Flash Flood in Iowa, August 24, 2001

Name: Flash Flood in Iowa, August 24, 2001
Start: 2001-08-24T18:45
End: 2001-08-24T18:45
Location: Iowa

August 24, 2001 · NWS DMX · 1 event in 1 county or zone

An area of thunderstorms developed over northwest and west central Iowa during the late afternoon and early evening hours. Deep moisture was in place over the state, combined with light winds aloft.

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: $25,000
Crop damage: $5,000
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 happened

The episode as NWS DMX wrote it up.

An area of thunderstorms developed over northwest and west central Iowa during the late afternoon and early evening hours. Deep moisture was in place over the state, combined with light winds aloft. The result was very heavy rainfall. Southeast Sac County reported six to seven inches of rainfall in a two to three hour period. This caused considerable street flooding in towns in southeast Sac County, and minor flash flooding in the surrounding countryside.

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 Des Moines, IA wrote its last area forecast discussion before the first event at Aug 24, 11:58 AM CST, 6 hours 47 minutes earlier.

Area forecast discussion, Aug 24, 11:58 AM CST, 6 hours 47 minutes before

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DES MOINES IA
1258 PM CDT FRI AUG 24 2001

SHORT TERM...
MESOETA IS DEFINITELY A BIT OFF ON THE SURFACE WARM FRONT AND LOW.
THIS MAY BRING ENOUGH WARM SECTOR INTO SOUTHERN SECTIONS FOR CONCERN
OF STRONGER CELL DEVELOPMENT LATER TODAY DURING PEAK HEATING.
DIRECTIONAL SHEAR MAY BE SUFFICIENT FOR SOME CELL ROTATION, SO WILL
HAVE TO WATCH, BUT NOT CONCERNED ABOUT HAIL OR STRAIGHT LINE WINDS
AS PER SPC DY1.  SHRA BAND AMIDST DZ AND -RA IS ALONG 850MB WIND
SHIFT, LACKING A SUBSTANTIAL TEMP GRADIENT BY THE WAY, SO MOST OF
LIFT BY DYNAMICS VS ADVECTION/ISENTROPIC ASCENT.  SHARS EVENT IS OF
CONCERN THIS EVENING, WITH MODELS SHOWING QUITE SIMILAR RESULTS.
QPF BULLSEYES ARE SIMILAR BETWEEN ETA/NGM WITH AVN FOCUSING MORE ON
IL WITH STRONGER LLJ THIS EVENING.  NOT SURE I BUY THIS, BUT IN
EITHER CASE, AM FAVORING TWO AREAS OF HEAVY PRECIP.  ONE WITHIN
DEVELOPING DEF ZONE AND CONVERGENCE MAX N AND NE OF LOW CENTER WHICH
WILL CONTINUE TO BE OVER NW/NC/WC IA, WITH SECONDARY AREA IN SE IA
INTO IL, SOMEWHAT AGREEING WITH THE AVN WHEN BETTER ISENTROPIC
ASCENT DEVELOPS THIS EVENING.  IOWA STATE ENSEMBLE ETA ALSO SHOWING
SIMILAR SOLUTIONS.  SHARS PARAMETERS OF A SYNOPTIC CYCLONIC
CIRCULATION ARE MOSTLY IN PLACE.  PWATS ACTUALLY A BIT HIGHER THAN
REQUIRED, WITH WARM TOPPED ACTIVITY QUITE POSSIBLE TONIGHT.  LOW IS
PROGGED TO MOVE, SO DURATION MORE ALONG LINES OF 6 TO 12 HOURS.  NO
FFA JUSTIFIED YET WITH RATHER HIGH VALUES, BUT IF STATIONARY CLUSTER
DEVELOPS AND CONFIDENCE INCREASES, WE MAY NEED ONE THIS EVENING.
WILL GO ABOVE GUIDANCE TEMPS TONIGHT WITH PLENTY OF FG AND DZ
ANYWHERE THERE ISNT RAIN.

LONGER TERM...
WILL KEEP SKIES MO CLOUDY ALL DAY, AND HANG ON TO PRECIP LONGEST IN
NE QUADRANT OF CWA ON TRAILING DEF ZONE.  WILL BE TOUGH TO DRY OUT
ATMOSPHERE UNTIL COLD FRONT ARRIVES SAT NIGHT.  THIS FRONT WILL NOT
HAVE MUCH PUSH EITHER, SO WILL KEEP CLOUDS AND SOME FG MENTION AT
LEAST S HALF ALL NIGHT.  TEMPS SATURDAY LOOK OK, ESPECIALLY IF A FEW
BREAKS CAN OPEN UP.  SAT NIGHT STILL A BIT COOL THOUGH WITH EXPECTED
CLOUDS/FG.  NICE JET THIS MORNING ENTERING CA, BUT IT WILL CONTINUE
TO BE SPLIT OFF AND DISSIPATED WITH UPPER RIDGE AGAIN BUILDING IN
THE W.  NW FLOW WILL KEEP THINGS A BIT OF A CHALLENGE THOUGH WITH
ANOTHER SHORTWAVE ENTERING NORTHERN PLAINS 48-60 HR TIME FRAME. THIS
WAVE LIKELY TO ARRIVE A BIT SOONER IN PRESENT EXTENDED ZONE/GRID
PACKAGE.  WILL INTRODUCE POPS ON WED, ALTHOUGH WOULDNT DOUBT WAA
INCREASE TUESDAY NIGHT COULD DEVELOP ELEVATED MCS THAT WILL RESUME
ON WED.  DECENT COLD FRONT ARRIVES WED AND LEAVES THU, BUT WILL KEEP
CHANCE INTO THURSDAY AS THE FRONT SLOWS.  MRF BRINGS GLANCING BLOW
TO COOLEST AIR, BUT WILL STAY CLOSE WITH MEX LOW TEMPS LATE THIS
WEEK.  HIGHS LOOK A BIT TOO COOL AS GREAT LAKES HIGH STAYS E OF OUR
REGION.

.DSM...NONE.

KULA

The radar

The Des Moines radar (KDMX), 135 km away, was scanning. The volume nearest the first event began at 00:42 UTC.

Open the radar archive at this moment

Event by event

1 flash flood. Local standard time, as filed.

Flash Flood, Sac

When: August 24, 6:45 PM CST
Where: Sac County, Southeast Portion
Property damage: $25,000
Crop damage: $5,000
Reported by: LAW ENFORCEMENT
Coordinates: 42.386, -95.105 (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 Iowa in 2001 Every state in 2001 This day in weather history Warnings in Iowa, August 2001

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: 5260973.