Updated 4:15PM CST…
The National Storm Prediction Center has updated the severe weather outlook for this Monday evening and overnight. The Enhanced Risk (tan-shaded) area has been expanded to include most of Missouri as well as southeastern Iowa and a good portion of western Illinois. The Slight Risk (yellow-shaded) area has been expanded and includes the westernmost portion of the Chicago area. And the Marginal Risk area has expanded to include the remainder of the Chicago area into northwest Indiana.
The main threat for the Chicago area continues to be damaging winds this evening into the overnight night hours.
CHICAGO — A good portion of the Chicago area will be under a Marginal Risk of severe thunderstorms this Monday evening into the overnight hours. The National Storm Prediction Center has a portion of the Chicago area in a Marginal Risk (dark-green-shaded area on the severe weather outlook map above depicting a 5% chance of severe storms within 25 miles of a given location) for severe thunderstorms from late afternoon into the evening and overnight. Strong to severe storms will increase the main threat of damaging winds here as the storms move into our area from the west, building on the very strong gusty winds already in place due to the tightening pressure gradient around an intensifying low pressure system.
This afternoon into the early evening hours a Slight Risk (yellow-shaded area on the map depicting a 15% chance of severe storms within 25 miles of a given location) will extend from Minnesota south through Iowa and western Illinois into Missouri and Arkansas. A stronger Enhanced Risk (tan-shaded-area depicting a 30% chance of severe storms this afternoon and evening) will exist over southern-central Missouri and northern Arkansas.
A deepening center of low pressure will move north-northeast out of the Dakotas into the Manitoba province of Canada today and tonight. The associated cold front will sweep across the northern and central plains with a wide band of showers and thunderstorms developing along and ahead of the front. The timing of the front has it passing over the Mississippi River this evening and west to east through the Chicago area during the late evening/overnight hours. Thunderstorms should end with the passage of the cold front – moving east of our area during the early morning hours Tuesday.