Clusters of severe thunderstorms...producing large hail up to 1.75 inches in diameter and wind gusts up to 70 mph (61 knots) moved across much of Southeast Wisconsin and a portion of South-Central Wisconsin during the afternoon hours of May 3rd. The thunderstorms developed in the warm sector ahead of low pressure over southeast Minnesota and behind a warm front that extended from the low across central Wisconsin. The unstable atmosphere, with mixed layer CAPE of 1500 to 2000 J/kg, and 0-6 km bulk shear around 40 knots was supportive of supercell thunderstorms. Wet conditions due to heavy rain associated with the thunderstorms led to a multi-vehicle accident on Interstate 94 near Lake Mills In Jefferson County, injuring (indirectly-related) two of the drivers.

Hail in JEFFERSON, WISCONSIN
From 03-MAY-12 12:40:00 to 03-MAY-12 12:40:00 (CST-6)
Location: LAKE MILLS
Magnitude: 1.25 
Reported by: Trained Spotter

Hail in JEFFERSON, WISCONSIN
From 03-MAY-12 12:41:00 to 03-MAY-12 12:41:00 (CST-6)
Location: LAKE MILLS
Magnitude: 1.00 
Reported by: Fire Department/Rescue

Hail in JEFFERSON, WISCONSIN
From 03-MAY-12 13:23:00 to 03-MAY-12 13:23:00 (CST-6)
Location: LAKE MILLS
Magnitude: 1.25 
Reported by: Trained Spotter

Hail in JEFFERSON, WISCONSIN
From 03-MAY-12 12:15:00 to 03-MAY-12 12:25:00 (CST-6)
Location: WATERTOWN
Magnitude: 1.25 
Reported by: Trained Spotter

Thunderstorm Wind in WASHINGTON, WISCONSIN
From 01-MAY-12 13:15:00 to 01-MAY-12 13:16:00 (CST-6)
Location: GERMANTOWN
Magnitude: 61.00 MG
Property damage: 3.00K
Reported by: Trained Spotter

Hail in JEFFERSON, WISCONSIN
From 03-MAY-12 12:48:00 to 03-MAY-12 12:48:00 (CST-6)
Location: JOHNSON CREEK
Magnitude: 1.00 
Reported by: NWS Employee

Hail in JEFFERSON, WISCONSIN
From 03-MAY-12 12:55:00 to 03-MAY-12 12:55:00 (CST-6)
Location: JOHNSON CREEK
Magnitude: 0.88 
Reported by: Public

Hail in JEFFERSON, WISCONSIN
From 03-MAY-12 13:02:00 to 03-MAY-12 13:02:00 (CST-6)
Location: SULLIVAN
Magnitude: 1.00 
Reported by: Public

Hail in DODGE, WISCONSIN
From 03-MAY-12 13:18:00 to 03-MAY-12 13:18:00 (CST-6)
Location: LEBANON
Magnitude: 1.00 
Reported by: Broadcast Media

Hail in WASHINGTON, WISCONSIN
From 01-MAY-12 13:23:00 to 01-MAY-12 13:23:00 (CST-6)
Location: GERMANTOWN
Magnitude: 1.75 
Reported by: Trained Spotter

Hail in WASHINGTON, WISCONSIN
From 01-MAY-12 13:15:00 to 01-MAY-12 13:15:00 (CST-6)
Location: HOLY HILL
Magnitude: 0.75 
Reported by: Trained Spotter

Hail in WAUKESHA, WISCONSIN
From 01-MAY-12 13:00:00 to 01-MAY-12 13:00:00 (CST-6)
Location: OCONOMOWOC
Magnitude: 1.50 
Reported by: Law Enforcement

Hail in WAUKESHA, WISCONSIN
From 01-MAY-12 13:00:00 to 01-MAY-12 13:00:00 (CST-6)
Location: OCONOMOWOC
Magnitude: 0.75 
Reported by: NWS Employee

Hail in WAUKESHA, WISCONSIN
From 01-MAY-12 13:14:00 to 01-MAY-12 13:14:00 (CST-6)
Location: OCONOMOWOC
Magnitude: 1.00 
Reported by: NWS Employee

Hail in DODGE, WISCONSIN
From 01-MAY-12 15:04:00 to 01-MAY-12 15:04:00 (CST-6)
Location: JUNEAU
Magnitude: 1.25 
Reported by: Trained Spotter

Hail in JEFFERSON, WISCONSIN
From 01-MAY-12 15:27:00 to 01-MAY-12 15:27:00 (CST-6)
Location: FT ATKINSON
Magnitude: 1.75 
Reported by: Public

Thunderstorm Wind in MILWAUKEE, WISCONSIN
From 01-MAY-12 13:28:00 to 01-MAY-12 13:28:00 (CST-6)
Location: RIVER HILLS
Magnitude: 57.00 MG
Property damage: 2.00K
Reported by: Broadcast Media

Hail in SAUK, WISCONSIN
From 01-MAY-12 09:00:00 to 01-MAY-12 09:00:00 (CST-6)
Location: WEST BARABOO
Magnitude: 1.00 
Reported by: Public