Risk of severe thunderstorms with damaging winds and large hail and localized flooding area-wide Wednesday/Wednesday night

The National Storm Prediction Center has the Chicago area positioned in the center of a Slight Risk of Severe thunderstorms that includes all of Wisconsin, most of Illinois, northern Indiana, western Lower Michigan as well as eastern portions of Iowa and Missouri (see yellow-shaded area on the highlighted map depicting a 15% chance of severe storms within 25 miles of a given location).

A few thunderstorms could develop as soon as later this morning and early afternoon, but the highest threat appears to be mid-to-late afternoon into the evening hours. Greatest risk will involve damaging winds to 60 miles per hour and large hail – half-dollar sized or greater along with heavy flash-flood-producing downpours of 1 to 2-inches in a short period of time.

With very unstable air overhead, dew points in the upper 60s and lower 70s, and temperatures expected to warm into the 90s during peak-heating, minor impulses aloft are expected to easily trigger storm clusters that can develop quickly and produce severe weather/localized flooding.

Most of our area is also included in an Excessive Rainfall outlook (yellow-shaded area on the Excessive Rainfall outlook map below, so localized flooding will be a problem, especially should storms develop/occur in those areas where heavy rains/flooding occurred yesterday.

Excessive rainfall Outlook map…

Day 1 Excessive Rainfall Forecast