Area Forecast Discussion
Issued by NWS La Crosse, WI

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000
FXUS63 KARX 260938
AFDARX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
338 AM CST WED NOV 26 2014

.SHORT TERM...(TODAY THROUGH TONIGHT)
ISSUED AT 338 AM CST WED NOV 26 2014

CURRENT WATER VAPOR IMAGERY SHOWS A VIGOROUS MID-LEVEL
TROUGH/CIRCULATION CENTERED OVER SOUTHWEST MN...MOVING SOUTHEAST.
ISENTROPIC PUSH/850-500MB FRONTOGENESIS OUT AHEAD OF THE WAVE WAS
PRODUCING A COUPLE BANDS OF LIGHT-MODERATE SNOW ACROSS SOUTH-
CENTRAL INTO SOUTHEAST MN AND CENTRAL IA...MOVING NORTHEAST
TOWARD/INTO THE CURRENT WINTER WEATHER ADVISORY. A WINTER WEATHER
ADVISORY IS IN EFFECT THROUGH TODAY/6PM FOR DODGE AND MOWER COUNTIES
IN SOUTHEAST MN AND MITCHELL/FLOYD/CHICKASAW COUNTIES IN NORTHEAST
IA. THERE WILL LIKELY BE A FAIRLY TIGHT EAST TO WEST GRADIENT IN
SNOWFALL THROUGH TODAY DUE TO FRONTOGENESIS DYING OUT AS IT MOVES
NORTHEAST AND POTENTIAL COLUMN SATURATION ISSUES DUE TO DRIER SUB-
CLOUD LAYER THE FARTHER EAST YOU GO. IN THE ADVISORY...THINKING
ANYWHERE FROM 2-4 INCHES IS POSSIBLE...AGAIN WITH HIGHER-END AMOUNTS
IN THE WESTERN FRINGES OF THE ADVISORY. FARTHER EAST...MAINLY UP TO
THE MISSISSIPPI RIVER...ANYWHERE FROM A DUSTING TO AROUND AN INCH
COULD OCCUR. LOOK FOR MAIN FORCING FROM THIS WAVE TO MOVE SOUTHEAST
THIS AFTERNOON...SO EXPECTING A DIMINISHING TREND IN THE SNOW.

MEANWHILE...WILL BE WATCHING AN ARCTIC FRONT DROP SOUTHEAST THROUGH
MN INTO WESTERN WI THIS AFTERNOON...AND THIS IS EXPECTED TO GENERATE
SOME SNOW SHOWER ACTIVITY AS IT PUSHES SOUTHEAST INTO/THROUGH THE
AREA LATER THIS AFTERNOON INTO THIS EVENING. COULD SEE 1/2-1 INCH OUT
OF THIS SNOW SHOWER ACTIVITY BEFORE IT WRAPS UP/EXITS THE AREA SOON
AFTER MIDNIGHT.

OTHERWISE...PLAN ON HIGHS MAINLY IN THE 20S TODAY. LOOK FOR LOWS
TONIGHT RANGING FROM THE SINGLE DIGITS TO THE TEENS WITH CLEARING
SKIES AS ARCTIC AIR SPILLS INTO THE REGION. COULD EVEN SEE A FEW
READING NEAR ZERO OR A COUPLE DEGREES BELOW ZERO ACROSS MN.

.LONG TERM...(THURSDAY THROUGH TUESDAY)
ISSUED AT 338 AM CST WED NOV 26 2014

FOR THANKSGIVING DAY...LOOK FOR SUNNY BUT COLD CONDITIONS AS
MODIFIED ARCTIC AIRMASS SLIDES ACROSS THE AREA. HIGHS ARE EXPECTED
TO ONLY TOP OFF IN THE TEENS.

A WARM FRONT WILL BE APPROACHING THE REGION THURSDAY NIGHT AND
PUSHING THROUGH DURING THE DAY FRIDAY. SIGNAL FOR LIGHT SNOWFALL
THURSDAY NIGHT WAS SUCH THAT WENT WITH CATEGORICAL POPS AFTER
MIDNIGHT FOR AREAS ALONG/NORTHEAST OF I-94. ACROSS THAT AREA...1-2
INCHES OF SNOWFALL LOOKS LIKELY.

DURING THE DAY FRIDAY AS THE WARM FRONT IS PUSHING THROUGH...MODEL
SOUNDINGS ARE INDICATING THERE MAY BE A LOSS OF ICE IN THE CLOUD FOR
SNOW GENERATION...TURNING INTO A FREEZING DRIZZLE THREAT. HAVE ADDED
A SLIGHT CHANCE OF FREEZING DRIZZLE IN THE GRIDS BASED ON THIS
SIGNAL. OTHERWISE...LOOK FOR A CLOUDY DAY WITH HIGHS TOPPING OFF IN
THE 20S TO THE LOWER 30S. LIGHT SNOW/FREEZING DRIZZLE CHANCES LINGER
NORTH OF I-94 FRIDAY NIGHT AS THE WARM FRONT HANGS UP ACROSS THAT
AREA WITH THE NAM MODEL INDICATING A WEAK MID-LEVEL TROUGH RIPPLING
THROUGH AS WELL.

SATURDAY LOOKS TO BE RELATIVELY MILD IN THE WARM SECTOR OF LOW
PRESSURE SYSTEM MOVING ACROSS THE DAKOTAS/NORTHERN MN. LOOK FOR
HIGHS IN THE 30S TO THE LOWER 40S WHICH IS SOME 5 DEGREES ABOVE
NORMAL FOR THAT DATE.

ANOTHER ARCTIC FRONT SLIPS SOUTHEAST ACROSS THE AREA SATURDAY
NIGHT/SUNDAY. IT APPEARS THIS FRONT WILL COME TROUGH DRY THIS
TIME...BUT TEMPERATURES WILL BE HEADING DOWNWARD WITH HIGHS SUNDAY
IN THE TEENS AND 20S.

ARCTIC AIRMASS LINGERS OVER THE AREA MONDAY. DESPITE SUNSHINE...PLAN
ON HIGHS IN THE TEENS AND 20S.

AS THE HIGH/MODIFIED ARCTIC AIRMASS PUSHES EAST ON TUESDAY...WARM
AIR ADVECTION TAKES OVER AS LOW PRESSURE MOVES ACROSS THE DAKOTAS
TOWARD THE REGION. THIS COULD PRODUCE LIGHT RAIN OR SNOW AS HIGHS
CLIMB INTO THE 30S.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z WEDNESDAY NIGHT)
ISSUED AT 1115 PM CST TUE NOV 25 2014

THE 26.00Z KDVN SOUNDING SHOWED A CONSIDERABLE AMOUNT OF DRY AIR
IN THE LOW LEVELS THAT WILL CONTINUE TO GET DRAWN INTO THE AREA ON
THE SOUTH WINDS AHEAD OF THE APPROACHING SURFACE LOW. DEW POINT
DEPRESSIONS ARE BETWEEN 5 AND 10 DEGREES AS FAR WEST AT THE
MISSOURI RIVER AS OF 26.05Z. WHILE THERE WAS LITTLE CHANGE IN THE
OVERALL FORCING SIGNALS IN THE 26.00Z NAM AND GFS...THIS DRY AIR
WILL HELP TO DELAY THE ARRIVAL OF ANY SNOW FROM THIS SYSTEM. THE
ONE TREND NOTED IN THE MODELS WAS A SOUTHWESTWARD SHIFT IN THE
SNOW DUE TO THE DRY AIR. HAVE THUS PUSHED BACK THE ARRIVAL TIME OF
THE SNOW AND WILL NOW SHOW FLURRIES COMING INTO KRST DURING THE
MID MORNING HOURS BEFORE GOING DOWN WITH IFR VISIBILITIES AND MVFR
CEILINGS FOR A GOOD SHARE OF THE AFTERNOON. THE FORCING SHOULD
QUICKLY DIMINISH WEDNESDAY EVENING AS THE SHORT WAVE TROUGH MOVES
PAST AND BROUGHT THE VISIBILITY UP TO VFR BUT KEPT THE CEILINGS
DOWN AS THE NAM BUFKIT SOUNDINGS SUGGEST THE LOW LEVELS UNDERNEATH
THE INVERSION SHOULD STAY SATURATED. ALSO DELAYED THE ARRIVAL OF
THE SNOW AT KLSE WITH THE FLURRIES COMING IN DURING THE AFTERNOON
WITH A PERIOD OF MVFR CONDITIONS FOR THE LATE AFTERNOON AND EARLY
EVENING. SHOULD THEN SEE JUST FLURRIES FOR THE LATE EVENING WITH
THE CEILINGS STAYING MVFR.


&&

.ARX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
MN...WINTER WEATHER ADVISORY UNTIL 6 PM CST THIS EVENING FOR MNZ086-
     094.

IA...WINTER WEATHER ADVISORY UNTIL 6 PM CST THIS EVENING FOR IAZ008-
     018-019.

&&

$$

SHORT TERM...DAS
LONG TERM...DAS
AVIATION...04



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