textproduct: Central Illinois

KEY MESSAGES

- No significant weather is expected across central Illinois over the next week.

DISCUSSION

Issued at 145 PM CDT Wed Sep 23 2026

Current Conditions and Synoptic Overview: Water vapor and upper air analysis continues to show a rather messy/convoluted pattern with a blocking pattern across the CONUS. An upper level low continues to slowly move east across Indiana. A large ridge across the Central Plains was also slowly moving east. The 12z ILX sounding showed a decent amount of saturation in the low levels but the column then dries out above 700mb. The upper low and moisture continues to allow for scattered to broken cumulus clouds around 2-4kft. Earlier this morning there were even a few mPING reports of drizzle given some weak lift and lack of cloud ice. A few breaks in the clouds have allowed for temps to reach the mid/upper 60s to around 70 early this afternoon.

Through Friday: Latest HREF/REFS guidance continues to favor more clouds versus sun over the next few days as that low pressure will be slow to slide east and additional energy moves in from the west. Other than a very rogue area of drizzle or sprinkles, most locations will remain dry. Have generally trended closer to the consensus of high res models which keeps highs a little lower than the NBM with most locations reaching the low 70s each afternoon. The northeast flow should keep dews and therefore overnight lows in the 50s.

Low Weekend Rain Chances: With the upper low moving east of the area Friday, additional energy looks to slide up and over the ridge across Missouri during the weekend. With high pressure remaining over the Great Lakes, drier/stable air will prevail over Illinois which will inhibit much precip from making it very far east into the state. Ensemble cluster analysis generally suggests that the higher rain chances will also struggle to make it into the western tier or two of counties where a 15-30% chance of rain exists Saturday. Clouds on Saturday should keep temps a little lower than previous days with some areas remaining in the upper 60s. Confidence is medium to high that most locations will remain dry this weekend.

Higher Rain Chances Around Next Tuesday/Wednesday: In between the weekend system and early next week there will be little if any rain chances with gradually increasing temperatures. Ensembles are coming into agreement on an amplified trough moving into the region by Tuesday/Wednesday of next week. NBM PoPs are already in the 50-60% range and is also supported by all of the ensemble clusters. As far as significant hazards go, the Ensemble Situational Awareness Table is not showing anything anomalous at this time and the area is not outlooked in any hazard/threat areas.

AVIATION /00Z TAFS THROUGH 00Z FRIDAY/

Issued at 605 PM CDT Wed Sep 23 2026

MVFR ceilings over eastern IL and IN are forecast to spread west into central IL this evening, and persist into midday Thursday before starting to scatter out. Confidence is low that KPIA will drop to MVFR as most models keep the lower cloud deck southeast of that terminal, so kept them VFR. There is around a 30% chance that IFR ceilings develop at KDEC-KCMI late tonight. Northeast winds will persist near/under 10 kt.

ILX WATCHES/WARNINGS/ADVISORIES

None.