textproduct: Central Illinois

KEY MESSAGES

- Bitterly cold conditions will arrive Wednesday night through Thursday night...with potentially record-breaking low temperatures at or slightly below zero by Friday morning.

- A fast-moving system will bring another period of light snow to the region this weekend. The 12z NBM indicates a 20-30% chance of snowfall exceeding 1 inch along and north of a Macomb to Tuscola line.

LONG TERM

(Thursday through Next Tuesday) Issued at 252 PM CST Tue Dec 2 2025

Canadian high pressure will settle into the Midwest on Thursday, bringing decreasing winds and plenty of sunshine. However with the heart of the cold airmass overhead, high temperatures will struggle to rise through the teens over the snow cover. Radiational cooling Thursday night will lead to the coldest readings of the winter season thus far. The latest guidance suggests lows bottoming out in the single digits everywhere north of I-70...with a few spots dropping below zero north of I-72. If these projected numbers are realized, record lows for December 5 will be broken at Peoria, Lincoln, and Springfield.

The extreme cold will be short-lived however, as temperatures quickly moderate back into the upper 20s and lower 30s for the remainder of the forecast period. Will need to keep an eye on a pair of weak systems that will skirt through the region during that time. The first is slated for late Saturday into Sunday, while the second will be in the vicinity by late Monday/Tuesday. Models have not resolved either system very well at this point...with the 12z ECMWF showing the first wave pushing into central Illinois on Sunday...and the GFS taking the track further south across Missouri into southern Illinois. Given the high degree of track uncertainty, have only mentioned low chance PoPs (20-40%) Saturday night into Sunday. As an early projection, the 12z NBM shows a low probability (20-30% chance) of over 1 inch of snow along/north of a Macomb to Tuscola line. This will likely be changed as the track forecast becomes better defined over the next couple of days.

Barnes

AVIATION

(For the 06z TAFs through 06z Wednesday Night) Issued at 1042 PM CST Tue Dec 2 2025

Late this evening and overnight, MVFR/IFR stratus mainly between 007-011 persists along and east of I-55 but should slowly continue to erode overnight into Wednesday morning. SSW winds around 9-12 kt are expected overnight, then will slowly veer to the west then northwest during the afternoon as a slow moving cold front sags into the region. MVFR/IFR ceilings will return along and behind the cold front, and there is a chance (30%) for light precip with the front. There remains uncertainty on the precip type, but both snow and drizzle will be possible with surface temps hovering near the freezing mark much of the afternoon.

Deubelbeiss

ILX WATCHES/WARNINGS/ADVISORIES

None.