textproduct: Central Illinois

KEY MESSAGES

- SW winds gusting 30-40 mph this afternoon east of the IL river will cause blowing dust in open/rural areas that have recently been tilled. Continued the Blowing Dust Advisory until 6 pm east of the IL river and north of I-70. Blowing dust can result in localized, sharply reduced visibilities for motorists to be use caution if traveling this afternoon in central IL.

- Isolated to scattered showers and thunderstorms east of I-55 this afternoon, and become more widespread tonight. There is slight to marginal risk for large hail and damaging wind gusts, mainly from 7 pm to 1 am tonight. The higher risk of severe storms this evening (slight risk with level 2 of 5) is from Shelbyville to Paris north.

UPDATE

Issued at 1045 AM CDT Mon May 4 2026

Updated the forecast to adjust chances of showers and thunderstorms the rest of today. Continued Blowing Dust Advisory from 11 am to 6 pm southeast of the IL river and north of Effingham, Cumberland and Clark counties. SW winds 10-20 mph and gusts of 20-30 mph to increase this afternoon with gusts 30-40 mph possible especially over east central IL per latest HRRR 10M wind gust forecast. This could lead to blowing dust in recently tilled fields between the IL river and I-70, especially in areas that stayed dry so far since last night.

Radar mosaic shows a band of showers and thunderstorms from Springfield to Decatur to Paris south to near I-70 and tracking eastward quickly at 50 mph. There is a subtle short wave tracking quickly eastward with this convection along with 30-40 kt sw low level jet into central IL. This convection should weaken next few hours as LLJ weakens and short wave moves into Indiana. However more convection expected to develop late this afternoon and early evening mainly se of I-55, and also during this evening over nw CWA as cold front moves into nw IL during this evening. SPC Day1 outlook continues marginal risk of severe storms for large hail and damaging winds over much of IL for mainly late afternoon and evening hours, with areas from Canton to Decatur to Taylorville sw upgraded to a slight risk of severe storms. Breezy sw winds and some sunshine to warm temperatures to 75-80F degrees.

DISCUSSION

Issued at 245 PM CDT Mon May 4 2026

We have recently received a few reports of blowing dust since 130 pm over southeast parts of Logan and into Macon counties with sw winds gusting as high as 30-40 mph. Will continue the Blowing Dust Advisory until 6 pm east of the IL river and north of I-70.

Radar mosaic at 230 pm shows some light southeast in southeast IL from I-70 south while a band of thunderstorms was sw of Vandalia to south side of St Louis metro and tracking eastward across southern IL. A fair amount of sunshine nw of a Rantoul to Taylorville line at mid afternoon helping warm temperatures up into the mid to upper 70s. Mid to upper 70s also in far southeast IL from Robinson to Olney to Fairfield se while cooler 65-72 degrees over cloudier areas of eastern IL. The 19Z/2 pm surface map shows a cold front over southeast parts of WI/Iowa into far nw MO and central KS. IL was in the warm sector so far. We have some capping over central and southern CWA at mid afternoon that has keep thunderstorms below severe levels so far despite MUCAPES of 1-2k j/kg and MLCapes 500-1k j/kg and effective bulk shear values of 35-50 kts.

Cold front to push se into nw IL during this evening and will see sw LLJ 35-40 kts into central IL helping to develop scattered convection during this evening and a few cells could appear late afternoon/early evening in eastern IL and getting into Knox and Stark and nw Marshall counties by sunset and shifting se into central IL during this evening. SPC Day1 outlook has slight risk over much of central IL from Shelbyville to Paris northwest and marginal risk southeast. SPC has 2% risk of tornadoes in slight risk area, while 5-15% risk of damaging winds over CWA (highest ne of BMI). Also have 5-15% risk of large hail over area, with the 15% risk in slight risk area. Also have level 1 for 2 inch or larger hail over west central IL into northern MO for late afternoon and evening. Cold front to press se toward IL river valley early overnight and into southeast IL late Tue morning to midday Tue. Chance of severe storms shift south of CWA on Tue though we have marginal risk of excessive rainfall in southeast IL where 1-2 inches possible.

Showers to diminish from nw to se during Tue night wile just slight chances of showers on Wed mainly south of I-74. Much cooler Tue with the clouds and showers, with highs 55-60F over central IL and 60-65 in southeast IL from I-70 se. Lows in the lower 40s central IL Tue night and mid 40s southeast IL. Cool highs Wed in the mid to upper 50s with even cooler lows in the upper 30s in central IL and lower 40s in southeast IL. A large mid/upper level trof over the Midwest/Great Lakes and Ohio river valley Thu could keep slight chances of light rain showers around though we currently have pops less than 20% on Thu. Highs Thu 60-65F, mildest over west central IL. A northern stream short wave trof dives se into the area on Friday afternoon bringing a chance of showers and isolated thunderstorms Fri afternoon and Fri evening. Breezy sw winds on Friday warms temps up to 65-70F.

Saturday currently looks dry and comfortable with highs in the low to mid 70s. But another another disturbance moving in overnight Sat night and Sunday (Mothers Day) to return chances of showers and thunderstorms.

AVIATION /18Z TAFS THROUGH 18Z TUESDAY/

Issued at 1255 PM CDT Mon May 4 2026

A band of showers and isolated thunderstorms was se of BMI and went to Champaign and Danville areas and to affect CMI airport next hour or so with possible brief MVFR vsbys. Isolated convection to develop late this afternoon and early evening and become more scattered later this evening into overnight as ceilings lower to MVFR from I-55 se. Showers to diminish from the west and nw during mid to late Tue morning from I-55 nw and likely continue at CMI and DEC into Tue afternoon. Breezy SW winds 15-22 kts with gusts 25-32 kts this afternoon could cause blowing dust at CMI and BMI but recent rainfall at CMI may limit that. SSW winds to diminish to around 10 kts during this evening and switch north to NNE between 06Z-10Z overnight as cold front moves se through central IL, starting at PIA and last at DEC and CMI, and continue into Tue.

ILX WATCHES/WARNINGS/ADVISORIES

Blowing Dust Advisory until 6 PM CDT this evening for ILZ031- 037-038-041>048-050>057-061.