A severe squall line rapidly moved east across southern WI in the vicinity of a stalled frontal boundary. Much of the severe weather was associated with a supercell thunderstorm on the southern end of the line. The supercell produced wind driven, large hail, damaging siding and windows of homes. The largest hail was around baseball size.

Hail in WALWORTH, WISCONSIN
From 02-MAY-18 19:55:00 to 02-MAY-18 19:55:00 (CST-6)
Location: WILLIAMS BAY
Magnitude: 1.25 
Crop damage: 0.00K
Reported by: Broadcast Media

Picture provided.

Hail in WAUKESHA, WISCONSIN
From 02-MAY-18 19:44:00 to 02-MAY-18 19:44:00 (CST-6)
Location: DOWNTOWN WAUKESHA
Magnitude: 1.00 
Crop damage: 0.00K
Reported by: Trained Spotter

Hail in ROCK, WISCONSIN
From 02-MAY-18 19:21:00 to 02-MAY-18 19:22:00 (CST-6)
Location: DOWNTOWN JANESVILLE
Magnitude: 1.50 
Property damage: 50.00K
Crop damage: 0.00K
Reported by: Public

Wind driven hail damaging siding, breaking windows, and tearing window screens in the Cedar Crest neighborhood and surrounding neighborhoods.

Hail in WALWORTH, WISCONSIN
From 02-MAY-18 20:04:00 to 02-MAY-18 20:04:00 (CST-6)
Location: ZENDA
Magnitude: 1.75 
Crop damage: 0.00K
Reported by: Public

Hail in WALWORTH, WISCONSIN
From 02-MAY-18 20:04:00 to 02-MAY-18 20:04:00 (CST-6)
Location: PELL LAKE
Magnitude: 1.75 
Crop damage: 0.00K
Reported by: Trained Spotter

Hail in WALWORTH, WISCONSIN
From 02-MAY-18 20:10:00 to 02-MAY-18 20:10:00 (CST-6)
Location: PELL LAKE
Magnitude: 1.50 
Crop damage: 0.00K
Reported by: Public

Hail in WALWORTH, WISCONSIN
From 02-MAY-18 20:12:00 to 02-MAY-18 20:12:00 (CST-6)
Location: GENOA CITY
Magnitude: 1.25 
Crop damage: 0.00K
Reported by: Public

Hail in KENOSHA, WISCONSIN
From 02-MAY-18 20:15:00 to 02-MAY-18 20:15:00 (CST-6)
Location: TWIN LAKES
Magnitude: 2.90 
Crop damage: 0.00K
Reported by: Public

Pictures of hail provided between 2 and 2.9 inches in diameter.

Hail in WALWORTH, WISCONSIN
From 02-MAY-18 20:15:00 to 02-MAY-18 20:15:00 (CST-6)
Location: GENOA CITY
Magnitude: 1.75 
Crop damage: 0.00K
Reported by: Trained Spotter

Thunderstorm Wind in JEFFERSON, WISCONSIN
From 02-MAY-18 18:58:00 to 02-MAY-18 18:58:00 (CST-6)
Location: LAKE MILLS
Magnitude: 61.00 EG
Property damage: 20.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Multiple large trees down in and around Lake Mills. One tree fell on a car. A power pole was blown to a position on an angle. Power was out.

Thunderstorm Wind in ROCK, WISCONSIN
From 02-MAY-18 19:20:00 to 02-MAY-18 19:20:00 (CST-6)
Location: DOWNTOWN JANESVILLE
Magnitude: 50.00 EG
Property damage: 5.00K
Crop damage: 0.00K
Reported by: Public

Wind driven, ping pong size hail damaging the siding of a home.

Thunderstorm Wind in WAUKESHA, WISCONSIN
From 02-MAY-18 19:27:00 to 02-MAY-18 19:27:00 (CST-6)
Location: UTICA
Magnitude: 50.00 EG
Property damage: 2.00K
Crop damage: 0.00K
Reported by: Public

A giant Willow Tree was snapped and a large Evergreen Tree was uprooted.

Thunderstorm Wind in WALWORTH, WISCONSIN
From 02-MAY-18 19:58:00 to 02-MAY-18 19:58:00 (CST-6)
Location: WILLIAMS BAY
Magnitude: 52.00 EG
Property damage: 1.00K
Crop damage: 0.00K
Reported by: Trained Spotter

A 70 foot Pine Tree was snapped halfway up the tree.

Thunderstorm Wind in ROCK, WISCONSIN
From 02-MAY-18 19:20:00 to 02-MAY-18 19:20:00 (CST-6)
Location: JANESVILLE AIRPORT
Magnitude: 50.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: ASOS

Thunderstorm Wind in WASHINGTON, WISCONSIN
From 02-MAY-18 19:35:00 to 02-MAY-18 19:35:00 (CST-6)
Location: MAYFIELD
Magnitude: 52.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Thunderstorm Wind in WAUKESHA, WISCONSIN
From 02-MAY-18 19:44:00 to 02-MAY-18 19:44:00 (CST-6)
Location: DOWNTOWN WAUKESHA
Magnitude: 52.00 EG
Crop damage: 0.00K
Reported by: Trained Spotter

Wind driven, one inch hail observed.

Hail in IOWA, WISCONSIN
From 02-MAY-18 18:00:00 to 02-MAY-18 18:00:00 (CST-6)
Location: MINERAL PT
Magnitude: 1.00 
Crop damage: 0.00K
Reported by: Social Media

Picture provided.

Hail in ROCK, WISCONSIN
From 02-MAY-18 18:55:00 to 02-MAY-18 18:55:00 (CST-6)
Location: EVANSVILLE
Magnitude: 1.00 
Crop damage: 0.00K
Reported by: Public

Hail in WALWORTH, WISCONSIN
From 02-MAY-18 19:58:00 to 02-MAY-18 19:58:00 (CST-6)
Location: WILLIAMS BAY
Magnitude: 2.50 
Property damage: 1.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Wind driven ping pong size hail broke a window on the 90 foot dome of the Yerkes Observatory.

Hail in JEFFERSON, WISCONSIN
From 02-MAY-18 19:10:00 to 02-MAY-18 19:10:00 (CST-6)
Location: WATERTOWN
Magnitude: 0.75 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Hail in DODGE, WISCONSIN
From 02-MAY-18 19:18:00 to 02-MAY-18 19:18:00 (CST-6)
Location: ASHIPPUN
Magnitude: 1.00 
Crop damage: 0.00K
Reported by: Public

A picture was provided.

Hail in ROCK, WISCONSIN
From 02-MAY-18 19:22:00 to 02-MAY-18 19:22:00 (CST-6)
Location: JANESVILLE AIRPORT
Magnitude: 1.50 
Crop damage: 0.00K
Reported by: Public

Hail in WAUKESHA, WISCONSIN
From 02-MAY-18 19:24:00 to 02-MAY-18 19:34:00 (CST-6)
Location: OCONOMOWOC LAKE
Magnitude: 1.25 
Crop damage: 0.00K
Reported by: Public

Hail in WAUKESHA, WISCONSIN
From 02-MAY-18 19:26:00 to 02-MAY-18 19:26:00 (CST-6)
Location: BETHESDA
Magnitude: 1.00 
Crop damage: 0.00K
Reported by: Trained Spotter

Wind driven, large hail observed. Winds estimated around 55 mph.

Hail in WASHINGTON, WISCONSIN
From 02-MAY-18 19:43:00 to 02-MAY-18 19:43:00 (CST-6)
Location: GERMANTOWN
Magnitude: 0.75 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Hail in WALWORTH, WISCONSIN
From 02-MAY-18 19:46:00 to 02-MAY-18 19:46:00 (CST-6)
Location: DARIEN
Magnitude: 1.00 
Crop damage: 0.00K
Reported by: Public

Hail in WALWORTH, WISCONSIN
From 02-MAY-18 19:51:00 to 02-MAY-18 19:51:00 (CST-6)
Location: FONTANA
Magnitude: 1.00 
Crop damage: 0.00K
Reported by: Public