107
FXUS63 KARX 220442
AFDARX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
1042 PM CST TUE JAN 21 2025
KEY MESSAGES
- MODERATING TEMPERATURES, ESPECIALLY OVERNIGHT, ALTHOUGH BITTER
COLD LINGERS NORTHEAST THROUGH THE EVENING
- LIGHT SNOW CHANCES INCREASE OVERNIGHT INTO WEDNESDAY MORNING,
ESPECIALLY SOUTH
- BRIEF COOL DOWN AGAIN THURSDAY, BUT TEMPERATURES NEAR NORMAL
OR ABOVE THIS WEEKEND INTO EARLY NEXT WEEK
UPDATE
TONIGHT
ISSUED AT 1032 PM CST TUE JAN 21 2025
INCREASED THE WIND GUSTS WEST OF THE MISSISSIPPI RIVER INTO THE
35 TO 45 MPH RANGE. KRST HAS BEEN GUSTING INTO THE 40 TO 45 MPH
RANGE FOR THE PAST HOUR. IT LOOKS LIKE WE ARE MIXING TO THE TOP
OF MIXED LAYER. AS WARM AIR ADVECTION MOVES INTO THE AREA
DURING THE NEXT 3 HOURS, THIS MIXED LAYER WILL DECREASE AND SO
WILL OUR WIND GUSTS.
DISCUSSION
ISSUED AT 247 PM CST TUE JAN 21 2025
THE CURRENT PATTERN WILL MODIFY SOMEWHAT, WITH OUR RECENT
ARCTIC AIRMASS FINALLY RETREATING, HOW IT WON’T CHANGE A WHOLE
LOT WITH VARIED DEGREES OF NORTHWEST FLOW ALOFT THROUGH THE
REMAINDER OF THE PERIOD INTO EARLY NEXT WEEK. WARM ADVECTION WAS
INCREASING THROUGH THE DEPTH OF THE ATMOSPHERE THIS AFTERNOON WITH
NOTED THERMODYNAMIC FORCING AND SOME FRONTOGENETIC
CONTRIBUTIONS ARRIVING TOWARD MIDNIGHT. RECOVERY ALOFT WILL
OCCUR FASTER THAN THE LOW LEVELS WITH LINGERING DENSE/DRY AIR,
BUT EVENTUALLY AREAS OF LIGHT SNOW OR FLURRIES ARE EXPECTED TO
DEVELOP DURING THE OVERNIGHT HOURS INTO WEDNESDAY MORNING. HOWEVER
HIGHER BASED KINEMATIC SUPPORT IS EXPECTED TO ARRIVE TOMORROW
MORNING AS THE CURRENT PV STREAM ACROSS WA/ID/MT EVENTUALLY
REACHES THE MO RIVER VALLEY. THIS WILL INCREASE SNOW CHANCES
ACROSS THE SOUTH WITH ACCUMULATIONS OF AN INCH OR SO SOUTH.
ALTHOUGH WITH LESS EFFICIENT LIFT AND MORE MODEST MOISTURE
DEPTH, A FEW PERIODS OF LIGHT SNOW OR FLURRIES ARE ALSO POSSIBLE
FARTHER NORTH WITH ADEQUATE 1-2KM MOISTURE AND TEMPERATURES
STILL FAVORABLY COOL FOR FOR SNOW PRODUCTION EVEN THOUGH LIFT IS
MARGINAL. REGARDING TEMPERATURES, THE CURRENT FAR NORTHEAST COLD
ADVISORY IS SOMEWHAT MARGINAL, BUT THE SENSIBLE WEATHER
PERCEPTION WILL STILL BE COLD SO HAVE LEFT THAT HEADLINE
UNCHANGED FOR THE TIME BEING.
ALTHOUGH NOTHING TO THE DEGREE THAT WE HAVE SEEN OVER THE PAST
FEW DAYS, ANOTHER WEAK COLD FRONTAL PASSAGE WILL DIP
TEMPERATURES AGAIN SOMEWHAT INTO THURSDAY WITH LOWS JUST BELOW
ZERO BY DAYBREAK FRIDAY, THOUGH WIND CHILLS LOOK TO REMAIN ABOVE
ADVISORY CRITERIA. HOWEVER RETURN FLOW SHOULD BEGIN FRIDAY
STARTING WHAT LOOKS TO BE AT LEAST SEVERAL DAYS OF MORE MODERATE
TEMPERATURES, STAYING NEAR NORMAL OR JUST ABOVE. ALTHOUGH THE
FORECAST IS CURRENTLY DRY THIS WEEKEND, 06Z GEFS AND ESPECIALLY
EPS PROBABILITIES OF MEASURABLE PRECIPITATION DO INCREASE NORTH
TO GREATER THAN 50%, AS ANOTHER CANADIAN TROUGH CYCLES THROUGH
THIS SEMI-ACTIVE NORTHWEST FLOW PATTERN. THAT MAY BE A POSSIBLE
WINDOW FOR LIGHT SNOW CHANCES IF TRENDS PERSIST OVER THE NEXT
FEW MODEL RUNS.
BY EARLY NEXT WEEK THE PATTERN CHANGES A BIT WITH THE UPPER MS
VALLEY ON THE FRINGE OF THE GREAT LAKES/ONTARIO LONG WAVE TROUGH
AND A DEVELOPING SW CONUS CLOSED LOW. THIS SHOULD DEEP THE
FORECAST MAINLY DRY WITH SEASONAL TEMPERATURES IN PLACE.
AVIATION /06Z TAFS THROUGH 06Z THURSDAY/
ISSUED AT 1032 PM CST TUE JAN 21 2025
INCREASED THE WIND GUSTS WEST OF THE MISSISSIPPI RIVER INTO THE
35 TO 45 MPH RANGE. KRST HAS BEEN GUSTING INTO THE 40 TO 45 MPH
RANGE FOR THE PAST HOUR. IT LOOKS LIKE WE ARE MIXING TO THE TOP
OF MIXED LAYER. AS WARM AIR ADVECTION MOVES INTO THE AREA
DURING THE NEXT 3 HOURS, THIS MIXED LAYER WILL DECREASE AND SO
WILL OUR WIND GUSTS.
THE MODELS CONTINUE TO SHOW THAT A WEAK SHORTWAVE WILL MOVE
NORTH OF INTERSTATE 90 OVERNIGHT. WITH DEW POINT DEPRESSIONS OF
10 TO 15F, I AM A BIT CONCERNED ON WHETHER THE DRY AIR WILL BE
OVERCAME, SO KEPT THE SNOW CHANCES GENERALLY LESS THAN 30
PERCENT.
ANOTHER SHORTWAVE TROUGH WILL MOVE SOUTH OF INTERSTATE 90 ON
WEDNESDAY. THE CAMS ARE SHOWING MORE MOISTURE AND CYCLOGENESIS
WITH THAT WAVE. WITH THE MAJORITY OF THE CAMS SOUTH OF THE TAF
SITES, I PLAN ON NOT INCLUDING ANY VISIBILITY RESTRICTIONS.
MEANWHILE, SOUTH OF INTERSTATE 90, THESE ARE EXPECTED ALONG WITH
MAYBE A 1/2 TO 1 INCH OF SNOW.
ARX WATCHES/WARNINGS/ADVISORIES
WI...NONE.
MN...NONE.
IA...NONE.
UPDATE...BOYNE
DISCUSSION...CZ
AVIATION...BOYNE
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