textproduct: Central Illinois

KEY MESSAGES

- A fast-moving weather system brings light rain or a rain/snow mix this evening.

- Northwest winds will increase tonight and early Thursday, leading to wind chills in the single digits and teens.

- A significant warmup arrives early next week, with high confidence in temperatures rising well above seasonal averages Mon-Tue.

DISCUSSION

Issued at 125 PM CST Wed Dec 31 2025

A weak clipper is currently moving through the Upper Midwest and will impact northern portions of central Illinois this evening. Latest HRRR and RAP runs indicate precipitation will begin as light rain late this afternoon, then end as rain or a rain/snow mix this evening, north of I-72. A strong cold front will push in from the north as precipitation ends, with plummeting temperatures as northwest winds increase. 12z HREF indicates a 50-90% chance of gusts exceeding 25 mph northeast of a Galesburg to Paris line overnight. Lows should fall to the teens and low 20s, pushing wind chills down into the single digits and teens for early Thursday. Winds to decrease Thursday morning with surface ridging building in from the northwest, however temps will remain cool with highs in the upper 20s to lower 30s.

A northwest to southeast oriented ridge axis remains in place Friday and Saturday, providing dry and cool conditions. For the start of the next week, deterministic models (ECMWF and GFS) are in good agreement regarding the breakdown of the cold pattern. An upper- level ridge amplifies over the central U.S. on Sunday, shifting the storm track to our north. High confidence exists for a warmup starting Monday as southwesterly flow develops. NBM data indicates high temperatures will climb into the upper 40s to mid 50s for Monday and Tuesday, which is approximately 15 degrees above the climatological norm. The ECMWF EFI highlights this temperature shift, and the CPC 6-10 day outlook reinforces the trend, showing a strong signal for above-normal temperatures across Illinois through the end of the first week of January. There is high confidence in dry conditions prevailing through Wednesday.

25

AVIATION

(For the 18z TAFs through 18z Thursday Afternoon) Issued at 1114 AM CST Wed Dec 31 2025

Breezy west winds and low stratus will precede a cold frontal passage, becoming north tonight and diminishing behind the front.

This round of TAFs is written such that ceilings are anticipated to remain MVFR along and ahead of the front, though there are reasonably high probabilities (50-80%) that ceilings could fall into the IFR category between 01z-06z.

Low clouds will then become scoured out by a drier, subsident airmass descending in from the north between 09z-12z.

MJA

ILX WATCHES/WARNINGS/ADVISORIES

None.