textproduct: Central Illinois

KEY MESSAGES

- An unsettled period of weather is on tap through the middle of next week. While rain chances are in the forecast nearly every day, there will be plenty of dry periods as well, especially over central IL from Friday night through Sunday morning.

- The risk for severe weather returns Monday afternoon through Wednesday. SPC severe weather probabilities are greater than 15% across west central and northwest IL Monday afternoon and Monday evening, over central and northern IL Tuesday afternoon into Tuesday night and over much of IL on Wednesday.

DISCUSSION

Issued at 245 PM CDT Thu Apr 9 2026

At 19Z/2 pm, a frontal boundary was over northern IL, just north of the Galesburg airport, near Lacon airport and just north of Kankakee airport. The front extended back over nw MO and along the KS/NE border to 1010 mb low pressure in eastcentral CO. Radar mosaic shows isolated showers near the boundary close to I-80 with more widespread showers in central/sw Iowa into eastern Nebraska. A fair amount of sunshine over areas se of the IL river with scattered high base cumulus clouds from I-72 northward and ample sunshine south. Mid/high clouds were spreading into west central and nw IL from Iowa and northern MO. Mild temps were in the lower 70s nw of the IL river and mid 70s to near 80F se of the IL river with breezy sw winds gusting 20-30 mph.

A short wave over the Dakotas will track eastward into the northern Great Lakes tonight, pushing the front se through the IL river valley by early overnight and thru rest of central IL later tonight into Fri morning, and thru southeast IL by mid Fri afternoon. Increasing low level jet and moisture to help develop more widespread convection over nw IL early this evening, and push se into the IL river valley later this evening and early overnight, getting south of I-72 around 3-4 am. The convection to diminish/become more scattered later tonight as it pushes south of I-72 and into southeast IL by Fri morning. Chances of showers and isolated thunderstorms lingers south of I-72 during Friday afternoon and over southeast IL into early to mid Fri evening as front nears Ohio river by sunset Fri. Rainfall amounts of quarter to half inch with local amounts of half to 1 inch over nw CWA, a tenth to quarter inch over heart of central IL, and generally around a tenth inch or less in southeast IL. Lows tonight in the upper 40s to around 50F from Peoria nw and mid to upper 50s from Quincy to Lincoln to Rantoul south. Highs Friday range from lower 60s north of Lincoln and lower 70s se of I-70 (near 75F in Lawrence county).

1028-1032 mb high pressure to build into the central Great Lakes by lower MI by dawn Saturday and move into southern New England by dawn Sunday. Cool ne flow on Friday night to bring a seasonably cool night with lows in the low to mid 40s, with upper 30s possible from I-74 ne. Highs Saturday similar to Friday's highs, with low to mid 60s central IL and upper 60s/lower 70s in southeast IL. We have 20-30% chances of showers over western/sw half of CWA on Saturday with isolated thunderstorms possible Sat afternoon just sw and west of CWA.

As high pressure shifts further east of IL during Sat night, a warm front to lift ne over the area with breezy south to SW winds on Sunday gusting 25-35 mph and some spots reaching 40 mph north of I-70. Warmer highs in the upper 70s to around 80F return on Sunday. We have convection chances Sunday afternoon and Sunday evening west of I-57 with highest pops (40-60%) west of the IL river. Higher chances of convection 50-60% move into eastern IL too overnight Sunday night into Mon morning as a disturbances lifts through. Best chance of severe storms Sunday afternoon/evening appears to stay well sw of IL then where better instability will be.

Warmer and more humid air arrives early next work week, with highs in the lower 80s Monday and low to mid 80s Tue. Dewpoints in the mid 50s to around 60F Sunday rise into the the 60s (even a few spots near 70F) on Mon/Tue. Convection chances appear to become more isolated during Monday afternoon into Tue afternoon but with increase instability may see a few strong to severe cells especially over west central and nw IL. A better chance of convection to arrive Tue afternoon into Wed and SPC has much of central IL in 15% risk or higher on Tue afternoon/Tue night and much of IL has 15% risk or higher of severe storms on Wed. Warm temperatures continue Wed/Thu with highs in the mid 70s to near 80F.

AVIATION /18Z TAFS THROUGH 18Z FRIDAY/

Issued at 1255 PM CDT Thu Apr 9 2026

VFR conditions should continue across the central IL airport through at least this evening. A frontal boundary across northern Illinois (just north of Galesburg and Lacon) will push southward to near PIA by sunset, with SW winds near 10 kts and gusts 15-20 kts becoming variable around 5 kts this evening. Breezy sw winds 12-18 kts with gusts 22-27 kts over rest of central IL airports this afternoon to diminish a bit by early evening but still few gusts to 20-25 kts tonight. As weak low pressure passes by PIA around 06Z, this will push the front further se through I-55 by 08-09Z and DEC and CMI by 10-12Z. Will likely see a band of showers and isolated thunderstorms accompany the front overnight until mid Friday morning with MVFR ceilings developing late tonight/Fri morning (possibly IFR at PIA and BMI). Winds to shift NW to north during Fri morning at 8-13 kts.

ILX WATCHES/WARNINGS/ADVISORIES

None.