Name: Flash Flood in Colorado, August 6, 2002
Start: 2002-08-06T16:00
End: 2002-08-06T17:00
Location: Colorado

Where it happened

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.

Tornadoes
Tropical storms and surge
Floods
Wind
Hail
Winter weather
Heat and drought
Cold
Fire, smoke and dust
Marine and coastal
Other

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The toll

Deaths: 0
Injuries: 0
Property damage: None recorded
Crop damage: None recorded
Events: 1

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.

What happened

The episode as NWS GJT wrote it up.

Flash flood waters up to two feet deep crossed over Highway 65 at the junction with Highway 330.

What forecasters said that day

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 6, 1:45 PM MST, 2 hours 15 minutes earlier.

Area forecast discussion, Aug 6, 1:45 PM MST, 2 hours 15 minutes before

WESTERN COLORADO & EASTERN UTAH AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND JUNCTION CO
245 PM MDT TUE AUG 6 2002

MONSOONAL PLUME CONTINUES WITH HEAVY RAINERS FORMING.  WINDS ALOFT
ARE SLOWER THAN MONDAY AFTERNOON CAUSING SLOWER CELL MOVEMENT.  WITH
HIGH PRECIPITABLE WATER AND SURFACE DEW POINTS IN THE 50S.. HAVE
ALREADY EXTENDED FLASH FLOOD WATCH UNTIL MIDNIGHT FOR A LARGE
PORTION OF OUR FORECAST AREA.  THE AIR MASS IS A LITTLE DRIER ACROSS
THE FAR NORTHERN COUNTIES.. THEREFORE HAVE NOT INCLUDED THEM IN THE
FLASH FLOOD WATCH AREA.

WEDNESDAY WILL BE A TRANSITION DAY AS CHANGES IN THE WEATHER
PATTERN BEGIN.  THE WESTERN EDGE OF THE MONSOONAL PLUME IS GRADUALLY
ERODING AWAY.  THE CULPRIT IS THE PACIFIC NORTHWEST TROUGH THAT IS
SLOWLY SHIFTING EASTWARD.  THIS WILL SHUNT THE PLUME EASTWARD.  THE
ENTIRE FORECAST AREA REMAINS UNDERNEATH THE PLUME IN THE MORNING..
BUT BY AFTERNOON.. MODEL DATA SHOWS THE WESTERN EDGE NEAR THE UTAH
AND COLORADO BORDER AND CONTINUES TO SHIFT EASTWARD WEDNESDAY
EVENING.  EXPECT LESS CONVECTIVE ACTIVITY.. ESPECIALLY THE NORTHERN
ZONES IN THE AFTERNOON.  AIR MASS WILL REMAIN PRIME TO HEAVY RAIN
FROM THE SAN JUAN MOUNTAIN AND SOUTHWARD.. SO PERSISTENCE FORECAST
WILL BE THE MAIN FORECAST THEME THERE.

LATEST AVN MODEL RUN SHOWS PACIFIC NORTHWEST TROUGH BECOMING A
CLOSED CIRCULATION OVER YELLOWSTONE BY THURSDAY AFTERNOON.  THE ETA
SHOWS THIS A LITTLE FARTHER NORTH.. BUT BOTH SOLUTIONS PLACES THE
ENTIRE FORECAST AREA WITHIN THE DRY SLOT.  GOODBYE MONSOONAL PLUME
WITH SOME GRADIENT WIND ACROSS THE NORTHERN ZONE.  RESIDUAL LOW LEVEL
MOISTURE OUGHT TO BE SUFFICIENT FOR SOME ISOLATED CONVECTION OVER THE
HIGHEST TERRAIN.. MAINLY THE SAN JUAN MOUNTAINS.  FRISBIE

EXTENDED (FRI-TUE)...FRIDAY LOOKS TO BE THE LAST DAY OF THIS LATEST
MONSOONAL BURST. THE 00Z MRF AND 06Z AVN HAVE SLIGHTLY DIFFERENT
SOLUTIONS TO THE TROF THAT SKIRTS OUR NORTHERN AREAS ON THAT DAY.
THE MRF KEEPS THE SYSTEM AS AN OPEN WAVE FARTHER TO THE NORTH...WHILE
THE AVN FORECASTS A CLOSED LOW THAT IS CLOSER TO THE CWA. EITHER
WAY, THE NORTHERN COUNTIES WILL HAVE A BETTER SHOT AT PRECIPITATION.

BY SATURDAY, THE FLOW ALOFT RETURNS TO A MORE WESTERLY DIRECTION.
THIS SHOULD PUT US BACK IN A MONSOONAL BREAK. SOME RESIDUAL
MOISTURE COULD SUPPLY THE MOUNTAIN AREAS WITH SOME AFTERNOON
CONVECTION, BUT THE MAJORITY OF THE AREA WILL LIKELY SEE NONE. SUNDAY
THROUGH TUESDAY LOOKS TO BE WARM AND DRY UNDER A WEST TO NORTHWEST
FLOW.  BA

.GJT...FLASH FLOOD WATCH UNTIL MIDNIGHT FOR SOUTHEAST UTAH AND
     MOST OF WESTERN COLORADO.

In the hours before

Local storm report, Aug 6, 1:26 PM MST, 2 hours 34 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE GRAND JUNCTION, CO
226 PM MDT TUE AUG 6 2002

TIME(MDT)  .....CITY LOCATION.....STATE   ...EVENT/REMARKS...
           ....COUNTY LOCATION....

0215 PM    6NW GATEWAY               CO   FLASH FLOODS
08/06/02   MESA                           SHEEP CREEK OUT OF ITS
                                          BANKS. 6-8 FEET OF WATER
                                          ACROSS ROAD TO GATEWAY.
                                          RANCHERS STRANDED.REPORTED
                                          BY SPOTTERS

BA

The radar

The Grand Junction radar (KGJX), 22 km away, was scanning. The volume nearest the first event began at 23:02 UTC.

Open the radar archive at this moment

Event by event

1 flash flood. Local standard time, as filed.

Flash Flood, Mesa

When: August 6, 4:00 PM MST to 5:00 PM MST
Where: Mesa County, 2 mi N of Mesa
Reported by: NWS EMPLOYEE(OFF DUTY)
Coordinates: 39.018, -108.466 (the zone’s center; the record gives no point)

What these are

Flash Flood: Flooding that begins within six hours of the rain that causes it, or of a dam or levee failure or ice jam release, often with deadly speed.

After NWS Directive 10-1605, the rules offices file Storm Data by.

The same day elsewhere

More

Every storm in Colorado in 2002 Every state in 2002 This day in weather history Warnings in Colorado, August 2002

Sources

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: 5317984.