Subtropical moisture under a southwest flow aloft resulted in some thunderstorms with heavy rainfall in southeast Utah.
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.
Subtropical moisture under a southwest flow aloft resulted in some thunderstorms with heavy rainfall in southeast Utah.
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 Jul 20, 2:08 PM MST, 5 hours 22 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GRAND JUNCTION CO 308 PM MDT WED JUL 20 2011 .SHORT TERM...TONIGHT THROUGH FRIDAY... THUNDERSTORMS BEGAN TO FIRE OVER THE TAVAPUTS/ROAN PLATEAU AND FLATTOPS IN THE NORTH...THE GRAND MESA IN CENTRAL CO...AND THE SAN JUAN MTS TO THE SOUTH. THUS FAR THE CONVECTION HAS BEEN RUN OF THE MILL...BUT BELIEVE THIS WILL NOT HOLD. PRECIPITABLE WATER ON THE GJT SOUNDING THIS MORNING WAS AT 0.96 IN. WITH PLENTY OF CAPE. NAM12 FORECAST SOUNDINGS ACROSS THE AREA SHOW SIMILAR CONDITIONS SOUTH OF THE BOOKCLIFFS AND TAVAPUTS...WITH DRIER CONDITIONS TO THE NORTH. A MIDLEVEL CAP AT 20K FT SHOULD HOLD BACK CONVECTION UNTIL THAT BREAKS...WHICH SHOULD HAPPEN ABOUT 330-400 PM. SMALL HAIL WAS REPORTED FROM A STORM NEAR MONTICELLO EARLIER TODAY...SO IT APPEARS HAIL PRODUCTION MAY BE MORE POSSIBLE TODAY AND TONIGHT. THE MONSOON PLUME HAS DEFINITELY LAID OVER TO THE NE...WITH MUCH DRIER AIR MOVING IN OVER EASTERN UT AND NW CO. PRECIPITABLE WATER IN THE SLC SOUNDING WAS 1/2 THAT IN THE GJT SOUNDING...SO BELIEVE THE CURRENT DRYING TREND WILL CONTINUE FROM NORTHWEST TO SOUTHEAST TONIGHT THROUGH FRIDAY. AFTER INCREASING STORM COVERAGE AND CLOUD COVER FOR THIS AFTERNOON AND EVENING...HAVE DECREASED IT FOR LATE TONIGHT...AND THURSDAY THRU FRIDAY. IN GENERAL THE DRYING TREND WILL BRING TEMPERATURES BACK TO NORMAL AND SLIGHTLY ABOVE NORMAL THU AND FRI. .LONG TERM...SATURDAY THROUGH TUESDAY... NO SIGNIFICANT CHANGES SEEN IN THE MIDRANGE MODELS FOR THE EXTENDED TIME PERIOD. HIGH PRESSURE WILL BE CENTERED OVER THE GREAT PLAINS WITH BROAD LOW PRESSURE OVER THE WEST COAST. FLOW AROUND THE HIGH WILL EDGE THE MONSOON PLUME A BIT FURTHER WEST AND NORTH SAT AND SUNDAY OVER THE SAN JUANS AND PORTIONS OF THE CO CENTRAL MOUNTAINS AND SE UT...SO THE CHC OF THUNDERSTORMS WILL INCREASE IN THOSE AREAS. MONDAY AND TUESDAY SOLUTIONS SHOW THE MONSOON CURVING BACK OVER MUCH OF WESTERN CO AND SE UT. && .AVIATION... SCATTERED SHOWERS AND STORMS WILL CONTINUE THIS EVENING. STORMS WILL PRODUCE MVFR/ISOLD IFR CIGS AND VSBYS OVER THE MOUNTAINS. THUNDERSTORM DEVELOPMENT WILL DECREASE THURSDAY. && .GJT WATCHES/WARNINGS/ADVISORIES... CO...NONE. UT...NONE. && SHORT TERM......CJC LONG TERM.......CJC AVIATION........CJC
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE GRAND JUNCTION CO 545 AM MDT WED JUL 20 2011 COZ001>014-017>023-UTZ022>025-027>029-211200- 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- 545 AM MDT WED JUL 20 2011 THIS HAZARDOUS WEATHER OUTLOOK IS FOR EASTERN UTAH AND WESTERN COLORADO. .DAY ONE...TODAY AND TONIGHT... MONSOONAL MOISTURE WILL CONTINUE ACROSS THE FORECAST AREA. EXPECT SHOWER AND THUNDERSTORM ACTIVITY TO INCREASE DURING THE DAY AND CONTINUE INTO THE EVENING. LOCALLY HEAVY RAIN IS POSSIBLE WITH THESE STORMS. .DAYS TWO THROUGH SEVEN...THURSDAY THROUGH TUESDAY... A MODERATE MONSOONAL SURGE WILL OCCUR OVER THE SOUTH FRIDAY AND AGAIN SUNDAY...WITH INCREASING MOISTURE OVER MOST OF THE REGION SEEN EARLY NEXT WORK WEEK. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION IS NOT EXPECTED AT THIS TIME.
The Grand Junction radar (KGJX), 122 km away, was scanning. The volume nearest the first event began at 02:28 UTC.
1 flash flood. Local standard time, as filed.
Flash flood waters in Arches National Park were over a foot and a half deep across the Delicate Arch road which was closed for several hours until the water receded.
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, July 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: 331561.