122
FXUS63 KILX 201120
AFDILX
AREA FORECAST DISCUSSION...UPDATED AVIATION
NATIONAL WEATHER SERVICE LINCOLN IL
520 AM CST TUE JAN 20 2026
KEY MESSAGES
- A PAIR OF CLIPPER SYSTEM WILL SKIRT JUST TO OUR NORTH TONIGHT
AND AGAIN WEDNESDAY EVENING. GUSTY WINDS ARE EXPECTED AT TIMES
BUT LITTLE IF ANY PRECIP IS EXPECTED. THE GREATEST POTENTIAL
FOR ANY ACCUMULATING SNOW IS 20-40 PERCENT TUESDAY EVENING
NEAR/NORTH OF I-74.
- AN ARCTIC AIR MASS WILL BRING A RETURN OF BITTERLY COLD
TEMPERATURES THURSDAY NIGHT THROUGH THE WEEKEND. SINGLE DIGIT
HIGHS AND SUB-ZERO LOWS WILL BE POSSIBLE FOR PORTIONS OF
CENTRAL ILLINOIS.
DISCUSSION
ISSUED AT 147 AM CST TUE JAN 20 2026
THIS MORNING, AN EXPANSIVE SURFACE RIDGE IS IN PLACE CENTERED
OVER THE MID MISSISSIPPI VALLEY AND SPANNING MUCH OF THE MIDDLE
SECTION OF THE COUNTRY. ALOFT, A BROAD UPPER TROUGH CENTERED OVER
HUDSON BAY CONTINUES TO DRIVE NORTHWEST FLOW ACROSS THE MIDWEST
WITH A SERIES OF LOW AMPLITUDE SHORTWAVES BRINGING OCCASIONAL
PRECIP CHANCES TO THE GREAT LAKES AND PORTIONS OF THE MIDWEST.
RATHER BENIGN WEATHER CONDITIONS ARE EXPECTED TODAY UNDER THE
INFLUENCE OF THE SURFACE RIDGE, WHICH SLOWLY SHIFTS TO OUR EAST
THIS MORNING, ALLOWING FOR RETURN FLOW TO OVERSPREAD CENTRAL
ILLINOIS. THIS RETURN FLOW WILL HELP TEMPERATURES REBOUND FROM THE
BITTER COLD, WITH HIGHS REACHING THE UPPER 20S TO LOWER 30S THIS
AFTERNOON. MEANWHILE, A CLIPPER SYSTEM CURRENTLY OVER SOUTHERN
BC/ALBERTA WILL TRACK ACROSS IOWA LATE THIS EVENING, THEN NORTHERN
ILLINOIS OVERNIGHT. LATEST RUNS OF THE GEM, ECMWF, AND NAM ALL
SUGGEST THAT SNOW WITH THIS WAVE WILL REACH AS FAR SOUTH AS THE
I-74 CORRIDOR, WHILE THE GFS KEEPS IT JUST TO OUR NORTH. NBM
PROBABILITIES FOR ACCUMULATING SNOW (>0.1 IN) ARE CONFINED TO
AREAS NORTH OF A GALESBURG TO PEORIA TO EL PASO LINE (10%
CONTOUR), PEAKING AROUND 20-40 PERCENT ACROSS OUR NORTHERN TIER OF
COUNTIES (KNOX/STARK/MARSHALL). NAM FORECAST SOUNDINGS AT LACON,
IL, SHOW THE LOW LEVELS STRUGGLING TO SATURATE UNTIL AROUND 12Z
WEDNESDAY, THEN QUICKLY DRYING OUT IN THE MID-LEVELS BY 13Z,
COINCIDING WITH THE PASSAGE OF THE MAIN H5 VORT MAX AND SUBSEQUENT
LOSS OF FORCING. FURTHERMORE, A HANDFUL OF THE CAMS DO SHOW SOME
LIGHT PRECIPITATION ON A TRAILING SURFACE COLD FRONT, WHICH IS NOT
ADVERTISED BY THE REGIONAL/GLOBAL MODELS. ACCOMPANYING FORECAST
SOUNDINGS INDICATE SOME DRY AIR BELOW 700MB THAT WILL BE DIFFICULT
TO OVERCOME GIVEN THE SHORT DURATION OF FORCING, BUT WE CANNOT
ENTIRELY RULE OUT SOME VERY LIGHT SNOW OR FLURRIES CONTINUING
LATER INTO THE OVERNIGHT AND EARLY MORNING HOURS WEDNESDAY.
ANOTHER SHORTWAVE TROUGH TAKES AIM AT THE GREAT LAKES WEDNESDAY
EVENING. PRECIPITATION CHANCES WITH THIS SYSTEM ARE EXPECTED TO
REMAIN WELL TO OUR NORTH; HOWEVER, WE LOCALLY ANTICIPATE THE
WARMING TREND TO CONTINUE AS SOUTHWEST FLOW OUT AHEAD OF THE WAVE
HELPS PUSH TEMPERATURES INTO THE MID 30S TO MID 40S ACROSS CENTRAL
ILLINOIS. DESPITE THE LOW POPS, CENTRAL ILLINOIS WILL STILL FEEL
THE EFFECTS OF THIS SYSTEM AS GUSTY WINDS DEVELOP. THE NBM
INDICATES AN 80 TO GREATER THAN 90 PERCENT CHANCE OF EXCEEDING 30
MPH WIND GUSTS WEDNESDAY, WITH PROBABILITIES GENERALLY 20-60
PERCENT (HIGHEST OVER EAST-CENTRAL IL) OF EXCEEDING 40 MPH GUSTS.
A VERY STRONG 1050MB SURFACE HIGH WILL BUILD FROM THE CANADIAN
ROCKIES INTO THE CENTRAL AND NORTHERN GREAT PLAINS THURSDAY NIGHT
INTO FRIDAY. A BITTERLY COLD AIR MASS ASSOCIATED WITH THIS STRONG
HIGH WILL OVERSPREAD CENTRAL ILLINOIS STARTING THURSDAY NIGHT,
WITH AIR TEMPERATURES DIPPING BELOW ZERO IN SPOTS BY FRIDAY
MORNING. WIDESPREAD SUB-ZERO TEMPERATURES ARE POSSIBLE BY SATURDAY
MORNING (60 PERCENT PROBABILITY ALONG/NORTH OF I-72 PER NBM),
WHICH WILL CONTRIBUTE TO WIND CHILL VALUES RANGING FROM 10 BELOW
IN THE SOUTH TO AROUND 25 BELOW IN THE NORTH. MEANWHILE, A WINTRY
MIX OF SNOW AND FREEZING RAIN WILL OCCUR WELL TO OUR SOUTH FRIDAY
ALONG THE BAROCLINIC ZONE OVER PORTIONS OF THE DEEP SOUTH. AS THE
SURFACE RIDGE RETREATS NORTHEAST ACROSS THE GREAT LAKES LATE THIS
WEEKEND, PRECIPITATION MAY BE ABLE TO SPREAD NORTH ACROSS CENTRAL
ILLINOIS, POTENTIALLY PRODUCING ACCUMULATING SNOW. THERE REMAINS
QUITE A BIT OF UNCERTAINTY ON HOW FAR NORTH THIS SNOW WILL OCCUR.
THE LATEST RUN OF THE GFS KEEPS CENTRAL ILLINOIS DRY THROUGH THE
WEEKEND, WHILE THE CANADIAN AND EUROPEAN DETERMINISTIC RUNS DO
BRING SNOW ACCUMULATIONS INTO CENTRAL ILLINOIS. THE NBM 24-HOUR
PROBABILITY FOR AN INCH OF SNOW REMAINS LOW, ONLY AROUND 20%
AROUND THE I-70 CORRIDOR AND AROUND 10% ALONG THE I-74 CORRIDOR.
THIS PERIOD WILL REQUIRE CLOSE MONITORING AS THE EVENT DRAWS
NEARER.
DEUBELBEISS
AVIATION
(FOR THE 12Z TAFS THROUGH 12Z WEDNESDAY MORNING)
ISSUED AT 519 AM CST TUE JAN 20 2026
LIGHT SW WINDS AND VFR CONDITIONS ARE IN PLACE THIS MORNING UNDER
THE INFLUENCE OF HIGH PRESSURE OVER THE MID MISSISSIPPI VALLEY.
AS THE RIDGE SHIFT EAST, SSW WINDS WILL PICK UP ABOVE 10 KT AROUND
MIDDAY TODAY. WINDS WILL FURTHER PICK UP LATE THIS EVENING AND
OVERNIGHT AHEAD OF AN APPROACHING LOW THAT TRACKS ACROSS NORTHERN
ILLINOIS LATE TONIGHT. EXPECT INCREASING MID CLOUDS WITH MVFR
CEILINGS AND SNOW EXPECTED TO STAY JUST NORTH OF THE TERMINALS,
BUT NOT FAR FROM SPI/BMI. A LOW LEVEL JET AHEAD OF THE LOW TRACK
WILL ALSO RESULT IN LOW LEVEL WIND SHEAR WITH WINDS AROUND 020
PEAKING BETWEEN 50-55KT OVERNIGHT.
DEUBELBEISS
ILX WATCHES/WARNINGS/ADVISORIES
NONE.
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