textproduct: Central Illinois

KEY MESSAGES

- The stretch of warm weather is expected to last through at least Friday, with daily temperatures climbing into the upper 70s and lower 80s, with mid 80s likely on Tuesday and Friday. Breezy south to southwest winds, occasionally reaching 25-35 mph, will accompany this warm period this week.

- This week will be riddled with thunderstorm potential. Tuesday afternoon and evening, Wednesday afternoon and evening, and Friday night into Saturday morning currently exhibit the highest probability (15-30%) of severe weather.

- There is also potential for substantial accumulative rainfall throughout the week, with our multi-model ensemble predicting a medium (40-60%) chance of exceeding 2 inches through Saturday in areas along and north of I-72.

DISCUSSION

Issued at 230 PM CDT Mon Apr 13 2026

A subtle mid level short wave lifting ne has scattered convection ne of I-74, with a few strong to severe storms ne of Pontiac with hail where unstable air mass (MUCAPES over 2000 j/kg) and steep mid level lapse rates with 30-40 kt bulk shear values. SPC day 1 update has marginal to slight risk from I-72 north this afternoon for mainly large hail, though the better risk of severe storms appears to have passed ne of CWA at mid afternoon. Still could be a few isolated strong to locally severe cells north of I-74 next few hours for mainly hail chances. Latest CAMs do not show much convection over CWA tonight through early Tue afternoon. Our next best chance of convection will drop down from WI and northern IL into northern CWA during Tue evening and into more of central IL overnight Tue night into Wed morning. SPC Day2 outlook has Marginal risk along and north of I-70 for late Tue afternoon and Tue night, with slight risk along and north of I-72 and enhanced risk far northern CWA north of a Galesburg to Henry line. Areas north of Peoria are outlook for more significant risk of larger hail 2 inch or bigger and EF2 or stronger tornadoes. The 10% or higher risk of tornadoes (EF2 or stronger) just just north of Knox and Stark counties. Very warm highs 82-87F on Tue with moist dewpoints in the 60s and breezy SSW to SW winds gusting to 30 mph. Will be approaching record highs in upper 80s in a few locations Tue and again Friday.

The main cold front is nw of IL much of this work week. Surface low pressure ejects ne into the upper MS river valley late Wed afternoon and brings the cold front se into central IL during Wed night. Will likely see a round of showers/thunderstorms along and ahead of this front Wed afternoon into Wed night. SPC Day3 outlook has marginal to slight risk of severe storms Wed afternoon/evening, with the slight risk nw of the IL river. Highs Wed in the upper 70s/lower 80s, with mid 80s far se IL by Lawrenceville.

Models differ with convection chances on Thu as Ecmwf keeps high chances of showers/thunderstorms on Thu while NAM mainly has pcpn in southeast IL and GFS and GEM in between. NBM keeps fairly high pops around Thu though severe risk looks low. Thu night and Fri morning looks drier/lull in convection chances. Deepening mid/upper level trof over the Rockies last this week to eject stronger storm system into the Midwest by Fri night into Sat with passage of a stronger cold front. This will likely be our next best chance of convection Fri night into Sat and could be risk of strong to severe storms too, though not in an official SPC outlook yet during this time frame. Much cooler air arrives Sat night and Sunday behind front with highs Sunday 55-60F and lows Sat night in upper 30s/lower 40s and mid to upper 30s Sunday night.

AVIATION /06Z TAFS THROUGH 06Z WEDNESDAY/

Issued at 1205 AM CDT Tue Apr 14 2026

A weak disturbance crossing the region late tonight will bring a 1-2 hour window of low -TSRA chances to central IL. The higher probabilities of this occurring are near/north of the I-74 corridor where a PROB30 group was included. Otherwise, as diurnal heating commences, BKN MVFR ceilings are forecast to develop, especially at KPIA-KBMI-KCMI, with lower probabilities to the south. These should rise above 3k feet by midday. An isolated storm can't be ruled out this afternoon but probabilities are too low to mention in the TAF. Southwest winds will remain gusty through the period, near 25 kt at times.

ILX WATCHES/WARNINGS/ADVISORIES

None.