textproduct: Central Illinois

KEY MESSAGES

- Scattered thunderstorms are forecast overnight into Friday over central and southeast IL. There is a low (5-10%) chance for severe weather from Bloomington to Taylorville westward overnight, with locally damaging winds the main risk.

- Another round of thunderstorms is likely (70-80% chance) Sunday night through Monday. There is a 15-30% chance for severe weather with these storms on Monday and Mon evening.

DISCUSSION

Issued at 345 AM CDT Thu Apr 23 2026

The 08Z/3 am surface analysis shows near the WI/IA border into far northeast IL and far southern lower MI. Strong 984 mb low pressure was along the southern Saskatchewan and Manitoba province line (just north of ND) with a cold front extending southward to 995 mb low pressure along the western NE/KS border. Nearly clear skies across central/se IL with light south to SE to calm winds. Temps were in the mid 50s to lower 60s, while dewpoints were in the low to mid 50s.

The warm front to lift northeast into the Great Lakes today while the cold front pushed into far western Iowa into central KS by sunset. Increasing pressure gradient over IL during today to develop breezy south to SSW winds gusting 25-30 mph by late morning and afternoon, with some gusts to 35 mph especially from I-55 west. A fair amount of sunshine today with some thin cirrus clouds and few cumulus clouds with bases around 5k ft this afternoon. Warm highs in the lower 80s over much of CWA today. The gusty southerly winds could cause blowing dust in recently tilled fields as the 2 inch soil moisture has lowered to 25-30% over central and southeast IL.

The cold front to approach the IA/IL border by 12Z/7 am Friday with convection likely along and ahead of it. We have low pops of 20-30% over the IL river valley during mid/late evening, with increasing chances of convection from west to east during overnight as cold front approaches. SPC Day1 outlook has marginal risk (level 1 of 5) of severe storms for damaging winds from Bloomington to Taylorville west overnight tonight while the slight risk (level 2 of 5) of severe storms is west of IL over Iowa and nw MO where large hail and tornado threats will be. Most models show convection weakening as it tracks eastward over IL overnight as instability gets less. High chances of showers and thunderstorms Fri morning to start diminishing from I-55 west during Fri afternoon as cold front moves east across IL on Friday. We have a 20-30% chance of showers lingering in southeast IL during early/mid Fri evening as cold front exits IL. SPC Day2 has shifted the marginal risk of severe storms east of IL over central and eastern IN into Ohio and sw of IL over southern MO and west TN. Rainfall amounts are forecast to average quarter to half inch over area overnight into Friday though pockets up to 1 inch possible with thunderstorms. Mild lows tonight in the lower 60s, with cooler highs Friday in the lower 70s.

Cold front pushes se of the Ohio river by sunrise Saturday while weak high pressure settles into the upper MS river valley Sat morning and over the northern Great Lakes by dawn Sunday. This high should keep central/se IL dry Saturday through at least Sunday morning. The Illinois Marathon is taking place in Champaign IL on Saturday morning Apr 25th and should be nice weather for this outdoor event. Mostly sunny skies Saturday with some increasing clouds over the IL river valley later in the day. Highs Saturday and Sunday in the low to mid 70s with lows Sat night in the upper 40s/lower 50s.

A stronger weather system moving into the Central Plains Sunday night to have a warm front lifting ne toward IL late Sunday. This will bring 20-30% chance of showers and isolated thunderstorms to west central and sw IL Sunday afternoon (west of a Peoria to Lincoln to Effingham line) as skies become mostly cloudy on Sunday. Will see increasing chances of showers and thunderstorms during Sunday night as warm front moves closer to central IL by dawn Monday. Will then see cold front move eastward over IL by Monday afternoon and this could bring a better chance of strong to severe storms along with moderate to heavy rains. NBM has 50-80% chance of over 1 inch of rain over CWA Sunday night and Monday with highest amounts from I-72 south. Both the CIPS experimental analogs and CSU- MLP machine learning forecasts are showing a threat for severe across central IL on Monday.

SPC's Day5 just arrived and shows a 15-30% risk of severe storms across IL on Monday with the 30% risk from Quincy to Springfield to Shelbyville and Olney sw. Per SPC discussion... Additional thunderstorms are expected to develop along and east of an advancing dryline/cold front in an increasingly unstable atmosphere Mon afternoon. Diurnal heating of a boundary layer with low to mid 60s dewpoints should result in SBCAPE/MUCAPE values between 2000-3000 J/kg. Additionally, vertical shear will remain more than sufficient for supercells. All severe hazards will remain possible with this convection, with the greatest concentration of severe storms likely across the Mid Mississippi Valley where a 30% area was introduced.

Another day in the 70s on Monday and then dry and a bit cooler on Tuesday as weak high pressure settles into area. Highs generally in the mid to upper 60s Tue-Thursday with next chance of showers and isolated thunderstorms Wed afternoon into Thu especially over southern CWA. Turning even cooler later next week with below normal temperatures likely going into 1st part of May. The Climate Prediction Center (CPC) 8-14 Day Outlook for Apr 30-May 6 has a 50-60% chance of below normal temperatures over IL, and precipitation trending near normal over central IL.

AVIATION /12Z TAFS THROUGH 12Z FRIDAY/

Issued at 555 AM CDT Thu Apr 23 2026

VFR conditions are forecast to continue across the central IL airports through at least this evening. SSE winds under 10 kts at dawn to become breezy south to SSW winds by mid to late morning with gusts 25-30 kts by midday and continue through the afternoon. Breezy south to SW winds to gusts 20-25 kts after sunset tonight. A band of convection developing ahead of an approaching cold front approaching IL by dawn Friday, will bring possible MVFR ceilings/vsbys and WNW wind gusts 30-40 kts to PIA from 08-10Z and BMI and SPI from 09-11Z. This band of convection expected to weaken as it gets to DEC and CMI late tonight.

ILX WATCHES/WARNINGS/ADVISORIES

None.