textproduct: Central Illinois

KEY MESSAGES

- There is a slight to elevated risk of severe storms from mid Sunday afternoon into mid Sunday evening. Damaging winds is greatest threat with 30-45% risk in southeast IL, followed next by tornadoes with 5% to less than 10% risk in southeast IL. There is also a 5% risk of large hail over the IL river valley. Areas along and east of I-55 having having a greater threat of stronger wind gusts 75 mph or higher and EF-2 or stronger tornadoes. - A sharp transition from rain to snow occurs late Sunday evening and overnight Sunday night behind a strong cold front with some snow accumulations and blowing snow especially from I-55 northwest. There could be wind gusts up to 45 mph or higher at times Sunday afternoon into Monday.

- Sub-freezing high temperatures and minimum wind chills between zero and 10 below zero for areas west of the IL river late Sunday night into Monday morning, and across central IL Monday night into mid Tuesday morning.

DISCUSSION

Issued at 330 AM CDT Sat Mar 14 2026

The 08Z/3 am surface map shows 999 mb low pressure north of Lake Ontario over southeast Ontario Province that brought the very windy conditions to central and northern IL yesterday has pulled away from the area with much lighter northerly winds 7-14 mph. Weak 1022 mb high pressure was over central MN and ridging se into central IL. A weak frontogenetic forcing/isentropic lift into central IL producing light echo returns on radar over central IL into northern MO and much of Iowa. Though this is mostly virga over central IL so far due to dry low levels (10-15F temp/td spread) with mid level cloud bases around 10k ft over central IL, with mostly clear skies in southern/se IL. Temps were in the mid 30s from Macomb to Bloomington north, upper 30s heart of central IL and lower 40s from I-70 south.

The latest CAMs continue showing a narrow band of light precipitation (mainly light snow or flurries) lifting north of I-74 by late morning while weakening. May just be flurries with this band due to dry low levels and weak lift. Will see some decrease in cloud cover especially this afternoon south of I-74, with partly to mostly cloudy skies overall today but more sunshine in southeast IL and sw CWA where milder highs in the mid to upper 50s. Highs around 50F from I-74 north where more clouds prevail much of today. Winds become east to SE and increase a bit during the day with gusts 18-25 mph by afternoon.

Forecast models have trended slower with arrival of precipitation tonight with much of CWA dry tonight despite warm front lifting northward over CWA during overnight as ~990 mb low pressure ejects eastward from WY into sw Iowa by sunrise Sunday, with best forcing north and nw over Iowa and WI. This potent storm system to deep its low pressure as it tracks across northern IL Sunday afternoon reaching near Chicago by sunset Sunday. Strong southerly winds to increase during Sunday with gusts 35-50 mph by Sunday afternoon. HREF has 30-60% chance of over 50 mph wind gusts east of the IL river and north of I-70 Sunday afternoon and early Sunday evening. The REFS has 25-50% chance of wind gusts of 55 mph or higher over east central IL from during early to mid Sunday afternoon. We will likely need a high end wind advisory Sunday afternoon into Sunday night, and possibly into Monday.

A strong cold front to push into west central IL early Sunday afternoon, and reach the IL/IN border by early Sunday evening. This will likely bring showers and thunderstorms eastward across CWA during Sunday. Warmer highs in the mid to upper 60s Sunday with areas se of I-70 around 70F. Per SPC Day2 outlook... While instability is likely to be a limiting factor Sunday afternoon and early evening, strong large- scale ascent coupled with developing extreme shear profiles will likely result in corridors of damaging winds, with a few tornadoes as well. Shallow convection is likely to develop along the cold front over MO by early afternoon, with gradual strengthening as the air mass destabilizes. Storms are also expected to develop ahead of the cold front late in the day and into the evening over southern IL into southeast MO, with increasing wind and tornado risk for eastern/se IL into IN. SPC day2 continued slight risk of severe storms over much of CWA from Quincy to Galesburg southeast, with enhanced risk se of a Danville to Shelbyville line. There is a 30-45% risk of damaging winds in southeast IL and hatched area for wind gusts of 75 mph or higher from I-55 east. There is also a hatched area for EF2 or stronger tornadoes from I-55 east (for QLCS tornadoes along possible squall line).

Then there is the winter side of this potent storm system as much colder air arrives on west to nw winds gusting 35-50 mph behind the cold front. The rain to turn to snow over the IL river valley late Sunday evening and over rest of CWA during overnight Sunday night. Could see 2-4 inches of snow over the IL river valley, highest over Knox and Stark counties and will likely see blowing snow develop by overnight Sunday night into Monday. Between 1-2 inches over heart of central IL and less than 1 inch of snow in southeast IL. Will likely need a winter weather advisory for areas from I-55 nw and areas further nw may be having near white out conditions at times. Much colder air ushers in during Sunday night behind cold front with wind chills of zero to 5 below over the IL river valley late Sunday night into Monday morning. Windy and snowy conditions continue Monday, though snow to be diminishing from sw to ne especially Monday afternoon as strong low pressure 980-985 mb lift s ne of eastern upper MI peninsula. Highs Monday only in the low to mid 20s over central IL and upper 20s to near 30F in southeast IL. Very cold Monday night with lows in the single digits west of I-57 and lower teens in eastern IL. Much of central IL to see wind chills down to zero to 10 below Monday night into mid Tue morning with even southeast IL near zero wind chills. Some flurries possible ne CWA Monday evening, otherwise dry Monday night and Tue. Cold yet on Tue with highs 27-32F, coldest ne CWA.

Another quick moving clipper system to dive down from the northern Canadian Prairie Provinces into WI/IL overnight Tue night and bring good chance of light snow Tue night, though accumulations look minor. Lows Tue night in the low to mid 20s.

A pattern chance to occur during 2nd half the week as strong upper level ridge over the desert southwest builds closer to IL while strong mid/upper level trof pulls away from the Midwest. Highs Wed moderate into the 50s (near 60F from Jacksonville sw to MS river valley) and into the low to mid 60s Thu through Saturday with upper 60s to near 70F near west central/sw IL by MS river valley. ECMWF shows a northern stream clipper system passing by north of central IL Wed night into Thu morning and we kept a dry forecast going from Wed through Saturday.

The Climate Prediction Center (CPC) 8-14 Day outlook for Mar 21-27th has 50-60% chance of above normal temperatures over central/se IL and 35-40% chance of below normal precipitation.

07

AVIATION

(For the 18z TAFs through 18z Sunday Afternoon) Issued at 1250 PM CDT Sat Mar 14 2026

A deepening low pressure system approaching from the west will result in breezy conditions beginning tonight. East-southeast winds will veer to the south Sunday morning with gusts becoming strong later in the morning. Periods of showers and storms are possible (~30% chance) as early as Sunday morning with the threat for strong to severe storms holding off until later in the day, after 18Z. VFR conditions are likely through most of the TAF period, with medium to high probabilities for ceilings to fall below 3k ft in west-central Illinois after 15Z.

NMA

ILX WATCHES/WARNINGS/ADVISORIES

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