1 flash flood, as filed by the National Weather Service.
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.
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.
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 Sioux Falls, SD wrote its last area forecast discussion before the first event at Aug 22, 2:05 AM CST, 25 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE SIOUX FALLS SD 305 AM CDT THU AUG 22 2002 CONVECTION CHANCES REMAIN THE BIGGEST CONCERN THIS MORNING. TWO DISTINCT AREAS OF ONGOING CONVECTION AS OF 08Z. THE FIRST IS THE PERSISTENT BAND RIGHT ALONG THE WARM FRONT ACROSS NORTHWEST IOWA... WITH REDEVELOPMENT OVER THE SAME AREAS OF CHEROKEE AND BUENA VISTA COUNTIES. WILL LIKELY BE LOOKING AT SOME PRETTY SIGNIFICANT RAIN TOTALS FROM THIS AREA. THE SECOND AREA IS ASSOCIATED WITH SHORTWAVE MOVING EAST ACROSS SOUTH DAKOTA. ONE VERY PERSISTENT CELL ON THE LEADING EDGE HAS BEEN HANGING ON FOR MANY HOURS...AND HAVE BEEN GETTING SOME ADDITIONAL DEVELOPMENT FARTHER WEST INTO SOUTHCENTRAL SD WITHIN THE LAST COUPLE OF HOURS. RECEIVED A COUPLE REPORTS OF DIME TO NICKEL SIZE HAIL WITH THE LEADING CELL AT ITS STRONGEST POINT...BUT AGAIN MAINLY LOOKING AT HEAVY RAINS. THIS AREA WILL CONTINUE TO SWING EAST ACROSS THE CWA THIS MORNING...EVENTUALLY JOINING FORCES WITH ADDITIONAL BAND ACROSS NORTHWEST IOWA. WILL HANG ONTO SCATTERED TSRA THROUGH MID MORNING ACROSS WESTERN 2/3RDS OF CWA AND THROUGH THE MORNING IN THE FAR EAST. THEN ATTENTION TURNS TO ANOTHER SHORTWAVE FORECAST BY BOTH ETA AND AVN TO SWING THROUGH SD LATE THIS AFTERNOON AND EVENING. NOT MUCH FOR INSTABILITY WITH THIS...BUT WITH LINGERING MOISTURE ACROSS THE AREA...SHORTWAVE COULD BE ENOUGH TO TRIGGER ANOTHER ROUND OF SHOWERS AND THUNDERSTORMS LATER TODAY...AND HAVE ADDED A CHANCE THROUGHOUT THE CWA TO COVER THIS. ALSO PRETTY EXTENSIVE LOW CLOUDS ACROSS THE AREA EARLY THIS MORNING WITH AREAS OF FOG IN UPSLOPE AREAS EAST OF THE BUFFALO RIDGE. THIS SHOULD BREAK UP SOME AS THE RAIN MOVES THROUGH...BUT WE WILL BE LOOKING AT PLENTY OF RESIDUAL LOW LEVEL MOISTURE RESULTING IN A DECENT AMOUNT OF STRATOCU/CU DEVELOPMENT THROUGHOUT THE DAY. WITH THE ABUNDANT MOISTURE AND LITTLE IN THE WAY OF LOW LEVEL WINDS... THINK TEMPS WILL HAVE A HARD TIME SEEING MUCH RECOVERY...AND HAVE LOWERED TEMPS A CATEGORY OR SO FOR HIGHS TODAY. REMAINDER OF THE FORECAST LOOKS REASONABLE AND HAVE NOT CHANGED TOO MUCH FROM PREVIOUS FORECAST. .FSD...NONE HACKER
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE SIOUX FALLS SD
316 AM CDT THU AUG 22 2002
TIME(CDT) .....CITY LOCATION.....STATE ...EVENT/REMARKS...
....COUNTY LOCATION....
0715 PM 5 N DALLAS SD 60 MPH TSTM GUST
08/21/02 GREGORY REPORTED BY PUBLIC.
TREE BRANCHES DOWN.
0720 PM 10 N GREGORY SD 1 INCH HAIL
08/21/02 GREGORY MARBLE TO QUARTER SIZE
HAIL COVERNING HIGHWAY
44. REPORTED BY LAW
ENFORCEMENT OFFICIAL.
0103 AM MT VERNON SD .88 INCH HAIL
08/22/02 DAVISON REPORTED BY EMERGENCY
MANAGEMENT.
0112 AM MT VERNON SD .75 INCH HAIL
08/22/02 DAVISON REPORTED BY STORM
SPOTTER.The Sioux Falls radar (KFSD), 130 km away, was scanning. The volume nearest the first event began at 08:30 UTC.
1 flash flood. Local standard time, as filed.
Heavy rain amounting to over four inches caused flooding of roads and basements. Maple creek rose out of its banks and up to the bottom of a bridge on Iowa Highway Seven.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Iowa in 2002Every state in 2002This day in weather historyWarnings in Iowa, August 2002
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: 5317677.