textproduct: Central Illinois

KEY MESSAGES

- A long-duration winter storm will impact the region in two waves spanning this afternoon through early Sunday evening. Snow amounts appear fairly light with the 1st wave, with 1 to 3 inches of snow by midnight tonight (highest south of I-70). however, more accumulating snow arrives later tonight into Sunday.

- A Winter Storm Warning is in effect from Cass to Vermilion Counties southward from noon until 9 pm Sunday, with 5-11 inches of snow expected. The highest snow totals are expected near/south of I-70, where there is 40-70% chance for a foot or more of snow per NBM. A Winter Weather Advisory is posted north of the Winter Storm Warning, 2-4 inches of total snow is expected. Marshall county was added to the winter weather advisory which goes from noon until 6 pm Sunday.

- A Cold Weather Advisory remains in effect across central and southeast IL through noon. Wind chill values will range from 10 to 20 degrees below zero with the coldest readings from I-74 north. Another Cold Weather Advisory may be needed overnight Sunday night into Monday morning (80-90% chance per LREF).

UPDATE

Issued at 830 AM CST Sat Jan 24 2026

Strong 1042-mb sfc high remains centered over WI/N IL, with dry northeasterly flow through the low levels of the ILX CWA. 12z RAOBs from across the region sampled this dry air, with KILX having low RH below 800mb (~6 kft). Much further SE, KSGF (Springfield, MO) was saturated all the way to the sfc. Regional radar imagery from 1430z/830am showed light returns across the region, but mPING reports and sfc obs suggest snow has mainly been confined to MO, although just in the last 5-10 mins we're starting to see mPING reports east of the IL River.

Had considered slowing the onset of PoPs this morning due to the dry low-level air, but with the steady northeastward advance of snow reports at the sfc opted not to make any changes. The key messages remain unchanged. For today, expect snow chances to increase/spread northeast into the afternoon, with snow rates expected to be less than 0.25"/hour during the daytime hours (per the HREF).

Erwin

DISCUSSION

Issued at 345 AM CST Sat Jan 24 2026

Continued the Cold Weather Advisory for our CWA through noon today. Wind chills currently are 9-14 below zero in southeast IL, and 15-25 below zero over central IL, with Bloomington having the coldest wind chill of 26 below zero. Wind chills should elevate to since digits below zero in southeast IL and 10-15 below in central IL by late morning. So the Cold Weather Advisory may be able to cancel early, but if NE winds hold up slightly higher than this would keep lower wind chills. Temperatures were in the single digits below zero north of I-70, and single digits above zero southeast of a Paris to Mattoon to Litchfield line. North to NNE winds 7-14 mph and few gusts 15-18 mph was giving the bitter cold wind chills. A strong 1042-1044 mb arctic high pressure over the upper MS river valley and ridging into central IL was giving us this bitter cold airmass. A frontal boundary was near or just south of the Gulf coast with 1010 mb low pressure in south Texas near the Rio Grande river with a weak elongated surface trof extending into the Ozarks in western AR and sw MO.

We continued winter storm warning from Cass to Vermilion counties southward from noon today through 9 pm Sunday. Winter weather advisory for rest of CWA north of here (excluding Knox and Stark counties) from noon today until 6 pm Sunday.

Strong Arctic high pressure to slowly weaken to around 1040 mb by sunset as it drifts eastward across the Great Lakes region. Meanwhile a surface trof to deepen from the lower MS river valley ne into the TN and eastern Ohio river valley into tonight. We will see a prolonged period of overrunning/isentropic lift into central and southeast IL this afternoon through Sunday bringing several inches of snow to central and southeast IL, with much lighter amounts nw CWA which will be on the nw fringe of this winter wx system. The 1st wave of light snow to spread ne into sw CWA by midday, and over rest of CWA during this afternoon and continue this evening, and CAMs have trended slower with its arrival. So the winter weather headlines have been pushed back from a 9 am to noon start time today. Between 1-3 inches of snow is expected by midnight, with the higher amounts in southeast IL and less than 1 inch over Knox and Stark counties. The 06Z HRRR model shows light snow ending nw of the IL river overnight and most of the snow from 2nd wave late tonight and Sunday to be east of the IL river per HRRR model. Very cold today with highs of 7-12F over central IL and mid teens in southeast IL from I-70 southeast.

2nd wave of light to moderate snow to lift ne over central and se parts of CWA late tonight and Sunday morning, and a 3rd wave lifting through areas east of the IL river during Sunday afternoon and diminishing from west to east late Sunday afternoon/early Sunday evening. The mixed pcpn should be se of Lawrence county and mainly southeast of the Ohio river for Sat night into Sunday. Models continue to show highest snowfall amounts in southeast IL where 8-10 inches and locally up to a foot or more possible se of I-70. Between 2-4 inches of snow over the IL river valley (1-2 inches over Knox and Stark counties) and 4-8 inches in heart of central IL with the higher amounts further south/se you go. Will see a sharp cutoff of snowfall amounts over nw CWA and kept Knox and Stark counties out of the winter wx advisory. Northerly winds increase by Sunday afternoon and Sunday night with gusts 20-25 mph and could cause some blowing/drifting of the fluffy snow.

Another surge of arctic air arrives behind the winter wx system Sunday night with lows Sunday night zero to 5 below and wind chills likely reaching 10-20 below zero during overnight Sunday night into Monday morning, when we will likely need another cold weather advisory over much of our area. A strong Canadian high pressure 1040 mb or stronger to move into Texas and ridge ne into IL by midday Monday. This returns mostly sunny skies but bitter cold temps with highs in the lower teens. Bitter cold Monday night with lows zero to 5 below in eastern IL where wind chills could reach near cold weather advisory criteria again. Lows in the singles digits above zero over the IL river valley. The expected snow cover may also make it colder especially if we have clearer skies at night.

Slight moderation in temps on Tue with sw breezes ahead of a cold front that moves through dry during Tue afternoon. Highs in the mid to upper 20s Tue which is still about 10 degrees colder than normal, and this will likely be our mildest day during next week. A strong 500 mb low digging southward over the Great Lakes on Wed afternoon into Wed night could bring chance of light snow to parts of central/eastern IL Wed afternoon/evening. The ECMWF is stronger with this system which brings higher snow chances to central IL by Wed afternoon while GFS and GEM are much lighter with QPF. Another Canadian high pressure settles into the area during Thu and should bring dry/cold wx rest of week. We will be colder again Wed-Friday with highs in the mid teens to near 20F and getting closer to cold weather advisory criteria Wed night and Thu night. Slighter moderation in temps next week with highs getting back into the 20s, which is still 10-15 degrees below normal.

The Climate Prediction Center (CPC) 8-14 Day Outlook for Jan 31-Feb 6th shows 35-50% chance of below normal temperatures over central and southeast IL, while near normal temps over nw IL. There is a 40-50% chance of below normal precipitation across IL during the 1st week of February.

07

AVIATION

(For the 12z TAFs through 12z Sunday Morning) Issued at 518 AM CST Sat Jan 24 2026

A winter storm will spread -SN across the central IL terminals from the southwest this afternoon, continuing through tonight. IFR visibility and MVFR ceilings look to be common for the duration of the event, which will continue past the end of this TAF period. Northeast winds will be persistent through the next 24 hours, initially near 10 kt today then increasing to 10-14 kt tonight.

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ILX WATCHES/WARNINGS/ADVISORIES

Cold Weather Advisory until noon CST today for ILZ027>031- 036>038-040>057-061>063-066>068-071>073.

Winter Weather Advisory from noon today to 6 PM CST Sunday for ILZ029>031-036>038-040-041.

Winter Storm Warning from noon today to 9 PM CST Sunday for ILZ042>057-061>063-066>068-071>073.