All week we've been advertising miserably hot, humid conditions for Thursday. The time for talk is about over. This afternoon is noticeably more humid than 24 hours ago with dewpoints in the 70s... or the "air you can wear" on the Muggy Meter.
Low-level moisture continues increasing the next 24 hours and the Muggy Meter will be about as bad as it gets around here on Thursday. The combination of temperatures in the 90s and dewpoints well in the 70s produces peak heat indices of 100°-105° before thunderstorms erupt in the highly humid air Thursday afternoon. You'll certainly want to take safety precautions if you're planning on being outside for extended periods of time.
In addition to the tropical heat, severe storms are possible... both in the morning and in the afternoon.
A severe storm complex will emerge in the Upper Midwest this evening on the eastern edge of the hot dome. This complex quickly intensifies, propagates to the southeast, and likely produce a swath of destructive wind from Wisconsin to southern Lower Michigan... and possibly into northern Indiana too. It's uncertain how far south this complex will travel and whether or not it holds together long enough to reach the Indy metro area before noon Thursday.
A more plausible scenario appears to be that any remnants would be more likely north-northeast of Indy where severe wind is possible along/north of a line from Monticello-Marion-Muncie.
Providing there isn't too much cloud debris from this feature, temperatures quickly soar into the 90s Thursday and heat indices peak 100-105°. A second wave of heavy storms develops in the afternoon within a zone of highly moist, unstable air. Damaging wind gusts and flash-flooding rain rates will be main threats with these storms between 2 PM - 9 PM Thursday.
The severe threat is quickly replaced by refreshing air Thursday night for a pleasant opening day at the Indiana State Fair on Friday.
