340
FXUS63 KARX 251143
AFDARX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
543 AM CST WED DEC 25 2024
KEY MESSAGES
- ABOVE AVERAGE TEMPERATURES PERSIST WELL INTO NEXT WEEK WITH
HIGHS FRIDAY TO SUNDAY RUNNING 10 TO 15 DEGREES ABOVE NORMAL
IN THE LOW TO EVEN MID 40S.
- INCREASING SIGNAL FOR FREEZING DRIZZLE DEVELOPING TONIGHT,
TRANSITIONING TO DRIZZLE AS TEMPERATURES CLIMB ABOVE FREEZING
THROUGH THE MORNING ON THURSDAY. UNTREATED ROADWAYS MAY BECOME
SLICK FOR THE THURSDAY MORNING COMMUTE.
- WET WEATHER FOR THURSDAY THROUGH SATURDAY WITH THE HEAVIEST
RAINFALL COMING ON FRIDAY.
DISCUSSION
ISSUED AT 310 AM CST WED DEC 25 2024
'TWAS THE NIGHT BEFORE CHRISTMAS AND AT THE WEATHER BUREAU,
SKY GRIDS FOR TODAY WERE BEING ASSIGNED 1 0 0.
FOR HIGH PRESSURE RIDGING IS KEEPING FLOW WEAK
AND THE CHANCES FOR SUN ARE LOOKING QUITE BLEAK.
THOUGH OVER CENTRAL WI AN AREA OF TRANSIENT CLEARING,
HAS EARLY THIS MORNING LED TO FOG AND LOW TEMPERATURES VEERING.
BUT THE NEWS FOR TODAY ISN'T ALL BAD,
FOR MILD TEMPERATURES SHOULD MAKE SOME FOLKS QUITE GLAD.
MOISTURE LIFTS NORTH TONIGHT, THIS MUCH IS CERTAIN.
BUT THE DRIZZLE POTENTIAL HIDES BEHIND A THIN CURTAIN.
NEARLY 1-KM IN DEPTH BOUNDARY-LAYER MOISTURE WILL BE,
ROUGHLY THE THRESHOLD FOR DRIZZLE WE NEED.
WEAK ISENTROPIC ASCENT AT 280K SHOULD EXIST,
SO COLLISION COALESCENCE CANNOT BE DISMISSED.
ATTENTION THEN TURNS TO WET BULBS FLIRTING WITH FREEZING,
SOMETHING EVERY FORECASTER WILL FIND VERY DISPLEASING.
A DEGREE OR TWO DIFFERENCE CAN CHANGE THINGS QUITE QUICK,
FROM SIMPLE LIGHT DRIZZLE TO MAKING ROADS SLICK.
NO THIS INDEED IS NOT VERY NICE,
THE HREF HAS A 30-50 PERCENT PROBABILITY FOR A GLAZE OF ICE.
THE GOOD NEWS IS WARMER AIR IS ON THE WAY,
AND BY THURSDAY MIDDAY THIS THREAT MELTS AWAY.
THE LATE WEEK PATTERN FEATURES MANY AN AMPLIFIED WAVE,
THE NEXT OF WHICH EJECTS NORTHWARD AND ARRIVES EARLY FRIDAY.
THIS WILL BRING OUR BEST SHOT OF ACCUMULATING RAIN,
WHICH MAKES OUR SNOWPACK TOUGH TO MAINTAIN.
NEARLY 1/2 AN INCH OF RAIN WE MAY RECEIVE,
WHICH 10-20% OF THE ENSEMBLE MEMBERS HAVE UP THEIR SLEEVE.
ABOVE THE FREEZING MARK DEWPOINTS WILL RISE,
INCREASING THE RISK OF DENSE FOG IN THE SKIES.
CLIMBING INTO THE MID-40S HIGHS ON SATURDAY WILL WARM,
A SOLID 10 TO 15 DEGREES ABOVE THE NORM.
CONFIDENCE IN THIS WARM SPELL IS QUITE ALRIGHT,
WITH THE NBM TEMPERATURES CLUSTERED VERY TIGHT.
LOOKING TO NEXT WEEK TEMPERATURES START TO COOL DOWN,
BUT NO MAJOR COLD SNAPS WILL BE LURKING AROUND.
CONSENSUS IN THE PATTERN NEXT WEEK BEGINS TO DEGRADE,
BUT THERE DOESN'T SEEM TO BE ANYTHING OF WHICH TO BE AFRAID.
FROM WFO LA CROSSE WHERE THE LIGHTS ALWAYS BURN BRIGHT,
MERRY CHRISTMAS TO ALL, AND TO ALL A GOOD NIGHT.
AVIATION /12Z TAFS THROUGH 12Z THURSDAY/
ISSUED AT 543 AM CST WED DEC 25 2024
MVFR/IFR CIGS WILL PREVAIL THROUGHOUT THE DAY TODAY WITH LOW-LEVEL
MOISTURE ABUNDANT IN THE LOWER ATMOSPHERE AT THIS TIME. WITH LITTLE
SUGGESTION FOR MUCH MODIFICATION TO THE PRESENT AIRMASS OVERHEAD,
HAVE KEPT PREVAILING MVFR AND IFR AT BOTH TAF SITES THROUGH AT
LEAST SUNSET. THERE IS A SMALL CHANCE (20-30% CHANCE) FOR LIFR
CIGS AS HINTED IN GUIDANCE LATER THIS MORNING AT KRST BUT HAVE
OPTED TO HOLD WITH IFR FOR NOW. AS WE HEAD TOWARDS THE EVENING
HOURS, LOW-LEVEL THETA-E ADVECTION WILL INSTIGATE SOME PATCHY
DRIZZLE ACROSS MUCH OF THE AREA INTO THE OVERNIGHT. WITH SURFACE
TEMPERATURES NEAR FREEZING, CANNOT RULE OUT SOME FREEZING
DRIZZLE (30-50% CHANCE) INTO THURSDAY MORNING. ADDITIONALLY,
WITH HIGHER DEWPOINTS BEING ADVECTED NORTHWARD, CATEGORY
REDUCTIONS WILL LIKELY TANK TO IFR/LIFR OVERNIGHT AS CIGS BEGIN
TO DROP. TOWARDS THE AFTERNOON ON THURSDAY WILL NEED TO MONITOR
FOR EVEN VLIFR CONDITIONS WITH THE 25.00Z HREF HAVING
INCREASING PROBABILITIES (40-70%) FOR 1/4SM VSBYS BY 18Z WITH
INCREASING DEWPOINTS MOVING OVER THE PRESENT SNOWPACK RESULTING
IN LIKELY FOG FORMATION.
ARX WATCHES/WARNINGS/ADVISORIES
WI...DENSE FOG ADVISORY UNTIL 6 AM CST EARLY THIS MORNING FOR
WIZ043-044.
MN...NONE.
IA...NONE.
DISCUSSION...SKOW
AVIATION...NAYLOR
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