textproduct: Central Illinois

KEY MESSAGES

- A period of rain and snow will occur overnight. While impacts overall will be minor, there remains about a 40% chance of more than an inch of snow in a narrow band, currently favored between I-74 and I-72.

- Unseasonably mild weather will close the work week, with high temperatures near 70 degrees Friday in west central Illinois.

- A more potent storm system early next week brings a better chance of accumulating snow and/or ice Sunday and Sunday night.

DISCUSSION

Issued at 205 PM CST Wed Feb 25 2026

Tonight and Thursday: =====================

Main forecast challenge in this time frame remains with the timing of overnight precipitation, and whether any light freezing drizzle accompanies it.

Afternoon water vapor imagery shows a number of swirls in the northwest flow over our area, but the main feature of interest is a shortwave currently over western South Dakota. Synoptic models have this feature near the Mississippi River by midnight. There still remains a fair amount of spread among the high-res models even at this short range, with the HRRR still oscillating with impacts near I-74 vs. I-72. Morning HREF run is focusing on some frontogenesis near I-74 early in the evening shifting southeast, though the core of it may outrun the main precip area. If this can get aligned, then there still remains a concern for a narrow band of heavier snow (HREF probably of more than an inch is around 40% in a corridor from Macomb to Decatur). However, in general, accumulations of a few tenths or less are expected, as the higher moisture in the column is generally only focused on about a 4-6 hour window. A short period of freezing drizzle can't be ruled out as the precip ends and ice crystals are lost in the column, with HREF probabilities of 20-30% of a light glaze from about Macomb to Mattoon.

Anything that does accumulate will melt quickly on Thursday, with high temperatures a couple degrees either side of 50.

Friday and Saturday: ====================

Another taste of spring is expected Friday, with highs well into the 60s across the forecast area, nudging 70 degrees in west central Illinois. A cold front is progged to move slowly across the area Friday night, before getting hung up near the Ohio Valley. With the Gulf cut off from any moisture return, this will be a dry frontal passage. Depending on how fast the front manages to pass, areas south of I-70 may still get up to near 60 on Saturday. Behind the front, the colder air lags behind somewhat, so mid 40s to lower 50s will be more common.

Sunday through next Wednesday: ==============================

March is looking to come in like a lion, with a pair of wintry weather periods that are the main concern. Not a lot has changed from earlier thinking with the late weekend system, which spreads an area of overrunning precipitation northeast across much of Illinois into the lower Ohio Valley. High pressure is expected to be anchored over the Great Lakes, which would put us in an east- northeast flow. Such a setup would be climatologically favorable for freezing rain in our area. NBM guidance seems a bit low with the freezing rain potential, and is largely going with a rain/snow mix transitioning to all snow north of I-70. Due to computer issues that impacted the guidance initialization, no change was made to try and increase the icing risk, but this is something that will need to be watched closely. Overnight LREF guidance (which includes GFS and Canadian ensembles, but not the European ones) was on this track, which highlighted a greater than 25% chance of more than 0.05 inches of ice accumulation near and south of I-72/Danville through Monday. Snow-wise, areas north of that area had about a 30-40% chance of more than a few inches per the LREF (which does include the European ensembles for this element).

There is more uncertainty in the Tuesday-Wednesday segment of the forecast, in regards to the placement of the trailing frontal boundary from the early week system. The deterministic GFS and Canadian models have a split upper flow phasing together around Tuesday, digging an upper trough which suppresses the boundary further south. However, the European model has less phasing and builds a ridge ahead of an upper low moving out of the 4-corners region, with the boundary still near or just south of the Ohio River. With the Sunday/Sunday night system more of an imminent issue, little focus was made to any sort of adjustments to the initialization in this period.

Geelhart

AVIATION

(For the 18z TAFs through 18z Thursday Afternoon) Issued at 1109 AM CST Wed Feb 25 2026

Main aviation concern will be with ceilings/visibilities overnight, as a band of light rain and snow moves across central Illinois. KSPI and perhaps KDEC look to get the brunt of the lower clouds, with a 60-80% chance of ceilings below 2000 feet mainly focused on the 06-11z time frame, though KSPI may linger as late as 15z. Ensembles also put the area near KSPI around a 40% chance of IFR ceilings early Thursday morning, though this is more uncertain and will not add it into the new TAF just yet. Further north, while the KPIA-KCMI corridor will likely see a period of MVFR visibilities with the snow, it currently appears ceilings should remain VFR.

Geelhart

ILX WATCHES/WARNINGS/ADVISORIES

None.