Thunderstorms developed in the early evening of September 4th in an unstable air mass over the region with lift from an upper-level disturbance that moved across the western Great Lakes region ahead of a stronger wave in the Northern Plains.  CAPE values of 2000 J/kg to 2500 J/kg and 0-6 km bulk shear around 30 knots was sufficient to produce favorable conditions for sustained updrafts.  These factors produced clusters of severe thunderstorms that developed along a weak convergent boundary that extended from northeast Minnesota through western Wisconsin.  The clusters of supercell thunderstorms produced damaging wind gusts over a good portion of South-Central and Southeast Wisconsin.

Thunderstorm Wind in GREEN, WISCONSIN
From 04-SEP-12 19:20:00 to 04-SEP-12 19:30:00 (CST-6)
Location: NEW GLARUS
Magnitude: 56.00 EG
Property damage: 5.00K
Reported by: Law Enforcement

Law enforcement officials reported trees were blown down by damaging thunderstorm wind gusts estimated to be 56 knots (65 mph) along a path from New Glarus to 7 miles east of Dayton.

Thunderstorm Wind in DANE, WISCONSIN
From 04-SEP-12 19:24:00 to 04-SEP-12 19:24:00 (CST-6)
Location: STOUGHTON
Magnitude: 56.00 EG
Property damage: 2.00K
Reported by: Amateur Radio

A HAM radio operator reported trees and large branches were blown down by damaging thunderstorm wind gusts estimated to be 56 knots (65 mph) 2 miles south-southwest of Stoughton.

Thunderstorm Wind in JEFFERSON, WISCONSIN
From 04-SEP-12 19:31:00 to 04-SEP-12 19:31:00 (CST-6)
Location: LAKE MILLS
Magnitude: 56.00 EG
Property damage: 8.00K
Reported by: 911 Call Center

The Jefferson County 911 Call Center reported trees and power lines were blown down by damaging thunderstorm wind gusts estimated to be 56 knots (64 mph) in Lake Mills.

Thunderstorm Wind in ROCK, WISCONSIN
From 04-SEP-12 19:35:00 to 04-SEP-12 19:35:00 (CST-6)
Location: EVANSVILLE
Magnitude: 56.00 EG
Property damage: 4.00K
Reported by: Trained Spotter

A trained spotter reported trees were blown down by damaging thunderstorm wind gusts estimated to be 56 knots (64 mph) along a path from Evansville to 5 miles east-northeast of Milton.

Thunderstorm Wind in DANE, WISCONSIN
From 04-SEP-12 19:39:00 to 04-SEP-12 19:39:00 (CST-6)
Location: STOUGHTON
Magnitude: 56.00 EG
Property damage: 2.00K
Reported by: Trained Spotter

A trained spotter reported trees were blown down by damaging thunderstorm wind gusts estimated to be 56 knots (65 mph) 1 mile northeast of Stoughton.

Thunderstorm Wind in JEFFERSON, WISCONSIN
From 04-SEP-12 19:53:00 to 04-SEP-12 19:53:00 (CST-6)
Location: FT ATKINSON
Magnitude: 52.00 EG
Property damage: 2.00K
Reported by: Trained Spotter

A trained spotter reported trees were blown down by damaging thunderstorm wind gusts estimated to be 52 knots (60 mph) 1 mile east of Fort Atkinson.

Thunderstorm Wind in DANE, WISCONSIN
From 04-SEP-12 19:10:00 to 04-SEP-12 19:10:00 (CST-6)
Location: SUN PRAIRIE
Magnitude: 56.00 EG
Property damage: 5.00K
Reported by: Public

The public reported trees were blown down by damaging thunderstorm wind gusts estimated at 56 knots (65 mph) 2 miles west of Sun Prairie.

Thunderstorm Wind in DANE, WISCONSIN
From 04-SEP-12 19:12:00 to 04-SEP-12 19:12:00 (CST-6)
Location: CAMP RANDALL STADIUM
Magnitude: 52.00 EG
Property damage: 5.00K
Reported by: Public

The public reported large tree branches were blown down by damaging thunderstorm wind gusts estimated at 50 knots (60 mph) 1 mile northeast of Camp Randall Stadium in Madison.

Thunderstorm Wind in IOWA, WISCONSIN
From 04-SEP-12 19:05:00 to 04-SEP-12 19:12:00 (CST-6)
Location: EDMUND
Magnitude: 56.00 EG
Property damage: 10.00K
Reported by: Law Enforcement

Law enforcement officials reported trees and power lines were blown down by damaging thunderstorm wind gusts estimated at 56 knots (65 mph) along a path from Edmund to Dodgeville.

Thunderstorm Wind in IOWA, WISCONSIN
From 04-SEP-12 19:11:00 to 04-SEP-12 19:11:00 (CST-6)
Location: MINERAL POINT AIRPORT
Magnitude: 51.00 MG
Reported by: AWOS

Thunderstorm Wind in DANE, WISCONSIN
From 04-SEP-12 19:14:00 to 04-SEP-12 19:14:00 (CST-6)
Location: (MSN)TRUAX FLD MADIS
Magnitude: 50.00 MG
Reported by: ASOS

Thunderstorm Wind in COLUMBIA, WISCONSIN
From 04-SEP-12 19:05:00 to 04-SEP-12 19:15:00 (CST-6)
Location: PORTAGE
Magnitude: 56.00 EG
Property damage: 15.00K
Reported by: Law Enforcement

Law enforcement officials reported trees were blown down by damaging thunderstorm wind gusts estimated at 56 knots (65 mph) in an 5-mile wide swath from Portage to Pardeeville.

Thunderstorm Wind in LAFAYETTE, WISCONSIN
From 04-SEP-12 19:50:00 to 04-SEP-12 19:50:00 (CST-6)
Location: DARLINGTON
Magnitude: 56.00 EG
Property damage: 2.00K
Reported by: Law Enforcement

Law enforcement officials reported trees were blown down by damaging thunderstorm wind gusts estimated at 56 knots (65 mph) 7 miles northeast of Darlington.

Thunderstorm Wind in LAFAYETTE, WISCONSIN
From 04-SEP-12 20:10:00 to 04-SEP-12 20:10:00 (CST-6)
Location: NEW DIGGING
Magnitude: 56.00 EG
Property damage: 2.00K
Reported by: Law Enforcement

Law enforcement officials reported trees were blown down by damaging thunderstorm wind gusts estimated at 56 knots (65 mph) in New Digging.

Thunderstorm Wind in WALWORTH, WISCONSIN
From 04-SEP-12 20:10:00 to 04-SEP-12 20:25:00 (CST-6)
Location: LA GRANGE
Magnitude: 56.00 EG
Property damage: 4.00K
Reported by: 911 Call Center

The Walworth County 911 Center received reports of trees blown down by damaging thunderstorm wind gusts estimated at 56 knots (65 mph) from La Grange to Delavan.

Thunderstorm Wind in WAUKESHA, WISCONSIN
From 04-SEP-12 20:05:00 to 04-SEP-12 20:10:00 (CST-6)
Location: EAGLE
Magnitude: 56.00 EG
Property damage: 3.00K
Reported by: 911 Call Center

The Waukesha County 911 Center received reports of trees blown down by damaging thunderstorm wind gusts estimated at 56 knots (65 mph) from 5 miles northwest of Eagle to Eagle.

Thunderstorm Wind in DODGE, WISCONSIN
From 04-SEP-12 19:35:00 to 04-SEP-12 19:35:00 (CST-6)
Location: LOWELL
Magnitude: 52.00 EG
Property damage: 10.00K
Reported by: Trained Spotter

A trained spotter reported trees and power lines blown down by damaging thunderstorm wind gusts estimated at 52 knots (60 mph) in Lowell.

Thunderstorm Wind in RACINE, WISCONSIN
From 04-SEP-12 20:29:00 to 04-SEP-12 20:40:00 (CST-6)
Location: TICHIGAN
Magnitude: 56.00 EG
Property damage: 10.00K
Reported by: 911 Call Center

The Racine County 911 Call Center reported trees and power lines blown down by damaging thunderstorm wind gusts estimated at 56 knots (65 mph) from Tichigan to Burlington.

Thunderstorm Wind in RACINE, WISCONSIN
From 04-SEP-12 20:35:00 to 04-SEP-12 20:35:00 (CST-6)
Location: WIND LAKE
Magnitude: 52.00 EG
Property damage: 5.00K
Reported by: Trained Spotter

A trained spotter reported trees and power lines blown down by damaging thunderstorm wind gusts estimated at 52 knots (60 mph) in Wind Lake.

Thunderstorm Wind in KENOSHA, WISCONSIN
From 04-SEP-12 20:40:00 to 04-SEP-12 20:50:00 (CST-6)
Location: WHEATLAND
Magnitude: 52.00 EG
Property damage: 5.00K
Reported by: Law Enforcement

Law enforcement officials reported trees were blown down by damaging thunderstorm wind gusts estimated at 52 knots (60 mph) along a Wheatland to Paris line.

Thunderstorm Wind in OZAUKEE, WISCONSIN
From 04-SEP-12 20:42:00 to 04-SEP-12 20:42:00 (CST-6)
Location: FREDONIA
Magnitude: 50.00 EG
Property damage: 3.00K
Reported by: Law Enforcement

Law enforcement officials reported trees were blown down by damaging thunderstorm wind gusts estimated at 50 knots (58 mph) in Fredonia.

Hail in LAFAYETTE, WISCONSIN
From 05-SEP-12 01:55:00 to 05-SEP-12 01:55:00 (CST-6)
Location: BELMONT
Magnitude: 0.75 
Reported by: Trained Spotter

Thunderstorm Wind in KENOSHA, WISCONSIN
From 04-SEP-12 20:52:00 to 04-SEP-12 20:52:00 (CST-6)
Location: BENET LAKE
Magnitude: 52.00 EG
Property damage: 5.00K
Reported by: Law Enforcement

Law enforcement officials reported were trees blown down by damaging thunderstorm wind gusts estimated at 60 mph (52 knots) 1.5 miles northeast of Benet Lake.

Thunderstorm Wind in SAUK, WISCONSIN
From 04-SEP-12 18:46:00 to 04-SEP-12 18:49:00 (CST-6)
Location: BARABOO
Magnitude: 56.00 EG
Property damage: 12.00K
Reported by: 911 Call Center

Sauk County 911 Call Center personnel reported trees and power lines were blown down by damaging thunderstorm wind gusts estimated at 56 knots (65 mph) along a path from 5 miles southeast of Baraboo to Merrimac.

Thunderstorm Wind in SAUK, WISCONSIN
From 04-SEP-12 18:40:00 to 04-SEP-12 18:45:00 (CST-6)
Location: ROCK SPGS
Magnitude: 56.00 EG
Property damage: 12.00K
Reported by: 911 Call Center

Sauk County 911 Call Center personnel reported trees and power lines were blown down by damaging thunderstorm wind gusts estimated at 56 knots (65 mph) along a path from 3 miles south of Rock Springs to 5 miles south-southwest of Baraboo.

Thunderstorm Wind in IOWA, WISCONSIN
From 04-SEP-12 18:55:00 to 04-SEP-12 18:55:00 (CST-6)
Location: AVOCA
Magnitude: 56.00 EG
Property damage: 4.00K
Reported by: Law Enforcement

Law enforcement officials reported trees were blown down by damaging thunderstorm wind gusts estimated at 56 knots (65 mph) 4 miles south-southwest of Avoca.

Thunderstorm Wind in COLUMBIA, WISCONSIN
From 04-SEP-12 19:00:00 to 04-SEP-12 19:20:00 (CST-6)
Location: OKEE
Magnitude: 56.00 EG
Property damage: 20.00K
Reported by: Law Enforcement

Law enforcement officials reported trees and power lines were blown down by damaging thunderstorm wind gusts estimated at 56 knots (65 mph) in an 8-mile wide swath from Harmony Grove to 5 miles east-southeast of Arlington.