textproduct: Central Illinois

KEY MESSAGES

- There is a marginal risk (5-15% chance) for severe weather along and south of Paris to Shelbyville line through 8pm today. The primary hazards will be large hail and damaging winds, although an isolated tornado cannot be ruled out especially from highway 50 south. Moderate to heavy rains of 1-2 inches in southeast IL tonight into Thu morning and could lead to locallized flooding. - After a windy and very warm day with highs soaring into the middle to upper 70s Friday, there is a Slight Risk (15-30% chance) for severe weather west of the I-57 corridor Friday night as a cold front approaches from the west.

DISCUSSION

Issued at 200 PM CST Wed Mar 4 2026

The 20Z/2 pm surface map shows 1013 mb low pressure over central MO (just west of Kaiser/Lake Ozark MO), with its warm front extending into southern IL, just north of I-70. Sharp temperature contrast across this boundary with temps in the lower to mid 40s from I-72 north and upper 50s and lower 60s from I-70 south where dewpoints were in the upper 50s to near 60F. Large area of showers with a few embedded thunderstorms was slowly lifting ne toward a Rushville to Springfield to Shelbyville and Effingham line. Stronger line of convection with more lightning was south of St Louis. Widespread fog continued over central IL north of the warm front with areas of dense fog from Quincy and Lincoln and Champaign south to near Litchfield and Tuscola. Also have a low stratus deck over central and northern IL (south of I-80 and north of I-70) with cloud bases of 200-500 ft. Precipitable water values were 1-1.35 inches from Quincy to Peoria to Pontiac south with highest values south of I-70. MUCAPES were 400-800 j/kg south of a Paris to Springfield line and 1000-1500 j/kg in southern IL south of I-64. Effective Bulk shear values of 40-55kts in southern IL from Pittsfield to Fairfield (Wayne county) south.

A 564 decameter 500 mb low was near the western NE/KS border with a weaker mid level trof/short wave in eastcentral MO moving toward MS river of west central and sw IL. Latest CAMs show short wave lifting into southeast IL by sunset and likely have some convection ahead of it affecting central and especially southeast part of CWA into early evening. Still have marginal risk of severe storms from Shelbyville to Paris south of mainly large hail risk, with far southern CWA having risk of tornadoes and damaging winds. The stronger instability is south of CWA where strongest storms are a larger risk. PW values of 1.25-1.4 inches in southeast IL also support risk of moderate to heavy rains in southeast IL. This area did not have quite as much rainfall since Tue morning as areas north of I-70 to along I-72 where 2-3.5 inches of rain occurred. But think we will issue a flood watch for southeast IL tonight into mid Thu morning. We also have a river flood warning for the Little Wabash river at Clay City, with Lawrenceville on the Embarras river forecast to crest just shy of flood stage Fri evening. Another disturbance lifting ne out of central MO into central IL overnight to likely bring a 2nd round of convection to the area late this evening and overnight with some moderate rains and possible small hail.

Latest CAMs shows fog becoming more widespread and denser in central IL during this evening especially between the IL river and I-70. Have increase mention of fog with dense fog included, and may need to watch for possible dense fog advisory.

Showers to diminish from sw to ne during mid/late Thu morning, then a lull expected in precipitation Thu afternoon/evening. A warm front lifting northward over central IL overnight Thu night into mid Fri morning could bring a chance of showers and isolated thunderstorms. The breezy south to WSW winds gusting 25-35 mph by Fri afternoon to bring warmer highs in the mid to upper 70s and be our warmest day over much of CWA since Nov 14-15th.

SPC Day3 continues slight risk of severe storms Fri night mainly after midnight Fri night west of I-57 with marginal risk from I-57 east. QLCS tornadoes possible from IL river valley west into IA/MO with large hail and damaging winds also risk. Could see lingering chances of showers and isolated thunderstorms in eastern IL Sat morning as cold front passes through. Highs Sat range from upper 50s and lower 60s from I-55 west to the mid to upper 60s in eastern IL with more Pacific air moving into IL instead of a Canadian air mass. Weak high pressure 1020-1024 mb settles into the mid MS river valley Sunday providing a break from the active weather Sat night into daytime hours on Monday.

A strong cutoff 500 mb low forms near Baja of California this weekend and lifts into west Texas by dawn Wed. This system will eject a strong storm system ne form the southern plains into IL around Tue/Tue night. This will likely bring our next round of showers and thunderstorms along with risk of strong to severe storms and moderate/heavy rains. SPC Day 7 outlook has risk of severe storms sw of IL but this may expand ne into part of our area with time. Warm air ahead of this storms system with highs in the low to mid 70s Monday and Tuesday with breezy SSW winds.

07

AVIATION

(For the 18z TAFs through 18z Thursday Afternoon) Issued at 1121 AM CST Wed Mar 4 2026

Widespread IFR/LIFR conditions will prevail the next 24 hours, with ceilings likely to stay around 500 feet or less much of the period. Some slow improvement of dense fog in central Illinois is expected early this afternoon, but probabilities of visibility dropping below a mile again overnight are around 40% per latest NBM guidance.

Periods of showers and a few thunderstorms are expected as well. Confidence in thunder around KPIA/KBMI is much lower, but PROB30 groups have been included further south for mid/late afternoon, as well as between about 06-12z.

Geelhart

ILX WATCHES/WARNINGS/ADVISORIES

None.