textproduct: Central Illinois

KEY MESSAGES

- Strong northwesterly winds gusting 40-50mph will accompany scattered rain and snow showers Wednesday morning.

- A clipper system will bring a round of light snow by Thursday night into Friday morning...with the 00z LREF suggesting a 40-60% chance of greater than 1 inch of snow along and north of a Macomb to Robinson line.

- Another surge of very cold air is expected by the end of the week...resulting in sub-zero apparent temperatures Friday night through Monday morning.

LONG TERM

(Thursday through Monday) Issued at 332 AM CST Tue Dec 9 2025

Models continue to struggle with the next in a series of clipper systems slated to impact parts of the region late this week into the weekend. The 00z Dec 9 suite is beginning to hone in on the Thursday night into Friday morning time frame: however, the exact track is still in question. Have therefore kept PoPs quite low (20%) during the day Thursday, but have increased them into the 30-50% range for Thursday night. While the system will not have a lot of moisture to work with, a light accumulation of snow is likely. The 00z LREF shows a 40-60% chance of greater than 1 inch along/northeast of a Macomb...to Springfield...to Robinson line...with just a 10% chance of over 3 inches along/north of I-74.

A second clipper will come into the picture by Saturday...with most guidance suggesting the highest probability of accumulating snow across Iowa into northern Illinois. Once this system exits, a bitterly cold airmass will settle into the Midwest through early next week. High temperatures will drop from the 30s on Friday into the teens for Saturday and Sunday. While wind-chill values will drop below zero across parts of the area by late Friday night, the coldest period will be Saturday night into Sunday when apparent temperatures will approach or exceed the -15F advisory criteria along/north of I-72. The extreme cold will begin to ease by Monday as boundary layer flow becomes S/SW and afternoon temperatures rise back well into the 20s and perhaps lower 30s in some spots.

Barnes

AVIATION

(For the 12z TAFs through 12z Wednesday Morning) Issued at 547 AM CST Tue Dec 9 2025

Mostly clear skies will prevail this morning, followed by increasing mid-level clouds at 8000-10000ft from north to south across the area this afternoon. Scattered showers will push through central Illinois tonight as low pressure tracks across Wisconsin into the Great Lakes. Based on latest HRRR/RAP, have introduced predominant showers at KPIA between 02z and 07z and further east to KCMI from 06z to 09z. Further south, have only mentioned VCSH at KSPI/KDEC. Winds will initially be SW with gusts of 20-25kt through the afternoon, then will increase during the evening as a cold front approaches from the northwest. Have ramped up gusts to around 30kt accordingly. VFR conditions are expected for much of the 12z TAF period: however, MVFR ceilings are progged to spill into KPIA/KBMI after 08z/09z.

Barnes

ILX WATCHES/WARNINGS/ADVISORIES

None.