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 very low (less than a 5% chance) through next Monday.

DISCUSSION

Issued at 341 AM CDT Tue May 26 2026

08z/3am water vapor imagery shows an upper low spinning over the ArkLaTex region. With deep-layer moisture flowing northward from the Gulf ahead of this system, showers have spread as far north as the Ozarks into western/southern Kentucky. As the precipitation continues to lift slowly northward, it will eventually encounter synoptic subsidence and a drier airmass beneath a surface ridge axis across central Indiana/Illinois. As a result, the northward progress of the rain will be slow...with most CAMs confining any showers to locations along/south of I-70 through this afternoon. Further north, am expecting mostly cloudy and dry conditions. High temperatures will range from the upper 70s along/south of I-70 to the middle 80s north of the I-72 corridor.

The low will continue its gradual trek northward tonight: however, it will be weakening as it does so. 00z May 26 models are all in good agreement concerning the eventual northern extent of showers tonight into Wednesday...with consensus placing it near a Rantoul to Jacksonville line. The main forecast concern is rainfall amounts as a few models indicate bands of showers blossoming and becoming quasi-stationary across portions of east-central Illinois late tonight into Wednesday morning as the low approaches. The 06z HRRR shows a few amounts over 1 inch from Paris/Marshall southwestward to near Effingham. Meanwhile the 00z HREF mean QPF features pockets of 0.75-1.00 across this general area and perhaps as far N/NW as Tuscola and Shelbyville. The NBM is considerably lighter with amounts of only around 0.25. At this point, will focus highest PoPs (40-50% chance) south of a Danville to Shelbyville line with rainfall of 0.25 to 0.50. Will need to keep a close eye on future model data in case rainfall needs to be boosted in this area. Further northwest along/NW of I-55, little to no rain is expected.

As upper ridging builds over the Upper Midwest, it will shunt the remnants of the low southward and allow a return to dry weather across the board Wednesday night through the end of the week. After that, the synoptic models indicate surface high pressure over the Great Lakes region will keep central Illinois dry through early next week as short-wave energy remains S/SW of the area. Seasonal temperatures in the upper 70s and lower 80s are anticipated.

AVIATION /18Z TAFS THROUGH 18Z WEDNESDAY/

Issued at 1216 PM CDT Tue May 26 2026

VFR conditions are forecast through the period. Cirrus shield persists across much of the area, with some diurnal Cu developing near and south of the I-72 corridor. Main concern this period is scattered showers and associated lower ceilings, which are most likely south of I-72. Based on this, included a PROB30 shower group at KDEC/KCMI, but not other sites. MVFR and even IFR ceilings are possible across southeast Illinois (south of I-70) overnight into Wed AM, but for now indications are that these lower clouds will stay south of the terminals.

ILX WATCHES/WARNINGS/ADVISORIES

None.