Area Forecast Discussion
Issued by NWS La Crosse, WI

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FXUS63 KARX 261801
AFDARX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
1201 PM CST FRI DEC 26 2014

.UPDATE...
ISSUED AT 1157 AM CST FRI DEC 26 2014

TEMPERATURES REALLY WARMING IN THE SUNSHINE AND HAVE DRIVEN UP
HIGHS TODAY 5F IN SWRN WI. CLOUDS SLOWLY SHIFTING EAST ON THE COLD
FRONT MOVING IN AND THIS WILL HALT WARM UP IN THE NWRN-CENTRAL FORECAST
AREA.

TONIGHT SNOW LOOKS ON TARGET BUT PERHAPS A BIT SLOWER. THE MAIN
ACCUMULATION PERIOD IS 3 AM TO 9 AM WHEN DEEP QG FORCING ALOFT
ASSOCIATED WITH FOUR CORNERS MID-UPPER TROPOSPHERIC LOW MOVES IN.
THE 6AM-9AM WINDOWS APPEARS TO BE THE HEAVIEST SNOW PERIOD. NOT
MANY CHANGES SEEN IN THE ADVISORY AREA OR AMOUNTS AT THIS
POINT...BUT A DELAY ON STARTUP OF AT LEAST 3 HOURS LOOKS LIKELY.
WILL COLLABORATE THIS CHANGE EARLY THIS AFTERNOON.

ONE OTHER ITEM WE ARE TRYING TO SORT OUT IS THE LIFT COMING IN
PRIOR TO DEEP SATURATION. THERE IS A DEEPER SURFACE BASED
SATURATED LAYER /LIQUID/ THAT COULD RESULT IN DZ/FZDZ PRIOR TO
SNOW ONSET. WILL TRY TO GET A HANDLE ON THAT THREAT IN THE EVENINGTO
SNOW ONSET TIME.

&&

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 357 AM CST FRI DEC 26 2014

CHALLENGES SURROUND SNOW CHANCES AND AMOUNTS TONIGHT INTO
SATURDAY WITH THE NEXT LOW PRESSURE SYSTEM. 26.00Z MODEL SUITE IN
GOOD AGREEMENT WITH THE SURFACE LOW TRACK...BUT DIFFER SOMEWHAT ON
THE PLACEMENT AND TIMING OF THE HIGHEST QPF. WILL LEAN TOWARD A
NAM/ECMWF BLEND WITH SUPPORT FROM THE SREF WHICH BEST MATCH
PRECIPITATION PLACEMENT WITH THE STRONGEST MID-LEVEL FORCING.

MAJORITY OF PRECIPITATION TODAY WILL REMAIN NORTH OF THE FORECAST
AREA ALONG TIGHT 850 TO 700 HPA THERMAL GRADIENT. ANYTHING THAT
DOES CREEP FAR ENOUGH SOUTH WILL LIKELY FALL AS DRIZZLE GIVEN WEAK
LIFT AND A DRY PROFILE ABOVE 1 TO 2 KM. TODAY WILL BE THE LAST
RELATIVELY MILD DAY FOR AWHILE WITH TEMPERATURES IN THE MID 30S
TO LOWER 40S.

PRECIPITATION EXPECTED TO DEVELOP RAPIDLY THIS EVENING AND
OVERNIGHT AS A SOUTHERN ROCKIES SHORT-WAVE MOVES INTO THE UPPER
MIDWEST AND INTERACTS WITH A SECONDARY WAVE DROPPING SOUTH ACROSS
THE SOUTHERN CANADIAN PRAIRIES. ASSOCIATED SURFACE LOW ACROSS
NORTHERN MO AT 27.06Z WILL RAPIDLY MOVE NORTH INTO SOUTHERN WI
SIX HOURS LATER. COLUMN TO QUICKLY SATURATE AND EXPECT DEFORMATION
PRECIPITATION AXIS FROM NORTHWEST IA INTO SOUTH-CENTRAL/SOUTHEAST
MN AND THEN INTO WEST-CENTRAL/NORTHERN WISCONSIN. THERMAL PROFILE
WILL BE COLD ENOUGH FOR ALL SNOW. LOWER SNOW RATIOS INITIALLY TO
RISE TO AROUND 14:1 BY SATURDAY MORNING WITH COOLING COLUMN. WITH
QPF AROUND TWO TO THREE TENTHS...EXPECT SNOW AMOUNTS TONIGHT
AROUND 1 TO 3 INCHES ALONG AND NORTHWEST OF A LINE FROM DODGE
CENTER TO WINONA TO WAUSAU.

.LONG TERM...(SATURDAY THROUGH THURSDAY)
ISSUED AT 357 AM CST FRI DEC 26 2014

LIGHT SNOW TO CONTINUE SATURDAY MORNING WITH AN ADDITIONAL 1 TO 2
INCHES POSSIBLE. WILL ISSUE A TWO-PART WINTER WEATHER ADVISORY FOR
2 TO 4 INCHES OF STORM TOTAL SNOW TONIGHT INTO SATURDAY. THE
FIRST PART INCLUDES DODGE/OLMSTED/WABASHA COUNTIES FROM 27.00Z TO
28.15Z AND THE SECOND PART FOR BUFFALO/TREMPEALEAU/JACKSON/TAYLOR/
CLARK COUNTIES FROM 27.03Z TO 28.18Z. A TIGHT GRADIENT IN
SNOWFALL IS EXPECTED FROM NORTH TO SOUTH ACROSS THESE COUNTIES
WITH SLICK ROAD CONDITIONS POSSIBLE THROUGH THE EVENT. COLD FRONT
TO DROP ACROSS THE FORECAST AREA SATURDAY BEGINNING THE DECLINE IN
TEMPERATURES WITH HIGHS 5 TO 8 DEGREES COLDER THAN TODAY.
NORTHWEST WIND TO PICK-UP BEHIND THE FRONT WITH OCCASIONAL GUSTS
TO 20 MPH. LINGERING LIGHT SNOW TO EXIT THE AREA BY SATURDAY
EVENING.

SUNDAY THROUGH THURSDAY...SYNOPTIC REGIME SHIFTS TO DRIER
NORTHWEST FLOW ALOFT AS A BROAD TROUGH TAKES UP RESIDENCE ACROSS
HUDSON BAY. THIS BRINGS LOW SNOW CHANCES MONDAY AND AGAIN THURSDAY
AS SHORT-WAVES ROTATE AROUND THE PARENT TROUGH...BUT NOT EXPECTING
ANY SIGNIFICANT ACCUMULATIONS. BIGGER STORY WILL BE MUCH COLDER
CONDITIONS. TEMPERATURES TO DROP DAILY AND BOTTOM OUT ON TUESDAY
WITH HIGHS IN THE SINGLE DIGITS TO TEENS ABOVE ZERO. ASSUMING SOME
DEGREE OF CLEARING...MANY LOCATIONS TUESDAY/WEDNESDAY MORNINGS
LIKELY TO DROP BELOW ZERO. TEMPERATURES WILL MODERATE SOMEWHAT BY
LATE WEEK WITH HIGHS BACK INTO THE 20S AND LOWS IN THE SINGLE
DIGITS.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON)
ISSUED AT 1157 AM CST FRI DEC 26 2014

ACCUMULATING SNOW PERIOD STILL FORECAST AT THE TAF SITES. HAVE
MOVED THE ONSET TIME LATER AT BOTH SITES WITH THE MAIN
ACCUMULATION AND IFR PERIOD...POSSIBLY LIFR IN THE 10-15Z WINDOW.

EXPECT THAT KRST WILL SEE MORE IMPACT WHERE 3-4 INCHES OF SNOW
COULD FALL. KLSE SHOULD SEE AROUND 2 INCHES OF SNOW. EXPECT VFR TO
RETURN SATURDAY AFTERNOON TO BOTH TAF SITES.

THERE IS A CHANCE OF DRIZZLE PRIOR TO SNOW ONSET THIS
EVENING...POSSIBLY FZDZ. WILL TRY TO GET A HANDLE ON THAT THREAT
THIS AFTERNOON.

&&

.ARX WATCHES/WARNINGS/ADVISORIES...
WI...WINTER WEATHER ADVISORY FROM 9 PM THIS EVENING TO NOON CST
     SATURDAY FOR WIZ017-029-032>034.

MN...WINTER WEATHER ADVISORY FROM 6 PM THIS EVENING TO 9 AM CST
     SATURDAY FOR MNZ079-086-087.

IA...NONE.
&&

$$

UPDATE...BAUMGARDT
SHORT TERM...ROGERS
LONG TERM....ROGERS
AVIATION...BAUMGARDT



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