textproduct: Central Illinois

KEY MESSAGES

- No major storm systems are expected to impact the region over the next week. As a result, the severe weather risk across central Illinois will remain low (less than a 5% chance) through next Saturday.

DISCUSSION

Issued at 345 AM CDT Sun May 24 2026

*** Lingering Showers Today ***

08z/3am surface analysis shows a weak cold front approaching the Illinois River, accompanied by a band of showers with a few embedded thunderstorms. Current forecast thinking is virtually unchanged from previous cycles with the exception of a slower eastward progression of the precip early this morning. Based on radar trends and a consistent signal from the HRRR/RAP, think the bulk of the showers will be between the Illinois River and the I-55 corridor by 12z/7am, then along/east of I-57 by 18z/1pm. A few showers/thunderstorms will likely linger south of I-70 through late afternoon before the precip finally shifts into the Ohio River Valley. Storm total rainfall will range from 0.10 to 0.25 with isolated pockets of greater than 0.25.

*** Unsettled Week Ahead ***

After a dry day on Monday, an upper-level blocking pattern will develop across the eastern CONUS...featuring a high over the Upper Midwest and a low over the Deep South. The low will slowly pivot northward through the middle of the week while the high gradually strengthens and builds southward. The main question continues to be how far north precip associated with the low will spread and how quickly it will get shunted back southward later in the week. A good deal of model spread still exists at that time range: however, it is becoming increasingly clear that the wettest period across central Illinois will be Tuesday night through Wednesday night. After that, synoptic subsidence and dry N/NE flow will push the best rain chances further southward into the Ozarks and Ohio River Valley. Current forecast features likely to categorical PoPs (60-80% chance) for showers/storms Tuesday night into Wednesday with much lower PoPs (20-40% chance) lingering into Thursday and Friday. Think these will eventually be dropped once the NBM catches up to current trends. While rain is in the forecast, the lack of a strong system and overall weak instability/shear will prevent severe weather development throughout the entire forecast period. As a result, the latest machine learning algorithms feature little to no chance (less than a 5% chance) for severe weather across central Illinois through at least next Saturday.

AVIATION /12Z TAFS THROUGH 12Z MONDAY/

Issued at 600 AM CDT Sun May 24 2026

A band of showers with a couple embedded thunderstorms has formed just west of the I-55 corridor early this morning. The showers are moving northeastward and will gradually shift east of I-55 by 14z. While the bulk of the activity will lift N/NE of the central Illinois terminals by mid-morning, a few lingering showers will continue to be possible through about 17z...especially at KBMI/KDEC/KCMI. Once the precip departs, winds will veer to N/NW at 5-10kt and skies will clear from west to east this afternoon. As high pressure moves overhead, winds will become nearly calm tonight. Will need to keep an eye on possible fog formation, especially across east-central Illinois where skies will remain cloudy longest and thus less boundary layer mixing will occur this afternoon. An initial glance at the CAMs shows a band of low visbys forming directly beneath the ridge axis after midnight along/south of the I-72 corridor. Have therefore included a TEMPO group for 2-4 mile fog between 08z and 12z at all sites except KPIA.

ILX WATCHES/WARNINGS/ADVISORIES

None.