May 1, 2012: Hail across four counties

Clusters of severe thunderstorms...producing large hail up to 1.75 inches in diameter and wind gusts up to 70 mph (61 knots) moved across much of Southeast Wisconsin and a portion of South-Central Wisconsin during the afternoon hours of May 3rd. The thunderstorms developed in the warm sector ahead of low pressure over southeast Minnesota and behind a warm front that extended from the low across central Wisconsin. The unstable atmosphere, with mixed layer CAPE of 1500 to 2000 J/kg, and 0-6 km bulk shear around 40 knots was supportive of supercell thunderstorms. Wet conditions due to heavy rain associated with the thunderstorms led to a multi-vehicle accident on Interstate 94 near Lake Mills In Jefferson County, injuring (indirectly-related) two of the drivers.