Late-Afternoon Analysis

Developing low pressure will move from Kansas into Iowa tomorrow providing the midwest with its highest threat of severe weather in months. Storms will be ongoing across Illinois as the sun rises Thursday. These storms are not expected to be severe. However as the low deepens the threat of severe will increase for areas of East-Central Illinois and Indiana. Our 13Microcast computer model plots the amount of instability or CAPE in the atmosphere. (Cape stands for Convective Available Potential Energy. It's directly related to the vertical speed that a thunderstorm is able to tap. The higher the CAPE, the higher the threat for severe weather). Notice how the highest CAPE is just to our east over Aurora and Joliet at 1pm. I do expect weather watches to be needed in Northern Illinois and Southern Wisconsin tomorrow, but it'll be very close. Certainly there's no reason to let your guard down, but it appears (as it looks right now) that the most significant hail, high winds, and tornado threat will be just to our east. This system is developing...there will be much more to talk about tonight and early tomorrow. Stay tuned! -ERIC