textproduct: Central Illinois

This forecast discussion was created in the public domain by the National Weather Service. It can be found in its original form here.

KEY MESSAGES

- Isolated storms today: Isolated afternoon thunderstorms (20% to 30% chance) may develop south of Interstate 72 today, ending quickly after sunset.

- Heavy rain and flash flood risk Thursday through Saturday: A stalled front brings a 60% to 70% chance of rain and storms to central and southern Illinois. Slow- moving storms could trigger localized flash flooding, with a 30% chance of rainfall exceeding 2 inches south of Interstate 72.

- Extreme heat or active storms next week: High uncertainty exists for mid-July. A shifting high-pressure system could bring either dangerous heat and humidity or periodic storm complexes.

Sunday through Wednesday

Once the stalled front finally dissipates or shunts south late in the weekend, long-range guidance exhibits excellent agreement regarding the rapid expansion of a high-amplitude subtropical ridge over the central United States. Medium-range ensembles (GEFS/EPS/GEPS) consistently project an anomalous upper-level high centering over the Central Plains during the July 13-16 timeframe.

Sensible weather across central Illinois during this extended period will depend heavily on the exact longitudinal positioning of this ridge core. A more western ridge orientation would place the local area under active, northwest flow aloft. This pattern would open the door for periodic, ridge-riding Mesoscale Convective Systems (MCSs) that would temper afternoon temperatures via persistent cloud cover and convective debris. Conversely, if the ridge core migrates further eastward directly into the Corn Belt, a spell of dangerous, excessive heat and humidity could rapidly develop by mid-July. Given the typical model variance at day 6 and day 7, trends will be monitored closely over the coming forecast cycles.

AVIATION /18Z TAFS THROUGH 18Z THURSDAY/

Issued at 1248 PM CDT Wed Jul 8 2026

VFR conditions are largely anticipated to continue at all TAF sites through 18z Thursday. Brief MVFR ceilings may occur early this afternoon. Otherwise, there is a low (~20%) probability of ceilings below 6 kft after 12z Thursday morning as decaying storms approach from the northwest. Low confidence in any fog development Thursday morning.

ILX WATCHES/WARNINGS/ADVISORIES

None.

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