Showers/thunderstorms developing/spreading east and south ahead of approaching cold front

A line of showers and embedded thunderstorms is developing and spreading east and south across northern Illinois along and ahead of an approaching cold front this Tuesday afternoon. Locally heavy downpours and gusty winds could accompany some of the strongest storms (follow storm movement on the weather radar mosaic below).

Unseasonably mild moisture-laden air is riding southerly winds into our area ahead of the approaching cold front with temperatures in the 60s and lower 70s (73-degrees at Pontiac and 71-degrees at Kankakee at 3PM CDT) and dew points in the 50s to lower 60s.

The front will move fairly slowly through the Chicago area this evening and overnight with a extended period of locally heavy rains of an inch or more, especially south of Interstate-80. The National Weather Prediction Center has the portion of our area south of Interstate-80 in a Marginal Risk of Excessive rains/localized flood-producing downpours (dark-green-shaded area on the Excessive rainfall map below).

Excessive rainfall this afternoon/tonight…

Day 1 Excessive Rainfall Forecast

Regional Weather Radar Mosaic…