Flash Flood in Utah, September 29, 2002

Name: Flash Flood in Utah, September 29, 2002
Start: 2002-09-29T14:00
End: 2002-09-29T15:00
Location: Utah

September 29, 2002 · NWS GJT · 1 event in 1 county or zone

Heavy rains caused flash flooding estimated to be at least 6 feet deep through drainages running under Interstate 70. Several places still had 4 feet of standing water remaining after the flash flooding subsided.

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

Open the live radar over this ground

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.

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 Sep 29, 3:00 AM MST, 11 hours earlier.

Area forecast discussion, Sep 29, 3:00 AM MST, 11 hours before

WESTERN COLORADO & EASTERN UTAH AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND JUNCTION CO
400 AM MDT SUN SEP 29 2002

CLOSED UPPER LOW OVER THE WESTERN GREAT BASIN BECOMES AN OPEN WAVE..
AND IT WILL EJECT ACROSS WESTERN COLORADO THIS EVENING.  THIS WAVE
ACCELERATES EASTWARD THIS AFTERNOON THANKS TO A RAPIDLY APPROACHING
TROUGH TOWARD THE PACIFIC NORTHWEST.  BECAUSE OF THE QUICK EJECTION
THIS AFTERNOON.. A GOOD COUPLET OF LIFT AHEAD OF THIS WAVE AND
SUBSIDENCE BEHIND IT WILL BE EXPECTED.  RELATIVELY THICK CLOUD
SHIELD IN ADVANCE OF THIS WAVE WILL INHIBIT SURFACE WARMING TODAY..
BUT MID LEVEL COLD ADVECTION WILL BE SUFFICIENT TO ALLOW THE AIR MASS
TO BE UNSTABLE.  NOCTURNAL THUNDERSTORMS OVER NORTHWEST ARIZONA NEAR
THE COLD CORE GIVES CREDENCE TO THIS IDEA.  DEW POINTS HAVE RISEN
DURING THE PAST 24 HOURS WITH MID 40S TO LOWER 50S ACROSS THE
FORECAST AREA.  COMBINED WITH GOOD LIFT AND INSTABILITY THIS
AFTERNOON.. AREAL COVERAGE OF SHOWERS WILL BE NUMEROUS AND BECOME
WIDESPREAD IN THE MOUNTAIN AREAS.  RAPID CLEARING WILL OCCUR BEHIND
THE WAVE AS DRIER WESTERLY FLOW FOLLOWS IN ITS WAKE.  SHOWERS AND
THUNDERSTORMS WILL BE DECREASING FROM WEST TO EAST THIS EVENING.
VALLEY AREAS OF EASTERN UTAH MAY BECOME MOSTLY CLEAR AFTER MIDNIGHT.

NEXT FORECAST CONCERN REGARDS SURFACE COLD FRONT FROM UPSTREAM
PACIFIC NORTHWEST TROUGH.  MODELS SHOW THIS FRONT BECOMING
STATIONARY WITH INCREASING MOISTURE CONVERGENCE THROUGH THE FIRST
PART OF THIS WEEK.  BUT BELIEVE FRONT WILL INITIALLY STALL
NORTHWEST OF OUR FORECAST AREA (WEST OF THE WASATCH RANGE AND NORTH
OF THE UINTA MOUNTAINS).. AND WILL NOT BE A CONCERN FOR MONDAY
AFTERNOON.  PROXIMITY OF SOUTHWESTERLY JET CUTTING ACROSS WYOMING
WILL RESULT INTO A BREEZY AFTERNOON FOR MANY ZONES.. BUT DRY
CONDITIONS WILL PREVAIL.  WEATHER BECOMES MORE INTERESTING BEYOND
MONDAY.. THE DAY CREW WILL HAVE MORE DETAILS. FRISBIE

.GJT...NONE.

In the hours before

Local storm report, Sep 29, 12:01 PM MST, 1 hour 59 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE GRAND JUNCTION, CO
101 PM MDT SUN SEP 29 2002

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

1115 AM    1 N FRUITA                CO   .75 INCH HAIL
09/29/02   MESA                           REPORTED BY
                                          NWS EMPLOYEE

DJN

The radar

The Grand Junction radar (KGJX), 118 km away, was scanning. The volume nearest the first event began at 21:01 UTC.

Open the radar archive at this moment

Event by event

1 flash flood. Local standard time, as filed.

Flash Flood, Grand

When: September 29, 2:00 PM MST to 3:00 PM MST
Where: Grand County, Crescent Jct
Reported by: TRAINED SPOTTER
Coordinates: 38.982, -109.570 (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

Every storm in Utah in 2002 Every state in 2002 This day in weather history Warnings in Utah, September 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: 5320198.