textproduct: Central Illinois

KEY MESSAGES

- The primary concern remains dangerously cold temperatures, with lows in the single digits and sub-zero wind chills each morning from Sunday through Tuesday. The coldest wind chills are expected overnight Sunday night and Monday morning. The HREF has an 80-100% chance of wind chills of 15 below or colder from I-72 north. Wind chills of 10 below likely could get as far south as I-70 by daybreak Monday. - An active storm track will bring a series of quick-moving systems to the region over the next several days. While significant snow accumulations are not forecasted, these disturbances will produce periodic organized snow showers, which may lead to periods of reduced visibility and slick spots on untreated roadways.

UPDATE

Issued at 857 PM CST Sat Jan 17 2026

The snow activity across southeast Iowa largely diminished as it crossed the MS River into west-central IL, though light snow has been observed at times in locations mainly near and north of a roughly Macomb to El Paso line. We updated the short term PoPs to account for this waning activity over the next couple hours.

Another subtle change was updating the winds and hourly temperatures tomorrow night by blending to the 00z HRRR and Consshort, which advertise a sharp drop in apparent temperatures following the front with many locations experiencing sub -20 wind chills by early Monday morning. Even if this is overdone, we suspect a Cold Weather Advisory will (95% chance) be warranted for at least areas along and north of I-70, if not the entire county warning area (CWA). There is even some potential (20-30% chance, per HREF) for locations in our far northwest (Macomb to Lacon) to briefly touch Extreme Cold Warning Criteria (-25 or colder wind chills). Forecast soundings from various CAMs also suggest wind gusts may approach 40 mph at times, making it feel even colder than the true wind chill, which is calculated off of sustained winds (forecast to run 18-25 mph). We encourage folks to stay in if possible, dress in multiple layers if venturing outdoors, and to keep an emergency supply kit in their cars; check in on your neighbors too.

Bumgardner

DISCUSSION

Issued at 245 PM CST Sat Jan 17 2026

Isolated to scattered light snow showers have developed and spread into central and northern IL (nw of a Champaign to Taylorville line) by mid afternoon. PIA vsby got down to 2-3 miles at times with these snow showers since 18Z/noon. A weak surface trof was pushing se toward Danville and Shelbyville at mid afternoon while the main cold front was se of IL over southeast IN and nw parts of KY and TN.

Aloft a strong 524 decameter 500 mb low near the IL/IA/MO border will pivot across central IL this afternoon and lift into northern IN during early evening.Steep lapse rates with this strong mid/upper low is helping to produce the isolated to scattered light snow showers over central/northern IL and they should diminish from the west during early to mid evening as upper level low passes by and losing diurnal enhancement. Brisk WSW to WNW winds gusting 23-33 mph will gradually subside during tonight though still remain gusty much of this evening. Low clouds to decrease some overnight with pretty cold lows in the upper single digits north of I-72 and lower teens from I-72 south. Wind chills should lower to zero to 10 below zero north of I-70 during overnight into mid Sunday morning.

1010 mb low pressure over central and southern Saskatchewan to dive southeast into the upper MS river valley by 18Z/noon Sunday and will see another deepening mid/upper level trof into IL during Sunday afternoon. This to bring another chance of light snow showers and scattered flurries to central IL during Sunday afternoon into early Sunday evening and some spots getting a light dusting with areas from I-74 north possibly seeing up to a half to 1 inch of snow. Highs Sunday in the mid to upper 20s, coldest from I-74 northeast.

Another arctic cold front to sweep southeast through IL during Sunday evening and will bring even colder air into the region Sunday night and Monday. Lows Sunday night of zero to 5 above from I-72 north and around 10F in southeast IL from I-70 south. Strong NW winds behind the arctic front Sunday night to bring wind chills down to 10-20 below zero from I-70 north overnight Sunday night into Monday morning. We may likely need a cold weather advisory during this time frame from I-70 north. Highs Monday only in the low to mid teens in central IL and 15-20F in southeast IL. Chances of snow showers on Monday should be confined to the Great Lakes region so we kept a dry forecast. Brisk WNW winds continue on Monday keeping temps well below normal along with bitter cold wind chills only modifying to 5 below to 5 above during Monday afternoon. Very cold yet Monday night with lows in the single digits and wind chills zero to 10 below.

A 1035 mb Canadian high pressure settles into the TN and lower MS river valleys on Tue with return sw winds starting to modify temps. Highs Tue in the upper 20s and lower 30s. Breezier west to SW winds Wed warm temps up more into the mid to upper 30s, but range from lower 30s over Knox, Stark and Marshall counties to the lower 40s in southeast IL. Models show a wx system passing north of IL into the Great Lakes over Tue night and early Wed and may get close enough to produce chance of light snow especially northern CWA. It will send a cold front se through central/se IL on Wed with the front reaching near the Ohio river by sunset Wed. Models are trending drier now on Thu and Thu night with wx system over the northern plains and Great Lakes. Models diverge with handling winter wx system late next week into next weekend. GFS model is much wetter than Ecmwf and GEM models especially during next weekend. We have just slight chance of light rain on Friday, then chance of light snow Fri night and Saturday with mixed pcpn possible in southeast IL where overrunning could occur with low pressure trof south of IL. Highs Thu in the upper 20s/lower 30s moderate into the 30s Fri with southeast IL near 40F. Temps then drop during next weekend as more colder air arrives from Canada.

The Climate Prediction Center (CPC) 8-14 Day Outlook for Jan 24-30th has a 50-60% chance of below normal temperatures over central and southeast IL, with precipitation trending near normal. From Jan 1-16th, Springfield, Lincoln and Peoria have been about 8 degrees warmer than normal. So the next two weeks or 2nd half of the month looks colder than normal.

07

AVIATION

(For the 06z TAFs through 06z Sunday Night) Issued at 1045 PM CST Sat Jan 17 2026

Cloud cover and light snow showers continue to spread east across central IL late Saturday evening, likely (60-80% chance) reaching DEC and CMI over the next couple hours. HREF/GLAMP guidance suggest this wave of ceilings will depart towards sunrise, with VFR conditions until the next wave of potential (50-60% chance) light snow arrives mid-late afternoon. Winds will back to a south-southwesterly direction during the morning, then sharply veer to westerly and increase behind a cold front Sunday evening when gusts to 30 kt will be common.

Bumgardner

ILX WATCHES/WARNINGS/ADVISORIES