A persistent monsoonal feed of moisture into Western Colorado allowed early morning thunderstorms to form over the San Juan Mountains and adjacent valleys. These storms contained frequent lightning and very heavy rainfall which fell over already saturated ground.
Every event with a place to put it; 1 filed by county or forecast zone are drawn at its center, in a lighter ring. 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.
A persistent monsoonal feed of moisture into Western Colorado allowed early morning thunderstorms to form over the San Juan Mountains and adjacent valleys. These storms contained frequent lightning and very heavy rainfall which fell over already saturated ground.
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 5, 3:30 AM MST, 2 hours 30 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GRAND JUNCTION CO 430 AM MDT THU AUG 5 2010 .SHORT TERM...TODAY THROUGH FRIDAY NIGHT... EMBEDDED VORT CENTER OVER SE UTAH HAS TRIGGERED AN AREA OF STORMS ACROSS SAN JUAN COUNTY UTAH EARLY THIS MORNING. THIS VORT CENTER IS PROGGED TO MOVE NORTHEAST AND REACH THE LA SAL MOUNTAINS BY LATE MORNING...A GOOD AREA FOR STORM DEVELOPMENT. THIS WILL BE QUICKLY FOLLOWED BY A STRONGER SHORT WAVE OVER NW ARIZONA THAT WILL LIFT NORTHEAST TODAY AND REACH THE UINTA BASIN THIS EVENING. RUC13 AND SREF MODELS PLACE THE DEEPEST MOISTURE OVER SE UTAH AND WEST CENTRAL COLORADO...SO THIS REGION SHOULD BE THE PRIMARY AREA OF FOCUS. MOISTURE IS NOT AS DEEP COMPARED TO THE PAST SEVERAL DAYS...BUT REMAINS ABOVE SEASONAL NORMS WITH PRECIPITABLE WATER OVER AN INCH ACROSS SE UTAH. WILL ISSUE ANOTHER FLASH FLOOD WATCH TODAY FOR THE SRN TWO THIRDS OF THE FORECAST AREA. FRIDAY...SOMEWHAT DRIER AIR FOLLOWS THE DEPARTING SHORT WAVE. MAXIMUM PRECIPITABLE WATER MAY BE UNDER ONE INCH AND PROGGED 700 MB SPECIFIC HUMIDITY GENERALLY LESS THAN 8 G/KG. THERE ARE STILL MINOR IMPULSES EMBEDDED IN LIGHT SOUTHWEST FLOW THAT WILL TRIGGER STORMS... BUT CONVECTION MAY NOT BE AS STRONG OR ORGANIZED AS THE PAST SEVERAL DAYS. BARRING ANY SURPRISES...A FLASH FLOOD WATCH MAY NOT BE WARRANTED. FRIDAY NIGHT...THE NEXT MONSOONAL SURGE MAY NOT WAIT UNTIL SATURDAY AS THE MODELS SUGGEST MOISTURE WILL BE ON THE RISE OVER SOUTHWEST COLORADO. THIS HAS IMPLICATIONS IN THE LONG TERM PERIOD...BUT FOR THE SHORT TERM...MOST OF FRIDAYS ACTIVITY WILL DIMINISH BY LATE EVENING. .LONG TERM...SATURDAY THROUGH WEDNESDAY... HIGH PRESSURE WILL BECOME RE-CENTERED OVER TX SATURDAY BRINGING A A SECOND SURGE OF MOISTURE NORTHWARD INTO OUR CWA. COINCIDENTALLY TROF ALONG THE WEST COAST TRIES TO MOVE EASTWARD AND 60KT JET CORE MOVES INTO NRN UT. THIS SHOULD SET THE STAGE FOR STRONGER MORE ORGANIZED STORMS DUE TO INCREASING SHEAR WITH THE POSSIBILITY OF DECENT SIZED HAIL. LITTLE CHANGE IS SEEN SUNDAY OTHER THAN MSTR CONTINUES TO INCREASE AND JET REMAINS IN THE SAME AREA. THE STRONGEST STORMS SHOULD FAVOR ERN UT AND NW CO...WHILE THE WETTEST STORMS WILL BE IN THE DEEPER MSTR NEAR THE SOUTHERN PORTION OF CONTINENTAL DIVIDE. MONDAY LIMITED DRYING OCCURS FROM THE WEST-NORTHWEST AS TROF TRIES TO MOVE INTO THE GRT BASIN. EXPECT COVERAGE OF STORMS TO LESSEN TO SCT CATEGORY MTNS AND ISOLD VALLEYS. TUESDAY-WEDNESDAY...DRIER AIR ASSOCIATED WITH THE WESTERN TROUGH INTRUDES INTO THE WESTERN FORECAST AREA. THIS WOULD ALSO INCREASE THE DIURNAL TEMPERATURE SPREAD. && .AVIATION... STORMS WILL QUICKLY DEVELOP MID MORNING AND PERSIST THROUGH THE LATE EVENING HOURS. 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 WITH UP TO INCH SIZED HAIL IN STRONGER STORMS. && .GJT WATCHES/WARNINGS/ADVISORIES... CO...NONE. UT...NONE. SHORT TERM.....PF LONG TERM......MC/JOE AVIATION.......TGJT
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE GRAND JUNCTION CO 600 AM MDT THU AUG 5 2010 COZ001>014-017>023-UTZ022>025-027>029-061200- 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 THU AUG 5 2010 THIS HAZARDOUS WEATHER OUTLOOK IS FOR EASTERN UTAH AND WESTERN COLORADO. .DAY ONE...TODAY AND TONIGHT SHOWERS AND THUNDERSTORMS WILL BE NUMEROUS THIS AFTERNOON AND EVENING ACROSS MUCH OF WESTERN COLORADO AND EASTERN UTAH. THE STRONGEST THUNDERSTORMS WILL PRODUCE HAIL...GUSTY WINDS TO 30 MPH AND VERY HEAVY RAINFALL. DOWNPOURS WILL LIKELY RESULT IN FLASH FLOODING ACROSS PORTIONS OF EASTERN UTAH AND WESTERN COLORADO...ESPECIALLY NEAR STEEP TERRAIN AND IN NARROW SLOT CANYONS. PLEASE SEE THE GRAND JUNCTION NATIONAL WEATHER SERVICE WEB SITE AT WEATHER.GOV/GJT FOR THE LATEST INFORMATION. .DAYS TWO THROUGH SEVEN...FRIDAY THROUGH WEDNESDAY FRIDAY...EXPECT SCATTERED SHOWERS AND THUNDERSTORMS WITH LOCALLY HEAVY RAIN...HOWEVER STORMS WILL NOT BE AS STRONG AS PREVIOUS DAYS... AND THE FLASH FLOODING THREAT WILL BE LOWER. SATURDAY AND SUNDAY...MONSOONAL MOISTURE WILL BE ON THE INCREASE WITH STRONGER AND ORGANIZED STORMS. THE STRONGER STORMS WILL HAVE HEAVY RAIN AND HAIL. MONDAY THROUGH WEDNESDAY...NOT AS MOIST BUT SCATTERED SHOWERS AND THUNDERSTORMS CAN BE EXPECTED EACH AFTERNOON AND EARLY EVENING. .SPOTTER INFORMATION STATEMENT SPOTTER ACTIVATION IS POSSIBLE IN SOME AREAS TODAY. REPORTS OF SIGNIFICANT WEATHER WILL AGAIN BE APPRECIATED.
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE GRAND JUNCTION CO
258 AM MDT THU AUG 05 2010
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0800 PM LIGHTNING 5 SE MOAB 38.52N 109.48W
08/04/2010 GRAND UT TRAINED SPOTTER
LIGHTNING STRUCK POWER POLE ON SOUTH SIDE OF KIRBY LANE
SOUTH OF MOAB. STARTED GRASS FIRE WHICH WAS QUICKLY
SUPRESSED. TIME ESTIMATED.
&&
EVENT NUMBER GJT1000655
MCSPRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE GRAND JUNCTION CO
312 AM MDT THU AUG 05 2010
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0946 PM HEAVY RAIN 5 W MOAB 38.57N 109.64W
08/04/2010 U0.00 INCH GRAND UT TRAINED SPOTTER
MUD AND SOME ROCK ON HWY 279 BETWEEN MM 10 AND 11. ALSO
SOME MUD ALONG HWY 128...NO SPECIFIED LOCATION. TIME
ESTIMATED.
&&
EVENT NUMBER GJT1000656
MCSThe Grand Junction radar (KGJX), 165 km away, was scanning. The volume nearest the first event began at 13:48 UTC.
1 debris flow, 1 lightning. Local standard time, as filed.
Heavy rain-induced rock slides were reported near the Rockwood station along the Durango and Silverton rail line. The damage closed the tracks for a few hours and delayed the train passage.
Lightning from an early morning thunderstorm struck the roof of a house in the Durango Hills subdivision. Only moderate damage was reported by the resulting fire.
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: 354663, 354662.