An upper level short wave trough moved rapidly eastward across the Upper Mississippi River Valley and into Wisconsin during the early morning hours of August 9th. The approaching short wave backed low level winds to the south, which brought a moist, unstable air mass into the region with CAPE values of 2000 to 3000 J/kg. A linear mesoscale convective system developed over Nebraska and moved eastward across northern Iowa on the nose of the 30-35 knot low-level winds. This system moved into Wisconsin shortly after 1 am CDT, with the bowing line of storms producing damaging winds along a 10-mile-wide path as it moved rapidly from west to east across South Central and Southeast Wisconsin. The line of thunderstorms extensively damaged trees and downed power lines, including knocking out electrical power to 1,300 Alliant Energy customers in eastern Sauk County and northwest Dane County. Madison Gas and Electric Company reported about 4,000 of their customers lost power on the southwest side of Madison.

Thunderstorm Wind in WAUKESHA, WISCONSIN
From 09-AUG-10 02:30:00 to 09-AUG-10 02:40:00 (CST-6)
Location: DOUSMAN
Magnitude: 56.00 EG
Reported by: Law Enforcement

Police officials reported trees and power lines blown down from damaging thunderstorm wind gusts estimated at 56 knots (65 mph).

Thunderstorm Wind in MILWAUKEE, WISCONSIN
From 09-AUG-10 03:00:00 to 09-AUG-10 03:00:00 (CST-6)
Location: MILWAUKEE TIMMERMAN AIRPORT
Magnitude: 54.00 EG
Reported by: Law Enforcement

Police officials reported trees blown down from damaging thunderstorm wind gusts. A mesonet site on the campus of Divine Savior-Holy Angels High School measured a thunderstorm wind gust of 62 mph (54 knots) at 4 am CDT.

Thunderstorm Wind in IOWA, WISCONSIN
From 09-AUG-10 00:45:00 to 09-AUG-10 00:45:00 (CST-6)
Location: DODGEVILLE
Magnitude: 56.00 EG
Reported by: Law Enforcement

Sheriff deputies reported large trees were blown down by thunderstorm wind gusts estimated up to 56 knots (65 mph).

Thunderstorm Wind in IOWA, WISCONSIN
From 09-AUG-10 01:03:00 to 09-AUG-10 01:03:00 (CST-6)
Location: MINERAL PT
Magnitude: 56.00 EG
Reported by: Law Enforcement

Sheriff deputies reported large trees down over many locations across eastern Iowa County from damaging thunderstorm wind gusts.

Thunderstorm Wind in DANE, WISCONSIN
From 09-AUG-10 01:26:00 to 09-AUG-10 01:26:00 (CST-6)
Location: VERONA
Magnitude: 65.00 EG
Property damage: 10.00K
Reported by: Law Enforcement

Sheriff deputies reported large trees and power lines blown down from damaging thunderstorm wind gusts estimated at 65 knots (75 mph).

Thunderstorm Wind in DANE, WISCONSIN
From 09-AUG-10 01:34:00 to 09-AUG-10 01:34:00 (CST-6)
Location: MIDDLETON
Magnitude: 65.00 EG
Property damage: 2.00K
Reported by: Law Enforcement

Sheriff deputies reported large trees blown down from damaging thunderstorm wind gusts estimated at 65 knots (75 mph). A large tree fell on a house in the 7000 block of Sagebrush Trail, resulting in minor damage.

Thunderstorm Wind in SAUK, WISCONSIN
From 09-AUG-10 01:00:00 to 09-AUG-10 01:10:00 (CST-6)
Location: LOGANVILLE
Magnitude: 65.00 EG
Reported by: Law Enforcement

Sheriff deputies reported extensive trees damage from thunderstorm wind gusts estimated at 65 knots (75 mph).

Thunderstorm Wind in COLUMBIA, WISCONSIN
From 09-AUG-10 01:25:00 to 09-AUG-10 01:33:00 (CST-6)
Location: LODI
Magnitude: 65.00 EG
Reported by: Law Enforcement

Sheriff deputies reported sporadic damage to large trees from damaging thunderstorm wind gusts estimated at 65 knots (75 mph).

Thunderstorm Wind in MARQUETTE, WISCONSIN
From 09-AUG-10 01:30:00 to 09-AUG-10 01:30:00 (CST-6)
Location: WESTFIELD
Magnitude: 56.00 EG
Reported by: Law Enforcement

Sheriff deputies reported damage to large trees from thunderstorm wind gusts estimated at 56 knots (64 mph).

Thunderstorm Wind in COLUMBIA, WISCONSIN
From 09-AUG-10 01:52:00 to 09-AUG-10 02:10:00 (CST-6)
Location: RIO
Magnitude: 56.00 EG
Reported by: Law Enforcement

Sheriff deputies reported sporadic tree damage from thunderstorm wind gusts estimated at 56 knots (65 mph).

Thunderstorm Wind in ROCK, WISCONSIN
From 09-AUG-10 01:55:00 to 09-AUG-10 02:05:00 (CST-6)
Location: EDGERTON
Magnitude: 65.00 EG
Reported by: Law Enforcement

Police officials reported tree damage and building damage from thunderstorm wind gusts estimated at 65 knots (75 mph).

Thunderstorm Wind in JEFFERSON, WISCONSIN
From 09-AUG-10 02:00:00 to 09-AUG-10 02:10:00 (CST-6)
Location: LAKE MILLS
Magnitude: 65.00 EG
Reported by: Law Enforcement

Police officials reported considerable tree damage from thunderstorm wind gusts estimated at 65 knots (75 mph).

Thunderstorm Wind in WASHINGTON, WISCONSIN
From 09-AUG-10 02:50:00 to 09-AUG-10 02:55:00 (CST-6)
Location: WEST BEND
Magnitude: 56.00 EG
Reported by: Law Enforcement

Police officials reported considerable tree damage from thunderstorm wind gusts estimated at 56 knots (65 mph). The AWOS at West Bend airport recorded a 60 mph (52 knot) wind gust at 350 am CDT.