Several lines of severe thunderstorms crossed southern Wisconsin during the evening hours of May 14th. The storms produced damaging wind gusts up to 70 to 75 mph (60 to 65 knots). Widespread damage was reported in swaths up to 6 miles in width, which included structural damage to homes and farm buildings as well as downed trees and power lines due to the powerful winds. WE Energies reported 23,000 customers in Dodge, Jefferson, Waukesha and Milwaukee counties were without power at the height of the storm. The severe thunderstorms formed along a warm front that extended from weak low pressure in northwest Wisconsin south of Superior to near Chicago. While wind shear and instability were marginal, evaporative cooling as the rain fell into dry air in the lower levels produced prime conditions for downbursts.

Thunderstorm Wind in DANE, WISCONSIN
From 14-MAY-13 19:00:00 to 14-MAY-13 19:22:00 (CST-6)
Location: ROXBURY
Magnitude: 65.00 EG
Property damage: 100.00K
Reported by: Fire Department/Rescue

Firefighters reported numerous trees, power lines and some power poles downed by thunderstorm wind gusts, estimated at 75 mph (65 knots), along a 5-mile wide path from 2 miles northwest of Roxbury to 2.5 miles east of Marshall. An old barn was completely blown down; a shed was moved 4 feet off of it's foundation; and roof shingles, siding and downspouts were torn off of a couple of homes in the village of Dane.

Thunderstorm Wind in DODGE, WISCONSIN
From 14-MAY-13 19:23:00 to 14-MAY-13 19:38:00 (CST-6)
Location: PORTLAND
Magnitude: 61.00 EG
Property damage: 10.00K
Reported by: Newspaper

Newspaper articles indicated numerous trees and power lines downed by thunderstorm wind gusts, estimated at 70 mph (61 knots) along a path from 2 miles north of Portland to 3 miles east of Ashippun.

Thunderstorm Wind in JEFFERSON, WISCONSIN
From 14-MAY-13 19:20:00 to 14-MAY-13 19:40:00 (CST-6)
Location: WATERLOO
Magnitude: 65.00 EG
Property damage: 100.00K
Reported by: Public

The public reported numerous trees and power lines downed by thunderstorm wind gusts estimated at 75 mph (65 knots). The damage, in a 6-mile wide swath from 2 miles south of Waterloo to 2.5 miles east of Ixonia, included the destruction of a large pole barn, which had 4-inch by 4-inch support posts ripped out of the ground by the winds.  Other homes, barns and sheds were reported to be damaged by the severe thunderstorm wind gusts.

Thunderstorm Wind in MILWAUKEE, WISCONSIN
From 14-MAY-13 20:02:00 to 14-MAY-13 20:25:00 (CST-6)
Location: WAUWATOSA
Magnitude: 61.00 EG
Property damage: 50.00K
Reported by: Trained Spotter

A trained spotter reported numerous trees and power lines downed by thunderstorm wind gusts estimated up to 70 mph (61 knots) along a path from 2 miles west of Wauwatosa to just east of Cudahy. A downed power line sparked a house fire 3 miles southwest of downtown Milwaukee.

Thunderstorm Wind in ROCK, WISCONSIN
From 14-MAY-13 20:55:00 to 14-MAY-13 21:15:00 (CST-6)
Location: CLINTON
Magnitude: 61.00 EG
Property damage: 10.00K
Reported by: Law Enforcement

Law enforcement officials indicated numerous trees and power lines downed by thunderstorm wind gusts, estimated at 70 mph (61 knots), along a path from 3 miles west-northwest of Clinton to 3 miles southeast of Clinton.

Thunderstorm Wind in WAUKESHA, WISCONSIN
From 14-MAY-13 19:40:00 to 14-MAY-13 20:00:00 (CST-6)
Location: OCONOMOWOC
Magnitude: 59.00 MG
Property damage: 30.00K
Reported by: Law Enforcement

Law enforcement officials reported numerous trees and power lines downed by thunderstorm wind gusts, measured by a trained spotter at 68 mph (59 knots). The damage was reported along an 8-mile wide swath from 1.5 miles west of Oconomowoc to 1 mile east of Elm Grove.