textproduct: Central Illinois

KEY MESSAGES

- Severe weather is possible Sunday afternoon and evening, with the greatest threat near and east of Interstate 55. Damaging winds potentially exceeding 75 mph and a few tornadoes are the primary hazards.

- A sharp transition from rain to snow occurs Sunday night behind a strong cold front, accompanied by wind gusts over 40 mph and rapidly falling temperatures. Snow accumulations are possible with the highest probabilities of exceeding 2 inches focused near and west of the Illinois River.

- Subfreezing high temperatures and minimum wind chills between 0 and -10 degrees are expected Monday and Tuesday mornings before a significant warming trend takes over for the last half of the new week.

DISCUSSION

Issued at 217 PM CDT Sat Mar 14 2026

Surface analysis early this afternoon shows surface high pressure centered over lower Michigan/Ohio with breezy east-southeast winds across central Illinois. Mostly cloudy skies have kept temperatures a few degrees cooler than originally anticipated with highs expected to top out in the upper 40s to middle 50s. A deepening surface low will track from the central Plains into the Great Lakes Region on Sunday, bringing a period of impactful weather Sunday through Monday.

Strong southerly winds will develop out ahead of an approaching cold front on Sunday with high probabilities for gusts to exceed 40 mph through Sunday night. A warm, moist airmass will advect northward during the day with high temperatures expected to climb into the 60s to low 70s. Periods of showers and thunderstorms will begin as early as mid to late morning, though the threat for strong to severe storms increases later Sunday afternoon/evening with the arrival of the cold front. The latest suite of CAMs shows a line of thunderstorms developing in west-central Illinois between 19-21Z as a strengthening mid-level jet begins rounding the base of a trough, further increasing deep layer shear. Although dewpoints in the 50s will limit instability (<1000 J/kg MLCAPE), robust deep layer shear and strong kinematics will favor a squall line/QLCS event, with damaging winds and tornadoes being the primary hazards through the evening. The highest threat will be east of I-55 where an Enhanced risk for severe storms (level 3 of 5) is in place.

Behind the front, strong cold air advection will transition precipitation to snow Sunday night within the lows deformation zone. Accumulating snow continues to be a possibility with about a 50-70% chance for seeing at least 2 inches near and west of the Illinois River, with lesser amounts further east and southeast. Strong west- northwest winds on the backside of the departing low will significantly reduce visibility where snow is falling, resulting in hazardous travel conditions. A winter weather headline may be needed for counties near and west of the Illinois River where the highest accumulations are forecast.

Much colder air filters in behind the system for Monday and Tuesday with ECMWF EFI showing values around -0.8, which indicates an unseasonably anomalous event. Temperatures will be coldest Monday night with values falling into the single digits to teens. Breezy winds during this period will send wind chills below zero for western parts of the state Monday morning and for most Tuesday morning.

A quick hitting clipper system may bring another shot of wintry precipitation Tuesday night, possibly resulting in minor snow accumulations. Temperatures will moderate by midweek then surge well above normal late in the week into next weekend as upper ridging over the western CONUS amplifies, allowing mid-level heights to quickly rise over the Midwest states.

NMA

AVIATION

(For the 06z TAFs through 06z Sunday Night) Issued at 1235 AM CDT Sun Mar 15 2026

All sites will start as VFR with mid level cigs around 12-15kft. HiRes models show a narrow line of sub severe showers and scattered storms moving across all sites in the morning. Cigs could drop to MVFR around 2.5kft with these storms and have a 2hr PROB30 group at PIA and BMI. Only VCSH for SPI, DEC, and CMI with no MVFR cigs. All sites will have MVFR cigs for late morning and afternoon, but when main line of storms develops and moves through each site, have a 3hr TEMPO group at each site with very high winds, vis around 1sm and cigs below 1kft. After storms, rain/snow mix is possible at all sites, but have no reduction in vis and lower MVFR cigs. Winds will continue to increase in speed out of the southeast, then become southerly for most of the day, then westerly after the front/storms moves through. Gusts will be very high just ahead of the afternoon storms and behind in the evening.

Auten

ILX WATCHES/WARNINGS/ADVISORIES

Wind Advisory from 10 AM this morning to 7 AM CDT Monday for ILZ027>031-036>038-040>057-061>063-066>068-071>073.