521
FXUS63 KARX 032354
AFDARX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
554 PM CST MON FEB 3 2025
KEY MESSAGES
- A ROUND OF WINTRY PRECIPITATION LIKELY (60-90%) WEDNESDAY AND
WEDNESDAY NIGHT WITH CONFIDENCE REMAINING MEDIUM/LOW ON EXACT
TYPES AND AMOUNTS.
- A SECOND SYSTEM IS EXPECTED TO MOVE THROUGH THE AREA ON
SATURDAY WITH THE PREDOMINANT PRECIP TYPE CURRENTLY LOOKING
TO BE SNOW. THE RANGE OF POSSIBLE AMOUNTS REMAINS HIGH AT THIS
TIME SO CONFIDENCE IS LOW ON EXPECTED TOTALS.
- MUCH COOLER AIR EXPECTED EARLY NEXT WEEK WITH HIGHS IN THE
TEENS TO MID 20S AND LOWS IN THE SINGLE DIGITS TO -10
DEGREES.
DISCUSSION
ISSUED AT 236 PM CST MON FEB 3 2025
WEDNESDAY - THURSDAY: SEASONABLE, MID-WEEK WINTRY PRECIPITATION
AS A LARGE UPPER LEVEL RIDGE BEGINS TO BUILD ACROSS THE SOUTHERN US,
WE WILL TRANSITION TO A MORE EAST/NORTHEASTERLY UPPER LEVEL FLOW
REGIME THROUGH THE MIDWEEK TIMEFRAME. DETERMINISTIC GUIDANCE
(03.00/12) NOTES A SHORTWAVE EJECTING EAST/NORTHEAST OUT OF THE
CENTRAL ROCKIES INTO THE UPPER MIDWEST DURING THE DAY ON
WEDNESDAY. PRECIPITATION CHANCES LOOK TO TAKE SHAPE AFTER 18Z
WEDNESDAY AS THERE WILL BE SOME SIGNIFICANT DRY AIR TO OVERCOME
IN THE LOWER 300 MB. ONCE WE CAN REALLY SATURATE THROUGH THE
PROFILE WEDNESDAY AFTERNOON/EVENING, WE MAY START TO SEE A
PRECIPITATION SHIELD BEGIN TO TAKE SHAPE. THE GRAND ENSEMBLE
(GEFS/EC/CANADIAN) CONTINUES TO INDICATE A HIGH POTENTIAL
(60-90%) FOR PRECIPITATION BETWEEN 18Z WEDNESDAY AND 12Z
THURSDAY. THE PICTURE GETS A LITTLE MORE COMPLICATED ONCE WE
START LOOKING INTO PRECIPITATION TYPES. CONFIDENCE HAS INCREASED
IN REGARDS TO THE CHIMNEY SEEING SOME ACCUMULATING SNOW WITH
NBM PROBABILITIES OF SEEING GREATER THAN OR EQUAL TO 2 INCHES OF
SNOW IN THE 40-80% RANGE. AS WE START MOVING SOUTH AND THE
TEMPERATURE PROFILES START TO WARM, WE START TO SEE A GREATER
CHANCE OF ICE ACCUMULATION. TAKING A GLANCE AT NAM MODEL
SOUNDINGS FOR LA CROSSE, WE SEE A SATURATED, SUB-FREEZING
PROFILE THROUGH AT LEAST 700 MB WITH AMPLE LIFT IN THE SURFACE
TO SFC-750 MB LAYER. UNFORTUNATELY, THIS PORTION OF THE PROFILE
STAYS BELOW THE DGZ, FAVORING A MORE FREEZING DRIZZLE TYPE OF
EVENT. EVEN FURTHER SOUTH, SOUNDINGS SHOW MORE OF A WARM NOSE,
WHICH FAVORS A MORE FREEZING RAIN/WINTRY MIX TYPE OF EVENT. NBM
PROBABILITIES OF SEEING AT LEAST A GLAZE OF ICE WEDNESDAY NIGHT
RANGE FROM ABOUT 35-65% SOUTH OF A ROCHESTER TO BLACK RIVER
FALLS LINE. IF WE UP THE AMOUNT OF ICE TO .10 OF AN INCH, THE
HIGHER PROBABILITIES STAY CLUSTERED ACROSS OUR SOUTHERN COUNTIES
ACROSS NORTHEASTERN IOWA AND FAR SOUTHWESTERN WISCONSIN. ALL OF
THIS TO SAY THAT MINOR CHANGES IN THE TEMPERATURE PROFILE COULD
SIGNIFICANTLY ALTER TO PRECIPITATION WE SEE ON THE GROUND. AS
WE START MOVING INTO THE REALM OF HI-RESOLUTION GUIDANCE,
HOPEFULLY WE WILL BE ABLE TO GET A BETTER HANDLE ON THE
TEMPERATURE PROFILES. SO FAR THE SOLUTION WE HAVE HIGHER
CONFIDENCE IN IS SNOW UP NORTH, A SNOW/FREEZING RAIN/DRIZZLE MIX
ACROSS THE I-90 CORRIDOR, AND BETTER CHANCES FOR ICE FURTHER
SOUTH.
AS THE SHORTWAVE TROUGH QUICKLY MOVES OFF THE EAST, PRECIPITATION
CHANCES GENERALLY LOOK TO COME TO AN END AFTER 12Z THURSDAY AS WE
DRY OUT THE LOW/MID-LEVELS WITH WINDS THROUGH THE PROFILE
SHIFTING TO THE NORTHWEST BEHIND A WEAK FRONTAL BOUNDARY. THIS
SHOULDN'T HAVE TOO MUCH OF AN IMPACT ON SURFACE TEMPERATURES FOR
THURSDAY WITH TEMPERATURES RANGING FROM THE LOWER 20S TO THE
NORTH AND WEST TO THE MID 30S TO THE SOUTH AND EAST. CONTINUED
COLD AIR ADVECTION WILL WORK TO COOL TEMPERATURES FOR FRIDAY
WITH HIGH TEMPERATURES ACROSS THE CHIMNEY FALLING INTO THE
TEENS.
SATURDAY - SUNDAY: SECOND SYSTEM TO BRING MORE SNOW
LOOKING AHEAD TO THE WEEKEND, THE GRAND ENSEMBLE IS INDICATING
ANOTHER SHORTWAVE TROUGH EJECTING OUT OF THE NORTHERN ROCKIES LATE
FRIDAY INTO SATURDAY. IN RESPONSE, A COLORADO LOW WILL MOVE OUT OF
THE PLAINS AND INTO THE MIDWEST. HOW THIS LOW PHASES FRIDAY INTO
SATURDAY WILL IMPACT OVERALL TOTALS WITH THIS SYSTEM. BOTH 03.06 EFS
AND THE 03.12 GEFS SHOW ACCUMULATING SNOWFALL WITH MOST OF THE
MEMBERS (50-80%) BUT THE WIDE RANGE IN TOTALS GIVES US PAUSE ON
ACCUMULATIONS THIS FAR OUT ESPECIALLY AS THE TRACK OF THE LOW IS
STILL SUBJECT TO CHANGE. THE CURRENT THINKING IS SOMEWHERE
BETWEEN 1-4 INCHES WITH THE HIGHER TOTALS ACROSS SOUTHEASTERN
MINNESOTA AND SOUTHWESTERN WISCONSIN BUT THESE ARE SUBJECT TO
CHANGE AS WE START TO GET CLOSER TO THIS EVENT.
MONDAY AND BEYOND: THE COLD RETURNS!
WITH SOME SNOW COVER EXPECTED ACROSS THE UPPER MIDWEST AND COLD
AIR ADVECTION EXPECTED TO CONTINUE THROUGH THE WEEKEND INTO
EARLY NEXT WEEK, WE'LL START TO SEE TEMPERATURES TAKE A HIT WITH
HIGHS ON MONDAY IN THE TEENS TO MID 20S ACROSS THE AREA. BY
TUESDAY MORNING, TEMPERATURES WILL RANGE FROM -10 IN THE CHIMNEY
TO AROUND 5 DEGREES ACROSS FAR SOUTHWEST WISCONSIN. LOOKING
JUST BEYOND THE SCOPE OF OUR FORECAST WE START TO SEE CHANCES
FOR HIGHS IN THE SINGLE DIGITS BY MID-WEEK WITH A COOLER PATTERN
FAVORED ACCORDING TO CPC 8-14 DAY OUTLOOK. THE NORTHWESTERN
HALF OF THE CWA CURRENTLY RESIDES IN THE CPC'S SLIGHT RISK FOR
HAZARDOUS COLD TEMPERATURES BETWEEN FEBRUARY 11-17. WE WILL
CONTINUE TO KEEP AN EYE ON THESE TEMPERATURES AS WE MOVE CLOSER
TO THIS WEEKEND.
AVIATION /00Z TAFS THROUGH 00Z WEDNESDAY/
ISSUED AT 543 PM CST MON FEB 3 2025
MVFR STRATUS IS THE PRIMARY CONCERN OVER THE NEXT 24 HOURS.
WHILE SATELLITE MONITORING IS GREATLY IMPAIRED BY THE PRESENCE
OF A HIGH DECK OF CLOUDS AT OR AROUND 20 KFT, SURFACE
OBSERVATIONS SUGGESTS ONGOING MVFR STRATUS IS ERODING NORTH TO
SOUTH, WITH RST/LSE CURRENTLY VFR. HOWEVER, AS THE EVENING GOES
ON, MVFR CEILINGS SHOULD RETURN BEFORE FINALLY DEPARTING BEFORE
12Z TUESDAY. ALONG WITH TIMING UNCERTAINTY, STILL SOME
UNCERTAINTY ON EXACT HEIGHT OF THESE CEILINGS WITH RESPECT TO
THE 2 KFT THRESHOLD FOR EXTRA FUEL AND ALTERNATE REQUIREMENTS,
SO AMENDMENTS MAY BE NEEDED THIS EVENING.
ARX WATCHES/WARNINGS/ADVISORIES
WI...NONE.
MN...NONE.
IA...NONE.
DISCUSSION...BARENDSE
AVIATION...FERGUSON
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