textproduct: Central Illinois

KEY MESSAGES

- The primary concern is dangerously cold temperatures, particularly by Monday morning when there is reasonably high confidence that wind chill values will fall between 10 and 20 degrees below zero.

- 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.

DISCUSSION

Issued at 303 AM CST Sun Jan 18 2026

High-latitude ridging over Alaska will help displace Arctic air southward into central Illinois through Tuesday.

The primary concern will be dangerously cold temperatures. Lows are forecast to drop into the single digits, with sub-zero wind chills forecasted each morning through Tuesday. Among them, Monday morning stands out as the most hazardous as a gusty, arctic front races across the Midwest. Steepening lapse rates amid strong cold advection will help support frequent 30-40 mph gusts. The combination of blustery north winds and very cold ambient temperatures should support wind chill values of 10 to 20 degrees below zero by Monday morning. A Cold Weather Advisory has been issued across the region to raise awareness of these dangerous conditions.

Temperatures are then anticipated to moderate by the middle of the week as the eastern Pacific ridge collapses, allowing milder Gulf air to surge northward up the lower- and mid-Mississippi Valley.

An active storm track will persist through the middle of the week, bringing a wavetrain of disturbances across the Upper Midwest. These quick-hitting, clipper-like systems may occasionally impact central Illinois directly; however, they are not expected to develop into significant mid-latitude cyclones, and therefore are not forecasted to produce heavy snowfall.

A compact shortwave trough moving through central Illinois this afternoon could trigger our next round of organized snow showers. While low-level dry air and large dewpoint depressions might limit snow accumulation, strong ascent ahead of the trough, positioned within a deep DGZ, suggests a potential for seeder-feeder enhancement. This mechanism could lead to a quick, burst of snow as the system passes. The combination of high snow ratios and blustery winds may result in more blowing snow than accumulation.

Two more weak disturbances will cross the region: one Monday evening and another on Wednesday. These are expected to be nuisances rather than impactful events. The potential for a more significant winter-weather event is currently not anticipated until next weekend.

MJA

AVIATION

(For the 12z TAFs through 12z Monday Morning) Issued at 458 AM CST Sun Jan 18 2026

An area of low stratus will continue shifting eastward out of Illinois this morning. Further upstream across Missouri and Iowa, an expansive area of VFR condtions lie, and these conditions will return to all central Illinois terminals prior to 15z.

Later this afternoon, there is a 30% chance for snow showers to develop along the I-74 terminals, primarily between 23z-03z. During this time, MVFR conditions may return. However, the better chance for MVFR conditions return beyond that time as low clouds flood in behind a cold front.

Surface winds will maintain a westerly component through early afternoon, becoming northwesterly and gusty this evening behind the cold front.

MJA

ILX WATCHES/WARNINGS/ADVISORIES

Cold Weather Advisory from 3 AM to noon CST Monday for ILZ027>031-036>038-040>057-061>063.