Tornado and Hail in Wisconsin, May 12, 2000

During the mid and late morning of May 12, a high precipitation supercell thunderstorm developed in west-central Wisconsin and tracked east across the state for over two and a half hours. The storm produced a prolific path of large hail, a brief tornado, and a significant wet microburst across central and east central Wisconsin. The storm was one of the most damaging thunderstorms in Wisconsin history, producing well over $100 million in damage.The thunderstorm developed north of a warm front, which was located across the Wisconsin/Illinois border. The setup was favorable for what is known as "elevated" convection; that is, the source of the instability was aloft, and not surface-based. Elevated convection often produces large hail, and the May 12 storm was no exception.As the storm moved into central Wisconsin, numerous reports of large hail were received from Waushara and Winnebago counties. Baseball size hail was observed with the storm in Waushara county, two miles east of Coloma and in Dakota. Hail damaged many of the roofs of the more than 1,000 homes in Omro (Winnebago co.) alone.As the storm intensified, it produced extensive damage across Calumet and Manitowoc counties as microburst winds developed. Wind-driven hail shredded west-facing sides of homes and businesses that were caught in the path of the storm.The worst damage in Calumet county was in and around Chilton, where 2 inch hail and hurricane-force wind gusts (estimated near 80 mph) knocked holes in siding and tore the walls and roofs from some buildings. Over 1000 homes were damaged in the city of Chilton. Two hundred more sustained damage in the township of Charlestown.A brief tornado occurred as the storm entered Manitowoc county, but did no damage. At about 1150 a.m. CDT, microburst winds near 100 mph and 2 inch hail combined to produce very serious damage in St. Nazianz. Most of the homes in a mobile home park in St. Nazianz were overturned or knocked off their foundation by the straight-line wind. Thirty people were injured in Manitowoc county, most in St. Nazianz. In Manitowoc county, over 100 homes were destroyed by the combination of wind and hail. Many more were damaged.