textproduct: Central Illinois

KEY MESSAGES

- Rain chances will gradually settle southward into the evening. There is a greater than 80% chance of seeing a half inch of rain in areas south of I-70, though totals over an inch would not be out of the question.

- While there will be a brief warmup on Saturday (highs reaching 75-80 degrees), a more substantial warming trend will hold off until mid to late next week.

DISCUSSION

Issued at 143 PM CDT Fri May 8 2026

Latest water vapor imagery shows a series of shortwaves extending from western Ontario into Kansas. Showers have been tracking eastward across the forecast area the last few hours. With time, this area of rain will settle south through this evening, as the waves move across Wisconsin and Illinois. By midnight, the rain should be limited to areas south of I-70, but exiting before sunrise. HREF guidance has a >80% chance of at least a half inch of rain near/south of I-70 through tonight, though the LPMM suggests potential for over an inch just south of I-70.

The next wave is scheduled to drop into the area by early Saturday evening. The bulk of the precipitation with this feature should be post-frontal, though some of the high-res models are suggesting a few showers may sneak into the far northern CWA late afternoon. Ahead of the front, temperatures should be able to reach close to 80 degrees across west central Illinois, but with more troughing settling into the Great Lakes, high temperatures return to the 60s to start the new week.

As we go further into next week, the persistent upper ridge over the western U.S. will gradually edge its way eastward. As this occurs, additional shortwaves will drop southeast along the periphery, with additional rain chances Tuesday/Tuesday night and again toward Thursday night or early Friday. However, the international models are showing signs of developing a blocking pattern late week, with low pressure loitering off the mid- Atlantic states. A gradual warming trend is expected with the ridge, and the blocking pattern would result in warm weather from late next week and persisting into the following week.

AVIATION /18Z TAFS THROUGH 18Z SATURDAY/

Issued at 1233 PM CDT Fri May 8 2026

Scattered showers will push through the regional terminals, mainly between 18z-00z, with gradually less coverage with northward extent. Confidence/coverage in attendant thunderstorms remains too low to mention in the TAF at this time, though there is less than a 30% chance for an isolated thunderstorm at KSPI and KDEC between 00z-04z.

Otherwise, ceilings are anticipated to remain VFR through this TAF cycle, with OVC/BKN coverage to start, then becoming SCT/FEW overnight into Saturday morning.

Winds will maintain a westerly component through this TAF cycle, with sustained afternoon speeds around 10 kts and occasional gusts to 20 kts, then diminishing tonight.

ILX WATCHES/WARNINGS/ADVISORIES

None.