# State of Arizona Exceptional Event Documentation

for the Event of June 16, 2012, for the

Phoenix PM 10 

# Nonattainment Area

Produced by:

Sierra Research, Inc.

Arizona Department of Environmental Quality

Maricopa County Air Quality Department

Maricopa Association of Governments

Final Report

February 13, 2013

## EXECUTIVE SUMMARY

In 2005, Congress identified a need to account for even ts that result in exceedances of the National

Ambient Air Quality Standards (NAAQS ) that are exceptional in nature 1 

### (e.g., not expected to reoccur or

caused by acts of nature beyond man-made controls). In response, EPA promulgated the Exceptional

Events Rule (EER) to address exceptional events in 40 CFR Pa rts 50 and 51 on March 22, 2007 (72 FR

13560). On May 2, 2011, in an attempt to clarify this rule, EPA released draft guidance documents on the

implementation of the EER to State, tribal and lo cal air agencies for review. Based on numerous

comments EPA received on the May 2011 draft, EPA issu ed a revised draft guidance document in June

2012. The EER allows for states and tribes to “flag” air quality monitoring data as an exceptional event

and exclude those data from use in determinations with respect to exceedances or violations of the

NAAQS, if EPA concurs with the demonstr ation submitted by the flagging agency.

Due to the arid nature of the state, Arizona is high ly susceptible to windblown dust events. These events

are often captured by various air quality monitoring equipment throughout the state, sometimes resulting

in exceedances or violations of the PM10 NAAQS. In the past, the Arizona Department of

Environmental Quality (ADEQ) has submitted exceptiona l event documentation for these events. Due in

part to issues within the EER, obt aining concurrence on these events has been a difficult task. The ADEQ

is now taking a new approach and focusing excepti onal event documentation on ev ents that are believed

to be clear-cut exceptional events that are not controllable by huma n intervention, such as the dust events

that frequently occurred during the monsoon seas on of 2011. This new approach was used for the

exceptional event demonstration submitted in Ma rch 2012 by ADEQ for several PM10 events that

occurred from July 2 – July 8, 2011, in the Phoeni x region. In September 2012, EPA concurred that the

July 2–8, 2011 events were indeed exceptional. As a result, this document is designed to follow the

format used in the July 2–8, 2011 events submission.

This demonstration contains detailed informati on about the windblown dust event that affected the

Phoenix PM10 nonattainment area on June 16, 2012. On that day, seven exceedances of the PM10

NAAQS occurred within the nonattainment area. Add itional exceedances occurred outside of the Phoenix

PM10 nonattainment area on this date, and additional documentation may be submitted as a separate

package at a later time. ADEQ contends that the exceedances that were measured on June 16, 2012,

within the Phoenix PM10 nonattainment area were the result of natural events that were not reasonably

controllable or preventable. This assessment repor t of the June 16, 2012, dust ev ent was a co llaborative

effort involving staff from Sierra Research, Inc., the Arizona Depa rtment of Environmental Quality,

Maricopa Association of Governments, Maricopa County Air Quality Department, and Pinal County Air

Quality Control District.

Section I of this assessmen t provides a summary of the exceptional event rules and requirements and lays

out how those rules are met with in this specific assessment.

Section II of this assessme nt introduces the conceptual model of the thunderstorms a nd the subsequent

dust storm that transpired on June 16, 2012, providing a background narrative of the exceptional event.

Section III of this assessment provides data summaries a nd time series graphs that help illustrate that the

event of June 16, 2012, produced PM10 concentrations in excess of normal hist orical fluctuations.

1 Section 319 of the Clear Air Act (CAA), as amended by section 6013 of the Safe Accountable Flexible EfficientTransportation Equity Act: A Legacy for Users (SAFE-TEA-LU of 2005), required EPA to propose the Federal Exceptional

Events Rule (EER) no later than March 1, 2006.

### Section IV of this assessment details the existing area control measures and demonstrates that despite the

presence and enforcement of these controls, the event on June 16, 2012, was not reasonably controllable

or preventable.

Section V of this assessment esta blishes a clear causal connection betw een the natural events of June 16,

2012, and the exceedances of the 24-hour PM10 standard at the monitoring stations. The evidence in this

section (and the previous section on hi storical fluctuations) also confir ms that the event in question both

affected air quality and was the result of natural events.

Section VI of this assessment builds upon the demons tration showing a clear causal connection between

the natural events and the exceedances and conclude s there would have been no exceedances on June 16,

2012, but for the presence of the natural events.

Section VII contains conclusions that summarize the exceptional even t that occurred on June 16, 2012,

and relates the requirements in the EER to the information within this document.

-ii-

## Table of Contents

I. EXCEPTIONAL EVENT RULE (EER) REQUIREMENTS ........................ 1

Procedural Requirements .................................................................................................... 1

Public notification that event was occurring (40 CFR 50.14(c)(1(i)) ................................ 1

Place informational flag on dat a in AQS (40 CFR 50.14(c)(2)(ii)) .................................... 1

Notify EPA of intent to flag th rough submission of initial event description by July 1 of

calendar year following event (40 CFR 50.14(c)(2)(iii)) .................................................... 1

Document that the public comment process was followed for event documentation (40 CFR

50.14(c)(3)(iv)) .................................................................................................................... 2

Submit demonstration supporting excepti onal event flag (40 CFR 50.14(a)(1-2)) ............ 2

Documentation Requirements ............................................................................................ 2



## II. CONCEPTUAL MODEL ................................................................................. 4

Geographic Setting and Climate ......................................................................................... 4

Geographic Setting of Monitors .......................................................................................... 4

Climate

............................................................................................................................... . 7

Monsoon Season Description and Event Summary .......................................................... 8

Conclusions ......................................................................................................................... 10



## III. HISTORICAL FLUCTUATIONS ............................................................... 14

Conclusions ......................................................................................................................... 17

Regulatory Measures and Control Programs .................................................................. 18

PM10 Rule Effectiveness ................................................................................................... 21

Compliance and Enforcement Activities .......................................................................... 22

Conclusions ......................................................................................................................... 23



## V. CLEAR CAUSAL RELATIONSHIP ............................................................ 25

Introduction ........................................................................................................................ 25

Event – June 16, 2012 ........................................................................................................ 25

Visibility Cameras .............................................................................................................. 34

Conclusion ........................................................................................................................... 34



## VI. “BUT FOR” ANALYSIS .............................................................................. 35

VII. CONCLUSIONS .......................................................................................... 36

Affects Air Quality ............................................................................................................. 36

Natural Event ..................................................................................................................... 36

Summary ............................................................................................................................. 37

-iii-

## List of Figures

Figure 2-1. Phoenix Geographi c Setting and PM10 Monitor Locations (source: EPA AQS

DataMart, NASA MODIS Satellite , Google Earth). PM10 monito r locations are indicated by

the white markers.

............................................................................................................................... ... 5

Figure 2-2. Drainage Syst em of Phoenix, Arizona. ......................................................................................6

Figure 2-3. Phoenix Monthly Precipitation (top) and Maxi mum Temperature (bottom)

Climatology (source: National Weather Service) ..................................................................................7

Figure 2-4. Cross-section of a thunderstorm creating an outflow boundary and haboob (Source:

Desert Meteorology. Thomas T. Warner. 2004.) ...................................................................................9

Figure 2-5. U.S. Drought Monitor an alysis released during the tim e period of the exceedances

described in this report. ........................................................................................................................11

Figure 2-6. Timeline of PM10 concen trations at monitors in the Phoenix area before, during and

after the June 16, 2012, event. ..............................................................................................................12

Figure 3-1. Plot of daily ma ximum hourly average PM10 concentrations (January 1, 2007 –

September 30, 2012) at the West Phoenix monitoring site. .................................................................14

Figure 3-2. Plot of 24-hour av erage PM10 concentrations (Ja nuary 1, 2007 – September 30, 2012)

at the West Phoenix monitoring site. ...................................................................................................15

Figure 3-3. Plot of daily ma ximum hourly average PM10 concentrations (January 1, 2007 –

September 30, 2012) at the Higley monitoring site. ............................................................................16

Figure 3-4. Plot of 24-hour av erage PM10 concentrations (Ja nuary 1, 2007 – September 30, 2012)

at the Higley monitoring site. ...............................................................................................................17

Figure 4-1. Timeline of Maricopa Count y Fugitive Dust Rules and Ordinances. ......................................22

Figure 5-1. Satellite imagery showing strong stor ms developing and dissipa ting over southeastern

Arizona. These storms are believed to have been responsible for th e thunderstorm outflow

boundary that caused PM10 exceedances in Maricopa and Pinal counties on June 16, 2012. ............26

Figure 5-2. Phoenix nonattainment area PM10 mon itor readings, Sky Harbor wind speed and

visibility, and Williams Gateway wind speed for June 16, 2012. ........................................................27

Figure 5-3. Pinal County PM10 monito r readings and Casa Grande wind speed and visibility for

June 16, 2012

............................................................................................................................... ........ 28

-iv-

## List of Tables

Table 2-1. Summary of Statewide PM10 Measurements for June 16, 2012. ..............................................13

Table 4-1. Rules and Ordinances Regulating Particulate Matter Emissions in Maricopa County .............19

Table 4-2. Pinal County Rules Regulating Existin g and New Non-point Sources in Pinal County ............20

Table 4-3. Pinal County Rules Regulating Fugitive Dust in Pinal County Portion of Maricopa

County PM10 Nonattainment Area ......................................................................................................21

-v-

### -vi

## List of Appendices

Appendix A – 5-year Historical Fluctuation Graphs for the Phoe nix Nonattainment Area PM10 Sites

Appendix B – ADEQ Forecast Products for P hoenix, Maricopa County, and Pinal County

Appendix C – Notice of Public Comment Period

Appendix D – National Weather Servic e Forecasts, Warnings, and Alerts

Appendix E – Additional National Weather Service Me teorological Data Tables for Maricopa County

Airports

## I. EXCEPTIONAL EVENT RU LE (EER) REQUIREMENTS

In addition to the technical requirements that are c ontained within the EER, proc edural requirements must

be met in order for EPA to concur with the flagged ai r quality monitoring data. This section of the report

lays out the requirements of the EER and associated guidance, and disc usses how the Arizona Department

of Environmental Quality (ADEQ) addressed those requirements.

Procedural Requirements

This section presents a review of the procedur al requirements of the EER as required by 40 CFR 50.14

( Treatment of Air Quality Monitoring Data Influenced by Exceptional Events ) and explains how ADEQ

fulfills them. The Federal EER requirements include notifying the public that an event was occurring,

placing informational flags on data in EPA’s Air Qua lity System (AQS), notifying EPA of the intent to

flag through submission of initial event descriptio n, documenting that the public comment process was

followed, and submitting a demonstration supporting th e exceptional events flag. ADEQ has addressed

all of these procedural and documentation requirements.

Public notification that event was occurring (40 CFR 50.1 4(c)(1(i))

ADEQ issued a Dust Control Action Forecast and an Ensemble Forecast for the Greater Phoenix area on

June 16, 2012, advising citizens of the general potential for blowing dus t due to very dry conditions.

More information on ADEQ’s forecasting program can be found in Section IV. The forecast products

that were issued for June 16, 2012, are included in Appendix B.

Place informational flag on data in AQS (40 CFR 50.14(c)(2)(ii))

ADEQ and other operating agencies in Arizona subm it da ta into EPA’s AQS. Data from both filter-based

and continuous monitors operated in Arizona are submitted to AQS.

When ADEQ and/or another agency operating monitors in Arizona suspect s that data may be influenced

by an exceptional event, ADEQ and/or the other opera ting agency expedites analysis of the filters

collected from the potentially affected filter-based ai r monitoring instruments, quality assures the results,

and submits the data into AQS. ADEQ and/or other operating agencies also submit data from continuous

monitors into AQS after quality assurance is complete.

If ADEQ and/or the operating agency have determined a potential exists that the monitor reading has been

influenced by an exceptional event, a preliminary fl ag is submitted for the measurement in the AQS. The

data are not official until they unde rgo more thorough quality assurance and quality control, leading to

certification by May 1 of the year following the ca lendar year in which the data were collected

(40 CFR 58.15(a)(2)). The presence of the flag can be confirmed in AQS.

Notify EPA of intent to flag through submission of in itial eve nt description by July 1 of calendar year

following event (40 CFR 50.14(c)(2)(iii))

ADEQ submitted notice to EPA on August 29, 2012 listing all days from calendar year 2012 that ADEQ

intends to analyze under the Exceptional Events Ru le and notifying the EPA of which PM10 data were

flagged in AQS. Exceedances that occurred on June 16, 2012, within the Phoenix PM10 nonattainment

area were included on that list. Th is report serves as the demonstra tion supporting the flagging of these

data.

-1-

### On June 16, 2012, seven monitoring sites within the boundaries of the Phoenix PM10 nonattainment area

exceeded th e 24-hour PM10 standard during the hi gh wind event that occurred during the late

afternoon/evening hours. The PM10 monitors impact ed were the Buckeye, Durango Complex, Dysart,

Higley, South Phoenix, West 43 rd 

### , and West Phoenix monitors operated by Maricopa County Air Quality

Department (MCAQD).

Document that the public comment proce ss was followed for event docu mentation (40 CFR

50.14(c)(3)(iv))

ADEQ posted this assessment report on the ADEQ webpage and placed a hardcopy of the report in the

ADEQ Records Management Center for public review . ADEQ will open a 30-day public comment period

on January 14, 2013. A copy of the public notice certification, along with any comments received, will be

submitted to EPA, consistent with the requirements of 40 CFR 50.14(c)(3)(iv). See Appendix D for a

copy of the affidavit of public notice.

Submit demonstration supporting exceptional event flag (40 CFR 50.14(a)(1-2))

At the close of the comment period, and after ADEQ has had the opportunity to consider any com ments

submitted on this document, ADEQ will submit this document, the comments received, and ADEQ’s

responses to those comments to EPA Region IX headqua rters in San Francisco, California. The deadline

for the submittal of this demons tration package is September 30, 2014.

Documentation Requirements

Section 50.14(c)(3)(iii) of the EER states that in order to jus tify excluding air quali ty monitoring data,

evidence must be provided for the following elements:

a. The event satisfies the criteria se t forth in 40 CFR 501(j) that:

(1) the event affected air quality,

(2) the event was not reasonably cont rollable or preventable, and

(3) the event was caused by human activity unlikely to recur in a particul ar location or was a

natural event;

b. There is a clear causal relations hip between the measurement under consideration an d the event;

c. The event is associated with a measured concentr ation in excess of normal historical fluctuations;

and

d. There would have been no exceedance or violation but for the event.

Section II of this assessme nt introduces the conceptual model of the high wind event that transpired on

June 16, 2012, providing a background narrative of the excepti onal events and an overall explanation on

how “the event affected air quality.” Further eviden ce that “the event affected air quality” is provided in

Section V. Sections II and V also provide evidence that the event was a natural event.

Section III of this assessment provides data summaries a nd time series graphs that help illustrate that the

event on June 16, 2012, produced PM10 concentrations in excess of normal hist orical fluctuations.

Section IV of this assessment details the existing area control measures and demonstrates that despite the

presence and enforcement of these controls, the event on June 16, 2012, was not reasonably controllable

or preventable.

-2-

### Section V of this assessm ent esta blishes a clear causal connection betw een the natural events of June 16,

2012, and the exceedances of the 24-hour PM10 standard at the monitoring stations. The evidence in this

section (and the previous section on hi storical fluctuations) also confir ms that the event in question both

affected air quality and were the result of natural events.

Section VI of this assessment builds upon the demons tration showing a clear causal connection between

the natural events and the exceedances and conclude s there would have been no exceedances on June 16,

2012, but for the presence of the natural events.

Section VII contains conclusions that summarize the exceptional even t that occurred on June 16, 2012,

and relates the requirements in the EER to the information within this document.

-3-

## II. CONCEPTUAL MODEL

Geographic Setting and Climate

This section describes the geographic and climatic setting of the monitors.

Geographic Setting of Monitors

Phoenix is located in the Salt R ive r Valley in south-central Arizona. It lies at a mean elevation of 1,090

feet above mean sea level (m sl) in the northeastern pa rt of the Sonoran Desert. Other than the mountains

in and around the city, the topography of Phoenix is ge nerally flat. The Phoenix area is surrounded by the

McDowell Mountains (~4,200 ft msl) to the northeast, the foothills of the Bradshaw (~7,900 ft msl) and

Mazataal (~7,900 ft msl) ranges to the north, the Wh ite Tank Mountains (~4,500 ft msl) to the west, the

Sierra Estrella (~4,450 ft msl) to th e southwest, and the Superstition Mo untains (~5,000 ft msl) far to the

east. Within the City are the Phoenix Mountains (~2,600 ft msl) and South Mountain (~2,600 ft msl).

Current development is pushing north, west, and south into Pinal County. The Phoenix metropolitan area

contains a fairly dense network of PM10 monitors throughout the area, with a much less dense network of

monitors located throughout the rest of the state. Figure 2-1 s hows the general geographic setting of

Phoenix, as well as the locations of PM10 monitors thr oughout the state. It should be noted that some of

the monitors shown in Figure 2-1 are filter-based mon itors; therefore, monitoring data from all locations

may be available only for select days (i.e., 1-in-6 run days).

-4-

### Figure 2-1. Phoenix Geographic Setting and PM10 Monito r Locations (source: EPA AQS DataMart,

NASA MODIS Satellite, Google Eart h). PM10 monitor locations ar e indicated by the white markers.

Figure 2-2 depicts the drainage system s or watersheds for the State of Arizona. Many of the rivers that

form Arizona’s drainage system are dry for most of th e year and, consequently, are sources of silt and fine

soils that become suspended and add to regional PM 10 loadings during high wind events. Much of this

alluvial matter and fine soil is deposited in the lo w lying areas of central a nd southern Arizona, with

larger depositional areas focused in and ar ound the confluences of dry river channels.

-5-

### Figure 2-2. Drainage System of Phoenix, Arizona.

-6-

### Climate

Phoenix has an arid climate, with very hot summers and temperate winters. The average summer high

temperature is among the hottest of any populated area in the United States. The temperature reaches or

exceeds 100oF an average of 110 days during the year and highs top 110oF an average of 18 days during

the year. Phoenix receives an average of 7.66 inches of rain per year.

As shown in Figure 2-3, precipitation is sparse during the first part of the summer, but the influx of

monsoonal moisture, which generally begins in early Ju ly and lasts until mid-Sept ember, raises humidity

levels and can cause heavy localized precipitation and flooding. Although thunderstorms are possible at

any time of the year, they are most common during the monsoon season from July to mid-September as

humid air is advected from the Gulf of California, Gulf of Mexico, a nd large thunderstorm complexes that

form over the Sierra Madre Occidental Mountains in Mexico. This influx of moisture, combined with

intense solar heating, often creates a very unstable environment that is ripe for thunderstorm development.

These thunderstorms can bring strong winds and blow ing dust, large hail, and heavy rain. Dust storms

associated with these thunderstorms typically occur in the ear ly part of the monsoon season

(June/July/August) before soaking rains help keep soil particles bound to one another. However,

depending on the amount of precipitation recei ved during the monsoon season, extremely hot

temperatures act to dry out the surface quickly, a nd dust storms can occur at any time. During the

December through March period, winter storms movi ng inland from the Pacific Ocean can produce

significant rains throughout Arizona. This Decemb er–March time period and the July–August time

period are typically the wettest part s of the year. Meanwhile, a distin ct dry season occurs from April

through June for the Phoenix area and the rest of Ar izona. While these weathe r patterns describe the

general climatology for the Phoenix area over a long period of time, P hoenix and the entire state of

Arizona are also prone to a high de gree of variability in these weathe r patterns from year to year.

Figure 2-3. Phoenix Monthly Precipitati on (top) and Maximum Temper ature (bottom) Climatology

(source: National Weather Service)

-7-

### Monsoon Season Description and Event Summary

A multi-day period, including the event day of June 16, 2012, was characterized by monsoonal

thunderstorm activity over southeas t Arizona and New Mexico. The No rth American Monsoon is a shift

in wind patterns in the summer that occurs as Mexi co and the southwest U.S. warm under intense solar

heating. As this happens, low level moisture is tr ansported primarily from th e Gulf of California and

eastern Pacific Ocean into the southwestern U.S. The Gulf of California, a narrow body of water

surrounded by mountains, is particular ly important for low-level moistu re transport into Arizona and

Sonora. Mid- and upper-level moisture is also tran sported into the region, ma inly from the Gulf of

Mexico by easterly winds aloft. This combination causes a distinct rainy s eason over large portions of

western North America, which develops rather quic kly and sometimes dramati cally. Rainfall during the

monsoon is not continuous and varies considerably, de pending on a variety of factors. There are usually

distinct “burst” periods of heavy rain during the monsoon, and “break” pe riods with little or no rain.

Even during active monsoon periods, some areas can go without receiving any significant precipitation

while other nearby areas experi ence heavy rains and flooding.

The thunderstorm activity in Arizona on June 16, 2012, was active in and around the desert areas of

southeastern Arizona. These thunderstorms did not re sult in any precip itation for the Phoenix area, but

the storms were severe in natu re and caused a dust-carry ing outflow boundary which propagated into the

Phoenix area in the evening. Downdrafts associated with heavy precipitation from thunderstorms or from

collapsing thunderstorms can end up producing what are called downbursts, or sometimes more

concentrated and severe microbursts, which are rapidly descending burst s of air that come through the

thunderstorms. These downward bursts of air hit the ground and then disperse away from the storms as

areas of outflow. These outflow boundaries from th e thunderstorms can kick up large areas of dust,

sometimes called haboobs, and trans port that dust for long distances from the initiat ing thunderstorms

(see Figure 2-4).

The active monsoon occurring on June 16 th 

### led to numerous thunderstorms and a large thunderstorm

outflow that produced blowing dust throughout southeastern and centr al Arizona, including the Phoenix

Metropolitan area. The windblown dust event produ ced seven PM10 exceedances in the Phoenix PM10

nonattainment area on June 16, 2012. The event was primarily driven by strong outflow winds from

severe thunderstorms produci ng wind gusts from one prominent direction. The June16 th 

### event was a

widespread dust event with mostly south-southeasterly winds transporti ng dust from the desert areas of

Pima and Pinal Counties into all areas of the Phoeni x region. Further details on the event can be found in

Section V.

-8-

### Figure 2-4. Cross-section of a thunderstorm creating an outflow boundary and haboob (Source: Desert

Meteorology. Thomas T. Warner. 2004.)

The nature of these monsoonal dust events is such that specific source areas are difficult to determine, as

outflows from thunderstorms can carry dust over va st distances encompassing many source areas.

Because of this, it is more appropriate to speak of general source regions for these monsoonal dust storms,

which typically are identified based upon the locations of the thunderstorms that are believed to have

created the dust generating and carrying outflow winds . The majority of the PM10 impacting the Phoenix

area from thunderstorm-driven high winds on June 16, 2012, originated outside of the Phoenix PM10

nonattainment area. The contributing source regions to the dust event were somewhat widespread, but a

large portion of the PM that was transported into Maricopa County lik ely came from areas within Pinal

County to the south and southeast of Maricopa C ounty. Other potential source contributors to the PM10

events were areas in northern Pima County and southeastern Maricopa County. The exact origin of the

PM sources is often difficult to determine due to the less dense monitoring networks in the general source

area.

Another important factor that le d to these significant dust storms was the on-going drought across the

region. The most recent U.S. Drought Monitor placed the area between Tucson and Phoenix, the primary

dust source region for winds out of the southeast, in D2 (Severe) to D3 (Extreme) drought (see Figure 2-

5). Rainfall in Phoenix since October 1, 2011, had b een 45% of normal, and only 11% of normal since

January 1, 2012 (see the Daily Climate Report for J une 16 in Appendix D). For additional general

information pertaining to the mons oon season in Arizona, see the news media web links provided below.

2011 Monsoon Season Summary and Review  http://bcove.me/krh3qk29

This video contains information about th e 2011 monsoon season and the general formation

of dust storms in Arizona, which is relevant each year.

-9-

### -10- 2011 Monsoon Season Review 2  http://bcove.me/tc6otk0h

This video contains information about the 2011 monsoon season, focusing on the large

number of dust storms that occurred, and a discussion of why there were so many dust

storms in 2011. Since similar meteorological factors were in place in 2012, dust storms

formed this year for many of the same reasons as they did in 2011.

The abnormally dry conditions that were in place dur ing the early part of the monsoon season (which

persisted throughout the duration of the monsoon season) resulted in a la rge fetch of soils that were

vulnerable to particulate suspension. The thundersto rm outflow boundaries that affected Maricopa and

Pinal counties on June 16, 2012, resulte d in very little rainfall throughou t south-central Arizona, but the

high winds associated with the outflow boundary did tran sport moderate to very hi gh levels of particulate

concentrations into the Phoenix area. A timeline summa rizing the June 16 event can be seen in Figure 2-

6. This figure shows hourly PM10 concentrations for a three-day period ar ound, and including, the event

day. During the 24 hours prior to the event, there were low PM10 c oncentrations across the Phoenix

region throughout the entire day. On the event day, the figure shows lo w PM10 concentrations during the

day and then very high PM10 con centrations during the evening hours when the thunderstorm outflow

boundary traveled through the Phoenix area. Lastly, the figure shows that PM10 concentrations gradually

dropped back down to low levels during the 24 hours af ter the event, indicating that without the impacts

of the thunderstorm outflow boundary, PM10 concentrations at all site s in the Phoenix PM10

nonattainment area on June 16, 2012, would have been below the 24-hour average PM10 exceedance

threshold of 150 μg/m 3



### .

Following Figure 2-6, Table 2-1 details the PM10 24- hour average concentrations, the daily maximum

hourly concentrations and the time at which they occurred, and the flag given to the data in EPA’s AQS

for all PM10 monitoring sites in Arizona for the ev ent day. The table shows exceedances of the national

24-hour PM10 standard at several si tes in Maricopa and Pinal Counties on June 16, 2012, and the timing

of the 1-hour maximum values across those sites i ndicates that PM10 was increasing sequentially from

the southeast to the northwest across central Arizona during the evening hours. This timing coincides

with a thunderstorm outflow boundary with sustaine d southeasterly winds ove r 30 miles per hour (mph)

that blew through Pinal County and into Marico pa County between 5 p.m. and 7 p.m. on June 16 th



### .

Conclusions

This Conceptual Model was created to provide a basic description of the general climate and weather

patterns that led to th e active thunderstorm period on June 16, 2012, and produced the dust storm and

seven PM10 exceedances in the Phoenix PM10 nonattainment area during the one-day episode. A more

detailed analysis of the windblown dus t event is included in Section V, where a demonstration of the clear

causal connection between the uncontrollable natu ral events and PM10 exceedances is presented.Figure 2-5.U.S. Drought Monitor analysisreleased during thetime period of the exceedances described in this report.-11-Figure 2-6.Timeline of PM10 concentrations at monitors in the Phoenix area before,during and after the June 16, 2012, event.-12-

### June 16, 2012

Table 2-1. Summary of Statewide PM10 Measurements for June 16, 2012.

Monitor Monitor

Type Operator AQS Monitor ID 24-hr Avg

PM10

(μg/m 3 ) 1-hr Max

PM10

(μg/m 3 ) Max

Time AQS

Qualifier

Flag

Apache County

N/A TEOM WMAT 04-001-1003-81102-1 24 148 1800

Cochise County

Paul Spur Chemical Lime Plant TEOM ADEQ 04-003-0011-81102-3 34 58 1500

Coconino County

N/A TEOM NN 04-005-1237-81102-1 N/A N/A N/A

Gila County

Hayden Old Jail TEOM ADEQ 04-007-1001-81102-3 83 581 1600 IJ

Maricopa County

Buckeye TEOM MC 04-013-4011-81102-1 202 1965 1900 RJ

Central Phoenix TEOM MC 04-013-3002-81102-4 97 990 1800

Durango Complex TEOM MC 04-013-9812-81102-1 186 2096 1800 RJ

Dysart TEOM MC 04-013-4010-81102-1 167 1269 1900 RJ

Fort McDowell/Yuma Frank TEOM FMIR 04-013-5100-81102-3 55 N/A N/A

Glendale TEOM MC 04-013-2001-81102-1 136 723 2000

Greenwood TEOM MC 04-013-3010-81102-1 145 1482 1800

Higley TEOM MC 04-013-4006-81102-1 194 2018 1800 RJ

JLG Supersite BAM ADEQ 04-013-9997-81102-3 118 1084 1800 IJ

JLG Supersite TEOM ADEQ 04-013-9997-81102-4 97 708 1800 IJ

North Phoenix BAM MC 04-013-1004-81102-1 74 596 1800

South Phoenix TEOM MC 04-013-4003-81102-1 165 1864 1800 RJ

Tempe TEOM MC 04-013-4005-81102-1 95 1018 1800

West Chandler TEOM MC 04-013-4004-81102-1 104 669 1700

West Forty Third TEOM MC 04-013-4009-81102-1 211 2299 1800 RJ

West Phoenix BAM MC 04-013-0019-81102-1 189 1945 1800 RJ

Zuni Hills TEOM MC 04-013-4016-81102-1 147 733 2100

Navajo County

N/A TEOM WMAT 04-017-1002-81102-1 N/A N/A N/A

Pima County

Ajo TEOM ADEQ 04-019-0001-81102-3 39 176 0500

Geronimo BAM PCDEQ 04-019-1113-81102-1 43 119 1500

Green Valley BAM PCDEQ 04-019-1030-81102-1 42 102 1400

Orange Grove FRM PCDEQ 04-019-0011-81102-2 38 N/A N/A

Rillito TEOM ADEQ 04-019-0020-81102-3 45 110 0100

South Tucson FRM PCDEQ 04-019-1001-81102-1 44 N/A N/A

Pinal County

Apache Junction Fire Stn. TEOM PCAQCD 04-021-3002-81102-3 66 655 1800

Casa Grande Downtown TEOM PCAQCD 04-021-0001-81102-3 235 2006 1700 RJ

Combs School TEOM PCAQCD 04-021-3009-81102-3 177 2683 1800 RJ

Cowtown TEOM PCAQCD 04-021-3013-81102-3 698 12276 1800 RJ

Maricopa TEOM PCAQCD 04-021-3010-81102-3 256 2405 1800 RJ

Pinal County Housing TEOM PCAQCD 04-021-3011-81102-3 541 6838 1700 RJ

Stanfield TEOM PCAQCD 04-021-3008-81102-3 339 5102 1800 RJ

Santa Cruz County

Nogales Post Office BAM ADEQ 04-023-0004-81102-3 55 125 1500

Yuma County

Yuma Supersite TEOM ADEQ 04-027-8011-81102-3 29 79 2300

Operator Abbreviations: MC – Marico pa County Air Quality Department

PCAQCD – Pinal County Ai r Quality Control District

ADEQ – Arizona Department of Environmental Quality

FMIR – Fort McDowell Indian Reservation

NN – Navajo Nation, AZ, NM, UT

PCDEQ – Pima County Department of Environmental Quality

SRP-MIC – Salt River Pima-Maricopa Indian Community of Salt River Reservation, AZ

WMAT – White Mountain Apache Tribe of Fort Apache Reservation, AZ



### -13-

## III. HISTORICAL FLUCTUATIONS

The PM10 concentrations measured across much of Maricopa County on June 16, 2012, were some of the

highest hourly and 24-hour averages m easured over the last five-plus years. Time series plots of the 24-

hour PM10 concentrations for the period January 1, 2007, through September 30, 2012, were created for

all PM10 monitors in the Phoenix PM10 nonattainment ar ea. Additionally, time series plots of the daily

maximum hourly average PM10 concentrations were created for two monitors in Maricopa County.

These two additional plots were created to provide a deeper understanding of the magnitude of short-term

particulate concentrations and their contri bution to PM10 exceedances in the Phoenix PM10

nonattainment area. Time series plots for two mon itoring sites (West Phoenix and Higley) are included

within this section, while the remaining 24-hour averag e plots are available in Appendix A. The West

Phoenix monitor was selected because of its central location in relation to all monitors in Maricopa

County and it was severely impacted site during th e June 16 windblown dust even t. The Higley monitor

was selected because it is representative of eastern Maricopa County, an area of the region frequently

impacted by dust storms caused by thunderstorm outflow events. The graphs below and in Appendix A

show that the June 16 th 

### event was in the top five most extreme events of the last five-plus years for

multiple sites.

Figure 3-1. Plot of daily m aximum hourly average PM10 concentrations (January 1, 2007 – September

30, 2012) at the West Phoenix monitoring site.

-14-

### Figure 3-1 shows the daily m aximum hourly averages from the West Phoenix PM10 monitor. The plot

shows that the June 16 th 

### hourly average of 1,945 μ g/m 3 

### was the second highest hourly PM10

concentration recorded in the last five-plus years. The plot also s hows that the maximum hourly average

PM10 concentration on June 16 was only second to that observed during the July 5, 2011, haboob event

which recently received EPA concurrence. The hourly average concentrations from this event surpassed

most of the dust storms that occurred during the 2011 monsoon season, which was one of the worst dust

storm seasons on record. It is also clear that the most significant hourly average PM10 concentrations at

the West Phoenix monitor typically occur during th e June through September time frame, a period during

which the monsoon season is most active and the Phoenix region is frequently impacted by haboob

events.

Figure 3-2 shows the daily 24-hour averages from the West Phoenix PM10 monitor and indicates that the

June 16 th 

### event produced the seventh highest 24-hour aver age PM10 concentration measured in the last

five-plus years. Similar to haboob events that oc curred in 2009 and during se veral months in 2011, the

June 16 th 

### event experienced PM10 concentrations that were well above the 24-hour exceedance threshold.

Figure 3-2. Plot of 24-hour average PM10 concentrations (January 1, 2007 – Septem ber 30, 2012) at the

West Phoenix monitoring site.

Figures 3-3 and 3-4 provide an hist orical look at the daily maximum hourly averages and daily 24-hour

averaged PM10 concentrations from the Higley monito r. The plots also show that the maximum hourly

concentration and exceedance measured at the Hi gley monitor on June 16 was among the 12 highest

PM10 concentrations measured over the last five-plu s years. As was the case for the West Phoenix

-15-

### monitor, the m ost significant hourly average PM10 con centrations at the Higley monitor typically occur

during the June through September time frame, a pe riod during which the mons oon season is most active

and the Phoenix region is frequently impacted by haboob events.

Figure 3-3. Plot of daily m aximum hourly average PM10 concentrations (January 1, 2007 – September

30, 2012) at the Higley monitoring site.

-16-

### Figure 3-4. Plot of 24-hour average PM10 concentrations (January 1, 2007 – Septem ber 30, 2012) at the

Higley monitoring site.

Conclusions

The plots within this section provi de an historical perspective of PM10 concentrations since 2007. These

plots, along with those in Appendix A, show that the haboob event that occurred on June 16, 2012,

resulted in one of the top 12 highest 24-hour average PM 10 concentrations seen in the last five-plus years

at multiple sites. This equates to PM10 concentrations in the 99.9 th 

### percentile when compared to historic

data. In the case of the West Phoenix and Dysa rt monitoring sites, th e 24-hour averaged PM10

concentrations measured on June 16 were in the top seven highest concentrations observed during the last

five-plus years. While the PM10 concentr ations that were measured on June 16 th 

### were extreme in many

cases, the plots also show that similar events are not uncommon during the monsoon season. As

documented in several published journals and acad emic text books, haboobs generated from thunderstorm

outflow boundaries are a phenomenon th at Arizona deals with every year, some years more so than

others, namely in 2007, 2009, and 2011.

-17-

## IV. NOT REASONABLY CONT ROLLABLE OR PREVENTABLE

Section 50.1(j) of Title 40 CFR Part 50 requires that an event must be “not reasonably controllable or

preventable” in order to be define d as an exceptional event. This requirement is met by demonstrating

that despite reasonable control measures in pl ace within Maricopa County and the Phoenix PM10

nonattainment area, high wind conditions overwhelmed all reasonably available controls. The event

occurring on June 16, 2012, was direc tly related to strong and gusty wi nds generated by a thunderstorm

outflow boundary. The strong winds overwhelmed all reasonably available cont rols, and were also

responsible for transporting PM into the Phoenix PM10 nonattainment area from areas outside of the

nonattainment area. As explained in the conceptu al model, downdrafts from collapsing thunderstorms

produce outflow boundaries that contai n gusty, turbulent wakes that rais e dust from the desert surfaces

that can be as wide as 100 miles in severe cases. As shown in Section V, the source region for all of the

dominant thunderstorm outflows a nd associated transported dust on June 16, 2012, generally came from

areas outside of the Phoenix PM10 nonattainment area—primarily from th e deserts of Pinal, Pima, and

southern Maricopa counties. Wh ile it is likely that some dus t was generated within the PM10

nonattainment area as gusts from the thunderstorm outflows passed through the area, the amount of dust

generated locally was easily ove rwhelmed by, and largely unnoticea ble as compared to, the dust

transported in from the source region s of the thunderstorm outflows. St rict controls on local sources of

fugitive dust were in place and enforced on June 16, 2012, but were not capable of controlling transported

dust and PM10 raised by the gusty and tur bulent thunderstorm out flows on this date.

The following sections describe the BACM- and MS M-level PM10 control measures in place June 16,

2012, and the robustness of the programs designed to enforce these measures. Pro-active response and

analysis of each event as it is occurring verify the uncontrollable nature of each event, while inspections

of local sources performed before, during, and afte r the June 16, 2012, event confirmed that no unusual

anthropogenic PM10-producing activities occu rred in Maricopa County, the Phoenix PM10

nonattainment area, or the local area s surrounding the exceeding monitors.

Regulatory Measures and Control Programs

ADEQ and MCAQD are responsible for implementing re gulatory measures to control emissions from

agricultural sources, stationary sources, fugitive dus t sources, and open burning within Maricopa County.

Three major programs provide or contribute to air pollution control measures for the Greater Phoenix

area:

1. ADEQ’s Agricultural Best Mana gement Program (AgBMP);

2. Maricopa County’s Inspection and Compliance Program; and

3. ADEQ’s Air Quality Forecasting Program.

Specifically, ADEQ is responsible for compliance assi stance and enforcement of Agricultural Best

Management Practices developed by the Governor’s Ag ricultural Best Management Practices Committee,

while MCAQD is responsible for compliance assura nce for all other significant sources of PM10

emissions. In addition to routine inspections and in spections driven by complaints, inspections are often

increased when (1) ADEQ forecasters issue a High Risk for the Maricopa County Dust Control Forecast,

(2) ADEQ forecasters issue a High Pollution Advisory, or (3) near-real-time monitoring data indicate

unique activity via high PM concentrations. Th e forecasting program a nd inspection/compliance

programs work together so that reso urces can be best utili zed during days that are of greatest risk for

elevated PM emissions.

-18-

### On July 25, 2002, EPA took initial action to finalize approval of the Best Av ailable Control Measure

(BACM) and the Most S tringent Measure (MSM) demons trations in the Serious Area PM10 plan for the

Maricopa County portion of the metropolitan Phoe nix PM10 nonattainment area (67 FR 48718). These

BACM and MSM demonstrations were again ap proved by EPA on July 14, 2006 (71 FR 43979). The

Agricultural Best Management Practices General Perm it rule and related definitions have been approved

into the Arizona Administrative Co de as R18-2-610 and R18-2-611 pursu ant to Arizona Revised Statutes

§ 49-457. 2 

### Maricopa County regulations of PM10 emissions are listed in Table 4-1.

Table 4-1. Rules and Ordinances Regulating Pa rticulate Matter Emissions in Maricopa County

Rule/Ordinance Number

& Title Description

Rule 300: Visible

Emissions Establishes standards for vi sible emissions and opacity.

Rule 310: Fugitive Dust

from Dust-Generating

Operations Establishes limits for the emissions of particulate matter into the

ambient air from any property, operations, or activity that may

serve as a fugitive dust source

Rule 310.01: Fugitive Dust

from Non-Traditional

Sources of Fugitive Dust Establishes limits for the emissions of particulate matter into the

ambient air from open areas, vacant lots, unpaved parking lots,

and unpaved roadways that are not regulated by Rule 310 and

that are not required to have ei ther a permit or a dust control

plan

Rule 311: Particulate

Matter from Process

Industries Establishes emission rates based on process weight applicable to

any affected operations not subject to Rule 316.

Rule 312: Abrasive

Blasting Establishes limits for particulate emissions from abrasive

blasting operations

Rule 314: Open Outdoor

Fires and Indoor Fireplaces

at Commercial and

Institutional Establishments Establishes limits for the emissions of air contaminants

produced from open burning

Rule 316: Nonmetallic

Mineral Processing Establishes limits for the emissions of particulate matter into the

ambient air from any nonmetallic mining operation or rock

product processing plant

Rule 317:

Hospital/Medical/

Infectious Waste

Incinerators Establishes limits for the emi ssions of air pollutants from

medical waste incinerators

Rule 322: Power Plant

Operations Establishes limits for the emissi ons of nitrogen oxides, sulfur

oxides, carbon monoxide and par ticulate matter from existing

power plants and cogeneration plants

Rule 323: Fuel Burning

Equipment from

Industrial/Commercial/

Institutional (ICI) Sources Establishes limits for the emissi ons of nitrogen oxides, sulfur

oxides, carbon monoxide and pa rticulate matter from ICI

sources

2 Updates to the AgBMP program in Decem ber, 2011, clarified BMPs for crop an d added BMPs for animal operations.

Effective 12/29/2011, R18-2-611 was renumbered to R18-2-610.01 Agricultural PM10 Gen eral Permit for Crop

Operations and R18-2-611.01 Animal Operations PM10 General Permit was added. Definitions for Crop Operations were

revised at R18-2-610, and new definitions for Animal Operations were added at R18-2-611.



### -19-

### Rule/Ordinance Number Description & Title

Rule 324: Stationary

Internal Combustion (IC)

Engines Establishes limits for the emissions of carbon monoxide,

nitrogen oxides, sulfur oxides , volatile organic compounds, and

particulate matter from stationary internal combustion engines,

including stationary IC e ngines used in cogeneration

Rule 325: Brick and

Structural Clay Products

(BSCP) Manufacturing Establishes limits for particulate matter emissions from the use

of tunnel kilns for curing in the brick and structural clay product

(BSCP) manufacturing processes

Ordinance P-25: Leaf

Blower Restriction Establishes restrictions for leaf blowers in incorporated and

unincorporated sections of Area A in Maricopa County

Ordinance P-26:

Residential Woodburning

Restriction Establishes restrictions for residential woodburning

Ordinance P-27: Vehicle

Parking and Use on

Unstabilized Vacant Lots Establishes restrictions fo r vehicle parking and use on

unstabilized vacant lots in unincor porated sections of Area A in

Maricopa County

Ordinance P-28: OffRoad Vehicle Use in

Unincorporated Areas of

Maricopa County Establishes restrictions fo r operating vehicles on unpaved

property in unincorporated areas of Maricopa County

Arizona Administrative

Code R18-2-611 & 610:

Agricultural PM10 General

permit Establishes a requirement for co mmercial farmers to implement

best management practices and maintain a record demonstrating

compliance

In addition to the rules and regul ations listed in Table 4-1, other PM10 reducing control measures (e.g.,

paving of unpaved roads, PM10 certified street sweep ers, controlling unpaved parking lots, etc.) have

been committed to, and implement ed by, local jurisdictions throughout the PM10 nonattainment area, and

incorporated into the Arizona SIP through PM10 pl ans such as the Revised MAG 1999 Serious Area

Particulate Plan for PM10 for the Maricopa County Nonattainment Area. The Pinal County Air Quality

Control District (PCAQCD) also implements regulat ory control measures on emissions from existing and

new non-point sources within Pinal County (see Tabl e 4-2). Additionally, the PCAQCD implements

specific nonattainment rules for that part of the P hoenix PM10 nonattainment ar ea that resides in Pinal

County (see Table 4-3).

Table 4-2. Pinal County Rules Regulating Existi ng and New Non-point Sources in Pinal County

Article Number & Title Description

Chapter 4, Article 2: Fugitive

Dust Provides a mechanism to reasona bly regulate operations which

periodically may cause fugitive dust emissions into the

atmosphere

Chapter 4, Article 3:

Construction Sites – Fugitive Dust Improves the control of excessive fugitive dust emissions that

have been traditionally associated with construction, earthwork,

and land development, and thereby minimize nuisance impacts

-20-

### Table 4-3. Pinal County Rules Regulating Fugitive Dust in Pinal County Portion of Maricopa

County PM10 Nonattainment Area

Article Number & Title Description

Chapter 4, Article 4:

Nonattainment Area Rules;

Dustproofing for Commercial

Parking, Drives and Yards Establishes rules to avoid viol ations of the prevailing PM10

standard and addi tionally minimize nuisance impacts by

improving control of excessive fugitive dust emissions from

unpaved parking lots

Chapter 4, Article 5:

Nonattainment Area Rules;

Stabilization for Residential

Parking and Drives Establishes rules for stabilizing residential properties

Chapter 4, Article 6: Restrictions

on Vehicle Parking and Use on

Vacant Lots Establishes rules for unpaved or unstabilized vacant lots (valid

in Pinal County portion of Area A)

Chapter 4, Article 7:

Construction Sites in

Nonattainment Areas – Fugitive

Dust Establishes rules to avoid viol ations of the prevailing PM10

standard and addi tionally minimize nuisance impacts by

improving control of excessive fugitive dust emissions from

activities associated with construction, earthwork, or land

development

Chapter 4, Article 8:

Nonattainment Area Rules,

Requirement for Stabilization of

Disturbed Areas at Vacant Lots Establishes rules for stabilizing disturbed areas at vacant lots

PM10 Rule Effectiveness

MCAQD analyzed the effectivenes s of its fugitive dust rules (Rul es 310, 310.01 and 316) in terms of

permit compliance rates. This ru le effectiveness (RE) study was de signed to assess how many sources

regulated by MCAQD during the subj ect time period received no PM10 emi ssions-related violations. As

a basis for comparison, the percentage of permitted s ources in compliance during calendar year 2007 was

76% for sources subject to Rule 310, 85% for Rule 310.01 sources, and 40% for Rule 316 sources. In

early 2008, Rules 310, 310.01, and 316 were strengthene d, and new ordinances (covering additional

source categories such as leaf blowers, vacant lots, and off-road vehicles) were adopted. These

enhancements resulted from MCAQD department’s obligations under such agreements as the 2005

Revised PM10 State Implementation Plan for the Sa lt River Area and the Maricopa Association of

Governments (MAG) 2007 Five Percent Plan for PM10 for the Maricopa County Nonattainment Area to

reduce PM10 emissions throughout the county. Thr ee major areas that contributed to increased

compliance were an increase in departmental staffing (especially inspectors), a robust training program,

and regulatory changes that broa dened and strengthened control measures under Rules 310, 310.01, and

316.

Source compliance rates were re-assessed for FY 2009 (July 2008–June 2009), a period that allowed time

for the new and revised regulations to take effect. The results showed significant increases in compliance

compared with the earlier period : to 90% (from 76%) for Rule 310 sources, to 95% compliance (from

85%) for Rule 310.01 sources, and to 65% (from 40 %) for Rule 316 sources. These improvements

continued into calendar year 2010 with compliance rates of 94% fo r Rule 310 sources, 96% for Rule

310.01, and 73% for Rule 316 sources. The timeline pr ovided in Figure 4-1 illustrates the improvements

-21-

### in RE over the last several years, and also points out signifi cant revisions to previ ous rules, as well as

newly adopted rules and ordinances.

0 1 / 27

/ 2 01

0

Rules 3 1 0 &

3 10.

0 1

R ev i s ed 0 1 / 1 2/

2 011

O rdinances

P ‐ 27

&

P

‐ 28

Revised 06/01/2005

06/08/20 0 5

Rule 3 1 6 Rev

is ed

04/

0 7/2004

R u le

3 10

Revised

0 2 /1

7 / 2 005

Rul

e 31

0 .01

Revised

0 3/26/200 8

R u les

31

0 &

3 10

.0 1 Revised

M arc h 20 08 S e p tem b er 200 6

0 2/

2 0/20 08

O rdina n ces

P ‐ 25,

P

‐ 27

&

P ‐ 2 8

Adopted

0 3/12/20 0 8

R u le

3 16

Revised



### Figure 4-1. Timeline of Maricopa County Fugitive Dust Rules and Ordinances.

Compliance and Enforcement Activities

MCAQD is prepared to proactively respond to high wind events and to protect human health and wellbeing. MCAQD’s approach consists of two primary co mponents: routine proactive inspections, as well

as surveillance inspections, conducted both during and after significant events. MCAQD routinely

inspects dust control-permitted sites and increases the frequency of inspections for permits covering areas

of 10 acres or more. Rule 316 sour ces are also regularly inspected mu ltiple times every year. Maricopa

County also responds to the majority of complaints within 24 hours.

Maricopa County monitors the ADEQ Five-Day Dust Control Forecast to iden tify the potential for

elevated PM10 pollution levels due to high winds or stagnant c onditions. When a High Pollution

Advisory (HPA) is issued for Maricopa County, MC AQD conducts additional surveillance before, during,

and after the forecast event(s). MCAQD also conducts event surveillance and pos t-event activities during

exceedance days that had not been forecast (i.e., thos e instances in which an HPA had not been issued).

Pre-event surveillance consists of surveying high-risk areas for any dust-generating activities, educating

sources of the impending HPA event, and issuing viola tions for failure to comply with local, state, or

federal regulations. During the event, MCAQD inspector s survey high-risk areas to confirm that control

measures are in place, document any violations, and contact other regulatory agen cies if necessary. Postevent activities include continued su rveys of high-risk areas, re-inspe cting sources that had received

violations within two business days, and an internal MCAQD debriefing of event activities.

During 2011 and 2012, a total of 17 MCAQD air monitoring sites were upgraded with new equipment to

allow the monitoring sites to automatically report monitored readings at five-minute intervals.

Previously, hourly readings were only available. The real-time data re porting system includes a

mechanism to alert MCAQD field staff when PM con centrations are elevated. The system allows

MCAQD responders to review concentr ations at the monitor and to c onsult the National Weather Service

website to check for weather event activity. This capability allows the MC AQD responder to identify

-22-

### regional events and m onitor specifi c issues. If necessary, the MC AQD responders can inform nearby

stakeholders and local governments of the elevated PM10 concentrations.

For June 16, 2012, a Maricopa County Dust Control Fo recast was issued by ADEQ indicating a low-risk

level for unhealthy PM 10 

### . The Dust Control Forecast stated mostly light winds were expected.

An evaluation of all inspection reports, air qua lity complaints, compliance reports, and other

documentation indicate no evidence of unusual anthropogenic-based PM 10 

### emissions. During the time

period of June 13 through June 19, 2012, MCAQD insp ectors conducted a total of 200 inspections of

permitted facilities, of which 97 were at fugitive dust sources. Additionally, MCAQD conducted 10

inspections on vacant lots and unpave d parking lots during this period.

During this 7-day period, a total of 13 vi olations were issued county-wide for PM 10 

### and non-PM 10 

### -related

violations. No violatio ns were issued for PM 10 

### emissions within a 4-mile radius of an exceeding monitor.

MCAQD was prepared for any complaints received due to the high wind event. During the 7-day period

from June 13 through June 19, 2012, MCAQD receive d 31 complaints, of which 23 were windblown

dust-related. Each complaint was assigned to and investigated by a MCAQD insp ector. A review of all

pertinent records from this period indicates that MCAQD inspectors did not observe any PM 10 

### emission

violations of local, state, or federal regulations within a 4-m ile radius of an exceeding monitor.

In addition to MCAQD’s efforts in pre-event surveillance and proact ive inspections, ADEQ’s

Agricultural Best Management Practice Program (Ag BMP) inspector monitors the ADEQ Five-Day Dust

Control Forecast and the MCAQD air monitoring sites that include real-time data. The ADEQ Ag BMP

inspector uses specific knowledge of seasonal activities and associa tions with the local growers and

dairymen to communicate the importance of limiting dust-generating activities, especially during highwind events. Additional outreach is conducted with facility representati ves prior to for ecasted high-wind

alert days. Should the PM10 readings at a MCAQD ai r monitoring site show notable increases, the

ADEQ Ag BMP inspector is dispatched to contact the owners and operators of ag riculture fields in the

area to discern if their activities ar e causing negative impacts. The Ag BMP inspector is prepared to

respond to most agriculture complaints within 24 hours.

Based on a review of the inspection reports and site visit documentation, there is no evidence to suggest

that agricultural activ ities produced unusual PM10 emissions . On June 15, 2012, the ADEQ Ag BMP

inspector observed activity in the Higley area and not ed no harvesting or tilling activities. The inspector

also noted a straw cuttings fire in the area of 27 th 

### Avenue and South Mountain road was extinguished by

local fire agency. No complaints were re ceived in the 2 days prior to the event.

Conclusions

The thunderstorm outflow event of June 16, 2012, first described in Section II and discussed in more

detail in Section V, produced strong gusts and tur bulent wakes that transpor ted dust and PM10 into the

Phoenix PM10 nonattainment area. The source region of the outflows that caused the exceedances was

largely located in areas outside the Phoenix PM10 nonattainment area, primarily the deserts of Pinal,

Pima, and southern Maricopa County. The Phoenix area is designated as a seriou s nonattainment area for

PM10 and is required to have BACM for all si gnificant sources of PM10. BACM-approved control

measures on significant anthropogenic sources were in place and enforced during the events, and proactive tracking and response to th e events by regulatory agencies and local governments confirmed the

uncontrollable nature of the dust emi ssions; therefore, these pre-existing/ prior approved required controls

-23-

### are adequ ate for meeting the requirements of an ex ceptional event and should be considered “reasonable”

for these purposes.

Despite the deployment of comprehensive control m easures and sophisticated response programs and a

few localized, low-impact violati ons of the dust control rules, hi gh wind conditions associated with

thunderstorms and thunderstorm outflows brought high concentrations of PM10 emissions into, and also

overwhelmed controls within, the Phoenix PM10 nonattainment area. Strong thunderstorm outflows with

sustained winds ranging from 20-30 mph, and even greate r speeds nearest the source regions, described in

Section V, were enough to overwhelm all available e fforts to limit PM10 concentrations from the event.

The fact that these were natura l events involving strong thunderstorm outflow wi nds that transported

PM10 emissions into Maricopa County, with a majo rity of the PM10 emissions recorded by Maricopa

County area monitors coming from s ources outside of the Phoenix PM 10 nonattainment area, provides

strong evidence that the events and exceedances of June 16, 2012, recorded within the Phoenix PM10

nonattainment area, were not reasonab ly controllable or preventable.

-24-

## V. CLEAR CAUSAL RELATIONSHIP

Introduction

A demonstration of the clear causa l connection between uncontrollable natural events or uncontrollable

emissions associated with thunderstorm outflow s and PM10 exceedances on June 16, 2012, is presented

in the following time series graphs, infrared satell ite imagery, and National Weather Service (NWS) data

tables for selected, representative airports. These various pieces of information contain data on sustained

wind speed, wind speed gusts, PM10 c oncentrations, visibility, weathe r observations, and thunderstorm

development areas and provide the causal connection between the uncont rollable emissions associated

with thunderstorm outflows and elevated PM10 concentrations. For reference, Appendix D provides

additional NWS text products issued preceding and on June 16 containing forecasts and warnings of

blowing dust due to thun derstorms outflows. A summary of the event day is provided below.

Event – June 16, 2012

On June 16, 2012, the Phoenix region experienced typical summertime weather conditions with a

maximum temperature of 106°F, relative humidity of 10-20%, winds <6 miles per hour (mph) from

various directions for much of the day, and visibility at 10 miles all day, as reported at the Phoenix Sky

Harbor Airport. Broad high pre ssure over the southwestern U.S. limited thunderstorm development and

kept winds light on the June 15 th 

### , causing PM10 concentrations to be generally low (20-80 μg/m 3 

### range)

on the day preceding the dust event and through the early afternoon on June 16 th 

### , despite prevalent dry

conditions due to very little rain over the previous few months. Betw een 3 p.m. Mountain Standard Time

(MST) and 5 p.m. MST on June 16, se vere thunderstorms developed over a limited portion of Arizona to

the southeast of the Phoenix region (as shown in Figure 5-1) and by 6 p.m., outflows from the

thunderstorms entrained dust from de sert areas of Pinal County and ge nerated a “haboob” that progressed

northwestward into Maricopa County, transporting large amounts of PM10. As shown in Figure 5-2, the

“haboob” had the following impacts in the Phoenix ar ea: southeasterly winds increased to 21-25 mph,

with gusts up to 32 mph; visibility dropped from 10 miles to 0.75 miles; weathe r conditions were reported

as “blowing dust”; and hourly PM10 concen trations increased to nearly 2,300 μg/m 3 

### at the West 43 rd



### monitoring site and exceeded 1400 μg/m 3 

### at six sites. Once the winds subsided during the 7 p.m. hour,

PM10 concentrations remained high for several hours, resulting in 24-hour average concentrations above

180 μg/m 3 

### at five monitoring sites on June 16. In total, seven monitoring sites in the region exceeded the

PM10 NAAQS and, as was mentioned in the Historical Fluctuation section, most of those seven PM10

monitoring sites saw one of their 12 highest 24-hour average PM10 concen trations measured in the past

five years. Without the existence of the emission s generated by the thunderst orm outflows, there would

not have been any exceedances of the 24-hour PM10 standard in the Phoenix PM10 nonattainment area.

-25-

### 11:00 a.m

. 2:00 p.m. 4:00 p.m. 6:00 p.m.

1800z Jun 16 2100z Jun 16 2300z Jun 16 0100z Jun 17

8:00 p.m. 10:00 p.m. 12:00 a.m. 2:00 a.m.

0300z Jun 17 0500z Jun 17 0700z Jun 17 0900z Jun 17

Figure 5-1. Satellite imagery showing strong storms de veloping and dissipating over southeastern

Arizona. These storms are believed to have been responsible for the thunders torm outflow boundary that

caused PM10 exceedances in Maricopa and Pinal counties on June 16, 2012.

Figure 5-2 depicts the dust event th at occurred in Maricopa County im pacting the Phoenix area on June

16, 2012. Hourly averaged PM10 concentrations at monitors throughout Maricopa County are shown

along with visibility readings (b lue diamonds) and wind speeds repor ted at the Phoenix Sky Harbor

Airport. Measurements at Sky Harbor were used due to its central location am ongst most of the monitors

that experienced exceedances on June 16. Wind speeds for the Mesa Williams Gateway Airport on the

eastern-side of the Phoenix region were also included on the graph. As ca n be seen in the graph, visibility

was reduced down to 0.75 miles at the Sky Harbor Airport during the windblown dust event, and this

visibility reduction coincide d with rapidly increasing PM10 concentrations and sustained wind speeds up

to 25 mph in the Phoenix area. The NWS data tables after Figure 5-3 also show reports of blowing dust

during the 6 p.m. hour, when PM10 concentrations we re the highest. Additiona lly, the NWS issued dust

storm warnings (see Appendix D) for many areas in Pinal and Maricopa Counties due to the large haboob

that was moving across southeastern and central Arizona for upwards of 100 miles. The daily

climatology report June 16 th 

### also listed under “Weather Conditions” for the day: “Sandstorm”, providing

another clear indication of an exceptional natural event.

-26-

### Figure 5-2. Phoenix nonattainm ent area PM10 monitor readi ngs, Sky Harbor wind speed and visibility,

and Williams Gateway wind speed for June 16, 2012.

As shown in Figure 5-3, several monitoring sites in the upwind, dust source region of Pinal County

measured 24-hour average PM10 exceedances, with the peak site (Cowtown) ha ving a 24-hour average of

698 μg/m 3 

### and an extremely high maximum 1-hour average during the 5 p.m. hour of 12,276 μg/m 3



### , when the southeasterly winds were st rongest and the visibility was lowest at the Casa Grande Airport (see

the NWS data tables below). Two other monitoring sites also measured hourly concentrations over 5,000

μg/m 3 

### . These spikes at the Pinal County monitors preceded the PM10 concentration spikes at the

monitoring sites in Ma ricopa by one to two hours, which is cons istent with wind speeds and directions

observed at the Phoenix Sky Harbor Airport in Maricopa County and th e Casa Grande Airport in Pinal

County for the propagation of the haboob across the regi on. Only monitoring sites in Maricopa and Pinal

counties exceeded the NAAQS due to thunderstorm outfl ows on this day, but the broad range of sites and

the extreme hourly- and daily-averaged PM10 concen trations reflect the magnitude of the haboob.

Additionally, the NWS airport meteor ological data tables for the Phoe nix Sky Harbor and Casa Grande

airports show that the strongest wi nds associated with the haboob were out of the southeast. These winds,

combined with the high PM10 concen trations in Pinal County, indicate that PM10 was already entrained

in the atmosphere outside of the Phoenix PM10 nonatta inment area and then transported into the region

by the strong winds.

-27-

### Figure 5-3. Pinal County PM10 m onitor readin gs and Casa Grande wind speed and visibility for June 16,

2012

A visualization of this dust event wa s created using Phoenix visibility camera images that can be viewed

as an animation here:

Looking south toward Phoenix, with South Mountain in the distance:

www.phoenixvis.net/videos/ m peg4/SOMT_06162012.mp4

The video clearly shows the wall of dust blowing across the Phoenix regi on in the early evening of June

16, 2012. The snapshot on the cover of this report wa s taken from the 6:10 p.m. mark of the video and

coincides with the PM10 concentration spikes seen in the 5-minute data from the PM10 monitoring sites

in the central Phoenix area. Videos showing other vi ews across the Valley on this date are also available

(see Visibility Cameras section).

-28--29-U.S. Department of CommerceNational Oceanic & Atmospheric AdministrationQUALITY CONTROLLED LOCALCLIMATOLOGICAL DATA(final)HOURLY OBSERVATIONS TABLEPHOENIX SKY HARBORINTL AIRPORT (23183)PHOENIX, AZ(06/2012)National Climatic Data CenterFederal Building151 Patton AvenueAsheville, North Carolina 28801Elevation: 1107 ft. above sea levelLatitude: 33.427Longitude: -112.003Data Version: VER3DryBulbTempWetBulbTempDewPointTempDateTime(LST)StationTypeSkyConditionsVisibility(SM)WeatherType(F)(C)(F)(C)(F)(C)RelHumd%WindSpeed(MPH)WindDirWindGusts(MPH)StationPressure(in. hg)PressTendNet3-hrChg(mb)SeaLevelPressure(in. hg)ReportTypePrecip.Total(in)Altimeter(in. hg)1234567891011121314151617181920212223161616161616161616161616161616161616161616161616161616161616005101510251035104510551065107510851095110511151125113511451155116511751180718111815181918281835185119512051215122512351111111111111111111111111111111111111111111111111111111111111CLRCLRCLRCLRCLRFEW180 SCT250FEW180 SCT250FEW200 SCT250FEW200 SCT250FEW200 SCT250SCT200 SCT250SCT200 SCT250FEW200 SCT250FEW120 SCT200 SCT250FEW120 SCT200 SCT250FEW120 SCT200 SCT250FEW120 SCT200 SCT250FEW120 SCT200 SCT250FEW018 SCT120 SCT200BKN018BKN020BKN022BKN025 BKN120 BKN200SCT030 SCT120 SCT200FEW035 SCT120 SCT200SCT120 SCT200 SCT250SCT120 SCT200 SCT250FEW120 SCT200 SCT250FEW120 SCT200 SCT250FEW120 SCT200 SCT25010.0010.0010.0010.0010.0010.0010.0010.0010.0010.0010.0010.0010.0010.0010.0010.0010.0010.001.001.000.751.002.503.008.0010.0010.0010.0010.0010.00BLDUBLDUBLDU87858483807882859093969810110210310310610410210010099999997969595939130.629.428.928.326.725.627.829.432.233.935.636.738.338.939.439.441.140.039.038.038.037.037.037.036.135.635.035.033.932.860585857565657585961626365666666666567676767676766666565646515.414.614.214.013.413.314.014.115.015.816.717.418.218.618.618.619.018.419.319.319.319.419.419.419.018.618.518.317.918.23735343434363532313234363839383837364345454646464645454444472.81.71.11.11.12.21.70.0-0.60.01.12.23.33.93.33.32.82.26.07.07.08.08.08.07.87.27.26.76.78.317171717192218151211111111111111991315151616161717181718228796503360555350131518242121222221143035270290310310220000240200VR000310VRVRVR0100001401601701701601601301401501402600001600903032323131312928.5828.5928.6128.6228.6428.6628.6628.6928.6828.6828.6828.6628.6428.6228.6028.5628.5728.5828.5928.6028.6028.6028.6028.6128.6228.6228.6428.6628.6828.663336851301301801400301801901901729.6829.7029.7129.7329.7529.7629.7829.7929.7929.7829.7829.7829.7529.7329.7029.6729.6729.68MMMMMM29.7229.7329.7429.7629.7829.77AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAASPSPSPSPSPSPAAAAAAAAAAAA29.7529.7629.7829.7929.8129.8329.8429.8629.8529.8529.8529.8429.8129.7929.7729.7329.7429.7529.7629.7729.7729.7729.7729.7829.7929.7929.8129.8329.8529.84Dynamically generated Wed Dec 26 21:52:51 EST 2012 viahttp://cdo.ncdc.noaa.gov/qclcd/QCLCD-30-U.S. Department of CommerceNational Oceanic & Atmospheric AdministrationQUALITY CONTROLLED LOCALCLIMATOLOGICAL DATA(final)HOURLY OBSERVATIONS TABLEWILLIAMS GATEWAY AIRPORT (23104)PHOENIX, AZ(06/2012)National Climatic Data CenterFederal Building151 Patton AvenueAsheville, North Carolina 28801Elevation: 1382 ft. above sea levelLatitude: 33.3Longitude: -111.666Data Version: VER2DryBulbTempWetBulbTempDewPointTempDateTime(LST)StationTypeSkyConditionsVisibility(SM)WeatherType(F)(C)(F)(C)(F)(C)RelHumd%WindSpeed(MPH)WindDirWindGusts(MPH)StationPressure(in. hg)PressTendNet3-hrChg(mb)SeaLevelPressure(in. hg)ReportTypePrecip.Total(in)Altimeter(in. hg)12345678910111213141516171819202122231616161616161616161616161616161616161616161616161616161616161600150035005501150135015502150235025503150335035504150435045505150547074708470947104711471347144715471720174718251847194719550000000000000000000000000000000CLRCLRCLRCLRCLRCLRCLRCLRCLRCLRCLRCLRCLRCLRCLRCLRSCT120 SCT200SCT120 SCT200SCT120 BKN200FEW100 SCT200FEW100 SCT200FEW100 SCT200SCT120SCT120SCT120SCT012SCT120SCT120SCT120 BKN200BKNSCT10010.0010.0010.0010.0010.0010.0010.0010.0010.0010.0010.0010.0010.0010.0010.0010.0035.0035.0035.0035.0035.0035.0035.0030.0030.000.50s1.003.0010.0020.0010.00DSsBLDUBLDU828281817979777777777777777777757384889397102102106106104999797979528.028.027.027.026.026.025.025.025.025.025.025.025.025.025.024.023.029.031.034.036.039.039.041.041.040.037.036.036.036.035.05958606056565656555555555555565554606162636565676767676666M6614.714.315.315.313.513.113.313.312.712.712.712.712.712.713.112.812.415.515.916.517.318.218.219.219.219.619.319.019.0M18.6393743433634373734343434343436373741393737373739394346464648464.03.06.06.02.01.03.03.01.01.01.01.01.01.02.03.03.05.04.03.03.03.03.04.04.06.08.08.08.09.08.02220262621202424212121212121232527221814121111101013161717M1955755776676765055003665931723292398200170110100100090130100090100100110090090000120090000000VR310350VR310VR18016013013012014030393428.3328.3428.3428.3428.3428.3528.3628.3628.3728.3728.3728.3828.3828.3928.3928.4028.4128.4328.4328.4328.4228.4128.4028.3428.3228.3628.3728.3728.37M28.38MMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA29.7929.8029.8029.8029.8029.8129.8229.8229.8329.8329.8329.8429.8429.8529.8529.8629.8729.8929.8929.8929.8829.8729.8629.8029.7829.8229.8329.8329.8329.8329.84-31-1616161616161616161616161620152035204720552115213521552215223522552315233523550000000000000CLRCLRBKNCLRCLRCLRCLRCLRCLRCLRCLRCLRCLR10.0010.0020.0010.0010.0010.0010.0010.0010.0010.0010.0010.0010.009395939393919393919090908834.035.034.034.034.033.034.034.033.032.032.032.031.06566M6565646464636364646318.318.6M18.118.117.717.717.717.317.117.517.517.2464646454545434343434545458.08.08.07.07.07.06.06.06.06.07.07.07.02019M19192018181919212122887756005503312014014016014017000000024027000036033028.3828.37M28.3828.3928.4028.4228.4228.4228.4328.4228.4328.43MMMMMMMMMMMMMAAAAAAAAAAAAAAAAAAAAAAAAAA29.8429.8329.8329.8429.8529.8629.8829.8829.8829.8929.8829.8929.89Dynamically generated Wed Dec 26 22:18:53 EST 2012 viahttp://cdo.ncdc.noaa.gov/qclcd/QCLCD-32-U.S. Department of CommerceNational Oceanic & Atmospheric AdministrationQUALITY CONTROLLED LOCALCLIMATOLOGICAL DATA(final)HOURLY OBSERVATIONS TABLECASA GRANDE MUNICIPAL ARPT (03914)CASA GRANDE, AZ(06/2012)National Climatic Data CenterFederal Building151 Patton AvenueAsheville, North Carolina 28801Elevation: 1462 ft. above sea levelLatitude: 32.95Longitude: -111.766Data Version: VER2DryBulbTempWetBulbTempDewPointTempDateTime(LST)StationTypeSkyConditionsVisibility(SM)WeatherType(F)(C)(F)(C)(F)(C)RelHumd%WindSpeed(MPH)WindDirWindGusts(MPH)StationPressure(in. hg)PressTendNet3-hrChg(mb)SeaLevelPressure(in. hg)ReportTypePrecip.Total(in)Altimeter(in. hg)12345678910111213141516171819202122231616161616161616161616161616161616161616161616161616161616161600150035005501150135015502150235025503150335035504150435045505150535055506150635065507150735075508150835085509150935095510150000000000000000000000000000000CLRCLRCLRCLRCLRCLRCLRCLRCLRCLRCLRCLRCLRCLRCLRCLRCLRCLRCLRCLRCLRCLRCLRCLRCLRCLRCLRCLRCLRCLRCLR10.0010.0010.0010.0010.0010.0010.0010.0010.0010.0010.0010.0010.0010.0010.0010.0010.0010.0010.0010.0010.0010.0010.0010.0010.0010.0010.0010.0010.0010.0010.008179757577757373727072727272727273707273757779818286889090919127.026.024.024.025.024.023.023.022.021.022.022.022.022.022.022.023.021.022.023.024.025.026.027.028.030.031.032.032.033.033.05757555556555454545254545454545454525454565757575960616161626214.113.712.812.613.212.612.212.211.911.111.911.911.911.911.911.912.211.112.112.413.213.714.114.114.715.515.916.316.316.516.5373737363736363636343636363636363634373739393937393939393939393.03.03.02.03.02.02.02.02.01.02.02.02.02.02.02.02.01.03.03.04.04.04.03.04.04.04.04.04.04.04.021222524242426262727272727272727262728272726242122191817171616076000005303650005300030000605500022020000000000000000003004000003001002000000000004004000000000022000000000000032000025017028.2528.2428.2528.2528.2728.2728.2728.2728.2728.2728.2828.2828.2828.2928.2928.3028.3128.3128.3228.3228.3328.3428.3428.3428.3428.3428.3428.3428.3428.3428.34222010010017MMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA29.7929.7829.8029.8029.8129.8129.8129.8129.8229.8229.8329.8329.8329.8429.8429.8529.8629.8629.8729.8729.8829.8929.8929.8929.8929.8929.8929.8929.8929.8929.89-33-16161616161616161616161616161616161616161616161616161616161616161616161616161616161035105511151135115512151235125513151335135514151435145515151535155516151635165517151735175518151835185519151935195520152035205521152135215522152235225523152335235500000000000000000000000000000000000000000CLRCLRCLRCLRCLRCLRCLRCLRCLRCLRCLRCLRCLRCLRCLRCLRCLRCLRCLRCLROVC010BKN010CLRCLRCLRCLRCLRCLRCLRCLRCLRCLRCLRCLRCLRCLRCLRCLRCLRCLRCLR10.0010.0010.0010.0010.0010.0010.0010.0010.0010.0010.0010.009.0010.0010.0010.0010.0010.0010.0010.000.251.753.002.003.0010.0010.0010.0010.0010.0010.0010.0010.0010.0010.0010.0010.0010.0010.0010.0010.00919393959797999910010010010010210010210210210210210299979593919191919191919190908888868484818133.034.034.035.036.036.037.037.038.038.038.038.039.038.039.039.039.039.039.039.037.036.035.034.033.033.033.033.033.033.033.033.032.032.031.031.030.029.029.027.027.0626262636464666667676667676767676767676766666665646464646464646464646363636263616116.516.916.917.318.018.018.718.719.319.318.919.319.619.319.619.619.619.619.619.619.119.018.618.317.917.917.917.917.917.917.917.717.517.717.417.417.016.617.116.016.039393939414143434545434545454545454545454546464646464646464646454546464646464846464.04.04.04.05.05.06.06.07.07.06.07.07.07.07.07.07.07.07.07.07.08.08.08.08.08.08.08.08.08.08.07.07.08.08.08.08.08.09.08.08.016151514141415151515141514151414141414141617192021212121212121202122232325272929290675335756097813111307732s282224201613875578760350350003603602502502602602502002600000202902902802802700002001601101201201101100900901001601401301201301501300001600900000200402020161746383436282828.3428.3428.3428.3328.3228.3228.3128.3028.3028.2928.2828.2728.2728.2528.2528.2428.2428.2528.2528.2528.2728.2728.2728.2828.2828.2928.2928.2928.2928.2928.3028.3028.3128.3228.3228.3228.3328.3328.3428.3328.344772000020010014MMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA29.8929.8929.8929.8829.8729.8729.8629.8529.8529.8429.8329.8229.8129.8029.7929.7829.7829.7929.7929.8029.8229.8229.8229.8329.8329.8429.8429.8429.8429.8429.8529.8529.8629.8729.8729.8729.8829.8829.8929.8829.89Dynamically generated Wed Dec 26 21:48:16 EST 2012 viahttp://cdo.ncdc.noaa.gov/qclcd/QCLCDA description of the fields anddata codes/abbreviations used inthese tables can be found here:http://cdo.ncdc.noaa.gov/qclcd/qclcddocumentation.pdf

### Visibility Cameras

Visibility camera images were comp iled into time lapse photo graphy videos in order to visually show the

dust impacts on portions of Maricopa County on June 16. The animations are available online for each

event and for each of the visibility camera sites in Maricopa County. These views can be accessed using

the camera site codes SOMT (South Mountain), CA ME (Camelback Mountains), SUPM (Superstition

Mountains), ESMO (Estrella Mountai ns), and WHTM (White Tank Mountains). It should be noted that

these time lapse photography videos may requi re the installation of a mp4 viewer.

The video files can be accessed as follows:

http://www.phoenixvis.net/videos/mpeg4/xxxx_mmddyyyy.mp4

xxxx = 4-character site code (ie. SOMT)

mm = 2-character month (ie. 06)

dd = 2-character day (ie. 16)

yyyy = 4-character year (ie. 2012)

Conclusion

The information presented within this section has adequately demonstrated a clear causal relationship

between the emissions generated by uncontrollable natu ral events and the exceedances measured at the

monitors. The satellite images, time series graphs, and meteorological data tables provided in this section

show the temporal progression of the dust events from the developm ent of the thunderstorms, to the

increase in wind speeds, and to th e rise in PM10 concentrations. Th e combination of the PM10 and wind

data from Maricopa and Pinal counties shows the tr ansport of particulate ma tter from the south through

Pinal County and into the Phoenix PM10 nonattainment area. This information supports the conclusion

that the events were primarily caused by windblown dust from emissi on sources outside of Maricopa

County and the transport of PM10 into the Phoenix PM10 nonattainment area.

-34-

## VI. “BUT FOR” ANALYSIS

Section 50.14(c)(3)(iv)(D) in 40 CF R part 50 requires that an excep tional event demonstration must

satisfy that “[t]here would have been no exceedance or violation but for the event.” The prior sections of

this submittal have provided detailed informa tion that the exceedances on June 16, 2012, were not

reasonably controllable or preventa ble and there is a clear causal re lationship between transported PM10

from thunderstorm outflows originating in the dese rt areas outside of the Phoenix PM10 nonattainment

area and the measured exceedances w ithin the nonattainment area. Th e weight of evidence in these

sections demonstrates that but for the existence of emissions generated by thes e thunderstorm outflows

and associated transported PM10, there would have been no exceedances of the 24-hour PM10 standard.

As detailed in Section IV, all r easonable control measures were in place and actively enforced before,

during, and after the exceedances of June 16, 2012. Inspection and compli ance data of local fugitive dust

sources during this time period revealed that PM10 from anthropogenic activities was well controlled and

constant. Local regulatory agencies , industry, and the general public we re alerted to the possibility of

dust storms due to thunderstorm activ ity through daily forecasts and medi a reports. Heightened, real-time

surveillance of PM10 monitoring stati ons during the events established a clear link between rapidly rising

PM10 concentrations and the arrival of the thunderstorm outflows. On-the-ground observations recorded

during the events consistently iden tify transported or re-entrained PM10 as the cause of the elevated

concentrations near the exceeding monitors.

As shown in Section V, detailed, time series data establish a clear causal rela tionship between the arrival

of emissions generated by thunders torm outflows and elevated PM10 c oncentrations at the monitors.

Multiple, independent measurements of wind speed, wind di rection, and visibility a ll point to the presence

of thunderstorm outflows as the delivery vehicle fo r transported PM10 into the nonattainment area. Any

local PM10 emissions generated during the arrival of the thunderstorm outflows are linked to the

turbulent and gusty outflow front of the storm and pa le in comparison to the amount of transported PM10

originating outside the nonattainme nt area. The source region for the primary thunderstorm outflow

boundary and transported PM10 are clearl y identified as the desert areas to the southeast of the Phoenix

PM10 nonattainment area.

The body of evidence presented in this submittal provide s no alternative that coul d tie the exceedances of

June 16, 2012, to any other causal source but trans ported and re-entrained PM10 generated from

thunderstorm outflows, confirming th at there would have been no exceedances but for the presence of

these uncontrollable natural events.

-35-

## VII. CONCLUSIONS

The exceedances that occurred on June 16, 2012, satisfy the following criteria of 40 CFR 50.1(j) and meet

the definition of an exceptional event:

 The event affects air quality;

 The event is not reasonably cont rollable or preventable; and

 The event is unlikely to reoccur at a partic ular location or [is] a natural event.

Affects Air Quality

As stated in the preamble to the Exceptional Events Rule, the event in question is considered to have

affected air quality if it can be shown that there is a clear causal relationship between the monitored

exceedance and the event, and that the event is associ ated with a measured concentration in excess of

normal historical fluctuations. Give n the information presented in Sect ions II, III, IV, and V, we can

reasonably conclude that the even t in question affected air quality.

Not Reasonably Controllable or Preventable

Section 50.1(j) of Title 40 CFR Part 50 requires that an event must be “not reasonably controllable or

preventable” in order to be define d as an exceptional event. This requirement is met by demonstrating

that, despite reasonable control measures in pl ace within Maricopa County and the Phoenix PM10

nonattainment area, high wind conditions overwhelmed all reasonably available controls. Despite the

deployment of comprehensive control measures and sophisticated response programs, high wind

conditions associated with thunderstorms and thunde rstorm outflows brought hi gh concentrations of

PM10 emissions into, and also overwhelmed controls within, the Phoenix PM10 nonattainment area. The

event discussed in this document that caused the exceed ances in this request (see Sections II and V) were

caused by thunderstorm-driven outflow winds that tr ansported dust into Maricopa County from areas

largely outside of the Phoenix PM10 nonattainment ar ea. The fact that thes e were natural events

involving strong thunderstorm outflow winds that tr ansported PM10 emissions into Maricopa County,

with a majority of the PM10 emissions recorded by Maricopa County area monitors coming from sources

outside of the Phoenix PM10 nonattainment area, provides strong evidence that the event and

exceedances of June 16, 2012, recorded within the nonatt ainment area were not reasonably controllable or

preventable.

Natural Event

As discussed above, the events shown to cause thes e exceedances were emissions of PM10 driven by high

winds caused by thunderstorm activity and related outflow boundary on June 16, 2012. The events

therefore qualify as natural events.

-36-

### -37- Summary

In summary, the exceedances of the federal 24- hour PM10 standard on June 16, 2012, would not have

occurred but for the monsoonal t hunderstorm-driven high winds and windblown dust transport from areas

largely outside the Phoenix PM10 nonattainment area , based on the weight of evidence summarized

below.

 Graphs of PM10 at various Phoenix area monitors in Section V and the tables containing

meteorological data for representative NWS airpor t sites show that the timing of elevated PM10

events was consistent with decreased visi bility and high winds at the NWS sites.

 Visibility camera imagery discussed in Sec tion V indicates that la rge quantities of PM10 were

transported into the Phoenix Metro area during the June 16 th 

### event. The timing of the dust storms

depicted in the visibility camera imagery is consistent with the PM10 concentration

measurements, elevated winds, and reduced visibility reported du ring the event.

 Historical Fluctuation analyses and graphs in Section III and Appendix A showing five years of

24-hour average data for each of the Phoenix PM 10 nonattainment area monitors depict numerous

atypically high PM10 concentrations on June 16, 2012. The sudden increase in the frequency of

elevated PM10 concentrations during this time peri od was exceptional from an historical

perspective.

 Each of the exceedances of the PM10 standard recorded on June 16 is tied to thunderstorm activity

and thunderstorm generated outflow winds, as can be seen in data and analyses in Section V.

 Figures and tables in Section V show that the timing of the thunderstorm-generated outflow

boundary passage, and increases in wind speeds at the monitoring locations and National Weather

Service stations during this event, is c onsistent with the timing of elevated PM10 concentrations

recorded at the monitoring locations in the Phoenix PM10 nonattainment area.

 Wind directions, thunderstorm-generated out flow boundary propagation, and concentration

patterns showing elevated levels of PM10 in Pinal County prior to leve ls increasing in Maricopa

County, all depicted in Section V, help show that the majority of the dust which impacted Phoenix

PM10 nonattainment area monitors originated in Pina l County and other areas located generally to

the south of the Phoenix PM10 nonattainment area.

 Section IV discusses rules that are in place in the Phoenix PM10 nonattainment area as well as

inspections that were conducted in the area to veri fy compliance with those rules in order to show

that the events are not reasonably controllable or preventable. Additionally, the visibility webcam

time lapse photography videos referenced in Secti on V help illustrate the magnitude and scale of

these events, which supports the claim that the exceedances recorded during this period were not

reasonably controllable or preventable.

## APPENDIX A

5

- YEAR HISTORICAL FLUCTUATION GRAPHS FOR

THE PHOENIX PM10 NONATTAINMENT AREA MONITORING SITES0

50 100 150 200 250 300 350 400 450 500

PM 10 Concentration ( μg/m 3 )



### Date Buckeye 5

- Year Historical Fluctuation

- 24 Hour Averages0

50 100 150 200 250 300 350 400 450 500

PM 10 Concentration ( μg/m 3 )



### Date West Phoenix 5

- Year Historical Fluctuation

- 24 Hour Averages0

50 100 150 200 250 300 350 400 450 500

PM 10 Concentration ( μg/m 3 )



### Date West 43rd 5

- Year Historical Fluctuation

- 24 Hour Averages0

50 100 150 200 250 300 350 400 450 500

PM 10 Concentration ( μg/m 3 )



### Date South Phoenix 5

- Year Historical Fluctuation

- 24 Hour Averages0

50 100 150 200 250 300 350 400 450 500

PM 10 Concentration ( μg/m 3 )



### Date Durango 5

- Year Historical Fluctuation

- 24 Hour Averages0

50 100 150 200 250 300 350 400 450 500

PM 10 Concentration ( μg/m 3 )



### Date Higley 5

- Year Historical Fluctuation

- 24 Hour Averages0

50 100 150 200 250 300 350 400 450 500

PM 10 Concentration ( μg/m 3 )



### Date Dysart 5

- Year Historical Fluctuation

- 24 Hour Averages

## APPENDIX B

ADEQ F ORECAST PRODUCTS FOR PHOENIX

, MARICOPA COUNTY, AND PINAL COUNTY

## MARICOPA COUNTY DUST CONTROL FORECAST

ISSUED FRIDAY, JUNE 15, 2012

Three-day weather outlook:

Mostly light winds are expected through the weekend and into next week, as high pressure begins to build over the

region from the south. Daytime temperatures will soar abov e 110°F by Sunday. Moisture will increase next Thursday

and Friday, a precursor our thunderstorms/dust storm season. With desert soil getting very dry, distant thunderstorms

present an increased risk of blowing dust here in the Valley. It’s just a matter of time. For now, the risk of exceeding

the 24-hr PM10 health standard in Phoenix is forecast to be Low through Wednesday of next week.

RISK FACTORS

WINDS STAGNATION UNHEALTHY PM-10

RISK LEVEL

Day 1: Sat 06/16/2012 Mostly light winds are

expected. + Rather stagnant

conditions are likely

early, improving late. = 

### LOW

Day 2: Sun 06/17/2012 Mostly light winds are

expected. + Rather stagnant

conditions are likely

early, improving late. = 

### LOW

Day 3: Mon 06/18/2012 West winds between

5 and 15 mph are

expected, gusting

near 20 mph at times. + Slightly stagnant

conditions are likely

early, improving late. = 

### LOW

EXTENDED OUTLOOK

Day 4: Tue 06/19/2012 Mostly light winds are

likely. + Rather stagnant

conditions are likely

early, improving late. = 

### LOW

Day 5: Wed 06/20/2012 Mostly light winds are

likely. + Rather stagnant

conditions are likely

early, improving late. = 

### LOW

The Maricopa County Dust Control Action Forecast is issued to assist in the planning of work

activities to help reduce dust pollution. A reco rded message of this forecast can be accessed at

602-771-2368 . To review the complete air quality forecast for the Phoenix metropolitan area,

as well as the health impacts and reduction methods for different air pollutants, call 602-771-

2367 for recorded forecast information or click on ADEQ's Air Quality Forecast at

http://www.azdeq.gov/environ/ air/o zone/ensemble.pdf

.

JRP 04/28/2011VERY UNHEALTHY (201-300)

UNHEALTHY (151-200)

UNHEALTHY FOR SENSITIVE GROUPS (101-150)

MODERATE (51-100)

GOOD (0-50)

For more information visit:

http://www.airnow.gov/index.cfm?action=aqibasics.aqi

*LINK TO 2011 AIR POLLUTION EXCEEDANCE GRAPH* 

### AIR QUALITY FORECAST FOR SATURDAY, JUNE 16, 2012

This report is updated by 1:00 p.m. Sunday thru Friday and is valid

for areas within and bordering Maricopa County in Arizona

* O3 = Ozone CO = Carbon Monoxide PM-10 = Particles 10 microns & smaller PM-2.5 = Particles smaller than 2.5 micro ns

*“ Ozone Health Watch ” means that the highest concentration of OZONE may approach the federal health standard.

“ PM-10 or PM-2.5 Health Watch ” means that the highest concentration of PM-10 or PM-2.5 may approach the federal health standard.

“ High Pollution Advisory ” means that the highest concentrati on of OZONE, PM-10, or PM-2.5 may exceed the federal health standard.

“ DUST ” means that short periods of high PM-10 concentrations caused by outflow from thunderstorms are possible. FORECAST

DATE

NOTICES

(*SEE BELOW

FOR DETAILS)

AIR POLLUTANT 

### YESTERDAY

THU 06/14/2012

Highest AQI Reading/Site

(* Preliminary data only *) 

### TODAY

FRI 06/15/2012 

### TOMORROW

SAT 06/16/2012 

### EXTENDED

SUN 06/17/2012



### O3* 42

CAVE CREEK 64

MODERATE 48

GOOD 51

MODERATE



### CO* 5

GREENWOOD 8

GOOD 6

GOOD 6

GOOD



### PM-10* 54

SOUTH PHOENIX 46

GOOD 45

GOOD 44

GOOD



### PM-2.5* 28

WEST PHOENIX 34

GOOD 31

GOOD 30

GOODHealth Statements

Friday, 06/15/12 Unusually sensitive people should consider limiting prolonged or heavy

exertion outdoors.

Saturday, 06/16/12 No health impacts are expected.

SYNOPSIS AND DISCUSSION

MONITORING SITE MAPS

STATIC MAP http://www.azdeq.gov/environ/air/monitoring/images/map.jpg

http://aqwww.maricopa.gov/AirMonitoring/SitePollutionMap.aspx

http://156.42.96.39/alert/Google/air.html INTERACTIVE MAPS

http://www.airnow.gov/



### POLLUTION MONITOR READINGS FOR TH URSDAY, JUNE 14, 2012



### O3 (OZONE)

Info on current 8-hour ozone standard: http://www.epa.gov/air/ozonepollution/pdfs/2008_03_aqi_changes.pdf

For archived AQI maps go to: http://www.airnow.gov/index.cfm?action=airnow.maps

SITE NAME MAX 8-HR VALUE (PPB) MAX AQI AQI COLOR CODE

Alamo Lake 44 37

Apache Junction 40 34

Blue Point 43 36

Buckeye 38 32

Casa Grande 36 31

Cave Creek 50 42

Central Phoenix 38 32

Dysart 42 36

Falcon Field 37 31

Fountain Hills 41 35

Glendale 43 36

Humboldt Mountain 40 34

North Phoenix 44 37

Phoenix Supersite 44 37

Pinal Air Park 38 32

Queen Valley 45 38

Rio Verde 44 37

South Phoenix 40 34

South Scottsdale 42 36

Tempe 39 33

Tonto Nat’l Mon. 45 38 Air quality levels will remain pretty good throug h the weekend. It’s t he heat that will be the

biggest concern. Daytime highs will soar abov e 110°F Sunday through early next week as high

pressure builds over the region from the south. Winds will continue to be relatively light. Ozone

may rebound early next week as winds shift back out of the southwest.

PM10 levels have slipped into the lower Moderate range while winds remain very light. This

is an indication that the desert soil is very dry now, with the top layer ready for liftoff. By next

Thursday and Friday, we’ll start to feel moisture levels increase as high pressure finds its way

near the Four Corners. This gets us one step closer to our thunderstorm season. It also raises

the likelihood of large dust storms impacting local PM10 levels. We are now on notice.

Check back on Sunday for a look ahead at next week’s weather and air quality. Until then,

have a great weekend! -J.PaulWest Chandler 37 31

West Phoenix 42 36

Yuma 46 39



### CO (CARBON MONOXIDE)

SITE NAME MAX 8-HR VALUE (PPM) MAX AQI AQI COLOR CODE

Central Phoenix 0.2 2

Greenwood 0.4 5

West Phoenix 0.3 3



### PM-10 (PARTICLES)

SITE NAME MAX 24-HR VALUE (μg/m3) MAX AQI AQI COLOR CODE

Apache Junction 37.5 35

Buckeye 48.2 44

Central Phoenix 41.2 38

Combs School (Pinal County) 72.6 60

Durango 49.1 45

Dysart 31.9 29

Glendale 29.7 27

Greenwood 45.4 41

Higley 43.2 39

Maricopa (Pinal County) 64.7 56

North Phoenix 32.8 30

Phoenix Supersite 31.1 28

South Phoenix 61.8 54 HIGHEST LOCALLY

Tempe 35.8 33

West Chandler 43.2 39

West Forty Third 59.1 53

West Phoenix 41.2 38

Zuni Hills 27.0 25



### PM-2.5 (PARTICLES)

(Some data derived from light-scattering equipment)

For maps go to : http://www.airnow.gov /

SITE NAME MAX 24-HR VALUE (μg/m3) MAX AQI AQI COLOR CODE

Durango 7.0 23

Dysart 5.2 17

Estrella Mountain Park 4.5 15

Glendale 5.5 18

Phoenix Supersite 3.6 12

North Phoenix 8.6 28

South Phoenix 5.4 18

Tempe 6.0 19

Vehicle Emissions Lab 4.0 13

West Phoenix 8.5 28



### LOCAL AIR POLLUTANTS IN DETAIL

O3 (OZONE) :Description

– This is a secondary pollutant that is formed by th e reaction of other primar y pollutants (precursors)

such as VOCs (v olatile o rganic c ompounds) and NOx (N itrogen Ox ides) in the presence of heat

and sunlight.

Sources – VOCs are emitted from motor vehicles, chemical plants, refineries, factories, and

other industrial sources. NOx is emitted from motor vehicles, power plants, and other sources of

combustion.

Potential health impacts – Exposure to ozone can make people more susceptible to respiratory

infection, result in lung inflammation, and aggr avate pre-existing respiratory diseases such as

asthma. Other effects include decrease in lung function, chest pain, and cough.

Unit of measurement – Parts per billion (ppb).

Averaging interval – Highest eight-hour period within a 24-hour period (midnight to midnight)

Red uction tips – Curtail daytime driving, refuel cars a nd use gasoline-powered equipment as late in

the day as possible.



### CO (CARBON MONOXIDE) :

Description – A colorless, odorless, poisonous gas formed when carbon in fuels is not burned

completely.

Sources – In cities, as much as 95 percent of all CO emissions emanate from automobile exhaust.

Other sources include industrial processes, non-transportation fuel combustion, and natural

sources such as wildfires. Peak concentr ations occur in colder winter months.

Potential health impacts – Reduces oxygen delivery to the body’s organs and tissues. The health

threat is most serious for those who suffer from cardiovascular disease.

Unit of measurement – Parts per million (ppm).

Averaging interval – Highest eight-hour period within a 24-hour period (midnight to midnight)

Red uction tips – Keep motor vehicle tuned properly and minimize nighttime driving.



### PM-10 & PM-2.5 (PARTICLES) :

Description – The term “particulate matter” (PM) includes both solid particles and liquid droplets

found in air. Many manmade and natural sources emit PM directly or em it other pollutants that

react in the atmosphere to form PM . Particles less than 10 micrometers in diameter tend to pose

the greatest health concern because they can be inhaled into and accumulate in the respiratory

system. Particles less than 2.5 micrometers in diam eter are referred to as “fine” particles and are

responsible for many visibility degradations such as the “Valley Brown Cloud” (see

http://www.phoenixvis.net/ ). Particles with diameters between 2.5 and 10 micrometers are referred

to as “coarse”.

Sources – Fine = All types of combustion (motor vehicles, power plants, wood burning, etc.) and

some industrial processes. Coarse = crushing or grinding operations and dust from paved or

unpaved roads.

Potential health impacts – PM can increase susceptibility to respiratory infections and can

aggravate existing respiratory diseases, such as asthma and chronic bronchitis.

Units of measurement – Micrograms per cubic meter (ug/m3)

Averaging interval – 24 hours (midnight to midnight).

Reduction tips – Stabilize loose soils, slow down on dirt roads, carpool, and use public transit.

{ Updated 12/19/2011 }

## APPENDIX C

NOTICE OF PUBLIC COMMENT PERIOD

## A PPENDIX D

NATIONAL WEATHER SERVICE FORECASTS,

WARNINGS, AND ALERTS

### 149

CDUS45 KPSR 170821

CLIPHX

CLIMATE REPORT

NATIONAL WEATHER SERVICE PHOENIX AZ

121 AM MST SUN JUN 17 2012

...................................

...THE PHOENIX AZ CLIMATE SUMMARY FOR JUNE 16 2012...

CLIMATE NORMAL PERIOD 1981 TO 2010

CLIMATE RECORD PERIOD 1895 TO 2012

WEATHER ITEM OBSERVED TIME RECORD YEAR NORMAL DEPARTURE LAST

VALUE (LST) VALUE VALUE FROM YEAR

NORMAL

................................ .................................. TEMPERATURE (F)

YESTERDAY

MAXIMUM 106 451 PM 115 1974 104 2 105

1896

MINIMUM 78 552 AM 54 1907 78 0 78

1897

AVERAGE 92 91 1 92

PRECIPITATION (IN)

YESTERDAY 0.00 0.01 1930 0.00 0.00 0.00

MONTH TO DATE 0.00 0.00 0.00 0.00

SINCE OCT 1 2.38 5.32

- 2.94 2.78

SINCE JAN 1 0.36 3.21

- 2.85 1.04

SNOWFALL (IN)

YESTERDAY 0.0

MONTH TO DATE 0.0

SINCE JAN 1 0.0

SINCE JUL 1 0.0

SNOW DEPTH 0

DEGREE DAYS

HEATING

YESTERDAY 0 0 0 0

MONTH TO DATE 0 0 0 0

SINCE JUN 1 0 0 0 0

SINCE JUL 1 837 935

- 98 893

COOLING

YESTERDAY 27 26 1 27

MONTH TO DATE 415 384 31 349

SINCE JUN 1 415 384 31 349

SINCE JAN 1 1467 1270 197 1213

..................................................................

### WIND (MPH)

HIGHEST WIND SPEED 28 HIGHEST WIND DIRECTION SE (140)

HIGHEST GUST SPEED 33 HIGHEST GUST DIRECTION SE (140)

AVERAGE WIND SPEED 5.9

SKY COVER

AVERAGE SKY COVER 0.3

WEATHER CONDITIONS

THE FOLLOWING WEATHER WAS RECORDED YESTERDAY.

HAZE

SANDSTORM

RELATIVE HUMIDITY (PERCENT)

HIGHEST 21 600 AM

LOWEST 9 600 PM

AVERAGE 15

..........................................................

THE PHOENIX AZ CLIMATE NORMALS FOR TODAY

NORMAL RECORD YEAR

MAXIMUM TEMPERATURE (F) 105 114 1896

MINIMUM TEMPERATURE (F) 78 54 196 5

1944

1923

SUNRISE AND SUNSET

JUNE 17 2012..........SUNRISE 518 AM MST SUNSET 740 PM MST

JUNE 18 2012..........SUNRISE 518 AM MST SUNSET 740 PM MST

- INDICATES NEGATIVE NUMBERS.

R INDICATES RECORD WAS SET OR TIED.

MM INDICATES DATA IS MISSING.

T INDICATES TRACE AMOUNT.

&&

.....................................................................

DEW POINT

HIGHEST DEW POINT 47

LOWEST DEW POINT 31

AVERAGE DEW POINT 38

.....................................................................

$$

995

FXUS65 KPSR 161033

AFDPSR

### AREA FORECAST DISCUSSION

NATIONAL WEATHER SERVICE PHOENIX AZ

330 AM MST SAT JUN 16 2012

.SYNOPSIS...

PRIMARILY HOT AND DRY WEATHER WILL CONTINUE ACROSS MUCH OF THE

REGION THROUGH AT LEAST THE MIDDLE OF NEXT WEEK. A FEW THUNDERSTORMS

WILL BE POSSIBLE LATE THIS AFTERNOON AND EVENING ACROSS FAR

SOUTHEAST ARIZONA...HOWEVER A LACK OF MOISTURE MAY LIMIT ANY FURTHER

MOVEMENT TO THE NORTH AND WEST. TEMPERATURES WILL BEGIN CLIMBING

AGAIN TODAY...REACHING NEAR OR ABOVE 110 DEGREES ON SUNDAY AND

MONDAY FOR LOW DESERT LOCATIONS. THE ABNORMALLY HOT WEATHER WILL

CONTINUE THROUGH MOST OF NEXT WEEK.

&&

.DISCUSSI ON...

THE WELL ADVERTISED CUTOFF LOW FEATURE WILL CONTINUE TO RETROGRADE

TO THE SOUTHWEST OFF THE BAJA COAST...INTO THE PACIFIC FOR THE NEXT

SEVERAL DAYS AS STRONGER RIDGING STEADILY INTENSIFIES OVER THE

DESERT SOUTHWEST AND FOUR CORNERS REGION. IN THE INTERIM...SATELLITE

IMAGERY INDICATES A SUBTLE VORTICITY CENTER CROSSING INTO THE GULF

OF CALIFORNIA WITH BACKING SOUTHERLY FLOW IN THE H8

- H5 LAYER. WATER

VAPOR LOOPS SHOW SOME INCREASE IN ATMOSPHERIC MOISTURE CONTENT

PULLING NORTH AHEAD OF THIS VORT C ENTER...THOUGH THE BEST DEEP

MOISTURE REMAINS RELEGATED TO THE CONTINENTAL DIVIDE AND POINTS

EAST. CONVECTIVE REMNANTS AND MESOSCALE OUTFLOW INITIATED LAST

EVENING IN THE EL PASO VICINITY HAS PUSHED SOMEWHAT BETTER LOW LEVEL

MOISTURE WESTWARD THROUGH F AR SOUTHWEST NEW MEXICO WHERE DEWPOINTS

HAVE INCREASED INTO THE MIDDLE/UPPER 40S...THOUGH JUST ENTERING FAR

SOUTHEAST ARIZONA WHERE KDUG REMAINS WITH LOWER 30 DEWPOINTS.

BOTH OPERATIONAL AND HIGH RESOLUTION DIRECT CONVECTIVE ALLOWING

MODELS HAVE VARYING SOLUTIONS REGARDING CONVECTIVE EVOLUTION THIS

AFTERNOON AND EVENING. GIVEN THE SYNOPTIC ENVIRONMENT WITH DEEP

SOUTHERLY FLOW...CONCEPTUALLY WOULD EXPECT ELEVATED HIGH TERRAIN

CONVECTION TO BLOSSOM ACROSS SOUTHEAST ARIZONA THIS AFTERN OON...AND

HAVE DISCOUNTED MODELS WITH LACK OF CONVECTIVE RESPONSE (I.E. LOCAL

6KM NMM CORE). AT THE OTHER END OF THE SPECTRUM...A DRIER WESTERLY

FETCH IN THE LOW TERRAIN REGIONS OF CENTRAL ARIZONA SHOULD LIMIT THE

EXTENT OF ORGANIZED CONVECTIVE PROPAGA TION TO THE NORTHWEST...AND

HAVE ELIMINATED MODELS SHOWING PRECIPITATION IN THIS AREA (I.E. GFS

CORES). HAVE MOSTLY UTILIZED SREF PROBABILISTIC OUTPUT ALONG WITH

THE OPERATIONAL NAM AND THE NCEP 4KM WRF

- NMM HIGH RESOLUTION MODEL

TARGETING FAR SOUTHEAST ARIZONA THROUGH WEST CENTRAL NEW MEXICO WITH

THE STRONGEST SIGNALS FOR PERSISTENT CONVECTION.

THESE AREAS JUST OUTSIDE THE SOUTHERN AND EASTERN PERIPHERY OF THE

FORECAST AREA SHOULD BE CHARACTERIZED BY MUCAPES EXCEEDING 500

J/KG...DEEPLY MIXED BOUNDA RY LAYERS WITH MIXING RATIOS NEAR 6

G/KG...AND CLASSIC INVERTED

- V SOUNDINGS WITH CLOUD BASES AROUND

600MB. SREF PROBABILITIES FOR CONVECTIVE 0.01 PRECIP TOTALS

JUXTAPOSED WITH MIDLEVEL UVV AND THUNDERSTORM GUIDANCE ARE

UNQUESTIONABLY HIGH...YIELDING BE TTER CONFIDENCE IN THESE AREAS FOR

AT LEAST SOME ORGANIZED THUNDERSTORMS. MEAN FLOW VECTORS FROM THE

S/SW IN THE MAJORITY OF THE CLOUD BEARING LAYER SHOULD ALLOW

### ELEVATED CONVECTIVE ELEMENTS TO PROPAGATE TOWARDS GILA

COUNTY...THOUGH ECHOES MAY REMAIN P RIMARILY VIRGA...AND HAVE KEPT

JUST A MEAGER MENTION OF POPS AT THE HIGHEST ELEVATIONS. GIVEN THE

HIGH CLOUD BASES AND LARGE DCAPE VALUES ON THE WESTERN EDGE OF THE

THETA

- E GRADIENT...STILL CANNOT RULE OUT THAT OUTFLOW GENERATION

COULD STIR UP BLOWING DUST INTO PINAL AND NORTHEAST MARICOPA

COUNTIES. HOWEVER...CONFIDENCE IN THIS SCENARIO IS STILL TOO LOW TO

INTRODUCE INTO THE GRIDDED DATABASE.

BY SUNDAY...THE INFLUENCE OF THE CUTOFF SYSTEM WILL LARGELY HAVE

DRIFTED WESTWARD...WITH MUCH STRONGER SUBSIDENCE ALOFT AND A

PREVAILING WESTERLY FETCH SHUNTING ANY DIURNAL CONVECTION WELL TO

THE EAST. H5 HEIGHTS WILL RAPIDLY INCREASE AOA 588DM WITH H7

TEMPERATURES IN A +12C TO +15C RANGE...YIELDING HIGHS MUCH ABOVE

AVERAGE. HAVE KEPT THE FORECAST FOR LOWER ELEVATIONS IN A 105F

- 115F

RANGE...WITH THE MAJOR METROPOLITAN AREAS STILL JUST SHORT OF

EXCESSIVE HEAT CRITERIA. NEVERTHELESS...THE PERSISTENCE AND

MAGNITUDE OF THE HEAT SHOULD NOT BE TAKEN LIGHTLY...AND WILL

MAINTAIN MENTIONS IN THE HAZARDOUS WEATHER OUTLOOK AND WEBPAGE.

HEIGHTS AND TEMPERATURES ALOFT WILL BE DAMPENED SLIGHTLY ON TUESDAY

AS A WAVE PASSES THROUGH THE NRN/CNTRL ROCKIES...HOWEVER THIS WILL

ONLY BE A TEMPORARY REPRIEVE...AS STRONG RIDGING BUILD S RAPIDLY OVER

THE FOUR CORNERS REGION WITH H5 HEIGHTS EXCEEDING 590DM BY

WEDNESDAY. HAVE STAYED SOMEWHAT CONSERVATIVE FORECASTING HIGHS

EITHER SIDE OF 110F FOR THE LAST SEVERAL DAYS OF THE WEEK...AGAIN

STILL JUST SHORT OF EXCESSIVE HEAT CRITERIA. IF T HE RIDGE CENTER

BECOME SITUATED CLOSER TO THE FORECAST AREA AND COMPRESSIONAL

EFFECTS MORE PRONOUNCED...THEN THE FORECAST HIGHS MAY NEED TO BE

INCREASED CLOSER TO WARNING THRESHOLDS.

&&

.AVIATION...

SOUTH

- CENTRAL ARIZONA...INCLUDING KPHX...KIWA...AND KSDL...

THROUGH 20Z SAT...CLEAR SKIES LIGHT WIND UNDER 10 KNOTS.

SOUTHEAST CALIFORNIA AND SOUTHWEST ARIZONA INCLUDING KIPL AND KBLH...

THROUGH 20Z SAT...CLEAR SKIES AND LIGHT WIND UNDER 10 KNOTS.

AVIATION DISCUSSION NOT UPDATED FOR AMENDED TAFS.

&&

.FIRE WEATHER...

MONDAY THROUGH FRIDAY...

A STRONG UPPER RIDGE WILL BUILD ACROSS THE AREA AND REMAIN IN PLACE

THROUGH THE MIDDLE OF NEXT WEEK. THIS WILL KEEP CONDITIONS HOT AND

DRY...WITH HUMIDITY VALUES DROPPING INTO THE SINGLE DIGITS EACH

AFTERNOON FOLLOWED BY GENERALLY POOR OVERNIGHT RECOVERY.

OVERALL...WINDS WILL BE LIGHT IN THE EARLY MORNING HOURS...WITH

UPSLOPE FLOW BECOMING GUSTY EACH AFTERNOON TO AROUND 25 MPH DUE TO

STRONG SURFACE HEATING. AFTERNOON WEST WINDS WILL BE STRONGEST

MONDAY AS A N AREA OF LOW PRESSURE AND JET STREAM ENERGY PASSES

THROUGH THE GREAT BASIN AND CENTRAL ROCKIES.

### &&

.PSR WATCHES/WARNINGS/ADVISORIES...

AZ...NONE.

CA...NONE.

&&

$$

NATIONAL WEATHER SERVICE PHOENIX IS ON THE INTERNET AT

WEATHER.GOV/PHOENIX

DISCUSSION...MO

AVIATION...VASQUEZ

FIRE WEATHER...MEYERS/MO

212

FXUS65 KPSR 161701

AFDPSR

AREA FORECAST DISCUSSION

NATIONAL WEATHER SERVICE PHOENIX AZ

1000 AM MST SAT JUN 16 2012

.SYNOPSIS...

PRIMARILY HOT AND DRY WEATHER WILL CONTINUE ACROSS MUCH OF TH E

REGION THROUGH AT LEAST THE MIDDLE OF NEXT WEEK. A FEW THUNDERSTORMS

WILL BE POSSIBLE LATE THIS AFTERNOON AND EVENING ACROSS FAR

SOUTHEAST ARIZONA...HOWEVER A LACK OF MOISTURE MAY LIMIT ANY FURTHER

MOVEMENT TO THE NORTH AND WEST. TEMPERATURES WILL BE GIN CLIMBING

AGAIN TODAY...REACHING NEAR OR ABOVE 110 DEGREES ON SUNDAY AND

MONDAY FOR LOW DESERT LOCATIONS. THE ABNORMALLY HOT WEATHER WILL

CONTINUE THROUGH MOST OF NEXT WEEK.

&&

.DISCUSSION...

WATER VAPOR IMAGERY SHOWS THE UPPER LOW CENTERED JUST WEST OF

NORTHERN BAJA WITH A VORT LOBE MOVING ACROSS NORTHERN BAJA AND THE

NORTHERN SEA OF CORTEZ INTO FAR SOUTHWEST ARIZONA. TO THE EAST IS

UPPER HIGH/ANTICYCLONE CENTERED OVER TEXAS WITH SOUTHERLY FLOW OVER

MUCH OF ARIZONA AND NEW MEXICO. PRECIPITABLE WATER HAS INCREASED

OVER MUCH OF SOUTHERN ARIZONA AND CUMULUS HAS ALREADY DEVELOPED IN

THIS AREA. OBSERVED AND MODEL FORECAST SOUNDINGS INDICATE THAT CAPE

OVER OUR FORECAST AREA WILL BE QUITE MODES T AND LIMITED TO OUR

EASTERN AREAS. SOUTHEAST ARIZONA SHOULD BE MORE ACTIVE BUT THOSE

STORMS WILL STRUGGLE TO PRODUCE MEANINGFUL PRECIP BUT WILL HAVE THE

POTENTIAL TO PRODUCE STRONG WINDS. WILL EXPAND THE SLIGHT CHANCE OF

THUNDERSTORMS FOR TODAY TO COV ER A LITTLE BIT MORE OF ZONE 24 AND

WILL ADD MENTION OF BLOWING DUST TO A COUPLE OF OUR SOUTH

- CENTRAL AZ

DESERT ZONES. WILL ALSO INCREASE CLOUD COVER OVERNIGHT TO REFLECT

### REMNANT DEBRIS CLOUDS. MORE LATER.

PREVIOUS DISCUSSION...

THE WELL ADVERTISED CUT OFF LOW FEATURE WILL CONTINUE TO RETROGRADE

TO THE SOUTHWEST OFF THE BAJA COAST...INTO THE PACIFIC FOR THE NEXT

SEVERAL DAYS AS STRONGER RIDGING STEADILY INTENSIFIES OVER THE

DESERT SOUTHWEST AND FOUR CORNERS REGION. IN THE INTERIM...SATELLITE

IMAGERY INDICATES A SUBTLE VORTICITY CENTER CROSSING INTO THE GULF

OF CALIFORNIA WITH BACKING SOUTHERLY FLOW IN THE H8

- H5 LAYER. WATER

VAPOR LOOPS SHOW SOME INCREASE IN ATMOSPHERIC MOISTURE CONTENT

PULLING NORTH AHEAD OF THIS VORT CENTER...THOUGH THE BEST DEEP

MOISTURE REMAINS RELEGATED TO THE CONTINENTAL DIVIDE AND POINTS

EAST. CONVECTIVE REMNANTS AND MESOSCALE OUTFLOW INITIATED LAST

EVENING IN THE EL PASO VICINITY HAS PUSHED SOMEWHAT BETTER LOW LEVEL

MOISTURE WESTWARD THROUGH FAR SOUTHWEST NEW MEXICO WHERE DEWPOINTS

HAVE INCREASED INTO THE MIDDLE/UPPER 40S...THOUGH JUST ENTERING FAR

SOUTHEAST ARIZONA WHERE KDUG REMAINS WITH LOWER 30 DEWPOINTS.

BOTH OPERATIONAL AND HIGH RESOLUTION DIRECT CONVECTIVE ALLOWING

MODELS HAVE VARYING SOLUTIONS REGARDING CONVEC TIVE EVOLUTION THIS

AFTERNOON AND EVENING. GIVEN THE SYNOPTIC ENVIRONMENT WITH DEEP

SOUTHERLY FLOW...CONCEPTUALLY WOULD EXPECT ELEVATED HIGH TERRAIN

CONVECTION TO BLOSSOM ACROSS SOUTHEAST ARIZONA THIS AFTERNOON...AND

HAVE DISCOUNTED MODELS WITH LACK OF CONVECTIVE RESPONSE (I.E. LOCAL

6KM NMM CORE). AT THE OTHER END OF THE SPECTRUM...A DRIER WESTERLY

FETCH IN THE LOW TERRAIN REGIONS OF CENTRAL ARIZONA SHOULD LIMIT THE

EXTENT OF ORGANIZED CONVECTIVE PROPAGATION TO THE NORTHWEST...AND

HAVE ELIMINATED M ODELS SHOWING PRECIPITATION IN THIS AREA (I.E. GFS

CORES). HAVE MOSTLY UTILIZED SREF PROBABILISTIC OUTPUT ALONG WITH

THE OPERATIONAL NAM AND THE NCEP 4KM WRF

- NMM HIGH RESOLUTION MODEL

TARGETING FAR SOUTHEAST ARIZONA THROUGH WEST CENTRAL NEW MEXICO WITH

THE STRONGEST SIGNALS FOR PERSISTENT CONVECTION.

THESE AREAS JUST OUTSIDE THE SOUTHERN AND EASTERN PERIPHERY OF THE

FORECAST AREA SHOULD BE CHARACTERIZED BY MUCAPES EXCEEDING 500

J/KG...DEEPLY MIXED BOUNDARY LAYERS WITH MIXING RATIOS NEAR 6

G/KG...AN D CLASSIC INVERTED

- V SOUNDINGS WITH CLOUD BASES AROUND

600MB. SREF PROBABILITIES FOR CONVECTIVE 0.01 PRECIP TOTALS

JUXTAPOSED WITH MIDLEVEL UVV AND THUNDERSTORM GUIDANCE ARE

UNQUESTIONABLY HIGH...YIELDING BETTER CONFIDENCE IN THESE AREAS FOR

AT LEAST SOME ORGANIZED THUNDERSTORMS. MEAN FLOW VECTORS FROM THE

S/SW IN THE MAJORITY OF THE CLOUD BEARING LAYER SHOULD ALLOW

ELEVATED CONVECTIVE ELEMENTS TO PROPAGATE TOWARDS GILA

COUNTY...THOUGH ECHOES MAY REMAIN PRIMARILY VIRGA...AND HAVE KEPT

JUST A MEAGER MENTION OF POPS AT THE HIGHEST ELEVATIONS. GIVEN THE

HIGH CLOUD BASES AND LARGE DCAPE VALUES ON THE WESTERN EDGE OF THE

THETA

- E GRADIENT...STILL CANNOT RULE OUT THAT OUTFLOW GENERATION

COULD STIR UP BLOWING DUST INTO PINAL AND NORTHEAST MARICO PA

COUNTIES. HOWEVER...CONFIDENCE IN THIS SCENARIO IS STILL TOO LOW TO

INTRODUCE INTO THE GRIDDED DATABASE.

BY SUNDAY...THE INFLUENCE OF THE CUTOFF SYSTEM WILL LARGELY HAVE

DRIFTED WESTWARD...WITH MUCH STRONGER SUBSIDENCE ALOFT AND A

PREVAILING WESTE RLY FETCH SHUNTING ANY DIURNAL CONVECTION WELL TO

THE EAST. H5 HEIGHTS WILL RAPIDLY INCREASE AOA 588DM WITH H7

TEMPERATURES IN A +12C TO +15C RANGE...YIELDING HIGHS MUCH ABOVE

AVERAGE. HAVE KEPT THE FORECAST FOR LOWER ELEVATIONS IN A 105F

- 115F

### RANGE... WITH THE MAJOR METROPOLITAN AREAS STILL JUST SHORT OF

EXCESSIVE HEAT CRITERIA. NEVERTHELESS...THE PERSISTENCE AND

MAGNITUDE OF THE HEAT SHOULD NOT BE TAKEN LIGHTLY...AND WILL

MAINTAIN MENTIONS IN THE HAZARDOUS WEATHER OUTLOOK AND WEBPAGE.

HEIGHTS AND T EMPERATURES ALOFT WILL BE DAMPENED SLIGHTLY ON TUESDAY

AS A WAVE PASSES THROUGH THE NRN/CNTRL ROCKIES...HOWEVER THIS WILL

ONLY BE A TEMPORARY REPRIEVE...AS STRONG RIDGING BUILDS RAPIDLY OVER

THE FOUR CORNERS REGION WITH H5 HEIGHTS EXCEEDING 590DM BY

WE DNESDAY. HAVE STAYED SOMEWHAT CONSERVATIVE FORECASTING HIGHS

EITHER SIDE OF 110F FOR THE LAST SEVERAL DAYS OF THE WEEK...AGAIN

STILL JUST SHORT OF EXCESSIVE HEAT CRITERIA. IF THE RIDGE CENTER

BECOME SITUATED CLOSER TO THE FORECAST AREA AND COMPRESSIONAL

EFFECTS MORE PRONOUNCED...THEN THE FORECAST HIGHS MAY NEED TO BE

INCREASED CLOSER TO WARNING THRESHOLDS.

&&

.AVIATION...

SOUTH

- CENTRAL ARIZONA...INCLUDING KPHX...KIWA...AND KSDL...AND

SOUTH EAST CALIFORNIA AND SOUTHWEST ARIZONA INCLUDING KIPL AND KBLH...

MOSTLY CLEAR SKIES AND LIGHT DIURNAL WINDS EXPECTED ACROSS THE

REGION AT ALL THE PHOENIX TERMINALS. MORNING SURFACE WINDS AT KPHX

WILL BE LIGHT AND VARIABLE...WITH A MORE PROMINENT EASTERL Y FLOW

ALOFT. LATEST READINGS FROM TPHX VAD WIND SHOW 10 TO 15 KTS OUT OF

THE EAST ABOVE 3KFT. WEST

- SOUTHWEST WINDS WILL GRADUALLY DEVELOP

DURING THE AFTERNOON...LINGERING UNTIL AFTER SUNSET.

SOUTHEAST CALIFORNIA AND SOUTHWEST ARIZONA INCLUDING KIPL A ND KBLH...

ALONG THE LOWER COLORADO RIVER VALLEY...CONTINUED CLEAR SKIES AND

SOME BRIEF GUSTY WINDS CAN BE EXPECTED AS THE WEAK UPPER LEVEL LOW

MOVES WEST. NOT ENOUGH CONFIDENCE AT THIS TIME TO INCLUDE IN THE

TAFS AS GUSTINESS SHOULD BE BRIEF. WINDS EX PECTED FROM THE

EAST

- SOUTHEAST THROUGH MUCH OF THE MORNING...BEFORE BECOMING MORE

DIURNAL IN DIRECTION IN THE EARLY EVENING.

AVIATION DISCUSSION NOT UPDATED FOR AMENDED TAFS.

&&

.FIRE WEATHER...

MONDAY THROUGH FRIDAY...

A STRONG UPPER RIDGE WILL BUILD ACROSS THE AREA AND REMAIN IN PLACE

THROUGH THE MIDDLE OF NEXT WEEK. THIS WILL KEEP CONDITIONS HOT AND

DRY...WITH HUMIDITY VALUES DROPPING INTO THE SINGLE DIGITS EACH

AFTERNOON FOLLOWED BY GENERALLY POOR OVERNIGHT RECOVER Y.

OVERALL...WINDS WILL BE LIGHT IN THE EARLY MORNING HOURS...WITH

UPSLOPE FLOW BECOMING GUSTY EACH AFTERNOON TO AROUND 25 MPH DUE TO

STRONG SURFACE HEATING. AFTERNOON WEST WINDS WILL BE STRONGEST

TUESDAY AS AN AREA OF LOW PRESSURE AND JET STREAM ENERG Y PASSES

THROUGH THE GREAT BASIN AND CENTRAL ROCKIES.

&&

.PSR WATCHES/WARNINGS/ADVISORIES...

### AZ...NONE.

CA...NONE.

&&

$$

NATIONAL WEATHER SERVICE PHOENIX IS ON THE INTERNET AT

WEATHER.GOV/PHOENIX

DISCUSSION...AJ/MO

AVIATION...NOLTE/CDEWEY

FIRE WEATHER...MEYERS/MO

267

FXUS65 KPSR 162218

AFDPSR

AREA FORECAST DISCUSSION

NATIONAL WEATHER SERVICE PHOENIX AZ

315 PM MST SAT JUN 16 2012

.SYNOPSIS...

PRIMARILY HOT AND DRY WEATHER WILL CONTINUE ACROSS MUCH OF THE

REGION THROUGH NEXT WEEK. AREAS O F BLOWING DUST WILL BE POSSIBLE

LATE THIS AFTERNOON AND EARLY EVENING OVER THE SOUTH

- CENTRAL ARIZONA

DESERTS. THERE IS A SLIGHT CHANCE OF THUNDERSTORMS OVER SOUTHERN

GILA COUNTY TONIGHT WITH MORE NUMEROUS STORMS OVER SOUTHEAST

ARIZONA. HOWEVER...A LACK OF MOISTURE WILL LIMIT REDEVELOPMENT OVER

THE CENTRAL DESERTS. HIGH TEMPERATURES WILL JUMP SEVERAL DEGREES

SUNDAY WITH SOME SLIGHT ADDITIONAL WARMING MONDAY...REACHING 110

DEGREES...OR SLIGHTLY MORE...FOR LOW DESERT LOCATIONS. THE ABOVE

NORMAL TEMPERA TURES WILL CONTINUE THROUGH MOST OF NEXT WEEK.

&&

.DISCUSSION...

REST OF TODAY THROUGH TUESDAY...SCATTERED THUNDERSTORMS HAVE

DEVELOPED OVER THE SOUTHEAST QUARTER OF ARIZONA EARLY THIS

AFTERNOON...ISOLATED OVER FAR EAST

- CENTRAL ARIZONA. AREAS OF BLOWING

DUST WERE ADDED TO PORTIONS OF THE SOUTH

- CENTRAL ARIZONA DESERTS FOR

EARLY THIS EVENING IN ANTICIPATION OF DISTANT THUNDERSTORMS SENDING

OUTFLOW TOWARD US AND PICKING UP DUST ALONG THE WAY. GIVEN THE EARLY

STORM DEVELOPMENT...WILL START DUST POSSIBILITIES A LITTLE EARLIER.

DOESNT LOOK LIKE THERE IS ENOUGH CAPE TO GENERATE STORMS OVER OUR

LOWER DESERTS BUT A SLIGHT CHANCE REMAINS FOR SOUTHERN GILA

COUNTY/ZONE 24. LATEST MODELS ARE SH OWING AN INCREASE IN

PRECIPITABLE WATER SPREADING ALL THE WAY INTO SOUTHEAST CALIFORNIA

TONIGHT AND LINGERING SUNDAY. HOWEVER...WARMING ALOFT WILL MAKE FOR

EVEN LESS CAPE. THUS HELD OFF ON INTRODUCING ANY POPS FOR OUR AREA

SUNDAY. THERE WILL ALSO BE WA RMING IN THE LOWER LEVELS BY SEVERAL

DEGREES AS THE UPPER LOW DRIFTS AWAY AND HIGH PRESSURE STRENGTHENS.

ANTICIPATE TEMPS TO REMAIN BELOW EXCESSIVE HEAT WARNING THRESHOLDS.

### ANTICIPATE LITTLE CHANGE IN TEMPS BUT WITH LESS PRECIPTITABLE WATER

AS THE RIDG E STARTS TO WEAKEN DUE TO A SYSTEM PASSING TO THE NORTH.

HOWEVER...TEMPS WILL BE JUST A LITTLE WARMER...CLOSE TO EXCESSIVE

HEAT THRESHOLDS. AFTERNOON AND EVENING BREEZINESS WILL BE STRONGER.

ON TUESDAY...THE LOWER LEVELS WILL BE COOLER BY AT LEAST A FEW

DEGREES DUE TO THE WEAKENED RIDGE WITH HIGHS DROPPING BELOW 110 ON

THE LOW DESERTS.

WEDNESDAY THROUGH SATURDAY...RIDGING BEGINS TO STRENGTHEN AGAIN

WEDNESDAY AND HIGHS REBOUND BY AT LEAST A FEW DEGREES. ECMWF BUILDS

THE RIDGE MORE QUICKLY THAN THE GFS AND IS CENTERED A BIT FURTHER

NORTH. THIS LEADS TO ANOTHER DIFFERENCE IN SOLUTIONS WHEREIN THE

ECMWF BRINGS IN MORE MOISTURE FROM THE EAST TOWARD THE END OF NEXT

WEEK. TAKING A BLENDED APPROACH...THURSDAY LOOKS TO BE THE WARMEST

DAY...JUST REACHING EXCESSIVE HEAT CRITERIA. ALSO...HELD OFF

INTRODUCING ANY POPS IN THE EXTENDED BUT SHOWED A SUBTLE DECREASE IN

MAX TEMPS.

&&

.AVIATION...

SOUTH

- CENTRAL ARIZONA...INCLUDING KPHX...KIWA...AND KSDL...AND

SOUTHEAST CALIFORNIA AND SOUTHWEST ARIZONA INCLUDING KIPL AND KBLH...

MOSTLY CLEAR SKIES AND LIGHT DIURNAL WINDS EXPECTED ACROSS THE

REGION AT ALL THE PHOENIX TERMINALS. MORNING SURFACE WINDS AT KPHX

WILL BE LIGHT AND VARIABLE...WITH A MORE PROMINENT EA STERLY FLOW

ALOFT. LATEST READINGS FROM TPHX VAD WIND SHOW 10 TO 15 KTS OUT OF

THE EAST ABOVE 3KFT. WEST

- SOUTHWEST WINDS WILL GRADUALLY DEVELOP

DURING THE AFTERNOON...LINGERING UNTIL AFTER SUNSET.

SOUTHEAST CALIFORNIA AND SOUTHWEST ARIZONA INCLUDING K IPL AND KBLH...

ALONG THE LOWER COLORADO RIVER VALLEY...CONTINUED CLEAR SKIES AND

SOME BRIEF GUSTY WINDS CAN BE EXPECTED AS THE WEAK UPPER LEVEL LOW

MOVES WEST. NOT ENOUGH CONFIDENCE AT THIS TIME TO INCLUDE IN THE

TAFS AS GUSTINESS SHOULD BE BRIEF. WIN DS EXPECTED FROM THE

EAST

- SOUTHEAST THROUGH MUCH OF THE MORNING...BEFORE BECOMING MORE

DIURNAL IN DIRECTION IN THE EARLY EVENING.

AVIATION DISCUSSION NOT UPDATED FOR AMENDED TAFS.

&&

.FIRE WEATHER...

MONDAY THROUGH FRIDAY...

A STRONG UPPER RIDGE WILL BUILD ACROSS THE AREA AND REMAIN IN PLACE

THROUGH THE MIDDLE OF NEXT WEEK. THIS WILL KEEP CONDITIONS HOT AND

DRY...WITH HUMIDITY VALUES DROPPING INTO THE SINGLE DIGITS EACH

AFTERNOON FOLLOWED BY GENERALLY POOR OVERNIGHT RECOVER Y.

OVERALL...WINDS WILL BE LIGHT IN THE EARLY MORNING HOURS...WITH

UPSLOPE FLOW BECOMING GUSTY EACH AFTERNOON TO AROUND 25 MPH DUE TO

STRONG SURFACE HEATING. AFTERNOON WEST WINDS WILL BE STRONGEST

TUESDAY AS AN AREA OF LOW PRESSURE AND JET STREAM ENERG Y PASSES

THROUGH THE GREAT BASIN AND CENTRAL ROCKIES.

&&

### .PSR WATCHES/WARNINGS/ADVISORIES...

AZ...NONE.

CA...NONE.

&&

$$

NATIONAL WEATHER SERVICE PHOENIX IS ON THE INTERNET AT

WEATHER.GOV/PHOENIX

DISCUSSION...AJ

AVIATION...NOLTE/CDEWEY

FIRE WEATHER...MEYERS/MO

130

FXUS65 KPSR 162237

AFDPSR

AREA FORECAST DISCUSSION

NATIONAL WEATHER SERVICE PHOENIX AZ

337 PM MST SAT JUN 16 2012

.UPDATE...TO AVIATION AND FIRE WEATHER DISCUSSIONS...

&&

...

&&

.AVIATION...

SOUTH

- CENTRAL ARIZONA...INCLUDING KPHX...KIWA...AND KSDL...AND

SOUTHEAST CALIFORNIA AND SOUTHWEST ARIZONA INCLUDING KIPL AND KBLH...

LIGHT AND VARIABLE WINDS WILL GIVE WAY TO WEST

- SOUTHWEST WINDS FOR

THE KPHX TERMINALS...GENERALLY AFTER 17/0000. CONVECTIVE ACTIVITY TO

OUR SOUTH NEAR TU CSON EXPECTED TO GENERATE OUTFLOW BOUNDARY MOVEMENT

INTO THE PHOENIX AREA THIS EVENING MAINLY FROM THE SOUTH

- SOUTHEAST

AS WELL AS SCATTERED TO BROKEN MID TO HIGH LEVEL CLOUD DECKS THIS

EVENING. AT THIS TIME...HAVE NO MENTION OF WX IN THE TAFS...BUT

CAN NOT RULE OUT SOME BLOWING DUST DECREASING VISIBILITIES FOR A

SHORT PERIOD THIS EVENING.

SOUTHEAST CALIFORNIA AND SOUTHWEST ARIZONA INCLUDING KIPL AND KBLH...

ALONG THE LOWER COLORADO RIVER VALLEY...CONTINUED CLEAR SKIES AND

SOME BRIEF GUSTY WINDS CAN BE EXPECTED AS THE WEAK UPPER LEVEL LOW

MOVES WEST. PERIODIC GUSTS UP TO 15 KTS POSSIBLE...BUT OTHER WISE

WINDS WILL STAY UNDER 10 KTS. EAST

- SOUTHEAST WINDS TO CONTINUE

THROUGH THE EARLY EVENING...BEFORE BECOMING MORE DIURNAL IN

DIRECTION IN THE EARLY EVENING AND VERY LIGHT NEAR SUNRISE.

AVIATION DISCUSSION NOT UPDATED FOR AMENDED TAFS.

### &&

...

854

FXUS65 KPSR 170345

AFDPSR

AREA FORECAST DISCUSSION

NATIONAL WEATHER SERVICE PHOENIX AZ

840 PM MST SAT JUN 16 2012

.SYNOPSIS...

PR IMARILY HOT AND DRY WEATHER WILL CONTINUE ACROSS MUCH OF THE

REGION THROUGH NEXT WEEK. AREAS OF BLOWING DUST WILL BE POSSIBLE

LATE THIS AFTERNOON AND EARLY EVENING OVER THE SOUTH

- CENTRAL ARIZONA

DESERTS. THERE IS A SLIGHT CHANCE OF THUNDERSTORMS OVER SO UTHERN

GILA COUNTY TONIGHT WITH MORE NUMEROUS STORMS OVER SOUTHEAST

ARIZONA. HOWEVER...A LACK OF MOISTURE WILL LIMIT REDEVELOPMENT OVER

THE CENTRAL DESERTS. HIGH TEMPERATURES WILL JUMP SEVERAL DEGREES

SUNDAY WITH SOME SLIGHT ADDITIONAL WARMING MONDAY.. .REACHING 110

DEGREES...OR SLIGHTLY MORE...FOR LOW DESERT LOCATIONS. THE ABOVE

NORMAL TEMPERATURES WILL CONTINUE THROUGH MOST OF NEXT WEEK.

&&

.DISCUSSION...

SCATTERED STRONG THUNDERSTORMS THAT DEVELOPED OVER SOUTHEAST AZ

SATURDAY AFTERNOON...AND PUSHED CONVECTIVE OUTFLOW BOUNDARIES AND

DUST STORMS INTO PHOENIX...WAS A FUNCTION OF UPPER LEVEL

DYNAMICS/DIFLUENT FLOW IN SOUTHEAST AZ. THIS PROVIDED GOOD UPPER

LEVEL STORM SUPPORT...WHICH WORKED IN CONJUNCTION WITH A SURGE OF

BOUNDARY LAYER MOISTURE WHICH PUSHED INTO SOUTHEAST AZ LATE FRIDAY

NIGHT/SATURDAY MORNING FROM SOUTHERN NEW MEXICO.

03Z VAD WIND PROFILERS AT PHOENIX AND TUCSON SHOWED A DEEP FETCH OF

SOUTHEASTERLY FLOW BELOW 12 THSD FEET...WHICH WILL CONTINUE TO

ADV ECT MOISTURE NORTHWARD ACROSS SOUTH CENTRAL AZ TONIGHT.

HOWEVER...AS 300/250 MB CLOSED LOW JUST OFF THE NORTHERN BAJA COAST

MOVES WESTWARD TONIGHT...A STRONG 300/250 MB ANTI

- CYCLONE WILL SHIFT

NORTH INTO AZ SUNDAY AND ESSENTIALLY STABILIZE THE ATMOSPHER E.

THEREFORE...THERE WILL BE NO REPEAT THUNDERSTORM PERFORMANCE ON

SUNDAY IN SOUTHEAST AZ.

A 300/250 MB DEFORMATION ZONE HOWEVER DOES DEVELOP FROM LAS VEGAS TO

THE WHITE MOUNTAINS IN EAST CENTRAL AZ MONDAY...PROVIDING RENEWED

UPPER LEVEL SUPPORT FOR MOUNTAIN CONVECTION EAST OF OUR ZONE 24.

OTHERWISE...MINOR UPDATES FOR TONIGHTS FORECAST WILL REMOVE THE

MENTION OF BLOWING DUST...AND SLIGHT THUNDERSTORM THREATS IN ZONE

24. REMAINDER OF FORECASTS LOOK OK.

PREVIOUS DISCUSSION...

REST OF TODAY THROUGH TUESDAY...SCATTERED THUNDERSTORMS HAVE

DEVELOPED OVER THE SOUTHEAST QUARTER OF ARIZONA EARLY THIS

### AFTERNOON...ISOLATED OVER FAR EAST

- CENTRAL ARIZONA. AREAS OF BLOWING

DUST WERE ADDED TO PORTIONS OF THE SOUTH

- CENTRAL ARIZONA DESERTS FOR

EARLY THIS EVENING IN ANTICIPATION OF DISTANT THUNDERSTORMS SENDING

OUTFLOW TOWARD US AND PICKING UP DUST ALONG THE WAY. GIVEN THE EARLY

STORM DEVELOPMENT...WILL START DUST POSSIBILITIES A LITTLE EARLIER.

DOESNT LOOK LIKE THERE IS ENOUGH CAPE TO G ENERATE STORMS OVER OUR

LOWER DESERTS BUT A SLIGHT CHANCE REMAINS FOR SOUTHERN GILA

COUNTY/ZONE 24. LATEST MODELS ARE SHOWING AN INCREASE IN

PRECIPITABLE WATER SPREADING ALL THE WAY INTO SOUTHEAST CALIFORNIA

TONIGHT AND LINGERING SUNDAY. HOWEVER...WARM ING ALOFT WILL MAKE FOR

EVEN LESS CAPE. THUS HELD OFF ON INTRODUCING ANY POPS FOR OUR AREA

SUNDAY. THERE WILL ALSO BE WARMING IN THE LOWER LEVELS BY SEVERAL

DEGREES AS THE UPPER LOW DRIFTS AWAY AND HIGH PRESSURE STRENGTHENS.

ANTICIPATE TEMPS TO REMAIN BELOW EXCESSIVE HEAT WARNING THRESHOLDS.

ANTICIPATE LITTLE CHANGE IN TEMPS BUT WITH LESS PRECIPITABLE WATER

AS THE RIDGE STARTS TO WEAKEN DUE TO A SYSTEM PASSING TO THE NORTH.

HOWEVER...TEMPS WILL BE JUST A LITTLE WARMER...CLOSE TO EXCESSIVE

HEAT THRES HOLDS. AFTERNOON AND EVENING BREEZINESS WILL BE STRONGER.

ON TUESDAY...THE LOWER LEVELS WILL BE COOLER BY AT LEAST A FEW

DEGREES DUE TO THE WEAKENED RIDGE WITH HIGHS DROPPING BELOW 110 ON

THE LOW DESERTS.

WEDNESDAY THROUGH SATURDAY...RIDGING BEGINS T O STRENGTHEN AGAIN

WEDNESDAY AND HIGHS REBOUND BY AT LEAST A FEW DEGREES. ECMWF BUILDS

THE RIDGE MORE QUICKLY THAN THE GFS AND IS CENTERED A BIT FURTHER

NORTH. THIS LEADS TO ANOTHER DIFFERENCE IN SOLUTIONS WHEREIN THE

ECMWF BRINGS IN MORE MOISTURE FROM THE EAST TOWARD THE END OF NEXT

WEEK. TAKING A BLENDED APPROACH...THURSDAY LOOKS TO BE THE WARMEST

DAY...JUST REACHING EXCESSIVE HEAT CRITERIA. ALSO...HELD OFF

INTRODUCING ANY POPS IN THE EXTENDED BUT SHOWED A SUBTLE D ECREASE IN

MAX TEMPS.

&&

.AVIATION...

SOUTH

- CENTRAL ARIZONA...INCLUDING KPHX...KIWA...AND KSDL...

THROUGH 10Z SUN...GENERALLY BKN CLOUDS AOA 20 THSD FT. SOUTHEAST

WIND 5 TO 15 KNOTS. FROM 10Z SUN TO 23Z SUN...SCT CLOUDS NEAR 20

THSD. LIGHT WINDS.

SOUTHEAST CALIFORNIA AND SOUTHWEST ARIZONA INCLUDING KIPL AND KBLH...

THROUGH 20Z SUN...CLEAR SKIES AND LIGHT WIND UNDER 10 KNOTS.

AVIATION DISCUSSION NOT UPDATED FOR AMENDED TAFS.

&&

.FIRE WEATHER...

TUESDAY THROUGH SATURDAY...

UPPER LEVEL RIDGING W ILL RETURN TO THE DESERT SOUTHWEST AND SUPPORT

WELL ABOVE NORMAL TEMPERATURES THROUGH THE WEEK. CONDITIONS WILL

REMAIN HOT AND DRY UNDER THIS RIDGING...WITH HUMIDITY VALUES

CONTINUING TO DRY INTO THE SINGLE DIGITS. OVERALL...WINDS WILL BE

LIGHT IN THE EARLY MORNING HOURS...WITH UPSLOPE FLOW BECOMING GUSTY

EACH AFTERNOON TO AROUND 25 MPH DUE TO STRONG SURFACE HEATING.

### AFTERNOON WEST WINDS WILL BE STRONGEST TUESDAY AS AN AREA OF LOW

PRESSURE AND JET STREAM ENERGY PASSES THROUGH THE GREAT B ASIN AND

CENTRAL ROCKIES. EXTENDED MODELS INDICATE SOME ENHANCED LOW TO MID

LEVEL MOISTURE MOVING INTO THE REGION FROM THE SOUTHEAST EARLY INTO

THE WEEKEND POTENTIALLY INCREASE HUMIDITIES WHILE ALSO INCREASING

AFTERNOON/EVENING CONVECTIVE POTENTIAL.

&&

.PSR WATCHES/WARNINGS/ADVISORIES...

AZ...NONE.

CA...NONE.

&&

$$

NATIONAL WEATHER SERVICE PHOENIX IS ON THE INTERNET AT

WEATHER.GOV/PHOENIX

DISCUSSION...VASQUEZ/AJ

AVIATION...VASQUEZ

FIRE WEATHER...NOLTE

732

FPUS75 KPSR 162239

NOWPSR

SHORT TERM FORECAST

NATIONAL WEATHER SERVICE PHOENIX AZ

339 PM MST SAT JUN 16 2012

AZZ028

- 170030

-

NORTHWEST AND NORTH CENTRAL PINAL COUNTY

INCLUDING THE CITIES OF...APACHE JUNCTION...CASA GRANDE...COOLIDGE...

AND FLORENCE

339 PM MST SAT JUN 16 2012

.NOW

...

...STRONG GUSTY WINDS AND BLOWING DUST...

STRONG THUNDERSTORMS THAT DEVELOPED NEAR TUCSON HAVE GENERATED A

NORTHWESTWARD MOVING OUTFLOW BOUNDARY. A LARGE AREA OF GUSTY WINDS IN

THE 25 TO 35 MPH RANGE...WITH ISOLATED GUSTS TO 40 MPH...WILL LIKELY

SWEEP THROUGH LOCATIONS NEAR FLORENCE...COOLIDGE...AND CASA GRANDE

BETWEEN 425 AND 530 PM. THIS INCLUDES PORTIONS OF INTERSTATES 8 AND

10. AREAS OF BLOWING DUST ARE ALSO LIKELY...WITH VISIBILITIES LESS

THAN 1 MILE AT TIMES.

$$

NATIONAL WEATHER SERVICE PHOENIX IS ON THE INTERNET AT

### WEATHER.GOV/PHOENIX

240

FPUS75 KPSR 170044

NOWPSR

SHORT TERM FORECAST

NATIONAL WEATHER SERVICE PHOENIX AZ

544 PM MST SAT JUN 16 2012

AZZ028

- 170245

-

NORTHWEST AND NORTH CENTRAL PINAL COUNTY

INCLUDI NG THE CITIES OF...APACHE JUNCTION...CASA GRANDE...COOLIDGE...

AND FLORENCE

544 PM MST SAT JUN 16 2012

.NOW...

...GUSTY WINDS AND BLOWING DUST IN PHOENIX...

A LARGE AREA OF GUSTY WINDS IN THE 20 TO 30 MPH RANGE...WITH ISOLATED

GUSTS TO 40 MPH...GENERATED FROM EARLIER THUNDERSTORMS NEAR

TUCSON...WILL SWEEP THROUGH THE ENTIRE GREATER PHOENIX AREA THROUGH

7 PM. AREAS OF VISIBILITIES UNDER A MILE AT TIMES WILL ALSO ACCOMPANY

THE WIND GUSTS.

$$

NATIONAL WEATHER SERVICE PHOENIX IS ON THE INTERNET AT

WEATHER.GOV/PHOENIX

745

FLUS45 KPSR 152155

HWOPSR

HAZARDOUS WEATHER OUTLOOK

NATIONAL WEATHER SERVICE PHOENIX AZ

255 PM MST FRI JUN 15 2012

AZZ023

- 028

- 162200

-

GREATER PHOENIX AREA

- NORTHWEST AND NORTH CENTRAL PINAL COUNTY

255 PM MST FRI JUN 15 2012

THIS HAZARDOUS WEATHER OUTLOOK IS FOR SOUTH

- CENTRAL ARIZONA.

.DAY ONE...THIS AFTERNOON AND TONIGHT.

NO HAZARDOUS WEA THER IS EXPECTED AT THIS TIME.

.DAYS TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY.

THERE IS A SLIGHT CHANCE OF LATE AFTERNOON AND EVENING BLOWING DUST

SATURDAY DUE TO THE POSSIBILITY OF DISTANT THUNDERSTORMS OVER

SOUTHEAST ARIZONA. SUNDAY THROUGH THURSD AY...TEMPERATURES WILL BE

WELL ABOVE NORMAL...EXCEPT PERHAPS TUESDAY...AND WILL APPROACH

EXCESSIVE HEAT THRESHOLDS.

### .SPOTTER INFORMATION STATEMENT...

SPOTTERS SHOULD FOLLOW STANDARD REPORTING PROCEDURES.

$$

785

FLUS45 KPSR 161200

HWOPSR

HAZARDOUS WEATHER OUTLOOK

NATIONAL WEATHER SERVICE PHOENIX AZ

500 AM MST SAT JUN 16 2012

AZZ023

- 028

- 171230

-

GREATER PHOENIX AREA

- NORTHWEST AND NORTH CENTRAL PINAL COUNTY

500 AM MST SAT JUN 16 2012

THIS HAZARDOUS WEATHER OUTLOOK IS FOR SOUTH

- CENTRAL ARIZONA.

.DAY ONE...TODAY AND TONIGHT.

THERE IS A SLIGHT CHANCE FOR BLOWING DUST LATE THIS AFTERNOON AND

EVENING ACROSS NORTHERN PINAL AND SOUTHEAST MARICOPA COUNTIES DUE TO

THE POTENTIAL FOR DISTANT THUNDER STORMS OVER SOUTHEAST ARIZONA.

.DAYS TWO THROUGH SEVEN...SUNDAY THROUGH FRIDAY.

TEMPERATURES WILL BE WELL ABOVE NORMAL SUNDAY AND MONDAY...AS WELL AS

WEDNESDAY THROUGH FRIDAY. HIGHS AROUND THE PHOENIX METROPOLITAN AREA

WILL BE NEAR OR SLIGHTLY ABOVE 110 DEGREES...AND APPROACHING EXCESSIVE

HEAT WARNING THRESHOLDS.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION IS NOT EXPECTED AT THIS TIME.

$$

968

WWUS75 KPSR 162342

NPWPSR

URGENT

- WEATHER MESSAGE

NATIONAL WEATHER SERVICE PHOENIX AZ

442 PM MST SAT JUN 16 2012

AZZ028

- 170100

-

/O.NEW.KPSR.DS.W.0003.120616T2342Z

- 120617T0100Z/

NORTHWEST AND NORTH CENTRAL PINAL COUNTY

INCLUDING THE CITIES OF...APACHE JUNCTION...CASA GRANDE...

F LORENCE

### 442 PM MST SAT JUN 16 2012

...DUST STORM WARNING IN EFFECT UNTIL 6 PM MST THIS EVENING...

THE NATIONAL WEATHER SERVICE IN PHOENIX HAS ISSUED A DUST STORM

WARNING...WHICH IS IN EFFECT UNTIL 6 PM MST THIS EVENING.

* AFFECTED AREA...CASA GRANDE... COOLIDGE...FLORENCE...AND SURROUNDING

COMMUNITIES...INCLUDING INTERSTATES 8 AND 10 NEAR CASA GRANDE.

* TIMING...THROUGH 6 PM MST.

* WINDS...SOUTH WIND 25 TO 35 MPH WITH ISOLATED GUSTS TO 45 MPH.

* VISIBILITY...AREAS OF LESS THAN 1/4 MILE IN BLOWING DUST.

* IMPACTS...DANGERS TO VEHICULAR TRAVEL...ESPECIALLY ON THE

INTERSTATES 8 AND 10.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A DUST STORM WARNING IS ISSUED WHEN WINDS HAVE GENERATED LARGE

AREAS O F BLOWING DUST OR BLOWING SAND THAT HAVE SUBSTANTIALLY

REDUCED VISIBILITIES...TO 1/4 MILE OR LESS...RESULTING IN

HAZARDOUS DRIVING CONDITIONS IN SOME AREAS. BE READY FOR A SUDDEN

DROP IN VISIBILITY TO NEAR ZERO. USE EXTRA CAUTION AND SLOW DOWN

WHILE DRIVIN G...AS OBJECTS ON AND NEAR ROADWAYS WILL BE SEEN ONLY

AT CLOSE RANGE. IF YOU ENCOUNTER BLOWING DUST OR BLOWING SAND ON

THE ROADWAY OR SEE IT APPROACHING...PULL OFF THE ROAD AS FAR AS

POSSIBLE AND PUT YOUR VEHICLE IN PARK. TURN THE LIGHTS ALL THE

WAY OFF AN D KEEP YOUR FOOT OFF THE BRAKE PEDAL.

&&

$$

NATIONAL WEATHER SERVICE PHOENIX IS ON THE INTERNET AT

WEATHER.GOV/PHOENIX

432

WWUS75 KPSR 170009

NPWPSR

URGENT

- WEATHER MESSAGE

NATIONAL WEATHER SERVICE PHOENIX AZ

509 PM MST SAT JUN 16 2012

AZZ023

- 170115

-

/O.EXA.KPSR.DS.W.0003.000000T0000Z

- 120617T0100Z/

GREATER PHOENIX AREA

INCLUDING THE CITIES OF...MESA...PHOENIX

509 PM MST SAT JUN 16 2012

...DUST STORM WARNING IN EFFECT UNTIL 6 PM MST THIS EVENING...

### THE NATIONAL WEATHER SERVICE IN PHOEN IX HAS ISSUED A DUST STORM

WARNING...WHICH IS IN EFFECT UNTIL 6 PM MST THIS EVENING.

* AFFECTED AREA...SOUTHERN PORTIONS OF THE EAST VALLEY...INCLUDING

QUEEN CREEK...GILBERT AND CHANDLER.

* TIMING...THROUGH 6 PM MST.

* WINDS...SOUTH WIND 25 TO 35 MPH WITH ISOLATED GUSTS TO 45 MPH.

* VISIBILITY...AREAS OF LESS THAN 1/4 MILE IN BLOWING DUST.

* IMPACTS...DANGERS TO VEHICULAR TRAVEL...ESPECIALLY ON INTERSTATE

10 AND THE LOOP 202 SANTAN FREEWAY.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A DUST STORM WARNING IS ISSUED WHEN WINDS HAVE GENERATED LARGE

AREAS OF BLOWING DUST OR BLOWING SAND THAT HAVE SUBSTANTIALLY

REDUCED VISIBILITIES...TO 1/4 MILE OR LESS...RESULTING IN

HAZARDOUS DRIVING CONDITIONS IN SOME AREAS. BE READY FOR A SUDDEN

DROP IN VISIBILITY TO NEAR ZERO. USE EXTRA CAUTION AND SLOW DOWN

WHILE DRIVING...AS OBJECTS ON AND NEAR ROADWAYS WILL BE SEEN ONLY

AT CLOSE RANGE. IF YOU ENCOUNTER BLOWING DUST OR BLOWING SAND ON

THE ROADWAY OR SEE IT APPROACHING...PULL OFF THE ROAD AS FAR AS

POS SIBLE AND PUT YOUR VEHICLE IN PARK. TURN THE LIGHTS ALL THE

WAY OFF AND KEEP YOUR FOOT OFF THE BRAKE PEDAL.

&&

$$

AZZ028

- 170115

-

/O.CON.KPSR.DS.W.0003.000000T0000Z

- 120617T0100Z/

NORTHWEST AND NORTH CENTRAL PINAL COUNTY

INCLUDING THE CITIES OF...APACHE JUNCTION...CASA GRANDE...

FLORENCE

509 PM MST SAT JUN 16 2012

...DUST STORM WARNING REMAINS IN EFFECT UNTIL 6 PM MST THIS

EVENING...

A DUST STORM WARNING REMAINS IN EFFECT UNTIL 6 PM MST THIS

EVENING.

* AFFECTED AREA...CASA GRANDE...COOLIDGE...FLORENCE...AND

SURROUNDING COMMUNITIES...INCLUDING INTERSTATES 8 AND 10 NEAR

CASA GRANDE.

* TIMING...THROUGH 6 PM MST.

* WINDS...SOUTH WIND 25 TO 35 MPH WITH ISOLATED GUSTS TO 45 MPH.

* VISIBILITY...AREA S OF LESS THAN 1/4 MILE IN BLOWING DUST.

* IMPACTS...DANGERS TO VEHICULAR TRAVEL...ESPECIALLY ON THE

INTERSTATES 8 AND 10.

### PRECAUTIONARY/PREPAREDNESS ACTIONS...

A DUST STORM WARNING IS ISSUED WHEN WINDS HAVE GENERATED LARGE

AREAS OF BLOWING DUST OR BLOWING SAND THAT HAVE SUBSTANTIALLY

REDUCED VISIBILITIES...TO 1/4 MILE OR LESS...RESULTING IN

HAZARDOUS DRIVING CONDITIONS IN SOME AREAS. BE READY FOR A SUDDEN

DROP IN VISIBILITY TO NEAR ZERO. USE EXTRA CAUTION AND SLOW DOWN

WHILE DRIVING...AS OBJECTS ON AND NEAR ROADWAYS WILL BE SEEN ONLY

AT CLOSE RANGE. IF YOU ENCOUNTER BLOWING DUST OR BLOWING SAND ON

THE ROADWAY OR SEE IT APPROACHING...PULL OFF THE ROAD AS FAR AS

POSSIBLE AND PUT YOUR VEHICLE IN PARK. TURN THE LIGHTS ALL THE

WAY OFF AND KEEP YOUR FOOT OFF THE BRAKE PEDAL.

&&

$$

NATIONAL WEATHER SERVICE PHOENIX IS ON THE INTERNET AT

WEATHER.GOV/PHOENIX

505

WWUS75 KPSR 170054

NPWPSR

URGENT

- WEATHER MESSAGE

NATIONAL WEATHER SERVICE PHOENIX AZ

554 PM MST SAT JUN 16 2012

AZZ028

- 170200

-

/O.CAN.KPSR.DS.W.0003.000000T0000Z

- 120617T0100Z/

NORTHWEST AND NORTH CENTRAL PINAL COUNTY

INCLUDING THE CITIES OF...APACHE JUNCTION...CASA GRANDE...

FLORENCE

554 PM MST SAT JUN 16 2012

...DUST STORM WARNING IS CANCELLED...

THE NATIONAL WEATHER SERVICE IN PHOENIX HAS CANCELLED THE DUST

STORM WARNING.

VISIBILITIES HAVE IMPROVED BUT STILL REMAIN BELOW ONE AND A HALF

MILES IN SPOTS.

$$

AZZ023

- 170200

-

/O.EXT.KPSR.DS.W.0003.000000T0000Z

- 120617T0200Z/

GREATER PHOENIX AREA

INCL UDING THE CITIES OF...MESA...PHOENIX

554 PM MST SAT JUN 16 2012

...DUST STORM WARNING NOW IN EFFECT UNTIL 7 PM MST THIS

EVENING...

### THE DUST STORM WARNING IS NOW IN EFFECT UNTIL 7 PM MST THIS

EVENING.

* AFFECTED AREA...THE PHOENIX METRO AREA...INCLUDING DOWNTOWN PHOENIX

AND THE EAST VALLEY.

* TIMING...THROUGH 6 PM MST.

* WINDS...SOUTH WIND 25 TO 35 MPH WITH ISOLATED GUSTS TO 45 MPH.

* VISIBILITY...AREAS OF LESS THAN 1/4 MILE IN BLOWING DUST.

* IMPACTS...DANGERS TO VEHICULAR TRAVEL...ESPECIALLY ON VALLEY FREEWAYS.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A DUST STORM WARNING IS ISSUED WHEN WINDS HAVE GENERATED LARGE

AREAS OF BLOWING DUST OR BLOWING SAND THAT HAVE SUBSTANTIALLY

REDUCED VISIBILI TIES...TO 1/4 MILE OR LESS...RESULTING IN

HAZARDOUS DRIVING CONDITIONS IN SOME AREAS. BE READY FOR A SUDDEN

DROP IN VISIBILITY TO NEAR ZERO. USE EXTRA CAUTION AND SLOW DOWN

WHILE DRIVING...AS OBJECTS ON AND NEAR ROADWAYS WILL BE SEEN ONLY

AT CLOSE RANGE. I F YOU ENCOUNTER BLOWING DUST OR BLOWING SAND ON

THE ROADWAY OR SEE IT APPROACHING...PULL OFF THE ROAD AS FAR AS

POSSIBLE AND PUT YOUR VEHICLE IN PARK. TURN THE LIGHTS ALL THE

WAY OFF AND KEEP YOUR FOOT OFF THE BRAKE PEDAL.

&&

$$

NATIONAL WEATHER SERVICE PHOENIX IS ON THE INTERNET AT

WEATHER.GOV/PHOENIX

788

WWUS75 KPSR 170149

NPWPSR

URGENT

- WEATHER MESSAGE

NATIONAL WEATHER SERVICE PHOENIX AZ

649 PM MST SAT JUN 16 2012

AZZ023

- 170300

-

/O.EXP.KPSR.DS.W.0003.000000T0000Z

- 120617T0200Z/

GREATER PHOENIX AREA

INCLUDING THE CITIES OF...MESA...PHOENIX

649 PM MST SAT JUN 16 2012

...DUST STORM WARNING WILL EXPIRE AT 7 PM MST THIS EVENING...

THE DUST STORM WARNING WILL EXPIRE AT 7 PM MST THIS EVENING.

AREAS OF BLOWING DUST ARE STILL BEING R EPORTED ACROSS THE PHOENIX

### METRO AREA. HOWEVER...CONDITIONS HAVE IMPROVED WITH VISIBILITIES

INCREASING TO BETWEEN ONE HALF OF A MILE AND ONE MILE.

$$

NATIONAL WEATHER SERVICE PHOENIX IS ON THE INTERNET AT

WEATHER.GOV/PHOENIX

749

WWUS85 KPSR 162324

SPSPSR

SPECIAL WEATHER STATEMENT

NATIONAL WEATHER SERVICE PHOENIX AZ

424 PM MST SAT JUN 16 2012

AZZ028

- 170015

-

PINAL AZ

424 PM MST SAT JUN 16 2012

...SIGNIFICANT WEATHER ADVISORY...

THE NATIONAL WEATHER SERVICE IN PHOENIX HAS ISSUED A

SIGNIFICANT WEA THER ADVISORY FOR...

CENTRAL PINAL COUNTY IN SOUTH CENTRAL ARIZONA

UNTIL 515 PM MST

AT 413 PM MST...A LARGE AREA OF GUSTY WINDS IN THE 25 TO 35 MPH

RANGE WITH ISOLATED GUSTS TO NEAR 45 MPH...GENERATED FROM STRONG

THUNDERSTORMS NEAR TUCSON...WAS MOVIN G NORTH TOWARD THE CITIES OF

FLORENCE...COOLIDGE...AND CASA GRANDE. THE AREA OF GUSTY WINDS WILL

MOVE THROUGH THE REGION BETWEEN 430 AND 530 PM. AREAS OF BLOWING

DUSTS WITH VISIBILITIES UNDER 1 MILE WILL ALSO ACCOMPANY THE WIND

GUSTS. LOW VISIBILITIES IN BLOWING DUST COULD BE DANGEROUS TO

VEHICULAR TRAVEL...ESPECIALLY ALONG PORTIONS OF INTERSTATES 8 AND 10

NEAR CASA GRANDE.

SOME UNSECURED OBJECTS COULD BE BLOWN AROUND. SEEK SHELTER INDOORS

UNTIL THE WIND STORM PASSES.

LOCALLY DENSE BLOWING DUST IS POSSIBLE. IF YOU ENCOUNTER BLOWING DUST

WHILE DRIVING...PULL OVER AS FAR OFF THE ROADWAY AS POSSIBLE AND

PARK. TURN OFF YOUR HEADLIGHTS AND KEEP YOUR FOOT OFF THE BRAKE.

LAT...LON 3275 11175 3276 11178 3279 11179 3279 11186

3305 11200 3315 11156 3330 11132 3304 11123

3273 11166 3272 11173

TIME...MOT...LOC 2318Z 160DEG 10KT 3290 11148

$$

HV

### 876

WWUS85 KPSR 162350

SPSPSR

SPECIAL WEATHER STATEMENT

NATIONAL WEATHER SERVICE PHOENIX AZ

450 PM MST SAT JUN 16 20 12

AZZ023

- 024

- 028

- 170100

-

PINAL AZ

- MARICOPA AZ

450 PM MST SAT JUN 16 2012

...SIGNIFICANT WEATHER ADVISORY...

THE NATIONAL WEATHER SERVICE IN PHOENIX HAS ISSUED A

SIGNIFICANT WEATHER ADVISORY FOR...

CENTRAL MARICOPA COUNTY IN SOUTH CENTRAL ARIZONA

NORTH CENTRAL PINAL COUNTY IN SOUTH CENTRAL ARIZONA

UNTIL 600 PM MST

AT 446 PM MST...A LARGE AREA OF GUSTY WINDS...GENERATED FROM EARLIER

THUNDERSTORMS NEAR TUCSON...WILL SWEEP THROUGH THE PHOENIX EAST

VALLEY BETWEEN 515 PM AND 630 PM. SOUTH WINDS IN THE 25 TO 35 MPH

RANGE...WITH AREAS OF VISIBILITIES LESS THAN 2 MILES IN BLOWING

DUST...WILL MOVE THROUGH THE EAST VALLEY COMMUNITIES OF QUEEN

CREEK...APACHE JUNCTION...CHANDLER...GILBERT...MESA...AND TEMPE.

A FEW ISOLATED WIND GUSTS UP TO 40 MPH ARE EXPECTED.

LOCALLY DENSE BLOWING DUST IS POSSIBLE AND MAY HAMPER VEHICULAR

TRAVEL...ESPECIALLY ALONG INTERSTATE 10. IF YOU ENCOUNTER BLOWING

DUST WHILE DRIVING...PULL OVER AS FAR OFF THE ROADWAY AS POSSIBLE

AND PARK. TURN OFF YOUR HEADLIGHTS AND KEEP YOU R FOOT OFF THE BRAKE.

LAT...LON 3342 11201 3350 11156 3326 11141 3318 11161

3316 11208

TIME...MOT...LOC 2346Z 168DEG 10KT 3325 11167

$$

HV

692

WWUS85 KPSR 170048

AWWPHX

AZZ023

- 170700

-

AIRPORT WEATHER WARNING FOR SKY HARBOR AIRPORT

NATIONAL WEATHER SERVICE PHOENIX AZ

548 PM MST SAT JUN 16 2012

...AIRPORT WEATHER WARNING FOR SKY HARBOR AIRPORT IN EFFECT UNTIL

745 PM MST...

### THE NATIONAL WEATHER SERVICE IN PHOENIX HAS ISSUED AN AIRPORT WEATHER

WARNING FOR SKY HARBOR AIRPORT FOR BLOWIN G DUST.

A DUST STORM WARNING HAS BEEN ISSUED FOR THE GREATER PHOENIX AREA...

INCLUDING SKY HARBOR INTERNATIONAL AIRPORT.

STRONG GUSTY WINDS UP TO 35 KT HAVE CREATED AREAS OF DENSE BLOWING

DUST THAT HAVE THE POTENTIAL TO RAPIDLY LOWER VISIBILITY TO LESS T HAN

1/4 MILE AT TIMES. THE DUST WILL AFFECT THE AIRPORT THROUGH AT LEAST 745

PM.

$$

## APPENDIX E

ADDITIONAL NATIONAL WEATHER SERVICE METEOROLOGICAL

DATA TABLES FOR PHOENIX

- AREA AIRPORTSElevation: 1243 ft. above sea level

Latitude: 33.268

Longitude:

- 111.812

Data Version: VER2



### Dynamically generated Tue Oct 02 14:40:02 EDT 2012 via http://cdo.ncdc.noaa.gov/qclcd/QCLCDEleva tion: 1066 ft. above sea level

Latitude: 33.527

Longitude:

- 112.295

Data Version: VER2



### Dynamically generated Tue Oct 02 14:43:22 ED T 2012 via http://cdo.ncdc.noaa.gov/qclcd/QCLCDElevation: 968 ft. above sea level

Latitude: 33.416

Longitude:

- 112.383

Data Version: VER2



### Dynamically generated Tue Oct 02 16:08:23 EDT 2012 via http://cdo.ncdc.noaa.gov/qclcd/QCLCDElevation: 1085 ft. above sea level

Latitude: 33.55

Longitude:

- 112.366

Data Version: VER2



### Dynamically generated Tue Oct 02 16:06:13 EDT 2012 via http://cdo.ncdc.noaa.gov/qclcd/QCLCDElevation: 1380 ft. above sea level

Latitude: 33.466

Longitude:

- 11 1.733

Data Version: VER2



### Dynamically generated Tue Oct 02 16:10:30 EDT 2012 via http://cdo.ncdc.noaa.gov/qclcd/QCLCDElevation: 1473 ft. above sea level

Latitude: 33.622

Longitude:

- 111.910

Data Version: VER2



### Dynamically generated Tue Oct 02 16:47:02 EDT 2012 via http://cdo.ncdc.noaa.gov/qclcd/QCLCD