779
FXUS63 KARX 301925
AFDARX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
125 PM CST TUE DEC 30 2025
KEY MESSAGES
- SOME PATCHY FREEZING DRIZZLE OR FLURRIES COULD BE AROUND
OVERNIGHT BUT IMPACTS SHOULD BE MINIMAL WITH SOME LIGHT
SNOWFALL TODAY AND SOME TREATMENT ON THE ROADS. WILL NEED TO
MONITOR FOR ADDITIONAL IMPACTS OR POSSIBLY A WINTER WEATHER
ADVISORY LATE THIS AFTERNOON AND EVENING BEFORE STRONGEST
FORCING EXITS.
- SOME ADDITIONAL LIGHT SNOW IS STILL EXPECTED WEDNESDAY AS THE
ARCTIC FRONT MOVES THROUGH FROM NORTH TO SOUTH EARLY. AMOUNTS
SHOULD BE LESS THAN 1/2 INCH AND ROUGHLY I-94 AND SOUTH.
TEMPERATURES WILL BE FALLING IN THE AFTERNOON.
- NEW YEARS EVE/DAY ONWARD: COLD WITH SINGLE DIGIT BELOW ZERO
WIND CHILLS NY EVE, HIGHS ONLY IN THE TEENS NY DAY. OTHERWISE,
SEASONABLE TEMPERATURES WITH LITTLE/NO PRECIPITATION EXPECTED
THROUGH WEDNESDAY.
DISCUSSION
ISSUED AT 125 PM CST TUE DEC 30 2025
PATCHY DRIZZLE OR FLURRIES TONIGHT
CHALLENGING FORECAST FOR TODAY BLEEDS INTO TONIGHT WITH STRONG
WARM ADVECTION IN THE 850-925MB LAYER SHIFTING EAST OF THE AREA
AND LIFT WANING PER SHORT TERM MODEL CONSENSUS. FOR THE LATER
AFTERNOON, AREAS WEST OF THE MISS RIVER HAVE SOME CHANCES (50%)
FOR FREEZING DRIZZLE AS THE CLOUD DEPTHS ARE FAVORING LOSS OF
ICE. THIS EVENING, LINGERING BOUNDARY LAYER MOISTURE APPEARS TO
REMAIN PER MODEL FORECAST SOUNDINGS WITH AROUND 1.5KM OF DEPTH
AND A SOMEWHAT MIXED SHALLOW BOUNDARY LAYER WITH WEAK COLD
ADVECTION OVERNIGHT. THIS 1.5KM SATURATED LAYER IN THE SOUNDINGS
IS PROBABLY (75% CHANCE) SUPERCOOLED LIQUID WITH MAINLY
SUBSIDENCE INDICATED. HOWEVER, WEST OF THE MISS RIVER, STEEPER
LOW-LEVEL LAPSE RATES ARE FOUND OVERNIGHT AGAIN PER CONSENSUS
MODEL OUTPUT WITH SOME WEAK COLD AIR ADVECTION, WHICH COULD
CAUSE SOME LIFT IN THAT LAYER...WHICH MAY ALSO JUST REACH ICE
NUCLEATION TEMPERATURES OF MINUS 10 TO 12C. SO, KIND OF MESSY TO
CALL DETERMINISTICALLY, BUT SOME VERY LIGHT PRECIPITATION COULD
FALL. IMPACTS WOULD BE LIMITED IT SEEMS WITH VERY LOW
PRECIPITATION AMOUNTS IF THEY OCCUR AT ALL. FOR NOW, HAVE
CARRIED SOME FREEZING DRIZZLE AND SNOW CHANCES (15-20%) ALONG I90
AND SOUTH BASICALLY. CONFIDENCE IS LOW ON THE OVERNIGHT PERIOD.
NEW YEARS EVE AND DAY - ADDITIONAL LIGHT SNOW
NORTHWEST FLOW CONTINUES WITH STRONG SHORTWAVE TROUGH ENERGY
MOVING THROUGH THE GREAT LAKES OFF TO THE NORTHEAST WEDNESDAY.
PER MULTI-MODEL ANALYSIS, THE UPPER TROPOSPHERIC QG CONVERGENCE
AND LIFT JUST BRUSHES CENTRAL WI. SURFACE OBSERVATIONS SHOW THE
ARCTIC FRONT CURRENTLY POSITIONED ALONG THE U.S.-CANADIAN
BORDER WITH SINGLE DIGIT TEMPERATURES ALONG IT FROM MN EAST. AS
THE TROUGH SWINGS THROUGH THE FLOW, THE ARCTIC FRONT IN LOWER
LEVELS DRIVES THROUGH THE AREA EARLY WEDNESDAY, BRINGING
BOUNDARY LAYER INSTABILITY AND STRONG COLD AIR ADVECTION / COOLING
TEMPERATURES. 700-800MB FRONTOGENESIS ALSO INTENSIFIES ACROSS
THE AREA WHICH ALL SHOULD ALLOW FOR DEEPER COLUMN SATURATION AND
A PERIOD OF LIGHT SNOW MOVING IN FROM THE NORTHWEST IN THE
MORNING, SNOWING IN THE 9AM TO 3PM WINDOW. IT WOULD SEEM THAT
I-94 AND SOUTH WOULD BE MOST FAVORED AND HAVE KEPT THE 60-70%
SNOW CHANCES. THIS MATCHES THE 30.12Z HREF 6-HOUR PROBABILITIES
FOR 0.01" (AXIS FROM MSP->MSN). AMOUNTS SHOULD GENERALLY BE LESS
THAN 1/2" AS THE FORCING IS TRANSIENT AND LIFT WEAK OVERALL
(MODEL CONSENSUS IN THE -3 TO -5UB/S RANGE).
FRIDAY THROUGH WEDNESDAY
WHILE THERE ARE SOME WEATHER SYSTEMS THAT COULD AFFECT THE AREA,
PREDICTABILITY IS PRETTY LOW ON THESE "LIGHTER" WEATHER MAKERS.
OVERALL, THE FORECAST IS NEARLY DRY THROUGH THIS PERIOD WITH
SEASONAL TEMPERATURES.
AVIATION /18Z TAFS THROUGH 18Z WEDNESDAY/
ISSUED AT 1118 AM CST TUE DEC 30 2025
A TRICKY AVIATION FORECAST IS IN THE CARDS OVER THE NEXT 6-12 HOURS
AS WE MONITOR A SYSTEM PUSHING THROUGH MINNESOTA THIS AFTERNOON
TOWARDS THE LOCAL AREA. EARLY THIS AFTERNOON EXPECTING A BREAK FROM
PRECIPITATION WITH MVFR TO LOW-VFR CIGS EXPECTED, THE MAIN QUESTION
IN THIS BREAK PERIOD WILL BE IF ANY FZDZ WILL BE PRESENT WITH A LOSS
OF CLOUD SATURATION AND RESIDUAL LIFT IN PLACE. HAVE NOT SEEN MANY
OBSERVATIONS SUGGESTING THIS SO HAVE LEFT OUT OF THE TAF FOR NOW BUT
WILL CONTINUE TO MONITOR. OTHERWISE, THIS SYSTEM WILL MOVE INTO THE
LOCAL AREA BY MID-AFTERNOON WITH HIGHEST PROBABILITY (40-80% CHANCE
IN THE 30.12Z HREF) FOR IFR TO LIFR VSBY REDUCTIONS FROM SNOW EAST
OF THE MISSISSIPPI RIVER. FURTHER WEST, CONFIDENCE REMAINS LOWER FOR
IFR VSBY REDUCTIONS AND THERE REMAINS SOME QUESTION IF SOME FZDZ
COULD OCCUR ON THE SOUTHWEST FLANK OF THIS SYSTEM WHERE SATURATION
ALOFT IS A QUESTION, PARTICULARLY INTO THE EVENING. OVERALL,
CONFIDENCE FOR FREEZING DRIZZLE IS ON THE LOW SIDE (15-30% CHANCE)
AND WOULD LIKELY BE PATCHY IN NATURE. LOW-MVFR TO IFR CIGS ARE
EXPECTED TO REMAIN IN PLACE OVERNIGHT WITH A SECONDARY CLIPPER
MOVING INTO THE REGION TOWARDS DAYBREAK ON WEDNESDAY BRINGING MVFR
TO IFR VSBY REDUCTIONS.
ARX WATCHES/WARNINGS/ADVISORIES
WI...NONE.
MN...NONE.
IA...NONE.
DISCUSSION...BAUMGARDT
AVIATION...NAYLOR
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