textproduct: Central Illinois

KEY MESSAGES

- A Cold Weather Advisory remains in effect through noon for wind chill values of 10 to 20 degrees below zero. The threat of very cold weather will likely return Thursday night and Friday and continue through at least the middle of next week.

- Near daily chances (10-30%) for light snow showers and flurries exist throughout this week and upcoming weekend, but with little or no new accumulation

UPDATE

Issued at 1050 AM CST Mon Jan 19 2026

Will continue the cold air advisory through noon across central and southeast IL. Wind chills currently range from 10-20 below zero from Springfield to Mattoon to Paris north to zero to 5 below in southeast IL south of I-70. Brisk WNW winds 16-26 mph and gusts 26-36 mph combined with temps in the single digits over central IL and low to mid teens in southeast IL giving these bitter cold wind chills especially in central/northern IL. Wind chills should slowly modify next few hours and still could be a few spots with wind chills near 15 below between noon and 1 pm but feel more areas will modify above cold wx advisory criteria after noon.

A few updates done to the forecast today with more cloud cover over central and northern CWA. We have streaks/bands of stratocumulus clouds (bases 2-3k ft) from Macomb to Lincoln to Paris ne, while high clouds streaming eastward into areas from I-72 south at late morning. Also increased WNW winds a bit higher into midday. Strong 1035-1037 mb Canadian high pressure over southeast NE and northeast KS will settle over the Ozarks and into the mid MS river valley by sunset, and slowly diminish the brisk WNW winds to 10-15 mph and gusts 18-25 mph by sunset. Very cold today with highs in the low to mid teens central IL (coldest from I-74 ne) and upper teens to near 20F in southeast IL.

07

DISCUSSION

Issued at 325 AM CST Mon Jan 19 2026

Periods of cold to occasionally very cold temperatures remain the primary forecast concern for the Midwest over the next 7 to 10 days. The pattern will largely be driven by a significant alignment of atmospheric teleconnections: the Arctic Oscillation (AO), North Atlantic Oscillation (NAO), and East Pacific Oscillation (EPO) are all deeply negative.

Analysis of this morning's northern hemisphere 5-wave chart confirms this setup. A massive ridge of high pressure is currently stationed over the Gulf of Alaska, which is a hallmark of a deeply negative EPO. At the same time, an anomalous ridge is impinging upon the North Pole, characteristic of a deeply negative AO. This configuration promotes the equatorward displacement of the Polar Vortex. Consequently, lobes of arctic air are expected to periodically slide down the eastern Pacific ridge toward the Great Lakes through the remainder of the month. The net impact will be occasional periods of below-normal temperatures, with readings projected to be 10 to 20 degrees below seasonal averages. This means there will be a handful of days forthcoming where afternoon highs struggle to rise into the 20s while overnight lows fall near or below zero.

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 significant snowfall over the next week.

The trend in the Eastern Pacific Oscillation (EPO) is a key teleconnections to watch. While currently deeply negative, the index is projected to trend toward neutral by the end of the week. This shift promotes a slight weakening and repositioning of the Alaskan ridge.

The change will allow moisture to leak under the ridge, a development supported by most model guidance. Specifically, a closed upper low is expected to meander past the California coast by Friday, drawing both Pacific and Gulf moisture into the southern US.

This pattern is anticipated to lead to a substantial overrunning event this weekend. Warm, moist air will ride over a strong cold dome descending across the Midwest, creating a threat of sleet and freezing rain across the South, and accumulating snow across parts of the Ozarks and Tennessee Valley.

For central Illinois, however, recent forecast cycles have indicated a colder and drier trend for the weekend, with the most impactful wintry precipitation likely tracking just south of the area.

MJA

AVIATION

(For the 18z TAFs through 18z Tuesday Afternoon) Issued at 1138 AM CST Mon Jan 19 2026

Bands of low level cloud cover around 2000 ft AGL continue to stream across central IL, mainly near I-74 and northward. Model guidance points to this thinning gradually today, so thinking any chances for MVFR cigs will be mainly confined to 18Z-20Z. Another shortwave currently over the upper plains should move over the area this evening, likely bringing mid-level cloud cover, but a few recent model runs have some MVFR level clouds with this feature. Current obs indicate mainly VFR in ND, so have maintained a VFR forecast after current low clouds dissipate. Winds WNW 15-20 kts with gusts 25-30 kts this afternoon, decreasing to W 6-10 kts by 00Z, and continuing to shift SW and decrease slightly overnight.

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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.