Three rounds of thunderstorms produced wind damage and flash flooding during the afternoon, evening, and overnight hours of August 9th.  The thunderstorms developed as a cold front trailing from low pressure over northeast Wisconsin moved into a hot, humid and unstable air mass in place over southern Wisconsin.  Temperatures warmed to 85 and 90 degrees, with dew-points in the 70s.  Strong unidirectional vertical wind shear produced bowing line segments that caused damaging wind gusts.  The thunderstorms produced heavy rainfall as precipitable water values reached 1.8 to 2 inches.  All together, in just southeast Wisconsin, at least 28,000 customers lost electrical power.  It was reported that 140 power-lines came down due to tree debris, and at least a dozen or two utility poles snapped.

Flash Flood in ROCK, WISCONSIN
From 09-AUG-09 14:00:00 to 09-AUG-09 16:00:00 (CST-6)
Location: DOWNTOWN JANESVILLE
Flood cause: Heavy Rain
Property damage: 30.00K
Crop damage: 0.00K
Reported by: Emergency Manager

Heavy rain caused significant street flooding and basement flooding in the city of Janesville.  Fast-flowing water depths of 1 to 3 feet were noted on some roads and water damage to basement contents was noted.

Thunderstorm Wind in WALWORTH, WISCONSIN
From 09-AUG-09 14:32:00 to 09-AUG-09 14:41:00 (CST-6)
Location: EAST TROY
Magnitude: 57.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Tree damage from near Beulah Station (east of city of East Troy) to Honey Creek was noted by a trained spotter.  Based on the size of the limbs and trees blown down they estimated winds in excess of 52 knots (60 mph).

Thunderstorm Wind in WALWORTH, WISCONSIN
From 09-AUG-09 14:30:00 to 09-AUG-09 14:30:00 (CST-6)
Location: LAKE GENEVA
Magnitude: 65.00 EG
Property damage: 15.00K
Crop damage: 0.00K
Reported by: Public

Numerous public reports were made of trees blown down and power lines down in the city of Lake Geneva.

Thunderstorm Wind in LAFAYETTE, WISCONSIN
From 09-AUG-09 14:55:00 to 09-AUG-09 15:07:00 (CST-6)
Location: YELLOWSTONE LAKE STATE PARK
Magnitude: 65.00 EG
Property damage: 50.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Law enforcement reported numerous trees and power lines down in a 3-mile wide swath over northeastern Lafayette County.  The damage swath extended north into Iowa County and east-northeast into the counties of Green and Dane.  Roof damage was also reported on several homes.  Outside of the city of Blancardville, a barn was blown down.

Thunderstorm Wind in ROCK, WISCONSIN
From 09-AUG-09 13:45:00 to 09-AUG-09 13:45:00 (CST-6)
Location: EVANSVILLE
Magnitude: 65.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Damaging thunderstorm winds gusts blew trees down over roads in the city of Evansville.

Thunderstorm Wind in ROCK, WISCONSIN
From 09-AUG-09 14:05:00 to 09-AUG-09 14:15:00 (CST-6)
Location: MILTON
Magnitude: 65.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Damaging thunderstorm wind gusts blew trees down over area roadways between Milton and Johnstown Center.

Thunderstorm Wind in IOWA, WISCONSIN
From 09-AUG-09 14:13:00 to 09-AUG-09 14:13:00 (CST-6)
Location: HIGHLAND
Magnitude: 65.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Law enforcement reported a number of trees blown down by strong thunderstorm wind gusts in and around the village of Highland.

Flash Flood in GREEN, WISCONSIN
From 09-AUG-09 13:15:00 to 09-AUG-09 15:30:00 (CST-6)
Location: MONROE
Flood cause: Heavy Rain
Property damage: 10.00K
Crop damage: 0.00K
Reported by: NWS Employee

A National Weather Service employee reported significant street flooding in the city of Monroe with water depths of 2 to 4 feet.  Some water damage to basement contents was noted.

Thunderstorm Wind in RACINE, WISCONSIN
From 09-AUG-09 14:45:00 to 09-AUG-09 15:10:00 (CST-6)
Location: WATERFORD
Magnitude: 75.00 EG
Property damage: 200.00K
Crop damage: 15.00K
Reported by: Law Enforcement

Numerous trees and power lines were blown down in a 10-mile damage swath from just west of Waterford to the city of Racine.  The FAA Terminal Doppler radar located in north-central Racine County about 5 miles east of the village of Wind Lake showed 85 knot winds at 250 feet above ground level.  In Waterford a large tree fell on and damaged a business building.  On the north side of Racine two power-poles came down.  Several homes in the swath lost varying amounts of roof shingles.  There were several reports of tree debris damaging home siding or portions of a roof.  Piers and docks were  lifted and twisted and damaged on Wind Lake.  About 3.5 miles southwest of the City of Racine a camper was lifted by the wind gusts  and slammed into a car.  A large section of a corn field near Caledonia was flattned by the winds.

Thunderstorm Wind in GREEN, WISCONSIN
From 09-AUG-09 15:07:00 to 09-AUG-09 15:13:00 (CST-6)
Location: POSTVILLE
Magnitude: 65.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Damage to trees and power lines was reported in a 6 mile wide swath from the Iowa County border to 5 miles west of New Glarus. This was a continuation of the line of thunderstorms that produced damage in southeast Iowa County. The length of the entire damage swath totaled about 10 miles.

Thunderstorm Wind in IOWA, WISCONSIN
From 09-AUG-09 14:55:00 to 09-AUG-09 15:07:00 (CST-6)
Location: BLANCHARDVILLE
Magnitude: 65.00 EG
Property damage: 50.00K
Crop damage: 0.00K
Reported by: Law Enforcement

A swath of thunderstorm wind damage occurred over southeast Iowa County.  This swath extended into northeastern Lafayette County and east/southeast into the counties of Dane and Green. Overall the swath was about 15 miles wide.  Numerous large trees were uprooted or large branches broken.  Tree debris brought down some power-lines.  Some roof shingles were blown off the roofs of a couple homes.

Thunderstorm Wind in GREEN, WISCONSIN
From 09-AUG-09 15:05:00 to 09-AUG-09 15:30:00 (CST-6)
Location: MONROE
Magnitude: 65.00 EG
Property damage: 15.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Police reported numerous trees and power lines blown down in a 10-mile wide swath. This was a separate thunderstorm cluster from the one that caused the damage near New Glarus.

Thunderstorm Wind in ROCK, WISCONSIN
From 09-AUG-09 15:30:00 to 09-AUG-09 15:30:00 (CST-6)
Location: ORFORDVILLE
Magnitude: 65.00 EG
Property damage: 10.00K
Crop damage: 0.00K
Reported by: Trained Spotter

A trained spotter reported toppled large trees and and power lines down in the village of Orfordville due to thunderstorm winds.

Flash Flood in LAFAYETTE, WISCONSIN
From 09-AUG-09 13:00:00 to 09-AUG-09 15:30:00 (CST-6)
Location: NEW DIGGING
Flood cause: Heavy Rain
Property damage: 20.00K
Crop damage: 50.00K
Reported by: Fire Department/Rescue

The Shullsburg Fire Department and trained spotters reported fast-flowing water covered roads up to 1.5 feet deep.  Also, gravel shoulders were washed out on a couple roads from the heavy rain in the area south and southwest of Shullsburg.  There were also reports of small stream flooding as well as flooding of farm fields that damaged some crops.

Thunderstorm Wind in LAFAYETTE, WISCONSIN
From 09-AUG-09 14:40:00 to 09-AUG-09 14:40:00 (CST-6)
Location: CALAMINE
Magnitude: 65.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Law enforcement reported trees blown down and blocking roads around Calamine in the civil township of Willow Springs, north of the city of Darlington.

Thunderstorm Wind in ROCK, WISCONSIN
From 09-AUG-09 15:45:00 to 09-AUG-09 15:55:00 (CST-6)
Location: MILTON
Magnitude: 68.00 MG
Property damage: 150.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Police reported numerous trees and power lines down between Milton and Janesville.  Roof damage was reported in Janesville from the thunderstorm wind gusts, and several homes were damaged by tree debris.  One home had some windows blown out.  Barn damage was noted in the countryside around Janesville.  A 68 knot (78 mph) wind gust was recorded at the Janesville Airport (KJVL).

Thunderstorm Wind in KENOSHA, WISCONSIN
From 09-AUG-09 15:05:00 to 09-AUG-09 15:20:00 (CST-6)
Location: DOWNTOWN KENOSHA
Magnitude: 65.00 EG
Property damage: 30.00K
Crop damage: 0.00K
Reported by: Emergency Manager

Thunderstorm winds left a 3-mile wide swath of damage through the City of Kenosha. Numerous trees were uprooted and tree debris knocked down several power-lines. Construction arricades and signs were blown around, and one stop sign was pushed over.

Lightning in RACINE, WISCONSIN
From 09-AUG-09 14:50:00 to 09-AUG-09 14:50:00 (CST-6)
Location: WATERFORD
Property damage: 20.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Lightning struck a business building and damaged all inside electronic equipment.

Lightning in WAUKESHA, WISCONSIN
From 09-AUG-09 23:30:00 to 09-AUG-09 23:30:00 (CST-6)
Location: NEW BERLIN
Property damage: 50.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Lightning struck a home and started a fire that resulted in a fair amount of damage.

Thunderstorm Wind in MILWAUKEE, WISCONSIN
From 09-AUG-09 15:05:00 to 09-AUG-09 15:05:00 (CST-6)
Location: OAK CREEK
Magnitude: 60.00 EG
Property damage: 15.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Numerous trees and power lines were blown down by thunderstorm wind gusts that were estimated at 61 knots (70 mph).  This was from the same line of thunderstorms that moved through northern Racine County.

Thunderstorm Wind in WAUKESHA, WISCONSIN
From 09-AUG-09 14:50:00 to 09-AUG-09 14:50:00 (CST-6)
Location: MUSKEGO
Magnitude: 61.00 EG
Property damage: 10.00K
Crop damage: 0.00K
Reported by: Broadcast Media

Powerful thunderstorm wind gusts toppled large trees and generated tree debris that brought down some power lines.

Thunderstorm Wind in WALWORTH, WISCONSIN
From 09-AUG-09 16:01:00 to 09-AUG-09 16:04:00 (CST-6)
Location: DELAVAN
Magnitude: 64.00 MG
Property damage: 25.00K
Crop damage: 0.00K
Reported by: Amateur Radio

Numerous trees and power lines were blown down by thunderstorm wind gusts.  The gusts were measured to 74 mph, with sustained winds of 59 mph, on weather equipment owned by a ham radio operator near Delavan.  A television meteorologist estimated wind gusts in Lake Geneva of 52 knots.

Thunderstorm Wind in RACINE, WISCONSIN
From 09-AUG-09 14:50:00 to 09-AUG-09 14:50:00 (CST-6)
Location: BURLINGTON
Magnitude: 61.00 EG
Property damage: 15.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Powerful thunderstorm winds toppled many large trees in the city of Burlington.  One tree had a vary large branch snap off and fall onto a car, curshing it in the process.  Tree debris brought down several power-lines.

Thunderstorm Wind in WAUKESHA, WISCONSIN
From 09-AUG-09 16:04:00 to 09-AUG-09 16:04:00 (CST-6)
Location: EAGLE
Magnitude: 56.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Police reported trees down in the village of Eagle with estimated wind gusts of 56 knots (65 mph).

Thunderstorm Wind in WAUKESHA, WISCONSIN
From 09-AUG-09 16:14:00 to 09-AUG-09 16:14:00 (CST-6)
Location: DOWNTOWN WAUKESHA
Magnitude: 52.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Trees were reported to be blown down by thunderstorm wind gusts on the southeast side of the city of Waukesha by a trained spotter.

Thunderstorm Wind in DANE, WISCONSIN
From 09-AUG-09 15:30:00 to 09-AUG-09 15:30:00 (CST-6)
Location: DANE
Magnitude: 56.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Large trees uprooted and large limbs were knocked out of trees by powerful gusts with heavy rains.

Thunderstorm Wind in DANE, WISCONSIN
From 09-AUG-09 15:07:00 to 09-AUG-09 15:10:00 (CST-6)
Location: DALEYVILLE
Magnitude: 65.00 EG
Property damage: 10.00K
Crop damage: 0.00K
Reported by: Emergency Manager

Emergency Management reported large trees and power lines down in extreme southwestern Dane County, south of Daleyville, along Drammen Valey Rd.  This damage was an extension of a damage swath that extended west into Iowa County and south-southwest into northwestern Green County and northeastern Lafayette County.

Thunderstorm Wind in MILWAUKEE, WISCONSIN
From 09-AUG-09 16:55:00 to 09-AUG-09 16:55:00 (CST-6)
Location: WAUWATOSA
Magnitude: 56.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Large trees were either uprooted or split by powerful thunderstorm wind gusts.