One-two punch of storms Tuesday morning and evening could be severe, cause flooding
A one-two punch of thunderstorms could generate spotty severe storms and localized flooding downpours across the Chicago area early and then again later Tuesday.
Spreading in from the west and associated with a warm frontal passage, the first cluster of storms should hit early Tuesday morning, reaching the immediate Chicago area around or a little after sunrise. A second round of storms preceding a cold front may be more widespread Tuesday afternoon/evening. Rain should end from the west later Tuesday night into early Wednesday.
The National Storm Prediction Center has outlooked the entire Chicago area in northeast Illinois and northwest Indiana in a Slight to Marginal Risk for severe thunderstorms Tuesday morning through Tuesday night – the Slight Risk looks to be primarily along and south of Interstate-80 (see yellow-shaded area on the headlined map depicting a 15 percent chance of severe storms within 25 miles of a given location). Damaging winds and large hail along with flood-producing downpours are the primary risks.
On the Excessive Rainfall map below, the Weather Prediction Center has outlooked the entire Chicago area in a Slight Risk of flood producing downpours of 1 to 3 inches during the same time-frame (see yellow-shaded area depicting a 10 to 20-percent chance of flooding within 25 miles of a given location).