textproduct: Central Illinois

KEY MESSAGES

- Bitter cold continues this week, with low temperatures near or below zero and minimum wind chills falling 10 to 20 degrees below zero each night in most areas.

- Patchy blowing and drifting of snow is possible tonight into Tuesday morning.

DISCUSSION

Issued at 155 PM CST Mon Jan 26 2026

*** BITTER COLD CONTINUES THIS WEEK ***

Persistent bitter cold remains the top weather story for central and southeast Illinois over the next week. Early Mon afternoon, a 1040- mb sfc high was positioned over TX, with the sfc ridge axis extending NW towards the Ohio Valley. Further north, a sfc low was located over the Canadian Prairie. Winds across central IL are out of the west this afternoon, but will swing to southwesterly and become breezy tonight as the pressure gradient between these two sfc features tightens (sustained winds 15-20 mph, gusts as high as 30 mph). This could lead to patchy blowing and drifting snow tonight into Tuesday morning, especially in rural areas. Isolated travel impacts can't be ruled out, but the age of the snow pack (greater than 24 hours) does act to reduce the potential of blowing and drifting to some degree.

This morning, low temps verified closer to the HREF 25th percentile, as winds were lighter than forecast and skies mostly clear. Tonight/Tues AM will be a different story, though, with the breezy southwest flow acting to boost temps and lessen the effects of the snow pack (relative to a calm/clear night). Lows are forecast to be near/slightly above zero, with the coolest temps expected shortly after sundown and then a gradual warming trend overnight. Despite the warmer air temps, the breezier winds will push minimum wind chill values 10 to 15 degrees below zero along/east of I-55, where a Cold Weather Advisory is in effect. Given the non-diurnal temperature trend, the coldest wind chills will also be late this evening, with wind chills 'warming' to between 0 and 10 degrees below zero for the Tues AM bus stop. Tues night into Wed AM looks like a prime candidate for temps to verify colder than guidance, as a expansive sfc high shifts towards the central US, resulting in light winds and clear skies locally. Adjusted the temperature forecast below the NBM 25th percentile, resulting in low temps as cold as 8 below in some spots. With light, but not calm, winds forecast, this will once again result in wind chill values of 15 to 20 below Wed AM, and another Cold Weather Advisory (or perhaps Extreme Cold Warning) will be needed.

Additional cold weather advisories may be needed each night Wednesday through Friday, as low temps remain near zero and minimum wind chills approach 10 to 15 below.

*** PRECIP CHANCES (OR LACK THEREOF) ***

The 26.12z KILX sounding sampled just 0.06" PWAT, indicative of a very dry airmass in place in the wake of the winter storm. Ens guidance keeps PWAT values low through the period, commonly less than 0.20", which is about 20-40% of the average values for this time of year. With that in mind, it's going to be hard for precip chances to amount to much over the next week, but there are at least a few time frames to monitor for flurries/light snow.

The first is Tues as a sfc low/associated upper low track through the Upper Great Lakes. Model guidance has little to no QPF within the ILX CWA, but fcst sounding do show a saturated layer up to about 1500 feet AGL. Thankfully, this layer is entirely cooler than -10 degC, so if we were to squeeze any moisture out with this system it would be in the form of flurries, not freezing drizzle (a cloud layer warmer than -10 degC increases the potential of freezing drizzle). The best chance for any flurries would be north of I-74.

Another shortwave pivots into IL on Wed. Previous forecasts from the NBM had a slight chnc (15%) of measurable precip, but more recent forecasts have pushed the PoPs below 10%. LREF guidance has a 20-50% chance of at least a Trace of precip, so while measurable precip appears unlikely there is still a chance for flurries up to a dusting of snow on Wed. Fcst soundings saturate from the top-down, with a significant dry air present below 800mb which will make it difficult for precip to reach the sfc. Fcst soundings struggle to saturate this layer, but do eventually depict an hour or two where saturation descends all the way to the sfc. Left the NBM PoPs alone for now, but may need to increase the PoPs if the LREF signal holds.

Towards the latter part of the week, a sfc high over Canada will continue advecting dry low-level air towards central IL, such that despite another upper wave digging into the Midwest, guidance is skeptical that any precip occurs. PoPs are less than 10% on Fri.

While there won't be a late January thaw, there continues to be signs that the bitter cold relents as we head into February. It won't be a dramatic warmup or feature spring-like temps, but the ensemble probability of highs above freezing steadily increases each day next week, with a 40-60% chance during the latter half of next week (Feb 4-6).

Erwin

AVIATION

(For the 18z TAFs through 18z Tuesday Afternoon) Issued at 1059 AM CST Mon Jan 26 2026

VFR conditions through the period, with the TAFs primarily a wind forecast. Winds vary through the period, swinging from WNW to SW during the day, then gradually shifting back from SW to NW overnight into Tues AM. Maintained gusts through the overnight hours, but am somewhat uncertain as to whether or not they will continue. There are concerns about LLWS, between 03-09z, and due to a directional difference between the sfc and 2kft AGL, did include a LLWS group in the TAFs. If the sfc gusts diminish overnight, that will further increase the LLWS impacts.

Erwin

ILX WATCHES/WARNINGS/ADVISORIES

Cold Weather Advisory from 6 PM this evening to 6 AM CST Tuesday for ILZ038-042>044-051>054-061.

Cold Weather Advisory until 6 AM CST Tuesday for ILZ045-046- 055>057-062-063-066>068-071>073.