textproduct: Central Illinois

KEY MESSAGES

- A strong cold front will bring periods of gusty snow showers this evening, particularly in areas north of a Beardstown to Paris line. There, travel may become difficult as visibility falls sharply (one-half mile or less) over short distances and roadways become slippery within the heavier snow showers.

- Temperatures will oscillate between below normal and above normal through the middle of next week before stabilizing colder to end next week. The colder weather to close out next week may coincide (20-30% chance) with a flurry of light snow events.

DISCUSSION

(through next Saturday) Issued at 1216 PM CST Sat Jan 10 2026

A pair of mid-level disturbances continue to phase together over the Midwest this afternoon, with a band of light precipitation now shifting eastward toward Indiana associated with the leading shortwave and a low-level baroclinic zone. The p-type with this leading band has featured mostly rain, with the surface wet-bulb temperature convincingly above freezing. Occasionally, we have observed a quick change-over to snow wherever mesoscale forcing/cooling has become enhanced within the strongest FGEN (850-700mb). Even then, winter impacts have been limited or none at all.

The greater potential impact comes this evening as the trailing shortwave and associated cold front push across central Illinois. Recent hi-res guidance has been consistent in its depiction of gusty snow showers developing along and behind this cold front during the evening hours. The main questions that remain unresolved are which QPF is most likely and what the maximum wind gusts might be.

Regarding the QPF, the latest values from both the Mean HREF and Mean REFS generally lie in the range of 0.01"-0.05". Assuming a snow-to-liquid (SLR) ratio of 12:1, snowfall would most commonly range between a tenth and one-half inch. However, in a case like this where the synoptic and mesoscale forcings will become quite robust (MSLP rise/fall couplet; strong low- level FGEN; steeping lapse rates; an axis of SBCAPE; the intersection of upward omega and saturated DGZ; and the potential for CSI), it can be wise to lean toward the upper tail of QPF guidance. In such case, the Max HREF QPF and Max REFS QPF lie in the range of 0.1-0.4". Again assuming an SLR of 12:1, snowfall could range between 1-4 inches. It is an important disclaimer that not all areas should expect 1-4 inches of snow, but that in localized areas where all the forcing mechanisms might come aligned, this could become an advisory- level snowfall for a few of us. Best we can tell for now, the Interstate 74 corridor appears to be an area where the best forcing mechanisms could become aligned between 23z-08z (5pm-2am).

Any heavier snow showers that do develop this evening will be amplified by gusty winds. Recent mesoscale soundings depict low- level lapse rates that approach the DALR late tonight behind the cold front, with surface gusts in the 25-35 mph range. The combination of gusty winds and snow dendrites that lean on the chubbier side could make for difficult travel, as visibility becomes sharply reduced over short distances (one-quarter mile or less). Such is the hallmark of snow squall type events.

While some consideration for a winter weather advisory was considered on this shift, confidence and coverage of advisory- level snow remain too low at the current time. Instead, we have opted for a special weather statement highlighting the potential for impactful snow showers. Trends will be monitored and headline decisions will be dictated by what evolves upstream later this afternoon.

A raw January day is in store for Sunday as breezy north winds advect-in much colder temperatures. Wind chill values Sunday morning behind the departing frontal system will fall to near 10 degrees above zero. Daytime highs will then struggle to warm into the 30s.

Temperatures whipsaw warmer for Monday and Tuesday as deep northwest flow spills down the lee of the Rockies, prompting a period of compressional warming which will ultimately advect eastward into the Midwest. Afternoon highs on Monday are forecast to warm well into the 40s, with daytime highs on Tuesday surging into the 50s for most.

Intra-season volatility will persist through the middle of next week as atmospheric flow turns meridional with the polar jet stream buckling over the central US. The net effect will be periods of snow showers and much colder temperatures late Tuesday night into Wednesday as another strong cold front pushes across the Great Lakes. Exact mesoscale details are murky for now, but the ensemble mean across the three major forecast systems (GEFS, EPS, and GEPS) supports around one-half inch of new snowfall through Wednesday night.

The pattern for late next week looks like it will favor a continuation of choppy meridional flow, with additional bursts of light snow possible (20-30% chance). There is no signal for a winter storm, but a parade of shortwaves rotating through the region within north/northwest flow may gradually result in a blanket of new snow by the end of next week.

MJA

AVIATION

(For the 18z TAFs through 18z Sunday Afternoon) Issued at 1116 AM CST Sat Jan 10 2026

RASN has pushed east of the terminals, leaving IFR and MVFR ceilings across central IL. Short range guidance shows medium to high probabilities that these ceilings will scatter out at times this afternoon. Another disturbance will push in from the northwest this evening and bring another round of precip. Currently appears the I-74 corridor will be most in line for a few hours of SHSN and MVFR to IFR visibilities, though there is a low chance (30%) that KPIA-KBMI-KCMI will see LIFR visibility in heavier SHSN. For KSPI-KDEC where temperatures a slightly warmer, precip type is lower confidence and included -RASN. After this initial push of precip, isolated SHSN will likely linger through much of the overnight and covered this with VCSH due to low coverage. Northwest winds will be persistent through the forecast and frequently gust 20-25 kt.

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ILX WATCHES/WARNINGS/ADVISORIES

None.