textproduct: Central Illinois

KEY MESSAGES

- Widespread showers and thunderstorms will move across central Illinois this afternoon and evening. There is a marginal risk for severe weather this afternoon west of a Taylorville to Gibson City line, primarily for damaging winds, but there is a 2% tornado risk west of I-55.

- Off-and-on showers and thunderstorms will linger Thursday and Friday as a cold front stalls over the region, though organized severe weather is not expected.

- Hot and humid conditions return Sunday into Tuesday, pushing heat index values near 100 degrees. However, passing thunderstorm clusters may periodically disrupt the intense heat and lower the temperatures some.

DISCUSSION

Issued at 251 AM CDT Wed Aug 5 2026

An area of precipitation is in western IL so far this morning and is decaying as it is moving east. There will be multiple rounds of showers and thunderstorms today as a cold front slowly pushes into the state then stalls out later today. There is a marginal risk for severe weather this afternoon, primarily for damaging winds, but there is a 2% tornado risk west of I-55.

It looks like the prime time for severe weather will be this afternoon from 19z to 03z (2pm to 10pm). The environment is decently supportive of severe. MUCAPE values (and similarly SBCAPE values with a small cap) of 1500-2500 J/kg and bulk shear values of 30-40 knots. SRH values look to be around 200-300 mostly west of I-55 where the 2% tornado risk exists. Overnight, the severe threat should wane without daytime heating. CAMs are depicting everything dissipating in eastern IL around 03-04z providing widespread dry conditions for a few hours tonight. The most extreme version of widespread drying conditions in the CAMs is the RRFS. RRFS is showing everything drying out by 00z and staying widely dry through about 09-10z tonight. The next round of showers and thunderstorms moves into southwest CWA looks to enter by 08-10z tonight.

WPC has a slight risk ERO for today. The CAMs are showing some training today focused near/along the MO/IA border and extending east into the central part of IL. LPMM is showing pockets of 3-5 inches across central IL. We will need to monitor for a flash flooding threat.

The front is going to linger over the area into the weekend, keeping us in an active pattern. Each day, from Thursday to Monday, could see some non-zero risks for severe weather (especially north of I-70), with the machine learning models pointing that way as well. Saturday looks to be the driest day in the forecast. Check back with upcoming forecasts to see if any severe threats have increased for the end of the week.

Highs in the 80s and low in the 60s continue. Temperatures look to near or rise above 90 degrees for highs by Sunday into Tuesday, with increasing humidity. The LREF shows a 50-80% chance of apparent temperatures being greater than 95 degrees on Monday afternoon and 40-60% chance on Tuesday afternoon across the entire forecast area. The CPC has both the 6-10 and 8-14 day outlooks with above normal temperatures. This is said with the caveat: if we get widespread thunderstorm activity in the beginning part of the week, the heat indices may not be able to achieve 95-100+ degrees.

AVIATION /06Z TAFS THROUGH 06Z THURSDAY/

Issued at 1246 AM CDT Wed Aug 5 2026

Showers and potentially a few thunderstorms associated with a mesoscale convective vortex look to track through northern portions of the area early this morning, possibly impacting KPIA and KBMI, and have included PROB30 for TSRA and MVFR cigs/vsby with this feature. Otherwise, increasing mid level clouds will take place early in the period, followed by a cold front bringing a more widespread threat for thunderstorms in the afternoon and evening. Winds SE-SW 4-8 kts, becoming light and variable after 02Z-05Z.

ILX WATCHES/WARNINGS/ADVISORIES

None.