Scattered thunderstorms continue to move across north-central Illinois Tuesday evening, producing mostly heavy rainfall and frequent lightning. There is just enough spin present in the atmosphere to allow some of the storms to show some signs of very weak rotation as they continue to lift northeast. This is evident by looking at some of the lowering of the storm bases with these storms. However, there just isn’t enough in the atmosphere to really allow the storms to maintain themselves.
So the greatest risk will remain pea sized hail and wind gusts 40-50mph.
Scattered thunderstorms have quickly developed Tuesday evening over much of northern Illinois ahead of a cold front and surface low pressure system moving into southwest Wisconsin. The risk for strong to severe storms is still present, but a little more on the lower end following some of the earlier storm activity Tuesday afternoon.
The storms moving through now will have very heavy rain and possibly small hail. There will be a wind risk, as well, with some of the stronger storms. Thunderstorm activity will continue through 8pm once the cold front comes through. After that, scattered showers will continue through Wednesday morning.