textproduct: Central Illinois

KEY MESSAGES

- Cool and breezy conditions will persist through Thursday with periods of light rain or drizzle.

- Near freezing temperatures will impact the region Friday night and Saturday night.

DISCUSSION

Issued at 115 PM CST Wed Nov 4 2026

Upper analysis early this afternoon shows an expansive trough/closed low located over the Upper Mississippi Valley. At the surface, a ~1000 mb occluded low is centered over northern Wisconsin with its trailing cold front stretched from the northern Great Lakes Region into the Tennessee Valley and through the Gulf coast states. A little closer to home, low stratus remains trapped beneath a steep inversion with similar conditions expected through tonight. Forecast soundings show periods of upward omega overlapping the low-level moisture, which may support patchy areas of drizzle through the evening. Cloud cover and elevated west-southwest winds should hold overnight temperatures in the middle to upper 40s.

By Thursday, the aforementioned surface low will begin lifting into eastern Ontario/Quebec with mid-level troughing becoming centered over the Great Lakes Region. A potent shortwave trough will dive south from central Ontario and send the low's moisture plume back south into the area. This will result in another day of overcast skies and scattered light rain showers or drizzle. A strong cold front will move through the area Thursday night, bringing drier and much cooler weather for the end of the week as high pressure settles into the region. Daytime highs on Friday and Saturday will only peak in the upper 40s to middle 50s. Overnight lows both Friday and Saturday nights will dip down near freezing, resulting in widespread frost development. Even though the growing season has officially ended, any late season gardeners will want to take necessary precautions to protect any sensitive plants.

Long range model guidance continues to favor mid-level ridging building over the central US heading into next week as a closed low works across the Gulf states, keeping things mostly dry through the foreseeable future. Rising mid-level heights will steadily increase temperatures early next week, with the NBM projecting highs to top out in the low to middle 60s.

AVIATION /00Z TAFS THROUGH 00Z FRIDAY/

Issued at 1013 PM CST Wed Nov 4 2026

A large area of broken ceilings with bases near 3k feet will dominate the area tonight. Guidance shows highest probability for breaks in the MVFR ceilings near I-72 especially at KSPI into Thursday morning. An upper level wave moving in from the northwest will bring a renewed round of MVFR ceilings for late Thi morning through the evening. As the wave moves overhead, scattered -SHRA will likely develop during the afternoon to evening, and may be accompanied by IFR ceilings and MVFR visibility at times. Southwest winds will be persistent through Thu afternoon, near 10 kt tonight, then gusts increasing to around 20 kt for afternoon. A cold front will veer winds to the west and northwest through Thursday evening.

ILX WATCHES/WARNINGS/ADVISORIES

None.