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.

UPDATE

Issued at 758 PM CST Wed Feb 25 2026

A narrow but intense band of frontogenesis centered near 700 mb, will slide southeast across the ILX CWA, bringing a period of snow mainly north of a Rushville to Robinson line, with light rain farther south. OOz ILX sounding showed a substantial dry layer below 700 mb, but strong warm/moist advection in that layer is already acting to saturate top-down, evidenced by light radar returns (mostly virga) in a west-east stripe through the central CWA. Recently had a report of light snow reaching the ground in Farmington (Fulton Co.). Upstream obs have shown visibilities below 1 mile at times in central IA within the f-gen band where lift is maximized. Latest radar and model trends suggest a narrow NW-SE corridor from Fulton to Edgar Co, and about 1 county on either side of this line, where there is the best potential for up to 1" of snow within a few hour period late this evening and overnight. Relatively warm pavement will lead to melting on roadways initially, but briefly higher snow rates and temps falling below freezing could lead to some accumulation and slick spots on roads. Will be issuing a Special Weather Statement and graphic to highlight these impacts, given the higher confidence in locations that will be affected.

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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 06z TAFs through 06z Thursday Night) Issued at 1032 PM CST Wed Feb 25 2026

Light snow with MVFR visibility will spread southeast, affecting KPIA-KBMI-KCMI over the next several hours. There is a low probability of IFR ceiling/visibility for a brief time, primarily at KPIA. Farther south at KSPI-KDEC, precip will likely start as RA or RASN and end as -SN. Higher probabilities for MVFR ceilings will occur at KSPI-KDEC starting around 10-12z and persist through midday. VFR then expected for all sites through Thursday evening. Winds to generally be under 10 kt through the forecast, veering from north tonight, southeast Thu morning, and southwest Thu afternoon.

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ILX WATCHES/WARNINGS/ADVISORIES

None.