Drought in Arizona, August 1 to 31, 2011

Name: Drought in Arizona, August 1 to 31, 2011
Start: 2011-08-01T00:00
End: 2011-08-31T23:59
Location: Arizona

August 1 to 31, 2011 · NWS TWC · 14 events in 14 counties and zones

Long term drought conditions continued in August although minor improvement due to beneficial monsoon rain, occurred across parts of Cochise, Graham and Greenlee Counties.

Where it happened

Every event with a place to put it; 14 filed by county or forecast zone are drawn at its center, in a lighter ring. Tap one for its entry below.

Tornadoes
Tropical storms and surge
Floods
Wind
Hail
Winter weather
Heat and drought
Cold
Fire, smoke and dust
Marine and coastal
Other

Open the live radar over this ground

The toll

Deaths: 0
Injuries: 0
Property damage: None recorded
Crop damage: None recorded
Events: 14

Deaths and injuries are direct and indirect together, as the offices filed them. Damage is property and crops in the dollars of the year, not adjusted for inflation, and only where an office estimated it.

What happened

The episode as NWS TWC wrote it up.

Long term drought conditions continued in August although minor improvement due to beneficial monsoon rain, occurred across parts of Cochise, Graham and Greenlee Counties.

What forecasters said that day

The local office's own words before the first event, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.

NWS Tucson, AZ wrote its last area forecast discussion before the first event at Jul 31, 9:50 PM MST, 2 hours 10 minutes earlier.

Area forecast discussion, Jul 31, 9:50 PM MST, 2 hours 10 minutes before

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TUCSON AZ
950 PM MST SUN JUL 31 2011

.SYNOPSIS...A FEW WEAK DISTURBANCES WILL INTERACT WITH MOISTURE IN
PLACE FOR A CHANCE OF MAINLY AFTERNOON AND EVENING THUNDERSTORMS
THROUGH MONDAY. THEREAFTER...SLIGHTLY DRIER AIR WILL SPREAD INTO THE
REGION FOR DECREASING CHANCES OF THUNDERSTORMS WEDNESDAY INTO AT
LEAST FRIDAY. THIS DRIER AIR WILL ALSO RESULT IN HOTTER AFTERNOON
TEMPERATURES WITH HIGHS PEAKING AROUND WEDNESDAY OR THURSDAY.

&&

.DISCUSSION...IT HAS BEEN A MODERATELY ACTIVE NIGHT ACROSS ALL OF
SOUTHEAST ARIZONA AS WIDESPREAD SHOWERS AND THUNDERSTORMS PRODUCED
SEVERAL AREAS RECEIVED HEAVY RAINFALL. INITIALLY...STORMS FORMED OFF
A BOUNDARY EXTENDING FROM WESTERN TUCSON TO THE SOUTH. THIS BOUNDARY
RESULTED IN A HEAVY RAIN AND A FEW SEVERE STORMS...AND MOVED MAINLY
NORTHWEST IN THE UPPER FLOW AS THE EVENING PROGRESSED.

IN ADDITION...A STRONG UPPER LOW MAKING ITS WAY THROUGH CHIHUAHUA
MEXICO THIS EVENING WAS ABLE TO ENHANCE STORMS OUT AHEAD OF IT AS IT
MOVED CLOSER TO OUR NECK OF THE WOODS. WE SAW A NICE COMPLEX BEGIN
OVER THE EXTREME SOUTHEAST CORNER OF COCHISE COUNTY AROUND 5 PM
TODAY...WITH SHOWERS BECOMING MORE NUMEROUS THRU THE EVENING HOURS
AS IT EXPANDED ACROSS THE REST OF COCHISE...EASTERN SANTA CRUZ
EASTERN PIMA...EASTERN PINAL...SOUTHERN GRAHAM AND SOUTHERN
GREENLEE COUNTIES.

OTHERWISE...AN APPARENT MCV OR MID-LEVEL SWIRL SEEN ON THE LOOP OF
THE KEMX RADAR IMAGERY IN SOUTHERN COCHISE COUNTY WILL ROTATE
NORTHWEST INTO WESTERN COCHISE COUNTY...AND THEN GET CAUGHT UP IN
THE UPPER FLOW AND TRACK NORTH NORTHEAST. THIS WILL TAKE THE
WIDESPREAD LIGHT TO MODERATE PRECIPITATION A LITTLE FARTHER
WEST...POSSIBLY INTO THE TUCSON METRO AREA...BEFORE TRACKING IT UP
THROUGH GRAHAM AND GREENLEE COUNTIES. THE LARGE COMPLEX OR MCS IN
SONORA MEXICO WILL CONTINUE TO WEAKEN AND IT TOO MAY TRACK NORTH
INTO THE DESERTS TO THE WEST OF TUCSON OVERNIGHT. THIS PRECIPITATION
WILL BE LIGHT...BUT WILL NECESSITATE IN ELEVATED POPS OUT IN THE
WESTERN DESERTS OVERNIGHT.

&&

.PREV DISCUSSION...THIS MORNINGS KTWC SOUNDING SHOWED A CONTINUED
MOIST AIRMASS IN PLACE WITH A PRECIPITABLE WATER VALUE OF 1.55
INCHES. IN ADDITION...THE AIRMASS IS MORE UNSTABLE TODAY THAN
YESTERDAY. MODIFYING THE SOUNDING USING T=99;TD=60 YIELDS A LIFTED
INDEX OF MINUS 5 AND A CAPE OF AROUND 1700 J/KG. THERE IS ALSO A
DECENT AMOUNT OF BOTH DIRECTIONAL AND SPEED SHEAR IN THE MID LEVELS
NOTED ON THE 12Z SOUNDING...SO THE STORMS THAT DEVELOP TODAY SHOULD
BE BETTER ORGANIZED. THE ONE DOWN SIDE IS THAT THE UPPER LEVEL FLOW
IS SUCH THAT THE ANVILS FROM THUNDERSTORMS WILL BLOW OUT AHEAD OF
THE STORMS AND COULD LIMIT INSOLATION OUT AHEAD OF THE STORMS.

THE MOST RECENT RADAR LOOP SHOWS SHOWER AND THUNDERSTORM ACTIVITY
CURRENTLY CONCENTRATED TO THE SOUTH AND SOUTHWEST OF THE TUCSON AREA
AND ALSO OVER THE WHITE MOUNTAINS OF GRAHAM AND GREENLEE COUNTIES.
ELSEWHERE...ISOLATED SHOWERS AND THUNDERSTORMS ARE OCCURRING. ALL OF
THE ACTIVITY IS MOVING TO THE NORTH NORTHWEST.

WATER VAPOR IMAGERY SHOWS A LARGE HIGH CENTERED OVER THE CENTRAL AND
SOUTHERN PLAINS WITH ARIZONA ON THE WESTERN PERIPHERY OF THIS HIGH.
THIS IS RESULTING IN SOUTHERLY FLOW IN MUCH OF THE COLUMN AS NOTED
ON THIS MORNING SOUNDING. A WEAK DISTURBANCE IS MOVING NORTHWARD
ACROSS PORTIONS OF BAJA AND THIS IS CONTINUING TO SPARK STORMS OVER
SOUTHERN CALIFORNIA AND INTO SRN NEVADA AS SEEN IN IR IMAGERY AND
RECENT RADAR MOSAIC LOOP. CLOSER TO HOME...A WEAK DISTURBANCE IS
OVER SE COLORADO WITH A COUPLE OF DISTURBANCES SOUTH OF THE BORDER
THAT WILL ENHANCE THUNDERSTORM CHANCES FOR THE REMAINDER OF THIS
AFTERNOON AND INTO TONIGHT. THE FIRST IS CURRENTLY GENERATING
SCATTERED CONVECTION OVER NORTH CENTRAL SONORA AND INTO SANTA CRUZ
AND SOUTHEAST PIMA COUNTY. ANOTHER DISTURBANCE (THE REMNANTS OF DON)
IS CURRENTLY MOVING THROUGH EASTERN CHIHUAHUA MEXICO HAS TRIGGERED A
CLUSTER OF THUNDERSTORMS OVER WESTERN CHIHUAHUA AND NORTHEAST SONORA
OVER THE SIERRA MADRES OCCIDENTALS. THESE STORMS WILL LIKELY DEVELOP
INTO A MCS LATE THIS AFTERNOON AND INTO THE EVENING HOURS WITH THE
MODELS SUGGESTING LINGERING OVERNIGHT CONVECTION SPREADING NORTHWARD
INTO SOUTHERN ARIZONA. I INCREASED RAIN CHANCES OVERNIGHT FROM THE
POP GRIDS THAT I INHERITED. IF IT TURNS OUT THAT THE MODELS ARE TOO
AGGRESSIVE IN THIS SOLUTION AND MY POPS ARE TOO HIGH THE EVENING
SHIFT CAN ALWAYS ADJUST POPS ACCORDINGLY.

MODELS SUGGEST A DOWNWARD TREND IN ACTIVITY BEGINNING ON MONDAY...
BUT ESPECIALLY BY WEDNESDAY AS THE RELATIVELY DRIER AIR BEHIND THE
REMNANTS OF DON OVER MUCH OF NORTHEAST MEXICO AND EXTREME SOUTHERN
TEXAS MAKES ITS WAY TOWARD THE DESERT SOUTHWEST. AT THE SAME TIME...
DRIER AIR FROM THE NORTHWEST THAT IS ASSOCIATED WITH A PACIFIC
TROUGH WILL TRY TO WORK ITS WAY INTO WESTERN ARIZONA. AS A RESULT...
THUNDERSTORM CHANCES WILL BE IN THE ISOLATED TO SCATTERED CATEGORY
MAINLY FOR CENTRAL AND EASTERN ZONES FOR WEDNESDAY THROUGH FRIDAY
WITH A SLIGHT UPSWING IN ACTIVITY MAINLY FOR THE MOUNTAINS LATE IN
THE WEEKEND.

HIGHS WILL BE NEAR NORMAL ON MONDAY...THEN 2 TO 5 DEGS ABOVE NORMAL
THROUGH THE WEEKEND...BUT THE WARMEST DAYS WILL BE WEDNESDAY AND
THURSDAY. LOWS WILL GENERALLY BE 4 TO 6 DEGS ABOVE NORMAL EACH DAY.

&&

.AVIATION...SCT-BKN CLOUD BASES AT 10-15K FT AGL THRU 14Z MON.
THROUGH 10Z MON...EXPECT -SHRA WITH ISOLD -TSRA WITH CLOUD BASES
6-8K FT AGL...EXPECT MVFR CONDITIONS WITH MTNS OBSCD AND PK WND TO
30 KTS IN -TSRA. SFC WND MAINLY LESS THAN 10 KTS THRU 18Z MON.
AVIATION DISCUSSION NOT UPDATED FOR TAF AMENDMENTS.

&&

.FIRE WEATHER...MOISTURE REMAINED IN PLACE FOR A CHANCE OF MAINLY
AFTERNOON AND EVENING SHOWERS AND THUNDERSTORMS AGAIN ON MONDAY.
THEREAFTER...NUMERICAL MODELS CONTINUED TO SHOW SOME DRIER AIR
MOVING INTO THE REGION WHICH WILL TRANSLATE TO DECREASING CHANCES OF
RAINFALL. THIS DRIER AIR WILL ALSO RESULT IN HOTTER AFTERNOON
TEMPERATURES WITH HIGHS PEAKING AROUND WEDNESDAY OR THURSDAY. EXPECT
NORMAL DIURNAL SURFACE WIND CHANGES AND...AS ALWAYS...STRONG AND
GUSTY WINDS CAN BE ANTICIPATED NEAR THUNDERSTORMS.

&&

.TWC WATCHES/WARNINGS/ADVISORIES...NONE.

WEATHER.GOV/TUCSON

Hazardous weather outlook, Jul 31, 10:30 AM MST, 13 hours 30 minutes before

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE TUCSON AZ
1030 AM MST SUN JUL 31 2011

AZZ501>515-011730-
WESTERN PIMA COUNTY-TOHONO O'ODHAM NATION-
UPPER SANTA CRUZ RIVER VALLEY/ALTAR VALLEY-TUCSON METRO AREA-
SOUTH CENTRAL PINAL COUNTY-SOUTHEAST PINAL COUNTY-
UPPER SAN PEDRO RIVER VALLEY-
EASTERN COCHISE COUNTY BELOW 5000 FEET-UPPER GILA RIVER VALLEY-
WHITE MOUNTAINS OF GRAHAM AND GREENLEE COUNTIES-
GALIURO AND PINALENO MOUNTAINS-CHIRICAHUA MOUNTAINS-
DRAGOON AND MULE AND HUACHUCA AND SANTA RITA MOUNTAINS-
CATALINA AND RINCON MOUNTAINS-BABOQUIVARI MOUNTAINS-
1030 AM MST SUN JUL 31 2011

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF SOUTHEAST
ARIZONA.

.DAY ONE...TODAY AND TONIGHT

EXPECT AN ACTIVE PERIOD OF SHOWERS AND THUNDERSTORMS TODAY AND
TONIGHT. SOME STORMS WILL GENERATE STRONG GUSTY WINDS AND HEAVY
RAINFALL. EVEN MODERATE RAIN MAY RESULT IN FLASH FLOODING NEAR AND
DOWNSTREAM OF THE WILDFIRE BURN SCARS.

.DAYS TWO THROUGH SEVEN...MONDAY THROUGH SATURDAY

AN UPSWING IN THUNDERSTORM ACTIVITY WILL CONTINUE INTO EARLY NEXT
WEEK. SOME STORMS WILL GENERATE STRONG GUSTY WINDS AND HEAVY
RAINFALL. EVEN MODERATE RAIN MAY RESULT IN FLASH FLOODING NEAR
AND DOWNSTREAM OF THE WILDFIRE BURN SCARS.

.SPOTTER INFORMATION STATEMENT...

WEATHER SPOTTERS ARE ENCOURAGED TO REPORT SIGNIFICANT WEATHER
CONDITIONS ACCORDING TO STANDARD OPERATING PROCEDURES.

WEATHER.GOV/TUCSON

In the hours before

Local storm report, Jul 31, 7:36 PM MST, 4 hours 24 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE TUCSON AZ
736 PM MST SUN JUL 31 2011

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0730 PM     TSTM WND DMG     SELLS                   31.92N 111.88W
07/31/2011                   PIMA               AZ   EMERGENCY MNGR

            FOUR TRANSMISSION LINES FOR POWER KNOCKED DOWN IN THE
            NORTHERN TOHONO OODHAM NATION AND HAS RESULTED TO LOSS
            OF POWER TO MAJORITY OF THE NATION.

&&

EVENT NUMBER TWC1100065

CWR

The radar

The national radar mosaic for the moment the first event began.

Open the radar archive at this moment

Event by event

14 drought. Local standard time, as filed.

Drought, Tohono O Odham Nation

When: August 1, 12:00 AM MST to August 31, 11:59 PM MST
Where: Tohono O Odham Nation forecast zone
Reported by: Other Federal Agency
Coordinates: 32.501, -111.567 (the zone’s center; the record gives no point)

After beneficial rainfall in July and early August, the entire month of August ended with below normal rainfall except across parts of western Cochise County. The result was that D3 extreme drought conditions retreated eastward, completely exiting Santa Cruz County, by the middle of the month, but expanded even farther westward across Pima and Pinal Counties by the end of August. D4 exceptional drought conditions did show an overall decrease in state coverage from 4.83% to 1.35%, with only extreme eastern Cochise County, southern Greenlee County, and extreme southeast Graham County remaining in exceptional drought conditions in southeast Arizona. The most impacted watersheds during August were the San Simon watershed (2nd percentile for rainfall) and the Santa Cruz watershed (2nd percentile for rainfall), which received very little rainfall. July's rainfall brought an end to the fire season so many recreational areas were reopened in August. The state and federal forest services conducted large scale seeding operations across the burn scar areas attempting to mitigate the flash flooding concerns. Very few ranchers were still holding onto cattle, so agriculture impacts were somewhat lessened during the month. Cotton and vegetable crops were reported as being fair to excellent as irrigation was being maximized.

Drought, Upper Santa Cruz River and Altar Valleys

When: August 1, 12:00 AM MST to August 31, 11:59 PM MST
Where: Upper Santa Cruz River and Altar Valleys forecast zone
Reported by: Other Federal Agency
Coordinates: 31.812, -111.318 (the zone’s center; the record gives no point)

Drought, Tucson Metro Area

When: August 1, 12:00 AM MST to August 31, 11:59 PM MST
Where: Tucson Metro Area forecast zone
Reported by: Other Federal Agency
Coordinates: 32.097, -111.790 (the zone’s center; the record gives no point)

Drought, South Central Pinal County

When: August 1, 12:00 AM MST to August 31, 11:59 PM MST
Where: South Central Pinal County forecast zone
Reported by: Other Federal Agency
Coordinates: 32.904, -111.345 (the zone’s center; the record gives no point)

Drought, Southeast Pinal County

When: August 1, 12:00 AM MST to August 31, 11:59 PM MST
Where: Southeast Pinal County forecast zone
Reported by: Other Federal Agency
Coordinates: 32.904, -111.345 (the zone’s center; the record gives no point)

Drought, Upper San Pedro River Valley

When: August 1, 12:00 AM MST to August 31, 11:59 PM MST
Where: Upper San Pedro River Valley forecast zone
Reported by: Other Federal Agency
Coordinates: 32.109, -110.569 (the zone’s center; the record gives no point)

Drought, Eastern Cochise County Below 5000 Feet

When: August 1, 12:00 AM MST to August 31, 11:59 PM MST
Where: Eastern Cochise County Below 5000 Feet forecast zone
Reported by: Other Federal Agency
Coordinates: 31.880, -109.751 (the zone’s center; the record gives no point)

Drought, Upper Gila River and Aravaipa Valleys

When: August 1, 12:00 AM MST to August 31, 11:59 PM MST
Where: Upper Gila River and Aravaipa Valleys forecast zone
Reported by: Other Federal Agency
Coordinates: 33.074, -109.563 (the zone’s center; the record gives no point)

Drought, White Mountains of Graham and Greenlee Counties

When: August 1, 12:00 AM MST to August 31, 11:59 PM MST
Where: White Mountains of Graham and Greenlee Counties forecast zone
Reported by: Other Federal Agency
Coordinates: 33.074, -109.563 (the zone’s center; the record gives no point)

Drought, Galiuro and Pinaleno Mountains

When: August 1, 12:00 AM MST to August 31, 11:59 PM MST
Where: Galiuro and Pinaleno Mountains forecast zone
Reported by: Other Federal Agency
Coordinates: 32.572, -110.328 (the zone’s center; the record gives no point)

Drought, Chiricahua Mountains

When: August 1, 12:00 AM MST to August 31, 11:59 PM MST
Where: Chiricahua Mountains forecast zone
Reported by: Other Federal Agency
Coordinates: 31.880, -109.751 (the zone’s center; the record gives no point)

Drought, Dragoon/Mule/Huachuca and Santa Rita Mountains

When: August 1, 12:00 AM MST to August 31, 11:59 PM MST
Where: Dragoon/Mule/Huachuca and Santa Rita Mountains forecast zone
Reported by: Other Federal Agency
Coordinates: 31.834, -110.796 (the zone’s center; the record gives no point)

Drought, Santa Catalina and Rincon Mountains

When: August 1, 12:00 AM MST to August 31, 11:59 PM MST
Where: Santa Catalina and Rincon Mountains forecast zone
Reported by: Other Federal Agency
Coordinates: 32.501, -111.567 (the zone’s center; the record gives no point)

Drought, Baboquivari Mountains

When: August 1, 12:00 AM MST to August 31, 11:59 PM MST
Where: Baboquivari Mountains forecast zone
Reported by: Other Federal Agency
Coordinates: 32.097, -111.790 (the zone’s center; the record gives no point)

What these are

Drought: A drought reaching severe (D2) or worse on the US Drought Monitor, or with notable impacts.

After NWS Directive 10-1605, the rules offices file Storm Data by.

The same day elsewhere

Every storm in Arizona in 2011 Every state in 2011 This day in weather history Warnings in Arizona, August 2011

Sources

NOAA National Centers for Environmental Information, Storm Events Database, compiled from the National Weather Service’s monthly Storm Data. Complete through 2026-06; NCEI adds each month about 75 days after it ends and revises past years a few times a year. Rebuilt 2026-09-24. Each event’s entry at NCEI: 345408, 345643, 345644, 345645, 345646, 345647, 345650, 345651, 345652, 345653, 345654, 345655, 345656, 345657.