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.

- 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 221 AM CST Sat Jan 17 2026

A strongly negative East Pacific Oscillation (EPO) is expected to persist through the middle of next week before moderating. This pattern will maintain high-latitude ridging over Alaska, displacing Arctic air southward into the Great Lakes and eventually central Illinois this weekend and early next week.

The primary concern will be dangerously cold temperatures. Lows are forecast to drop into the single digits, resulting in sub-zero wind chills each morning from Sunday through Tuesday. Temperatures are then anticipated to return to more seasonable conditions toward the middle of next week.

An active storm track will coincide with this cold air, 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 over the next week.

The first disturbance is expected to cross the Mid-Mississippi Valley this afternoon. Despite shallow moisture depth, the exceptionally cold 850-mb temperatures (-17 to -19 C) suggest the moisture will briefly align with the Dendritic Growth Zone (DGZ), supporting a few organized snow showers. Due to high snow-to- liquid ratios (SLRs) and blustery winds, most of the snow is expected to blow around rather than accumulate.

A compact shortwave trough moving through central Illinois Sunday afternoon could trigger another 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, heavy burst of snow as the system passes. Once again, the combination of high snow ratios and gusty 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 weather event, involving a wintry mix or freezing rain, is currently not anticipated until next weekend. This change is projected to occur due to the collapse of the eastern Pacific ridge, which will allow milder air from the Gulf to move northward into the lower Ohio Valley.

MJA

AVIATION

(For the 12z TAFs through 12z Sunday Morning) Issued at 531 AM CST Sat Jan 17 2026

An area of lower ceilings will continue its slow push across the central Illinois terminals this morning. Sites may occasionally fall to MVFR within this area of lower clouds, but the trend is for VFR conditions to be the dominant flight category through about 18z. After that time, a more convincing push of MVFR/IFR conditions will overspread the regional terminals in accordance with a band of light snow. Low ceilings will then scatter out late tonight, with VFR conditions across the board by Sunday morning.

Surface winds through the period will remain westerly and blustery, with sustained speeds between 10-15 kts and occasional gusts between 20-25 kts.

MJA

ILX WATCHES/WARNINGS/ADVISORIES

None.