509
FXUS63 KILX 221121
AFDILX
AREA FORECAST DISCUSSION...UPDATED AVIATION
NATIONAL WEATHER SERVICE LINCOLN IL
521 AM CST THU JAN 22 2026
KEY MESSAGES
- AN ARCTIC AIR MASS WILL BRING BITTERLY COLD TEMPERATURES TO
CENTRAL ILLINOIS STARTING TONIGHT. WIND CHILL VALUES AS COLD AS
10 TO 30 BELOW ARE EXPECTED FRIDAY MORNING. AN EXTREME COLD
WARNING IS IN EFFECT FOR A HAVANA TO BLOOMINGTON LINE NORTH WITH
COLD WEATHER ADVISORIES IN EFFECT SOUTH TO THE I-70 CORRIDOR.
- A SIGNIFICANT WINTER STORM SYSTEM WILL PASS THROUGH THE SOUTHERN
STATES FRIDAY THROUGH THE WEEKEND, AND WILL LIKELY SPREAD SNOW
INTO PORTIONS OF CENTRAL AND SOUTHEAST IL. AREAS FROM AROUND
I-70 SOUTHWARD COULD SEE HEAVY SNOW WITH A 50% CHANCE OF
EXCEEDING 5 INCHES. A WINTER STORM WATCH IS IN EFFECT SATURDAY
MORNING THROUGH SUNDAY MORNING ALONG AND SOUTH OF I-70.
DISCUSSION
ISSUED AT 241 AM CST THU JAN 22 2026
A FORMIDABLE ARCTIC AIR MASS IS CURRENTLY PUSHING SOUTH INTO THE
UPPER MIDWEST AND WILL ENCOMPASS THE ENTIRETY OF CENTRAL ILLINOIS
TODAY AND TONIGHT. THE DRIVER IS A VERY STRONG 1050MB HIGH
PRESSURE SYSTEM ANALYZED OVER THE NORTHWEST TERRITORIES, COUPLED
WITH A LOW OVER QUEBEC, CREATING A POTENT NORTHERLY GRADIENT.
AFTER HIGHS REACH AROUND THE FREEZING MARK TODAY, TEMPERATURES
WILL PLUMMET SIGNIFICANTLY TONIGHT. EXPECT SINGLE DIGITS NORTH OF
I-70, WITH SUB-ZERO READINGS FILTERING INTO AREAS NORTH OF I-72.
COLD AIR ADVECTION WILL FOSTER STEEP LOW-LEVEL LAPSE RATES, AND
WHEN COMBINED WITH THE TIGHT PRESSURE GRADIENT AND 4MB/3HR
PRESSURE RISES, WILL LEAD TO INCREASINGLY BREEZY CONDITIONS LATE
TONIGHT INTO FRIDAY MORNING. AS A RESULT, DANGEROUSLY COLD WIND
CHILLS ARE FORECAST ACROSS THE REGION. MINIMUM WIND CHILL VALUES
WILL RANGE FROM APPROXIMATELY -30DEGF NEAR GALESBURG TO -5DEGF
NEAR LAWRENCEVILLE. THE -20DEGF WIND CHILL CONTOUR IS EXPECTED TO
FALL ALONG THE I-72/DANVILLE CORRIDOR, WITH THE -10DEGF CONTOUR
GENERALLY ALONG THE I-70 CORRIDOR. AN EXTREME COLD WARNING WILL
REPLACE THE CURRENT WATCH, AND COLD WEATHER ADVISORIES WILL BE
ISSUED FOR THE REMAINDER OF CENTRAL ILLINOIS NORTH OF I-70.
ATTENTION SHIFTS SOUTHWARD FRIDAY AS THE ARCTIC AIR MASS BEGINS
TO INTERACT WITH AMPLE GULF MOISTURE. THIS SETUP IS PROGGED TO
GENERATE A BROAD AND DEEP CORRIDOR OF ISENTROPIC ASCENT, INITIALLY
ACROSS TEXAS ON FRIDAY, THEN PROPAGATING INTO THE TENNESSEE
VALLEY ON SATURDAY. THE RESULT WILL BE A SIGNIFICANT WINTER STORM
IMPACTING THE REGION.
A WINTRY MIX OF SNOW AND ICE IS EXPECTED INITIALLY WITH SNOW
EXPECTED ON THE NORTHERN PERIPHERY OF THE SYSTEM. UNCERTAINTY
REMAINS ON THE EXACT NORTHERN EXTENT, BUT RECENT MODEL TRENDS HAVE
MADE A NOTABLE NORTHWARD SHIFT. THE KEY DIFFERENCE IN THE LATEST
GUIDANCE IS THE DEVELOPMENT OF A MORE ROBUST SURFACE LOW ALONG THE
BAROCLINIC ZONE, WHICH IS FORECAST TO TRACK NORTHEAST INTO THE
UPPER OHIO VALLEY BY THE END OF THE WEEKEND. THIS TRACK SHIFT
BRINGS THE HEAVIER SNOW FURTHER NORTH, AND SNOW ACCUMULATIONS ARE
APPEARING INCREASINGLY LIKELY ACROSS AT LEAST PORTIONS OF CENTRAL
AND SOUTHEAST ILLINOIS THIS WEEKEND.
THE NBM MEAN SNOWFALL HAS INCREASED MARKEDLY IN THE LATEST RUNS,
NOW SUGGESTING 6 TO 7 INCHES OF SNOW WILL BE POSSIBLE SOUTH OF
I-70, WITH AROUND 2 INCHES EXTENDING AS FAR NORTH AS GALESBURG.
HOWEVER, THE FORECAST CONFIDENCE REMAINS LOW, AS HIGHLIGHTED BY
THE NBM 48-HOUR SNOWFALL 25TH TO 75TH PERCENTILE SPREAD: AREAS
SOUTH OF I-70 SHOW A CONSIDERABLE RANGE FROM 2 INCHES (25TH
PERCENTILE) UP TO 11 INCHES (75TH PERCENTILE). FACTORS SUPPORTING
THE HIGHER-END SNOW TOTALS INCLUDE THE ANTECEDENT FRIGID AIR
MASS, WHICH WILL SUSTAIN A VERY DEEP (GREATER THAN 10KFT)
DENDRITIC GROWTH ZONE AT TIMES, SUPPORTING SNOW-TO-LIQUID RATIOS
(SLR) EXCEEDING 15:1. FURTHERMORE, THE GFS SHOWS A CORRIDOR OF
STRONG MID-LEVEL FRONTOGENESIS MOVING ACROSS THE AREA SUNDAY,
COUPLED WITH STEEP LAPSE RATES ATOP THE STRONGEST FORCING, WHICH
SUGGESTS THE POTENTIAL FOR A DEEP VERTICAL RESPONSE AND MESOSCALE
BANDING, A SCENARIO THAT COULD LEAD TO LOCALIZED, ENHANCED
SNOWFALL RATES.
MODEL TIMING DIFFERENCES ARE CURRENTLY WASHING OUT SOME FINER
DETAILS IN THE BLENDED FORECAST. WE WILL BE CLOSELY MONITORING
THE EVOLUTION OF THESE FEATURES OVER THE NEXT 24 TO 48 HOURS AS
MODELS HOPEFULLY CONVERGE ON A MORE UNIFIED SOLUTION. RESIDENTS
SHOULD PREPARE FOR SIGNIFICANT TRAVEL IMPACTS AND WINTER STORM
CONDITIONS THIS WEEKEND. A WINTER STORM WATCH REMAINS IN EFFECT
FOR AREAS SOUTH OF I-70.
DEUBELBEISS
AVIATION
(FOR THE 12Z TAFS THROUGH 12Z FRIDAY MORNING)
ISSUED AT 519 AM CST THU JAN 22 2026
WEST WINDS AND VFR CONDITIONS WILL PREVAIL ACROSS CENTRAL ILLINOIS
TODAY. A MODEST BREEZE WILL PICK UP IN THE NORTH WITH THE I-74
CORRIDOR GUSTING TO AROUND 20 KT MUCH OF THE AFTERNOON. WINDS WILL
TURN NW/NNW LATE THIS EVENING AND OVERNIGHT AS AN ARCTIC FRONT
PUSHES ACROSS THE REGION. GUSTS INTO THE LOW TO MID 20 KT RANGE
ARE EXPECTED BEHIND THE FRONT, BUT NO PRECIP IS EXPECTED.
DEUBELBEISS
ILX WATCHES/WARNINGS/ADVISORIES
EXTREME COLD WARNING FROM 3 AM TO NOON CST FRIDAY FOR ILZ027>031-
036>038.
COLD WEATHER ADVISORY FROM 3 AM FRIDAY TO NOON CST SATURDAY FOR
ILZ040>057-061>063.
WINTER STORM WATCH FROM SATURDAY MORNING THROUGH SUNDAY MORNING
FOR ILZ066>068-071>073.
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