Marginal Risk of severe thunderstorms this Saturday morning south of Interstate-80 – Lakeshore flooding in NW Indiana later this afternoon and overnight

The National Storm Prediction Center has outlooked the portion of the Chicago area south of Interstate-80 for a Marginal Risk of severe thunderstorms today (green-shaded area on the highlighted map depicting a 5% chance of severe storms within 25 miles of a given location). Later this afternoon into the overnight hours the Chicago National Weather Service Forecast Office has a Lakeshore Flood Advisory in effect from noon today until 3AM Sunday morning along the Indiana Lake Michigan shoreline due to developing strong northerly winds gusting 30 to 40 miles per hour or higher could build 12 to 16-foot waves and cause beach erosion and flooding (light-green-shaded Indiana Lake and Porter Counties on map below).

As a deepening center of low pressure tracks just to the south and east of Chicago, strong to possibly severe thunderstorms will develop along and just north and south of the low pressure track, occurring primarily this morning into early afternoon across southern portions of the Chicago area. Heavy rains of over an inch and localized flooding could occur in this same area south of Interstate-80. The Ohio Valley well to our south will be in a Slight Risk of severe storms today (yellow-shaded area on highlighted map)

Cold air will sweep into our area on strong northerly winds behind the departing center of low pressure this afternoon and overnight. Rain will become mixed with and possibly change over to wet snow, especially in the city of Chicago/north and west before diminishing later this evening. Little snow accumulation is expected. North to northwest winds will intensify and lead to the lakeshore flooding and possibly some lake-effect snow showers in northwest Indiana later tonight into early Sunday.

Lakeshore Flood Advisory…

Map of Forecast Area