Hailstorms

Thunderstorm & Hail Basics...

Tornadoes, strong straight-line winds, flash flood producing rains, and large damaging hail

the National Weather Service (NWS) issues "Severe Thunderstorm Warnings" for

hail stones 3/4 inch in diameter or larger, and/or
straight-line wind gusts of 58 mph or higher (measured or implied by tree/structural damage)

Roughly 20% of all severe weather "events" in Wisconsin are hail events in which hailstones are at least 3/4 inch in diameter. Damaging, straight-line wind events make up about 72% of all severe weather events, while tornadoes add up to about 8%
Serious hailstorms (with hail stones 1.5 inch or larger in diameter) are not common in Wisconsin... however, when they do strike the result is significant property damage. Rarely is a person injured or killed by large hail in Wisconsin.
The peak hail season is April through August, although hail has been reported with thunderstorms in every month of the year.
The southern half of Wisconsin tends to have the greatest number of hail events...with Dane and La Cross counties leading the way. However, any Wisconsin county can have a serious hailstorm!
Any given location in Wisconsin will usually experience about 3 days with hail per year.
One of Wisconsin's worst hailstorm outbreak occurred on March 29, 1998, Central and East Central Wisconsin experienced prolific hail-producing thunderstorms resulting in damage that topped 10 million dollars. There were many reports of hail 2 to 3 inches in diameter, and hail 4 inches in diameter was reported in St. John in Calumet County!
On October 29, 1996, a hailstorm persisted for 5 minutes over the city of Mukwonago in Waukesha County. Hail stones up to 2 inches in diameter damaged over 200 automobiles and other home structures. Monetary losses reached 1.2 million dollars!

Know which county you live in or the name of the county you're in. The NWS issues severe thunderstorm warnings on a county basis.
Monitor a NOAA Weather Radio signal to obtain the latest forecasts and warnings issued by the NWS. Make sure the radio receiver has a battery backup. NWS warnings are broadcast on commercial radio and TV stations, as well as cable TV channels.
Postpone outdoor activities if the thunderstorms are imminent.
To protect your motor vehicle or other property from hail damage, try to park it in a garage or car port, or a tent with a strong canvas. If this is not possible, cover the vehicle with old blankets or jackets.
Don't treat "Severe Thunderstorm Warnings" lightly!!!

...Produced by Warning Coordination Meteorologists from the NWS Offices servicing the state of Wisconsin

URL: http://www.crh.noaa.gov/mkx/flyers/flyerhail.php