Moist and unstable southerly flow led thunderstorm development with many areas receiving heavy rainfall and isolated severe wind gusts.
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 GJT wrote it up.
Moist and unstable southerly flow led thunderstorm development with many areas receiving heavy rainfall and isolated severe wind gusts.
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 Grand Junction, CO wrote its last area forecast discussion before the first event at Aug 3, 1:32 PM MST, 1 hour 21 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GRAND JUNCTION CO 232 PM MDT WED AUG 3 2011 .SHORT TERM DISCUSSION...TONIGHT THROUGH THURSDAY... STORMS THIS AFTERNOON ARE SHOWING ONLY SLOW MOTION TO THE NE FOR LOCALIZED POTENTIAL FOR FLOODING. IN SW FLOW ALOFT A DISTURBANCE IS WORKING NE THROUGH NE UTAH-EXTREME NW CO LATE THIS AFTERNOON WHERE STORMS WILL BE A BIT MORE ENHANCED AND NUMEROUS. THE HRRR INDICATES DYNAMICAL SUPPORT WILL BE LIFTING INTO SOUTHERN WYOMING BY 6 PM. STILL BOUNDARY INTERACTION WILL LIKELY GENERATE SOME NIGHTTIME STORMS. NO FAVORED LOCATION IS EVIDENT THIS AFTERNOON SO HAVE BLANKETED THE FORECAST AREA WITH ISOLATED POPS. THURSDAY...MOISTURE DIMINISHES SOMEWHAT BUT AFTERNOON HEATING WILL AGAIN GENERATE MAINLY MOUNTAIN CONVECTION. THE EMPHASIS SHIFTS SOUTH AS A DISTURBANCE...CURRENTLY IN SE ARIZONA...PASSES THROUGH THE SOUTHEAST PORTION OF OUR SAN JUAN MTNS INCLUDING DURANGO AND PAGOSA SPRINGS. .LONG TERM DISCUSSION...THURSDAY NIGHT THROUGH WEDNESDAY. THE DRYING TREND WILL BE UNDERWAY ON FRIDAY AS A WESTERLY FLOW ADVECTS DRIER AIR OVER THE REGION. ENOUGH MOISTURE WILL REMAIN OVER THE SOUTH AND EASTERN PORTION OF THE FORECAST AREA...FOR ANOTHER ROUND OF SCATTERED LATE-DAY THUNDERSTORMS. BUT COVERAGE SHOULD BE MARKEDLY LESS THAN WHAT WE HAVE SEEN LATELY. IN ADDITION...THE STRONGER FLOW OVER THE NORTH WILL MIX TO THE SURFACE FOR BREEZY CONDITIONS DURING THE AFTERNOON...MAINLY ALONG THE WY BORDER. THE DRYING TREND WILL THEN CONTINUE AS SHORTWAVE ENERGY CONTINUES TO MOVE INTO THE PACIFIC NORTHWEST THEN ACROSS THE NORTHERN TIER STATES. MODELS INDICATE THE WESTERLY FLOW WILL CONTINUE TO SUPPRESS THE SUB TROPICAL MOISTURE PLUME THROUGH THE REMAINDER OF THE PERIOD. THEREFORE LITTLE CHANGE IS EXPECTED FROM DAY TO DAY DURING THE NEW WEEK. THE DRIER CONDITIONS WILL RESULT IN LESS CLOUDS...AND THUS WARMER HIGH TEMPERATURES...AND COOLER NIGHTTIME LOWS. && .AVIATION... SCATTERED CONVECTION WILL AGAIN HUG THE HIGHER TERRAIN THROUGH THIS EVENING...ALTHOUGH SOME OF THESE STORMS WILL DRIFT OVER THE VALLEYS. BRIEF PERIODS OF MVFR CIG AND VIS WILL BE POSSIBLE AT THE MOUNTAIN AIRPORTS FROM PASSING STORMS AND HEAVY SHOWERS...BUT DESERT VALLEY AIRPORTS WILL LIKELY STAY VFR. CONVECTIVE ACTIVITY WILL DIMINISH BY MIDNIGHT...WITH A FEW NOCTURNAL STORMS POSSIBLE...MAINLY OVER THE SOUTHERN MOUNTAINS. ANOTHER ROUND OF CONVECTION IS SCHEDULED FOR THURSDAY AFTERNOON. && .GJT WATCHES/WARNINGS/ADVISORIES... CO...NONE. UT...NONE. && SHORT TERM...JOE LONG TERM....EH AVIATION.....TGJT
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE GRAND JUNCTION CO 600 AM MDT WED AUG 3 2011 COZ001>014-017>023-UTZ022>025-027>029-041200- ANIMAS RIVER BASIN-ARCHES/GRAND FLAT-CANYONLANDS/NATURAL BRIDGES- CENTRAL COLORADO RIVER BASIN- CENTRAL GUNNISON AND UNCOMPAHGRE RIVER BASIN- CENTRAL YAMPA RIVER BASIN-DEBEQUE TO SILT CORRIDOR- EASTERN UINTA BASIN-EASTERN UINTA MOUNTAINS- ELKHEAD AND PARK MOUNTAINS-FLAT TOPS- FOUR CORNERS/UPPER DOLORES RIVER- GORE AND ELK MOUNTAINS/CENTRAL MOUNTAINS-GRAND AND BATTLEMENT MESAS- GRAND VALLEY-LA SAL AND ABAJO MOUNTAINS-LOWER YAMPA RIVER BASIN- NORTHWEST SAN JUAN MOUNTAINS-PARADOX VALLEY/LOWER DOLORES RIVER- ROAN AND TAVAPUTS PLATEAUS-SAN JUAN RIVER BASIN-SOUTHEAST UTAH- SOUTHWEST SAN JUAN MOUNTAINS-TAVAPUTS PLATEAU- UNCOMPAHGRE PLATEAU AND DALLAS DIVIDE-UPPER GUNNISON RIVER VALLEY- UPPER YAMPA RIVER BASIN-WEST ELK AND SAWATCH MOUNTAINS- 600 AM MDT WED AUG 3 2011 THIS HAZARDOUS WEATHER OUTLOOK IS FOR EASTERN UTAH AND WESTERN COLORADO. .DAY ONE...TODAY AND TONIGHT... EXPECT SCATTERED AFTERNOON SHOWERS AND THUNDERSTORMS OVER THE MOUNTAINS AND NEAR THE HIGHER TERRAIN...A FEW OF THESE STORMS WILL DRIFT OVER THE VALLEYS LATE AFTERNOON AND EARLY EVENING. BRIEF HEAVY RAIN WILL ACCOMPANY THESE STORMS WITH LOCALIZED MUD DEBRIS FLOWS. STORMS WILL DIMINISH AFTER SUNSET. .DAYS TWO THROUGH SEVEN...THURSDAY THROUGH TUESDAY... THURSDAY...SCATTERED AFTERNOON AND EVENING SHOWERS AND THUNDERSTORMS WILL CONTINUE...PRIMARILY OVER THE MOUNTAINS AND NEAR HIGHER TERRAIN. BRIEF HEAVY RAINS HAVE THE POTENTIAL TO GENERATE MUD DEBRIS FLOWS ONTO ROADS AND RISES ALONG STREAMS AND NORMALLY DRY CREEK BEDS OR WASHES WILL BE POSSIBLE. FRIDAY AND SATURDAY...THE THREAT OF AFTERNOON AND EVENING THUNDERSTORMS DIMINISHES TO SLIGHT CHANCE. MOST STORMS WILL STAY CONFINED TO THE HIGHER TERRAIN. SUNDAY THROUGH TUESDAY...MOSTLY DRY CONDITIONS ARE EXPECTED AS THE MONSOONAL MOISTURE PLUME GETS SUPPRESSED OVER THE DESERT SOUTHWEST. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION IS NOT EXPECTED TONIGHT.
The Grand Junction radar (KGJX), 137 km away, was scanning. The volume nearest the first event began at 21:55 UTC.
1 thunderstorm wind. Local standard time, as filed.
Thunderstorm outflow winds of 59 mph were measured and Canyonlands Airport.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Utah in 2011Every state in 2011This day in weather historyWarnings in Utah, 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: 331793.