textproduct: Central Illinois

KEY MESSAGES

- Windy conditions are expected Tuesday night and Wednesday, with some gusts over 40 mph. Travel difficulties will be most noted on west-east roadways Tuesday night, then on north-south roads on Wednesday.

- While much of the precipitation with this system will be rain, Wednesday will have the potential for a few snow squalls, which would rapidly decrease visibility for short periods of time.

- Light snow will accompany another clipper system late this week, with about a 30-40% chance of seeing over an inch of snow near and north of I-74.

- Another surge of Arctic air is incoming for the weekend, with widespread wind chills below zero and temperatures about 25-30 degrees below normal.

LONG TERM

(Thursday through Next Monday) Issued at 200 PM CST Mon Dec 8 2025

Latest ensemble guidance has been trending more toward Thursday night into early Friday morning with the next clipper system, with the European guidance on the stronger side. NBM guidance shows about a 30-40% chance of more than 1 inch of snow near and north of I-74, fairly close to last night's LREF guidance. Deterministic guidance is also rather bullish on another area of light snow streaking eastward across the area on Saturday, with a handful of ensembles supporting it, though run-to-run consistency isn't in place yet.

Big question in the extended range will be with the next Arctic surge. NBM guidance continues to advertise temperatures a good 25-30 degrees below normal for the weekend, with lows mainly in the single digits and highs in the teens to lower 20s over most areas. Earlier guidance had been more supportive of a widespread wind chill below -15F (local cold weather advisory criteria), though the latest NBM is more in the -5 to -10 range. If we do get a decent amount of snow from the Thursday system, the fresh snow cover would help get temperatures down low enough to compensate. Wind chills by Sunday night would ease up as high pressure settles into the area.

Geelhart

AVIATION

(For the 18z TAFs through 18z Tuesday Afternoon) Issued at 1108 AM CST Mon Dec 8 2025

Aviation concerns pick up after 00Z, as south winds increase to 10-15 knots with some gusts in the 20 knot vicinity. While any ceilings through much of the period will largely be VFR, a storm system passing to the north will push a low cloud deck southward late in the period. Latest HREF guidance indicates as high as an 80% chance of ceilings below 1000 feet at KPIA/KBMI by 15Z, though this seems a bit aggressive at this time, and NBM guidance is more tame at about 15%. Will not bring ceilings this low yet, but will lower them to about 3500 feet by the end of the forecast period.

Geelhart

ILX WATCHES/WARNINGS/ADVISORIES

None.