A strong cold front swept across Wisconsin, being driven by an amplifying short wave trough moving east from the Plains, that produced a strong area of low pressure north of Lake Superior.  The front interacted with a warm and unstable air mass, with CAPE values between 1500 J/kg and 2000 J/kg, bringing severe thunderstorms to southern Wisconsin in the late afternoon and early evening hours.  Strong deep layer shear led to the development of a line of thunderstorms with damaging wind gusts.  Heavy rain with the thunderstorms produced 1 to 2 inch per hour rainfall amounts that briefly flooded streets and parking lots, especially on the southwest side of Madison, Verona and Fitchburg in Dane County.  The heavy downpours and lightning forced officials to cancel a cross country meet in DeForest, also in Dane County.  There were also a few reports of near-severe nickel-sized hail.

Thunderstorm Wind in IOWA, WISCONSIN
From 02-SEP-10 16:20:00 to 02-SEP-10 16:20:00 (CST-6)
Location: MINERAL PT
Magnitude: 56.00 EG
Reported by: Law Enforcement

Sheriff deputies reported 5 to 6 large trees were blown down by strong thunderstorm wind gusts estimated at 56 knots (65 mph) north of Mineral Point on Union Ridge.

Thunderstorm Wind in DANE, WISCONSIN
From 02-SEP-10 17:32:00 to 02-SEP-10 17:35:00 (CST-6)
Location: STOUGHTON
Magnitude: 56.00 EG
Property damage: 1.00K
Reported by: Trained Spotter

A trained spotter reported trees blown down by strong thunderstorm wind gusts estimated at 56 knots (65 mph) along a path from Stoughton to Deerfield.  A 3-foot diameter tree fell on a truck in Stoughton.  Damage amount is estimated.

Thunderstorm Wind in JEFFERSON, WISCONSIN
From 02-SEP-10 17:40:00 to 02-SEP-10 17:45:00 (CST-6)
Location: LAKE MILLS
Magnitude: 56.00 EG
Reported by: Law Enforcement

Sheriff deputies reported trees blown down by strong thunderstorm wind gusts estimated at 56 knots (65 mph) along a line from Lake Mills to Oakland Township.

Thunderstorm Wind in JEFFERSON, WISCONSIN
From 02-SEP-10 17:49:00 to 02-SEP-10 17:49:00 (CST-6)
Location: JEFFERSON
Magnitude: 56.00 EG
Reported by: NWS Employee

A National Weather Service employee reported a thunderstorm wind gust estimated at 56 knots (65 mph).

Thunderstorm Wind in WASHINGTON, WISCONSIN
From 02-SEP-10 18:00:00 to 02-SEP-10 18:15:00 (CST-6)
Location: HARTFORD
Magnitude: 65.00 EG
Property damage: 20.00K
Reported by: Fire Department/Rescue

Fire officials reported trees blown down and damage to the roofs of two commercial buildings near Hartford by thunderstorm wind gusts estimated at 65 knots (75 mph).  Damage amount is estimated.

Thunderstorm Wind in WAUKESHA, WISCONSIN
From 02-SEP-10 18:15:00 to 02-SEP-10 18:20:00 (CST-6)
Location: NASHOTAH
Magnitude: 70.00 EG
Reported by: Law Enforcement

Law enforcement officials reported trees and power lines blown down by thunderstorm wind gusts estimated at 70 knots (81 mph).

Thunderstorm Wind in OZAUKEE, WISCONSIN
From 02-SEP-10 18:35:00 to 02-SEP-10 18:35:00 (CST-6)
Location: SAUKVILLE
Magnitude: 65.00 EG
Reported by: Emergency Manager

The Ozaukee County Emergency Manager reported trees blown down by thunderstorm wind gusts estimated at 65 knots (75 mph). Two houses had siding damage from the gusty winds, with one home having a brick facade peeled away.

Hail in WAUKESHA, WISCONSIN
From 02-SEP-10 18:02:00 to 02-SEP-10 18:02:00 (CST-6)
Location: OCONOMOWOC
Magnitude: 0.88 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: NWS Employee

Hail in WAUKESHA, WISCONSIN
From 02-SEP-10 18:15:00 to 02-SEP-10 18:15:00 (CST-6)
Location: OCONOMOWOC
Magnitude: 0.88 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter