textproduct: Central Illinois

KEY MESSAGES

- Heat Advisory remains unchanged today; high temperatures will reach around 90 degrees with peak heat indices near 100 degrees, though lingering anvil debris and upper-level wildfire smoke introduce minor temperature uncertainty.

- Severe weather threat late this afternoon and evening remains conditional across central and northeast Illinois. Isolated damaging winds, hail, and a localized tornado risk may evolve if our capped environment breaks.

- Higher-confidence, high-end severe potential develops by midday Tuesday near the I-80 and I-74 corridors where extreme wind gusts (70+ mph) are plausible.

- Active "ring-of-fire" pattern maintains periodic shower and thunderstorm chances through late week and the weekend.

DISCUSSION

Issued at 557 AM CDT Mon Aug 10 2026

VFR conditions should persist throughout this TAF period despite occasional passing clouds. Winds will remain mostly from the south around 10 kts, though could become variable should scattered thunderstorms develop over a regional terminal this afternoon. Ultimately, this possibility remains too low to mention in the TAFs, but trends will be monitored and amendments will be made as needed.

A slightly higher --though still low-- probability for scattered thunderstorms exists this evening. This has been covered by a blanket PROB30 group for -TSRA progressing from west to east between 04z-12z.

AVIATION /18Z TAFS THROUGH 18Z TUESDAY/

Issued at 1247 PM CDT Mon Aug 10 2026

A BKN-OVC mid-level cloud deck at around 15,000ft continues to shift eastward across central Illinois early this afternoon. A few breaks have formed in the overcast and this should allow FEW-SCT diurnal Cu at around 2500ft to develop as the afternoon progresses. Aside from a stray shower/storm, it appears the emphasis for convective development this afternoon and evening will be further north along the I-80 corridor where a Cu-field has already formed. Most CAMs keep this activity well north of the central Illinois terminals, so have opted to keep the TAFs dry through tonight. There is growing confidence that a cluster of strong to severe convection will develop across northern Iowa late tonight, then track E/SE across northern Illinois Tuesday morning. While model solutions vary, it appears the main thrust of the storms will stay along I-80. However, the trailing end of the convection will likely graze the I-74 corridor. As such, have included a PROP30 group for thunder between 15z and 18z at KPIA. KBMI/KCMI may possibly be impacted as well, but that would be after 18z.

ILX WATCHES/WARNINGS/ADVISORIES

Heat Advisory until 7 PM CDT this evening for ILZ040-047>052- 061>063-066>068-071>073.