textproduct: Central Illinois

KEY MESSAGES

- Light snow and flurries this afternoon and evening, primarily north of I-74 with no accumulation expected.

- Minor snow accumulations of a dusting to half inch Wednesday afternoon and evening north of I-72, mainly on grassy and elevated surfaces as temperatures warm above freezing into early evening.

- Seasonable temperatures this week are favored to trend above normal late this weekend and early next week.

DISCUSSION

Issued at 120 PM CST Tue Dec 30 2025

Visible satellite imagery shows a deck of stratocumulus spreading southeast across central IL ahead of a mid level shortwave. While the bulk of the forcing with this wave passes to our northeast through this evening, it will clip roughly the northeast quarter of the CWA, providing enough lift to saturate top-down and generate light snow and flurries. At 19z flurries with 7 mile visibility were reported at Lacon, with 1 mile visibility in light snow farther north at LaSalle. As the area of light snow slides southeast, HREF shows only a 10% chance of measurable snow over northern Champaign/Vermilion counties and lower probabilities to the southwest. Southwest winds will veer west- northwest later this evening as a surface trough passes, gusting 20-25 mph at times.

Attention turns to a second, more potent shortwave Wednesday afternoon which tracks a bit further south. This system presents a more robust moisture profile, however, thermal profiles from the HREF indicate surface temperatures warming into the mid-30s during the peak of the event. This combined with low snow rates will result in high melt rates on pavement, restricting minor accumulations (less than a half inch) primarily to grassy and elevated surfaces, north of I-72. Skies clear on Thursday as high pressure builds in, though northwesterly flow keeps highs in the mid 20s to low 30s.

The upper pattern late this week features a persistent northwest flow regime as a broad longwave trough remains anchored over the eastern U.S. Through time the trough weakens and low- amplitude ridging builds across the Plains, resulting in rising heights locally Sunday into early next week. Medium-high confidence exists in a thermal moderation for the back half of the forecast period. Looking at the CPC 6-10 day outlook, the trend toward above- normal temperatures is favored to persist through the first week of January. A split-flow upper level jet across the U.S. and Canada indicates non-impactful weather should continue into the middle of next week.

25

AVIATION

(For the 18z TAFs through 18z Wednesday Afternoon) Issued at 1141 AM CST Tue Dec 30 2025

Ahead of a weak frontal boundary, mostly light snow showers are drifting southeast across eastern Iowa and northwest Illinois. These may graze PIA and BMI to briefly reduce visibilities this afternoon and evening, though the probability of a flight category drop seemed too low (10-20%) to add that to the TAFs at this time. Early Wednesday morning, the front will cross the area, bringing a wind shift to northwesterly and a medium-high (60-80%) chance of MVFR ceilings by 12z.

Bumgardner

ILX WATCHES/WARNINGS/ADVISORIES

None.