textproduct: Central Illinois

KEY MESSAGES

- Temperatures will fluctuate significantly over the coming week. A swing to frigid conditions is expected late tonight, with much of the region seeing teens or even single digits. However, a much warmer bounce-back is forecast for the start of next week, with Monday and Tuesday anticipating highs in the 50s and 60s.

- The next opportunity for precipitation is forecast for Tuesday evening into Wednesday. Currently, there is a medium chance (40-60%) for this to begin as light rain before possibly transitioning to a wintry mix.

DISCUSSION

(through next Friday) Issued at 154 PM CST Fri Feb 6 2026

Following a breezy and mild day, temperatures are expected to drop sharply overnight. This change is associated with surface high pressure establishing itself over the Upper Mississippi Valley overnight with clearing skies, diminishing winds, and falling dew points likely returning to Illinois. Our forecast for overnight lows diverges from the NBM guidance, favoring the raw CAM output instead. We believe the CAM output, which shows lows in the lower teens to even single digits in typical cold areas, is more accurately capturing the effects of a strong radiational cooling pattern.

After a chilly start to the weekend, temperatures are expected to moderate by Sunday. This warming trend is due to a shortwave ridge axis moving east of the area, bringing in compressionally- warmed downslope flow from the Northern Plains. This process will intensify a low-level baroclinic zone, creating a significant west-to-east temperature gradient across Illinois Sunday afternoon. Specifically, areas in far west-central Illinois could see temperatures near 50 degF, while far eastern Illinois remains cooler, stuck in the mid-30s.

Despite the frontal zone pushing through central Illinois this weekend, no precipitation is anticipated. This is due to mid-level dry air in an otherwise poorly-forced, split- flow regime. This pattern will, however, result in some occasional low-level cloudiness on Sunday.

The more aggressive push of warm air is expected across the Midwest on Monday and Tuesday as low-level flow turns southerly ahead of two distinct shortwave troughs and their associated frontal zone. Forecast models, specifically NBM guidance, support widespread highs in the 50s on Monday, and temperatures potentially reaching around 60 degrees by Tuesday. These values seem reasonable as 850mb temps surge into the 10-12C range ahead of the approaching front.

The timing for the frontal passage remains between Tuesday evening and Wednesday afternoon, with light rain possible. The confidence for precipitation is medium (40-60%), but QPF Mean guidance is meager, suggesting only 0.1 to 0.3 inches. As the system exits on Wednesday, some of this precipitation may transition to light snow or freezing drizzle.

Approaching the latter half of next week, the forecast presents a complex range of competing solutions, including scenarios from cold and dry conditions to accumulating snow or even freezing rain. While confidence during this timeframe is currently low, it could prove to be the most impactful over the next 7 days, and is certainly worth monitoring.

MJA

AVIATION

(For the 18z TAFs through 18z Saturday Afternoon) Issued at 1126 AM CST Fri Feb 6 2026

MVFR ceilings will continue to push across the regional terminals through 00z in tandem with a weak cold front passing through. Low clouds will break and scatter near or prior to 06z, marking a return to VFR which will span into Saturday morning.

North winds will remain gusty through 06z before diminishing, becoming light and variable overnight as high pressure settles in.

MJA

ILX WATCHES/WARNINGS/ADVISORIES

None.