textproduct: Central Illinois

KEY MESSAGES

- Temperatures remain seasonably cold through Saturday. Friday night will be the coldest, with a 60-80% chance for wind chills lower than 10 degrees below zero.

- On Friday evening, lake effect snow showers may (30% chance) impact areas north of a roughly Macomb to Paris line. While accumulations would be light, sharp reductions in visibility may accompany the heaviest showers.

- There is a 30-40% chance for light accumulating snow on Sunday, with amounts generally staying under an inch. Locally slick roadways would be the main impact.

- A corridor of accumulating snow may impact a portion of central or southeast Illinois Tuesday into Wednesday, but confidence is low on precisely where. At this time, there is a 20-40% chance for more than one inch of accumulation area-wide.

DISCUSSION

Issued at 134 PM CST Thu Jan 29 2026

***** COLD WEATHER CONTINUES *****

Early Thursday afternoon, scattered mid to high clouds, light winds, and temperatures generally in the teens were observed across central and southeast IL, under the influence of expansive 1030-1032mb surface pressure across the southern Canadian Prairies, Northern Plains, and Midwest. There have been a couple mping reports of snow across portions of east-central MO where ceilings area a little lower (5-7kft), though surface dewpoint depressions suggest little, if any, of this activity will make it into our neck of the woods; we've included a mention of flurries in our southwestern counties through the evening to account for the low chance of a couple flakes. HREF generally suggests a 30-50% chance of mid-high cloud cover overnight, which would offset radiational losses, but given the light winds temps could sink like a rock if we get some clearing, especially given the snow cover. We'll monitor observation and model trends through the evening in case we need to make adjustments, but for now Friday morning's lows are forecast to generally run from 5 below to 3 above, with wind chills a couple degrees cooler.

***** SNOW FRIDAY AFTERNOON-EVENING? *****

A compact but potent shortwave trough will drop south into the region from the Upper Midwest/Great Lakes tomorrow afternoon, bringing a sharp drop in temperatures aloft with HREF mean 850mb temps dropping to around -20 degC. This will result in steep lapse rates off the surface and perhaps even some instability poking into the DGZ, so even with anemic low level moisture we will likely see some snow shower activity. Virtually all of the 12z CAMs bring a brief burst of snow (even if light) into our northern counties tomorrow evening, though there are differences among them in intensity of snow, along with precise timing and location. If there were going to be impacts, it would likely be from a sudden drop in visibility from briefly moderate snow accompanied by wind gusts to 25-30 mph. The short duration of snow in any given location suggests accumulations should be light; HREF probs for more than 0.56" snow (uses 10:1 SLR) generally keeps the chance for more than 1" of accumulation (assuming our 18:1 SLR is correct) at generally less than 10% area wide.

***** COLDER FRIDAY NIGHT INTO SATURDAY *****

Given the semi-tight pressure gradient across the area and 15-18kt PBL winds advertised on forecast soundings Friday night into Saturday, we felt NBM's 10-15 mph winds were a bit low and boosted them to 15-20 mph with gusts to 25 mph, which lowered wind chills into the -10 to -16 range area-wide. Taking REFS, HREF, and LREF apparent temperatures together, we think a Cold Weather Advisory is possibly (40-60% chance) going to be needed for this coldest night in the 7 day forecast.

***** SNOW POTENTIAL LATE SUNDAY, TUESDAY-WEDNESDAY *****

Temperatures will gradually moderate next week, with highs making a run at the freezing mark each day Monday through Wednesday. However, we'll need to keep an eye on a couple disturbances slated to take aim at the district: the first late Sunday, and another Tuesday into Wednesday. Generally, ensemble guidance suggests low chances for substantial accumulations with the clipper system on Sunday, with only a 5-15% chance for more than an inch from NBM. The second system, however, will bear a little more watching, as a brief period of deep southwesterly return flow ahead of the upper level wave offers our area with a little Gulf Moisture. Temperatures aloft may warm sufficiently that the initial p-type is rain or freezing rain, but then as conditions cool again on the low's northwest side a portion of our area may receive some accumulating snow with various iterations of deterministic models advertising a band of 3+ inches, though discrepancies in specifically where. For what it's worth, NBM chances for more than an inch generally range from 25-40% in our area, highest near and north of the I-74 corridor.

Bumgardner

AVIATION

(For the 00z TAFs through 00z Friday Evening) Issued at 508 PM CST Thu Jan 29 2026

In general, VFR conditions will prevail through the period. Mainly mid and high level clouds are expected into Friday morning. However, a general lowering of ceilings will take place in the afternoon, as an upper disturbance swings into the area. HREF and NBM guidance suggests probabilities of MVFR ceilings increasing to 40-60% late afternoon. Any ceilings below 3,000 feet look like they would be of a shorter duration, mainly less than 6 hours, and would extend for a couple hours beyond the current forecast period.

Geelhart

ILX WATCHES/WARNINGS/ADVISORIES

None.