Strong to severe thunderstorms developed as lift associated with a 500 mb short wave moved into southern Wisconsin. The short wave eroded a cap on a moist and unstable air mass, with mixed-layer CAPE values of 2,000 to 3,000 J/KG, and enough deep-layer shear for sustained updrafts. There were numerous reports of large hail in the 1 to 2 inch range with the severe thunderstorms, with 4-inch hail reported in Jefferson County. While no specific damage reports were made to officials, the Jefferson County Emergency Management Director stated some properties might have received damage from the large hail, such as dents to vehicles.

Hail in WAUKESHA, WISCONSIN
From 11-MAY-11 15:30:00 to 11-MAY-11 15:30:00 (CST-6)
Location: HARTLAND
Magnitude: 2.00 
Reported by: Trained Spotter

Hail in WAUKESHA, WISCONSIN
From 11-MAY-11 15:44:00 to 11-MAY-11 15:44:00 (CST-6)
Location: HARTLAND
Magnitude: 1.25 
Reported by: NWS Employee

Hail in GREEN, WISCONSIN
From 11-MAY-11 15:38:00 to 11-MAY-11 15:38:00 (CST-6)
Location: MONROE
Magnitude: 1.00 
Reported by: Emergency Manager

Hail in DANE, WISCONSIN
From 11-MAY-11 15:54:00 to 11-MAY-11 15:54:00 (CST-6)
Location: COTTAGE GROVE
Magnitude: 0.88 
Reported by: Trained Spotter

Hail in DANE, WISCONSIN
From 11-MAY-11 16:01:00 to 11-MAY-11 16:01:00 (CST-6)
Location: DOWNTOWN MADISON
Magnitude: 0.75 
Reported by: Trained Spotter

Hail in DANE, WISCONSIN
From 11-MAY-11 12:36:00 to 11-MAY-11 12:36:00 (CST-6)
Location: DOWNTOWN MADISON
Magnitude: 1.00 
Reported by: Trained Spotter

Hail in DANE, WISCONSIN
From 11-MAY-11 12:41:00 to 11-MAY-11 12:41:00 (CST-6)
Location: (MSN)TRUAX FLD MADIS
Magnitude: 1.00 
Reported by: Trained Spotter

Hail in DANE, WISCONSIN
From 11-MAY-11 12:43:00 to 11-MAY-11 12:43:00 (CST-6)
Location: (MSN)TRUAX FLD MADIS
Magnitude: 1.00 
Reported by: Trained Spotter

Hail in DANE, WISCONSIN
From 11-MAY-11 12:47:00 to 11-MAY-11 12:47:00 (CST-6)
Location: (MSN)TRUAX FLD MADIS
Magnitude: 1.50 
Reported by: Trained Spotter

Hail in DANE, WISCONSIN
From 11-MAY-11 13:00:00 to 11-MAY-11 13:00:00 (CST-6)
Location: MC FARLAND
Magnitude: 2.00 
Reported by: Public

Hail in DANE, WISCONSIN
From 11-MAY-11 13:28:00 to 11-MAY-11 13:28:00 (CST-6)
Location: SUN PRAIRIE
Magnitude: 1.00 
Reported by: Amateur Radio

Hail in DANE, WISCONSIN
From 11-MAY-11 13:30:00 to 11-MAY-11 13:30:00 (CST-6)
Location: LONDON
Magnitude: 1.00 
Reported by: Trained Spotter

Hail in JEFFERSON, WISCONSIN
From 11-MAY-11 13:34:00 to 11-MAY-11 13:34:00 (CST-6)
Location: JEFFERSON
Magnitude: 4.25 
Reported by: Emergency Manager

Hail in JEFFERSON, WISCONSIN
From 11-MAY-11 13:40:00 to 11-MAY-11 13:43:00 (CST-6)
Location: JEFFERSON
Magnitude: 2.00 
Reported by: NWS Employee

Hail in RACINE, WISCONSIN
From 11-MAY-11 16:55:00 to 11-MAY-11 16:55:00 (CST-6)
Location: BOHNERS LAKE
Magnitude: 0.88 
Reported by: Trained Spotter

Hail in JEFFERSON, WISCONSIN
From 11-MAY-11 13:40:00 to 11-MAY-11 13:40:00 (CST-6)
Location: JOHNSON CREEK
Magnitude: 2.75 
Reported by: Public

Report from the public of baseball-sized hail that broke windows on homes and vehicles.

Hail in DANE, WISCONSIN
From 11-MAY-11 15:08:00 to 11-MAY-11 15:08:00 (CST-6)
Location: VERONA
Magnitude: 1.25 
Reported by: Amateur Radio

Hail in DANE, WISCONSIN
From 11-MAY-11 15:28:00 to 11-MAY-11 15:28:00 (CST-6)
Location: DOWNTOWN MADISON
Magnitude: 1.25 
Reported by: Trained Spotter

Hail in DANE, WISCONSIN
From 11-MAY-11 15:38:00 to 11-MAY-11 15:38:00 (CST-6)
Location: DOWNTOWN MADISON
Magnitude: 0.75 
Reported by: Trained Spotter

Hail in WAUKESHA, WISCONSIN
From 11-MAY-11 15:37:00 to 11-MAY-11 15:37:00 (CST-6)
Location: HARTLAND
Magnitude: 1.00 
Reported by: Amateur Radio

Hail in DANE, WISCONSIN
From 11-MAY-11 15:45:00 to 11-MAY-11 15:45:00 (CST-6)
Location: MONONA
Magnitude: 1.75 
Reported by: Trained Spotter

Hail in DANE, WISCONSIN
From 11-MAY-11 15:50:00 to 11-MAY-11 15:50:00 (CST-6)
Location: COTTAGE GROVE
Magnitude: 1.00 
Reported by: Trained Spotter

Hail in DANE, WISCONSIN
From 11-MAY-11 12:43:00 to 11-MAY-11 12:43:00 (CST-6)
Location: MC FARLAND
Magnitude: 1.00 
Reported by: Trained Spotter

Hail in DANE, WISCONSIN
From 11-MAY-11 12:45:00 to 11-MAY-11 12:45:00 (CST-6)
Location: DOWNTOWN MADISON
Magnitude: 1.25 
Reported by: Trained Spotter

Hail in JEFFERSON, WISCONSIN
From 11-MAY-11 13:26:00 to 11-MAY-11 13:26:00 (CST-6)
Location: FT ATKINSON
Magnitude: 1.75 
Reported by: Law Enforcement

Hail in DANE, WISCONSIN
From 11-MAY-11 15:30:00 to 11-MAY-11 15:30:00 (CST-6)
Location: MIDDLETON
Magnitude: 0.75 
Reported by: Trained Spotter