697
FXUS63 KARX 040957
AFDARX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
357 AM CST TUE FEB 4 2025
KEY MESSAGES
- WINTRY PRECIPITATION LIKELY (60 TO 90%) WEDNESDAY AFTERNOON
THROUGH WEDNESDAY NIGHT. ACCUMULATING SNOW FOR MOST WITH
HIGHEST ACCUMULATIONS IN NORTH-CENTRAL WISCONSIN WHERE 1 TO 3
INCHES IS FORECAST. A GLAZE OF ICE IS POSSIBLE ALONG AND SOUTH
OF I-90.
- SNOW CHANCES RETURN FOR SATURDAY (60 TO 80% CHANCE). MOST
LIKELY SNOW RANGE .5" (SOUTHERN PART OF THE FORECAST AREA) TO
4" (NORTH OF I94), HOWEVER THERE ARE SOME LOW 10-15%
PROBABILITIES FOR GREATER THAN 4" NORTH OF I94. THIS STORM
SYSTEM IS STILL A WAYS OUT, THUS THE INTENSITY AND TRACK COULD
CHANGE.
- COLDER EARLY NEXT WEEK WITH ADDITIONAL LIGHT SNOW CHANCES.
COLDEST WIND CHILLS 0 TO -20.
DISCUSSION
ISSUED AT 356 AM CST TUE FEB 4 2025
TODAY-THURSDAY: BELOW NORMAL TEMPERATURES TODAY, SEASONABLE AND
WINTRY MIX PRECIPITATION FOR MIDWEEK:
A SHORTWAVE TROUGH TO OUR NORTH WILL CONTINUE MOVING EASTWARD
TOWARDS THE NORTHEAST AND MID-ATLANTIC REGIONS TODAY. WITH COLD AIR
ADVECTION REMAINING OVER THE AREA FROM THE COLD FRONT THAT MOVED
THROUGH ON MONDAY, TEMPERATURES WILL REMAIN BELOW NORMAL WITH HIGHS
GENERALLY IN THE TEENS TO LOW 20S. SHORTWAVE RIDGING COMES INTO THE
FRAME EARLY WEDNESDAY MORNING INTO THE AFTERNOON. DURING THE
AFTERNOON, A SHORTWAVE TROUGH WILL MOVE THROUGH THE AREA. CONFIDENCE
CONTINUES TO INCREASE IN PRECIPITATION OCCURRING, DURING THE
AFTERNOON AND THROUGH THE OVERNIGHT, WITH THIS SHORTWAVE AS ALMOST
ALL ENSEMBLE MEMBERS OF THE GEFS/GEPS/ENS SUITES SUPPORT MEASURABLE
PRECIPITATION.
WHILE ZONAL FLOW LOOKS LIKELY UP UNTIL THE RIDGING KICKS IN, SOME
SLIGHT WARM AIR ADVECTION ESTABLISHES ITSELF WITH THE LOW-LEVEL
SOUTHERLY FLOW ON WEDNESDAY. WHEN LOOKING AT SOUNDINGS ACROSS
NORTHEAST IOWA AND SOUTHWESTERN WISCONSIN, A WARM NOSE IS PRESENT,
INDICATING THE LOW-LEVEL WARM AIR ADVECTION. THE UNCERTAINTY LIES IN
HOW WARM AND HOW DEEP THIS AREA IS. THIS PARTICULAR UNCERTAINTY WILL
PLAY AN IMPORTANT ROLE IN WHAT PRECIPITATION TYPE OCCURS ACROSS MOST
OF THE FORECAST AREA. FOR AREAS ALONG AND SOUTH OF I-90 SOUNDINGS
SUGGEST THAT FREEZING DRIZZLE COULD BE POSSIBLE FOR A LONGER PERIOD
OF TIME THAN NORTH OF I-90. THIS IS SHOWN BY HOW DEEP THE WARM NOSE
IS IN CONJUNCTION WITH NO ICE PRESENT ALOFT FOR AN EXTENDED PERIOD
OF TIME. AS A RESULT, NBM PROBABILITIES FOR A GLAZE OF ICE FOR AREAS
SOUTH OF I-90 IS BETWEEN 30 AND 75% WITH THE HIGHER PROBABILITIES
THE FURTHER SOUTH YOU GO INTO NORTHEAST IOWA AND SOUTHWESTERN
WISCONSIN. THERE IS EVEN A 10 TO 30% CHANCE OF >0.1 INCHES OF ICE TO
OCCUR SOUTH OF I-90, WITH THE HIGHEST PROBABILITIES ALONG THE
SOUTHERN COUNTIES OF THE CWA. TO THE NORTH OF ROUGHLY I-90, SNOW
IS EXPECTED TO BE THE MAIN PRECIPITATION TYPE AS ICE REMAINS
PRESENT IN THE MID TO UPPER LEVELS THROUGH MOST OF THE EVENT,
EXCEPT THE TAIL END OF THE PRECIPITATION WHERE ICE MAY LOSE ITS
PRESENCE IN THE MID AND UPPER LAYERS, WHICH IS HOW FREEZING
DRIZZLE COULD OCCUR. EVEN FURTHER NORTH, ESPECIALLY IN NORTH-
CENTRAL WISCONSIN, ACCUMULATING SNOW WILL BE THE MAIN CONCERN.
PROBABILITIES FOR SEEING SNOW GREATER THAN 2 INCHES CONTINUES TO
RANGE BETWEEN 40 AND 80% ACROSS THIS AREA. OVERALL, MOST
LOCATIONS SHOULD SEE SOME ACCUMULATING SNOW WITH MOST RECEIVING
0.5 INCHES OR LESS FOR AREAS SOUTH OF I-90 AND BETWEEN 0.5 AND 1
INCH FOR AREAS NORTH OF I-90. FOR LOCATIONS IN CLARK AND TAYLOR
COUNTIES, A GENERAL RANGE OF 1 TO 3 INCHES IS POSSIBLE. AFTER
THIS SHORTWAVE MOVES THROUGH, COLD AIR ADVECTION FILTERS IN TO
HELP KEEP TEMPERATURES IN THE UPPER 20S TO MID 30S.
FRIDAY THROUGH THE WEEKEND:
SURFACE HIGH PRESSURE IS FORECAST ACROSS MUCH OF THE REGION FRIDAY
WITH A FAST WESTERLY FLOW ALOFT. AFTER LOWS BELOW ZERO AND IN THE
SINGLE DIGITS AND TEENS IN THE MORNING, TEMPERATURES SHOULD CONTINUE
TO BE SEASONAL IN THE TEENS AND 20S FOR HIGHS. A 500MB TROUGH OVER
THE WEST COAST IS FORECAST TO MOVE ACROSS THE NORTHERN ROCKIES
FRIDAY NIGHT AND INTO THE PLAINS AND UPPER MISSISSIPPI VALLEY
SATURDAY AND SATURDAY NIGHT. MEANWHILE, SURFACE LOW PRESSURE IS
ORGANIZING OVER THE SOUTHERN PLAINS AND TRACKS THROUGH THE OHIO
RIVER VALLEY TOWARD NEW ENGLAND. IN LOOKING AT THE 04.00 ENSEMBLES,
THE GEPS/ENS ARE SIMILAR WITH STRONGER AND BROADER WARM
ADVECTION COMPARED TO THE GEFS. HOWEVER, BOTH THE OPERATIONAL
GFS/EC PRODUCE AN AREA OF SNOW FROM THE DAKOTAS INTO THE UPPER
MISSISSIPPI VALLEY SATURDAY. THE MEAN 24HR GEFS QPF IS
0.10-0.20" WHILE THE GEPS/ENS ARE MORE 0.10-20" FROM NORTHEAST
IA TOWARD LSE, BUT THEN 0.20-0.30 FROM LSE TOWARD MDZ. THESE
AMOUNTS ARE SIMILAR TO THE 03.12Z RUN. WE ARE ON THE COLD SIDE
OF THE LOW, THUS THE PRECIPITATION WOULD BE ALL SNOW. SNOW
RATIOS ARE CURRENTLY 16 TO 20:1 ESPECIALLY ALONG AND NORTH OF
I90. THE MOSTLY LIKELY SNOW RANGE IS 1 TO 4" WITH HIGHEST
AMOUNTS NORTH OF I94, HOWEVER THERE ARE SOME PROBABILITIES OF
LESS THAN AN INCH FOR PARTS OF NORTHEAST IA AND SOUTHWEST WI 50
TO 70% AROUND PLATTEVILLE AND DUBUQUE. ALSO, SOME 10 TO 15%
PROBABILITIES OF HIGHER AMOUNTS OF 4 TO 6" NORTH OF I94. SHOULD
THIS BLANKET OF SNOW OCCUR, TEMPERATURES FOR SUNDAY/SUNDAY NIGHT
MAY HAVE TO BE ADJUSTED DOWNWARD. HIGHS SUNDAY ARE CURRENTLY
FORECAST TO BE IN THE TEENS AND 20S.
COLDER FOR EARLY NEXT WEEK:
REINFORCING COLD AIR ARRIVES MONDAY AND TUESDAY WITH READINGS ABOUT
10 DEGREES BELOW NORMAL. IT IS UNCERTAIN HOW THE NEXT TROUGH WILL
EVOLVE FOR MONDAY AND TUESDAY; WHETHER A STRONGER TROUGH OR A COUPLE
OF EMBEDDED TROUGHS. EITHER WAY, WE CONTINUE TO BE IN THE COLD AIR
WITH ADDITIONAL LIGHT SNOW POSSIBLE. THE WINDS ARE NOT REAL STRONG,
BUT DUE TO THE COLDER TEMPERATURES, LOWEST WIND CHILLS ARE CURRENTLY
FORECAST IN THE 0 TO -20 DEGREE RANGE.
AVIATION /06Z TAFS THROUGH 06Z WEDNESDAY/
ISSUED AT 1019 PM CST MON FEB 3 2025
WHILE THE POTENTIAL RETURN OF MVFR CEILINGS REMAINS A CONCERN
OVERNIGHT, PARTICULARLY NORTHEAST OF A EAU-82C LINE,
PROBABILITY OF OCCURRENCE AT RST/LSE HAS DECREASED COMPARED TO
THINKING AT LAST ISSUANCE, SO HAVE ONLY CARRIED FEW MENTIONS FOR
THE NEXT FEW HOURS. OTHERWISE, EXPECT PLENTY OF CLOUDS AT OR
AROUND 10 KFT TO CONTINUE THROUGH MUCH OF THE PERIOD. AS FOR
WINDS, INITIAL WINDS OUT OF THE NORTHWEST WILL TURN CLOCKWISE TO
OUT OF THE EAST OVER THE NEXT 18 HOURS.
ARX WATCHES/WARNINGS/ADVISORIES
WI...NONE.
MN...NONE.
IA...NONE.
DISCUSSION...CECAVA/ZAPOTOCNY
AVIATION...FERGUSON
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page