Name: Flash Flood in Utah, September 12, 2002
Start: 2002-09-12T18:00
End: 2002-09-12T23:30
Location: Utah

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: $3.0 million
Crop damage: $100,000
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 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 Salt Lake City, UT wrote its last area forecast discussion before the first event at Sep 12, 3:17 PM MST, 2 hours 43 minutes earlier.

Area forecast discussion, Sep 12, 3:17 PM MST, 2 hours 43 minutes before

UTAH AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SALT LAKE CITY UT
417 PM MDT THU SEP 12 2002

.SYNOPSIS...AN UPPER LOW OVER CENTRAL UTAH WILL SLOWLY MOVE EAST OF
THE AREA BY FRIDAY AFTERNOON. A RIDGE OF HIGH PRESSURE WILL DEVELOP
OVER THE AREA FOR THE WEEKEND.

.DISCUSSION...UPPER LEVEL CIRCULATION OVER CENTRAL UTAH WITH MOST
AND UNSTABLE AIRMASS IN PLACE. FLASH FLOOD WATCH CONTINUED UNTIL 100
AND EXPANDED TO INCLUDE WASATCH MOUNTAINS SOUTH OF I-80 AND BOOK
CLIFFS. SLOW MOVING SHOWERS CONTINUE IN THAT AREA AND RECENT BURN
AREAS WILL BE AFFECTED.

UPPER LOW WILL BEGIN TO SHIFT EAST FRIDAY WITH LINGERING INSTABILITY
MOUNTAIN AND EAST. RIDGE BUILDS IN FOR SATURDAY AND SUNDAY. WINDS
MAY INCREASE WESTERN VALLEYS SUNDAY AS NEXT SYSTEM APPROACHES. 12Z
AVN SHOWS A TROF ROTATING NORTHEAST ACROSS THE NORTHERN GREAT BASIN
MONDAY MORNING. THIS MAY PUSH A MAINLY DRY BUT WINDY COLD FRONT INTO
UTAH. NEW AVN ALSO DEEPER WITH FOLLOWING SHORTWAVE FOR TUESDAY.
ADDED A SHOWER THREAT FOR MONDAY AND TUESDAY NORTHERN SECTIONS WITH
THESE SYSTEMS. DRY FOR WEDNESDAY AND THURSDAY AND COOL.

SLC 5210 CDC 4211  GIBSON

.SLC...FFASLC...FLASH FLOOD WATCH MOST OF CENTRAL AND SOUTHERN
       UTAH UNTIL 1000 PM.

The radar

The Salt Lake City radar (KMTX), 143 km away, was scanning. The volume nearest the first event began at 00:57 UTC.

Open the radar archive at this moment

Event by event

1 flash flood. Local standard time, as filed.

Flash Flood, Utah

When: September 12, 6:00 PM MST to 11:30 PM MST
Where: Utah County, Santaquin
Property damage: $3.0 million
Crop damage: $100,000
Reported by: EMERGENCY MANAGER
Coordinates: 40.120, -111.670 (the zone’s center; the record gives no point)

Heavy rains over several days caused flash flooding and mudslides below a burn area in Santaquin. The rain also caused a canal to overflow its banks in the same area, making conditions even worse. An estimated 3 million dollars damage was done to to about 40 homes and several vehicles as mudslides up to 7 feet deep moved down the hillside. No injuries were reported.

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 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: 5325454.