936
FXUS63 KILX 211956
AFDILX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LINCOLN IL
156 PM CST TUE JAN 21 2025
KEY MESSAGES
- BITTERLY COLD TEMPERATURES CONTINUE INTO TONIGHT WITH WIND
CHILLS DIPPING TO 15 TO 20 BELOW. A COLD WEATHER ADVISORY IS IN
EFFECT AREA-WIDE OVERNIGHT INTO WEDNESDAY MORNING.
- TEMPERATURES WILL BEGIN TO MODERATE THROUGH THE SECOND HALF OF
THE WEEK WITH HIGHS BACK INTO THE 20S. A WEAK COLD FRONT WILL
BRING LESS THAN A HALF INCH OF SNOW TO PORTIONS OF CENTRAL
ILLINOIS WEDNESDAY NIGHT.
DISCUSSION
ISSUED AT 149 PM CST TUE JAN 21 2025
BITTER COLD CONTINUES...
THIS AFTERNOON, A COLD AIR MASS ASSOCIATED WITH A 1040MB RIDGE
ORIGINATING FROM THE ARCTIC A FEW DAYS AGO AND NOW EXTENDING FROM
TEXAS ACROSS ILLINOIS CONTINUES TO DRIVE WELL BELOW NORMAL
TEMPERATURES ACROSS CENTRAL ILLINOIS. TEMPS WILL TOP OUT ONLY IN
THE SINGLE DIGITS TODAY WITH A FEW SPOTS FALLING BACK BELOW ZERO
OVERNIGHT. SURFACE RIDGE AXIS WILL SHIFT TO OUR EAST OVERNIGHT
ALLOWING A SOUTHERLY BREEZE TO OVERSPREAD CENTRAL ILLINOIS AND
RESULTING IN NON-DIURNAL TEMPERATURE TRENDS WITH TEMPS STEADY OR
RISING SLIGHTLY OVERNIGHT. DESPITE THE RISING TEMPS, INCREASING
WINDS WILL STILL PRODUCE WIND CHILL VALUES OF 15 TO 20 BELOW
TONIGHT WITH ALL OF CENTRAL ILLINOIS NOW EXPECTED TO REACH THE
-15DEGF CRITERIA FOR COLD WEATHER ADVISORY.
TEMPERATURES MODERATING THROUGH THE SECOND HALF OF THE WEEK...
MID LEVEL WARM AIR ADVECTION BEHIND THE DEPARTING LOW LEVEL RIDGE
AND AHEAD OF AN APPROACHING UPPER TROUGH WILL BE IN PLACE THROUGH
AT LEAST THE FIRST HALF OF THE DAY WEDNESDAY AND WILL HELP
MODERATE TEMPS ACROSS THE REGION. LREF INDICATES PROBABILITY OF
HIGH TEMPS IN EXCESS OF 20 DEGREES GREATER THAN 90 PERCENT WEST OF
I-57, TAPERING OFF TO AROUND 50 PERCENT AT THE IL/IN STATE LINE.
PROBABILITY OF EXCEEDING 30 DEGREES HAS LOWERED FOR WEDNESDAY, NOW
ONLY ABOUT 15 PERCENT NEAR THE LOWER ILLINOIS RIVER. HAVE LOWERED
MAXT FOR WEDNESDAY AS A RESULT OF THESE TRENDS, BUT WILL STILL BE
A FAIRLY DRAMATIC CHANGE FROM TODAY.
AN UPPER LEVEL TROUGH WILL DIG ACROSS CENTRAL ILLINOIS WEDNESDAY
NIGHT INTO THURSDAY. THERE IS A CONSISTENT SIGNAL BETWEEN MODELS OF
DIMINISHING QPF AS THIS WAVE MOVES FROM IOWA INTO CENTRAL ILLINOIS,
BUT FORECAST SOUNDING STILL SHOW A BRIEF WINDOW OF SATURATION AND A
RELATIVELY DEEP DGZ THAT SHOULD ALLOW FOR SOME EFFICIENT SNOW
PRODUCTION DESPITE THE WEAKENING FORCING FOR ASCENT. LREF INDICATES
A 60-90% CHANCE (HIGHEST NORTH) OF AT LEAST A DUSTING (0.1 INCHES)
OF SNOW NORTH OF I-72 WITH PROBABILITIES TAPERING TO 10% BY THE I-70
CORRIDOR THROUGH THURSDAY MORNING. THE PROBABILITY FOR HALF AN INCH
OF SNOW DROPS OFF DRAMATICALLY TO ONLY 10 PERCENT NEAR THE I-74
CORRIDOR NORTHWEST OF BMI.
BEHIND THE WAVE, TEMPERATURES ARE PROGGED TO DIP BACK DOWN AGAIN
THURSDAY WITH HIGHS MAINLY IN THE 20S NORTH OF I-70 AND AREAWIDE ON
FRIDAY. THIS ALSO IS A TREND DOWN FROM PREVIOUS FORECASTS DUE TO A
DEEPER UPPER TROUGH OVER THE REGION TO END THE WEEK. ANOTHER STRONG
SURFACE RIDGE WILL BUILD INTO THE REGION THURSDAY AND FRIDAY AND
SHOULD KEEP THE END OF THE WEEK DRY.
PATTERN CHANGE OVER THE WEEKEND INTO NEXT WEEK...
OVER THE WEEKEND AND INTO EARLY NEXT WEEK, UPPER LOW IS PROGGED
TO DIG ACROSS THE WEST COAST WITH GENERAL DOWNSTREAM FLATTENING OF
THE UPPER LEVEL PATTERN. IN GENERAL, THIS WILL HELP TO GET
TEMPERATURES BACK TO NEAR THE SEASONAL NORMS BUT THERE IS
POTENTIAL FOR EVEN ABOVE NORMAL TEMPS TO RETURN. 500MB CLUSTER
ANALYSIS SHOWS TWO CAMPS OF THE OVERALL UPPER LEVEL PATTERN
EMERGING THROUGH THE WEEKEND. CAMP ONE IS A MORE OPEN WEST COAST
TROUGH WITH A ZONAL OR FLAT TROUGH PATTERN ALOFT. THIS CLUSTER IS
DOMINATED BY THE GEFS AND SUPPORTS MORE NORMAL TEMPS LOCALLY WITH
INCREASED PRECIP CHANCES. THE SECOND CAMP IS FOR A CLOSED H5 LOW
OVER SOCAL WITH FLAT RIDGING DOWNSTREAM EXTENDING INTO THE MID
MISSISSIPPI VALLEY. THIS CLUSTER IS DOMINATED BY THE ENS/GEPS
ENSEMBLES AND WOULD SUGGEST ABOVE NORMAL TEMPS LOCALLY AND A DRIER
WEEKEND AND START TO NEXT WEEK. WILL HAVE TO KEEP AN EYE ON MODEL
TRENDS TO SEE WHICH DIRECTION THE TWO CAMPS BEGIN TO CONVERGE.
DEUBELBEISS
AVIATION
(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY AFTERNOON)
ISSUED AT 1112 AM CST TUE JAN 21 2025
SURFACE HIGH PRESSURE WILL BEGIN TO EXIT THIS AFTERNOON, WITH
BLUSTERY LOW-LEVEL WINDS SHIFTING FROM WEST TO SOUTH THROUGHOUT
THE TAF PERIOD. THERE REMAINS SCATTERED MVFR CEILINGS THIS
AFTERNOON, ASSOCIATED WITH TRANSIENT FLURRIES, BUT VFR CONDITIONS
WILL BE THE RULE THROUGH WEDNESDAY MORNING.
MJA
ILX WATCHES/WARNINGS/ADVISORIES
EXTREME COLD WARNING UNTIL 3 PM CST THIS AFTERNOON FOR
ILZ027>031-036>038-040.
COLD WEATHER ADVISORY FROM 6 PM THIS EVENING TO 6 AM CST
WEDNESDAY FOR ILZ027>031-036>038-040>057-061>063-066>068-071>073.
COLD WEATHER ADVISORY UNTIL 3 PM CST THIS AFTERNOON FOR
ILZ041>057-061>063-066>068-071>073.
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