A large complex of thunderstorms moved across northern Iowa during the early morning hours. The storms produced a strong outflow boundary to the south of them.
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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 episode as NWS DMX wrote it up.
A large complex of thunderstorms moved across northern Iowa during the early morning hours. The storms produced a strong outflow boundary to the south of them. Strong winds, generally 40 to 50 MPH, were common as the outflow boundary moved south. A wind gust of 61 MPH was recorded as the boundary moved through the Glidden area. Only minor damage occurred.
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 12, 1:54 AM CST, 1 hour 36 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DES MOINES IA 254 AM CDT MON AUG 12 2002 SEVERAL CONCERNS FOR THE NEXT 24 HOURS AS FRONT PROGRESSES THROUGH THE STATE. PRIMARY WOULD BE SEVERE THREAT ALONG WITH PSBL HEAVY RAINFALL. CURRENTLY...STRONG CONVECTION ACRS NORTHERN IA HAS HELD BELOW SVR CRITERIA. IT HAS PRODUCED AN OUTFLOW WHICH IS NOW LINING UP FROM WEST TO EAST ALONG HIGHWAY 20 AND SHOULD CONTINUE A SOUTHWARD DRIFT. LOW LEVEL INFLOW IS NEARLY PERPENDICULAR TO THIS BOUNDARY AND AM CONCERNED ABOUT TRAINING FOR THE NEXT FEW HOURS. WITH PLENTY OF MOISTURE (PW FROM 1.5 TO 2.0 INCHES) WL DEFINITELY ADD MENTION FOR HEAVY RAINS. FOR TODAY...FRONTAL BOUNDARY WL BEGIN TO SLIDE ACRS THE CWA BY LATE MORNING AND SLOWLY PROGRESS EAST DURING THE AFTERNOON. AMOUNT OF RESIDUAL CONVECTION AND CLOUD COVER WL PLAY A BIG ROLE IN DESTABILIZATION TODAY. EXPECT TSRA TO BE ONGOING OR MOVE INTO THE NORTHWEST THIRD TO HALF BY MIDDAY AND THIS SHOULD KEEP HEATING DOWN SOME. HOWEVER...SOUTHEAST SHOULD WARM NICELY WITH CAPES AOA 2000 J/KG. THIS WL BE SUFFICIENT INSTABILITY TO REDEVELOP AND/OR INTENSIFY MORNING CONVECTION. WNDS APPEAR TO BE THE PRIMARY SVR THREAT AS SOME FORM OF LINEAR COMPLEX DEVELOPS...HOWEVER HAIL MAY ALSO OCCUR. ONGOING STORMS WL PERSIST INTO THE OVERNIGHT BUT WL BE ENDING FROM NORTHWEST TO SOUTHEAST DURING THE NIGHT AS DRIER AIR SLOWLY PUSHES INTO THE STATE. SOME RESIDUAL SHOWERS CONTINUE TO BE POSSIBLE IN THE FAR SOUTHEAST ON TUESDAY...HOWEVER SUBSIDENCE FARTHER NORTHWEST SHOULD PROVIDE DRYING FOR MUCH OF THE CWA. TEMPS WL ALSO BE A GOOD 10 DEGREES COOLER. APPEARS LATER PERIODS ARE IN DECENT SHAPE WITH LITTLE CHANGE TO ZONES. .DSM...NONE COGIL
The national radar mosaic for the moment the first event began.
1 high wind. Local standard time, as filed.
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: 5311776.