Iowa, 2002

Flash Flooding in Iowa, May 8, 2002

May 8, 2002 · NWS ARX · 4 events in 3 counties and zones

Thunderstorms produced 4 inches of rain in about an hour, causing flash flooding. Law enforcement officials reported numerous roads washed out, while 1 to 2 feet of water covered roads in Waukon (Allamakee County) and Protivin (Howard County).

Where it happened

Every event with a place to put it; 4 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
$80,000
Crop damage
None recorded
Events
4

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 ARX wrote it up.

Thunderstorms produced 4 inches of rain in about an hour, causing flash flooding. Law enforcement officials reported numerous roads washed out, while 1 to 2 feet of water covered roads in Waukon (Allamakee County) and Protivin (Howard County). Some farmers reported substantial losses to cattle in flooded river bottoms near Village Creek (Allamakee County).

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 La Crosse, WI wrote its last area forecast discussion before the first event at May 8, 2:32 PM CST, 3 hours 28 minutes earlier.

Area forecast discussion, May 8, 2:32 PM CST, 3 hours 28 minutes before
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
332 PM CDT WED MAY 8 2002

...SEVERE WEATHER THREAT ACROSS MUCH OF THE AREA TONIGHT...

THE MAIN FORECAST CONCERN WITH THIS PACKAGE DEALS WITH THE SEVERE WEATHER
THREAT FOR TONIGHT...AND STRONG WINDS FOR THURSDAY.

AT 3 PM...A STRENGTHENING SURFACE LOW WAS LOCATED OVER NORTHWEST IOWA.
BOTH THE ETA AND AVN MODELS HAVE THIS LOW POORLY INITIALIZED. THEY TEND
TO DEVELOP THE LOW OVER KANSAS AS THE MAIN LOW AND IGNORE THIS LOW.
HOWEVER...LOOKING AT THE SURFACE DEW POINTS...THE NORTHERN LOW WILL BE
THE MORE SIGNIFICANT OF THESE LOW PRESSURE AREAS. BY LOOKING AT THE
SURFACE DEW POINTS IT WOULD SUGGEST THAT THIS LOW WILL TRACK TOWARD
THE TWIN CITIES THIS EVENING. BREEZY SOUTH AND SOUTHEAST WINDS
ACROSS SOUTHEAST MINNESOTA...NORTHEAST IOWA...AND SOUTHWEST
WISCONSIN HAVE INCREASED THE SURFACE DEW POINTS INTO THE UPPER 50S
AND LOWER 60S. IN ADDITION...SUNSHINE THIS AFTERNOON HAS CAUSED
TEMPERATURES TO CLIMB INTO THE MIDDLE 70S ACROSS SOUTHEAST MINNESOTA
AND AROUND 80 IN NORTHEAST IOWA. SATELLITE SOUNDER DATA INDICATES
THAT THE LIFTED INDICES HAVE FALLEN TO -8 OVER NORTH CENTRAL IOWA AND
THE CAPES HAVE INCREASED TO AROUND 1500 J/KG ACROSS NORTHEAST IOWA.
FROM LOOKING AT THE BLUE RIVER PROFILER...THERE IS PLENTY OF SPEED
AND DIRECTIONAL SHEAR. AS A RESULT...I EXPECT THE THUNDERSTORMS TO
FORM INITIALLY AS SUPERCELLS AND EVENTUALLY EVOLVE INTO A SQUALL
LINE THIS EVENING. THE INITIAL THREAT OF SEVERE WEATHER APPEARS TO
BE LARGE HAIL AND POTENTIALLY SOME ISOLATED TORNADOES...AND THEN
EVOLVE INTO A DAMAGING WIND EVENT.

AS THE LOW CONTINUES TO STRENGTHEN DURING THE DAY THURSDAY...THE
PRESSURE GRADIENT WILL CONTINUE TO INCREASE ACROSS THE COUNTY
WARNING AREA. IN ADDITION...THE AREA WILL SEE STRONG SUBSIDENCE
BEHIND THE SHORT WAVE. THE 1000 MB TO 850 MB LAPSE RATES ARE
MARGINAL FOR ADVECTING THE REALLY STRONG WINDS FROM ALOFT TO THE
SURFACE. AS A RESULT...THE WINDS WILL NOT BE QUITE AS STRONG AS THEY
COULD GET. HOWEVER...THE SUSTAINED WIND SPEEDS WILL LIKELY STILL BE
IN THE 25 TO 35 MPH RANGE IN SOUTHEAST MINNESOTA AND NORTHEAST
IOWA...AND IN THE 20 TO 30 MPH RANGE ACROSS THE REMAINDER OF THE
AREA. WIND GUSTS WILL BE LIKELY AROUND 45 MPH. CONSIDERING ALL THAT
IS GOING ON TONIGHT...I DIDNT ISSUE A WIND ADVISORY AT THIS TIME...
BUT ONE MAY BE NEEDED FOR THURSDAY IF THE LAPSE RATES GET ANY
STEEPER.

.LSE...NONE.

BOYNE

In the hours before

Special weather statement, May 8, 5:21 PM CST, 39 minutes before
WATCH COUNTY NOTIFICATION FOR WATCH #74
NATIONAL WEATHER SERVICE LA CROSSE WI
621 PM CDT WED MAY 8 2002

IAC005-037-043-065-089-191-MNC045-055-109-157-169-WIC011-019-023-043-
053-057-063-081-103-121-123-090400-

THE NATIONAL WEATHER SERVICE HAS ISSUED A TORNADO WATCH UNTIL 1100
PM CDT WEDNESDAY EVENING FOR THE FOLLOWING AREAS:

IN IOWA THIS WATCH INCLUDES 6 COUNTIES...
IN NORTHEAST NORTHEAST IOWA:

ALLAMAKEE             CHICKASAW             CLAYTON
FAYETTE               HOWARD                WINNESHIEK

IN MINNESOTA THIS WATCH INCLUDES 5 COUNTIES...
IN SOUTHEAST SOUTHEAST MINNESOTA:

FILLMORE              HOUSTON               OLMSTED
WABASHA               WINONA

IN WISCONSIN THIS WATCH INCLUDES 11 COUNTIES...
IN CENTRAL CENTRAL WISCONSIN:

CLARK                 JUNEAU

IN SOUTHWEST SOUTHWEST WISCONSIN:

CRAWFORD              GRANT                 RICHLAND
VERNON

IN WEST CENTRAL WEST CENTRAL WISCONSIN:

BUFFALO               JACKSON               LA CROSSE
MONROE                TREMPEALEAU

THIS INCLUDES THE CITIES OF ALMA...ARCADIA...BLACK RIVER FALLS...
CALEDONIA...CRESCO...DECORAH...ELKADER...GUTTENBERG...LA CRESCENT...
LA CROSSE...LAKE CITY...LANCASTER...LANSING...MAUSTON...MONDOVI...
NEILLSVILLE...NEW HAMPTON...OELWEIN...PLATTEVILLE...PRAIRIE DU
CHIEN...PRESTON...RICHLAND CENTER...ROCHESTER...SPARTA...TOMAH...
VIROQUA...WABASHA...WAUKON...WEST UNION...WHITEHALL AND WINONA.
Local storm report, May 8, 5:28 PM CST, 32 minutes before
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE LA CROSSE WI
628 PM CDT WED MAY 8 2002

TIME(CDT)  .....CITY LOCATION.....STATE   ...EVENT/REMARKS...
           ....COUNTY LOCATION....

618 PM     ROCHESTER                 MN   1 INCH HAIL
05/08/02   OLMSTED                        REPORTED BY THE PUBLIC.

SHEA
Local storm report, May 8, 5:35 PM CST, 25 minutes before
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE LA CROSSE WI
635 PM CDT WED MAY 8 2002

TIME(CDT)  .....CITY LOCATION.....STATE   ...EVENT/REMARKS...
           ....COUNTY LOCATION....

620 PM     2 S DOUGLAS               MN   1 INCH HAIL
05/08/02   OLMSTED                        REPORTED BY PUBLIC.

SHEA
Local storm report, May 8, 5:48 PM CST, 12 minutes before
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE LA CROSSE WI
648 PM CDT WED MAY 8 2002

TIME(CDT)  .....CITY LOCATION.....STATE   ...EVENT/REMARKS...
           ....COUNTY LOCATION....

0633 PM    ROCHESTER                 MN   1.25 INCH HAIL
05/08/02   OLMSTED                        REPORTED BY PUBLIC ON
                                          NORTHEAST SIDE OF
                                          ROCHESTER.

SHEA
Local storm report, May 8, 5:52 PM CST, 8 minutes before
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE LA CROSSE WI
652 PM CDT WED MAY 8 2002

TIME(CDT)  .....CITY LOCATION.....STATE   ...EVENT/REMARKS...
           ....COUNTY LOCATION....

0651 PM    PROTIVIN                  IA   .75 INCH HAIL
05/08/02   HOWARD                         REPORTED BY HAM RADIO
                                          SPOTTERS. DIME SIZE HAIL.

SHEA
Local storm report, May 8, 5:59 PM CST, 1 minute before
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE LA CROSSE WI
659 PM CDT WED MAY 8 2002

TIME(CDT)  .....CITY LOCATION.....STATE   ...EVENT/REMARKS...
           ....COUNTY LOCATION....

0658 PM    3 S PROTIVIN              IA   TORNADO
05/08/02   CHICKASAW                      REPORTED BY SPOTTERS.

SHEA

The radar

The national radar mosaic for the moment the first event began.

Open the radar archive at this moment

Event by event

4 flash flood. Local standard time, as filed.

Flash Flood, Howard

When
May 8, 6:00 PM CST to 7:25 PM CST
Where
Howard County, Protivin
Property damage
$25,000
Reported by
AMATEUR RADIO
Coordinates
43.357, -92.317 (the zone’s center; the record gives no point)

Flash Flood, Winneshiek

When
May 8, 6:29 PM CST to 7:45 PM CST
Where
Winneshiek County, Ridgeway
Property damage
$8,000
Reported by
LAW ENFORCEMENT
Coordinates
43.291, -91.844 (the zone’s center; the record gives no point)

Flash Flood, Winneshiek

When
May 8, 6:45 PM CST to 8:00 PM CST
Where
Winneshiek County, Decorah
Property damage
$12,000
Reported by
LAW ENFORCEMENT
Coordinates
43.291, -91.844 (the zone’s center; the record gives no point)

Flash Flood, Allamakee

When
May 8, 8:00 PM CST to 10:30 PM CST
Where
Allamakee County, Waukon
Property damage
$35,000
Reported by
LAW ENFORCEMENT
Coordinates
43.284, -91.378 (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

More

Every storm in Iowa in 2002Every state in 2002This day in weather historyWarnings in Iowa, May 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: 5294371, 5294372, 5294373, 5294374.