textproduct: Central Illinois

KEY MESSAGES

- A fast-moving disturbance will bring a period of light snow tonight to IL, spreading into central IL during this evening and diminishing from west to east during overnight. Snowfall will generally be 1 inch or less. However, HREF has a 40-70% chance that some locations north of I-70, and along and east of a Galesburg to Springfield line to reach 1 inch or more snowfall. - More snow showers are expected during Friday afternoon and evening with a dusting expected and a few spots seeing up to a half inch. Blustery west northwest winds gusting up to 30 mph will occur behind a cold front Friday afternoon and bring in much cold air Friday night. - Cold January weather will prevail Saturday through Tuesday night over central/se IL. Lows will dip into the single digits Saturday night through Mon night, with wind chills zero to 10 below, and as cold as 5 to 15 below overnight Sunday night into Mon morning.

UPDATE

Issued at 752 PM CST Thu Jan 15 2026

Narrow band snow associated with a focused zone of isentropic lift was pushing into western IL currently. As ascent has increased over the past couple hours, have seen visibilities drop below 1 mile at times over portions of eastern IA. 00z ILX sounding shows a fair amount of dry air below 700 mb, but forecast soundings show this will be overcome quickly. Profiles show a 1-2 hour period of more intense lift within the DGZ, co-located with an isothermal layer. This raises the potential for a quick burst of 1" snowfall in spots this evening as the band shifts east across central IL. Have updated PoPs and timing to reflect latest trends. In addition, a shortwave rotating through Friday morning looks to bring a period of light snow and have updated PoPs and QPF to show additional accumulations of a half inch or less.

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DISCUSSION

Issued at 225 PM CST Thu Jan 15 2026

Abundant sunshine prevailed across central and southeast IL so far today, compliments of 1021 mb high pressure over LA and ridging northward over IL. West to sw winds were much lighter today than yesterday with speeds 5-10 mph and few gusts to 15 mph. Despite the sunshine, temps were below freezing in the mid to upper 20s at 2 pm.

A weather system over the Northern Plains will move into the upper MS river valley by midnight and into the IL river valley by sunrise Friday. Warm air advection and isentropic lift ahead of this system will likely develop a band of light snow to spread eastward across central IL during this evening, and diminish during overnight (lasting about 4 hours). We are still forecasting between half and 1 inch of snow over much of CWA, with HREF having 40-70% chance of 1 inch or more snowfall north of I-70 and from Galesburg to Springfield east. Evening lows in the low to mid 20s, coldest in eastern IL, with slowly rising temps later this evening and overnight with as SSW winds pick up. These sw breezes briefly bring milder air back into the area with highs in the upper 30s/lower 40s on Friday.

A strong mid/upper level trof will dig into the Midwest and IL Friday afternoon into Saturday. The CAMs are showing more scattered snow showers developing Fri afternoon into Fri evening as an arctic cold front passes through Fri afternoon/eve. This could bring quick snow burst and gusty winds as temps fall behind the cold front. Have increased chances of light snow showers Fri afternoon and evening to account for this possibility of snow bursts. Flurries will be possible Saturday and Sat evening with the deep trof. Lows Fri night in the mid to upper teens in central IL and lower 20s in southeast IL. The strong trof to keep temps well below normal over central/se IL from Saturday through Tue night. Lows in the single digits Sat night through Monday night(lower teens in southeast IL Sat and Sunday night) and wind chills zero to 10 below and as cold as 5-15 below overnight Sunday night into mid Monday morning. That period may get close to cold weather advisory criteria overnight Sunday night into Mon morning. Nearby Canadian high pressure early next week to keep us dry and cold. Temperatures to modify Wed with temps getting closer to normal with highs in the 30s. Will need to watch a possible southern stream storm system next Thu that could bring chance of mixed pcpn to central/se IL, though a few model members like ECMWF keep this system south of IL.

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AVIATION

(For the 06z TAFs through 06z Friday Night) Issued at 941 PM CST Thu Jan 15 2026

Band of SN with localized IFR visibility will shift east of the terminals between 06-08z, then conditions will turn VFR area- wide. However another band of -SN is forecast to affect the area between about 11-16z, primarily with MVFR conditions. After that snow diminishes, MVFR ceilings should persist into afternoon before rising to VFR. Scattered SHSN will be around from mid afternoon to early evening but coverage too low to include beyond VCSH at this point. Southwest winds tonight will veer WSW by late morning gusting near 20 kt, then lose gustiness after sunset while veering west.

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ILX WATCHES/WARNINGS/ADVISORIES

None.