There is a threat of strong to severe thunderstorms across northeast Illinois into northwest Indiana this Tuesday afternoon/evening. Mid-summer-like conditions will prevail as strengthening southwest winds gusting over 30 mph will direct warm moisture-laden unstable air into our area in advance of an approaching cold front that will sweep through from the northwest this afternoon/early evening.
The National Storm Prediction Center has this area under a Marginal to Slight Risk of severe storms with the greatest risk from just west and north of Chicago south and east later today (yellow-shaded Slight Risk area on the headlined map). The main severe risk will be damaging winds and large hail.
The chance of thunderstorms within 12 miles of a given location is depicted on the maps below from 7AM to 11AM this morning, 11AM to mid-afternoon/3PM and 3PM to early evening 7PM CDT. Note the red-shaded 70%-plus area for later afternoon/early evening overlays much of the Slight Risk of Severe storms shown on the headlined map.
Storms should move off to the east this evening with cooler less humid high pressure spreading over our area overnight and Wednesday.