A second round of severe weather struck south-central and southeast Wisconsin overnight from the 11th into 12th.  Some of the thunderstorms developed supercell characteristic resulting in large damaging hail, downburst straight-line winds, and torrential rainfalls.  Nearly all of the severe storms in this round of activity leveled large trees and power lines. The worst damage was reported in the Allentown to West Bend area of Washington County, with two pole sheds and two residential garages sustaining considerable damage. Large hail up to golf ball size also occurred with the hurricane-force winds in Washington County.  Milwaukee and Waukesha counties also  experienced the same type of damage due to hurricane-force thunderstorm winds.  Two Brookfield (Waukesha Co.) homes were damaged when large trees were pushed on them.  In Cudahy (Milwaukee Co.), where a trained spotter's wind anemometer was blown away at 70 mph...the still-increasing winds pushed his home slightly off its foundation.Torrential rains coming down at the rate of 1 to 2 inches per hour in the more intense storms resulted in urban flooding as well. Many reports indicated that water was briefly 6 inches to almost 2 feet deep on some low-lying roads or underpasses. A peak rain of 3.6 inches in one hour was reported near the city of Racine!  Due to the toppled power lines, about 25,000 customers were without power at one time or another. Synoptically, a warm front, that was over northern Illinois on the 11th, moved into southern Wisconsin during the overnight hours.  This front served as a focus for the thunderstorm activity.

Hail in IOWA, WISCONSIN
From 11-MAY-00 21:14:00 to 11-MAY-00 21:14:00 (CST)
Location: ARENA
Magnitude: 1.00 
Reported by: TRAINED SPOTTER

Hail in DODGE, WISCONSIN
From 11-MAY-00 22:13:00 to 11-MAY-00 22:15:00 (CST)
Location: REESEVILLE
Magnitude: 0.75 
Reported by: AMATEUR RADIO

Thunderstorm Wind in JEFFERSON, WISCONSIN
From 11-MAY-00 22:46:00 to 11-MAY-00 22:46:00 (CST)
Location: WATERTOWN
Magnitude: 56 E
Property damage: 1K
Reported by: TRAINED SPOTTER

Flood in RACINE, WISCONSIN
From 12-MAY-00 00:15:00 to 12-MAY-00 01:30:00 (CST)
Location: STURTEVANT
Reported by: AMATEUR RADIO

Thunderstorm Wind in WAUKESHA, WISCONSIN
From 11-MAY-00 23:28:00 to 11-MAY-00 23:45:00 (CST)
Location: HARTLAND
Magnitude: 65 E
Property damage: 100K
Reported by: AMATEUR RADIO

Flood in WAUKESHA, WISCONSIN
From 11-MAY-00 23:30:00 to 12-MAY-00 01:00:00 (CST)
Location: COUNTYWIDE
Reported by: LAW ENFORCEMENT

Thunderstorm Wind in DANE, WISCONSIN
From 11-MAY-00 22:43:00 to 11-MAY-00 22:51:00 (CST)
Location: MARSHALL
Magnitude: 52 M
Property damage: 2K
Reported by: AMATEUR RADIO

Thunderstorm Wind in JEFFERSON, WISCONSIN
From 11-MAY-00 22:20:00 to 11-MAY-00 22:20:00 (CST)
Location: WATERTOWN
Magnitude: 52 E
Property damage: 1K
Reported by: TRAINED SPOTTER

Thunderstorm Wind in WASHINGTON, WISCONSIN
From 11-MAY-00 22:25:00 to 11-MAY-00 22:40:00 (CST)
Location: ALLENTON
Magnitude: 65 E
Property damage: 100K
Reported by: LAW ENFORCEMENT

Thunderstorm Wind in WAUKESHA, WISCONSIN
From 11-MAY-00 23:10:00 to 11-MAY-00 23:10:00 (CST)
Location: DELAFIELD
Magnitude: 52 E
Property damage: 1K
Reported by: LAW ENFORCEMENT

Hail in JEFFERSON, WISCONSIN
From 11-MAY-00 23:25:00 to 11-MAY-00 23:25:00 (CST)
Location: SULLIVAN
Magnitude: 0.75 
Reported by: OFFICIAL NWS OBS.

Thunderstorm Wind in MILWAUKEE, WISCONSIN
From 11-MAY-00 23:43:00 to 12-MAY-00 00:05:00 (CST)
Location: MILWAUKEE
Magnitude: 65 E
Property damage: 50K
Reported by: LAW ENFORCEMENT

Flood in MILWAUKEE, WISCONSIN
From 12-MAY-00 00:00:00 to 12-MAY-00 01:00:00 (CST)
Location: FRANKLIN
Reported by: LAW ENFORCEMENT

Hail in RACINE, WISCONSIN
From 12-MAY-00 00:09:00 to 12-MAY-00 00:12:00 (CST)
Location: UNION GROVE
Magnitude: 1.75 
Property damage: 5K
Reported by: AMATEUR RADIO

Thunderstorm Wind in DANE, WISCONSIN
From 11-MAY-00 23:30:00 to 11-MAY-00 23:35:00 (CST)
Location: MADISON
Property damage: 2K
Reported by: LAW ENFORCEMENT

Hail in JEFFERSON, WISCONSIN
From 11-MAY-00 22:28:00 to 11-MAY-00 22:28:00 (CST)
Location: SULLIVAN
Magnitude: 0.75 
Reported by: OFFICIAL NWS OBS.

Flood in DANE, WISCONSIN
From 11-MAY-00 22:30:00 to 11-MAY-00 23:30:00 (CST)
Location: MADISON
Reported by: LAW ENFORCEMENT

Thunderstorm Wind in MILWAUKEE, WISCONSIN
From 11-MAY-00 22:40:00 to 11-MAY-00 22:40:00 (CST)
Location: MILWAUKEE
Property damage: 1K
Reported by: LAW ENFORCEMENT