Sep 22, 2012
A strong thunderstorm developed over southern Waukesha early this morning due to an unusual strong upper level disturbance that rotated south across Wisconsin. The storm never became severe, but it had produced a large quantity of small hail. The thunderstorm began producing hail across Dane county near Madison and continued to travel east at 45 mph. Hail reports of over 0.50 inches was reported, with the hail swath extending east across Jefferson, Waukesha, and Milwaukee Counties.
It's not rare to have hail storms this time of the year, but what made this event interesting was the lack of thunderstorms in the forecast. The combination of a very strong disturbance and the amount of weak instability was just enough to sustain updrafts within the storm. The hail from the storm was able to survive to the ground thanks to surface temperatures in the upper 40's. The radar did show pink colors in the reflectivity indicating the presense of hail falling, which is what exactly occurred over my location. What was more interesting was the storm tops were no taller than 28,000 feet, but from the ground it had resembled a typical 50,000 foot thunderstorm with heavy rain, frequent cloud to ground lightning, gusty winds, and small hail.
Thankfully the hail was no larger than pea size and damage was minimal. My car was able to escape the 5 minute barrage of what sounded like someone throwing rocks against the window.
Make sure to browse the news section for additional U.S. and Wisconsin weather news information.