textproduct: Central Illinois

KEY MESSAGES

- There is a Slight Risk (level 2 of 5) for severe weather areawide today. While all severe weather hazards will be possible, damaging wind gusts in excess of 60 mph will be the most likely.

- Additional thunderstorms will develop along an advancing cold front on Tuesday, with a Slight Risk (level 2 of 5) for severe weather in areas east of Interstate 55. Once again, damaging wind gusts in excess of 60 mph will be the most likely hazard.

..Midweek Clearing Followed by a Wet Weekend Outlook

Wednesday through Thursday: A welcome pattern shift occurs mid- week as a cooler, significantly more stable post-frontal regime takes hold. Continental high pressure building into the Midwest will clear skies and lower humidity levels, offering a brief reprieve from the active weather.

Friday through Sunday: The dry spell will be short-lived. Global deterministic models are in notably better agreement, signaling a return to a wetter, unsettled pattern by late week. As the surface high pressure slants eastward, a potent mid-level shortwave will advance across the central U.S. A steady plume of Gulf moisture combined with a series of minor shortwave impulses lifting northeast from the Southern Plains will keep central Illinois susceptible to multiple rounds of scattered showers. While weak kinematic profiles should heavily restrict the overall severe weather risk, a gradual build-up of instability over the weekend will support widespread thunderstorm development.

AVIATION /12Z TAFS THROUGH 12Z TUESDAY/

Issued at 519 AM CDT Mon May 18 2026

A line of thunderstorms approaching from the west is expected to reach KPIA by 13Z, KSPI and KBMI by 15Z, and KDEC/KCMI by 16Z this morning. A three-hour TEMPO group has been included to account for IFR visibilities during the storms, with scattered showers likely to linger for several hours afterward under generally VFR conditions. Brief periods of degraded conditions are possible within the most intense storm cells.

South winds are forecast to increase to 15-20 kts this morning, with gusts reaching 25-30 kts. Low-level wind shear is anticipated late tonight at regional terminals as 50 kt southwest winds return aloft. An additional round of thunderstorms will move in from the west overnight before sunrise; a PROB30 group has been added to address this potential.

ILX WATCHES/WARNINGS/ADVISORIES

None.