Thunderstorms produced heavy rain over the Wallow Burn Area causing flash flooding and debris/mud flows.
Every event with a place to put it. Tap one for its entry below.
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.
The episode as NWS FGZ wrote it up.
Thunderstorms produced heavy rain over the Wallow Burn Area causing flash flooding and debris/mud flows.
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 Flagstaff, AZ wrote its last area forecast discussion before the first event at Aug 21, 9:15 AM MST, 1 hour 25 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE FLAGSTAFF AZ 915 AM MST SUN AUG 21 2011 .SYNOPSIS...FOR THE NEXT FEW DAYS...DRIER SOUTHWEST FLOW WILL KEEP THUNDERSTORM ACTIVITY ACROSS THE WESTERN AND CENTRAL PORTIONS OF ARIZONA TO A MINIMUM. HOWEVER...MUCH OF THE EASTERN THIRD OF THE REGION WILL CONTINUE TO SEE DAILY THUNDERSTORM CHANCES. MOISTURE WILL BEGIN TO INCREASE AGAIN ACROSS MUCH OF THE STATE BY THE END OF THIS COMING WEEK. && .DISCUSSION...NO MAJOR UPDATES MADE THIS MORNING. DRIER AIR ACROSS WESTERN AZ WILL LIMIT THUNDERSTORM CHANCES GENERALLY WEST OF FLAGSTAFF TODAY AS REFLECTED WELL IN THE FORECAST. EASTERN AZ...ESPECIALLY THE EASTERN MOGOLLON RIM AND WHITE MTNS...WILL STILL SEE SCATTERED THUNDERSTORMS DEVELOP THIS AFTERNOON AND EVENING. STORMS THAT DO DEVELOP WILL BE CAPABLE OF PRODUCING LOCALLY HEAVY RAINFALL. && .PREVIOUS DISCUSSION (325 AM)...DRIER CONDITIONS AND WARMER TEMPERATURES ALOFT WILL LIMIT CONVECTION OVER THE CENTRAL AND WESTERN PORTIONS OF THE STATE THROUGH MUCH OF THE WEEK. THE BEST CHANCES FOR CONVECTION WILL BE WELL EAST OF FLAGSTAFF...NEAR THE NEW MEXICO BORDER. EVEN WHEN DEEPER SOUTHERLY FLOW RETURNS BY MID-WEEK...WARM TEMPERATURES ALOFT WILL SERVE AS A CAP FOR MUCH OF THE AREA. CORRESPONDINGLY...SURFACE TEMPERATURES WILL CLIMB EACH DAY...WITH LIGHT BREEZES DEVELOPING. BY LATE IN THE WEEK AND NEXT WEEKEND...HGHTS WILL FALL SLIGHTLY AS A TROUGH MOVES BY TO THE NORTH. THIS SHOULD OPEN THE DOOR FOR INCREASING CHANCES FOR SHOWERS AND THUNDERSTORMS. && .AVIATION...FOR THE 18Z PACKAGE...SCATTERED SHOWERS AND THUNDERSTORMS WILL DEVELOP...MOST NUMEROUS EAST OF A KPAN-KINW-K0V7 LINE AND ISOLD TO WDLY SCT WEST/NORTHWEST OF THAT LINE. MVFR/IFR CONDITIONS WILL BE POSSIBLE IN THE STRONGER STORMS. AFTER 02Z...SHOWERS AND THUNDERSTORMS WILL DECREASE IN COVERAGE AND INTENSITY WITH ISOLD -SHRA/-TSRA EAST OF THE LINE WITH CLEARING WEST OF THE LINE. AVIATION DISCUSSION NOT UPDATED FOR AMENDMENTS. && .FGZ WATCHES/WARNINGS/ADVISORIES...NONE. && PUBLIC........MCS/PETERSON AVIATION......TC FOR NORTHERN ARIZONA WEATHER INFORMATION VISIT WEATHER.GOV/FLAGSTAFF.
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE FLAGSTAFF AZ 635 AM MST SUN AUG 21 2011 AZZ004>018-037>040-220700- WESTERN MOGOLLON RIM-GRAND CANYON COUNTRY-YAVAPAI COUNTY MOUNTAINS- YAVAPAI COUNTY VALLEYS AND BASINS-OAK CREEK AND SYCAMORE CANYONS- MARBLE AND GLEN CANYONS-KAIBAB PLATEAU-COCONINO PLATEAU- NORTHEAST PLATEAU AND MESAS HWY 264 NORTHWARD- NORTHEAST PLATEAU AND MESAS SOUTH OF HWY 264- CHINLE VALLEY-CHUSKA MOUNTAINS AND DEFIANCE PLATEAU- BLACK MESA AREA-LITTLE COLORADO RIVER VALLEY IN COCONINO COUNTY- LITTLE COLORADO RIVER VALLEY IN NAVAJO COUNTY- LITTLE COLORADO RIVER VALLEY IN APACHE COUNTY- EASTERN MOGOLLON RIM-WHITE MOUNTAINS-NORTHERN GILA COUNTY- 635 AM MST SUN AUG 21 2011 THIS HAZARDOUS WEATHER OUTLOOK IS FOR APACHE...COCONINO...NORTHERN GILA...NAVAJO...AND YAVAPAI COUNTIES IN NORTHERN ARIZONA. .DAY ONE...TODAY DRIER AIR AND RELATIVELY WEAK INSTABILITY IN THE ATMOSPHERE WILL LIMIT THUNDERSTORM DEVELOPMENT TODAY. MUCH OF THE CENTRAL AND WESTERN PORTIONS OF OUR REGION WILL SEE ONLY ISOLATED...OR NO STORM ACTIVITY...WHILE THE EASTERN PORTIONS WILL SEE SCATTERED SHOWERS AND THUNDERSTORMS. THE MAIN THREATS FROM ANY STORMS TODAY WILL BE BRIEF HEAVY RAIN AND SMALL HAIL. THE WALLOW AND LOCUST BURN AREAS HAVE A MODERATE RISK OF FLOODING FROM RAINFALL...WHILE THE SCHULTZ BURN AREA HAS A LOW RISK DUE TO THE DRIER AIR TODAY. .DAYS TWO THROUGH SEVEN...MONDAY THROUGH SATURDAY MOST STORM ACTIVITY WILL STAY EAST OF FLAGSTAFF TOWARD THE NEW MEXICO BORDER THROUGH MID-WEEK. INCREASING SOUTHERLY FLOW TOWARD THE END OF THE WEEK WILL SLOWLY BRING THUNDERSTORMS BACK NORTH AND WEST BY NEXT WEEKEND. .SPOTTER INFORMATION STATEMENT... WEATHER SPOTTERS ARE ENCOURAGED TO REPORT SIGNIFICANT WEATHER CONDITIONS ACCORDING TO STANDARD OPERATING PROCEDURES.
The Flagstaff radar (KFSX), 172 km away, was scanning. The volume nearest the first event began at 17:38 UTC.
2 flash flood, 1 heavy rain. Local standard time, as filed.
A business in Greer reported heavy rain (0.50) with water flowing down the street. A Mesonet station at Hay Lake recorded 0.87 inches of rain.
Heavy rain from a thunderstorm over the Wallow Burn area caused flash flooding, debris flows, and mud flows across Highway 180 about a mile north of Nutrioso. There was a motorcycle accident due to the mud on the roadway.
A foot of water was running down Butler Canyon which is normally dry.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Arizona in 2011Every state in 2011This day in weather historyWarnings in Arizona, August 2011
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: 343488, 343521, 343493.