Thunderstorms with heavy rain caused flash flooding in the Wallow Burn area near Nutrioso.
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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 with heavy rain caused flash flooding in the Wallow Burn area near Nutrioso.
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 18, 9:30 AM MST, 1 hour 30 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE FLAGSTAFF AZ 930 AM MST THU AUG 18 2011 .SYNOPSIS...EXPECT GOOD CHANCES FOR THUNDERSTORMS TODAY AND FRIDAY ...ESPECIALLY ALONG THE MOGOLLON RIM AND IN THE WHITE MOUNTAINS. ON SATURDAY...A DRIER SOUTHWESTERLY FLOW WILL WORK INTO WESTERN ARIZONA AND SPREAD EASTWARD ON SUNDAY. CHANCES FOR SHOWERS AND STORMS WILL DECREASE FROM SUNDAY INTO THE FIRST HALF OF NEXT WEEK. && .DISCUSSION...THIS MORNINGS SURFACE DEW POINTS HAVE RISEN COMPARED TO THIS TIME YESTERDAY WITH THE DEW POINTS AT THE PAGE AIRPORT INCREASING BY 15 DEGREES. THIS MEANS THE DEEPER MONSOON MOISTURE HAS REACHED THE UTAH BORDER AS INDICATED YESTERDAY BY THE FORECAST GUIDANCE. THE FLAGSTAFF 12Z SOUNDING ALSO SHOWS A MORE UNSTABLE MID LEVEL AIR MASS WHICH WILL INCREASE COVERAGE OF SHOWERS AND THUNDERSTORMS TODAY AS COMPARED TO WEDNESDAY. MORNING FORECAST GRIDS LOOK GOOD...NO UPDATES NEEDED. && .PREVIOUS DISCUSSION... SURFACE OBSERVATIONS AND SATELLITE PW ESTIMATES SHOW MONSOON MOISTURE HAS SPREAD NORTHWARD TO THE UTAH BORDER. WHILE THERE IS A FAIR AMOUNT OF DEBRIS CLOUDS ACROSS EASTERN AZ THIS MORNING...IT IS THINNING WITH TIME. MODELS SHOW GOOD INSTABILITY ACROSS THE NORTHLAND TODAY AND FRIDAY AND THUS EXPECT SCATTERED TO NUMEROUS SHOWERS AND THUNDERSTORMS ACROSS THE FORECAST AREA. FOR THE WEEKEND INTO NEXT WEEK...PROGS CONTINUE TO SHOW A CUT OFF LOW OVER CALIFORNIA...WITH A DRIER SOUTHWEST FLOW RETURNING TO WESTERN ARIZONA. PROGS SHOW MOISTURE AMOUNTS DECREASING FROM WEST TO EAST OVER THE WEEKEND. IN FACT THE GFS SHOWS A STABLE AIRMASS OVER ALL THE NORTHLAND AS EARLY AS SUNDAY. AT THIS TIME WE HAVE KEPT NEAR CLIMO POPS OVER THE EASTERN MOGOLLON RIM AND WHITE MOUNTAINS AND SLASHED THEM LIKE PRICES AT A FURNITURE STORE TO SLIGHT CHANCE (10% -20%) ELSEWHERE. SHOULD GFS TRENDS CONTINUE...MOST OF THE NORTHLAND WOULD BE DRY FROM SUNDAY THROUGH WEDNESDAY. && .AVIATION...FOR THE 18Z PACKAGE...EXPECT SCATTERED SHRA/TSRA TO DEVELOP ACROSS NORTHERN WITH THE MOST NUMEROUS COVERAGE OVER THE EASTERN MOGOLLON RIM AND WHITE MTNS. ERRATIC AND GUSTY OUTFLOW WINDS AND BRIEF MVFR TO LCL IFR CONDITIONS ARE POSSIBLE IN THE HEAVIER SHOWERS AND THUNDERSTORMS. STORMS WILL DIMINISH IN COVERAGE...BECOMING MORE ISOLATED AFTER 03Z. AVIATION DISCUSSION NOT UPDATED FOR AMENDMENTS. && .FGZ WATCHES/WARNINGS/ADVISORIES...NONE. && PUBLIC........BOHLIN / DL AVIATION......GH FOR NORTHERN ARIZONA WEATHER INFORMATION VISIT WEATHER.GOV/FLAGSTAFF.
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE FLAGSTAFF AZ 600 AM MST THU AUG 18 2011 AZZ004>018-037>040-190645- KAIBAB PLATEAU-MARBLE AND GLEN CANYONS-GRAND CANYON COUNTRY- COCONINO PLATEAU-YAVAPAI COUNTY MOUNTAINS- NORTHEAST PLATEAUS AND MESAS HWY 264 NORTHWARD-CHINLE VALLEY- CHUSKA MOUNTAINS AND DEFIANCE PLATEAU- LITTLE COLORADO RIVER VALLEY IN COCONINO COUNTY- LITTLE COLORADO RIVER VALLEY IN NAVAJO COUNTY- LITTLE COLORADO RIVER VALLEY IN APACHE COUNTY- WESTERN MOGOLLON RIM-EASTERN MOGOLLON RIM-WHITE MOUNTAINS- NORTHERN GILA COUNTY-YAVAPAI COUNTY VALLEYS AND BASINS- OAK CREEK AND SYCAMORE CANYONS-BLACK MESA AREA- NORTHEAST PLATEAUS AND MESAS SOUTH OF HWY 264- 600 AM MST THU AUG 18 2011 THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF EAST CENTRAL ARIZONA...NORTH CENTRAL ARIZONA...NORTHEAST ARIZONA AND WEST CENTRAL ARIZONA. .DAY ONE...TODAY AND TONIGHT SCATTERED TO NUMEROUS AFTERNOON AND EVENING THUNDERSTORMS ARE EXPECTED TODAY ACROSS NORTHERN ARIZONA. THE GREATEST STORM COVERAGE IS EXPECTED IN THE WHITE MOUNTAINS. LIGHTNING...LOCALLY HEAVY RAINFALL AND FLOODING WILL BE THE MAIN THREATS. .DAYS TWO THROUGH SEVEN...FRIDAY THROUGH WEDNESDAY SCATTERED TO NUMEROUS SHOWERS AND THUNDERSTORMS ARE FORECAST FRIDAY. FOR THE WEEKEND INTO EARLY NEXT WEEK...A DRIER SOUTHWEST FLOW IS EXPECTED TO AFFECT CENTRAL AND WESTERN PORTIONS OF THE STATE...WITH THE BEST CHANCE OF THUNDERSTORMS SHIFTING INTO EASTERN ARIZONA. .SPOTTER INFORMATION STATEMENT. WEATHER SPOTTERS SHOULD REPORT SIGNIFICANT WEATHER CONDITIONS ACCORDING TO STANDARD OPERATING PROCEDURES.
The Flagstaff radar (KFSX), 171 km away, was scanning. The volume nearest the first event began at 18:01 UTC.
2 flash flood. Local standard time, as filed.
Flash flooding flooding and debris flows were reported along side canyons and over road ways in the eastern side of Greer. Rocks one foot in diameter washed over roads. The creek in Butler Canyon over flowed its banks.
Flash flooding was reported in Nutrioso with sheet flow over fields on the east side of town. Nutrioso Creek was running bank full with black water (ash) and debris. Over an inch and a half (1.60 inches) of rain fell between 11 AM and Noon.
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: 341907, 341908.