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 20, 1:30 PM CST, 7 hours 30 minutes earlier.
AREA FORECAST DISCUSSION...CORRECTION FOR DATE NATIONAL WEATHER SERVICE SIOUX FALLS SD 230 PM CDT TUE AUG 20 2002 ...ALL EYES ON IMPENDING SEVERE WEATHER/HEAVY RAIN EVENT... SYNOPSIS...MORNING UPPER AIR ANALYSIS INDICATED STRONG UPPER TROUGH DIGGING INTO THE PACIFIC NORTHWEST. SD SEEMED TO BE IN THE RIGHT REAR QUAD OF A 70 KNT JET STRETCHING FROM ND SOUTHEAST INTO THE GREAT LAKES. THIS IS LIKELY RESPONSIBLE FOR ONGOING CONVECTION OVER N-CNTRL SD. AT H5 SEVERAL SHORT WAVES WERE NOTED MOVING THROUGH THE ROCKIES...WITH THE FIRST OVER EASTERN WY...AND THE SECOND STRONGER WAVE INTO CO/NM. LOW LEVEL MOISTURE WAS COPIOUS ACROSS THE CNTRL PLAINS WITH AN H7 DP OF 9 ON THE KOAX 12Z SOUNDING. MID LEVEL TEMPS WERE WARMING ACROSS THE WESTERN HIGH PLAINS WITH +16 THIS MORNING AT KUNR. THIS WAS CONTINUING TO CAP SB CONVECTION ACROSS THE NORTHERN PLAINS. FORECAST...DIFFICULT FORECAST WITH A COUPLE DAYS OF CONVECTION AHEAD...AND MODELS ARE HAVING A HARD TIME KEEPING VORT MAXES STRAIGHT. PLENTY OF INSTABILITY COMING NORTH WITH THE WARM FRONT. AT 18Z WARM FRONT WAS LOCATED FROM SOUTHWEST SD SE INTO EAST CNTRL NEB. THUNDERSTORMS WERE CONTINUING TO DEVELOP IN WAA ZONE NORTH OF THE WARM FRONT. ELEVATED HAILERS POSSIBLE NORTH OF THE FRONT THIS EVENING AS UPDRAFTS TAP SOME WARM MOIST UNSTABLE AIR FEEDING OVER THE BOUNDARY. MAY BE DIFFICULT TO GET SB INITIATION ALONG THE WARM FRONT...BUT IS MOST LIKELY IN THE AREA OF STRONGEST CONVERGENCE OVER THE FAR SOUTHWEST CWA. IF SB CONVECTION CAN DEVELOP...ALL PARAMETERS POINT TO SUPERCELLS WITH LOW LEVEL THERMODYNAMICS WOULD ALLOW FOR ISOLATED TORNADOES. OTHERWISE EXPECT LLJ TO KICK IN AND FEED A SEVERE MCS OVERNIGHT. HEAVY RAIN THREAT IS FAIRLY HIGH OVER OVER THE NORTHERN AND EASTERN CWA. WILL NOT ISSUE FLOOD WATCH DUE TO THE LACK OF HEAVY RAIN OVER THE THAT AREA OVER THE LAST COUPLE OF WEEKS. THUNDERSTORMS WILL EXIT THE CWA TO THE EAST WEDNESDAY MORNING AND WILL CONTINUE MORNING POPS. THEN QUESTION TURNS TO REDEVELOPMENT IN THE AFTERNOON ALONG THE BOUNDARY. FEEL AT THIS TIME IT IS UNLIKELY. WARMING MID LEVEL TEMPS AND LITTLE IF ANY UPPER SUPPORT WILL KEEP THINGS IN CHECK. WILL GO DRY DURING THE DAY TOMORROW. TOMORROW NIGHT EXPECT A MCS TO DEVELOP OVER THE WESTERN HIGH PLAINS AND TRACK TO THE SOUTHEAST DURING THE NIGHT. WILL RUN PRETTY HIGH POPS TOMORROW NIGHT AND ALSO MENTION HEAVY RAIN WITH PWATS OVER 2 INCHES. MAY HAVE TO CONSIDER A FLOOD WATCH FOR TOMORROW NIGHT IN THE SOUTHERN CWA WHERE MORE HEAVY RAIN HAS FALLEN OVER THE PAST COUPLE OF WEEKS. EXTENDED...LITTLE CHANGE TO THE EXTENDED. FEEL MRF IS RETROGRADING UPPER LOW OVER PAC NW TO MUCH...WITH A REX BLOCK DEVELOPING. THIS WILL ALLOW FOR UPPER HEIGHTS TO FALL OVER THE NORTHERN PLAINS BY THE END OF THE WEEK. THIS WILL ALLOW FOR THE ACTIVE SFC BOUNDARY TO SAG SOUTH OF THE AREA. WILL CONTINUE A DRY EXTENDED. OZF OUT BY 300 PM. THANKS FOR GREAT COORD FROM OMA AND MSP .FSD...NONE BOUSTEAD
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE SIOUX FALLS SD
828 PM CDT TUE AUG 20 2002
TIME(CDT) .....CITY LOCATION.....STATE ...EVENT/REMARKS...
....COUNTY LOCATION....
0732 PM 8 N PLANKINTON SD .75 INCH HAIL
08/20/02 AURORA REPORTED BY STORM
SPOTTER.
0735 PM 5 ESE LETCHER SD 1 INCH HAIL
08/20/02 SANBORN REPORTED BY STORM
SPOTTER.
0757 PM 7 NNW MT VERNON SD .75 INCH HAIL
08/20/02 DAVISON REPORTED BY STORM
SPOTTER.
0807 PM 8 NNE MT VERNON SD .88 INCH HAIL
08/20/02 DAVISON REPORTED BY STORM
SPOTTER.
0808 PM 1 N LOOMIS SD .75 INCH HAIL
08/20/02 DAVISON REPORTED BY STORM
SPOTTER.
0820 PM 5 SW MITCHELL SD 1.75 INCH HAIL
08/20/02 DAVISON REPORTED BY STORM
SPOTTER.PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE SIOUX FALLS SD
1000 PM CDT TUE AUG 20 2002
TIME(CDT) .....CITY LOCATION.....STATE ...EVENT/REMARKS...
....COUNTY LOCATION....
0255 PM 6 NE WHITE SD .75 INCH HAIL
08/20/02 BROOKINGS REPORTED BY PUBLIC.
0732 PM 8 N PLANKINTON SD .75 INCH HAIL
08/20/02 AURORA REPORTED BY STORM
SPOTTER.
0735 PM 5 ESE LETCHER SD 1 INCH HAIL
08/20/02 SANBORN REPORTED BY STORM
SPOTTER.
0757 PM 7 NNW MT VERNON SD .75 INCH HAIL
08/20/02 DAVISON REPORTED BY STORM
SPOTTER.
0807 PM 8 NNE MT VERNON SD .88 INCH HAIL
08/20/02 DAVISON REPORTED BY STORM
SPOTTER.
0808 PM 1 N LOOMIS SD .75 INCH HAIL
08/20/02 DAVISON REPORTED BY STORM
SPOTTER.
0820 PM 5 SW MITCHELL SD 1.75 INCH HAIL
08/20/02 DAVISON REPORTED BY STORM
SPOTTER.
0847 PM 2 S MITCHELL SD .88 INCH HAIL
08/20/02 DAVISON REPORTED BY STORM
SPOTTER.
0855 PM ALEXANDRIA SD 60 MPH TSTM GUST
08/20/02 HANSON REPORTED BY STORM
SPOTTER.
0915 PM 1 NE SPENCER SD 65 MPH TSTM GUST
08/20/02 MCCOOK REPORTED BY STORM
SPOTTER.
0935 PM STICKNEY SD .75 INCH HAIL
08/20/02 AURORA REPORTED BY STORM
SPOTTER.
0937 PM 3 S EMERY SD TORNADO
08/20/02 HANSON REPORTED BY STORM CHASER
0947 PM CORSICA SD 1 INCH HAIL
08/20/02 DOUGLAS REPORTED BY LAW
ENFORCEMENT OFFICIAL.The Sioux Falls radar (KFSD), 114 km away, was scanning. The volume nearest the first event began at 02:59 UTC.
1 flash flood. Local standard time, as filed.
Heavy rain caused flooding of a county road and of a nearby basement.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in South Dakota in 2002Every state in 2002This day in weather historyWarnings in South Dakota, 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: 5317614.