A short wave moving up the leading flank of an elongated large-scale trough that extended from the Upper Mississippi River Valley to the Central Plains provided large-scale lift for thunderstorm development over southern Wisconsin. A warm front extended across central Wisconsin back to surface low pressure over west-central Minnesota. This placed southern Wisconsin in a warm humid air mass, with temperatures in the 80's and dew points in the lower 70's producing CAPE values reaching 2000 J/kg. Deep-layer shear profiles were favorable for supercells as well as multicell line segments that produced damaging wind gusts. The thunderstorm winds caused widespread tree and power line damage. WE energies reported 23,000 customers were without power.

Thunderstorm Wind in FOND DU LAC, WISCONSIN
From 20-AUG-10 16:30:00 to 20-AUG-10 16:30:00 (CST-6)
Location: CAMPBELLSPORT
Magnitude: 70.00 EG
Reported by: Law Enforcement

Law enforcement officials reported shingles blown off a home and tree damage by thunderstorm wind gusts estimated at 70 knots (81 mph).

Thunderstorm Wind in FOND DU LAC, WISCONSIN
From 20-AUG-10 16:10:00 to 20-AUG-10 16:10:00 (CST-6)
Location: EDEN
Magnitude: 50.00 EG
Property damage: 75.00K
Reported by: Law Enforcement

Law enforcement officials reported a 100-year old barn was blown down by thunderstorm wind gusts estimated at 50 knots (58 mph).

Thunderstorm Wind in GREEN LAKE, WISCONSIN
From 20-AUG-10 16:30:00 to 20-AUG-10 16:30:00 (CST-6)
Location: DALTON
Magnitude: 56.00 EG
Reported by: Emergency Manager

The Green Lake County emergency manager reported tree damage caused by thunderstorm wind gusts estimated at 56 knots (65 mph).

Thunderstorm Wind in GREEN LAKE, WISCONSIN
From 20-AUG-10 14:07:00 to 20-AUG-10 14:15:00 (CST-6)
Location: BERLIN
Magnitude: 50.00 EG
Property damage: 100.00K
Crop damage: 2.00K
Reported by: County Official

County officials reported a tree fell through a house in Berlin. Power lines were reported down by the strong thunderstorm gusts, as well as minor crop damage.

Thunderstorm Wind in GREEN, WISCONSIN
From 20-AUG-10 14:35:00 to 20-AUG-10 14:35:00 (CST-6)
Location: BRODHEAD
Magnitude: 50.00 EG
Reported by: Law Enforcement

County sheriff deputies reported trees and power lines were blown down by the strong thunderstorm gusts.

Thunderstorm Wind in ROCK, WISCONSIN
From 20-AUG-10 14:45:00 to 20-AUG-10 14:50:00 (CST-6)
Location: DOWNTOWN JANESVILLE
Magnitude: 50.00 MG
Reported by: Law Enforcement

County sheriff deputies reported trees and power lines were blown down by the strong thunderstorm gusts. The AWOS at Janesville airport recorded a 58 mph (50 knot) wind gust at 345 pm CDT.

Thunderstorm Wind in DANE, WISCONSIN
From 20-AUG-10 14:57:00 to 20-AUG-10 15:05:00 (CST-6)
Location: STOUGHTON
Magnitude: 50.00 EG
Reported by: Law Enforcement

County sheriff deputies reported trees and power lines were blown down by the strong thunderstorm gusts.

Thunderstorm Wind in JEFFERSON, WISCONSIN
From 20-AUG-10 15:15:00 to 20-AUG-10 15:15:00 (CST-6)
Location: FT ATKINSON
Magnitude: 50.00 EG
Reported by: Law Enforcement

County sheriff deputies reported trees were blown down by the strong thunderstorm gusts.

Thunderstorm Wind in SHEBOYGAN, WISCONSIN
From 20-AUG-10 16:25:00 to 20-AUG-10 16:25:00 (CST-6)
Location: RANDOM LAKE
Magnitude: 56.00 EG
Reported by: Fire Department/Rescue

Fire officials reported tree damage by thunderstorm wind gusts estimated at 56 knots (65 mph).

Thunderstorm Wind in SHEBOYGAN, WISCONSIN
From 20-AUG-10 16:30:00 to 20-AUG-10 16:30:00 (CST-6)
Location: WALDO
Magnitude: 56.00 EG
Reported by: Fire Department/Rescue

Fire officials reported tree damage by thunderstorm wind gusts estimated at 56 knots (65 mph).

Thunderstorm Wind in SHEBOYGAN, WISCONSIN
From 20-AUG-10 16:40:00 to 20-AUG-10 16:40:00 (CST-6)
Location: SHEBOYGAN FALLS
Magnitude: 56.00 EG
Reported by: Fire Department/Rescue

Fire officials reported tree damage by thunderstorm wind gusts estimated at 56 knots (65 mph).

Thunderstorm Wind in JEFFERSON, WISCONSIN
From 20-AUG-10 15:25:00 to 20-AUG-10 15:30:00 (CST-6)
Location: LAKE MILLS
Magnitude: 50.00 EG
Reported by: Law Enforcement

County sheriff deputies reported trees were blown down by the strong thunderstorm gusts.

Thunderstorm Wind in SHEBOYGAN, WISCONSIN
From 20-AUG-10 16:45:00 to 20-AUG-10 16:45:00 (CST-6)
Location: HOWARDS GROVE
Magnitude: 56.00 EG
Reported by: Fire Department/Rescue

Fire officials reported tree damage by thunderstorm wind gusts estimated at 56 knots (65 mph).

Thunderstorm Wind in OZAUKEE, WISCONSIN
From 20-AUG-10 16:38:00 to 20-AUG-10 16:38:00 (CST-6)
Location: PORT WASHINGTON
Magnitude: 56.00 EG
Reported by: Law Enforcement

Law enforcement officials reported tree damage by thunderstorm wind gusts estimated at 56 knots (65 mph).

Thunderstorm Wind in JEFFERSON, WISCONSIN
From 20-AUG-10 14:45:00 to 20-AUG-10 15:30:00 (CST-6)
Location: WHITEWATER
Magnitude: 50.00 EG
Reported by: Law Enforcement

County sheriff deputies reported trees were blown down in and around the city of Whitewater to just west of Palmyra by the strong thunderstorm gusts. The damage was produced by three separate storms that trained over the area. There was also urban flooding in Whitewater and Palmyra caused by 2 inches of rain that fell in 45 minutes.

Thunderstorm Wind in GREEN LAKE, WISCONSIN
From 20-AUG-10 16:40:00 to 20-AUG-10 16:42:00 (CST-6)
Location: GREEN LAKE
Magnitude: 87.00 EG
Reported by: NWS Storm Survey

Based on a report from county emergency managers, an NWS storm survey team determined damage located near the northeast shore of Green Lake was caused by microburst winds estimated at 100 mph (81 knots). Eight homes, a boat and two piers were damaged by the winds. Four dozen trees were uprooted or snapped along the path of the microburst winds.

Thunderstorm Wind in SAUK, WISCONSIN
From 20-AUG-10 15:18:00 to 20-AUG-10 15:18:00 (CST-6)
Location: LA VALLE
Magnitude: 50.00 EG
Reported by: Law Enforcement

County sheriff deputies reported trees were blown down by the strong thunderstorm gusts.

Thunderstorm Wind in DODGE, WISCONSIN
From 20-AUG-10 15:40:00 to 20-AUG-10 15:40:00 (CST-6)
Location: LOWELL
Magnitude: 50.00 EG
Reported by: Law Enforcement

County sheriff deputies reported trees were blown down in the Lowell area by the strong thunderstorm gusts.

Thunderstorm Wind in WALWORTH, WISCONSIN
From 20-AUG-10 16:30:00 to 20-AUG-10 16:30:00 (CST-6)
Location: WALWORTH
Magnitude: 50.00 EG
Property damage: 25.00K
Reported by: Emergency Manager

The Walworth County Emergency Manager reported a pole barn was partially damaged by thunderstorm winds estimated at 50 knots (58 mph).

Thunderstorm Wind in DODGE, WISCONSIN
From 20-AUG-10 15:50:00 to 20-AUG-10 15:50:00 (CST-6)
Location: HORICON
Magnitude: 50.00 EG
Reported by: Law Enforcement

County sheriff deputies reported trees were blown down by the strong thunderstorm gusts.

Thunderstorm Wind in WAUKESHA, WISCONSIN
From 20-AUG-10 15:28:00 to 20-AUG-10 15:28:00 (CST-6)
Location: STONEBANK
Magnitude: 50.00 EG
Reported by: Law Enforcement

County sheriff deputies reported trees were blown down by the strong thunderstorm gusts.

Thunderstorm Wind in WALWORTH, WISCONSIN
From 20-AUG-10 16:37:00 to 20-AUG-10 16:41:00 (CST-6)
Location: DELAVAN
Magnitude: 50.00 EG
Property damage: 25.00K
Reported by: Emergency Manager

The Walworth County Emergency Manager reported tree damage caused by thunderstorm winds estimated at 50 knots (58 mph).

Thunderstorm Wind in JEFFERSON, WISCONSIN
From 20-AUG-10 15:36:00 to 20-AUG-10 15:36:00 (CST-6)
Location: OAK HILL
Magnitude: 50.00 MG
Reported by: Official NWS Observations

The peak thunderstorm wind gust of 58 mph (50 knots) measured at the National Weather Service office southeast of Sullivan.

Thunderstorm Wind in WAUKESHA, WISCONSIN
From 20-AUG-10 16:00:00 to 20-AUG-10 16:00:00 (CST-6)
Location: PEWAUKEE
Magnitude: 56.00 MG
Reported by: Trained Spotter

The peak thunderstorm wind gust of 65 mph (56 knots) measured by a trained spotter.

Thunderstorm Wind in WASHINGTON, WISCONSIN
From 20-AUG-10 15:45:00 to 20-AUG-10 15:45:00 (CST-6)
Location: SLINGER
Magnitude: 53.00 MG
Reported by: Mesonet

The peak thunderstorm wind gust of 61 mph (53 knots) was measured at a mesonet site in Slinger.

Thunderstorm Wind in WASHINGTON, WISCONSIN
From 20-AUG-10 16:01:00 to 20-AUG-10 16:01:00 (CST-6)
Location: WEST BEND
Magnitude: 64.00 MG
Reported by: Mesonet

The peak thunderstorm wind gust of 74 mph (64 knots) was measured by a trained spotter in West Bend.

Thunderstorm Wind in SHEBOYGAN, WISCONSIN
From 20-AUG-10 15:52:00 to 20-AUG-10 16:00:00 (CST-6)
Location: OOSTBURG
Magnitude: 52.00 EG
Reported by: Law Enforcement

County Sheriff deputies reported tree damage due to thunderstorm wind gusts along a path from Oostburg to the city of Sheboygan. The Sheboygan C-MAN observation site  at the harbor recorded a 49 knot (56 mph) wind gust at 5 pm CDT.

Thunderstorm Wind in MARQUETTE, WISCONSIN
From 20-AUG-10 16:10:00 to 20-AUG-10 16:10:00 (CST-6)
Location: OXFORD
Magnitude: 56.00 EG
Reported by: Amateur Radio

An amateur radio operator reported tree damage and power lines blown down onto a home in Oxford by thunderstorm wind gusts estimated at 56 knots (65 mph).

Thunderstorm Wind in COLUMBIA, WISCONSIN
From 20-AUG-10 16:25:00 to 20-AUG-10 16:25:00 (CST-6)
Location: PARDEEVILLE
Magnitude: 56.00 EG
Reported by: Emergency Manager

The Columbia County emergency manager reported tree damage caused by thunderstorm wind gusts estimated at 56 knots (65 mph).