A line of scattered to broken supercell thunderstorms formed along a cold front that was slicing into a very warm, unstable air mass over the Upper Midwest. The combination of wind shear and CAPE provided ideal conditions for the supercells to congeal into a bowing mesoscale convective system that roared west to east across southern Wisconsin during the late evening hours of July 25th and early overnight hours of July 26th. Damaging wind gusts from the severe thunderstorm complex produced numerous reports of downed trees, power lines and some property damage to homes and businesses.

Thunderstorm Wind in FOND DU LAC, WISCONSIN
From 25-JUL-12 23:38:00 to 25-JUL-12 23:38:00 (CST-6)
Location: FOND DU LAC  AIRPORT
Magnitude: 62.00 MG
Reported by: ASOS

The ASOS at Fond Du Lac Airport measured a thunderstorm wind gust of 62 knots (71 mph).

Thunderstorm Wind in GREEN, WISCONSIN
From 25-JUL-12 23:33:00 to 25-JUL-12 23:33:00 (CST-6)
Location: MONROE AIRPORT
Magnitude: 56.00 MG
Reported by: AWOS

The AWOS at Monroe Airport measured a thunderstorm wind gust of 57 knots (64 mph).

Thunderstorm Wind in JEFFERSON, WISCONSIN
From 26-JUL-12 00:16:00 to 26-JUL-12 00:16:00 (CST-6)
Location: FT ATKINSON
Magnitude: 57.00 EG
Reported by: NWS Employee

An NWS employee reported trees, large branches and power lines blown down in Fort Atkinson by damaging thunderstorm wind gusts estimated at 57 knots (65 mph).

Thunderstorm Wind in JEFFERSON, WISCONSIN
From 26-JUL-12 00:30:00 to 26-JUL-12 00:39:00 (CST-6)
Location: PALMYRA
Magnitude: 55.00 MG
Reported by: Mesonet

Numerous trees were blown down along a path from 2 miles south of Palmyra to 2 miles north of Palmyra by damaging thunderstorm wind gusts measured at a mesonet site at 55 knots (63 mph).

Thunderstorm Wind in WAUKESHA, WISCONSIN
From 26-JUL-12 00:30:00 to 26-JUL-12 00:30:00 (CST-6)
Location: OCONOMOWOC
Magnitude: 61.00 EG
Reported by: NWS Employee

An NWS employee reported a trampoline was blown into a house window by damaging wind gusts estimated at 70 mph (61 knots).

Thunderstorm Wind in WAUKESHA, WISCONSIN
From 26-JUL-12 00:40:00 to 26-JUL-12 00:40:00 (CST-6)
Location: DELAFIELD
Magnitude: 61.00 EG
Property damage: 25.00K
Reported by: Newspaper

A local newspaper reported trees and power lines were downed  and a few homes damaged by severe thunderstorm wind gusts estimated at 70 mph (61 knots).

Thunderstorm Wind in JEFFERSON, WISCONSIN
From 26-JUL-12 00:40:00 to 26-JUL-12 00:40:00 (CST-6)
Location: SULLIVAN
Magnitude: 56.00 EG
Reported by: NWS Employee

An NWS employee reported a severe thunderstorm wind gust estimated at 65 mph (56 knots).

Thunderstorm Wind in FOND DU LAC, WISCONSIN
From 26-JUL-12 00:15:00 to 26-JUL-12 00:15:00 (CST-6)
Location: FOND DU LAC
Magnitude: 56.00 EG
Reported by: Trained Spotter

A trained spotter reported trees blown down by severe thunderstorm wind gusst estimated at 65 mph (56 knots).

Thunderstorm Wind in WAUKESHA, WISCONSIN
From 26-JUL-12 00:53:00 to 26-JUL-12 00:53:00 (CST-6)
Location: BIG BEND
Magnitude: 56.00 EG
Reported by: Public

The public reported an anchored gazebo was blown over by severe thunderstorm wind gusts estimated at 65 mph (56 knots).

Thunderstorm Wind in WAUKESHA, WISCONSIN
From 26-JUL-12 00:54:00 to 26-JUL-12 00:54:00 (CST-6)
Location: WAUKESHA CO ARPT
Magnitude: 51.00 MG
Reported by: AWOS

The AWOS at Waukesha County Airport (Crites Field) measured a severe thunderstorm wind gust of 59 mph (53 knots).

Thunderstorm Wind in WASHINGTON, WISCONSIN
From 26-JUL-12 00:53:00 to 26-JUL-12 00:53:00 (CST-6)
Location: RICHFIELD
Magnitude: 52.00 EG
Reported by: Storm Chaser

A storm chaser reported a large road sign was blown down by severe thunderstorm wind gusts estimated at 60 mph (52 knots).

Thunderstorm Wind in IOWA, WISCONSIN
From 25-JUL-12 22:40:00 to 25-JUL-12 22:40:00 (CST-6)
Location: AVOCA
Magnitude: 65.00 EG
Reported by: Law Enforcement

Law enforcement officials reported trees and power lines blown down along a swath from 5 miles west southwest of Avoca to Avoca by damaging thunderstorm wind gusts estimated up to 65 knots (70 mph).

Thunderstorm Wind in LAFAYETTE, WISCONSIN
From 25-JUL-12 23:03:00 to 25-JUL-12 23:03:00 (CST-6)
Location: DARLINGTON
Magnitude: 56.00 EG
Reported by: Law Enforcement

Law enforcement officials reported trees and power lines blown down in Darlington by damaging thunderstorm wind gusts estimated up to 56 knots (65 mph).

Thunderstorm Wind in LAFAYETTE, WISCONSIN
From 25-JUL-12 22:51:00 to 25-JUL-12 22:51:00 (CST-6)
Location: SHULLSBURG
Magnitude: 56.00 EG
Reported by: Law Enforcement

Law enforcement officials reported trees and power lines blown down in Shullsburg by damaging thunderstorm wind gusts estimated up to 56 knots (65 mph).

Thunderstorm Wind in LAFAYETTE, WISCONSIN
From 25-JUL-12 23:11:00 to 25-JUL-12 23:11:00 (CST-6)
Location: SOUTH WAYNE
Magnitude: 56.00 EG
Reported by: Law Enforcement

Law enforcement officials reported trees and power lines blown down in South Wayne by damaging thunderstorm wind gusts estimated up to 56 knots (65 mph).

Thunderstorm Wind in DODGE, WISCONSIN
From 25-JUL-12 23:08:00 to 25-JUL-12 23:08:00 (CST-6)
Location: FOX LAKE
Magnitude: 56.00 EG
Reported by: Law Enforcement

Law enforcement officials reported trees and a power pole were blown down in Fox Lake by damaging thunderstorm wind gusts estimated up to 56 knots (65 mph).

Thunderstorm Wind in LAFAYETTE, WISCONSIN
From 25-JUL-12 23:13:00 to 25-JUL-12 23:13:00 (CST-6)
Location: ARGYLE
Magnitude: 56.00 EG
Reported by: Law Enforcement

Law enforcement officials reported trees and a power pole were blown down in Argyle by damaging thunderstorm wind gusts estimated up to 56 knots (65 mph).

Thunderstorm Wind in SAUK, WISCONSIN
From 25-JUL-12 22:56:00 to 25-JUL-12 22:56:00 (CST-6)
Location: LONE ROCK AIRPORT
Magnitude: 55.00 MG
Reported by: ASOS

The ASOS at Lone Rock Airport measured a thunderstorm wind gust of 56 knots (55 mph).