A strong thunderstorm in a very moist monsoonal airmass produced a funnel cloud over the Uncompahgre Plateau.
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The episode as NWS GJT wrote it up.
A strong thunderstorm in a very moist monsoonal airmass produced a funnel cloud over the Uncompahgre Plateau.
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, 1:21 PM MST, 1 hour 24 minutes earlier.
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND JUNCTION CO
221 PM MDT WED AUG 4 2010
.SHORT TERM...TONIGHT THROUGH FRIDAY...
ACTIVE DAY TODAY AS ANOTHER ROUND OF CONVECTION HAS FIRED ACROSS
ENTIRE CWA. MAIN CONCERN TODAY WAS LONG LINE OF STORMS THAT FORMED
ALONG TAVAPUTS FROM GREEN RIVER UT...ALL THE WAY TO JUST WEST OF
STEAMBOAT SPRINGS. STRONG RETURNS INDICATED HAIL...AND ESPECIALLY
HEAVY RAIN SO WENT AHEAD AND EXTENDED FLASH FLOOD WATCH TO INCLUDE
ALL AREAS N OF I-70. ISSUED FLOOD ADVISORY THAT ENCOMPASSES ENTIRE
TAVAPUTS PLATEAU AS FLOODING OF LOW-LYING STREAMS IS CERTAINLY
POSSIBLE. REMAINDER OF THIS AFTN AND EVENING WILL SEE STORMS
CONTINUING...SOME BECOMING SEVERE WITH HAIL AROUND AN INCH AND
HEAVY RAINFALL. EXPECT SOME SHOWERS TO CONTINUE THROUGH MIDNIGHT
THOUGH MOST CONVECTION WILL END AN HOUR OR TWO AFTER SUNSET.
MODELS CONTINUE TO PAINT MONSOONAL FLOW USHERING IN MOIST AIR
THOUGH PWATS DO LOWER TO .8 INCHES TOMORROW AS OPPOSED TO OVER 1.2
INCHES THE LAST FEW DAYS. ALL MODELS CONTINUE TO PAINT QPF ACROSS
SRN CO AND EXTREME ERN UT SO GIVEN THE NATURE OF HOW MODELS HAVE
HANDLED CONVECTION DURING THIS PERIOD...KEPT POPS UP FOR ENTIRE
CWA. SHORTWAVES PROGGED TO CONTINUE RIDING UP ALONG WEAK SHEAR AXIS
SO DO ANTICIPATE MORE STORMS AND SHOWERS TOMORROW. HAVE NOT ISSUED
FLASH FLOOD WATCH FOR TOMORROW AS AFOREMENTIONED PWAT VALUES HAVE
DROPPED OFF BUT WILL ALERT NEXT SHIFT TO POSSIBILITY.
NOT MUCH CHANGE FRIDAY WITH VERY LITTLE CHANGE TO FORECAST AS
STAGNANT WX PATTERN KEEPS HIGH PRESSURE OVER DEEP SOUTH WITH MEAN
FLOW PUMPING IN MONSOONAL FLOW. MORE STORMS AND SHOWERS...YET
AGAIN.
.LONG TERM...FRIDAY NIGHT THROUGH WEDNESDAY...
NOT A LOT OF TIME TO DEVOTE TO THE FORECAST FOR THESE PERIODS DUE TO
CURRENT SEVERE WEATHER. AFTER A DOWNTURN IN MOISTURE THROUGH FRIDAY
NIGHT...THE WEST COAST TROUGH STRENGTHENS AND PUSHES THE SUBTROPICAL
RIDGE FURTHER EAST. THIS ALLOWS DEEPER MOISTURE TO RETURN SATURDAY.
WE CONTINUE TO WATCH A SIGNIFICANT EXTRA-TROPICAL DISTURBANCE
ROUNDING THE WESTERN TROUGH AND MOVING OVER THE NW PORTION OF THE
FORECAST AREA ON MONDAY. THIS MAY PRODUCE STRONGER STORMS WITH HAIL
POTENTIAL OVER NE UTAH AND FAR NW COLORADO. TUESDAY-WEDNESDAY...DRIER
AIR ASSOCIATED WITH THE WESTERN TROUGH INTRUDES INTO THE WESTERN
FORECAST AREA. THIS WOULD ALSO INCREASE THE DIURNAL TEMPERATURE
SPREAD.
&&
.AVIATION...
EXPECT SCATTERED TO NUMEROUS SHOWERS AND THUNDERSTORMS...ESPECIALLY
DURING THE AFTERNOON AND 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. ACTIVITY WILL
DECREASE OVERNIGHT WITH SIMILAR CONDITIONS EXPECTED THURSDAY.
&&
.GJT WATCHES/WARNINGS/ADVISORIES...
CO...FLASH FLOOD WATCH UNTIL 9 PM MDT THIS EVENING FOR ZONES 1>14-
17>23.
UT...FLASH FLOOD WATCH UNTIL 9 PM MDT THIS EVENING FOR ZONES 22>25-
27>29.
SHORT TERM.....TGR
LONG TERM......JOE
AVIATION.......TGJTHAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE GRAND JUNCTION CO 124 PM MDT WED AUG 4 2010 COZ001>014-017>023-UTZ022>025-027>029-051130- 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- 124 PM MDT WED AUG 4 2010 ...FLASH FLOOD WATCH IN EFFECT FROM NOON THROUGH THIS EVENING FOR ALL OF EASTERN UTAH AND WESTERN 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 WELL INTO THE EVENING. 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 EASTERN UTAH AND WESTERN COLORADO...ESPECIALLY NEAR STEEP TERRAIN AND IN NARROW SLOT CANYONS. THEREFORE...A FLASH FLOOD WATCH WILL BE IN EFFECT FOR THESE AREAS THROUGH THIS 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. MDA/TGR
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE GRAND JUNCTION CO
126 PM MDT WED AUG 04 2010
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
1250 PM HEAVY RAIN GLADE PARK 39.00N 108.73W
08/04/2010 M1.00 INCH MESA CO TRAINED SPOTTER
RAINFALL OCCURRED WITHIN 65 MINUTES. NO FLOODING
REPORTED.
&&
EVENT NUMBER GJT1000649
PRINGLEPRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE GRAND JUNCTION CO
134 PM MDT WED AUG 04 2010
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0109 PM HAIL 3 E NEW CASTLE 39.59N 107.47W
08/04/2010 E1.00 INCH GARFIELD CO COCORAHS
MINOR LEAF DAMAGE.
&&
EVENT NUMBER GJT1000650
MALEKSAPRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE GRAND JUNCTION CO
236 PM MDT WED AUG 04 2010
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0222 PM HEAVY RAIN 10 N RIFLE 39.68N 107.78W
08/04/2010 U0.00 INCH GARFIELD CO DEPT OF HIGHWAYS
ROAD BLOCKED DUE TO MUD AND ROCKSLIDE ON CO-13 BETWEEN
MM 7 AND 10 NORTH OF RIFLE.
&&
EVENT NUMBER GJT1000651
MALEKSASPECIAL WEATHER STATEMENT NATIONAL WEATHER SERVICE GRAND JUNCTION CO 237 PM MDT WED AUG 4 2010 COZ003-006-042115- GRAND VALLEY CO-ROAN AND TAVAPUTS PLATEAUS CO- 237 PM MDT WED AUG 4 2010 ...SIGNIFICANT WEATHER ADVISORY FOR NORTHWESTERN MESA AND SOUTHWESTERN GARFIELD COUNTIES UNTIL 315 PM MDT... AT 234 PM MDT...NATIONAL WEATHER SERVICE DOPPLER RADAR WAS TRACKING A STRONG THUNDERSTORM 11 MILES NORTHWEST OF FRUITA...OR 22 MILES NORTHWEST OF GRAND JUNCTION...MOVING NORTHEAST AT 5 MPH. HAIL UP TO THE SIZE OF NICKELS 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 NORTHWESTERN MESA AND SOUTHWESTERN GARFIELD 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 315 PM MDT WED AUG 4 2010 COZ006-017-UTZ027-042200- ARCHES/GRAND FLAT UT-GRAND VALLEY CO-UNCOMPAHGRE PLATEAU/DALLAS DIVIDE CO- 315 PM MDT WED AUG 4 2010 ...SIGNIFICANT WEATHER ADVISORY FOR EASTERN GRAND AND WESTERN MESA COUNTIES UNTIL 400 PM MDT... AT 310 PM MDT...NATIONAL WEATHER SERVICE DOPPLER RADAR WAS TRACKING A STRONG THUNDERSTORM 14 MILES SOUTHWEST OF FRUITA...OR 21 MILES WEST OF GRAND JUNCTION...MOVING EAST AT 5 MPH. HAIL UP TO THE SIZE OF NICKELS IS EXPECTED WITH THIS STORM...ALONG WITH HEAVY RAIN AND FREQUENT DANGEROUS LIGHTNING. LOCATIONS NEAR THE PATH OF THIS STORM INCLUDE... FRUITA... GLADE PARK... 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 315 PM MDT WED AUG 4 2010 COZ017-020-042200- PARADOX VALLEY/LITTLE DOLORES RIVER CO-UNCOMPAHGRE PLATEAU/DALLAS DIVIDE CO- 315 PM MDT WED AUG 4 2010 ...SIGNIFICANT WEATHER ADVISORY FOR NORTHERN SAN MIGUEL AND SOUTHERN MONTROSE COUNTIES UNTIL 400 PM MDT... AT 310 PM MDT...NATIONAL WEATHER SERVICE DOPPLER RADAR WAS TRACKING A STRONG THUNDERSTORM NEAR NORWOOD...OR 35 MILES SOUTHWEST OF MONTROSE...MOVING NORTH AT 10 MPH. HAIL UP TO THE SIZE OF NICKELS AND WIND GUSTS UP TO 50 MPH ARE EXPECTED WITH THIS STORM...ALONG WITH HEAVY RAIN AND FREQUENT DANGEROUS LIGHTNING. AREAS AFFECTED INCLUDE NORWOOD AND REDVALE THROUGH 4 PM MDT. THIS STORM MAY INTENSIFY...SO BE CERTAIN TO MONITOR LOCAL RADIO AND TV STATIONS...AS WELL AS LOCAL CABLE TV OUTLETS... FOR ADDITIONAL INFORMATION AND POSSIBLE WARNINGS FROM THE NATIONAL WEATHER SERVICE. 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. MDA
The Grand Junction radar (KGJX), 38 km away, was scanning. The volume nearest the first event began at 21:46 UTC.
1 funnel cloud. Local standard time, as filed.
This funnel cloud was observed by mobile Skywarn spotters who were near the funnel cloud, as well as some NWS employees who were at the Grand Junction forecast office. Several photographs were taken of the funnel cloud that emanated from a classic wall cloud.
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: 327911.