Strong thunderstorms in a moist airmass produced heavy rainfall along with some large hail.
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.
Strong thunderstorms in a moist airmass produced heavy rainfall along with some large hail.
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 4, 9:19 AM MST, 2 hours 50 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GRAND JUNCTION CO 1019 AM MDT WED AUG 4 2010 .UPDATE...GRIDS UPDATED ACROSS THE NORTH FOR THE LINE OF ACTIVE THUNDERSTORMS THIS MORNING. && .PREVIOUS DISCUSSION ISSUED 455 AM MDT WED AUG 4 2010... .SHORT TERM...TODAY THROUGH THURSDAY NIGHT... THE GENERAL PATTERN FEATURING HIGH PRESSURE OVER THE SOUTHERN PLAINS OF THE U.S. AND A SHALLOW TROUGH OF LOW PRESSURE ALONG THE WEST COAST REMAINED IN PLACE OVERNIGHT. THIS HAS ALLOWED THE MONSOONAL SURGE TO CONTINUE SWEEPING ACROSS THE REGION FROM THE SOUTH AND SOUTHWEST. A WEAK SHORTWAVE MOVING EASTWARD OVER THE KSBS AREA CONTINUED TO GENERATE SCATTERED SHOWERS AND EMBEDDED THUNDERSTORMS OVER THE NORTHERN MOUNTAINS EARLY THIS MORNING. EXPECT THIS ACTIVITY WILL HAVE MOVED EAST OF THE DIVIDE BY SUNRISE...SO WILL MAINTAIN ONLY SLIGHT CHANCES ACROSS THE AREA BEFORE NOON. MEANWHILE...TO THE WEST...A STRONGER DISTURBANCE WAS PROPAGATING NORTHEASTWARD ACROSS NORTHERN UTAH SUSTAINING AN AREA SCATTERED SHOWERS AND THUNDERSTORMS. MODELS INDICATED THIS DISTURBANCE WILL BRUSH THE NORTH DURING THE AFTERNOON WITH ADDITIONAL LIFT PROVIDED BY DIVERGENCE ALOFT ASSOCIATED WITH A JET STREAK MOVING THROUGH SOUTHERN WYOMING. THIS WILL UNDOUBTEDLY LEAD TO GREATER STORM COVERAGE ACROSS THE NORTH DURING THE AFTERNOON AND EVENING...AND POSSIBLY SOME STRONG STORMS. HOWEVER...DESPITE INCREASED MOISTURE... NOT OVERLY CONCERNED ABOUT THE POTENTIAL FOR FLASH FLOODING NORTH OF THE I-70 CORRIDOR. PW VALUES ARE PREDICTED TO REMAIN WELL BELOW 1 INCH...SOILS HAVE SEEN LESS RAINFALL...AND MODEL SOUNDINGS INDICATED STORMS MOTION OF AROUND 15 MPH FROM THE SOUTHWEST. IN CONTRAST...ACROSS THE SOUTH SOILS REMAINED SATURATED FROM DAYS OF REPEATED PERIODS OF HEAVY PRECIPITATION. MODELS INDICATED PW VALUES OVER ONE INCH WILL BE COMMON AND STEERING WINDS WILL ONLY MOVE STORMS AT ABOUT 5 MPH. THEREFORE...WILL HOIST ANOTHER WATCH FOR THE SOUTHERN HALF OF THE CWFA FOR THE AFTERNOON AND EVENING. GENERAL PATTERN CHANGES LITTLE ON THURSDAY...THOUGH A DEEPENING OF THE PACIFIC TROF WILL AMPLIFY THE RIDGE OVER THE REGION. THEREFORE ...FIND THE INDICATED DECREASE IN PW OVER THE AREA A BIT PUZZLING AND AM DUBIOUS OF THIS SOLUTION. THEREFORE...WILL CONTINUE FORECAST CALLING FOR SCATTERED TO NUMEROUS SHOWERS AND THUNDERSTORMS. THE POTENTIAL FOR WIDESPREAD HEAVY RAIN WOULD SEEM TO BE DIMINISHING IF MODELS ARE CORRECT SO WILL LET NEXT SHIFT DETERMINE WHETHER ADDITIONAL WATCH WARRANTED FOR THURSDAY. NEAR NORMAL TEMPERATURES OBSERVED ACROSS THE REGION YESTERDAY FOR THE MOST PART...AND DID NOT SEE ANY REASON TO MAKE SIGNIFICANT CHANGES TO NEAR PERSISTENCE FORECAST TODAY AND THURSDAY. .LONG TERM...FRIDAY THROUGH TUESDAY... SOME DRYING IS SEEN FRIDAY BUT MOISTURE REMAINS ADEQUATE FOR LIKELY POPS OVER THE SRN MTNS AND SCATTERED COVERAGE ELSEWHERE. OTHERWISE NO BIG CHANGES ARE SEEN AS TROF REMAINS ALONG THE WEST COAST WITH HIGH PRESSURE LOCATED OVER TX. THE SOUTHERN PORTION OF THE TROF OVER CA WORKS IT WAY INTO THE GRT BASIN SATURDAY ACCOMPANIED BY AN INCREASE IN PCP WTR. DUE TO INCREASING DYNAMICS AND SHEAR ENVIRONMENT EXPECT STORMS TO BE MORE ORGANIZED AND ENERGETIC. AS TROF RELOADS ALONG THE WEST COAST SUNDAY DRAMATIC DRYING TAKES PLACE OVER THE WRN PORTION OF OUR CWA. STILL BELIEVE MDLS MAY BE OVERDOING THIS TREND SO ONLY A SLIGHT DOWNWARD ADJUSTMENT TO POPS. DEEPEST MSTR WILL BE ALONG AND NEAR THE CONTINENTAL DIVIDE OR THE EASTERN PORTION OF OUR CWA. MONDAY-TUESDAY...GOOD MODEL AGREEMENT THAT A SIGNIFICANT EXTRA- TROPICAL WAVE WILL WORK FROM SW TO NE THROUGH THE EASTERN GREAT BASIN. THE EC IS SLOWER AND CLOSER TO THE TIMING ADVERTISED BY YESTERDAY/S GFS. TODAY/S GFS IS FASTER WITH THIS FEATURE. BOTH HAVE A WEAK COLD CORE FEATURE. WENT WITH THE SLOWER EC PASSING THE WAVE ON MONDAY. THIS COULD POTENTIALLY PRODUCE STRONGER STORMS WITH HAIL THREAT ACROSS NE UTAH AND FAR NW COLORADO. THEN DRIER AIR WORKS IN FROM THE W-NW BEHIND THIS FEATURE FOR A DOWNTURN OF POPS INTO THE NEW WEEK. && .AVIATION... EXPECT SCATTERED TO NUMEROUS SHOWERS AND THUNDERSTORMS...ESPECIALLY DURING THE AFTERNOON AND EVENING HOURS. GREATEST COVERAGE WILL BE SOUTH OF I-70. AREAS OF MVFR CEILINGS AND VISIBILITY IN HEAVY RAIN WILL RESULT IN MOUNTAIN OBSCURATIONS. POCKETS OF TORRENTIAL DOWNPOURS WILL RESULT IN IFR OR LIFR CEILINGS AND VISIBILITY. ADDITIONAL HAZARDS INCLUDE OUTFLOW WINDS TO 30 MPH AND SMALL HAIL. ACTIVITY WILL DECREASE OVERNIGHT WITH SIMILAR CONDITIONS EXPECTED THURSDAY. && .GJT WATCHES/WARNINGS/ADVISORIES... CO...NONE. UT...NONE. SHORT TERM.....NL LONG TERM......MC/JOE AVIATION.......TGJT
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE GRAND JUNCTION CO 755 AM MDT WED AUG 4 2010 COZ001>014-017>023-UTZ022>025-027>029-051340- 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- 755 AM MDT WED AUG 4 2010 ...FLASH FLOOD WATCH IN EFFECT FROM NOON THROUGH THIS EVENING FOR SOUTHEAST UTAH AND SOUTHWEST COLORADO... THIS HAZARDOUS WEATHER OUTLOOK IS FOR EASTERN UTAH AND WESTERN COLORADO. .DAY ONE...TODAY AND TONIGHT NUMEROUS SHOWERS AND THUNDERSTORMS ARE EXPECTED ACROSS MUCH OF WESTERN COLORADO AND EASTERN UTAH THIS AFTERNOON...CONTINUING WELL INTO THE NIGHT. THE STRONGEST THUNDERSTORMS WILL PRODUCE SMALL HAIL...GUSTY WINDS TO 30 MPH AND VERY HEAVY RAINFALL. HEAVY DOWNPOURS WILL LIKELY RESULT IN FLASH FLOODING ACROSS PORTIONS OF SOUTHEAST UTAH AND SOUTHWEST COLORADO...ESPECIALLY NEAR STEEP TERRAIN AND IN NARROW SLOT CANYONS. THEREFORE...A FLASH FLOOD WATCH WILL BE IN EFFECT FOR THESE AREAS THIS AFTERNOON AND EVENING. PLEASE SEE THE GRAND JUNCTION NATIONAL WEATHER SERVICE WEB SITE AT WEATHER.GOV/GJT FOR THE LATEST INFORMATION. .DAYS TWO THROUGH SEVEN...THURSDAY THROUGH TUESDAY SLIGHT DRYING IS EXPECTED THIS WEEKEND AND INTO THE NEXT WORK WEEK. WHILE THE CHANCE FOR LATE DAY SHOWERS AND THUNDERSTORM WILL PERSIST EACH DAY...LESS COVERAGE IS EXPECTED AS DRIER AIR BEGINS TO WORK INTO THE REGION. .SPOTTER INFORMATION STATEMENT SPOTTER ACTIVATION IS POSSIBLE IN SOME AREAS TODAY. REPORTS OF SIGNIFICANT WEATHER WILL AGAIN BE APPRECIATED. NL/MC
SPECIAL WEATHER STATEMENT NATIONAL WEATHER SERVICE GRAND JUNCTION CO 1048 AM MDT WED AUG 4 2010 COZ002-004-041745- CENTRAL YAMPA RIVER BASIN CO-ELKHEAD AND PARK MOUNTAINS CO- 1048 AM MDT WED AUG 4 2010 ...SIGNIFICANT WEATHER ADVISORY FOR NORTHEASTERN MOFFAT AND NORTHERN ROUTT COUNTIES UNTIL 1145 AM MDT... AT 1047 AM MDT...NATIONAL WEATHER SERVICE DOPPLER RADAR WAS TRACKING A STRONG THUNDERSTORM 12 MILES SOUTHEAST OF DIXON...OR 29 MILES NORTH OF CRAIG...MOVING EAST AT 20 MPH. HAIL UP TO ONE-HALF INCH IN DIAMETER AND WIND GUSTS UP TO 50 MPH ARE EXPECTED WITH THIS STORM...ALONG WITH HEAVY RAIN AND FREQUENT DANGEROUS LIGHTNING. LOCATIONS NEAR THE PATH OF THIS STORM INCLUDE... HAHNS PEAK... TORRENTIAL RAIN...WHICH MAY FLOOD LOW LYING AREAS SUCH AS DITCHES AND UNDERPASSES...IS ALSO LIKELY. DO NOT DRIVE YOUR VEHICLE ON A FLOODED ROADWAY.
SPECIAL WEATHER STATEMENT NATIONAL WEATHER SERVICE GRAND JUNCTION CO 1051 AM MDT WED AUG 4 2010 COZ001-UTZ024-025-041730- EASTERN UINTA BASIN UT-LOWER YAMPA RIVER BASIN CO-TAVAPUTS PLATEAU UT- 1051 AM MDT WED AUG 4 2010 ...SIGNIFICANT WEATHER ADVISORY FOR SOUTHEASTERN UINTAH AND SOUTHWESTERN RIO BLANCO COUNTIES UNTIL 1130 AM MDT... AT 1047 AM MDT...NATIONAL WEATHER SERVICE DOPPLER RADAR WAS TRACKING A STRONG THUNDERSTORM 20 MILES SOUTH OF BONANZA...MOVING NORTHEAST AT 20 MPH. HAIL UP TO ONE-HALF INCH IN DIAMETER AND WIND GUSTS UP TO 40 MPH ARE EXPECTED WITH THIS STORM...ALONG WITH HEAVY RAIN AND FREQUENT DANGEROUS LIGHTNING. LOCATIONS NEAR THE PATH OF THIS STORM INCLUDE... MAINLY RURAL AREAS OF EXTREME WESTERN RIO BLANCO AND SOUTHEASTERN UINTAH COUNTIES. TORRENTIAL RAIN...WHICH MAY FLOOD LOW LYING AREAS SUCH AS DITCHES AND UNDERPASSES...IS ALSO LIKELY. DO NOT DRIVE YOUR VEHICLE ON A FLOODED ROADWAY.
SPECIAL WEATHER STATEMENT NATIONAL WEATHER SERVICE GRAND JUNCTION CO 1137 AM MDT WED AUG 4 2010 UTZ025-041815- TAVAPUTS PLATEAU UT- 1137 AM MDT WED AUG 4 2010 ...SIGNIFICANT WEATHER ADVISORY FOR SOUTHERN UINTAH AND NORTHERN GRAND COUNTIES UNTIL 1215 PM MDT... AT 1134 AM MDT...NATIONAL WEATHER SERVICE DOPPLER RADAR WAS TRACKING A STRONG THUNDERSTORM 41 MILES SOUTH OF OURAY...OR 41 MILES SOUTHWEST OF BONANZA...MOVING EAST AT 10 MPH. HAIL UP TO THE SIZE OF PENNIES AND WIND GUSTS UP TO 50 MPH ARE EXPECTED WITH THIS STORM...ALONG WITH HEAVY RAIN AND FREQUENT DANGEROUS LIGHTNING. LOCATIONS NEAR THE PATH OF THIS STORM INCLUDE... MAINLY RURAL AREAS OF NORTHERN GRAND AND SOUTHERN UINTAH COUNTIES. TORRENTIAL RAIN...WHICH MAY FLOOD LOW LYING AREAS SUCH AS DITCHES AND UNDERPASSES...IS ALSO LIKELY. DO NOT DRIVE YOUR VEHICLE ON A FLOODED ROADWAY.
SPECIAL WEATHER STATEMENT NATIONAL WEATHER SERVICE GRAND JUNCTION CO 109 PM MDT WED AUG 4 2010 COZ001-002-013-042000- CENTRAL YAMPA RIVER BASIN CO-FLATTOPS CO-LOWER YAMPA RIVER BASIN CO- 109 PM MDT WED AUG 4 2010 ...SIGNIFICANT WEATHER ADVISORY FOR NORTHERN RIO BLANCO AND SOUTHERN MOFFAT COUNTIES UNTIL 200 PM MDT... AT 106 PM MDT...NATIONAL WEATHER SERVICE DOPPLER RADAR WAS TRACKING A STRONG THUNDERSTORM 17 MILES NORTHWEST OF MEEKER...OR 35 MILES SOUTHWEST OF CRAIG...MOVING NORTHEAST AT 10 MPH. HAIL UP TO THE SIZE OF PENNIES AND WIND GUSTS UP TO 40 MPH ARE EXPECTED WITH THIS STORM...ALONG WITH HEAVY RAIN. LOCATIONS NEAR THE PATH OF THIS STORM INCLUDE... JUNIPER SPRINGS... TORRENTIAL RAIN...WHICH MAY FLOOD LOW LYING AREAS SUCH AS DITCHES AND UNDERPASSES...IS ALSO LIKELY. DO NOT DRIVE YOUR VEHICLE ON A FLOODED ROADWAY.
The Grand Junction radar (KGJX), 85 km away, was scanning. The volume nearest the first event began at 19:10 UTC.
4 heavy rain, 1 hail. Local standard time, as filed.
Large hail up to 1.0 inch in diameter fell about 3 miles east of New Castle.
Heavy rainfall caused mud and rocks to slide across Highway 13, blocking the Highway north of Rifle between mile markers 7 and 10.
Heavy rainfall caused minor flooding to occur over low water crossings along Highway 64 near Rangely.
Heavy rainfall caused a minor mudslide across Highway 160 just north of Pagosa Springs. The slide was about 6 to 8 feet wide and up to two and a half feet deep at its deepest sections. Rainfall amounts up to 0.50 inches within a 20 minute time period were reported just west of Pagosa Springs.
Runoff from heavy rainfall was running up to 6 inches deep in the normally dry canyons of the Colorado National Monument.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Colorado in 2010Every state in 2010This day in weather historyWarnings in Colorado, August 2010
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: 257700, 257702, 257699, 257698, 257701.