyzes and forecasts the economic health of five 

metal industries with composite leading and coincident 

indexes: primary metals, steeL copper, primary and secondary 

aluminum, and aluminum mill products. 

Mineral Industry Surveys (MIS's) are free periocic statistical 

and economic reports designed to provide timely s<-atistical 

data on production, distribution, stocks, and consu11ption of 

significant mineral commodities. The surveys are issued 

monthly, quarterly, annually, or at other regular int~rvals, 

depending on the need for current data. The MIS's are published by commodity as well as by State. A series of international MIS's is also available. 

Published on an annual basis, Mineral Commodity Summaries is the earliest Government publication to furnish estimates 

covering nonfuelmineral industry data. Data sheets contain 

information on the domestic industry structure, Gcvernment 

programs, tariffs, and 5-year salient statistics for more than 90 

individual minerals and materials. 

The Minerals Yearbook discusses the performance of the 

worldwide minerals and materials industry during a calendar 

year, and it provides background information to a~sist in interpreting that performance. The Minerals Yearbook consists of 

three volumes. Volume I, Metals and Minerals, co:'ltains chapters about virtually all metallic and industrial mineral commodities important to the U.S. economy. Volume II, Area Reports: 

Domestic, contains a chapter on the minerals indmtry of each 

of the 50 States and Puerto Rico and the Administered Islands. 

Volume III, Area Reports: InternationaL is published as four 

separate reports. These reports collectively contain the latest 

available mineral data on more than 190 foreign countries and 

discuss the importance of minerals to the economies of these 

nations and the United States. 

Permanent Catalogs 

"Publications of the U.S. Geological Survey, 1879-1961" 

and ~'Publications of the U.S. Geological Survey, 1962-

1970'' are available in paperback book forn1 and as a set of 

microfiche. 

"Publications of the U.S. Geological Survey, 1971-1981" is 

available in paperback book form (two volumes, rnblications 

listing and index) and as a set of microfiche. 

Annual supplements for 1982, 1983, 1984, 1985, 1986, and 

subsequent years are available in paperback book form. 
ISBN 0-607-96338-7 

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