textproduct: Central Illinois

KEY MESSAGES

- Dry and cool weather will prevail through the start of the new week.

- Storm chances return midweek with strong to severe storms possible Tuesday afternoon. A more significant threat for severe is expected on Wednesday.

DISCUSSION

Issued at 111 PM CDT Sun Jun 14 2026

Surface observations show a cold front stretched from the eastern Great Lakes Region southwestward toward the Middle Mississippi Valley. Scattered showers and storms are ongoing along and behind the front from central Indiana into southern Illinois, but have since exited the forecast area as of early this afternoon. Surface ridging approaching from the west will continue to push this activity further east, parting way to drier and cooler weather the remainder of today.

Surface high pressure will slide through the area on Monday, keeping things cooler to start the new week. Winds flip around to the south Monday night/Tuesday, allowing moisture to advect back northward ahead of an approaching cold front. An upper shortwave trough will swing through the Midwest states by midday Tuesday, pushing the cold front through parts of central Illinois and sparking the development of scattered storms. Although dewpoints in the upper 50s will limit instability, increasing mid-level flow will lead to sufficient shear for storm organization. Forecast soundings favor low-topped convection with short yet chubby CAPE and a low-level inverted-V profiles, suggesting the potential for damaging wind gusts and large hail in any stronger storms. The threat for tornadoes appears low due to unidirectional low- level shear.

The threat for significant severe weather appears likely on Wednesday as a shortwave trough tracks through the Great Lakes Region. The previously mentioned cold front will push just south of the area Tuesday night as a surface low rapidly deepens over the Northern Plains states. The front will subsequently get lifted back northward as a warm front as the surface low/cold front approach from the west. Dewpoints in the 60s will pool near and south of the warm front, allowing strong instability to build (2000+ J/kg) by afternoon. A robust ~70 kt mid-level jet will nose into the Middle Mississippi Valley later on Wednesday with the LLJ nearing 50 kts by Wednesday evening. Forecast hodographs show long cyclonically curved profiles, supportive of supercell thunderstorms capable of all hazards at the onset, as shown in the 14.12Z RRFS. Fast storm motions should favor activity congealing into a line rather quickly, with threats transitioning to straight line damaging winds and embedded tornadoes. Heavy rain/localized flooding is also a threat with 2+ inch PWATs and warm rain processes supporting high rainfall rates. There is a 30%/enhanced risk in place for much of the area on Wednesday, though placement of the highest threats will continue to be refined in the coming days as surface low/frontal boundary placements become clearer.

Cool and dry weather returns under surface ridging for late week. Temperatures steadily climb back to near normal by next weekend as mid-level heights rise in response to a building ridge over the south-central US. Precipitation chances look to increase by next weekend as a series of shortwaves slide through the Midwest states.

AVIATION /00Z TAFS THROUGH 00Z TUESDAY/

Issued at 614 PM CDT Sun Jun 14 2026

VFR conditions are expected over the upcoming 24 hours, with periods of high clouds and diurnal cumulus around 5000 ft AGL. Winds NW 8-15 kts with a few gusts to 20 kts until 01Z-03Z, then light and variable by 04Z. Winds W 7-11 kts after 16Z-18Z.

ILX WATCHES/WARNINGS/ADVISORIES

None.