972
FXUS63 KARX 062354
AFDARX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
554 PM CST TUE JAN 6 2026
KEY MESSAGES
- AREAS OF FOG WILL PERSIST THIS EVENING AND INTO THE OVERNIGHT
WITH LOCATIONS WEST OF THE MISSISSIPPI RIVER LIKELY (60-90%
CHANCE) SEEING VISIBILITIES OF 1/4 MILE OR LESS AT TIMES
OVERNIGHT.
- ABOVE NORMAL TEMPERATURES PERSIST FOR THE MIDDLE OF THIS WEEK
WITH HIGHS RANGING FROM THE MIDDLE 30S TO UPPER 40S.
- FIRST OF TWO SYSTEMS MOVES INTO THE REGION THURSDAY AND INTO
EARLY FRIDAY WITH RAIN TRANSITIONING TO SNOW, HOWEVER MINIMAL
SNOWFALL ACCUMULATIONS ARE CURRENTLY EXPECTED.
- A SECONDARY WINTER SYSTEM MOVES INTO THE REGION LATE FRIDAY
NIGHT AND INTO SATURDAY WITH ACCUMULATING SNOWFALL LIKELY.
THERE ARE MEDIUM PROBABILITIES (30-60% CHANCE) FOR SNOW
ACCUMULATIONS OF 3 INCHES OR GREATER ON SATURDAY.
DISCUSSION
ISSUED AT 147 PM CST TUE JAN 6 2026
REST OF TODAY - WEDNESDAY: FOG THIS AFTERNOON INTO TONIGHT,
CONTINUED ABOVE NORMAL TEMPERATURES
GOES-19 WATER VAPOR IMAGERY SHOWS TWO WEEK SHORTWAVES MOVING EAST OF
THE LOCAL AREA THIS AFTERNOON WHICH WERE RESPONSIBLE FOR THE
FREEZING RAIN ACROSS PORTIONS OF NORTH-CENTRAL WI THIS MORNING
AND EARLY AFTERNOON. IN THE WAKE OF THESE WAVES, WEAK
SUBSIDENCE, LIGHT WINDS AND SATURATED/SNOW-COVERED GROUND WILL
ENABLE FOG FORMATION THROUGHOUT THE REMAINDER OF THE DAY WITH
THE 06.12Z HREF HAVING FAIRLY HIGH PROBABILITIES FOR 1/4-MILE
VISIBILITIES WEST OF THE MISSISSIPPI RIVER. AS A RESULT, MAY
NEED TO HAVE A DENSE FOG ADVISORY INTO THE EVENING AND OVERNIGHT
IF OBSERVATIONAL TRENDS CONTINUE TO SUPPORT AREAS OF DENSE FOG
IN THIS REGION INTO THE OVERNIGHT.
WEDNESDAY WILL FEATURE QUASI-ZONAL WITH BROAD UPPER-LEVEL RIDGING
BEING THE MAIN SYNOPTIC MECHANISM DICTATING OUR CONDITIONS. AS A
RESULT, THIS IN COMBINATION WITH ONGOING LOW-LEVEL WARM ADVECTION
WILL ALLOW TEMPERATURES TO RISE WELL ABOVE NORMAL FOR THE MIDDLE
PORTION OF THIS WEEK. CURRENTLY, THE NBM HAS MEDIAN HIGH
TEMPERATURES RANGING FROM THE UPPER 30S TO MIDDLE 40S FOR MUCH OF
THE AREA ON WEDNESDAY WITH THE INTER-QUARTILE SPREAD RANGING FROM
THE MIDDLE 30S TO UPPER 40S. NEEDLESS TO SAY, WEDNESDAY WILL LIKELY
TREND 15 TO 20 DEGREES ABOVE NORMAL FOR MOST PLACES WITH THE 06.00Z
EXTREME FORECAST INDEX HAVING HIGH PROBABILITIES (60-90% CHANCE) FOR
EXCEEDING ECMWF M-CLIMATE REANALYSIS.
THURSDAY - SATURDAY: ACTIVE PATTERN, SNOW POTENTIAL FOR SATURDAY
THINGS BEGIN TO TURN MORE ACTIVE BY THE TIME THURSDAY ROLLS AROUND
AS A WEAK SHORTWAVE PIVOTS TOWARDS THE REGION ON THE WESTERN
PERIPHERY OF THE AFOREMENTIONED RIDGE WHICH WILL BE CENTERED OVER
THE EASTERN CONUS BY THURSDAY. AS THIS WAVE PUSHES INTO THE LOCAL
AREA, A FAIRLY DECENT SURFACE LOW PRESSURE CENTER IS PROGGED TO
DEVELOP WITH THIS SYSTEM INTO THE AFTERNOON AND EVENING ON THURSDAY.
HOWEVER, GIVEN THE FAIRLY WARM ANTECEDENT AIRMASS AND MINIMAL
UPSTREAM SUPPORT WITH ANY UPPPER-LEVEL WAVE OR LOW WITH THIS
SHORTWAVE, RAIN CURRENTLY APPEARS TO BE THE FAVORED
PRECIPITATION AT ONSET ON THURSDAY. ADDITIONALLY, THIS IS
SUPPORTED WITH 850MB TEMPERATURES GENERALLY REMAINING NEAR TO
SLIGHTLY ABOVE FREEZING THROUGHOUT THE DAY THURSDAY AND INTO
FRIDAY. THAT BEING SAID, A WEAK COLD FRONTAL PASSAGE IS PROGGED
BY DETERMINISTIC GUIDANCE TO PUSH THROUGH THE AREA OVERNIGHT
THURSDAY WHICH MAY BE JUST ENOUGH TO SWITCH US OVER TO SNOW FOR
A PERIOD (ALBEIT LIKELY A VERY WET SNOW GIVEN A 0C ISOTHERMAL
LAYER FROM 950 TO 850MB IN THE 06.12Z GFS) BEFORE A LULL IN
PRECIPITATION LIKELY ENSUES DURING THE DAYTIME HOURS ON FRIDAY.
EITHER WAY, PROBABILITIES FOR MEASURABLE SNOWFALL THURSDAY AND
INTO DAY ON FRIDAY LOOK TO BE ON THE LOWER-END (10-30% CHANCE)
IN THE GRAND ENSEMBLE (GEFS/EC/CANADIAN ENSEMBLE) ACROSS THE
LOCAL AREA. SO CURRENTLY NOT SEEING ANY SIGNAL FOR AN OVERLY
IMPACTFUL SYSTEM WITH THIS FIRST WAVE ON THURSDAY AND INTO
FRIDAY.
IT IS IMPORTANT TO UNDERSTAND THAT THIS IS JUST THE FIRST WAVE THAT
MOVES THROUGH THE AREA LATE THIS WEEK AS A SECONDARY SYSTEM WILL BE
WORTH WATCHING LATE FRIDAY AND INTO SATURDAY THAT FOLLOWS A SIMILAR
TRAJECTORY TO THE PREVIOUS SYSTEM AS IT EJECTS FROM THE SOUTHERN
ROCKIES AND TOWARDS THE MIDWEST LATE FRIDAY. AS IT APPROACHES
THE REGION, MUCH OF THE DETERMINISTIC AND ENSEMBLE GUIDANCE HAS
IT PHASING WITH A LARGER, SOUTHERN CANADIAN TROUGH THAT PUSHES
INTO THE NORTHERN PLAINS. OVERALL CLUSTER ANALYSIS OF THE GRAND
ENSEMBLE (GEFS/EC/CANADIAN ENSEMBLE) PAINTS TWO GENERAL
SCENARIOS, ONE WHERE THIS SYSTEM DOES PHASE WITH THIS UP-STREAM
TROUGH (ROUGHLY 77% OF MEMBERS IN THE GRAND ENSEMBLE) AND ONE
WHERE THESE DO NOT PHASE (ROUGHLY 23% OF MEMBERS IN THE GRAND
ENSEMBLE). STILL A LOT OF QUESTIONS SYNOPTICALLY WITH THIS
SYSTEM AS WITH THE PHASING UPPER- LEVEL WAVES SCENARIO COMES A
RAPIDLY INTENSIFYING 300MB JET STREAK IN THE EXIT REGION OF THE
AMPLIFIED TROUGH ACROSS THE MIDWEST AND GREAT LAKES SHOWN IN
DETERMINISTIC GUIDANCE. EXACTLY, HOW QUICKLY THIS STRENGTHENING
TAKES PLACE WILL BE KEY FOR HOW RAPIDLY SURFACE CYCLOGENESIS
TAKES PLACE AND THUS IMPACTING HOW THE DEFORMATION ZONE IN THE
LOCAL AREA MANIFESTS. REGARDLESS, WITH THE INJECTION OF COLD AIR
FROM THE CANADIAN WAVE, THERMAL PROFILES RESPOND ACCORDINGLY IN
THE 06.12Z GFS SOUNDINGS WHICH FAVOR AN ALL SNOW SCENARIO FOR
SATURDAY.
IN THE SCENARIO WHERE THESE WAVES DO PHASE, THERE IS FAIRLY
RESPECTABLE PROBABILITIES (30-60% CHANCE) IN THIS ENSEMBLE GROUP FOR
AMOUNTS OF 3 INCHES OR GREATER AS OPPOSED TO THE NON-PHASING
SCENARIO WITH VERY LOW PROBABILITIES (0-20% CHANCE) FOR SIMILAR
AMOUNTS. LOOKING EXPLICITLY AT THE EC ENSEMBLE, THE VAST
MAJORITY OF MEMBERS (ROUGHLY 90%) HAVE MEASURABLE SNOW INTO
SATURDAY. HOWEVER, GIVEN THAT THE 06.00Z EXTREME FORECAST INDEX
HAS A 0 SHIFT OF TAILS FOR SATURDAY ACROSS THE LOCAL AREA, THIS
IS SUGGESTING SOME HIGHER-END MEMBERS OF WHICH THE EC ENSEMBLE
HAS A FEW MEMBERS THAT SHOW AMOUNTS IN THE 8-12"+ RANGE. THIS
HIGHER END SCENARIO WOULD LIKELY BE CONTINGENT ON A FASTER
EVOLVING SURFACE LOW. REGARDLESS, THIS DEVELOPING SURFACE
FEATURE WOULD TRANSLATE NORTHEASTWARD LATER INTO SATURDAY AND
THUS LEAVING US PRECIPITATION FREE BY THE DAYTIME HOURS ON
SUNDAY.
THE BOTTOM LINE WITH THIS PERIOD IS IT LOOKS LIKE TWO SYSTEMS WILL
IMPACT THE REGION, THE FIRST BEING A RAIN TO SNOW TRANSITION
FAVORING MINIMAL ACCUMULATIONS ON THURSDAY AND EARLY FRIDAY. THE
SECOND HAVING SOME LARGER SPREAD IN POTENTIAL SNOWFALL AMOUNTS AT
THIS POINT BUT HAS MORE FAVORABLE DYNAMICS AND WOULD SUGGEST AN ALL
SNOW SOLUTION FOR SATURDAY. DEFINITELY WILL BE A PERIOD TO PAY
ATTENTION TO IN THE COMING DAYS AS FORECAST DETAILS WILL CONTINUE TO
BE REFINED.
AVIATION /00Z TAFS THROUGH 00Z THURSDAY/
ISSUED AT 550 PM CST TUE JAN 6 2026
WIDESPREAD IFR TO LIFR CEILINGS PERSIST FOR MUCH OF THE NIGHT
EAST OF THE MISSISSIPPI RIVER, WITH CLOUDS SLOWLY CLEARING FROM
WEST TO EAST WEST OF THE RIVER. HOWEVER, LIFR FOG MAY QUICKLY
FORM ONCE THE CLOUDS DEPART, WITH LOWER VISIBILITIES ELSEWHERE,
BUT HOW LOW IS IN QUESTION. THESE LOWER CEILINGS AND FOG CLEAR
OUT BY MIDDAY WEDNESDAY WITH VFR CONDITIONS LIKELY FOR THE
AFTERNOON. WINDS WILL BE LIGHT TONIGHT FROM THE WEST, SWITCHING
TO THE SOUTH AT 5-10 KTS FOR THE DAY ON WEDNESDAY.
ARX WATCHES/WARNINGS/ADVISORIES
WI...NONE.
MN...NONE.
IA...NONE.
DISCUSSION...NAYLOR
AVIATION...SKOW
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