January 7, 2008: Hail and a tornado in Dane and Walworth Counties

Very rare, mid-winter, severe storms affected parts of south-central and southeast Wisconsin on January 7th - in the form of two tornadoes and scattered, large, hailstones, and downburst winds. The last time a tornado occurred in January in Wisconsin was on the 24th in 1967 in Green and Rock Counties (25-mile track). On January 7th, a low pressure moved northeast through western Wisconsin, allowing a warm front to push through southern Wisconsin. Temperatures rose into the lower to mid 60s over southeast Wisconsin with surface dewpoints peaking in the mid to upper 50s, resulting in moderate amounts of instablity. Strong, veering winds from the surface to the jet stream level generated sufficient wind shear that supported rotating updrafts in scattered supercell thunderstorms over southeast Wisconsin. A supercell thunderstorm, that had spun up a tornado in northeastern Illinois previously, then crossed the state line into south-central Walworth County (southeast of the city of Walworth) where it intesified and eventually spun up a tornado near Pell Lake that traveled into western Kenosha County. Another supercell spun up a tornado over the northern reaches of the city of Kensoha. Other scattered thunderstorms on this day across south-central and southeast Wisconsin dumped large hail up to 3/4 inch in diameter.