July 27, 2006 Heavy Rain / Flash Flooding

SLOW MOVING THUNDERSTORMS OVER THREE SEPARATE AREAS PRODUCED TORRENTIAL RAINFALL AND LOCALIZED FLASH FLOODING DURING THE AFTERNOON. THESE AREAS ARE OUTLINED BELOW ALONG WITH THE ASSOCIATED AFFECTS.

1. THE FIRST AREA OCCURRED OVER THE MADISON METROPOLITAN AREA WHERE 3 TO 5 INCHES OF RAIN WAS ESTIMATED BY NATIONAL WEATHER SERVICE DOPPLER RADAR. TORRENTIAL RAIN IN THE CITY OF MADISON...NEAR THE UNIVERSITY OF WISCONSIN CAMPUS...CAUSED AREAS OF FLASH FLOODING WHERE CARS WERE REPORTED FLOATING AND WATER WAS REPORTED UP TO ROOFS OF OTHER VEHICLES.

2. ANOTHER AREA OF HEAVY RAIN WAS LOCATED OVER SOUTHERN DANE COUNTY...BETWEEN VERONA AND BELLEVILLE. RADAR ESTIMATED 4 TO 6 INCHES OF RAIN FELL IN THIS AREA.

3. THE THIRD AREA WAS LOCATED OVER CENTRAL WAUKESHA COUNTY...IN AND AROUND THE CITY OF WAUKESHA. RADAR ESTIMATED 4 TO 6 INCHES OF RAIN IN THIS AREA AS WELL. IN WAUKESHA...THE PEWAUKEE RIVER NEAR HIGHWAY 164 FLOODED IT/S BANKS AND CAUSED THE HIGHWAY TO CLOSE. THE FOX RIVER IN DOWNTOWN WAUKESHA ALSO EXCEEDED FLOOD STAGE FOR A COUPLE HOURS AFTER A RAPID RISE IN RIVER LEVELS. IN OTHER PORTIONS OF THE CITY...FLOODED STREETS AND CREEKS CAUSED MAJOR INCONVENIENCES TO AREA RESIDENTS.

SOME STORMS RESPONSIBLE FOR CAUSING THE FLOODING...ALSO PRODUCED DAMAGING WINDS AND A FEW FUNNEL CLOUDS. TREES AND POWER LINES WERE REPORTED DOWN NEAR WAUKESHA AS WELL AS MADISON...EAGLE...WATERFORD... AND UNION GROVE DUE TO HIGH THUNDERSTORM WINDS. FUNNEL CLOUDS WERE REPORTED IN STOUGHTON...WAUWATOSA...AND BROOKFIELD.

THE EXCESSIVE RAINFALL AND FLOODING RESULTED FROM THE DEVELOPMENT OF VERY SLOW MOVING...OR NEARLY STATIONARY...SCATTERED SHOWERS AND THUNDERSTORMS IN A WARM AND VERY MOIST AIRMASS. HOURLY RAINFALL RATES OF 1 TO 3 INCHES PER HOUR PERSISTED OVER A FEW LOCATIONS FOR A PROLONGED PERIOD OF TIME...ALLOWING FOR RAPID ACCUMULATION OF RAIN WATER.

Radar Estimate

Radar Estimate Of Rainfall

The hand-drawn rainfall maps below are based on data from official co-op observers, ASOS, amateur radio operators, severe weather spotters, Madison TV-15 school network sites, reports from Madison TV-3 and TV-27, people from the general public, and the NWS's WSR-88D Doppler radar rainfall estimates. For the most part, the radar rainfall estimates were fairly close to the observed rainfall amounts. Therefore, the hand analysis utilized the radar rainfall estimates in those areas where observed rainfall amounts were not available. The hand analysis is to be considered unofficial - it is our best "guess" as to how much rain fell. There was an unofficial report of more than 5 inches of rain on the west side of Madison, but the amount reports differed significantly from close proximity surrounding reports. Therefore, this one report (West of West High School) was not used in the hand analysis.

Dane County

Waukesha County

Coop Observations

Pictures of flooding in Madison