947
FXUS63 KILX 211728
AFDILX
AREA FORECAST DISCUSSION...UPDATED AVIATION
NATIONAL WEATHER SERVICE LINCOLN IL
1128 AM CST WED JAN 21 2026
KEY MESSAGES
- A DISTURBANCE THIS EVENING MAY BRING A FEW FLURRIES, BUT
ACCUMULATIONS ARE UNLIKELY, ONLY AROUND 20-30 PERCENT
ALONG/NORTH OF I-74.
- AN ARCTIC AIR MASS WILL BRING A RETURN OF BITTERLY COLD
TEMPERATURES THURSDAY NIGHT THROUGH THE WEEKEND. WIND CHILL VALUES
AS COLD AS 10 TO 30 BELOW ARE EXPECTED FRIDAY MORNING. AN
EXTREME COLD WATCH IS IN EFFECT FOR A HAVANA TO BLOOMINGTON LINE
NORTH.
- A WINTER STORM SYSTEM WILL PASS THROUGH THE SOUTHERN STATES
FRIDAY THROUGH THE WEEKEND, AND COULD SPREAD SNOW INTO PARTS OF
CENTRAL AND SOUTHEAST IL. THERE IS AROUND A 70 PERCENT CHANCE
OF EXCEEDING AN INCH OF SNOW SOUTH OF I-70 AND A 40 PERCENT
CHANCE OF EXCEEDING 4 INCHES.
DISCUSSION
ISSUED AT 203 AM CST WED JAN 21 2026
LONG TERM (TODAY THROUGH TONIGHT):
A WEAK SURFACE LOW, ASSOCIATED WITH A FAST-MOVING CLIPPER SYSTEM,
IS CURRENTLY TRACKING ACROSS NORTHWESTERN ILLINOIS CENTERED NEAR
DVN AT 08Z, WITH AN ATTENDANT COLD FRONT EXTENDING SOUTHWESTWARD
ACROSS NORTHEAST MISSOURI. A LOW-LEVEL JET PRECEDING THIS FEATURE
IS PRODUCING LIGHT SNOW INTO PORTIONS OF NORTHERN ILLINOIS THIS
MORNING. WHILE SOME WEAK RADAR RETURNS ARE NOTED FURTHER SOUTH
INTO CENTRAL ILLINOIS, OBSERVATIONS SUGGEST LITTLE, IF ANY,
PRECIPITATION IS REACHING THE SURFACE (VIRGA). BREEZY SOUTHWEST
WINDS AHEAD OF THE FRONT WILL PERSIST THROUGH THE MORNING HOURS
BEFORE SHIFTING TO THE WEST AND REMAINING GUSTY THROUGH SUNSET
FOLLOWING FRONTAL PASSAGE. MODEL GUIDANCE SUGGESTS PEAK GUSTS
RANGING FROM 30 TO 45 MPH FOR MOST AREAS, WITH POTENTIAL GUSTS
NEARING 50 MPH NORTH OF THE ILLINOIS RIVER. HOWEVER, GIVEN ONLY A
20-40 PERCENT CHANCE OF EXCEEDING WIND ADVISORY CRITERIA (45 MPH)
IN THESE NORTHERN AREAS, CONFIDENCE REMAINS TOO LOW FOR ISSUANCE
AT THIS TIME.
ANOTHER CLIPPER SYSTEM IS POISED TO CROSS CENTRAL ILLINOIS LATE
THIS EVENING. SURFACE WINDS WILL BRIEFLY BACK TO THE SOUTHWEST
THIS EVENING BEFORE VEERING TO THE NORTHWEST OVERNIGHT AS THE
NEXT WAVE TRAVERSES THE REGION. SIMILAR TO THE FIRST SYSTEM, THE
MAIN SNOW SHIELD IS FORECAST TO REMAIN NORTH OF OUR CWA. ONLY
SMALL CHANCES (AROUND 30%) FOR LIGHT SNOW EXTEND DOWN INTO THE
I-74 CORRIDOR. DUE TO DRY LOW LEVELS, ANY OBSERVED PRECIPITATION
IS EXPECTED TO PRIMARILY BE VIRGA OR FLURRIES, RESULTING IN LITTLE
TO NO ACCUMULATION ACROSS THE FORECAST AREA.
LONG TERM (THURSDAY THROUGH EARLY NEXT WEEK):
THE DOMINANT FEATURE IN THE LONG-TERM FORECAST IS THE ARRIVAL OF
A BITTERLY COLD AIRMASS. A VERY STRONG SURFACE HIGH-PRESSURE
SYSTEM (1050+ MB) WILL BUILD FROM THE CANADIAN ROCKIES INTO THE
CENTRAL AND NORTHERN GREAT PLAINS THURSDAY NIGHT INTO FRIDAY. THIS
HIGH WILL USHER IN AN ARCTIC AIRMASS, WITH AIR TEMPERATURES
EXPECTED TO DIP BELOW ZERO IN PARTS OF THE FORECAST AREA BY FRIDAY
MORNING. PROBABILITIES FOR SUB-ZERO TEMPERATURES RUN HIGH
(50-80%) NORTH OF I-72. MORE WIDESPREAD SUB-ZERO TEMPERATURES ARE
LIKELY BY SATURDAY MORNING, WITH THOSE SAME PROBABILITIES (50-80%)
EXTENDING SOUTH TO THE I-70 CORRIDOR. DESPITE SLIGHTLY COLDER AIR
TEMPERATURES ON SATURDAY MORNING, WIND CHILL VALUES ARE EXPECTED
TO BOTTOM OUT FRIDAY MORNING. HIGH CONFIDENCE (LREF PROBABILITY
60-80%) EXISTS FOR WIND CHILLS TO DROP BELOW -25°F NORTH OF A
HAVANA TO BLOOMINGTON LINE, WHICH NECESSITATES THE ISSUANCE OF AN
EXTREME COLD WATCH FOR THIS AREA.
CONCURRENTLY, ATTENTION SHIFTS SOUTH TO A DEVELOPING BAROCLINIC
ZONE ACROSS THE SOUTHERN U.S. A BROAD CORRIDOR OF STRONG
ISENTROPIC ASCENT, SPANNING FROM TEXAS TO GEORGIA, WILL ALLOW
AMPLE GULF MOISTURE TO OVERRUN THE ARCTIC AIRMASS SETTLED OVER
PORTIONS OF THE MID-MISSISSIPPI AND TENNESSEE VALLEYS, GENERATING
A MIX OF SNOW AND FREEZING RAIN. INITIALLY, THIS PRECIPITATION
WILL BE WELL SOUTH OF THE LOCAL FORECAST AREA. HOWEVER, AS THE
SURFACE RIDGE RETREATS NORTHEAST TOWARD THE GREAT LAKES LATE IN
THE WEEKEND, THERE IS AN INCREASING RISK THAT PRECIPITATION MAY
SPREAD NORTH INTO CENTRAL ILLINOIS, POTENTIALLY YIELDING
ACCUMULATING SNOW. UNCERTAINTY REMAINS REGARDING THE NORTHERN
EXTENT OF THIS SNOW SHIELD. HOWEVER, RECENT MODEL TRENDS,
PARTICULARLY THE 21.00Z GFS ALIGNING CLOSER WITH THE ECMWF,
SUGGEST A BETTER CHANCE FOR ACCUMULATING SNOW ACROSS AT LEAST
PORTIONS OF CENTRAL ILLINOIS LATER SATURDAY INTO SUNDAY. THE NBM
24-HOUR PROBABILITY FOR 1 INCH OF SNOW HAS INCREASED, NOW SHOWING
A 20% CHANCE UP TO THE GALESBURG AREA AND A HIGHER 70% CHANCE
SOUTH OF THE I-70 CORRIDOR. AREAS SOUTH OF I-70 ALSO NOW HOLD A
40% CHANCE FOR AT LEAST 4 INCHES OF SNOW ACCUMULATION. WE WILL
CONTINUE TO CLOSELY MONITOR THE EVOLUTION OF THIS SYSTEM.
DEUBELBEISS
AVIATION
(FOR THE 18Z TAFS THROUGH 18Z THURSDAY AFTERNOON)
ISSUED AT 1128 AM CST WED JAN 21 2026
PRIMARILY VFR CONDITIONS ARE EXPECTED THROUGH THE UPCOMING 24
HOURS, HOWEVER A WEAK DISTURBANCE PASSING BY MAINLY TO THE NORTH
COULD BRING A BRIEF SNOW SHOWER THIS EVENING TO KPIA AND KBMI, AND
HAVE INCLUDED PROB30 FOR 5SM VSBY IN -SN BETWEEN 00Z AND 03Z. WNW
WINDS 40-45 KTS AT 2000 FT AGL COULD PROVIDE A BRIEF PERIOD OF
WIND SUBSTANTIAL WIND SHEAR THIS EVENING, MAINLY FOR KDEC AND
KCMI, BUT HAVE NOT INCLUDED IN TAFS YET DUE TO THE BRIEF/MARGINAL
CHARACTER. WINDS W 12-18 KTS WITH GUSTS 20-25 KTS THIS AFTERNOON,
DECREASING SLIGHTLY AND SHIFTING SW LATE THIS AFTERNOON INTO
EVENING, THEN INCREASING AND BECOMING WNW BEHIND THE EVENING
DISTURBANCE, WITH GUSTS 25-35 KTS OVERNIGHT. WINDS DECREASING
AGAIN LATE IN THE NIGHT.
37
ILX WATCHES/WARNINGS/ADVISORIES
EXTREME COLD WATCH FROM LATE THURSDAY NIGHT THROUGH FRIDAY
MORNING FOR ILZ027>031-036>038.
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