916
FXUS63 KARX 031735
AFDARX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
1135 AM CST MON FEB 3 2025
KEY MESSAGES
- SNOW CONTINUES IN CLARK AND TAYLOR COUNTIES THIS MORNING WITH
SNOWFALL RATES OF 1 TO 1.5" PER HOUR AT TIMES. STORM TOTAL SNOWFALL
AMOUNTS OF 2 TO 6 INCHES ARE EXPECTED WITH LOCALLY HIGHER
AMOUNTS POSSIBLE.
- FREEZING DRIZZLE IS POSSIBLE (20-50% CHANCE) SOUTHEAST MN AND
WEST-CENTRAL WI THIS MORNING BEFORE PRECIPITATION EXITS BY
NOON.
- SECOND ROUND OF WINTRY PRECIPITATION LIKELY (60-90%) WEDNESDAY
AND WEDNESDAY NIGHT WITH CONFIDENCE REMAINING LOW ON EXACT
TYPES AND AMOUNTS. ADDITIONAL SNOW CHANCES (40-60%) RETURN
SATURDAY AS WELL.
DISCUSSION
ISSUED AT 345 AM CST MON FEB 3 2025
TODAY: COOLER WITH SNOW, WINTRY MIX THIS MORNING
SNOW IS CURRENTLY ONGOING NEAR AND NORTH OF I-94 WITH MANY
OBSERVATION SITES SUCH AS EAU CLAIRE, WI, BLACK RIVER FALLS, WI AND
WAUSAU, WI REPORTING SNOW AT TIMES TONIGHT. AS WE HEAD THROUGH THE
REST OF THE MORNING, A FEW THINGS WILL NEED TO BE MONITORED. A
BOUNDARY WILL VERY SLOWLY MOVE SOUTH THIS MORNING AND AFTERNOON WITH
INCREASING 700MB WARM ADVECTION OUR AHEAD. AS A RESULT, THIS
ENHANCED BAROCLINICITY WILL MAINTAIN A STRONG 600-800MB
FRONTOGENETIC SIGNAL THAT CAN BE NOTED OVER THE DAKOTAS AND WESTERN
MINNESOTA THAT PUSHES NORTH OF I-94 INTO CLARK AND TAYLOR COUNTY BY
AROUND SUNRISE. AS THIS OCCURS, SNOWFALL RATES WILL INCREASE WITH
THE 03.06Z HRRR SHOWING SNOWFALL RATES OF 1" TO 1.5" AT TIMES. AS A
RESULT, HAVE STORM TOTAL AMOUNTS TO ANYWHERE FROM 4 TO 6 INCHES
WITHIN TAYLOR COUNTY AND LESSER AMOUNTS POINTS SOUTH. ALTHOUGH
GIVEN THE HIGHER RATES AND MINIMAL SNOW TO LIQUID RATIO SPREAD
IN THE NBM (14-16:1 FOR THE 10TH TO 90TH PERCENTILE), SOME
LOCALLY HIGHER AMOUNTS OF 6 INCHES MAY BE POSSIBLE.
SPOTTY DRIZZLE HAS BEEN NOTED ON SURFACE OBSERVATIONS THROUGHOUT THE
NIGHT, HOWEVER GIVEN SURFACE TEMPERATURES SOUTH OF I-94 HAVE
GENERALLY REMAINED ABOVE FREEZING SO FAR. THAT BEING SAID, AS
TEMPERATURES COOL MARGINALLY THIS MORNING AS THE AFOREMENTIONED
BOUNDARY MOVES SOUTH AND CLOUD ICE REMAINS ABSENT AS SHOWN IN
RAP/HRRR SOUNDINGS, THE FREEZING DRIZZLE THREAT REMAINS IN SOUTHEAST
MN AND WEST-CENTRAL WI ON ELEVATED SURFACES AND IN MORE TYPICAL
COOLER SPOTS. REGARDLESS, MUCH OF THE CAMS AGREE ON KICKING THE
PRECIPITATION TO THE CURB BY AROUND NOON LEAVING AFTERNOON
TEMPERATURES GENERALLY IN THE 20S AND 30S AREAWIDE AND FALLING INTO
THE SINGLE DIGITS AND TEENS OVERNIGHT.
TUESDAY - THURSDAY: SEASONABLE, MID-WEEK WINTRY PRECIPITATION
AS WE HEAD INTO TUESDAY UNIFORM NORTHWESTERLY FLOW WILL AID IN
DROPPING OUR TEMPERATURES SOME WITH HIGHS GENERALLY IN THE TEENS TO
MIDDLE 20S. GIVEN THAT NBM HAS STRUGGLED TO KEEP UP WITH RAW
GUIDANCE, HAVE COOLED TEMPERATURES DOWN SLIGHTLY EARLY THIS WEEK.
OVERALL, ZONAL FLOW WITH MAYBE SOME SUBTLE UPPER-LEVEL RIDGING WILL
DOMINATE THE UPPER-LEVEL FLOW PATTERN THROUGH THE MIDDLE OF THE WEEK
KEEP OUR TEMPERATURES NEAR NORMAL, PERHAPS SLIGHTLY ABOVE HEADING
INTO WEDNESDAY AND THURSDAY. THE KEY PERIOD FOR THE MIDDLE OF THE
WEEK WILL BE TWO SHORTWAVES NOTED IN DETERMINISTIC GUIDANCE (02.00Z
GFS/EC) THAT MOVE EAST-NORTHEASTBOUND IN THIS FLOW. THE KEY QUESTION
WILL BE HOW THEY INTERACT AS TO HOW ROBUST ANY PRECIPITATION
WILL BE FOR OUR AREA BUT THERE REMAINS A VERY STRONG SIGNAL IN
THE GRAND ENSEMBLE (GEFS/EC/CANADIAN) FOR PRECIPITATION ON
WEDNESDAY AND THURSDAY. PROBABILITIES REMAIN VERY HIGH (80-100%)
FOR MEASURABLE PRECIPITATION IN THE AFOREMENTIONED ENSEMBLE
GUIDANCE, HOWEVER HIGHER AMOUNTS OF 0.1" OR GREATER WILL BE
DICTATED BY HOW THESE WAVES INTERACT WITH ONLY MEDIUM
PROBABILITIES (30-70%) IN THE GRAND ENSEMBLE (GEFS/EC/CANADIAN
ENSEMBLE).
THE NBM HAS BEEN VERY INSISTENT ON A FREEZING DRIZZLE/RAIN SCENARIO
WITH HIGH PROBABILITIES (50-80%) FOR MEASURABLE FREEZING RAIN SOUTH
OF I-90 THROUGH THURSDAY MORNING. THAT BEING SAID, THE GRAND
ENSEMBLE CLUSTER ANALYSIS SHOWS THIS POINT OF UNCERTAINTY MORE
VIVIDLY WITH THE STRONG TROUGHING REGIME (ROUGHLY 33% OF MEMBERS)
HAVING RELATIVELY HIGH PROBABILITIES (30-50%) FOR MEASURABLE
FREEZING RAIN SOUTH OF I-90 AS OPPOSED TO OTHER SOLUTIONS WHICH ARE
FAR LOWER. THIS UNCERTAINTY FURTHER SUGGESTED IN THE 03.00Z GFS
SOUNDINGS AT LA CROSSE WHICH WOULD PAINT AN ALL OR MOSTLY SNOW
SOLUTION AS THE WARM NOSE ALOFT GENERALLY DOES NOT WARM ABOVE
FREEZING AND HAS COMPLETED SATURATION. THIS IS CONTRASTED BY THE NAM
WHICH WOULD SHOW A PERIODIC LOSS OF CLOUD ICE SUGGESTING A MORE
WIDESPREAD FREEZING DRIZZLE SETUP FOR THE SOUTHERN TWO-THIRDS
OF THE AREA WITH PERIODS OF SNOW/SLEET MIXED IN IF UPPER-LEVEL
SATURATION CAN OCCUR. AS YOU HEAD FURTHER NORTH IN THIS
SOLUTION, YOU GET SOME UPPER-LEVEL SUPPORT FROM THE NORTHERN
WAVE WHICH WOULD AID IN KEEPING AN ALL SNOW SOLUTION. SO
OVERALL, HAVE HIGH CONFIDENCE THERE WILL BE SOME WINTRY
PRECIPITATION AROUND FOR WEDNESDAY AND INTO THURSDAY THAT WILL
LEAD TO SOME SNOW/ICE ACCUMULATIONS IN THE LOCAL AREA. HOWEVER,
HAVE LOW CONFIDENCE ON THE EXACT PRECIPITATION TYPE OTHER THAN
THAT THE FURTHER NORTH YOU HEAD THE MORE LIKELY TO SEE PRIMARILY
SNOW, ESPECIALLY NORTH OF I-94.
FRIDAY - SUNDAY: STILL SEASONABLE WITH WEEKEND SNOW CHANCES
AS WE HEAD INTO FRIDAY AND THE WEEKEND, ZONAL FLOW PERSISTS WITH
MEDIAN HIGH TEMPERATURES IN THE GRAND ENSEMBLE REMAINS NEAR
CLIMATOLOGICAL NORMALS. THE NEXT SYSTEM THAT WILL WARRANT SOME
MONITORING WILL BE A SHORTWAVE THAT WILL PUSH EASTWARD FROM THE
ROCKIES AND ACROSS THE NORTHERN PLAINS. OVERALL, THERE ALREADY
REMAINS A FAIRLY STRONG CONSENSUS THAT SOME PRECIPITATION,
LIKELY SNOW, WILL BE PRESENT WITH 60-80% PROBABILITIES FOR
MEASURABLE SNOW IN THE GRAND ENSEMBLE (40-60% FOR OVER 1 INCH!).
GRANTED WHILE THERE REMAINS SOME DISTINCT TIMING DIFFERENCES
BETWEEN THE GLOBAL MODELS (GFS/EC/CANADIAN) THINKING THE LIKELY
MENTION FOR PRECIPITATION CHANCES IN THE NBM IS APPROPRIATE.
AVIATION /18Z TAFS THROUGH 18Z TUESDAY/
ISSUED AT 1135 AM CST MON FEB 3 2025
AS A TROUGH MOVES SOUTH THROUGH THE AREA, AREAS OF FREEZING
DRIZZLE WILL CONTINUA INTO THE EARLY AFTERNOON ALONG AND SOUTH
OF INTERSTATE 90. THIS PRECIPITATION SHOULD END AROUND 03.19Z
NEAR INTERSTATE 90 AND AROUND 03.21Z ACROSS NORTHEAST IOWA AND
SOUTHWEST WISCONSIN.
AS THE 925-850 RIDGE AXIS SLIDES SOUTH ACROSS THE AREA THIS
EVENING, THE MVFR CEILINGS WILL IMPROVE TO VFR.
SUSTAINED WINDS WILL REMAIN IN THE 10 TO 20 KNOT RANGE WITH
GUSTS OF 20 TO 30 KNOTS THROUGH THIS AFTERNOON. THESE WINDS
WILL BE FROM THE NORTHEAST AND NORTH. FOR TONIGHT, WE WILL LOSE
THE GUSTS, BUT STILL SEE SUSTAINED WINDS IN THE 10 TO 20 KNOT
RANGE. THE WIND DIRECTION WILL CHANGE FROM NORTH TO NORTHWEST.
ARX WATCHES/WARNINGS/ADVISORIES
WI...NONE.
MN...NONE.
IA...NONE.
DISCUSSION...NAYLOR
AVIATION...BOYNE
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