textproduct: Central Illinois

KEY MESSAGES

- One more night of very cold conditions is expected tonight as lows fall to near zero and wind chills have potential to drop to around 10 below zero, then temperatures will slowly moderate the next few days. Temperatures should be only slightly below normal much of the upcoming work week.

- There is a 30-60% chance of light snow on Sunday north of I-70. Snow accumulations are unlikely to exceed one inch, but the light snow may still result in slick road surfaces.

- Another system could bring wintry precipitation to the region on Tuesday, mainly south of I-72 where there is a 30 percent chance of snow.

UPDATE

Issued at 727 PM CST Sat Jan 31 2026

Much of the light snow/flurry activity along the Indiana border has ended, though Evansville radar imagery continues to show a bit of activity along the Wabash River. Nighttime microphysics satellite continues to show a stream of cloudiness extending down from Lake Michigan into southeast Illinois, with some more scattered clouds as far west as I-55. HREF 925 mb humidity plots keep this plume of moisture most of the night, finally waning some closer to daybreak. With areas east of I-57 remaining mostly cloudy, that area should be kept somewhat warmer overnight, with lows around 5 degrees near the Indiana border. Elsewhere, mostly clear skies under the ridge axis should allow low temperatures near zero centered along I-55.

Geelhart

DISCUSSION

Issued at 239 PM CST Sat Jan 31 2026

Low level north-northeasterly flow at 925-700 mb continues to bring cloudiness and scattered flurries to east-central IL this afternoon, but satellite imagery depicts the band showing subtle signs of shifting eastward over Lake Michigan, which along with ridging building into the area from the west, should diminish this activity from west to east late this afternoon and evening, however will need to keep monitoring into the evening.

The aforementioned high pressure should bring mostly clear skies, at least for a portion of tonight, along with winds diminishing to light and variable. Resulting lows should approach zero, especially in the most-central parts of IL, but with light winds, wind chills won't be pronounced, likely near zero to as low as 10 below.

The upper level trough currently producing snow from the central into northern Plains will arrive during the day on Sunday. Models depict precipitation amounts becoming lighter as it arrives in central IL, however with a high likelihood of a hundredth or two of precipitation. Precipitation type is depicted as snow, however model soundings show depth of saturation struggling at times to be high enough to reach the dendritic growth zone. As a result, it wouldn't be impossible to see some freezing drizzle. Nevertheless, likelihood of reaching an inch are quite low, under 20 percent, and a minimal dusting to half inch is more likely. Snow looks to to arrive west of the IL River early in the afternoon, and reach the I-57 corridor by late afternoon. Snow should end overnight. South of I-70, have only incorporated a slight chance/20 percent.

Temperatures will moderate next week, with arctic air remaining to the north and more of a Pacific origin impacting central IL. Highs should reach the mid 20s Sunday, lower 30s Monday, then 20s and 30s much of next week.

The next precipitation feature for the region looks on track for Tuesday, however models continue to advertise a southern track which should keep chances minimal north of I-72, and precipitation type snow for any of central and southeast IL, as opposed to a mix of rain and snow in southern IL.

Friday could see the next system as models indicate a fairly strong clipper system moving through the Great Lakes. The current track keep the bulk of the impacts to the north, but have a slight chance into Central IL given the long-range uncertainty.

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AVIATION

(For the 06z TAFs through 06z Sunday Night) Issued at 1034 PM CST Sat Jan 31 2026

Still seeing a stream of MVFR level clouds coming off Lake Michigan, extending as far west as a KORD-KDEC line. Ensemble guidance suggests this will persist at KCMI through about 10-11z, whereas KDEC will be in and out for a few hours.

Focus later in the TAF period shifts to an incoming system, which will bring lowering ceilings/visibilities and some light snow late Sunday afternoon into evening. By 00z, probabilities of ceilings below 3000 feet are up to about 60-70% from KPIA-KSPI, and quickly increasing early evening further east.

Geelhart

ILX WATCHES/WARNINGS/ADVISORIES

None.