State of Arizona 

Exceptional Event Documentation 

for the Event of November 4, 2011, 

for the Phoenix PM10 Nonattainment Area 

Final Report Prepared for 

Arizona Department of Environmental Quality 

Phoenix, AZ 

January 23, 2013
This PDF document contains blank pages to accommodate two-sided printing. 
Cover image depicts suspended dust and haze in the Phoenix area at 1535 LST on November 4, 2011, resulting from 

strong winds generated from an approaching cold front. This photo was taken by an ADEQ visibility camera from 

North Mountain looking south toward downtown Phoenix.

State of Arizona 

Exceptional Event Documentation 

for the Event of November 4, 2011, 

for the Phoenix PM10 Nonattainment Area 

Final Report 

STI-912092-5547-FR 

Prepared by 

Daniel Alrick 

Angela Ekstrand 

Briana Gordon 

Hilary Hafner 

Clinton MacDonald 

Hilary Minor 

Ashley Russell 

Sonoma Technology, Inc. 

1455 N. McDowell Blvd., Suite D 

Petaluma, CA 94954-6503 

Ph 707.665.9900 | F 707.665.9800 

sonomatech.com 

Prepared for 

Theresa Rigney 

Air Quality Assessment Section Manager 

1110 W. Washington Street 

Phoenix, AZ 85007 

602.771.2274

January 23, 2013 

Exceptional Event, Phoenix, November 4, 2011 Acknowledgments 

iii

Acknowledgments 

The authors would like to acknowledge the Arizona Department of Environmental Quality 

for helpful discussion and feedback during the preparation of this document. 

Exceptional Event, Phoenix, November 4, 2011 Table of Contents 

v

Table of Contents 

Section Page

List of Figures ............................................................................................................................. vii

List of Tables.................................................................................Error! Bookmark not defined.

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

1.1 Report Contents .........................................................................................................1

1.2 Exceptional Event Rule Requirements.......................................................................1

1.2.1 Public Notification that the Event Was Occurring (40 CFR 

50.14(c)(1)(i)) .................................................................................................2

1.2.2 Place Informal Flag on Data in AQS (40 CFR 50.14(c)(2)(ii))........................2

1.2.3 Notify EPA of Intent to Flag Through Submission of Initial Event 

Description by July 1 of Calendar Year Following Event (40 CFR 

50.14(c)(2)(iii))................................................................................................2

1.2.4 Document that the Public Comment Process Was Followed for Event 

Documentation (40 CFR 50.14(c)(3)(iv))........................................................2

1.2.5 Submit Demonstration Supporting Exceptional Event Flag (40 CFR 

50.14(a)(1-2)).................................................................................................3

1.2.6 Documentation Requirements (40 CFR 50.14(c)(3)(iii)) ................................3

2. Conceptual Model................................................................................................................1

2.1 Geographic Setting and Monitor Locations ................................................................1

2.2 Climate.......................................................................................................................3

2.3 Event Day Summary ..................................................................................................3

3. Causal Relationship.............................................................................................................1

3.1 Discussion..................................................................................................................1

3.2 Summary....................................................................................................................5

4. Historical Norm ....................................................................................................................1

4.1 Analysis......................................................................................................................1

4.2 Summary....................................................................................................................1

5. Not Reasonably Controllable or Preventable ......................................................................1

5.1 Background................................................................................................................1

5.1.1 Control Measures...........................................................................................1

5.1.2 Additional Measures.......................................................................................3

5.1.3 PM10 Rule Effectiveness ................................................................................4

5.1.4 Compliance and Enforcement Activities.........................................................5

5.1.5 Review of Source-Permitted Inspections and Public Complaints ..................6

5.2 Forecasts and Warnings ............................................................................................8

5.3 Wind Observations.....................................................................................................8

5.4 Summary....................................................................................................................8

6. But-For Analysis ..................................................................................................................1

6.1 Discussion..................................................................................................................1

6.2 Summary....................................................................................................................1
Exceptional Event, Phoenix, November 4, 2011 Table of Contents 

vi

Section Page

7. Conclusions .........................................................................................................................1

7.1 Affects Air Quality.......................................................................................................1

7.2 Not Reasonably Controllable or Preventable .............................................................1

7.3 Natural Event .............................................................................................................1

7.4 Clear Causal Relationship..........................................................................................2

7.5 Historical Norm...........................................................................................................2

7.6 Not Reasonably Preventable .....................................Error! Bookmark not defined.

7.7 But For .......................................................................................................................2

Video Links ..........................................................................................................................1

Appendix A...........................................................................................................A-1 

Appendix B...........................................................................................................B-1 

Appendix C...........................................................................................................C-1 

Appendix D...........................................................................................................D-1 

Appendix E...........................................................................................................E-1 
Exceptional Event, Phoenix, November 4, 2011 List of Figures 

vii

List of Figures 

Figure Page

2-1. Locations of air quality monitors that recorded exceedances of the 24-hr PM

NAAQS and the NWS monitor at Phoenix Sky Harbor International Airport (KPHX)........ 1

10

2-2. Location of sites monitoring PM10 on November 4, 2011.................................................. 1

2-3. Drainage System of Phoenix, Arizona. ............................................................................. 2

2-4. Average monthly temperatures and precipitation for Phoenix, 1981–2010.......................3

2-5. Gusty south-southwesterly winds associated with an approaching cold front 

transported dust north-northeastward to the Phoenix area on November 4, 2011. .......... 4

3-1. Visible satellite image from 1600 LST on November 4, 2011 (GOES-West), 

depicting a strong cold front across the West Coast.........................................................1

3-2. Phoenix area air quality and meteorological monitors.......................................................2

3-3. Hourly PM concentrations and wind speeds at the Zuni Hills monitor on 

November 4 and 5, 2011................................................................................................... 4

10

3-4. Hourly PM concentrations and wind speeds at the Buckeye monitor on 

November 4 and 5, 2011................................................................................................... 4

10

3-5. Hourly PM10 concentrations at Maricopa County monitors and visibility at KPHX............ 5

4-1. 24-hr average PM10 concentrations at the Higley monitor (2007–2011)........................... 1

5-1. Timeline of Maricopa County fugitive dust rules and ordinances...................................... 5
Exceptional Event, Phoenix, November 4, 2011 List of Tables 

viii

List of Tables 

Table Page

2-1. Maricopa County area monitor information and PM measurements on November 

4, 2011. ............................................................................................................................. 4

10

3-1. Observed PM , wind speeds and wind gusts at Phoenix area monitors on 

November 4, 2011............................................................................................................. 3

10

5-1. Rules and ordinances regulating particulate matter emissions in Maricopa County......... 2

5-2. Pinal County rules regulating existing and new non-point sources in Pinal County.......... 3

5-3. Pinal County rules regulating fugitive dust in Pinal County portion of Maricopa 

County PM10 Nonattainment Area..................................................................................... 3
Exceptional Event, Phoenix, November 4, 2011 Introduction

1

1. Introduction 

On November 4, 2011, 18 air quality monitors in the Phoenix PM10 nonattainment area 

recorded 24-hr average PM10 concentrations in excess of the National Ambient Air Quality 

Standard (NAAQS) for PM10 of 150 μg/m3

. The purpose of this report is to demonstrate that 

these exceedances were due to naturally occurring windblown dust, were not reasonably 

controllable or preventable, were historically unusual, and would not have occurred “but-for” the 

windblown dust and that they therefore constitute an Exceptional Event as defined by the U.S. 

Environmental Protection Agency’s (EPA) Exceptional Events Rule (EER). 

1.1 Report Contents 

Section 2 of this assessment contains a conceptual model of the wind-blown dust event 

that transpired on November 4, 2011, providing a background narrative of the exceptional event 

and an overall explanation that the event affected air quality. Section 2 also provides evidence 

that the event was a natural event. 

Section 3 of this assessment establishes a clear causal connection between the natural 

event on November 4, 2011, and the exceedances of the 24-hr PM10 standard at the monitoring 

stations. The evidence in this section also confirms that the event in question both affected air 

quality and was the result of natural events. 

Section 4 of this assessment illustrates that the event of November 4, 2011, produced 

PM10 concentrations in excess of normal historical fluctuations. 

Section 5 of this assessment details the existing dust control measures and 

demonstrates that despite the presence and enforcement of these controls, the event of 

November 4, 2011, was not reasonably controllable or preventable. 

Section 6 of this assessment builds upon the demonstrations made in the previous 

sections, showing a clear causal connection between the natural event and the exceedances, 

and concludes that the exceedances of the 24-hr PM10 standard on November 4, 2011, would 

not have occurred “but for” the event. 

Appendix A contains time-series graphs and data tables to supplement Section 3. 

Appendix B contains links to videos, images, and media reports to supplement Section 3. 

Appendix C contains time-series graphs to supplement Section 4. Appendix D contains air 

quality forecasts issued by the Arizona Department of Environmental Quality (ADEQ) and 

weather statements and warnings issued by the National Weather Service. Appendix E

contains a copy of the affidavit of public notice concerning this assessment report. 

1.2 Exceptional Event Rule Requirements 

In addition to the technical requirements that are contained within the EER, procedural 

requirements must also be met in order for the EPA to concur with the flagged air quality 
Exceptional Event, Phoenix, November 4, 2011 Introduction

2

monitoring data. This section of the report lists the requirements of the EER and associated 

guidance and discusses how ADEQ addressed those requirements. 

1.2.1 Public Notification that the Event Was Occurring (40 CFR 50.14(c)(1)(i)) 

ADEQ issued Dust Control Action Forecasts and Air Quality Forecasts for Maricopa 

County advising citizens of the potential for high wind dust events on November 4, 2011. More 

information on ADEQ’s forecasts can be found in Section 5.2 of this report. The forecast 

products that were issued for November 4, 2011, are included in Appendix D. 

1.2.2 Place Informal Flag on Data in AQS (40 CFR 50.14(c)(2)(ii)) 

ADEQ and other operating air quality agencies in Arizona submit data into the EPA’s Air 

Quality System (AQS), the official repository of ambient air quality data. This data submittal to 

AQS includes particulate matter (PM) data from both filter-based and continuous monitors 

operated in Arizona. 

When ADEQ and/or another agency operating monitors in Arizona suspect that data 

may be influenced by an exceptional event, ADEQ and/or the other operating agency expedites 

analysis of the filters collected from the potentially-affected filter-based air 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 other operating air quality agencies have determined that a potential 

exists that a monitor’s reading(s) have been influenced by an exceptional event, a preliminary 

flag is submitted for the measurement in AQS. The data are not official until they undergo more 

thorough quality assurance and quality control, leading to certification by May 1 of the year 

following the calendar year in which the data were collected (40 CFR 58.15(a)(2)). The 

presence of the flag on the November 4, 2011, data can be confirmed in AQS. 

1.2.3 Notify EPA of Intent to Flag Through Submission of Initial Event 

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 

2011 that ADEQ intends to analyze under the Exceptional Events Rule. The PM10

exceedances that occurred on November 4, 2011, in the Phoenix PM10 nonattainment area 

were included on this list. This assessment report serves as demonstration supporting the 

flagging of these data. 

1.2.4 Document that the Public Comment Process Was Followed for Event 

Documentation (40 CFR 50.14(c)(3)(iv)) 

ADEQ posted this assessment report on the ADEQ webpage and placed a hard copy of 

the report in the ADEQ Records Management Center for public review. ADEQ opened a 30-day 

public comment period on December 3, 2012. A copy of the public notice certification, along 
Exceptional Event, Phoenix, November 4, 2011 Introduction 

3

with any comments received, will be submitted to EPA, consistent with the requirements of 40 

CFR 50.14(c)(3)(iv). See Appendix E for a copy of the affidavit of public notice. 

1.2.5 Submit Demonstration Supporting Exceptional Event Flag (40 CFR 

50.14(a)(1-2)) 

At the close of the public comment period, and after ADEQ has had the opportunity to 

consider any comments submitted on this document, ADEQ will submit this document, the 

comments received, and ADEQ’s responses to those comments to EPA Region 9 headquarters 

in San Francisco, California. The deadline for the submittal of this package is September 30, 

2014. 

1.2.6 Documentation Requirements (40 CFR 50.14(c)(3)(iii)) 

The EER states that in order to justify the exclusion of air quality monitoring data, 

evidence must be provided for the following elements: 

1. The event satisfies the criteria set forth in 40 CFR 501(j) that 

a. the event affected air quality, 

b. the event was not reasonably controllable or preventable, and 

c. the event was caused by human activity unlikely to recur in a particular 

location or was a natural event; 

2. There is a clear causal relationship between the measurement(s) under 

consideration and the event; 

3. The event is associated with a measured concentration(s) in excess of normal 

historical fluctuations; and 

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

Exceptional Event, Phoenix, November 4, 2011 Conceptual Model 

1 

2. Conceptual Model 

This section provides a narrative background and summarizes the meteorological and 

air quality conditions in place on November 4, 2011 in the Phoenix area. Elements described in 

this section include 

 A description and map of the geographic setting of the air quality and meteorological 

monitors. 

 A description of Phoenix’s climate. 

 An overall description of meteorological and air quality conditions on the event day. 

2.1 Geographic Setting and Monitor Locations 

Phoenix is located in the Salt River Valley in south-central Arizona. It lies at an elevation 

of 1,090 feet above mean sea level (msl) in the northeastern part of the Sonoran Desert. Other 

than the mountains in and around the city, the topography of Phoenix is generally 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 

White Tank Mountains (~4,500 ft msl) to the west, the Sierra Estrella (~4,450 ft msl) to the 

southwest, and the Superstition Mountains (~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. 

A fairly dense network of air quality and meteorological monitors exists throughout the 

Phoenix area, with a much less dense network of monitors throughout the rest of Arizona. 

Figure 2-1 shows the general geographic setting of Phoenix, as well as the locations of PM10

monitors that recorded exceedances on November 4, 2011. These monitors include AQS 

monitors, which measure air quality and meteorological data, and National Weather Service 

(NWS) monitors, which measure meteorological data only. Some of the AQS monitors in the 

Phoenix area are run by the Maricopa County Air Quality Department (MCAQD), while others 

are run by ADEQ. The primary NWS site used in this demonstration package was the Phoenix 

Sky Harbor International Airport (KPHX) site, because of that site’s high data quality, data 

completeness, and representativeness of meteorological conditions in the Phoenix area. 

Figure 2-2 shows the locations of PM10 monitors statewide on November 4, 2011. 

Figure 2-3 depicts the drainage systems or watersheds for the State of Arizona. Many 

of the rivers that form Arizona’s drainage system are dry for most of the year and, consequently, 

are sources of silt and fine soils that become suspended and add to regional PM10 loadings 

during high wind events. Much of this alluvial matter and fine soil is deposited in the low-lying 

areas of central and southern Arizona, with larger depositional areas focused in and around the 

confluences of dry river channels.
Exceptional Event, Phoenix, November 4, 2011 Conceptual Model

1 

Figure 2-1. Locations of air quality monitors that recorded exceedances of the 24-hr PM10 NAAQS and NWS monitors in the 

Phoenix area.
Exceptional Event, Phoenix, November 4, 2011 Conceptual Model 

1 

Figure 2-2. Location of sites monitoring PM10 in Arizona on November 4, 2011. 
Exceptional Event, Phoenix, November 4, 2011 Conceptual Model 

2 

Figure 2-3. Drainage system of Phoenix, Arizona. 
Exceptional Event, Phoenix, November 4, 2011 Conceptual Model 

3 

2.2 Climate 

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

average summer high temperatures are among the hottest of any populated area in the United 

States (Figure 2-4). Temperatures reach or exceed 100°F an average of 110 days annually, 

and reach or exceed 110°F an average of 18 days annually. Phoenix receives an average of 

7.66 inches of rain per year. The bulk of this rain usually falls during the December through 

March and July through August time periods. During the December through March period, 

winter storms originating from the Pacific Ocean can produce significant rains in southwestern 

Arizona. During the mid- to late-summer time period, monsoonal moisture originating from the 

Gulf of California, Gulf of Mexico, and large thunderstorm complexes over the Sierra Madre 

Occidental Mountains in Mexico move northward into Arizona. 

0.0

0.2

0.4

0.6

0.8

0

20

40

60

80

1.0

1.2

100

120

Precipitation (inches)

Temperature (°F)

Precipitation

Max Temp

Min Temp

Mean Temp

Figure 2-4. Average monthly temperatures and precipitation for Phoenix, 1981–2010. 

While windblown dust events in Arizona during the summer monsoon season are often 

due to outflow winds from thunderstorms, windblown dust events in the fall are usually due to 

strong winds associated with low-pressure systems and cold fronts moving southeast across 

California and Arizona. These winds are the result of strong surface pressure gradients 

between the approaching low-pressure system or cold front and higher pressure ahead of it. As 

the low-pressure system (or cold front) approaches and passes, gusty southwesterly winds 

typically shift to northwesterly. The strong winds can loft dust into the air and transport it over 

long distances, especially if soils in the source region are dry. 

2.3 Event Day Summary 

On the afternoon and evening of November 4, 2011, strong winds generated by an 

approaching cold front transported dust northeastward into the Phoenix area (Figure 2-5; cold 
Exceptional Event, Phoenix, November 4, 2011 Conceptual Model 

4 

front depicted in blue). The windblown dust resulted in 24-hr average PM10 concentrations in 

exceedance of the NAAQS at 18 air quality monitors (Table 2-1). The PM10 concentrations 

measured at these monitors were in excess of normal historical fluctuations. The dust was 

naturally occurring and likely originated over undeveloped lands south of the Phoenix area, and 

wind speeds in excess of 20 mph throughout the Phoenix area and over 25 mph at some NWS 

stations, with gusts frequently over 35 mph, overwhelmed reasonable dust control measures. 

The PM10 monitors with exceedances were located across the Phoenix PM10 nonattainment 

area, as well as in Pinal, Pima, and Santa Cruz Counties, illustrating the widespread, regional 

nature of this event. 

Phoenix

Figure 2-5. Gusty south-southwesterly winds associated with an approaching cold front 

transported dust north-northeastward to the Phoenix area on November 4, 2011. 

Table 2-1. Maricopa County area monitor information and PM10 measurements on 

November 4, 2011. The exceedance monitors discussed in this report are shown in bold. 

Monitor Monitor 

Type Operator AQS Monitor ID 

24-hr Avg 

PM10

(μg/m3) 

1-hr Max 

PM10

(μg/m3)

Time of 

Max 1-hr 

PM10

(LST) 

AQS 

Qualifier 

Flag 

Maricopa County 
Exceptional Event, Phoenix, November 4, 2011 Conceptual Model 

5 

Monitor Monitor 

Type Operator AQS Monitor ID 

24-hr Avg 

PM10

(μg/m3) 

1-hr Max 

PM10

(μg/m3)

Time of 

Max 1-hr 

PM10

(LST) 

AQS 

Qualifier 

Flag 

Buckeye TEOM MC 04-013-4011-81102-1 284 1638 1700 RJ 

Central Phoenix TEOM MC 04-013-3002-81102-4 223 1258 1800 RJ 

Durango Complex TEOM MC 04-013-9812-81102-1 251 1145 1700 RJ 

Dysart TEOM MC 04-013-4010-81102-1 224 1370 1800 RJ 

Fort McDowell/Yuma 

Frank TEOM FMIR 04-013-5100-8112-1 237 N/A N/A 

Glendale TEOM MC 04-013-2001-81102-1 229 1083 1700 RJ 

Greenwood TEOM MC 04-013-3010-81102-1 231 1507 1800 RJ 

Higley TEOM MC 04-013-4006-81102-1 258 1243 1500 RJ 

JLG Supersite BAM ADEQ 04-013-9997-81102-3 200 985 

985 

1700 

1800 RJ 

JLG Supersite TEOM ADEQ 04-013-9997-81102-4 199 1346 1800 RJ 

North Phoenix TEOM MC 04-013-1004-81102-1 186 N/A N/A RJ 

North Phoenix BAM MC 04-013-1004-81102-2 186 1053 1800 RJ 

South Phoenix TEOM MC 04-013-4003-81102-1 231 904 1800 

West Chandler TEOM MC 04-013-4004-81102-1 670 2745 1500 RJ 

West 43rd Avenue TEOM MC 04-013-4009-81102-1 242 1230 1700 RJ 

West Phoenix TEOM MC 04-013-0019-81102-1 279 1506 1700 RJ 

Zuni Hills TEOM MC 04-013-4016-81102-1 258 1574 1800 RJ 

Apache County 

N/A N/A WMAT 04-001-1003-81102-1 29 56 2200 

Cocnino County 

N/A N/A ADEQ 04-005-1237-81102-1 N/A N/A N/A 

Gila County 

Hayden Old Jail TEOM ADEQ 04-007-1001-81102-3 119 508 2300 IJ 

Navajo County 

N/A N/A WMAT 04-017-1002-81102-1 36 63 2100 

Pima County 

Ajo TEOM ADEQ 04-019-0001-81102-3 149 444 1400 IJ 

Geronimo BAM PCDEQ 04-019-1113-81102-1 116 517 2200 

Green Valley BAM PCDEQ 04-019-1030-81102-1 62 230 2100 

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

Rillito TEOM ADEQ 04-019-0020-81102-3 226 1241 2200 RJ 

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

Pinal County 

Apache Junction 

Fire Station TEOM PCAQCD 04-021-3002-81102-3 225 825 1600 RJ 

Casa Grande 

Downtown TEOM PCAQCD 04-021-0001-81102-3 428 2377 1500 RJ 

Combs School TEOM PCAQCD 04-021-3009-81102-3 280 1132 1600 RJ 

Cowtown TEOM PCAQCD 04-021-3013-81102-3 395 1326 1500 RJ 
Exceptional Event, Phoenix, November 4, 2011 Conceptual Model 

6 

Monitor Monitor 

Type Operator AQS Monitor ID 

24-hr Avg 

PM10

(μg/m3) 

1-hr Max 

PM10

(μg/m3)

Time of 

Max 1-hr 

PM10

(LST) 

AQS 

Qualifier 

Flag 

Maricopa TEOM PCAQCD 04-021-3010-81102-3 336 1123 1600 RJ 

Pinal County Housing TEOM PCAQCD 04-021-3011-81102-3 1161 2404 1400 RJ 

Stanfield TEOM PCAQCD 04-021-3008-81102-3 586 1987 1500 RJ 

Santa Cruz County 

Nogales Post Office BAM ADEQ 04-023-0004-81102-3 151 316 1600 IJ 

Yuma County 

Yuma Supersite TEOM ADEQ 04-027-8011-81102-3 52 170 1700 

TEOM: Tapered element oscillating microbalance monitor 

BAM: Beta attenuation monitor 

FRM: Federal reference method 

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

MC: Maricopa County Air Quality Department 

ADEQ: Arizona Department of Environmental Quality 

FMIR: Fort McDowell Indian Reservation 

PCAQCD: Pinal County Air Quality Control District 

PCDEQ: Pima County Department of Environmental Quality 

RJ: qualifier flag for high winds 

IJ: qualifier flag for high winds 
Exceptional Event, Phoenix, November 4, 2011 Causal Relationship

3. Causal Relationship 

3.1 Discussion 

Meteorological and air quality observations indicate that dust carried by gusty winds 

accompanied by an approaching cold front was directly responsible for the high PM10

concentrations observed in the Phoenix area on November 4, 2011. On the afternoon of 

November 4, a strong cold front was rapidly moving southeastward across California into 

western Arizona (Figure 3-1). A strong surface pressure gradient associated with this front led 

to the development of widespread, gusty southwesterly winds across much of Arizona, including 

in the Phoenix area. The likely source region for PM10 during the November 4, 2011, event was 

the south-central Arizona desert region south of the Phoenix PM10 nonattainment area. This 

region largely consists of natural, undisturbed desert. In addition, the two-month period prior to 

November 4, 2011, was very dry in Phoenix, with only 0.08 inches of rain recorded at Phoenix 

Sky Harbor International Airport; as a result, soils were very dry. This combination of geography 

and lack of rainfall preceding the event resulted in a large fetch of soils that were particularly 

vulnerable to particulate suspension. 

Figure 3-1. Visible satellite image from 1600 LST on November 4, 2011 (GOES-West), 

depicting a strong cold front approaching Arizona. Strong south to southwesterly winds 

ahead of this front transported dust into the Phoenix area. 

1 
Exceptional Event, Phoenix, November 4, 2011 Causal Relationship

As the cold front approached Phoenix, winds from the southwest increased and were 

gusty for most of the afternoon and evening. Figure 3-2 and Table 3-1 illustrate wind and PM10

data in the Phoenix area during the late afternoon hours of November 4, 2011, when PM10

concentrations were highest. Monitors in the Phoenix area measured sustained winds of over 

20 mph and wind gusts in excess of 30 mph coincident with the high PM10 concentrations while 

some NWS stations in the Phoenix area measured sustained winds above 25 mph with strong 

gusts above 35 mph (Figures 3-3 and 3-4, Table 3-1, Appendix A). These conditions lasted 

for several hours, resulting in a prolonged period of dust transport into the Phoenix area. 

Visibility at KPHX (Figure 3-5) and other regional airports (Appendix A) also decreased 

significantly with the arrival of the dust, prompting the National Weather Service office in 

Phoenix, Arizona, to issue a Dust Storm Warning for Maricopa County (see Appendix D). It is 

also important to note that winds were lighter and PM10 concentrations were much lower before 

the dust storm, illustrating the correlation between the high winds and the dust. Visibility 

cameras in the Phoenix area also clearly depicted the rapid arrival of dust and the resulting 

significant reduction in visibility on the afternoon of November 4, 2011. Links to these videos 

and other media coverage and images pertaining to this windblown dust event are shown in 

Appendix B. 

Figure 3-2. Phoenix area air quality and meteorological monitors. Wind and PM10 data 

and time of observation are shown in Table 3-1. Gusty southwesterly winds ahead of an 

approaching cold 

front transported dust into the Phoenix area on November 4, 2011. Circular symbols and 

numbers are placed at the location of the monitor site; wind barbs are offset for visual 

clarity. 

2 
Exceptional Event, Phoenix, November 4, 2011 Causal Relationship

Table 3-1. PM10, wind speeds and wind gusts at Phoenix area monitors on November 4, 

2011. Symbols in the first column correspond to monitor locations in Figure 3-2. 

R R

Monitor 

1-hr Max 

PM10

(g/m3) 

Time of 

Observation 

(LST) 

Wind 

Speed 

(mph) 

Wind 

Gust 

(mph) 

Wind 

Direction 

(degrees) 

Higley 1243 1500 14 32 215 

West Chandler 2745 1500 19 36 218 

KIWA - 1547 17 35 220 

KGEU - 1547 21 29 220 

KPHX - 1551 20 27 190 

KCHD - 1654 28 32 210 

Buckeye 1638 1700 21 39 217 

KDVT - 1700 21 28 230 

Durango 

Complex 1145 17:00 13 29 245 

Glendale 1083 1700 20 40 233 

West 43rd

Avenue 1230 1700 16 31 242 

West Phoenix 1506 1700 16 33 246 

JLG 

Supersite(3) 985 1700 9 23 239 

KBXK - 1755 25 36 180 

KLUF - 1757 32 38 220 

Central Phoenix 1258 1800 16 33 259 

Dysart 1370 1800 14 33 212 

Greenwood 1507 1800 14 32 237 

JLG 

Supersite(4) 1346 1800 11 26 234 

North 

Phoenix(2) 1053 1800 11 30 240 

South Phoenix 904 1800 7 27 255 

Zuni Hills 1574 1800 22 37 218 

4 

13 

16 

10 

9 

7 

2 

5 

1 

14 

2 

12 

6 

4 

11 

7 

6 

2 

15 

5 

3 

8 

3 
Exceptional Event, Phoenix, November 4, 2011 Causal Relationship

Figure 3-3. Hourly PM10 concentrations and wind speeds at the Zuni Hills monitor on 

November 4 and 5, 2011. PM10 concentrations and wind speeds sharply increased at 

1600 LST on November 4, 2011, indicating the arrival of windblown dust. Note that PM10

concentrations were not available at 1200 or 1300 LST on November 4, 2011 or at 0200 

LST on November 5, 2011. 

Figure 3-4. Hourly PM10 concentrations and wind speeds at the Buckeye monitor on 

November 4 and 5, 2011. PM10 concentrations and wind speeds sharply increased at 

1600 LST on November 4, 2011, indicating the arrival of windblown dust. Sustained 

winds were measured over 20 mph with gusts over 35 mph. Note that PM10

concentration data was not available at 0000 LST on November 5, 2011. 

4 
Exceptional Event, Phoenix, November 4, 2011 Causal Relationship 

Figure 3-5. Hourly PM10 concentrations at Maricopa County monitors and visibility at 

KPHX. Visibility was greatly reduced after 1500 LST on November 4, coinciding with the 

sharp increase in PM10 concentrations at Phoenix area monitors, indicating the arrival of 

windblown dust. 

Strong, gusty winds continued into the overnight hours as the cold front moved through 

the Phoenix area. However, PM10 concentrations decreased after 2000 LST; this drop in PM10

was likely due in part to rain showers. The rain acts to remove suspended PM10 from the 

atmosphere and also moistens the surface, making the soils less vulnerable to suspension by 

the strong winds. 

3.2 Summary 

The information presented in this section demonstrates a clear causal relationship 

between the windblown dust and the PM10 exceedances measured in the Phoenix PM10

nonattainment area on November 4, 2011. The wind and PM10 data shown in this section 

illustrate the spatial and temporal representation of the dust storm as it moved through Maricopa 

County. In addition, the time series plots of air quality and meteorological data found in this 

section and in Appendix A show that the sharp increase in PM10 concentrations coincided with 

the strong wind speeds and wind gusts, and that the strong winds and high PM10 concentrations 

were experienced over a large area. 

5 
Exceptional Event, Phoenix, November 4, 2011 Historical Norm 

4. Historical Norm 

4.1 Analysis 

PM10 concentrations measured at Phoenix-area monitors on November 4, 2011, were 

unusual and in excess of normal historical fluctuations. To establish the severity of this event, 

PM10 concentrations measured on November 4, 2011, were compared to a historical 2007–

2011 5-year annual data set at each monitor (Figure 4-1 and Appendix C). The PM10

concentrations measured at the Higley monitor (Figure 4-1) on November 4, 2011, resulted in 

one of the highest 24-hr averages measured over the 5-year period. Similar time-series plots 

for the other monitors with exceedances of the 24-hour PM10 standard are shown in Appendix 

C. 

Figure 4-1. 24-hr average PM10 concentrations at the Higley monitor (2007–2011). The 

24-hr average PM10 concentration on November 4, 2011, is shown in red and highlighted 

by the arrow. 

4.2 Summary 

Given the recorded values and using a methodology similar to the one accepted by EPA, 

it is clear that the PM10 levels on November 4, 2011, were outside normal historical fluctuations. 

This analysis provides evidence that the event affected air quality on a historic scale. 
Exceptional Event, Phoenix, November 4, 2011 Historical Norm 

 
Exceptional Event, Phoenix, November 4, 2011 Not Reasonably Controllable or Preventable

1 

5. Not Reasonably Controllable or Preventable 

5.1 Background 

ADEQ and MCAQD are responsible for implementing regulatory measures to control 

emissions from agricultural sources, stationary sources, fugitive dust sources, and open burning 

within Maricopa County. Three major programs provide or contribute to air pollution control 

measures for the Greater Phoenix area. These programs include 

1. ADEQ’s Agricultural Best Management Program (AgBMP) 

2. Maricopa County’s Inspection and Compliance Program 

3. ADEQ’s Air Quality Forecasting Program 

Specifically, ADEQ is responsible for compliance assistance and enforcement of 

Agricultural Best Management Practices developed by the Governor’s Agricultural Best 

Management Practices Committee, while MCAQD is responsible for compliance assurance for 

all other significant sources of PM10 emissions. In addition to routine inspections and 

inspections driven by complaints, inspections are often increased when (1) ADEQ forecasters 

issue a Maricopa County Dust Control Forecast of “High Risk”, (2) ADEQ forecasters issue a 

High Pollution Advisory, or (3) near-real-time monitoring data indicate unique activity via high 

PM concentrations. The forecasting program and inspection/compliance programs work 

together so that resources can be best utilized during days of greatest risk for elevated PM 

emissions. 

On July 25, 2002, EPA took initial action to finalize approval of the Best Available 

Control Measure (BACM) and the Most Stringent Measure (MSM) demonstrations in the Serious 

Area PM10 plan for the Maricopa County portion of the metropolitan Phoenix PM10

nonattainment area (67 FR 48718). These BACM and MSM demonstrations were again 

approved by EPA on July 14, 2006 (71 FR 43979). The Agricultural Best Management 

Practices General Permit rule and related definitions have been adopted into the Arizona 

Administrative Code as R18-2-610 and R18-2-611, pursuant to Arizona Revised Statutes 

§49-4571

. 

5.1.1 Control Measures 

Maricopa County regulations of PM10 emissions are listed in Table 5-1. 

 

1

 Updates to the AgBMP program in December, 2011, clarified BMPs for crops and added BMPs for animal 

operations. Effective 12/29/2011, R18-2-611 was renumbered to R18-2-610.01 Agricultural PM10 General 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. 
Exceptional Event, Phoenix, November 4, 2011 Not Reasonably Controllable or Preventable

2 

Table 5-1. Rules and ordinances regulating PM emissions in Maricopa County. 

Rule/Ordinance Number & Title Description 

Rule 300: Visible emissions Establishes standards for visible emissions and opacity. 

Rule 310: Fugitive dust from dustgenerating 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 nontraditional 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 which are not regulated by Rule 310 and which are 

not required to have either 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 emissions of air pollutants from medical 

waste incinerators. 

Rule 322: Power plant operations 

Establishes limits for the emissions of nitrogen oxides, sulfur oxides, 

carbon monoxide, and particulate matter from existing power plants 

and cogeneration plants. 

Rule 323: Fuel burning equipment 

from industrial/commercial/ 

institutional (ICI) sources 

Establishes limits for the emissions of nitrogen oxides, sulfur oxides, 

carbon monoxide and particulate matter from ICI sources. 

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 engines 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 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 wood 

burning restriction Establishes restrictions for residential wood burning. 

Ordinance P-27: Vehicle parking 

and use on unstabilized vacant lots 

Establishes restrictions for vehicle parking and use on unstabilized 

vacant lots in unincorporated sections of Area A in Maricopa County. 

Ordinance P-28: Off-road vehicle 

use in unincorporated areas of 

Maricopa County 

Establishes restrictions for operating vehicles on unpaved property in 

unincorporated areas of Maricopa County. 
Exceptional Event, Phoenix, November 4, 2011 Not Reasonably Controllable or Preventable

3 

Rule/Ordinance Number & Title Description 

Arizona Administrative Code R18-

2-611 & 610: Agricultural PM10

general permit 

Establishes a requirement for commercial farmers to implement best 

management practices and maintain a record demonstrating 

compliance. 

5.1.2 Additional Measures 

In addition to the rules and regulations listed in Table 5-1, other PM10-reducing control 

measures (e.g., paving unpaved roads, PM10-certified street sweepers, controlling unpaved 

parking lots, etc.) have been committed to and implemented by local jurisdictions throughout the 

PM10 nonattainment area and incorporated into the Arizona state implementation plan (SIP) 

through PM10 plans such as the Revised Maricopa Association of Governments’ (MAG) 1999 

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

County Air Quality Control District (PCAQCD) also implements regulatory control measures on 

emissions from existing and new non-point sources within Pinal County (see Table 5-2). 

Additionally, the PCAQCD implements specific nonattainment rules for that part of the Phoenix 

PM10 nonattainment area that resides in Pinal County (see Table 5-3). 

Table 5-2. Pinal County rules regulating existing and new non-point sources in Pinal County. 

Article Number & Title Description 

Article 2: Fugitive dust Provides a mechanism to reasonably regulate operations which 

periodically may cause fugitive dust emissions into the atmosphere. 

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. 

Table 5-3. Pinal County rules regulating fugitive dust in Pinal County portion of the 

Phoenix PM10 Nonattainment Area. 

Article Number & Title Description 

Article 4: Nonattainment area rules; 

dustproofing for commercial parking, 

drives, and yards 

Establishes rules to avoid violations of the prevailing PM10 standard 

and additionally minimize nuisance impacts by improving control of 

excessive fugitive dust emissions from unpaved parking lots. 

Article 5: Nonattainment area rules; 

stabilization for residential parking 

and drives 

Establishes rules for stabilizing residential properties. 

Article 6: Restrictions on vehicle 

parking and use on vacant lots Establishes rules for unpaved or unstable vacant lots. 

Article 7: Construction sites in 

nonattainment areas – fugitive dust 

Establishes rules to avoid violations of the prevailing PM10 standard 

and additionally minimize nuisance impacts by improving control of 

excessive fugitive dust emissions from activities associated with 

construction, earthwork, or land development. 
Exceptional Event, Phoenix, November 4, 2011 Not Reasonably Controllable or Preventable

4 

Article Number & Title Description 

Article 8: Nonattainment area rules, 

requirement for stabilization of 

disturbed areas at vacant lots 

Establishes rules for stabilizing disturbed areas at vacant lots. 

5.1.3 PM10 Rule Effectiveness 

MCAQD analyzed the effectiveness of its fugitive dust rules (Rules 310, 310.01 and 316) 

in terms of permit compliance rates. This rule effectiveness (RE) study was designed to assess 

how many sources regulated by MCAQD during the subject time period received no PM10

emissions-related violations. As a basis for comparison, the percentage of permitted sources 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 strengthened, 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 Salt River Area and the Maricopa Association of Governments 2007 

Five Percent Plan for PM10 for the Maricopa County Nonattainment Area to reduce PM10

emissions throughout the county. Three major areas that contributed to increased compliance 

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

regulatory changes that broadened 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, 95% compliance (from 85%) for Rule 310.01 sources, and 65% (from 40%) 

for Rule 316 sources. These improvements continued into calendar year 2010 with compliance 

rates of 94% for Rule 310 sources, 96% for Rule 310.01 sources, and 73% for Rule 316 

sources. The timeline below (Figure 5-1) illustrates the improvements in RE over the last 

several years; it also points out significant revisions to previous rules, as well as newly adopted 

rules and ordinances. 
Exceptional Event, Phoenix, November 4, 2011 Not Reasonably Controllable or Preventable

5 

Figure 5-1. Timeline of Maricopa County fugitive dust rules and ordinances. 

5.1.4 Compliance and Enforcement Activities 

MCAQD is prepared to proactively respond to high wind events and protect human 

health and well-being. MCAQD ‘s approach consists of two primary components: proactive 

inspections conducted routinely, as well as surveillance inspections conducted during and after 

significant air quality 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 sources are also regularly inspected multiple times every year. Maricopa County responds 

to the majority of complaints within 24 hours. 

Maricopa County monitors the ADEQ Five-Day Dust Control Forecast to identify the 

potential for elevated PM10 pollution levels due to high winds or stagnant conditions. When a 

High Pollution Advisory (HPA) is issued for Maricopa County, MCAQD conducts increased 

surveillance before, during, and after the forecast event(s). MCAQD also conducts event 

surveillance and post-event activities during exceedance days that had not been forecast (i.e., 

those 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 violations for failure to 

comply with local, state, or federal regulations. During the event, MCAQD inspectors survey 

high-risk areas to confirm that control measures are in place, document any violations, and 

contact other regulatory agencies if necessary. Post-event activities include continued surveys 

of high-risk areas, re-inspecting sources that had incurred violations within two business days, 

and an internal MCAQD debriefing of event activities. 

During 2011, a total of 14 MCAQD air monitoring sites were upgraded with new 

equipment that allows the monitoring sites to automatically report measured readings at 

5-minute intervals. Previously, only hourly readings were available. The real-time data 

reporting system includes a mechanism to alert MCAQD field staff when PM concentrations are 

elevated. The system allows MCAQD responders to review concentrations at the monitors and 
Exceptional Event, Phoenix, November 4, 2011 Not Reasonably Controllable or Preventable

6 

to consult the National Weather Service website to check for weather event activity. This 

capability allows the MCAQD responder to identify regional events and monitor specific issues. 

If necessary, the MCAQD responders can inform nearby stakeholders and local governments of 

the elevated PM10 concentraitons. 

5.1.5 Review of Source-Permitted Inspections and Public Complaints 

ADEQ’s Arizona Unified Repository for Information Tracking of the Environment 

(AZURITE) database was queried to compile a list of inspections for the permitted sources in 

the Maricopa area around the time of the November 4, 2011, PM10 exceedances. An evaluation 

of all inspection reports, air quality complaints, compliance reports, and other documentation did 

not indicate any evidence of unusual anthropogenic-based PM10 emissions. During the period 

of November 1 through November 7, 2011, MCAQD inspectors conducted a total of 146 

inspections of permitted facilities, of which 91 were at fugitive dust sources. Additionally, 

MCAQD conducted 209 inspections on vacant lots and unpaved parking lots. During this 7-day 

period, a total of 18 violations were issued countywide for PM10 and non-PM10 related violations. 

Nine violations were issued for PM10 emissions within a 4-mile radius of an exceeding monitor 

(Buckeye, Central Phoenix, Higley, and Zuni Hills). 

On November 2, 2011, two violations were issued to a permitted facility within 4 miles of 

the Buckeye monitor. A violation was issued for failure to maintain records of daily selfinspection and implementation of control measures from the Dust Control Plan. A second 

violation was issued for failure to provide to the inspector, in a timely manner, operational 

records required in the permit pertaining to grain loading and unloading. The source corrected 

the violations on subsequent inspections. The permitted site is located approximately 1.8 miles 

northeast of the Buckeye monitor. During the exceptional event on November 4, 2011, winds 

were generally from the southwest at the Buckeye monitor. 

On November 3, 2011, a violation was issued to a permitted construction site for failure 

to maintain records of daily self-inspection and implementation of control measures in the Dust 

Control Plan. At the time of the inspection, no disturbed surfaces were observed, and the 

source was complying with the required control measures detailed in their earthmoving permit. 

The source corrected the violation and maintained compliance with their permit on subsequent 

inspections. The site is approximately 1.4 miles southeast of the Central Phoenix monitor. 

During the exceptional event, the winds were generally from the west and southwest at the 

Central Phoenix monitor. 

On November 4, 2011, three violations were issued to a permitted construction site 

within 4 miles of the Higley monitor. A violation was issued for approximately 0.22 acres of 

disturbed area on which no earthmoving activity was occurring. A second violation was issued 

for failure to keep dust control records. A third violation was issued for exceeding the permitted 

earthmoving area by approximately 0.11 acres. The inspector observed the stability issue at 

1210 LST and remained onsite until the entire site was stabilized with water at 1330 LST. The 

Higley monitor began showing exceedances at about 1500 LST. The site was permitted for 

0.96 acres and observed with 0.22 acres of unstable surface areas. The permitted site is 

approximately 1.0 mile north of the Higley monitor. During the exceptional event, the winds 

were generally from the south and southwest at the Higley monitor. 
Exceptional Event, Phoenix, November 4, 2011 Not Reasonably Controllable or Preventable

7 

MCAQD was prepared for any complaints received due to the high wind event. During 

the 7-day period from November 1 through November 7, 2011, MCAQD received 41 complaints, 

of which 30 were related to windblown dust. Each complaint was assigned to, and investigated 

by, a MCAQD inspector. A review of all pertinent records from this period indicates that 

MCAQD inspectors observed three PM10 emissions violations of local, state, or federal 

regulations within a 4-mile radius of exceeding monitors (Zuni Hills and Higley). 

On November 2, 2011, a complaint investigation led to the issuance of a violation to the 

owner of a vacant lot for failure to stabilize surface areas that had been disturbed by vehicular 

activity during a temporary carnival. The vacant lot is approximately 1.5 miles northeast of the 

Zuni Hills monitor, and the total disturbed surface area was 0.79 acres. The violation was 

observed at 0700 LST, and a City of Peoria water truck began applying water to the unstable 

areas at approximately 0915 LST. Additionally, a response letter from the parcel owner 

indicated that 3/8-inch gravel had been applied to the property and “No Trespassing” signs were 

posted. The vacant lot was stabilized prior to the November 4 high wind event. 

On November 4, 2011, a complaint investigation led to the issuance of a violation to the 

owner of a vacant lot for failure to stabilize surface areas that had been disturbed by vehicular 

activity. The total unstable area was approximately 0.14 acres. The vacant lot is approximately 

1.5 miles northeast of the Zuni Hills monitor. During the exceptional event, the winds were 

generally from the southwest at the Zuni Hills monitor. 

On November 4, 2011, a complaint investigation led to the issuance of a violation to the 

owner of a vacant lot for failure to prevent vehicle access. The inspector stated that there was a 

small area, approximately 0.01 acres, of unstable soil of caused by foot traffic, bicycles, and 

vehicle use. The vacant lot was stabilized with water, while fences, “no access” signs, and nonerodible materials were installed to further control and stabilize the vacant lot. The vacant lot is 

approximately 3.3 miles northeast of the Higley monitor. During the exceptional event, the 

winds were generally from the south and southwest at the Higley monitor. 

In addition to MCAQD’s efforts in pre-event surveillance and proactive inspections, 

ADEQ’s Agricultural Best Management Practice Program (Ag BMP) inspector also monitors the 

ADEQ Five-Day Dust Control Forecast and the MCAQD air monitoring sites that include realtime data. The ADEQ Ag BMP inspector uses specific knowledge of seasonal activities and 

associations with the local growers and dairymen to communicate the importance of limiting 

dust-generating activities, especially during high wind events. Additional outreach is conducted 

with facility representatives prior to forecast high wind alert days. Should the PM10 readings at 

a MCAQD air monitoring site show a notable increase, the ADEQ Ag BMP inspector is 

dispatched to contact the owners and operators of agricultural fields in the area to discern 

whether their activities are causing negative impacts. The Ag BMP inspector is prepared to 

respond to most agriculture complaints within 24 hours. 

A review of the inspection reports and site visit documentation shows no evidence to 

suggest that agricultural activities produced unusual PM10 emissions. From November 3 

through November 4, 2011, the ADEQ Ag BMP inspector distributed notification of the 

November 4 PM10 HPA to 12 agricultural operations and conducted surveillance near the 

Buckeye monitor on November 4. 
Exceptional Event, Phoenix, November 4, 2011 Not Reasonably Controllable or Preventable 

8 

5.2 Forecasts and Warnings 

Dust forecasts and statements were released prior to the event by both ADEQ and the 

NWS office in Phoenix (Appendix D). For November 3, 2011, ADEQ issued a Maricopa County 

Dust Control Forecast indicating a high risk level for unhealthy PM10. The Dust Control 

Forecast also indicated a potential for strong and gusty winds throughout the area, as well as 

dense blowing and transported dust generated by a very strong trough of low pressure. ADEQ 

also issued a PM10 High Pollution Advisory for Maricopa County for November 4, 2011. 

The NWS in Phoenix issued a Special Weather Statement on Wednesday, November 2, 

2011, indicating that strong winds and blowing dust and sand would be possible on Friday, 

November 4. On Thursday, November 3, the NWS issued a Wind Advisory and Blowing Dust 

Advisory for the Phoenix area effective 1100 to 2000 LST on Friday, November 4, for the 

potential for sustained southerly winds of 25 to 35 mph with gusts to 50 mph and blowing dust 

with visibilities reduced to under 1 mile. This time period corresponds to the period of very high 

PM10 concentrations reported at Phoenix-area monitors. At 1407 LST on Friday, November 3, 

the NWS upgraded the Blowing Dust Advisory to a Dust Storm Warning. NWS offices in 

Tucson and Flagstaff, Arizona, and in Las Vegas, Nevada, also issued statements and/or 

advisories related to strong winds and blowing dust, illustrating the widespread, regional nature 

of this event. 

5.3 Wind Observations 

Wind data during the event (Table 3-1, Figure 3-3 and Appendix A) showed several 

hours of sustained wind speeds of over 20 mph, a few NWS sites with peak sustained winds 

over 25 and as high as 32 mph, and wind gusts frequently over 35 mph coincident with the high 

PM10 concentrations. 

5.4 Summary 

On November 4, 2011, strong winds associated with a cold front transported dust and 

PM10 into the Phoenix PM10 nonattainment area. The source region of the dust that caused the 

exceedances was largely outside the Phoenix PM10 nonattainment area, primarily the deserts 

south of the Phoenix PM10 nonattainment area. The Phoenix area is designated as a serious 

nonattainment area for PM10 and is required to have BACM for all significant 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 the events by regulatory 

agencies and local governments confirmed the uncontrollable nature of the dust emissions; 

therefore, these previously approved required controls are adequate for meeting the 

requirements of an exceptional event and should be considered “reasonable” for these 

purposes. 

Despite the deployment of comprehensive control measures and sophisticated response 

programs, high wind conditions associated with the approaching cold front transported high 

concentrations of PM10 into, and also overwhelmed controls within, the Phoenix PM10

nonattainment area. Widespread sustained winds in excess of 20 mph with some sustained 
Exceptional Event, Phoenix, November 4, 2011 Not Reasonably Controllable or Preventable

9 

winds as high as 32 mph and gusts frequently over 35 mph were strong enough to overwhelm 

available efforts to limit PM10 concentrations during the event. The fact that these were natural 

events involving strong winds that transported PM10 emissions into and across 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 exceedances of November 4, 2011, recorded within the Phoenix PM10

nonattainment area were not reasonably controllable or preventable. 
Exceptional Event, Phoenix, November 4, 2011 But-For Analysis

1 

6. But-For Analysis 

6.1 Discussion 

Section 50.14(c)(3)(iv)(D) in 40 CFR Part 50 requires that an exceptional event 

demonstration satisfy the condition that “[t]here would have been no exceedance or violation but 

for the event.” The prior sections of this submittal have provided detailed information that, in 

regard to the PM10 exceedances at Phoenix area monitors on November 4, 2011, 

 the exceedance was not reasonably controllable or preventable, and 

 there was a clear causal relationship between PM10 transported strong winds originating 

in desert areas outside the Phoenix PM10 nonattainment area and the measured PM10

exceedances in the Phoenix PM10 nonattainment area. 

The weight of evidence in these sections demonstrates that, but for the existence of dust 

emissions generated by strong winds and the associated transport of PM10, there would have 

been no exceedance of the NAAQS for 24-hr average PM10. 

As shown in Section 3, maps and time-series plots of PM10 and wind speeds establish a 

clear causal relationship between the arrival of strong winds associated with an approaching 

cold front and elevated PM10 concentrations at Phoenix-area monitors. Multiple independent 

measurements of wind speed, wind direction, and visibility point to the presence of widespread, 

strong winds as the mechanism for transport of PM10 into the Phoenix nonattainment area. In 

addition, PM10 concentrations were well below the NAAQS on days immediately before and 

after the windblown dust event. The source region for the PM10 is clearly identified as desert 

areas south of the Phoenix PM10 nonattainment area. The weight of evidence presented in this 

submittal provides no alternative that could tie the exceedance of November 4, 2011 to any 

causal source except PM10 transported by strong winds, confirming that there would have been 

no exceedance but for the presence of this uncontrollable natural event. 

As detailed in Section 5, all reasonable control measures were in place and/or 

implemented on a continual basis. Air quality-related inspection and compliance data revealed 

no violations or complaints within three days before and after the time of the event. Local 

regulatory agencies, industry, and the general public were alerted to the possibility of dust 

storms due to strong winds via daily forecasts and media reports. 

6.2 Summary 

The weight of evidence presented in this submittal provides no alternative that could tie 

the exceedance of November 4, 2011, to any causal source other than PM10 transported by 

strong winds associated with an approaching cold front, confirming that there would have been 

no exceedance but for the presence of this uncontrollable natural event. 

Exceptional Event, Phoenix, November 4, 2011 Conclusions 

1

7. Conclusions 

The PM10 exceedances that occurred on November 4, 2011, satisfy the criteria of the 

EER, which states that in order to justify the exclusion of air quality monitoring data, evidence 

must be provided for the following elements: 

 The event satisfies the criteria set forth in 40 CFR 501 (j) that 

a. the event affected air quality, 

b. the event was not reasonably controllable or preventable, and 

c. the event was caused by human activity unlikely to recur in a particular location or 

was a natural event; 

 There is a clear causal relationship between the measurement(s) under consideration 

and the event; 

 The event is associated with a measured concentration(s) in excess of normal historical 

fluctuations; and 

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

7.1 Affects Air Quality 

As stated in the preamble to the EER, 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 exceedances and the event, and that the event is associated with a measured 

concentration in excess of normal historical fluctuations. Given the information presented in 

Sections 2, 3, 4, and 5, we can reasonably conclude that the event in question affected air 

quality. 

7.2 Not Reasonably Controllable or Preventable 

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

controllable or preventable” in order to be defined as an exceptional event. This requirement is 

met by demonstrating that despite reasonable control measures in place within Maricopa 

County, high winds overwhelmed all reasonably available controls (Section 5). The PM10

exceedances discussed in this report were caused by naturally occurring strong winds 

associated with an approaching cold front that transported dust into the Phoenix area from 

areas largely outside the Phoenix PM10 nonattainment area. These facts provide strong 

evidence that the PM10 exceedances on November 4, 2011, were not reasonably controllable or 

preventable. 

7.3 Natural Event 

As discussed above, the PM10 exceedances in the Phoenix area on November 4, 2011, 

were shown to be caused by transport of PM10 into the Phoenix area from widespread strong 

winds associated with an approaching cold front. The event therefore qualifies as a natural 

event. 
Exceptional Event, Phoenix, November 4, 2011 Conclusions

7.4 Clear Causal Relationship 

The following points demonstrate that the high PM10 concentrations were caused by 

windblown dust: 

 Time-series of PM10 concentrations show that the timing of high PM10 at Phoenix area 

monitors was consistent with gusty winds and low visibilities at Phoenix-area 

meteorological stations (Section 3). 

 High PM10 concentrations and gusty winds were reported throughout the Phoenix 

metropolitan area, as well as across much of Arizona, southeastern California, and 

southern Nevada, illustrating the widespread, regional, and uncontrollable nature of this 

event (Sections 3 and 5). 

 PM10 concentrations were well below the NAAQS on days immediately before and after 

the windblown dust event (Section 3). 

 Dry conditions preceding the event resulted in soils that were particularly susceptible to 

particulate suspension by high winds (Section 3). 

 Visibility cameras clearly illustrate the arrival of dust and significant reductions in visibility 

in the Phoenix area coinciding with the sharp increases in PM10 concentrations. 

7.5 Historical Norm 

The 24-hr average PM10 values measured at Phoenix area monitors were historically 

unusual compared to a multi-year data set (Section 4). 

7.6 But For 

On the basis of the weight of evidence described above and in Section 6, the 

exceedances of the federal 24-hr PM10 standard on November 4, 2011, in the Phoenix PM10

nonattainment area would not have occurred but for the high winds and transport of dust from 

areas largely outside the Phoenix PM10 nonattainment area. 

2
Exceptional Event, Phoenix, November 4, 2011 Appendix A 

Appendix A: 

Air Quality and Meteorological Data for Maricopa County 

This section contains time-series of PM10 concentrations and wind data for Phoenix-area 

air quality monitors on November 4 and 5, 2011. The data show a region-wide increase in wind 

speeds and wind gusts coincident with the arrival of dust and high PM10 concentrations. 

Figure A-1. Hourly PM10 concentrations and wind speeds at the Central Phoenix 

monitor on November 4 and 5, 2011. PM10 concentrations and wind speeds sharply 

increased at 1600 LST on November 4, 2011, indicating the arrival of windblown dust. 

1
Exceptional Event, Phoenix, November 4, 2011 Appendix A 

Figure A-2. Hourly PM10 concentrations and wind speeds at the Durango Complex 

monitor on November 4 and 5, 2011. PM10 concentrations and wind speeds sharply 

increased at 1600 LST on November 4, 2011, indicating the arrival of windblown dust. 

2
Exceptional Event, Phoenix, November 4, 2011 Appendix A 

Figure A-3. Hourly PM10 concentrations and wind speeds at the Dysart monitor on 

November 4 and 5, 2011. PM

R R

10 concentrations and wind speeds sharply increased at 

1600 LST on November 4, 2011, indicating the arrival of windblown dust. Note that wind 

speed and wind gust data were not available at 0800 LST on November 4, 2011 at the 

Dysart monitor. 

Figure A-4. Hourly PM10 concentrations and wind speeds at the Glendale monitor on 

November 4 and 5, 2011. PM10 concentrations and wind speeds sharply increased at 

1600 LST on November 4, 2011, indicating the arrival of windblown dust. Note that PM10

concentrations were not available at 1200 or 2300 LST on November 4, 2011 or for the 

entirety of November 5, 2011 at the Glendale monitor. 

3
Exceptional Event, Phoenix, November 4, 2011 Appendix A 

Figure A-5. Hourly PM10 concentrations and wind speeds at the Greenwood monitor on 

November 4 and 5, 2011. PM10 concentrations and wind speeds sharply increased at 

1600 LST on November 4, 2011, indicating the arrival of windblown dust. 

Figure A-6. Hourly PM10 concentrations and wind speeds at the Higley monitor on 

November 4 and 5, 2011. Note that PM10 concentrations were not available between 

1200 and 1400 LST on November 4, 2011 at the Higley monitor. 

4
Exceptional Event, Phoenix, November 4, 2011 Appendix A 

Figure A-7. Hourly PM10 concentrations and wind speeds at the JLG Supersite(3) 

monitor on November 4 and 5, 2011. PM10 concentrations and wind speeds sharply 

increased at 1600 LST on November 4, 2011, indicating the arrival of windblown dust. 

Figure A-8. Hourly PM10 concentrations and wind speeds at the JLG Supersite(4) 

monitor on November 4 and 5, 2011. PM10 concentrations and wind speeds sharply 

increased at 1600 LST on November 4, 2011, indicating the arrival of windblown dust. 

5
Exceptional Event, Phoenix, November 4, 2011 Appendix A 

Figure A-9. Hourly PM10 concentrations and wind speeds at the North Phoenix(2) 

monitor on November 4 and 5, 2011. PM10 concentrations and wind speeds sharply 

increased at 1600 LST on November 4, 2011, indicating the arrival of windblown dust. 

Figure A-10. Hourly PM10 concentrations and wind speeds at the South Phoenix monitor 

on November 4 and 5, 2011. PM10 concentrations and wind speeds sharply increased at 

1600 LST on November 4, 2011, indicating the arrival of windblown dust. Note that PM10

concentrations were not available between 0200 or 0700 LST on November 4, 2011 or at 

0000 LST on November 5, 2011 at the South Phoenix monitor. 

6
Exceptional Event, Phoenix, November 4, 2011 Appendix A 

Figure A-11. Hourly PM10 concentrations and wind speeds at the West 43rd Avenue 

monitor on November 4 and 5, 2011. PM10 concentrations and wind speeds sharply 

increased at 1600 LST on November 4, 2011, indicating the arrival of windblown dust. 

Figure A-12. Hourly PM10 concentrations and wind speeds at the West Chandler 

monitor on November 4 and 5, 2011. PM10 concentrations and wind speeds sharply 

increased at 1400 LST on November 4, 2011, indicating the arrival of windblown dust. 

Note that PM10 concentration data was not available at 0100 LST on November 5, 2011 

at the West Chandler monitor. 

7
Exceptional Event, Phoenix, November 4, 2011 Appendix A 

8

Figure A-13. Hourly PM10 concentrations and wind speeds at the West Phoenix monitor 

on November 4 and 5, 2011. PM10 concentrations and wind speeds sharply increased at 

1500 LST on November 4, 2011, indicating the arrival of windblown dust. 
9 

U.S. Department of Commerce National Oceanic & Atmospheric Administration

QUALITY CONTROLLED LOCAL CLIMATOLOGICAL DATA 

PHOENIX SKY HARBOR INTL AIRPORT (23183) 

PHOENIX, AZ (11/2011)

National Climatic Data Center

Federal Building

151 Patton Avenue

Asheville, North Carolina 28801

Elevation: 1107 ft. above sea level Latitude: 33.427 Longitude: -112.003 Data Version: VER3 

Dry 

Bulb 

Temp

Wet 

Bulb 

Temp

Dew 

Point 

Temp Date Time (LST) Station Type Sky Conditions Visibility (SM) Weather Type

(F) (C) (F) (C) (F) (C)

Rel

Humd

%

Wind

Speed

(MPH)

Wind

Dir

Wind 

Gusts 

(MPH)

Station

Pressure

(in. hg)

Press

Tend

Net

3-hr

Chg

(mb)

Sea 

Level

Pressure

(in. hg)

Report

Type

Precip.

Total

(in)

A

m

(in

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 

04 04 04 04 04 04 04 04 04 04 04 04 04 04 04 04 04 04 04 04 04 04 04 04 04 04 04 04 04 04 04 04 04 04 04

0051 0151 0251 0351 0451 0551 0651 0751 0851 0951 1051 1151 1251 1351 1444 1451 1551 1649 1651 1710 1751 1849 1851 1900 1951 2051 2151 2200 2251 2314 2317 2323 2330 2343 2351

11 11 11 11 11 11 11 11 11 11 11 11 11 11 11 11 11 11 11 11 11 11 11 11 11 11 11 11 11 11 11 11 11 11 11

SCT180 BKN230 SCT180 BKN230 SCT180 BKN230 SCT170 BKN230 SCT170 BKN210 SCT160 BKN210 FEW180 BKN220 BKN240 FEW170 BKN200 BKN240 FEW170 BKN200 BKN240 FEW170 BKN220 BKN250 FEW170 BKN220 BKN250 FEW190 BKN220 BKN250 FEW110 BKN220 BKN250 FEW110 SCT220 FEW033 SCT110 SCT220 FEW037 SCT110 SCT220 FEW039 SCT110 SCT220 FEW027 SCT110 SCT220 SCT027 SCT110 SCT220 SCT027 SCT110 SCT220 SCT032 SCT110 SCT220 BKN027 BKN065 BKN027 BKN065 BKN030 BKN065 BKN060 BKN095 BKN050 OVC065 SCT048 BKN060 BKN095 SCT048 SCT060 BKN090 SCT040 SCT055 BKN090 SCT031 BKN060 OVC090 FEW031CB BKN075 OVC090 FEW031CB BKN075 OVC090 FEW031CB BKN075 OVC090 FEW031CB BKN043 OVC070 FEW031CB BKN043 OVC070

10.00 10.00 10.00 10.00 10.00 10.00 10.00 10.00 10.00 10.00 10.00 10.00 10.00 10.00 10.00 10.00 7.00 2.50 2.50 4.00 6.00 4.00 4.00 5.00 9.00 8.00 9.00 10.00 10.00 1.75 1.25 2.50 7.00 3.00 4.00

BLDU BLDU BLDU BLDU BLDU BLDU BLDU -RA -RA -RA -RA +TSRA -TSRA -TSRA -RA BR -RA BR

6664646464626166677073777983818081757677757271707066626362575557575454

18.917.817.817.817.816.716.118.919.421.122.825.026.128.327.026.727.224.024.425.023.922.021.721.021.118.916.717.016.714.013.014.014.012.012.2

4948484746464647495051535457565657616159595858585758575858545355555353

9.28.78.78.47.87.97.98.49.29.710.511.612.313.713.213.013.616.316.215.014.814.614.414.214.014.414.114.314.412.311.812.912.911.611.6

2929292723272924272626272932323234525145464848484752545455525254545252

-1.7-1.7-1.7-2.8-5.0-2.8-1.7-4.4-2.8-3.3-3.3-2.8-1.70.0 0.0 0.0 1.1 11.0s10.67.0 7.8 9.0 8.9 9.0 8.3 11.112.212.012.811.011.012.012.011.011.1

25 27 27 25 21 26 30 20 22 19 17 16 16 16 17 17 18 45 42 32 36 43 44 46 44 61 75 73 78 83 90 90 90 93 93

3 10 7 8 7 7 6 10 3 8 9 11 9 14 13 14 20 15 14 16 14 15 18 17 15 11 14 11 7 29 23 20 16 25 22

060 100 130 060 110 080 120 140 110 140 130 160 150 170 240 270 190 260 240 210 250 250 260 240 240 250 200 210 VR 210 210 200 210 270 270

18 23 26 25 28 28 28 26 20 23 61 61 33 40 32

28.66 28.64 28.64 28.63 28.62 28.62 28.62 28.62 28.63 28.62 28.61 28.57 28.52 28.47 28.44 28.43 28.43 28.43 28.43 28.43 28.43 28.45 28.45 28.45 28.45 28.46 28.45 28.45 28.43 28.43 28.43 28.43 28.43 28.45 28.45

8 8 0 8 8 5 0 8 

013007000004046001006005

29.79 29.77 29.77 29.76 29.75 29.75 29.75 29.75 29.76 29.76 29.74 29.70 29.65 29.59 M 29.56 29.56 M 29.56 M 29.56 M 29.58 M 29.58 29.59 29.59 M 29.57 M M M M M 29.58

AA AA AA AA AA AA AA AA AA AA AA AA AA AA SP AA AA SP AA SP AA SP AA SP AA AA AA SP AA SP SP SP SP SP AA

0.01 T T 0.24

2929292929292929292929292929292929292929292929292929292929292929292929

Figure A-14. Quality controlled local climatological data hourly observations table for Phoenix Sky Harbor International Airport, Phoenix, Arizona (11/04/2011). Note in the Weather Type column that BLDU (blowing dust) was reported for several hours. For a more detailed explanation of the weather codes shown in the table above, please see http://www.nws.noaa.gov/oso/oso1/oso12/document/guide.shtml. Data 

dynamically generated via http://cdo.ncdc.noaa.gov/qclcd/QCLCD.
10 

U.S. Department of Commerce National Oceanic & Atmospheric Administration QUALITY CONTROLLED LOCAL CLIMATOLOGICAL DATA (final) 

HOURLY OBSERVATIONS TABLE 

PHOENIX DEER VALLEY ARPT (03184) 

PHOENIX, AZ (11/2011) 

National Climatic Data Ce

Federal Bui

151 Patton Av

Asheville, North Carolina 2

Elevation: 1455 ft. above sea level Latitude: 33.688 Longitude: -112.081 Data Version: VER2

Dry 

Bulb

Temp

Wet 

Bulb

Temp

Dew

Point

Temp Date Time (LST) Station Type Sky Conditions Visibility (SM) Weather Type

(F) (C) (F) (C) (F) (C)

Rel

Humd

%

Wind

Speed

(MPH)

Wind

Dir

Wind 

Gusts 

(MPH)

Station 

Pressure

(in. hg)

Press

Tend

Net

3-hr

Chg

(mb)

Sea 

Level

Pressure

(in. hg)

Report

Type

Precip.

Total

(in)

A

m

(in

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 

04 04 04 04 04 04 04 04 04 04 04 04 04 04 04 04 04 04 04 04 04 04 04 04 04 04 04 04 04 04 04 04

0053 0153 0253 0353 0453 0553 0653 0753 0853 0953 1053 1153 1253 1353 1453 1553 1646 1653 1700 1743 1751 1753 1829 1853 1933 1953 2053 2153 2253 2325 2340 2353

12 12 12 12 12 12 12 12 12 12 12 12 12 12 12 12 12 12 12 12 12 12 12 12 12 12 12 12 12 12 12 12

CLR CLR CLR CLR CLR CLR CLR CLR CLR CLR CLR CLR CLR CLR CLR CLR OVC029 OVC029 OVC029 OVC029 OVC031 OVC031 OVC029 OVC027 SCT025 BKN075 OVC095 FEW060 BKN095 BKN048 BKN055 OVC085 BKN050 OVC070 BKN041 BKN048 OVC055 FEW018 BKN048 OVC070 FEW019 BKN039 OVC070 SCT012 BKN024 OVC060

10.00 10.00 10.00 10.00 10.00 10.00 10.00 10.00 10.00 10.00 10.00 10.00 10.00 10.00 10.00 10.00 3.00 3.00 2.50 4.00 4.00 4.00 3.00 4.00 6.00 6.00 10.00 10.00 5.00 6.00 8.00 7.00

HZ HZ HZ HZ HZ HZ HZ HZ HZ HZ -RA -RA -RA BR VCTS -RA -RA -RA

6261585660596364666872737576777773727270706966676666625856555554

16.716.114.413.315.615.017.217.818.920.022.222.823.924.425.025.023.022.222.021.021.020.619.019.419.018.916.714.413.313.013.012.2

4444424144444546474850515353545660605958575756565556555554535152

6.76.55.75.16.56.47.37.68.28.910.010.411.511.712.013.215.315.415.114.213.713.713.313.312.813.012.612.812.111.810.711.0

2020202022232222232425263030303750515048464748474647495352524850

-6.7

-6.7-6.7-6.7-5.6-5.0-5.6-5.6-5.0-4.4-3.9-3.3-1.1-1.1-1.12.810.010.610.09.08.08.39.08.38.08.39.411.711.111.09.010.0

20 20 23 25 23 25 21 20 19 19 17 17 19 18 18 24 44 48 46 46 42 46 52 49 49 51 63 84 87 90 77 86

3 3 0 5 6 8 11 14 10 8 9 9 11 5 11 17 22 18 21 20 22 18 17 20 18 16 21 6 14 18 21 18

100090000090080110130140140130140180170160260230240220230230240240240230220220240200200200210240

18 25 30 29 28 29 32 32 29 29 31 23 33 23 30 29 29

28.28 28.27 28.26 28.25 28.24 28.23 28.23 28.23 28.25 28.25 28.22 28.20 28.15 28.10 28.07 28.06 28.06 28.05 28.05 28.06 28.06 28.05 28.07 28.08 28.09 28.09 28.09 28.08 28.05 28.05 28.06 28.07

6 6 5 8 8 6 3 8 

013008003003042017012012

29.79 29.78 29.77 29.76 29.75 29.75 29.74 29.75 29.76 29.76 29.73 29.70 29.65 29.60 29.57 29.56 M 29.55 M M M 29.56 M 29.59 M 29.59 29.59 29.59 29.55 M M 29.57

AA AA AA AA AA AA AA AA AA AA AA AA AA AA AA AA SP AA SP SP SP AA SP AA SP AA AA AA AA SP SP AA

T 0.03 0.06 0.08

2929292929292929292929292929292929292929292929292929292929292929

Figure A-15. Quality controlled local climatological data hourly observations table for Phoenix Deer Valley Airport, Phoenix, Arizona (11/04/2011). Note in the Weather Type column that HZ (haze) was reported for several hours. Dynamically generated via http://cdo.ncdc.noaa.gov/qclcd/QCLCD.
11 

U.S. Department of Commerce National Oceanic & Atmospheric Administration QUALITY CONTROLLED LOCAL CLIMATOLOGICAL DATA (final) 

HOURLY OBSERVATIONS TABLE 

WILLIAMS GATEWAY AIRPORT (23104) 

PHOENIX, AZ (11/2011) 

National Climatic Data C

Federal Bui

151 Patton Av

Asheville, North Carolina 2

Elevation: 1382 ft. above sea level Latitude: 33.3 Longitude: -111.666 Data Version: VER2

Dry 

Bulb 

Temp

Wet 

Bulb 

Temp

Dew 

Point 

Temp Date Time (LST) Station Type Sky Conditions Visibility (SM) Weather Type

(F) (C) (F) (C) (F) (C)

Rel

Humd

%

Wind

Speed

(MPH)

Wind

Dir

Wind

Gusts

(MPH)

Station 

Pressure 

(in. hg)

Press

Tend

Net

3-hrChg

(mb)

Sea 

Level 

Pressure

(in. hg)

Report

Type

Precip.

Total

(in)

A

m

(in

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 

04 04 04 04 04 04 04 04 04 04 04 04 04 04 04 04 04 04 04 04 04 04 04 04 04 04 04 04 04 04 04 04 04 04 04 04 04 

0015 0035 0055 0115 0135 0155 0215 0235 0255 0315 0335 0355 0415 0435 0455 0515 0547 0650 0747 0847 0949 1047 1147 1247 1347 1402 1456 1547 1647 1755 1850 1947 1955 2015 2035 2047 2055 

0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 

CLR CLR CLR CLR CLR CLR CLR CLR CLR CLR CLR SCT100 CLR CLR CLR CLR FEW150 BKN250 SCT150 BKN250 SCT150 BKN250 SCT150 BKN250 SCT150 BKN250 SCT150 BKN250 FEW150 BKN200 FEW150 BKN200 FEW150 BKN200 FEW150 BKN200 FEW150 BKN200 BKN075 BKN200 FEW150 BKN200 FEW150 BKN200 FEW150 BKN200 OVC CLR VV007 CLR OVC CLR 

10.00 10.00 10.00 10.00 10.00 10.00 10.00 10.00 10.00 10.00 10.00 10.00 10.00 10.00 10.00 10.00 20.00 35.00 35.00 35.00 35.00 35.00 35.00 35.00 4.00 2.50 2.00 2.00 3.00 2.00 2.00 4.00 5.00 1.50 7.00 4.00 3.00 

BLDU BLDU BLDU BLDU BLDU BLDU BLDU HZ -RA HZ 

63636361616161616163636164636363636161727777818284848684827773727270707070

17.0

17.017.016.016.016.016.016.016.017.017.016.018.017.017.017.017.016.016.022.025.025.027.028.029.029.030.029.028.025.023.022.022.021.021.021.021.0

47474846474646474748484647474848474647525353555557575858576162M606060M60

8.1 8.3 8.6 7.7 8.1 7.7 7.7 8.1 8.1 8.6 8.6 7.7 8.5 8.3 8.6 8.6 8.3 7.7 8.1 11.211.511.512.612.813.813.814.614.214.116.216.4M 15.715.315.3M 15.3

27283028302828303030302828283030282830322727282832323434365054545252525452

-3.0-2.0-1.0-2.0-1.0-2.0-2.0-1.0-1.0-1.0-1.0-2.0-2.0-2.0-1.0-1.0-2.0-2.0-1.00.0 -3.0-3.0-2.0-2.00.0 0.0 1.0 1.0 2.0 10.012.012.011.011.011.012.011.0

26 27 29 29 31 29 29 31 31 29 29 29 26 27 29 29 27 29 31 23 16 16 14 14 15 15 16 17 19 39 52 M 50 53 53 M 53 

7 8 6 7 7 10 9 7 7 9 8 10 7 6 0 5 6 3 0 8 14 13 6 6 14 11 14 17 17 17 17 23 28 30 25 23 29 

140 150 140 120 150 140 150 150 130 140 140 160 180 160 000 120 110 120 000 140 140 130 140 180 180 180 220 220 210 220 230 220 240 240 230 220 230 

24 26 29 34 29 29 37 31 34 39 30 39 39 

28.41 28.41 28.41 28.40 28.40 28.39 28.39 28.39 28.39 28.38 28.37 28.37 28.38 28.38 28.38 28.37 28.37 28.37 28.38 28.38 28.37 28.36 28.32 28.27 28.22 28.22 28.19 28.19 28.18 28.18 28.20 M 28.20 28.20 28.20 M 28.21 

M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M 

AA

AA AA AA AA AA AA AA AA AA AA AA AA AA AA AA AA AA AA AA AA AA AA AA AA AA AA AA AA AA AA AA AA AA AA AA AA 

29.29.29.29.29.29.29.29.29.29.29.29.29.29.29.29.29.29.29.29.29.29.29.29.29.29.29.29.29.29.29.29.29.29.29.29.29.
12 

Dry 

Bulb 

Temp

Wet 

Bulb 

Temp

Dew 

Point 

Temp Date Time (LST) Station Type Sky Conditions Visibility (SM) Weather Type

(F) (C) (F) (C) (F) (C)

Rel

Humd

%

Wind

Speed

(MPH)

Wind

Dir

Wind

Gusts

(MPH)

Station 

Pressure 

(in. hg)

Press

Tend

Net

3-hrChg

(mb)

Sea 

Level 

Pressure

(in. hg)

Report

Type

Precip.

Total

(in)

A

m

(in

04 04 04 04 04 04 04 04 04

2115 2135 2155 2215 2235 2255 2315 2335 2355

0 0 0 0 0 0 0 0 0

CLR CLR CLR SCT001 SCT001 SCT001 SCT001 SCT001 SCT001 SCT085

4.00 7.00 10.00 3.00 5.00 2.50 1.75 2.50 7.00

HZ TS -RA HZ TSHZ HZ HZ TS

686868666668646663

20.020.020.019.019.020.018.019.017.0

605959595858565758

15.414.814.815.014.414.313.413.814.6

545252545250505055

12.011.011.012.011.010.010.010.013.0

61 57 57 65 61 53 61 57 75

26 21 22 22 18 26 26 28 20

230 230 230 220 210 220 220 210 230

38 28 36 25 31 33 33 31

28.21 28.21 28.21 28.21 28.20 28.19 28.18 28.18 28.19

M M M M M M M M M

AA AA AA AA AA AA AA AA AA

29.29.29.29.29.29.29.29.29.

Figure A-16. Quality controlled local climatological data hourly observations table for Williams Gateway Airport, Phoenix, Arizona (11/04/2011). 

Note in the Weather Type column that BLDU (blowing dust) and HZ (haze) was reported for several hours. Dynamically generated via http://cdo.ncdc.noaa.gov/qclcd/QCLCD.
13 

U.S. Department of Commerce National Oceanic & Atmospheric Administration QUALITY CONTROLLED LOCAL CLIMATOLOGICAL DATA 

(final) 

HOURLY OBSERVATIONS TABLE 

GLENDALE MUNICIPAL AIRPORT (53126) 

GLENDALE, AZ 

(11/2011) 

National Climatic Data C

Federal Bui

151 Patton Av

Asheville, North Carolina 2

Elevation: 1066 ft. above sea level Latitude: 33.527 Longitude: -112.295 Data Version: VER2

Dry 

Bulb 

Temp

Wet 

Bulb 

Temp

Dew 

Point 

Temp Date Time (LST) Station Type Sky Conditions Visibility (SM) Weather Type

(F) (C) (F) (C) (F) (C)

Rel

Humd

%

Wind

Speed

(MPH)

Wind

Dir

Wind

Gusts

(MPH)

Station 

Pressure 

(in. hg)

Press

Tend

Net

3-hrChg

(mb)

Sea 

Level 

Pressure

(in. hg)

Report

Type

Precip.

Total

(in)

A

m

(in

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 

04 04 04 04 04 04 04 04 04 04 04 04 04 04 04 04

0547 0647 0748 0848 0950 1047 1147 1247 1347 1452 1513 1547 1650 1753 1850 1950

0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

SCT150 SCT250 SCT150 BKN200 SCT150 BKN200 SCT150 BKN200 SCT150 BKN200 SCT150 BKN200 SCT150 BKN200 FEW150 SCT200 FEW150 SCT200 SCT150 BKN200 BKN150 BKN150 BKN150 SCT027 BKN110 OVC060 BKN095

20.00 20.00 20.00 20.00 20.00 20.00 20.00 20.00 20.00 20.00 4.00 3.00 1.00 1.00 3.00 5.00

BLDU BLDU BLDU BLDU BLDU BLDU

54545761646672777979797973707066

12.012.014.016.018.019.022.025.026.026.026.026.023.021.021.019.0

43434446484851545555636361595857

6.2 6.2 6.7 7.8 8.9 9.1 10.512.412.812.817.117.115.914.714.213.9

30302828302828323232525252504850

-1.0 -1.0 -2.0 -2.0 -1.0 -2.0 -2.0 0.0 0.0 0.0 11.0s11.011.010.09.0 10.0

40 40 33 29 28 24 19 19 18 18 39 39 48 49 46 57

0 0 0 0 3 0 0 0 3 5 17 21 20 17 18 16

000 000 000 000 VR 000 000 000 VR 170 220 220 210 210 190 190

23 29 29 25 30 26

28.67 28.67 28.68 28.69 28.69 28.67 28.63 28.58 28.54 28.50 28.50 28.49 28.48 28.50 28.52 28.52

M M M M M M M M M M M M M M M M

AA AA AA AA AA AA AA AA AA AA AA AA AA AA AA AA

29.29.29.29.29.29.29.29.29.29.29.29.29.29.29.29.

Figure A-17. Quality controlled local climatological data hourly observations table for Glendale Municipal Airport, Glendale, Arizona (11/04/2011). Note in the Weather Type column that BLDU (blowing dust) was reported for several hours. Dynamically generated via 

http://cdo.ncdc.noaa.gov/qclcd/QCLCD.
14 

U.S. Department of Commerce National Oceanic & Atmospheric Administration QUALITY CONTROLLED LOCAL CLIMATOLOGICAL DATA (final) HOURLY OBSERVATIONS TABLE 

LUKE AFB AIRPORT (23111), GLENDALE, AZ (11/2011)

National Climatic Data 

Federal Bu

151 Patton A

Asheville, North Carolina 

Elevation: 1085 ft. above sea level Latitude: 33.55, Longitude: -112.366

Dry 

Bulb 

Temp

Wet 

Bulb 

Temp

Dew 

Point 

Temp Date Time (LST) Station Type Sky Conditions Visibility (SM) Weather Type

(F) (C) (F) (C) (F) (C)

Rel

Humd

%

Wind

Speed

(MPH)

Wind

Dir

Wind 

Gusts 

(MPH)

Station

Pressure

(in. hg)

Press

Tend

Net

3-hr

Chg

(mb)

Sea 

Level

Pressure

(in. hg)

Report

Type

Precip.

Total

(in)

A

m

(in

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 

04 04 04 04 04 04 04 04 04 04 04 04 04 04 04 04 04 04 04 04 04 04 04 04 04 04 04 04 04 04 04 04 04 04 04 04 04 04 04 04 04 04 04 04 04 

0055 0155 0255 0355 0455 0555 0655 0755 0855 0955 1055 1155 1255 1355 1455 1555 1558 1602 1615 1622 1636 1642 1647 1655 1657 1658 1659 1712 1728 1732 1735 1737 1738 1742 1748 1752 1753 1755 1757 1758 1800 1800 1801 1806 1807 

0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 

CLR CLR CLR CLR CLR CLR FEW220 CLR CLR CLR CLR CLR CLR FEW140 CLR CLR CLR FEW003 BKN004 BKN004 OVC005 OVC005 OVC005 OVC005 

OVC005 OVC006 OVC005 OVC006 OVC006 OVC006 OVC006 OVC005 VV005 VV005 VV005 OVC005 OVC005 OVC005 OVC005 OVC004 OVC004 OVC VV004 VV003 VV003 

10.00 10.00 10.00 10.00 10.00 10.00 10.00 10.00 10.00 10.00 10.00 10.00 10.00 10.00 10.00 5.00 4.00 4.00 2.50 3.00 3.00 2.50 3.00 3.00 2.50 2.50 2.50 2.50 3.00 2.50 1.75 1.25 1.00 0.75 1.00 1.25 1.75 2.00 1.75 1.75 1.25 1.25 1.00 1.00 0.75 

HZ HZ HZ HZ HZ HZ HZ HZ HZ HZ HZ HZ HZ HZ HZ HZ HZ HZ HZ HZ HZ HZ HZ HZ HZ HZ HZ HZ HZ 

555453535253525460646773767878767575737373737373727272727270707070707070707070707070707070

12.5

12.011.811.811.311.511.212.215.317.719.722.724.325.325.824.224.024.023.023.023.023.023.022.522.022.022.022.022.021.021.021.021.021.021.021.021.021.021.021.021.021.021.021.021.0

4243434242424244474949525355566262626262626261616060606060605959595959595959595959M595959

5.36.16.05.65.75.45.56.48.49.39.310.911.812.813.516.816.916.916.516.516.516.515.916.215.715.715.715.715.715.314.714.714.714.714.714.714.714.714.714.714.7M 14.714.714.7

232930283027293133322829303337535454545454545253525252525252505050505050505050505050505050

-4.9

-1.6-1.3-2.5-1.3-2.6-1.9-0.40.40.0-2.1-1.8-1.20.63.011.712.012.012.012.012.012.011.011.411.011.011.011.011.011.010.010.010.010.010.010.010.010.010.010.010.010.010.010.010.0

29 38 41 38 43 37 41 42 36 30 23 20 18 19 23 45 48 48 52 52 52 52 48 50 50 50 50 50 50 53 49 49 49 49 49 49 49 49 49 49 49 M 49 49 49 

6 8 6 0 3 0 0 5 0 0 3 5 0 0 8 23 24 25 28 22 25 25 25 24 23 24 24 26 24 28 29 31 29 29 29 25 25 31 32 31 30 30 29 33 29 

330 

330 360 000 340 000 000 310 000 000 050 020 000 000 200 230 220 220 230 230 220 220 230 220 220 220 230 230 210 210 220 220 220 220 220 220 220 220 220 220 220 220 220 220 220 

29 30 32 32 31 31 32 37 37 37 37 34 34 38 38 38 38 38 38 38 38 

28.69 28.68 28.66 28.65 28.65 28.64 28.64 28.65 28.66 28.65 28.63 28.59 28.55 28.50 28.47 28.46 28.46 28.46 28.46 28.46 28.46 28.46 28.46 28.46 28.46 28.46 28.46 28.46 28.46 28.46 28.46 28.46 28.46 28.46 28.46 28.46 28.46 28.46 28.46 28.46 28.46 M 28.46 28.46 28.46 

8 6 3 8 8 6 

010010002006044015

29.80 

29.79 29.78 29.76 29.76 29.76 29.77 29.78 29.78 29.77 29.75 29.71 29.66 29.61 29.58 29.57 29.57 29.57 29.57 29.57 29.57 29.57 29.57 29.57 29.57 29.57 29.57 29.57 29.57 29.57 29.57 29.58 29.57 29.57 29.58 29.58 29.58 29.57 29.58 29.58 29.58 29.58 29.58 29.57 29.58 

AA AA AA AA AA AA AA AA AA AA AA AA AA AA AA AA AA AA AA AA AA AA AA AA AA AA AA AA AA AA AA AA AA AA AA AA AA AA AA AA AA SP AA

AA AA 

292929292929292929292929292929292929292929292929292929292929292929292929292929292929292929
15 

Dry 

Bulb 

Temp

Wet 

Bulb 

Temp

Dew 

Point 

Temp Date Time (LST) Station Type Sky Conditions Visibility (SM) Weather Type

(F) (C) (F) (C) (F) (C)

Rel

Humd

%

Wind

Speed

(MPH)

Wind

Dir

Wind 

Gusts 

(MPH)

Station

Pressure

(in. hg)

Press

Tend

Net

3-hr

Chg

(mb)

Sea 

Level

Pressure

(in. hg)

Report

Type

Precip.

Total

(in)

A

m

(in

04 04 04 04 04 04 04 04 04 04 04 04 04 04 04 04 04 04 04 04 04 04 04 04 04 04 04 04 04 04 04 04 04 04 04 04 04 04 04 04 04 04 04 04 04 04 04 04 04

1809 1812 1815 1824 1826 1829 1832 1835 1842 1847 1854 1855 1901 1907 1917 1926 1928 1952 1954 1955 2001 2005 2009 2013 2016 2018 2022 2030 2031 2040 2052 2055 2102 2107 2119 2140 2155 2159 2213 2234 2245 2253 2255 2302 2306 2312 2317 2320 2355

0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

VV003 OVC003 VV003 OVC003 OVC003 OVC003 OVC003 OVC004 OVC004 OVC004 BKN004 BKN004 SCT004 SCT004 FEW015 SCT027 BKN080 SCT027 BKN080 BKN036 BKN055 BKN080 FEW034 BKN042 BKN055 FEW034 BKN046 BKN055 FEW033 BKN045 BKN055 BKN038 BKN048 BKN090 BKN029 BKN037 BKN090 BKN030 BKN037 BKN038 FEW034 OVC042 BKN045 BKN039 OVC049 BKN041 OVC049 BKN050 OVC060 BKN045 OVC055 BKN045 OVC060 FEW042 BKN050 BKN065 FEW042 SCT055 FEW041 SCT060 FEW065 FEW032 SCT075 SCT095 FEW032 SCT070 BKN090 SCT060 BKN080 FEW065 SCT080 BKN070 SCT065 SCT080 SCT065 FEW039 BKN065 FEW035 SCT042 BKN065 FEW034 SCT045 BKN070 FEW034 SCT048 SCT065 FEW026 SCT045 BKN055 FEW032 BKN049 OVC060

1.00 1.25 1.00 1.25 1.50 2.00 1.75 1.75 2.00 3.00 5.00 5.00 5.00 5.00 6.00 7.00 7.00 10.00 10.00 10.00 10.00 9.00 8.00 8.00 8.00 9.00 9.00 10.00 10.00 10.00 10.00 10.00 10.00 10.00 10.00 10.00 10.00 10.00 10.00 10.00 10.00 10.00 10.00 10.00 7.00 7.00 10.00 10.00 10.00

HZ HZ HZ HZ HZ HZ HZ HZ HZ HZ HZ HZ HZ -RA HZ -RA -RA -RA -RA -RA -RA -RA -RA -RA -RA -RA -RA -RA RA -RA -RA -DZ -RA

70707068686868686868686868686664646464656463636361616163636363626161615960616161616161616159575755

21.021.021.020.020.020.020.020.020.020.020.020.120.020.019.018.018.018.018.018.218.017.017.017.016.016.016.017.017.017.017.016.916.016.016.015.015.716.016.016.016.016.016.216.016.015.014.014.012.8

59595958585858585858575758585958585757585758575857575758585858565656565657575656555555555654535352

14.714.714.714.314.314.314.314.314.314.313.814.014.314.315.014.514.514.014.014.214.014.313.714.313.913.913.914.314.614.614.313.513.313.313.313.413.613.913.313.312.712.712.712.713.312.211.711.711.2

50505050505050505050484950505454545252525254525454545454555554525252525454545252505050505250505050

10.0

10.010.010.010.010.010.010.010.010.09.09.510.010.012.012.012.011.011.011.111.012.011.012.012.012.012.012.013.013.012.011.211.011.011.012.012.012.011.011.010.010.09.910.011.010.010.010.010.2

49 49 49 53 53 53 53 53 53 53 49 51 53 53 65 70 70 65 65 63 65 73 68 73 78 78 78 73 75 75 73 70 72 72 72 84 81 78 72 72 67 67 67 67 72 72 78 78 83

29 29 34 30 29 29 29 30 28 30 32 32 31 32 26 23 25 28 29 31 21 26 29 25 23 20 15 13 11 9 24 24 22 22 17 14 14 14 17 20 21 20 20 20 25 24 18 21 13

210 220 220 210 220 220 220 220 220 210 210 210 210 210 200 200 200 210 210 210 210 220 220 220 210 200 200 200 190 190 230 230 230 220 220 200 200 200 190 190 200 190 190 200 230 270 250 240 230

36 36 41 38 38 33 34 34 34 36 37 37 37 38 44 33 34 34 36 36 39 39 39 36 28 28 36 36 29 29

28.46 28.46 28.46 28.46 28.46 28.47 28.47 28.47 28.47 28.47 28.47 28.47 28.47 28.47 28.47 28.47 28.47 28.47 28.47 28.47 28.48 28.47 28.48 28.48 28.49 28.49 28.49 28.49 28.49 28.49 28.49 28.49 28.49 28.49 28.48 28.47 28.47 28.47 28.47 28.46 28.46 28.44 28.44 28.46 28.46 28.46 28.46 28.47 28.48

3 8 

006011

29.58 29.58 29.58 29.58 29.59 29.59 29.59 29.59 29.59 29.59 29.59 29.59 29.60 29.59 29.60 29.60 29.59 29.60 29.60 29.60 29.60 29.60 29.60 29.61 29.62 29.62 29.62 29.62 29.62 29.62 29.62 29.62 29.62 29.61 29.60 29.59 29.59 29.59 29.58 29.57 29.56 29.55 29.55 29.56 29.57 29.56 29.58 29.59 29.59

AA AA AA AA AA AA AA AA AA AA AA AA AA AA AA AA AA AA AA AA AA AA AA AA AA AA AA AA AA AA AA AA AA AA AA AA AA AA AA AA AA AA AA AA AA AA AA AA AA

0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.03 0.03 0.03 0.03 0.03 0.03 0.03 0.03 0.03 0.03 0.03 0.03 T T T T T T T T T T T 0.03 0.03 0.03 0.03 0.03 0.03

29292929292929292929292929292929292929292929292929292929292929292929292929292929292929292929292929

Figure A-18. Quality controlled local climatological data hourly observations table for Luke Air Force Base, Glendale, Arizona (11/04/2011).

Note in the Weather Type column that HZ (haze) was reported for several hours. Dynamically generated via http://cdo.ncdc.noaa.gov/qclcd/QCLCD.
U.S. Department of Commerce 

National Oceanic & Atmospheric Administration QUALITY CONTROLLED LOCAL CLIMATOLOGICAL DATA (final) 

HOURLY OBSERVATIONS TABLE 

CHANDLER MUNICIPAL AIRPORT (53128) 

CHANDLER, AZ (11/2011) 

National Climatic Data C

Federal Bui

151 Patton Av

Asheville, North Carolina 2

Elevation: 1243 ft. above sea level Latitude: 33.268 Longitude: -111.812 Data Version: VER2

Dry 

Bulb 

Temp

Wet 

Bulb 

Temp

Dew 

Point 

Temp Date Time (LST) Station Type Sky Conditions Visibility (SM) Weather Type

(F) (C) (F) (C) (F) (C)

Rel

Humd

%

Wind

Speed

(MPH)

Wind

Dir

Wind

Gusts

(MPH)

Station 

Pressure 

(in. hg)

Press

Tend

Net

3-hrChg

(mb)

Sea 

Level 

Pressure

(in. hg)

Report

Type

Precip.

Total

(in)

A

m

(in

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 

04 04 04 04 04 04 04 04 04 04 04 04 04 04 04 04 04

0550 0647 0747 0847 1047 1147 1247 1335 1352 1450 1547 1654 1750 1852 1925 1950 2048

0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

SCT180 SCT150 BKN210 SCT120 BKN200 SCT120 BKN200 SCT150 BKN200 SCT120 BKN200 BKN200 BKN250 SCT110 SCT110 SCT100 SCT100 SCT100 BKN250 SCT100 BKN200 SCT100 BKN150 SCT050 SCT150 BKN100

15.00 40.00 40.00 40.00 40.00 40.00 25.00 2.00 2.00 1.00 1.00 1.00 2.00 2.00 5.00 5.00 M

BLDU BLDU BLDU BLDU BLDU BLDU BLDU BLDU BLDU

5755616675M8182828281777370707068

14.013.016.019.024.0M 27.028.028.028.027.025.023.021.021.021.020.0

4443475052M5556565656595959595857

6.7 6.1 8.5 10.111.1M 12.913.113.113.113.215.014.814.714.714.213.8

2828323427M3030303032454850504848

-2.0-2.00.0 1.0 -3.0M -1.0-1.0-1.0-1.00.0 7.0 9.0 10.010.09.0 9.0

33 36 34 31 17 M 16 15 15 15 17 32 41 49 49 46 49

13 5 5 8 7 9 15 29 24 34 23 28 17 34 24 24 31

090 150 VR 090 VR 150 150 170 180 180 210 210 210 190 200 200 190

37 38 40 39 32 32 41 31 40

28.48 28.49 28.49 28.49 28.48 28.44 28.39 28.34 28.34 28.31 28.31 28.30 28.30 28.32 28.34 28.34 28.33

M M M M M M M M M M M M M M M M M

AA AA AA AA AA AA AA AA AA AA AA AA AA AA AA AA AA

29.29.29.29.29.29.29.29.29.29.29.29.29.29.29.29.29.

Figure A-19. Quality controlled local climatological data hourly observations table for Chandler Municipal Airport, Chandler, Arizona (11/04/2011). Note in the Weather Type column that BLDU (blowing dust) was reported for several hours. Dynamically generated via 

http://cdo.ncdc.noaa.gov/qclcd/QCLCD.

16 
Exceptional Event, Phoenix, November 4, 2011 Appendix B 

1 

Appendix B: Media Coverage, Videos, and Images 

Video Links

ADEQ visibility cameras in the Phoenix area: 

South Mountain: www.phoenixvis.net/videos/mpeg4/SOMT_11042011.mp4

Estrella Mountains: www.phoenixvis.net/videos/mpeg4/ESMO_11042011.mp4

Camelback Mountains: www.phoenixvis.net/videos/mpeg4/CAME_11042011.mp4

Superstition Mountains: www.phoenixvis.net/videos/mpeg4/SUPM_11042011.mp4

Local citizens often create videos during dust storms, documenting their observations. Here are 

a few links to these videos. 

http://www.youtube.com/watch?v=-ixD2Vx7DPQ

http://www.youtube.com/watch?v=D1ZqJcUxzU8

http://www.youtube.com/watch?v=k2Z1l8Wd77o
Exceptional Event, Phoenix, November 4, 2011 Appendix B 

Articles and Image Links 

http://www.azcentral.com/news/articles/2011/11/04/20111104arizona-drivers-warned-blowingdust-abrk04-ON.html?nclick_check=1

2 

Comment [MJT1]: Did not verify, 

Drought has caused unusually dusty weather in Valley 

by Kelsey Pfeffer and Morgan Sailor - Nov. 4, 2011 09:40 PM 

The Arizona Republic-12 News Breaking News Team 

A severe, ongoing drought has caused some unusually dusty weather in the Valley for this time 

of year. 

On Friday strong winds and blowing dust forced the intermittent closure of Interstate 8 west and 

Interstate 10. The National Weather Service issued a dust-storm warning until late Friday 

spanning the Phoenix, Casa Grande to Gila Bend areas, meteorologist Craig Ellis said. 

Typically there are localized areas of blowing dust, but large gusts have produced significant 

amounts especially along Interstate 8, meteorologist Mike Bruce said. 

Evening showers can tame the blowing dust, but threats of dust storms will continue until 

Arizona gets some significant rain, Bruce said. 

There was an unusually high chance of rain at 80 percent or more in Phoenix, Friday night. The 

National Weather Service predicted rainfall amounts to range from one-tenth inch in the lower 

deserts to one-half inch in the mountains and foothills of Maricopa and Gila counties. 

On Saturday, there is a slight chance of lingering showers in the morning especially in the east 

valley with a forecasted high of 65 degrees, which would tie for the record high hit in both 1895 

and 1925. The National Weather Service expects a partly cloudy day with cool temperatures. 

The clouds are expect to clear up into the evening. 

A strong cold front moved across southwest and south-central Arizona including the greater 

Phoenix area Friday evening. The cold front is expected to move East on Saturday, according to 

the National Weather Service. 

There is a 30 percent chance of showers Sunday night extending through Monday, as another 

storm system rolls through the Valley. There is a chance of blowing dust on Sunday but not to 

the magnitude of Friday's storms, meteorologist Mike Bruce said. 

Temperatures are expected to reach the upper 70s late next week ,which is the average for this 

time of year, Ellis said. 
Exceptional Event, Phoenix, November 4, 2011 Appendix B 

3 

Dust covers the Camelback Mountain in Phoenix on Friday afternoon. The chance of strong 

winds prompted the National Weather Service to issue a wind advisory until 11 pm Friday. 

Credit: Rob Schumacher/The Arizona Republic. 
Exceptional Event, Phoenix, November 4, 2011 Appendix B 

http://www.copanews.com/Article.aspx?ID=3199

Strong winds, blowing dust may affect I-10 and I-8 travel on Friday 

Received article 

Friday, November 4, 2011 

Threat of low visibility, dust storms could slow traffic 

PHOENIX, AZ — With the National Weather Service (NWS) issuing a wind advisory for Friday 

(November 4), motorists in southern Arizona could have their travel affected on two major 

interstates. 

A cold front with strong sustained southwest winds from 25 to 35 mph, including wind gusts up 

to 50 mph, is expected to impact most of the state. Widespread blowing dust is expected along 

stretches of I-10 between Tucson and Phoenix, and from Phoenix to Quartzsite. In addition, 

dust is possible on I-8 between Casa Grande and Yuma. 

In northern Arizona, an unseasonably strong low pressure system and cold front will bring winter 

weather conditions this weekend, and could result in the first significant snowfall of the season, 

according to the NWS. 

The Arizona Department of Transportation (ADOT) urges drivers to take extra precautions as 

strong winds over desert areas can result in sudden periods of limited or zero visibility. Motorists 

play an important role in safety when operating their vehicles during a dust storm. ADOT and 

the Arizona Department of Public Safety recommend the following driving tips when 

encountering a dust storm: 

 Check traffic immediately around your vehicle (front, back, and to the side) and begin slowing 

down. 

 Do not stop in the travel lane unless the vehicle traffic in front of you has come to a stop. 

 Look for a safe place to pull completely off the paved portion of the roadway. 

 Stop the vehicle in a position ensuring it is a safe distance from the main roadway and not 

near where any vehicles may travel. 

 Turn off all vehicle lights. 

 Set your emergency brake and take the foot off the brake. 

 Stay in the vehicle and keep your seat belts on. 

 Wait for the storm to pass over and away from the area before re-entering the roadway. 

ADOT, along with DPS, will continue to work as a public safety team to support Arizona’s 

highways and drivers and will closely monitor conditions on the highways while maintaining 

driver safety. 

Drivers planning trips today morrow are urged to monitor travel conditions by calling 5-1-1 within 

Arizona, 1-888-411-ROAD outside the state, or via the website www.az511.gov. Because 

weather conditions can quickly evolve, drivers are encouraged to regularly check in with 

ADOT’s Traveler Information Service. Motorists should delay or detour travel plans if necessary. 

4 
Exceptional Event, Phoenix, November 4, 2011 Appendix C 

Appendix C: Historical Fluctuation Time Series Graphs 

Figure C-1. 24-hr average PM10 concentrations at the West Phoenix monitor (2007–

2011). The 24-hr average PM10 concentration on November 4, 2011, is shown in red and 

highlighted by the arrow. 

1 
Exceptional Event, Phoenix, November 4, 2011 Appendix C 

Figure C-2. 24-hr average PM10 concentrations at the North Phoenix monitor (2007–

2011). The 24-hr average PM10 concentration on November 4, 2011, is shown in red and 

highlighted by the arrow. 

Figure C-3. 24-hr average PM10 concentrations at the Glendale Phoenix monitor (2007–

2011). The 24-hr average PM10 concentration on November 4, 2011, is shown in red and 

highlighted by the arrow. 

2 
Exceptional Event, Phoenix, November 4, 2011 Appendix C 

Figure C-4. 24-hr average PM10 concentrations at the Central Phoenix monitor (2007–

2011). The 24-hr average PM10 concentration on November 4, 2011, is shown in red and 

highlighted by the arrow. 

Figure C-5. 24-hr average PM10 concentrations at the Greenwood monitor (2007–2011). 

The 24-hr average PM10 concentration on November 4, 2011, is shown in red and 

highlighted by the arrow. 

3 
Exceptional Event, Phoenix, November 4, 2011 Appendix C 

Figure C-6. 24-hr average PM10 concentrations at the South Phoenix monitor (2007–

2011). The 24-hr average PM10 concentration on November 4, 2011, is shown in red and 

highlighted by the arrow. 

Figure C-7. 24-hr average PM10 concentrations at the West Chandler monitor (2007–

2011). The 24-hr average PM10 concentration on November 4, 2011, is shown in red and 

highlighted by the arrow. 

4 
Exceptional Event, Phoenix, November 4, 2011 Appendix C 

Figure C-8. 24-hr average PM10 concentrations at the West 43rd monitor (2007–2011). 

The 24-hr average PM10 concentration on November 4, 2011, is shown in red and 

highlighted by the arrow. 

Figure C-9. 24-hr average PM10 concentrations at the Dysart monitor (2007–2011). The 

24-hr average PM10 concentration on November 4, 2011, is shown in red and highlighted 

by the arrow. 

5 
Exceptional Event, Phoenix, November 4, 2011 Appendix C 

Figure C-10. 24-hr average PM10 concentrations at the Buckeye monitor (2007–2011). 

The 24-hr average PM10 concentration on November 4, 2011, is shown in red and 

highlighted by the arrow. 

Figure C-11. 24-hr average PM10 concentrations at the Zuni Hills monitor (2007–2011). 

The 24-hr average PM10 concentration on November 4, 2011, is shown in red and 

highlighted by the arrow. 

6 
Exceptional Event, Phoenix, November 4, 2011 Appendix C 

Figure C-12. 24-hr average PM10 concentrations at the Durango monitor (2007–2011). 

The 24-hr average PM10 concentration on November 4, 2011, is shown in red and 

highlighted by the arrow. 

Figure C-13. 24-hr average PM10 concentrations at the JLG Supersite monitor (2007–

2011). The 24-hr average PM10 concentration on November 4, 2011, is shown in red and 

highlighted by the arrow. 

7 
Exceptional Event, Phoenix, November 4, 2011 Appendix C 

Figure C-14. 24-hr average PM10 concentrations at the Fort McDowell/Yuma Frank 

monitor (2007–2011). The 24-hr average PM10 concentration on November 4, 2011, is 

shown in red and highlighted by the arrow. 

Figure C-15. 24-hr average PM10 concentrations at the Apache Junction monitor (2007–

2011). The 24-hr average PM10 concentration on November 4, 2011, is shown in red and 

highlighted by the arrow.

8 
Exceptional Event, Phoenix, November 4, 2011 Appendix D 

D-1 

RISK LEVEL

HIGH

+

+

Appendix D: 

ADEQ and NWS Forecast Products 

MARICOPA COUNTY DUST CONTROL FORECAST

ISSUED THURSDAY, NOVEMBER 3, 2011

Three-day weather outlook:

A very strong trough of low pressure will bring unseasonably cool air and significant winds. Blowing dust is expected across a much 

of the desert southwest as gust will likely top 50 mph. There’s a 70% chance of evening showers in Phoenix continuing into early 

Saturday. Winds drop of considerably Saturday afternoon. Daytime temperatures will be in the upper 60s through the weekend with

lows in the 40s. The risk of exceeding the 24-hr PM10 health standard in Phoenix will be HIGH on Friday, dropping to Low by 

Saturday. 

R I S K F A C T O R S

WINDS STAGNATION UNHEALTHY PM-10

Day 1: Fri 11/04/2011

Northwest winds around 

25 to 35 mph are 

expected with gusts near + 

50 mph at times (70% 

chance of showers late). 

Little to not stagnation

is expected. =

Day 2: Sat 11/05/2011

Southwest winds around 

5 to 10 mph are 

expected (10% chance 

for morning showers). 

Increasingly stagnant 

+ conditions will develop 

during the afternoon. 

= LOW

Day 3: Sun 11/06/2011

South-southwest winds 

around 5 to 10 mph are 

expected. 

Rather stagnant 

+ conditions are likely 

much of the day. 

= LOW

EXTENDED OUTLOOK

Day 4: Mon 11/07/2011 West winds around 5 to

10 mph are expected.

Rather stagnant 

conditions are likely 

much of the day. 

= LOW

Day 5: Tue 11/08/2011 Mostly light winds are 

expected. 

Rather stagnant 

conditions are likely 

much of the day. 

= LOW
Exceptional Event, Phoenix, November 4, 2011 Appendix D 

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

help reduce dust pollution. A recorded 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/ozone/ensemble.pdf.

JRP 04/28/2011

D-2 
Exceptional Event, Phoenix, November 4, 2011 Appendix D 

D-3 

FORECAST 

DATE

NOTICES 

(*SEE BELOW 

FOR DETAILS)

AIR POLLUTANT 

YESTERDAY

WED 11/02/2011

DUST

Highest AQI Reading/Site

(Preliminary data only)

TODAY

THU 11/03/2011

TOMORROW

FRI 11/04/2011

(PM10) 

DUST

COUNTY-ISSUED 

NO BURN DAY

EXTENDED

SAT 11/05/2011

O3*

42

MULTIPLE 

LOCATIONS

38

GOOD

35

GOOD

38

GOOD

CO* 8

TEMPE

23

GOOD

9

GOOD

17

GOOD

PM-10* 282

ZUNI HILLS

40

GOOD

195

UNHEALTHY

35

GOOD

PM-2.5*

36

DURANGO & 

DYSART

60

MODERATE

45

GOOD

53

MODERATE

VERY 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 FRIDAY, NOVEMBER 4, 2011

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 microns 

*“Ozone Health Watch” means that the highest concentration of OZONE may approach the federal health standard.
Exceptional Event, Phoenix, November 4, 2011 Appendix D 

“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 concentration 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.

D-4 
Exceptional Event, Phoenix, November 4, 2011 Appendix D 

D-5 

Health message for Thursday, November 3: Unusually sensitive people should 

consider limiting prolonged exertion outdoors.

Health message for Friday, November 4: People with heart or lung disease, older 

adults, and children should avoid all physical activity outdoors. Everyone else 

should avoid prolonged or heavy exertion.

...A PM10 HIGH POLLUTION ADVISORY HAS BEEN ISSUED FOR FRIDAY, NOV. 4, 2011... 

Wednesday’s cold front brought strong winds to the region with gusts reaching 50 mph at times in the 

northwest part of the Valley. It was there that the highest levels of PM10 were recorded (282 AQI at Zuni 

Hills, 76 AQI at Dysart). As winds decreased to a steady 10-20 mph, the air cleared out well across the 

forecast area. Thursday’s winds are considerably lower and will remain that way through early Friday. 

With Wednesday’s event in the books, we’re looking ahead at Friday’s system. This trough of low 

pressure will drop a bit further south, generating much stronger winds across the southwest. Widespread 

dust is likely from southern California east across Arizona deserts including the cities of Yuma, Phoenix, 

Casa Grande and Tucson. The timing of the strongest winds in Phoenix will be between 11am and 11pm. 

Fortunately because the system is dropping further south, it will tap into a good fetch of moisture. We will 

see showers develop across the region around 3-5pm with the heaviest expected around 11pm. Totals will 

generally be around a tenth to a half an inch with more near thunderstorms and in the upslope areas. The 

rain should help wash out any lingering/suspended dust. 

Colder air will fill in behind the system, dropping daytime temperatures into upper 60s Saturday and 

Sunday with lows in the 40s. 

NOTE: Multiple-vehicle accidents are not uncommon along Arizona freeways when similar wind/dust 

events occur. This is especially a concern for drivers along I-10 between California and Phoenix and 

between Phoenix and Tucson, as well as I-8 between Casa Grande and Yuma. Those expecting to travel 

along these routes may want to pay close attention to the Nation Weather Service and Arizona Department

of Transportation for the latest weather information and road conditions. 

Check back tomorrow for the more. Until then, have a good day! -J.Paul

MONITORING SITE MAPS

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

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

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

http://www.airnow.gov/

POLLUTION MONITOR READINGS FOR WEDNESDAY, NOVEMBER 2, 2011

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

Apache Junction (Pinal County) 43 36

Blue Point 46 39

Central Phoenix 44 37

Fountain Hills 47 40

North Phoenix 48 41

Phoenix Supersite 50 42

Pinnacle Peak 49 42

South Phoenix 45 38

South Scottsdale 44 37

West Phoenix 49 42
Exceptional Event, Phoenix, November 4, 2011 Appendix D 

6 

CO (CARBON MONOXIDE)

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

Buckeye 0.2 2

Central Phoenix 0.5 6

Dysart 0.2 2

Glendale 0.2 2

Greenwood 0.6 7

Mesa 0.6 7

North Phoenix 0.5 6

South Phoenix 0.5 6

South Scottsdale 0.6 7

Tempe 0.7 8

West Chandler 0.5 6

West Phoenix 0.5 6

PM-10 (PARTICLES)

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

Buckeye 51.0 46

Central Phoenix 25.7 23

Combs School (Pinal County) 141.3 93

Durango 39.5 26

Dysart 105.0 76

Glendale 35.5 32

Greenwood 37.8 34

Higley 29.6 27

Maricopa (Pinal County) 40.0 37

North Phoenix 22.1 20

Phoenix Supersite 30.0 27

South Phoenix 54.0 49

West Chandler 25.2 23

West Forty Third 37.0 34

West Phoenix 48.4 44

Zuni Hills 441.9 282

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 11.0 36

Dysart 11.2 36

Estrella Mountain Park 7.3 24

Glendale 3.7 12

Phoenix Supersite 5.4 18

North Phoenix 3.8 12

South Phoenix 6.7 22

Vehicle Emissions Lab 3.1 10

West Phoenix 1.6 5
Exceptional Event, Phoenix, November 4, 2011 Appendix D 

7 

Statements, Advisories, and Warnings issued by the National Weather Service office in 

Phoenix, AZ pertaining to this dust storm event: 

WWUS85 KPSR 030213 

SPSPSR 

SPECIAL WEATHER STATEMENT 

NATIONAL WEATHER SERVICE PHOENIX AZ 

713 PM MST WED NOV 2 2011 

AZZ020>028-CAZ030>033-031300- 

LOWER COLORADO RIVER VALLEY AZ-WEST CENTRAL DESERTSNORTHWEST MARICOPA COUNTY-GREATER PHOENIX AREASOUTHERN GILA COUNTY/TONTO NATIONAL FOREST FOOTHILLSYUMA/MARTINEZ LAKE AND VICINITY-SOUTHWEST DESERTSSOUTHWEST MARICOPA COUNTY-NORTHWEST AND NORTH CENTRAL PINAL COUNTYJOSHUA TREE NATIONAL PARK-LOWER COLORADO RIVER VALLEY CARIVERSIDE COUNTY/EASTERN DESERTS-IMPERIAL COUNTYINCLUDING THE CITIES OF...EHRENBERG...PARKER...BOUSE...QUARTZSITE... 

SALOME...BUCKEYE...LAKE PLEASANT...MORRISTOWN...NEW RIVER... 

TONOPAH...WICKENBURG...CAREFREE...CAVE CREEK...CHANDLER... 

FOUNTAIN HILLS...GILBERT...GLENDALE...MESA...PEORIA...PHOENIX... 

SCOTTSDALE...SUN CITY...TEMPE...GLOBE...MIAMI...SAN CARLOS... 

SUPERIOR...TOP-OF-THE-WORLD...ALSO INCLUDING APACHE...BARTLETT... 

CANYON...HORSESHOE...ROOSEVELT...AND SAGUARO LAKES... 

FORTUNA FOOTHILLS...SAN LUIS...SOMERTON...YUMA...DATELAND...TACNA... 

WELLTON...GILA BEND...APACHE JUNCTION...CASA GRANDE...COOLIDGE... 

FLORENCE...COTTONWOOD VISITOR CENTER...KEYS VIEW...LOST HORSE... 

BLYTHE...CHIRIACO SUMMIT...DESERT CENTER...EAGLE MOUNTAIN... 

BRAWLEY...CALEXICO...EL CENTRO...GLAMIS...IMPERIAL... 

AND THE SALTON SEA 

713 PM MST WED NOV 2 2011 /713 PM PDT WED NOV 2 2011/ 

...PACIFIC LOW TO BRING UNSETTLED...WINDY AND MUCH COOLER WEATHER TO 

THE AREA FRIDAY INTO SATURDAY... 

THE SECOND IN A SERIES OF COLD PACIFIC LOW PRESSURE SYSTEMS IS SLATED 

TO MOVE PROGRESSIVELY EAST ACROSS SOUTHEAST CALIFORNIA AND ARIZONA 

FRIDAY INTO SATURDAY...BRINGING WITH IT STRONG GUSTY WINDS...MUCH 

COOLER TEMPERATURES AND SHOWERY CONDITIONS. THE STRONG COLD FRONT 

WILL LOWER TEMPERATURES ACROSS SOUTHEAST CALIFORNIA AND SOUTHWEST 

ARIZONA INTO THE UPPER 60S AND LOW 70S ON FRIDAY. THE FRONT WILL EXIT 

TO THE EAST ON FRIDAY NIGHT AND BY SATURDAY MOST OF THE LOWER 

CALIFORNIA AND ARIZONA DESERTS WILL SEE HIGH TEMPERATURES IN THE 60S. 

STRONG GUSTY SOUTH TO SOUTHWEST WINDS WILL DEVELOP DURING THE LATE 

MORNING AND AFTERNOON HOURS FRIDAY AHEAD OF THE COLD FRONT. SUSTAINED 

SPEEDS BETWEEN 20 AND 30 MPH ARE LIKELY AND PEAK GUSTS COULD REACH TO 

NEAR 50 MPH. WINDS WILL CONTINUE TO BE STRONG AND GUSTY AS THE COLD 

FRONT PASSES AND WILL SWING TOWARDS THE WEST OR NORTHWEST. IT IS 

LIKELY THAT A WIND ADVISORY WILL BE NEEDED ACROSS MUCH OF THE AREA 

DURING THE AFTERNOON AND EVENING HOURS ON FRIDAY. 

GIVEN THE CURRENTLY DRY CONDITIONS...THE STRONG WINDS WILL LIKELY 

GENERATE AREAS OF BLOWING SAND...DUST AND DIRT WHICH WILL 

NECESSITATE THE ISSUANCE OF BOTH DUST STORM ADVISORIES AND DUST STORM 

WARNINGS OVER PORTIONS OF THE LOWER CALIFORNIA AND ARIZONA DESERT 

FRIDAY AFTERNOON AND EVENING. 
Exceptional Event, Phoenix, November 4, 2011 Appendix D 

8 

FINALLY...THERE WILL BE A CHANCE FOR SHOWERS FRIDAY IN SOUTHEAST 

CALIFORNIA...AND AS THE FRONT MOVES ACROSS ARIZONA FRIDAY NIGHT THE 

CHANCES WILL SHIFT INTO SOUTHERN AND SOUTH CENTRAL ARIZONA. SHOWERS 

WILL BE NUMEROUS OVER THE HIGHER TERRAIN OF SOUTHERN GILA COUNTY 

FRIDAY NIGHT. RAINFALL TOTALS OF ONE HALF INCH OR MORE ARE POSSIBLE 

ACROSS SOUTH CENTRAL ARIZONA FRIDAY NIGHT...ESPECIALLY OVER FAVORED 

UPSLOPE AREAS NORTH AND EAST OF PHOENIX. BY SATURDAY MORNING THE COLD 

AIR ASSOCIATED WITH THE FRONT WILL LOWER SNOW LEVELS TO NEAR 5000 

FEET...HOWEVER NO SIGNIFICANT SNOWFALL ACCUMULATIONS ARE EXPECTED AT 

THAT LEVEL. 

STAY UP-TO-DATE ON THE LATEST FORECASTS BY LISTENING TO WEATHER RADIO 

ON THE PUBLIC SERVICE BAND. MORE DETAILED INFORMATION IS AVAILABLE 

FROM THE NATIONAL WEATHER SERVICE IN PHOENIX ON THE INTERNET AT 

WEATHER.GOV/PHOENIX 

WWUS75 KPSR 030958 

NPWPSR 

URGENT - WEATHER MESSAGE 

NATIONAL WEATHER SERVICE PHOENIX AZ 

258 AM MST THU NOV 3 2011 

AZZ021>024-026>028-032200- 

/O.NEW.KPSR.WI.Y.0033.111104T1800Z-111105T0300Z/ 

WEST CENTRAL DESERTS-NORTHWEST MARICOPA COUNTYGREATER PHOENIX AREASOUTHERN GILA COUNTY/TONTO NATIONAL FOREST FOOTHILLSSOUTHWEST DESERTS-SOUTHWEST MARICOPA COUNTYNORTHWEST AND NORTH CENTRAL PINAL COUNTYINCLUDING THE CITIES OF...QUARTZSITE...SALOME...BUCKEYE... 

NEW RIVER...WICKENBURG...MESA...PHOENIX...GLOBE...MIAMI... 

SAN CARLOS...SUPERIOR...TOP-OF-THE-WORLD...TACNA...WELLTON... 

GILA BEND...APACHE JUNCTION...CASA GRANDE...FLORENCE 

258 AM MST THU NOV 3 2011 

...WIND ADVISORY IN EFFECT FROM 11 AM TO 8 PM MST FRIDAY... 

THE NATIONAL WEATHER SERVICE IN PHOENIX HAS ISSUED A WIND 

ADVISORY...WHICH IS IN EFFECT FROM 11 AM TO 8 PM MST FRIDAY. 

* AFFECTED AREA: LA PAZ...YUMA...MARICOPA...NORTHWEST PINAL...AND 

 SOUTHERN GILA COUNTIES. 

* LOCATIONS INCLUDE: THE ENTIRE PHOENIX METROPOLITAN AREA...GILA 

 BEND...TACNA...WELLTON...GLOBE...MIAMI...SAN CARLOS...WICKENBURG 

 ...QUARTZSITE... SALOME...CASA GRANDE...FLORENCE...INTERSTATE TEN 

 FROM NEAR CASA GRANDE WEST THROUGH PHOENIX AND TOWARD QUARTZSITE... 

 AND INTERSTATE EIGHT FROM NEAR CASA GRANDE WEST TOWARD YUMA. 

* TIMING: BEGINNING LATE FRIDAY MORNING AND CONTINUING INTO FRIDAY 

 EVENING. 

* WINDS: SUSTAINED SOUTHERLY WINDS 25 TO 35 MPH GUSTING TO 50 MPH. 

* IMPACTS: TRAVEL MAY BE DIFFICULT...ESPECIALLY ALONG EAST TO WEST 

 ORIENTED ROADS WHICH INCLUDES INTERSTATES EIGHT AND TEN. WIDESPREAD 

 AREAS OF BLOWING DUST ARE LIKELY WITH LOCALIZED AREAS OF VERY DENSE 

 BLOWING DUST POSSIBLE. MOTORISTS SHOULD BE PREPARED FOR VERY QUICK 

 AND DRASTIC REDUCTIONS IN VISIBILITY. SMALL UNSECURED OBJECTS MAY 

 BECOME AIRBORNE. 

PRECAUTIONARY/PREPAREDNESS ACTIONS... 

A WIND ADVISORY MEANS THAT SUSTAINED WIND SPEEDS OF BETWEEN 30 AND 40 

MPH ARE EXPECTED...OR WIND GUSTS OF BETWEEN 40 AND 58 MPH. WINDS THIS 

STRONG CAN MAKE DRIVING DIFFICULT...ESPECIALLY FOR HIGH PROFILE 
Exceptional Event, Phoenix, November 4, 2011 Appendix D 

9 

VEHICLES. IN ADDITION...STRONG WINDS OVER DESERT AREAS COULD RESULT 

IN BRIEFLY LOWERED VISIBILITIES TO WELL UNDER A MILE AT TIMES IN 

BLOWING DUST OR BLOWING SAND. USE EXTRA CAUTION. 

&& 

$$ 

NATIONAL WEATHER SERVICE PHOENIX IS ON THE INTERNET AT 

WEATHER.GOV/PHOENIX 

WWUS85 KPSR 031638 

SPSPSR 

SPECIAL WEATHER STATEMENT 

NATIONAL WEATHER SERVICE PHOENIX AZ 

938 AM MST THU NOV 3 2011 

AZZ020>028-CAZ030>033-041330- 

LOWER COLORADO RIVER VALLEY AZ-WEST CENTRAL DESERTSNORTHWEST MARICOPA COUNTY-GREATER PHOENIX AREASOUTHERN GILA COUNTY/TONTO NATIONAL FOREST FOOTHILLSYUMA/MARTINEZ LAKE AND VICINITY-SOUTHWEST DESERTSSOUTHWEST MARICOPA COUNTY-NORTHWEST AND NORTH CENTRAL PINAL COUNTYJOSHUA TREE NATIONAL PARK-LOWER COLORADO RIVER VALLEY CARIVERSIDE COUNTY/EASTERN DESERTS-IMPERIAL COUNTYINCLUDING THE CITIES OF...EHRENBERG...PARKER...BOUSE...QUARTZSITE... 

SALOME...BUCKEYE...LAKE PLEASANT...MORRISTOWN...NEW RIVER... 

TONOPAH...WICKENBURG...CAREFREE...CAVE CREEK...CHANDLER... 

FOUNTAIN HILLS...GILBERT...GLENDALE...MESA...PEORIA...PHOENIX... 

SCOTTSDALE...SUN CITY...TEMPE...GLOBE...MIAMI...SAN CARLOS... 

SUPERIOR...TOP-OF-THE-WORLD...ALSO INCLUDING APACHE...BARTLETT... 

CANYON...HORSESHOE...ROOSEVELT...AND SAGUARO LAKES... 

FORTUNA FOOTHILLS...SAN LUIS...SOMERTON...YUMA...DATELAND...TACNA... 

WELLTON...GILA BEND...APACHE JUNCTION...CASA GRANDE...COOLIDGE... 

FLORENCE...COTTONWOOD VISITOR CENTER...KEYS VIEW...LOST HORSE... 

BLYTHE...CHIRIACO SUMMIT...DESERT CENTER...EAGLE MOUNTAIN... 

BRAWLEY...CALEXICO...EL CENTRO...GLAMIS...IMPERIAL... 

AND THE SALTON SEA 

938 AM MST THU NOV 3 2011 /938 AM PDT THU NOV 3 2011/ 

...PACIFIC STORM SYSTEM WITH STRONG WINDS...BLOWING DUST...SHOWERS... 

POSSIBLE THUNDERSTORMS...AND MUCH COOLER WEATHER ON THE WAY... 

WINDS FROM THE SOUTH AND WEST ARE EXPECTED TO INCREASE ACROSS 

SOUTHEAST CALIFORNIA...AND SOUTHWEST AND SOUTH-CENTRAL ARIZONA LATE 

FRIDAY MORNING THROUGH FRIDAY EVENING AHEAD OF A PACIFIC COLD FRONT. 

STRONG CROSS WINDS ARE EXPECTED ACROSS SOME ROADS AND HIGHWAYS. THE 

STRONGEST WINDS ARE EXPECTED IN SOUTHWEST AND SOUTH-CENTRAL ARIZONA 

WITH GUSTS TO 50 MPH FRIDAY AFTERNOON AND FRIDAY EVENING. 

THE STRONG GUSTY WINDS ARE EXPECTED TO CAUSE AREAS OF DENSE BLOWING 

SAND AND DUST THE DESERT AREAS. THIS INCLUDES INTERSTATES 10 AND 8 

BETWEEN TUCSON...CASA GRANDE...PHOENIX...GILA BEND...YUMA...AND EL 

CENTRO. THE AREA BETWEEN TUCSON...CASA GRANDE...PHOENIX...AND GILA 

BEND IS ESPECIALLY PRONE TO VERY DENSE BLOWING DUST WITH NEAR ZERO 

VISIBILITY POSSIBLE FRIDAY AFTERNOON AND FRIDAY EVENING. 

THE DENSE BLOWING DUST COULD OCCUR IN THE GREATER PHOENIX AREA DURING 

THE COMMUTER RUSH HOUR LATE FRIDAY AFTERNOON AND EARLY EVENING. 

IF YOU SEE A DUST STORM APPROACHING OR GET CAUGHT IN ONE...PULL OFF 

THE ROAD AS FAR AS SAFELY POSSIBLE...PUT YOUR VEHICLE IN PARK...KEEP 

YOUR FOOT OFF THE BRAKE PEDAL...AND TURN YOUR LIGHTS ALL THE WAY OFF. 

THE PACIFIC COLD FRONT WITH A CHANCE OF SHOWERS AND THUNDERSTORMS WILL 
Exceptional Event, Phoenix, November 4, 2011 Appendix D 

10 

MOVE FROM WEST TO EAST ACROSS SOUTHEAST CALIFORNIA AND SOUTHWEST 

ARIZONA LATE FRIDAY AFTERNOON AND FRIDAY EVENING WITH SHOWERS LIKELY 

IN SOUTH-CENTRAL ARIZONA FRIDAY NIGHT ALONG WITH A CHANCE OF 

THUNDERSTORMS. 

MOST OF THE RAIN IS EXPECTED TO BE IN SOUTH-CENTRAL ARIZONA INCLUDING 

THE GREATER PHOENIX AREA FRIDAY NIGHT. THE SHOWERS AND CHANCE OF 

THUNDERSTORMS WILL PROBABLY NOT REACH THE PHOENIX AREA UNTIL LATE 

FRIDAY EVENING. 

RAINFALL AMOUNTS ARE EXPECTED TO RANGE FROM LESS THAN A TENTH OF AN 

INCH IN SOUTHEAST CALIFORNIA AND SOUTHWEST ARIZONA INCLUDING EL 

CENTRO AND YUMA. RAINFALL AMOUNTS ARE EXPECTED TO RANGE FROM 1 TENTH 

OF AN INCH TO MORE THAN A QUARTER OF AN INCH IN THE SOUTH-CENTRAL 

ARIZONA DESERT INCLUDING THE PHOENIX AREA TO MORE THAN A HALF INCH 

IN THE HIGHER TERRAIN NORTH AND EAST OF THE GREATER PHOENIX AREA. 

COLDER AIR WILL MOVE IN BEHIND THE FRONT WITH EARLY MORNING 

TEMPERATURES DROPPING INTO THE UPPER 30S AND 40S IN MOST DESERT 

LOCATIONS SATURDAY MORNING. AND...COMPARED WITH TODAY...HIGH 

TEMPERATURES ARE EXPECTED TO BE 10 TO 20 DEGREES COLDER SATURDAY WITH 

HIGHS BETWEEN 60 AND 70 IN THE DESERT AREAS INCLUDING PHOENIX...YUMA 

AND EL CENTRO. 

THE SNOW LEVEL WILL LOWER TO NEAR 5000 FEET BY SATURDAY MORNING. 

HOWEVER...MOST OF THE PRECIPITATION WILL HAVE ENDED BY THEN. 

THUS...NO SIGNIFICANT SNOWFALL ACCUMULATION IS EXPECTED AT THAT 

LEVEL. 

STAY UP-TO-DATE ON THE LATEST FORECASTS BY LISTENING TO WEATHER 

RADIO ON THE PUBLIC SERVICE BAND. MORE DETAILED INFORMATION IS 

AVAILABLE FROM THE NATIONAL WEATHER SERVICE IN PHOENIX ON THE 

INTERNET AT 

WEATHER.GOV/PHOENIX 

WWUS75 KPSR 040347 

NPWPSR 

URGENT - WEATHER MESSAGE 

NATIONAL WEATHER SERVICE PHOENIX AZ 

847 PM MST THU NOV 3 2011 

AZZ021>023-026>028-041315- 

/O.NEW.KPSR.DU.Y.0003.111104T1800Z-111105T0300Z/ 

/O.CON.KPSR.WI.Y.0033.111104T1800Z-111105T0300Z/ 

WEST CENTRAL DESERTS-NORTHWEST MARICOPA COUNTYGREATER PHOENIX AREA-SOUTHWEST DESERTS-SOUTHWEST MARICOPA COUNTYNORTHWEST AND NORTH CENTRAL PINAL COUNTYINCLUDING THE CITIES OF...QUARTZSITE...SALOME...BUCKEYE... 

NEW RIVER...WICKENBURG...MESA...PHOENIX...TACNA...WELLTON... 

GILA BEND...APACHE JUNCTION...CASA GRANDE...FLORENCE 

847 PM MST THU NOV 3 2011 

...BLOWING DUST ADVISORY IN EFFECT FROM 11 AM TO 8 PM MST 

FRIDAY... 

...WIND ADVISORY REMAINS IN EFFECT FROM 11 AM TO 8 PM MST 

FRIDAY... 

THE NATIONAL WEATHER SERVICE IN PHOENIX HAS ISSUED A BLOWING DUST 

ADVISORY...WHICH IS IN EFFECT FROM 11 AM TO 8 PM MST FRIDAY. A 

WIND ADVISORY REMAINS IN EFFECT FROM 11 AM TO 8 PM MST FRIDAY. 

* AFFECTED AREA: LA PAZ...YUMA...MARICOPA...NORTHWEST PINAL... 

 AND SOUTHERN GILA COUNTIES. 

* LOCATIONS INCLUDE: GILA BEND...TACNA...WELLTON...BUCKEYE... 
Exceptional Event, Phoenix, November 4, 2011 Appendix D 

11 

 MESA...PHOENIX...NEW RIVER...WICKENBURG...QUARTZSITE... 

 SALOME...APACHE JUNCTION...CASA GRANDE...FLORENCE. AREAS ESPECIALLY 

 IMPACTED BY THE BLOWING DUST ADVISORY INCLUDE THE GREATER PHOENIX 

 AREA SOUTHEASTWARD DOWN THE INTERSTATE 10 CORRIDOR TOWARDS CASA 

 GRANDE AND COOLIDGE. 

* TIMING: BEGINNING LATE FRIDAY MORNING AND CONTINUING INTO 

 FRIDAY EVENING. 

* WINDS: SUSTAINED SOUTHERLY WINDS 25 TO 35 MPH GUSTING TO50 

 MPH. 

* VISIBILITIES: AREAS OF LOWERED VISIBILITY BETWEEN 3 AND 5 MILES 

 LOCALLY BELOW ONE MILE. 

* IMPACTS: TRAVEL MAY BE DIFFICULT...ESPECIALLY ALONG EAST TO WEST 

 ORIENTED ROADS WHICH INCLUDES INTERSTATES EIGHT AND TEN. STRONG 

 CROSSWINDS WILL PRODUCE DANGEROUS DRIVING CONDITIONS FOR DRIVERS OF 

 HIGH PROFILE VEHICLES. WIDESPREAD AREAS OF BLOWING DUST ARE LIKELY 

 WITH LOCALIZED AREAS OF VERY DENSE BLOWING DUST POSSIBLE. MOTORISTS 

 SHOULD BE PREPARED FOR VERY QUICK AND DRASTIC REDUCTIONS IN 

 VISIBILITY. SMALL UNSECURED OBJECTS MAY BECOME AIRBORNE. 

PRECAUTIONARY/PREPAREDNESS ACTIONS... 

A WIND ADVISORY MEANS THAT SUSTAINED WIND SPEEDS OF BETWEEN 

30 AND 40 MPH ARE EXPECTED...OR WIND GUSTS OF BETWEEN 40 AND 

58 MPH. WINDS THIS STRONG CAN MAKE DRIVING DIFFICULT...ESPECIALLY 

FOR HIGH PROFILE VEHICLES. IN ADDITION...STRONG WINDS OVER DESERT 

AREAS COULD RESULT IN BRIEFLY LOWERED VISIBILITIES TO WELL UNDER 

A MILE AT TIMES IN BLOWING DUST OR BLOWING SAND. USE EXTRA 

CAUTION. 

A BLOWING DUST ADVISORY MEANS THAT BLOWING DUST WILL RESTRICT 

VISIBILITIES. SOME LOCATIONS WILL SEE VISIBILITIES FALL BELOW ONE 

MILE. TRAVELERS ARE URGED TO USE EXTRA CAUTION. 

WWUS75 KPSR 041117 

NPWPSR 

URGENT - WEATHER MESSAGE 

NATIONAL WEATHER SERVICE PHOENIX AZ 

417 AM MST FRI NOV 4 2011 

AZZ022-023-027-028-042330- 

/O.EXT.KPSR.WI.Y.0033.111104T1800Z-111105T0600Z/ 

/O.CON.KPSR.DU.Y.0003.111104T1800Z-111105T0300Z/ 

NORTHWEST MARICOPA COUNTY-GREATER PHOENIX AREASOUTHWEST MARICOPA COUNTYNORTHWEST AND NORTH CENTRAL PINAL COUNTYINCLUDING THE CITIES OF...BUCKEYE...NEW RIVER...WICKENBURG... 

MESA...PHOENIX...GILA BEND...APACHE JUNCTION...CASA GRANDE... 

FLORENCE 

417 AM MST FRI NOV 4 2011 

...WIND ADVISORY NOW IN EFFECT FROM 11 AM THIS MORNING TO 11 PM 

MST THIS EVENING... 

...BLOWING DUST ADVISORY REMAINS IN EFFECT FROM 11 AM THIS 

MORNING TO 8 PM MST THIS EVENING... 

THE WIND ADVISORY IS NOW IN EFFECT FROM 11 AM THIS MORNING TO 

11 PM MST THIS EVENING. A BLOWING DUST ADVISORY REMAINS IN EFFECT 

FROM 11 AM THIS MORNING TO 8 PM MST THIS EVENING. 

* AFFECTED AREA: MARICOPA...AND NORTHWEST PINAL COUNTIES FOR BOTH 

 DUST AND WINDS. 

* LOCATIONS INCLUDE: DUST PRONE AREAS NEAR FARM FIELDS AND 
Exceptional Event, Phoenix, November 4, 2011 Appendix D 

12 

 CONSTRUCTION SITES WILL BE MOST SUSCEPTIBLE...ESPECIALLY THE 

 INTERSTATE 10 CORRIDOR THROUGH PINAL COUNTY. OTHERWISE...STRONG 

 WINDS WILL AFFECT LOCATIONS INCLUDING...BUT NOT LIMITED TO...GILA 

 BEND...TACNA...WELLTON...BUCKEYE... MESA...PHOENIX...NEW 

 RIVER...WICKENBURG...QUARTZSITE... SALOME...APACHE JUNCTION...CASA 

 GRANDE...FLORENCE. 

* TIMING: BEGINNING LATE THIS MORNING AND CONTINUING THROUGH THIS 

 EVENING. 

* WINDS: SUSTAINED SOUTH AND SOUTHWESTERLY WINDS 25 TO 35 MPH GUSTING 

 40 TO 50 MPH. 

* VISIBILITIES: BROAD AREAS REDUCED TO 3 TO 5 MILES...LOCALLY BELOW ONE 

 MILE. 

* IMPACTS: BLOWING DUST WILL CREATE HAZARDOUS DRIVING CONDITIONS DUE 

 TO REDUCED VISIBILITIES. STRONG WINDS WILL MAKE VEHICLE HANDLING 

 MORE DIFFICULT DUE TO CROSS-WINDS...ESPECIALLY FOR HIGH PROFILE 

 VEHICLES. IN ADDITION...SMALL UNSECURED OBJECTS AROUND HOMES AND 

 BUSINESSES MAY BECOME AIRBORNE. 

PRECAUTIONARY/PREPAREDNESS ACTIONS... 

MOTORISTS SHOULD USE EXTRA CAUTION AND BE PREPARED FOR VERY QUICK AND 

DRASTIC REDUCTIONS IN VISIBILITY...ESPECIALLY ALONG INTERSTATES 10 

AND 8. IF YOU ENCOUNTER VERY LOW VISIBILITY ON THE ROADWAY...PULL 

OFF THE ROAD AS FAR AS POSSIBLE AND PARK...TURN OFF THE LIGHTS AND 

KEEP YOUR FOOT OFF THE BRAKE. 

WWUS75 KPSR 042107 

NPWPSR 

URGENT - WEATHER MESSAGE 

NATIONAL WEATHER SERVICE PHOENIX AZ 

207 PM MST FRI NOV 4 2011 

AZZ023-027-028-050600- 

/O.UPG.KPSR.DU.Y.0003.000000T0000Z-111105T0300Z/ 

/O.NEW.KPSR.DS.W.0024.111104T2107Z-111105T0300Z/ 

/O.CON.KPSR.WI.Y.0033.000000T0000Z-111105T0600Z/ 

GREATER PHOENIX AREA-SOUTHWEST MARICOPA COUNTYNORTHWEST AND NORTH CENTRAL PINAL COUNTYINCLUDING THE CITIES OF...BUCKEYE...MESA...PHOENIX...GILA BEND... 

APACHE JUNCTION...CASA GRANDE...FLORENCE 

207 PM MST FRI NOV 4 2011 

...DUST STORM WARNING IN EFFECT UNTIL 8 PM MST THIS EVENING... 

...WIND ADVISORY REMAINS IN EFFECT UNTIL 11 PM MST THIS 

EVENING... 

THE NATIONAL WEATHER SERVICE IN PHOENIX HAS ISSUED A DUST STORM 

WARNING...WHICH IS IN EFFECT UNTIL 8 PM MST THIS EVENING. THE 

BLOWING DUST ADVISORY IS NO LONGER IN EFFECT. A WIND ADVISORY 

REMAINS IN EFFECT UNTIL 11 PM MST THIS EVENING. 

* AFFECTED AREA: MARICOPA...AND NORTHWEST PINAL COUNTIES FOR 

 BOTH DUST AND WINDS. 

* LOCATIONS INCLUDE: INTERSTATE 10 BETWEEN PHOENIX AND CASA 

 GRANDE...HIGHWAY 347 BETWEEN PHOENIX AND MARICOPA...AND INTERSTATE 

 8 BETWEEN GILA BEND AND CASA GRANDE. OTHER LOCATIONS INCLUDE BUT 

 ARE NOT LIMITED TO FLORENCE JUNCTION...COOLIDGE AND FLORENCE. 

* TIMING: CONTINUING THROUGH 8 PM THIS EVENING. 

* WINDS: SUSTAINED SOUTH AND SOUTHWESTERLY WINDS 25 TO 35 MPH GUSTING 

 TO 45 MPH. 

* VISIBILITIES: AREAS REDUCED DOWN TO 3 TO 5 MILES IN BLOWING 
Exceptional Event, Phoenix, November 4, 2011 Appendix D 

13 

 DUST...LOCALLY BELOW ONE QUARTER MILE IN DUST PRONE LOCATIONS. 

* IMPACTS: BLOWING DUST WILL CREATE HAZARDOUS DRIVING CONDITIONS 

 DUE TO REDUCED VISIBILITIES. STRONG WINDS WILL MAKE VEHICLE 

 HANDLING MORE DIFFICULT DUE TO CROSS-WINDS...ESPECIALLY FOR 

 HIGH PROFILE VEHICLES. IN ADDITION...SMALL UNSECURED OBJECTS 

 AROUND HOMES AND BUSINESSES MAY BECOME AIRBORNE. 

PRECAUTIONARY/PREPAREDNESS ACTIONS... 

MOTORISTS SHOULD USE EXTRA CAUTION AND BE PREPARED FOR VERY QUICK 

AND DRASTIC REDUCTIONS IN VISIBILITY...ESPECIALLY ALONG 

INTERSTATES 10 AND 8. IF YOU ENCOUNTER VERY LOW VISIBILITY ON THE 

ROADWAY...PULL OFF THE ROAD AS FAR AS POSSIBLE AND PARK...TURN 

OFF THE LIGHTS AND KEEP YOUR FOOT OFF THE BRAKE. 

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. 

A WIND ADVISORY MEANS THAT SUSTAINED WIND SPEEDS OF BETWEEN 

30 AND 40 MPH ARE EXPECTED...OR WIND GUSTS OF BETWEEN 40 AND 

58 MPH. WINDS THIS STRONG CAN MAKE DRIVING DIFFICULT...ESPECIALLY 

FOR HIGH PROFILE VEHICLES. IN ADDITION...STRONG WINDS OVER DESERT 

AREAS COULD RESULT IN BRIEFLY LOWERED VISIBILITIES TO WELL UNDER 

A MILE AT TIMES IN BLOWING DUST OR BLOWING SAND. USE EXTRA 

CAUTION. 

AZZ022-050600- 

/O.CON.KPSR.DU.Y.0003.000000T0000Z-111105T0300Z/ 

/O.CON.KPSR.WI.Y.0033.000000T0000Z-111105T0600Z/ 

NORTHWEST MARICOPA COUNTYINCLUDING THE CITIES OF...BUCKEYE...NEW RIVER...WICKENBURG 

207 PM MST FRI NOV 4 2011 

...BLOWING DUST ADVISORY REMAINS IN EFFECT UNTIL 8 PM MST THIS 

EVENING... 

...WIND ADVISORY REMAINS IN EFFECT UNTIL 11 PM MST THIS 

EVENING... 

A BLOWING DUST ADVISORY REMAINS IN EFFECT UNTIL 8 PM MST THIS 

EVENING. A WIND ADVISORY REMAINS IN EFFECT UNTIL 11 PM MST THIS 

EVENING. 

* AFFECTED AREA: MARICOPA...AND NORTHWEST PINAL COUNTIES FOR 

 BOTHDUST AND WINDS. 

* LOCATIONS INCLUDE: DUST PRONE AREAS NEAR FARM FIELDS AND 

 CONSTRUCTION SITES WILL BE MOST SUSCEPTIBLE...ESPECIALLY THE 

 INTERSTATE 10 CORRIDOR THROUGH PINAL COUNTY. OTHERWISE... 

 STRONG WINDS WILL AFFECT LOCATIONS INCLUDING...BUT NOT 

 LIMITED TO...GILABEND...TACNA...WELLTON...BUCKEYE... MESA... 

 PHOENIX...NEW RIVER...WICKENBURG...QUARTZSITE... SALOME... 

 APACHE JUNCTION...CASA GRANDE...FLORENCE. 

* TIMING: CONTINUING THROUGH THIS EVENING. 

* WINDS: SUSTAINED SOUTH AND SOUTHWESTERLY WINDS 25 TO 35 MPH 

 GUSTING 40 TO 50 MPH. 
Exceptional Event, Phoenix, November 4, 2011 Appendix D 

14 

* VISIBILITIES: BROAD AREAS REDUCED TO 3 TO 5 MILES...LOCALLY 

 BELOW ONE MILE. 

* IMPACTS: BLOWING DUST WILL CREATE HAZARDOUS DRIVING CONDITIONS 

 DUE TO REDUCED VISIBILITIES. STRONG WINDS WILL MAKE VEHICLE 

 HANDLING MORE DIFFICULT DUE TO CROSS-WINDS...ESPECIALLY FOR 

 HIGH PROFILE VEHICLES. IN ADDITION...SMALL UNSECURED OBJECTS 

 AROUND HOMES AND BUSINESSES MAY BECOME AIRBORNE. 

PRECAUTIONARY/PREPAREDNESS ACTIONS... 

MOTORISTS SHOULD USE EXTRA CAUTION AND BE PREPARED FOR VERY QUICK 

AND DRASTIC REDUCTIONS IN VISIBILITY...ESPECIALLY ALONG 

INTERSTATES 10 AND 8. IF YOU ENCOUNTER VERY LOW VISIBILITY ON THE 

ROADWAY...PULL OFF THE ROAD AS FAR AS POSSIBLE AND PARK...TURN 

OFF THE LIGHTS AND KEEP YOUR FOOT OFF THE BRAKE. 

WWUS75 KPSR 042107 

NPWPSR 

URGENT - WEATHER MESSAGE 

NATIONAL WEATHER SERVICE PHOENIX AZ 

207 PM MST FRI NOV 4 2011 

AZZ023-027-028-050600- 

/O.UPG.KPSR.DU.Y.0003.000000T0000Z-111105T0300Z/ 

/O.NEW.KPSR.DS.W.0024.111104T2107Z-111105T0300Z/ 

/O.CON.KPSR.WI.Y.0033.000000T0000Z-111105T0600Z/ 

GREATER PHOENIX AREA-SOUTHWEST MARICOPA COUNTYNORTHWEST AND NORTH CENTRAL PINAL COUNTYINCLUDING THE CITIES OF...BUCKEYE...MESA...PHOENIX...GILA BEND... 

APACHE JUNCTION...CASA GRANDE...FLORENCE 

207 PM MST FRI NOV 4 2011 

...DUST STORM WARNING IN EFFECT UNTIL 8 PM MST THIS EVENING... 

...WIND ADVISORY REMAINS IN EFFECT UNTIL 11 PM MST THIS 

EVENING... 

THE NATIONAL WEATHER SERVICE IN PHOENIX HAS ISSUED A DUST STORM 

WARNING...WHICH IS IN EFFECT UNTIL 8 PM MST THIS EVENING. THE 

BLOWING DUST ADVISORY IS NO LONGER IN EFFECT. A WIND ADVISORY 

REMAINS IN EFFECT UNTIL 11 PM MST THIS EVENING. 

* AFFECTED AREA: MARICOPA...AND NORTHWEST PINAL COUNTIES FOR 

 BOTH DUST AND WINDS. 

* LOCATIONS INCLUDE: INTERSTATE 10 BETWEEN PHOENIX AND CASA 

 GRANDE...HIGHWAY 347 BETWEEN PHOENIX AND MARICOPA...AND INTERSTATE 

 8 BETWEEN GILA BEND AND CASA GRANDE. OTHER LOCATIONS INCLUDE BUT 

 ARE NOT LIMITED TO FLORENCE JUNCTION...COOLIDGE AND FLORENCE. 

* TIMING: CONTINUING THROUGH 8 PM THIS EVENING. 

* WINDS: SUSTAINED SOUTH AND SOUTHWESTERLY WINDS 25 TO 35 MPH GUSTING 

 TO 45 MPH. 

* VISIBILITIES: AREAS REDUCED DOWN TO 3 TO 5 MILES IN BLOWING 

 DUST...LOCALLY BELOW ONE QUARTER MILE IN DUST PRONE LOCATIONS. 

* IMPACTS: BLOWING DUST WILL CREATE HAZARDOUS DRIVING CONDITIONS 

 DUE TO REDUCED VISIBILITIES. STRONG WINDS WILL MAKE VEHICLE 

 HANDLING MORE DIFFICULT DUE TO CROSS-WINDS...ESPECIALLY FOR 

 HIGH PROFILE VEHICLES. IN ADDITION...SMALL UNSECURED OBJECTS 

 AROUND HOMES AND BUSINESSES MAY BECOME AIRBORNE. 

PRECAUTIONARY/PREPAREDNESS ACTIONS... 

MOTORISTS SHOULD USE EXTRA CAUTION AND BE PREPARED FOR VERY QUICK 

AND DRASTIC REDUCTIONS IN VISIBILITY...ESPECIALLY ALONG 

INTERSTATES 10 AND 8. IF YOU ENCOUNTER VERY LOW VISIBILITY ON THE 
Exceptional Event, Phoenix, November 4, 2011 Appendix D 

15 

ROADWAY...PULL OFF THE ROAD AS FAR AS POSSIBLE AND PARK...TURN 

OFF THE LIGHTS AND KEEP YOUR FOOT OFF THE BRAKE. 

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. 

A WIND ADVISORY MEANS THAT SUSTAINED WIND SPEEDS OF BETWEEN 

30 AND 40 MPH ARE EXPECTED...OR WIND GUSTS OF BETWEEN 40 AND 

58 MPH. WINDS THIS STRONG CAN MAKE DRIVING DIFFICULT...ESPECIALLY 

FOR HIGH PROFILE VEHICLES. IN ADDITION...STRONG WINDS OVER DESERT 

AREAS COULD RESULT IN BRIEFLY LOWERED VISIBILITIES TO WELL UNDER 

A MILE AT TIMES IN BLOWING DUST OR BLOWING SAND. USE EXTRA 

CAUTION. 

AZZ022-050600- 

/O.CON.KPSR.DU.Y.0003.000000T0000Z-111105T0300Z/ 

/O.CON.KPSR.WI.Y.0033.000000T0000Z-111105T0600Z/ 

NORTHWEST MARICOPA COUNTYINCLUDING THE CITIES OF...BUCKEYE...NEW RIVER...WICKENBURG 

207 PM MST FRI NOV 4 2011 

...BLOWING DUST ADVISORY REMAINS IN EFFECT UNTIL 8 PM MST THIS 

EVENING... 

...WIND ADVISORY REMAINS IN EFFECT UNTIL 11 PM MST THIS 

EVENING... 

A BLOWING DUST ADVISORY REMAINS IN EFFECT UNTIL 8 PM MST THIS 

EVENING. A WIND ADVISORY REMAINS IN EFFECT UNTIL 11 PM MST THIS 

EVENING. 

* AFFECTED AREA: MARICOPA...AND NORTHWEST PINAL COUNTIES FOR 

 BOTHDUST AND WINDS. 

* LOCATIONS INCLUDE: DUST PRONE AREAS NEAR FARM FIELDS AND 

 CONSTRUCTION SITES WILL BE MOST SUSCEPTIBLE...ESPECIALLY THE 

 INTERSTATE 10 CORRIDOR THROUGH PINAL COUNTY. OTHERWISE... 

 STRONG WINDS WILL AFFECT LOCATIONS INCLUDING...BUT NOT 

 LIMITED TO...GILABEND...TACNA...WELLTON...BUCKEYE... MESA... 

 PHOENIX...NEW RIVER...WICKENBURG...QUARTZSITE... SALOME... 

 APACHE JUNCTION...CASA GRANDE...FLORENCE. 

* TIMING: CONTINUING THROUGH THIS EVENING. 

* WINDS: SUSTAINED SOUTH AND SOUTHWESTERLY WINDS 25 TO 35 MPH 

 GUSTING 40 TO 50 MPH. 

* VISIBILITIES: BROAD AREAS REDUCED TO 3 TO 5 MILES...LOCALLY 

 BELOW ONE MILE. 

* IMPACTS: BLOWING DUST WILL CREATE HAZARDOUS DRIVING CONDITIONS 

 DUE TO REDUCED VISIBILITIES. STRONG WINDS WILL MAKE VEHICLE 

 HANDLING MORE DIFFICULT DUE TO CROSS-WINDS...ESPECIALLY FOR 

 HIGH PROFILE VEHICLES. IN ADDITION...SMALL UNSECURED OBJECTS 

 AROUND HOMES AND BUSINESSES MAY BECOME AIRBORNE. 

PRECAUTIONARY/PREPAREDNESS ACTIONS... 

MOTORISTS SHOULD USE EXTRA CAUTION AND BE PREPARED FOR VERY QUICK 

AND DRASTIC REDUCTIONS IN VISIBILITY...ESPECIALLY ALONG 
Exceptional Event, Phoenix, November 4, 2011 Appendix D 

16 

INTERSTATES 10 AND 8. IF YOU ENCOUNTER VERY LOW VISIBILITY ON THE 

ROADWAY...PULL OFF THE ROAD AS FAR AS POSSIBLE AND PARK...TURN 

OFF THE LIGHTS AND KEEP YOUR FOOT OFF THE BRAKE. 

WWUS75 KPSR 050309 

NPWPSR 

URGENT - WEATHER MESSAGE 

NATIONAL WEATHER SERVICE PHOENIX AZ 

809 PM MST FRI NOV 4 2011 

AZZ023-027-028-050600- 

/O.EXP.KPSR.DS.W.0024.000000T0000Z-111105T0300Z/ 

/O.CON.KPSR.WI.Y.0033.000000T0000Z-111105T0600Z/ 

GREATER PHOENIX AREA-SOUTHWEST MARICOPA COUNTYNORTHWEST AND NORTH CENTRAL PINAL COUNTYINCLUDING THE CITIES OF...BUCKEYE...MESA...PHOENIX...GILA BEND... 

APACHE JUNCTION...CASA GRANDE...FLORENCE 

809 PM MST FRI NOV 4 2011 

...WIND ADVISORY REMAINS IN EFFECT UNTIL 11 PM MST THIS 

EVENING... 

...DUST STORM WARNING EXPIRED AT 8 PM MST THIS EVENING... 

THE DUST STORM WARNING EXPIRED AT 8 PM MST THIS EVENING. A WIND 

ADVISORY REMAINS IN EFFECT UNTIL 11 PM MST THIS EVENING. 

* AFFECTED AREA: SOUTHWEST MARICOPA...NORTHWEST PINAL COUNTIES AND 

 THE GREATER PHOENIX AREA. 

* LOCATIONS INCLUDE: GILA BEND...BUCKEYE...MESA...PHOENIX... 

 APACHE JUNCTION...CASA GRANDE...FLORENCE 

* TIMING: CONTINUING THROUGH 11 PM THIS EVENING. 

* WINDS: SUSTAINED SOUTH AND SOUTHWESTERLY WINDS 25 TO 35 MPH GUSTING 

 TO NEAR 45 MPH. 

* IMPACTS: STRONG WINDS WILL MAKE VEHICLE HANDLING MORE DIFFICULT 

 DUE TO CROSS- WINDS... ESPECIALLY FOR HIGH PROFILE VEHICLES. IN 

 ADDITION...SMALL UNSECURED OBJECTS AROUND HOMES AND BUSINESSES MAY 

 BECOME AIRBORNE. 

PRECAUTIONARY/PREPAREDNESS ACTIONS... 

MOTORISTS SHOULD USE EXTRA CAUTION AND BE PREPARED FOR VERY QUICK 

AND DRASTIC REDUCTIONS IN VISIBILITY...ESPECIALLY ALONG 

INTERSTATES 10 AND 8. IF YOU ENCOUNTER VERY LOW VISIBILITY ON THE 

ROADWAY...PULL OFF THE ROAD AS FAR AS POSSIBLE AND PARK...TURN 

OFF THE LIGHTS AND KEEP YOUR FOOT OFF THE BRAKE. 

AZZ022-023-027-028-050700- 

/O.CAN.KPSR.WI.Y.0033.000000T0000Z-111105T0600Z/ 

NORTHWEST MARICOPA COUNTY-GREATER PHOENIX AREASOUTHWEST MARICOPA COUNTYNORTHWEST AND NORTH CENTRAL PINAL COUNTYINCLUDING THE CITIES OF...BUCKEYE...NEW RIVER...WICKENBURG... 

MESA...PHOENIX...GILA BEND...APACHE JUNCTION...CASA GRANDE... 

FLORENCE... 

1053 PM MST FRI NOV 4 2011 

...WIND ADVISORY IS CANCELLED... 

THE NATIONAL WEATHER SERVICE IN PHOENIX HAS CANCELLED THE WIND 

ADVISORY FOR MARICOPA COUNTY AND NORTHWEST PINAL COUNTY. WINDS ACROSS 

MARICOPA COUNTY...NORTHWEST PINAL COUNTY AND THE GREATER PHOENIX AREA 

HAVE STAYED BELOW WIND ADVISORY CRITERIA FOR THE MOST PART SINCE 9 PM 
Exceptional Event, Phoenix, November 4, 2011 Appendix D 

17 

AND ARE NOT EXPECTED TO STRENGTHEN SIGNIFICANTLY FOR THE REST OF 

TONIGHT. THUS THE WIND ADVISORY HAS BEEN CANCELLED. HOWEVER...IT IS 

POSSIBLE THAT WHEN THE COLD FRONT PASSES THROUGH THE AREA LATER 

TONIGHT...GUSTY WINDS TO NEAR 40 MPH MAY BRIEFLY OCCUR. OVERALL WINDS 

SHOULD REMAIN BELOW 30 MPH FOR THE REST OF TONIGHT. 
Exceptional Event, Phoenix, November 4, 2011 Appendix E 

1 

Appendix E: 

Affidavit of Public Notice