textproduct: Central Illinois

KEY MESSAGES

- A Blizzard Warning remains in effect for Knox and Stark Counties and a Winter Weather Advisory for the IL river valley from Cass, Menard, Logan and McLean counties northwest until 1 pm today. A wind advisory remains in effect for central and southeast IL until 10 am this morning for wind gusts up to 45 mph at times into mid morning.

- Subfreezing high temperatures today and Tuesday, with minimum wind chills of zero to 5 below over the IL river valley this morning, and zero to 10 below zero over central IL from I-70 north tonight into mid Tuesday morning.

- A clipper system will likely bring a period of light snow to central and southeast IL during Tuesday night. Generally less than 1 inch of snow is expected south of I-74, with around 1 inch of snow possible from I-74 north.

DISCUSSION

Issued at 400 AM CDT Mon Mar 16 2026

The 08Z/3 am surface map shows strong and still deepening 984 mb low pressure just east of Grand Rapids, MI with its cold front extending southward over western Ohio and into eastern KY/TN. A surface trof extended sw into northwest IN and southeast IL. Radar mosaic shows an area of light snow over and nw IL while more scattered light snow with some mix pcpn over southeast/southern IL. Light snow and gusty winds restricting vsbys to 1-3 miles from I-55 west with 1/2-1 mile over some airports west of the IL river like Quincy and Macomb. Strong west to nw winds of 20-30 mph with gusts of 30-40 mph had brought in much colder Canadian air. Temps range from upper 20s from I-55 nw to the mid 30s in southeast IL from Terre Haute to Salem southeast.

Strong low pressure to lift ne to near Alpena in far northeast lower MI by 18Z/1 pm today, and then toward Georgian Bay Canada by sunset. A strong mid/upper level trof moves east across IL during this morning keeping snow chances going at least into early afternoon. The brunt of our snow accumulations to occur through mid morning with 3-5 inches of total snow nw of the IL river and 1-3 inches from IL river se to near Champaign and Decatur, but the deformation band of light snow to linger over central/se IL through the morning, and still seeing some snow showers this afternoon over ne and eastern CWA. The snow squall parameter shows better chance of these snow showers over Indiana this afternoon but may affect eastern IL too with narrow 1 to locally up to 2 inch bands of snow. We continued the Blizzard Warning for Knox and Stark counties until 1 pm and the Winter Weather Advisory from McLean, Logan, Menard and Cass counties nw until 1 pm where blowing and drifting snow possible, and near whiteout conditions especially in rural areas nw of the IL river. Temps to continue to slip during this morning with afternoon highs in the low to mid 20s central IL and upper 20s to lower 30s in southeast IL. Wind chills of zero to 5 below common over the IL river valley from I-55 nw during this morning. We also continued the wind advisory over CWA until 15Z/10 am with west to nw winds gusting 35-45 mph into mid morning and winds only slowly diminishing later this morning and afternoon, still gusting 30-35 mph by late afternoon.

The strong low pressure lifts into northern Quebec by sunrise Tue while strong mid/upper level trof shifts eastward into the central Great lakes and eastern Ohio river valley. A 1030 mb high pressure ridge moves over the southern plains/lower MS river valley and ridging northward over the MS river valley by Tue morning. This to help decrease the winds further during tonight with some decreasing of low clouds overnight/Tue morning. Very cold lows tonight of 5-10F from I-55 nw and 10-15F over east central and se IL. Wind chills to lower to zero to 10 below during tonight into mid Tue morning from I-70 north and zero to 5 above in far southeast IL for minimum wind chills.

Fair weather expected Tue over central/se IL as surface ridge shifts eastward over IL during Tue morning and into the Ohio river valley by late Tue afternoon. Still subfreezing highs Tue of 25-32F, mildest in southeast IL and from Springfield sw. WNW winds are much lighter on Tue morning with gusts 15-20 mph and turn south to sw during Tue afternoon as ridge shifts east of central IL. A northern stream clipper system dives se from the Canadian Rockies and weakens somewhat as it moves into IL/IN during Tue night. This will likely bring a period of light snow to the area with most areas seeing less than 1 inch, except around 1 inch from I-74 north. Lows Tue night in the low to mid 20s.

Dry weather return on Wed as weakening clipper system moves away from IL Wed morning and skies become partly to mostly sunny Wed afternoon. SW winds and more sunshine to warm temps into the upper 40s to around 50F northern/ne CWA and mid to upper 50s southeast IL and from Springfield sw. Even warmer low to mid 60s over MS river valley over sw IL/near St Louis where warm front is near.

Another clipper system passes by north and ne of central IL during Wed night into Thu morning with its pcpn chances staying out of CWA. Warmer highs in the upper 50s to around 60F northern CWA and low to mid 60s central and southern CWA, with upper 60s and lower 70s over sw IL. A strong 595 dm 500 mb high over southern CA and AZ to try and build heights over IL late this week with IL in a WNW upper level flow of Pacific air mass. Mild highs in the mid 60s to lower 70s Fri and 70-75F on Saturday, cooling a bit into the 60s on Sunday as a cold front pushes through during Sat night. Could be low chances of light rain showers Sat night into Sunday morning. Temps cool closer to normal next Monday with highs in the upper 40s/lower 50s.

07

AVIATION

(For the 06z TAFs through 06z Monday Night) Issued at 1248 AM CDT Mon Mar 16 2026

Snow with IFR and MVFR cigs, along with ranging vis from 9sm at SPI to 1 1/4sm at PIA. Snow will continue to overspread the area and this will bring IFR conditions at all sites during the overnight hours...due to snow. Conditions slowly improve toward morning as the snow tapers off to intermittent during the day and afternoon. MVFR cigs will continue through the evening with SPI and PIA becoming VFR toward midnight. Northwest winds will prevail through the period. Speeds will be quite strong overnight and into tomorrow morning, but then slow in the evening hours.

Auten

ILX WATCHES/WARNINGS/ADVISORIES

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

Blizzard Warning until 1 PM CDT this afternoon for ILZ027-028.

Winter Weather Advisory until 1 PM CDT this afternoon for ILZ029>031-036>038-040>042-047-048.