502
FXUS63 KARX 021754
AFDARX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
1154 AM CST SUN FEB 2 2025
KEY MESSAGES
- FREEZING DRIZZLE EXITS THE AREA EARLY THIS MORNING WITH MILD TEMPERATURES
FOR THE AFTERNOON WITH HIGHS IN THE 40S. BE ALERT FOR ANY
SLICKS SPOTS EARLY THIS MORNING.
- SNOW AND WINTRY MIX MOVES IN ALONG AND NORTH OF I-90 TONIGHT
AND INTO MONDAY MORNING. SNOW ACCUMULATIONS OF 3 INCHES OR
MORE LIKELY (50-70%) NORTH OF HWY 29 IN TAYLOR COUNTY.
- COOLER TEMPERATURES EXPECTED TO START THE WORK WEEK WITH HIGHS
IN THE 20S AND 30S. CONFIDENCE INCREASING FOR PRECIPITATION
FOR THE MIDDLE OF THE WEEK, PRECIPITATION TYPES REMAIN
UNCERTAIN.
DISCUSSION
ISSUED AT 335 AM CST SUN FEB 2 2025
TODAY: FREEZING DRIZZLE EXITS EARLY WITH MILD TEMPERATURES
ONGOING FREEZING DRIZZLE CAN BE NOTED THIS MORNING WITH SEVERAL
OBSERVATION SITES SHOWING VISIBILITY REDUCTIONS ESPECIALLY ALONG AND
EAST OF THE MISSISSIPPI RIVER. THIS MIST/DRIZZLE WILL SLOWLY
PUSH ITS WAY EASTBOUND WITH SOME SLICK SURFACES IN ITS WAKE. AS
A RESULT, IF YOU ARE HEADING OUT EARLY THIS MORNING BE SURE TO
TAKE IT SLOW WHEN ENCOUNTERING ANY ICE COVERED ROADS. AS
TEMPERATURES QUICKLY WARM THIS MORNING AND INTO THE AFTERNOON
ANY SLICK SPOTS WILL IMPROVE WITH HIGHS IN THE 40S ACROSS MUCH
OF THE LOCAL AREA. WITH INCREASED CLOUD COVER TRENDS FOR THIS
AFTERNOON, HAVE DECREASED FORECAST HIGHS FOR MUCH OF THE AREA TO
ACCOUNT FOR THIS. THAT BEING SAID, IF ANY CLEARING MANAGES TO
OCCUR, DIURNAL MIXING MAY ALLOW OUR TEMPERATURES TO OVERACHIEVE
AS SHOWN IN THE HIGHER PERCENTILES OF THE NBM WITH TEMPERATURES
IN THE LOWER TO MIDDLE 50S ALONG AND SOUTH OF I-90.
THIS EVENING - MONDAY: ANOTHER ROUND OF SNOW, WINTRY MIX
ATTENTION THEN TURNS TONIGHT TO AN ELONGATED FRONTOGENETIC BAND
THAT WILL PUSH ALONG AND NORTH OF I-90. ONCE AGAIN THIS APPEARS
TO BE A MORE COMPLICATED P-TYPE CONUNDRUM THAN WHAT WE HAD LAST
NIGHT AND EARLY THIS MORNING. HOWEVER, THE FORCING SETUP HERE
IS A BIT DIFFERENT SO MIGHT BE SOME CAVEATS TO CONSIDER. THE
GENERAL CONCEPTUAL MODEL HERE SHOWN IN DETERMINISTIC GUIDANCE IS
SOME QG CONVERGENCE ALOFT AT 700-500MB WITH LOW-LEVEL
FRONTOGENESIS AT 800MB ASSOCIATED WITH A STATIONARY BOUNDARY
LOCATED JUST NORTH OF THE I-90 CORRIDOR. AS WE HEAD THROUGH THE
EVENING AND OVERNIGHT, THIS BOUNDARY REALLY DOES NOT BUDGE WITH
RAP/HRRR/ARW SOUNDINGS SHOWING A BI-MODAL LIFT PROFILE
CORRESPONDING WITH AFOREMENTIONED LIFTING MECHANISMS. IT IS
IMPORTANT TO NOTE THOUGH THAT THIS LIFT IS MORE ROBUST THAN WHAT
WE HAD WITH THIS PREVIOUS SYSTEM. AS FAR AS SATURATION IS
CONCERNED, IN NORTH-CENTRAL WI, HIGH CONFIDENCE THAT ICE IN THE
CLOUD IS MAINTAINED NORTH OF HWY 29 WHERE AN ALL SNOW SOLUTION
IS CURRENTLY EXPECTED IN TAYLOR COUNTY.
THE SATURATION BECOMES MORE MESSY FURTHER SOUTH WHERE YOU GET A
COMBINATION OF DRY LAYERS AND EVEN SOME MID-LEVEL WARMING. AS A
RESULT, THINKING THAT A WINTRY MIX IS MORE LIKELY AS OPPOSED TO SNOW
SOUTH OF HWY 29 AND TO THE I-90 CORRIDOR. GIVEN THE STRONG FORCING
REGIME INITIALLY, WOULD NOT RULE OUT SNOW TRANSITION TO FREEZING
DRIZZLE AS THE UPPER-LEVEL QG LIFT LESSENS. PRIMARY CONCERN GIVEN
THE STRONG LOW-LEVEL FORCING AND DEEPER SATURATION INTO MONDAY
MORNING WOULD SUGGEST THAT A PERIOD OF MORE ROBUST FREEZING
DRIZZLE WITH MEASURABLE ICE ACCUMULATIONS IN THIS AREA. HOWEVER,
THE RECENT HREF WOULD ONLY GIVE THIS ABOUT A 20 TO 30 PERCENT
PROBABILITY FOR MEASURABLE FREEZING PRECIPITATION TO OCCUR. THIS
FRONTOGENETIC FORCING SHIFTS EASTWARD AS WELL HEAD TOWARDS NOON
WHICH IS SHOWN IN THE CAMS PUSHING MUCH OF THE PRECIPITATION
EAST OF THE LOCAL AREA THROUGH THE LATE MORNING HOURS.
AS FAR AS AMOUNTS ARE CONCERNED, AGAIN KEEP IN MIND THAT THIS IS A
FRONTOGENETIC BAND SO THE AMOUNTS MAY SHIFT FROM CURRENT GUIDANCE.
THAT BEING SAID, ENSEMBLE GUIDANCE IS FAIRLY CONFIDENT ON AMOUNTS OF
OVER 3 INCHES WITH FAIRLY HIGH PROBABILITIES (50-70%) IN THE NBM IN
TAYLOR COUNTY. CONSIDERING THE FRONTOGENETIC NATURE OF THE SNOW,
NOTING 14-16:1 NBM SLRS AND THINK THAT IS FAIRLY APPROPRIATE. AS A
RESULT, HAVE GONE WITH A WINTER WEATHER ADVISORY IN TAYLOR COUNTY TO
ACCOUNT FOR THIS. AN ADVISORY WILL NEED TO BE CONSIDERED FURTHER
SOUTH IN CLARK COUNTY WHERE ADVISORY CRITERIA SNOWFALL MAY BE
REACHED AS WELL BUT HELD OFF ON THIS FORECAST CYCLE DUE TO THE CAMS
STILL SHIFTING FROM RUN TO RUN. FURTHERMORE, IF THE FREEZING DRIZZLE
SIGNAL AS MENTIONED PREVIOUSLY HOLDS, MAY NEED AN ADVISORY FURTHER
SOUTH TOWARDS THE I-90 CORRIDOR AS WELL.
TUESDAY - FRIDAY: SEASONABLE, PRECIPITATION CHANCES
LOOKING TO TUESDAY, SLIGHT UPPER-LEVEL NORTHWESTERLY FLOW AND COLD
AIR ADVECTION WILL COOL TEMPERATURES SOME WITH MEDIAN HIGH
TEMPERATURES IN THE GRAND ENSEMBLE (GEFS/EC/CANADIAN ENSEMBLE) BEING
IN THE TEENS TO MIDDLE 20S. HOWEVER, WITH SOME SUBTLE UPPER-LEVEL
RIDGING FOR WEDNESDAY HIGH TEMPERATURES TREND SLIGHTLY ABOVE AVERAGE
IN THE MIDDLE 20S TO MIDDLE 30S. OVERALL, COOLER THAN WHAT WE HAVE
SEEN THOUGH. AS FAR AS PRECIPITATION CHANCES, CURRENT DETERMINISTIC
GUIDANCE GFS/EC/CANADIAN SWINGS AND UPPER-LEVEL TROUGH NORTH OF THE
REGION INTO THE MIDDLE OF THE WEEK. HOWEVER, WHILE CONFIDENCE IS
INCREASING (50-80% CHANCE) FOR PRECIPITATION, A LARGE DEGREE OF
SPREAD ON HOW ANY FORCING WILL DEVELOP SO WILL KEEP IN ACCORDANCE
WITH THE NBM FOR NOW FOR WEDNESDAY AND THURSDAY WITH CONFIDENCE
IN ANY PRECIPITATION TYPE REMAINING LOW.
AVIATION /18Z TAFS THROUGH 18Z MONDAY/
ISSUED AT 1154 AM CST SUN FEB 2 2025
PESKY FOG AND LOW STRATUS IS STILL HOLDING ON AT THIS HOUR BUT
THERE IS SOME IMPROVEMENT SEEN JUST UPSTREAM VIA SATELLITE. IF
STRATUS MANAGES TO SCATTER WITHIN THE NEXT FEW HOURS (MORE
LIKELY AT RST), SHOULD SEE A PERIOD OF VFR THIS AFTERNOON INTO
EARLY EVENING.
MAIN FOCUS IS ON ANOTHER SYSTEM THAT WILL BRING MORE WINTRY
PRECIPITATION TO AREAS ROUGHLY NEAR AND NORTH OF I-90 TONIGHT
INTO MONDAY MORNING, WITH HIGHEST LIKELIHOOD (90%) OF SNOW NORTH
OF I-94. BOTH RST AND LSE WILL BE ON THE SOUTHERN FRINGES OF
THIS SYSTEM, BUT MODELS STILL MAINTAIN A FAIRLY DECENT SIGNAL
(30-40% CHANCE) FOR BOTH AIRFIELDS TO SEE LIGHT PRECIP IN THE
FORM OF -SN AND FZDZ/DZ (DEPENDING ON SFC TEMPS) BEGINNING
TOWARDS 06Z. PRECIP CHANCES WILL CONTINUE THROUGH MID-MORNING
ON MONDAY WITH THE POSSIBILITY FOR SOME LIGHT ICING.
CIGS WILL AGAIN BECOME MVFR TO IFR TONIGHT WITH VISIBILITY
IMPACTS FROM ANY LIGHT PRECIPITATION. COULD BE SOME AREAS OF FOG
AGAIN AS WELL.
ARX WATCHES/WARNINGS/ADVISORIES
WI...WINTER WEATHER ADVISORY FROM MIDNIGHT TONIGHT TO NOON CST
MONDAY FOR WIZ017.
MN...NONE.
IA...NONE.
DISCUSSION...NAYLOR
AVIATION...KURZ
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