textproduct: Central Illinois

KEY MESSAGES

- Beneficial rain is forecast Thursday into Thursday night, though rain amounts will vary widely. In any given location, there is a roughly 20% chance for more than an inch of rainfall, which could help the ongoing drought.

- There is a level 1 of 5 (marginal) risk for severe weather with showers and storms Thursday evening and night. The main hazard would be gusty to locally damaging wind gusts.

- Mild conditions will continue through tomorrow night. Seasonably cool and breezy weather will return this weekend, with a 50-60% chance of high temperatures below freezing by Sunday.

DISCUSSION

Issued at 308 PM CST Wed Jan 7 2026

High volatility is expected across the Midwest for the rest of the week, featuring erratic shifts in temperature, periods of gusty winds, strong thunderstorms, and light accumulating snow.

The action kicks off tomorrow as a robust shortwave trough lifts into the Central Plains and pivots across the Mid-Mississippi Valley. As its attendant surface low deepens and expands across the region, gusty southerly winds will aid in bringing sfc temps near 60 degF and dewpoints well into the 50s. At the same time, as top-down saturation occurs beneath broad jetstreak coupling and diffluence aloft, widespread showers and occasional thunderstorms are anticipated from afternoon through late evening.

Heavy rainfall is anticipated due to a combination of factors: strong synoptic ascent, unusually high early-January precipitable water (PWATs), the presence of convective elements, and a deep warm cloud layer. In addition, the mean wind (850-300 mb) is expected to remain largely parallel to the cold front, raising the possibility of training convection. Despite fast storm motions, which could lead to wide variations in localized amounts, the signal for heavy rain exists. This variability is highlighted by the most recent REFS 24-hour LPMM QPF, which shows a widespread 0.25" to 0.50", with isolated streaks exceeding 1.25".

The risk of severe weather remains murky given the limited instability but top-shelf kinematics. Recent CAMs suggest a broken line of convection will track east across portions of our area after approximately 5 PM. A second line of showers and storms may follow along the actual cold front overnight. A LLJ of 50 kts at 925mb accompanying both incoming waves poses a risk for isolated severe wind gusts reaching the surface. Separate from any thunderstorm activity, sustained southerly gradient winds of 20-25 mph are anticipated in the late afternoon and evening, with gusts potentially reaching 35 mph.

The threat for tornadoes along and ahead of the cold front remains low given the poor line-normal component with respect to the line of forcing; however, any development of bowing segments in the storm line will need careful monitoring.

A cold front arrives Friday morning, bringing potential gusty west-southwest winds. NAMNest Bufkit analysis suggests sustained winds over 20 mph and gusts above 35 mph (matching EPS ensemble mean), with the strongest winds west of I-55. Wintry weather and much colder temperatures return by Saturday after a pair of disturbances phase together over the central US. Current ensemble and blended guidance support accumulating snow across the northern half of Illinois, but with stingy probabilities (10-30%) of greater than 1".

MJA

AVIATION

(For the 18z TAFs through 18z Thursday Afternoon) Issued at 1139 AM CST Wed Jan 7 2026

Flight conditions have rapidly improved this afternoon with the fog quickly eroding. VFR conditions will remain in place through at least 09z across the regional terminals. Some question remains as to whether additional fog or low stratus redevelops Thursday morning ahead of a lifting warm front. Right now, even our short- term, hi-resolution forecast guidance is offering mixed signals regarding the return of sub-VFR conditions by, or shortly after, 12z. With that fact in mind, we are supporting a medium probability (40-50%) of sub-VFR ceilings beyond 12z. In a similar manner, we are supporting a low probability (30%) probability for sub-VFR visibility.

Otherwise, surface winds will maintain its southerly component through this TAF period with sustained speeds increasing to 10-15 kts Thursday morning ahead of a cold front, and becoming gusty by the end of the period.

MJA

ILX WATCHES/WARNINGS/ADVISORIES

None.