textproduct: Central Illinois

KEY MESSAGES

- Shower and thunderstorm chances will diminish toward areas south of I-72 today as a cold front migrates southward, also bringing considerably cooler conditions to the area.

- Another round of strong to potentially severe thunderstorms may accompany a strong cold front late Thursday afternoon and evening. The most recent SPC outlook highlights locations near and south of the I-72 corridor.

- Much cooler weather will settle into the region Friday through the weekend potentially resulting in areas of frost both Saturday and Sunday mornings.

DISCUSSION

Issued at 258 AM CDT Wed Oct 14 2026

A cold front currently between the I-55 and I-57 corridors in central IL early this morning will continue to migrate southward today, likely passing I-70 by noon, but likely stalling out before I- 64 late today through tonight. Shower and thunderstorm activity will follow the frontal zone, for PoPs decreasing in northern portions of the forecast area today. A disturbance tracking along the front will bring another intense period of widespread storm activity to southeast IL during the morning hours today, then a general lull in activity will take place this afternoon through evening. With 30-40 kts of deep layer shear and several hundred J/kg SBCAPE forecast, storms south of I-70 through this afternoon could have the potential to produce severe wind gusts to 60 mph. SPC continues a Marginal Risk for severe thunderstorms in this area today. Precipitation amounts will be generally light except for southeast IL, where amounts around a half inch can be expected in general, although high resolution ensembles indicate potential for isolated 2 inch rainfall in thunderstorms. WPC continues a Marginal Risk for excessive rainfall from around I-70 southward.

On Thursday, a surface low will will develop along the stalled frontal boundary in the southern Plains early in the morning and move through central IL during the afternoon. This feature should be coincident with 40-50 kts of deep layer shear and 500-1000 J/kg MLCAPE by afternoon. This should be sufficient for isolated damaging wind gusts and a tornado or two, and SPC has areas near and south of I-72 delineated for a Marginal Risk. Rainfall looks to be generally a half to one inch, but with perhaps a narrow corridor or two of 2 inch rainfall accumulations. WPC continues a Marginal Risk for excessive rainfall for most of the area.

Once the low ejects northeast of the area Friday night, a strong cold front will sweep through the area, bringing much cooler air to the region and gusty northwest winds. Precipitation will also taper off, but a few light showers can't be ruled out Friday as a strong upper level shortwave rotates through the area. Following this shortwave, several dry days are on track Saturday through at least early next week.

Temperatures today will be down considerably from yesterday's record high temperatures, with around 67 in Galesburg to around 80 in Lawrenceville as the front migrates south of the area and cloudy and/or rainy conditions suppress temperature rises. Similar highs are expected Thursday, before plummeting temperatures arrive for Friday. Highs should be mainly between 55 and 60 both Friday and Saturday, with lows dipping into the upper 30s both Friday night and Saturday night. Models center high pressure to the west Friday night, suggesting that western areas will be more prone to light winds and resulting cold pockets/areas of frost, then the high migrates just to the east Saturday night, suggesting eastern areas will be more vulnerable. Temperatures will begin to rebound strongly starting Sunday as the high migrates east and southerly flow begins. Highs should approach 70 Sunday, and trend upward a few degrees per day through the first half of next work week.

AVIATION /12Z TAFS THROUGH 12Z THURSDAY/

Issued at 546 AM CDT Wed Oct 14 2026

A cold front lingers in the vicinity of I-72 this morning with a disturbance traversing the frontal zone likely to bring showers especially along the I-72 corridor terminals KSPI-KDEC-KCMI and southward until around 16Z, although isolated showers will be possible to the north as well. Brief MVFR cigs and vsbys are possible in these showers. Otherwise, VFR conditions are likely until increased low level cloud cover brings MVFR cigs by around 17Z-20Z, likely continuing through the remainder of the TAF period, although with some uncertain breaks possible overnight. Another disturbance is expected to bring increasing chances for showers late in the period, and PROB30 for -shra is included after 09Z-10Z. Winds light and variable then turning N-NE up to 10 kts by 15Z-18Z.

ILX WATCHES/WARNINGS/ADVISORIES

None.