textproduct: Central Illinois

KEY MESSAGES

- Dry and cool weather will prevail today. Temperatures through the week will generally remain around normal, with highs in the upper 70s to mid 80s.

- Storm chances return midweek with strong to severe storms possible Tuesday afternoon. A more significant threat for severe is expected on Wednesday. SPC has an enhanced risk (level 3 of 5) over the majority of the forecast area Wednesday.

DISCUSSION

Issued at 235 AM CDT Mon Jun 15 2026

A high pressure is over the central CONUS and will drift eastward throughout the day today. Temperatures through the week will generally remain around normal, with highs in the upper 70s to mid 80s. Winds will be light and westerly. With the two systems this week, wind direction will bounce between westerly and southerly for the next two days. Winds will be quite breezy Tuesday, sustained to 15-20 mph and gust of 25-30 mph.

A weak wave/frontal boundary will move through tomorrow, bringing showers and thunderstorms back into central IL. SPC has a marginal risk for severe weather for eastern IL, east of I-55. Forecast soundings indicate bulk wind shear of 30-40 knots and lower MUCAPE (~1000 J/kg or less). The hazards of concern are gusty (up to 60 mph) winds and near severe/severe hail. The storms Tuesday could be strong to marginally severe during the afternoon into the evening. Uncertainty exists on how strong the storms could become. The RRFS indicates a mostly dry passage of the front for most of central IL. The HRRR and NAMNest show showers and storms with the front, but different degrees of coverage. Timing is in the morning into mid afternoon.

Wednesday is a much better set up for severe weather and potential flooding over tomorrow's storms. SPC has an enhanced risk (level 3 of 5) over the majority of the forecast area. The cold front from Tuesday will lift back up north as a warm front, lifting better moisture (dewpoints in the 70s and PWATS >2 inches) into central and southeastern IL ahead of the next round of rain. The LLJ should be increasing to nearly 50 knots into the evening. Supercells are possible at the start of the event, but quickly evolving into a QLCS wind event with embedded tornadoes. Timing for this event looks to be in the afternoon into the late evening, as per the usual around here. Stay tuned for future forecasts as the details become more apparent into the new week.

WPC has maintained an excessive rainfall slight risk for Wednesday. PWATs look to be around 2.0-2.2 inches. The storms would likely have torrential rain within them. With many rivers/streams already at or near flood and saturated soils, flooding could be a concern through Wednesday. The one saving factor would be the fast storm motions.

AVIATION /12Z TAFS THROUGH 12Z TUESDAY/

Issued at 551 AM CDT Mon Jun 15 2026

VFR conditions are expected through the 12z TAF period. Light, variable winds will become southerly by tonight, remaining light.

ILX WATCHES/WARNINGS/ADVISORIES

None.