textproduct: Central Illinois

KEY MESSAGES

- Localized Severe and Flooding Risk Today: A strong storm or two with primarily damaging wind gusts cannot be ruled out, mainly W of a Champaign to Taylorville line. Widespread showers and tstorms tonight may result in localized flooding in the SW.

- Occasional Showers & Storms Through Friday: A slow-moving cold front will support on-and-off rain chances (20-50% from the NBM) Thursday and Friday, especially into eastern Illinois.

- Heat/Humidity and MCS Chances Late Weekend: Favorable pattern for increased heat/humidity (heat indices near 100F) and thunderstorm complexes late this weekend into early next week.

Heat/Humidity and MCS Chances Late Weekend

Most guidance (with the exception of the GFS) suggests the early weekend cold front will fully sweep through central IL, leaving Saturday mainly dry with lighter winds and slightly lower humidity. That should change quickly by Sunday, however, as southerly flow and increased heat & humidity return. Sunday and Monday will be the warmest, with highs reaching into the low 90s across the south/west portion of our CWA and areawide dew points in the mid 70s. Here, heat indices could top 100 degrees both afternoons. The LREF indicates 20-40% probabilities of exceeding 100F, mainly S of a Beardstown to Effingham line. The only exception to this heat risk would be if any thunderstorm cluster passes through to disrupt peak diurnal heating.

The synoptic pattern, featuring a 45-60 kt belt of W/NW flow across the upper Midwest, will dominate into much of next week. Occasional shortwaves are expected to traverse atop the ridge and into the area in this general timeframe, but nailing down the exact timing is impossible at this range. With daily MUCAPE of 2500-4000 J/kg and 25-35 kt of 0-6 km shear, storm complexes from these disturbances may materialize in the region. One or two could dive into central IL and pose a damaging wind threat. Though SPC has no official outlines for severe weather at this time, CSU-MLP guidance does highlight daily chances for strong- severe storms, highest on Sunday and Monday (15%+).

AVIATION /18Z TAFS THROUGH 18Z THURSDAY/

Issued at 1223 PM CDT Wed Aug 5 2026

A decaying area of showers with a few remaining isolated, embedded thunderstorms will move across central Illinois this afternoon. Ceilings are high based (above 050) and expect little if any impact to visibility with rain outside of the few embedded cores of convection. MVFR and possibly IFR ceilings will overspread central Illinois from the northwest late tonight into Thursday morning. Ceilings are expected to improve back to VFR from the south around midday Thursday.

ILX WATCHES/WARNINGS/ADVISORIES

None.