textproduct: Central Illinois

KEY MESSAGES

- Breezy west to northwest winds gusting 20 to 30 mph along with a few lingering bands of light snow showers and scattered flurries early this morning. This may cause patchy blowing snow and some travel impacts especially in open rural areas.

- Cold wind chills in the single digits below zero over central IL from I-70 north into mid morning. Today will likely be the coldest St Patrick's Day since 1941 over much of the area.

- A fast-moving clipper system will bring a period of light snow to central and southeast IL tonight. Up to around 1 inch of snow is expected over much of central IL, with a dusting to half inch in southeast IL. Up to around 2 inches of snow possible northwest of the IL river. - Spring-like warmth returns late this week. Temperatures will climb into the 60s on Thursday, with upper 60s and lower 70s Friday and 70s on Saturday.

DISCUSSION

Issued at 345 AM CDT Tue Mar 17 2026

IDOT Winter Weather Road conditions shows some snow/ice covered roadways from Fulton, Tazewell, McLean and Ford/Iroquois counties northward early this morning. On major interstates google maps shows some lingering "slow ups" on I-74 north of Galesburg (this was closed earlier tonight) and on I-39 between Minonk and Wenona. Still getting breezy west/nw winds gusting 20-30 mph and a few lingering bands of light snow showers from IL river east though with diminishing trends past few hours. Issued a Special Weather Statement (SPS) from Fulton to McLean counties northward until daybreak advising caution if traveling due to patchy shallow blowing snow and possible snow/ice covered stretches.

The 08Z/3 am surface map shows a powerful 972 mb low pressure in southeast Quebec, nw of the St Lawrence Seaway, with its cyclonic circulation as far sw WI, IL and KY. A 1028 mb high pressure over east Texas and ridging northward into western parts of IA/MN. Aloft a very strong mid/upper level trof was over the central Great Lakes and Ohio river valley, including IL/IN. A narrow band of snow showers was sw of Chicago metro and tracking se and this should stay ne of CWA early this morning. A few other weaker/narrow bands of light snow showers were south of I-72 into southeast IL while more widespread snow showers were over southern IN and far se IL, also moving se. As short wave trof shifts east of IL between 12-14Z, expect these light snow shower bands to continue to diminish and shift east/se of CWA. Nighttime Microphysics RGB satellite loop shows clearing of low clouds over nw and sw IL while large breaks in the low clouds from Rushville to Springfield to Paris south. Models shows low clouds continue to decrease from the west during this morning as WNW to NW winds also decrease as high pressure ridge shifts east over IL by early afternoon. But mid/high clouds to quickly spread eastward across IL during this afternoon ahead of approaching clipper system. Subfreezing highs again over CWA in the 25-32F range (highest in southeast IL and from Jacksonville sw. This will likely be the coldest St Patrick's Day since 1941 and likely rank in the top 2-4th place for coldest daytime highs on Mar 17th for Peoria, Springfield, Lincoln, Champaign/Urbana and Bloomington/Normal.

A northern stream short wave over western Canadian Prairies to race se into the upper MS river valley by midnight, likely spread light snow into the IL river valley early this evening and over rest of CWA during mid/late evening. The light snow to diminish from the west later tonight with low chances of light snow/flurries in eastern IL Wed morning especially early. Mixed pcpn or light rain should stay sw of CWA tonight with our CWA staying mostly light snow. Up to around 1 inch of snow expected over much of central IL, with a dusting to half inch in southeast IL and 1.5-2 inches possible nw of the IL river. The southern edge of this system weakens so areas further south/se should be lighter snow amounts. Lows tonight in the low to mid 20s central IL and upper 20s south of I-70.

Another clipper system passing to our north/ne late Wed night and Thu morning could bring low chances of light rain showers especially ne CWA. Otherwise fairly dry conditions expected late this week.

A nice warming trend expected Wed through Saturday as upper level heights rise over IL with building upper level ridge over the Southwest States. Highs Wed in the upper 40s to around 50F from I-74 north and mid to upper 50s in southeast IL and from Springfield sw with lower 60s near the MS river valley of sw IL. Highs Thu in the low to mid 60s, with upper 60s from Springfield sw with lower to mid 70s near the MS river valley/sw IL. Highs in the upper 60s/lower 70s Friday and in the 70s Saturday, with Ecmwf trending the warmest with mid to upper 70s in ne CWA and lower 80s se CWA and 85F at Springfield on Sat.

Models differ on timing of a cold front dropping southward over IL during either Saturday night (ECMWF) or Sunday (GFS/GEM). The Ecmwf is more aggressive with rain on Sunday behind the front while GFS and GEM are dry. Models agree on tighter pressure gradient and giving stronger winds on Sunday along with cooler temps especially by Sunday night and Monday.

The Climate Prediction Center (CPC) 8-14 Day Outlook for Mar 24-30th has 35-40% chance of above normal temperatures over central and southeast IL, and trending near normal for precipitation.

07

AVIATION

(For the 12z TAFs through 12z Wednesday Morning) Issued at 631 AM CDT Tue Mar 17 2026

VFR conditions will prevail at all TAF sites today, but then become MVFR as the next round of light snow moves across the TAFs this evening and overnight. Cig will drop to around 2.5kft and vis will drop to 3-4sm with light snow at all sites. Snow will taper off late tonight after about 8-10z, but did not add at this time to keep TAF size down. Winds will be light for most of the period but then increase after midnight with gusts reaching 20kts of higher. Direction will go from northwest to west to south through the period.

Auten

ILX WATCHES/WARNINGS/ADVISORIES

None.