Chicago area under a risk of severe thunderstorms later Thursday/Thursday night
With warmer moist air flowing into the Chicago area Thursday and a cold front approaching from the northwest, there will be an increasing probability of shower and thunderstorm development that afternoon. The cold front will move southeast out of Wisconsin into northeast Illinois preceded and accompanied by strong to severe thunderstorms later in the afternoon into the evening and overnight hours.
The National Storm Prediction Center has placed the Chicago area in Slight to Marginal Risk of severe storms accompanied by damaging winds and hail later Thursday/Thursday night (see highlighted map). A Slight Risk (yellow-shaded are on the map calls for a 15% chance of severe storms within 25 miles of a given location and the Marginal Risk – dark-green-shaded area indicates a 5% chance. The greatest Enhanced Risk (tan-shade area depicting a 30% chance of severe storms within 25 miles of a given location) for severe storms is in Wisconsin during the afternoon/evening .
The cold front is not forecast to move east and south o our area until Friday morning, so the more storms hold off into the evening/overnight, we become further removed from the peak-heating most unstable part of the day, lowering the chances of severe storms.