Area Forecast Discussion
Issued by NWS La Crosse, WI

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000
FXUS63 KARX 172339
AFDARX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
539 PM CST MON NOV 17 2014

.SHORT TERM...(THIS EVENING THROUGH TUESDAY)
ISSUED AT 143 PM CST MON NOV 17 2014

CHALLENGES INCLUDE LINGERING LIGHT SNOW SHOWERS/FLURRIES AND
BLOWING SNOW THIS EVENING...FOLLOWED BY LIGHT ACCUMULATING SNOW
TUESDAY NIGHT INTO WEDNESDAY MORNING AND THEN UNSEASONABLE COLD
CONTINUING THROUGH FRIDAY. 17.12Z GLOBAL MODELS ARE IN GOOD
AGREEMENT THROUGH 22.00Z (FRIDAY NIGHT)...DIVERGING INTO THE
WEEKEND WITH THE TRACK AND EVOLUTION OF A STRONG EAST-PACIFIC
WAVE AS IT EJECTS FROM THE SOUTHERN PLAINS INTO THE UPPER
MIDWEST.

FOR TONIGHT...LIGHT SNOW SHOWERS/FLURRIES IN COLD CYCLONIC FLOW
ALOFT WILL DISSIPATE BY MIDNIGHT WITH NO MORE THAN A COUPLE TENTHS
OF ACCUMULATION. BLOWING/DRIFTING SNOW ALSO EXPECTED TO SUBSIDE
AFTER SUNSET. WITH ARCTIC AIR MASS FULLY IN PLACE AND AFTERNOON
HIGHS TODAY ONLY REACHING THE MID TEENS...EXPECT LOWS TO EASILY
DROP INTO THE SINGLE DIGITS ABOVE ZERO AND EVEN FAVORED COLD SPOTS
A FEW DEGREES BELOW ZERO. 17.18Z RAP SHOWS 0.5 KM WINDS OVERNIGHT
AROUND 30 KTS WITH A NEARLY DRY ADIABATIC BOUNDARY LAYER TO THIS
LEVEL...SO EXPECT A BREEZY NIGHT WITH WESTERLY WINDS FROM 10 TO 15
MPH. THIS WILL RESULT IN WIND CHILL VALUES BY TUESDAY MORNING FROM
10 TO 20 BELOW ZERO. THE REST OF TUESDAY WILL BE MOSTLY CLOUDY BUT
DRY AND BREEZY WITH AFTERNOON HIGHS SIMILAR TO TODAY.

.LONG TERM...(TUESDAY NIGHT THROUGH MONDAY)
ISSUED AT 143 PM CST MON NOV 17 2014

THE NEXT SHORT-WAVE ALOFT ROTATES THROUGH THE UPPER MISSISSIPPI
RIVER VALLEY TUESDAY NIGHT. 850 TO 600 HPA FORCING INCREASES
ALONG WARM FRONTAL BOUNDARY AND WITH AROUND 4 UBAR/S OF OMEGA
CENTERED ALONG THE DENDRITIC GROWTH ZONE...EXPECT A QUICK ONE INCH
OR LESS OF ACCUMULATION MAINLY ALONG AND EAST OF THE MISSISSIPPI
RIVER. INCREASED POPS INTO THE LIKELY CATEGORY TUESDAY NIGHT FOR
THESE AREAS. TEMPERATURES TUESDAY NIGHT WILL DROP INTO THE SINGLE
DIGITS TO LOW TEENS ABOVE ZERO.

REINFORCING COLD FRONT SWINGS ACROSS THE REGION EARLY WEDNESDAY
MORNING...KEEPING DAILY TEMPERATURES WELL BELOW SEASONAL NORMALS
THROUGH THE REST OF THE WORK WEEK. EXPECT HIGHS IN THE TEENS AND
20S AND LOWS IN THE SINGLE DIGITS AND LOW TEENS. WEDNESDAY THROUGH
FRIDAY WILL BE DRY...HOWEVER...WITH SURFACE HIGH PRESSURE MOVING
ACROSS THE NATION/S MID-SECTION. BREEZY WEST-NORTHWEST WINDS
WEDNESDAY AND THURSDAY WILL BECOME LIGHT THURSDAY NIGHT INTO
FRIDAY AS CENTER OF SURFACE HIGH SLIDES ACROSS IOWA AND PRESSURE
GRADIENT WEAKENS.

SATURDAY THROUGH MONDAY...17.12Z GFS/ECMWF IN AGREEMENT THAT AN
OPEN WAVE WILL MOVE INTO THE UPPER MIDWEST FROM THE SOUTHERN
PLAINS. GFS IS QUICKER AND FARTHER EAST WITH SURFACE LOW TRACK
COMPARED TO THE ECMWF AND THUS LESS ROBUST WITH PRECIP ACROSS THE
FORECAST AREA. THE ECMWF...HOWEVER...DEPICTS 0.75 TO 1.5 INCHES OF
LIQUID PRECIP THROUGH MONDAY AS IT DRAGS A SLOW-MOVING DEFORMATION
PRECIP ZONE ACROSS THE AREA. BOTH MODELS WARM ENOUGH FOR ANY
PRECIP TO INITIALLY FALL AS RAIN ON SATURDAY/SUNDAY AND EVENTUALLY
CHANGING OVER TO SNOW SUNDAY NIGHT INTO MONDAY. CONFIDENCE HIGH
ENOUGH TO INCREASE POPS INTO THE HIGH CHANCE CATEGORY...BUT STILL
LOTS OF DETAILS TO SORT OUT.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z TUESDAY EVENING)
ISSUED AT 539 PM CST MON NOV 17 2014

SIMILAR TO LAST EVENING...LOSS OF DAYTIME HEATING HAS ALLOWED EITHER
CEILINGS TO RISE OR SKIES TO FLAT OUT CLEAR. THIS HAS OCCURRED
ACROSS MUCH OF THE UPPER MIDWEST. THEREFORE...HAVE TRENDED THE TAF
FORECASTS MORE OPTIMISTIC WITH VFR CONDITIONS FOR MUCH OF
TONIGHT. STILL KEPT A BRIEF PERIOD OF MVFR IN VISIBILITY AND
CEILING AT RST AS A BAND OF -SN NEAR I-35 COULD IMPACT THE TAF
SITE BEFORE FALLING APART. WITH CYCLONIC FLOW IN PLACE TUESDAY
MORNING...ONSET OF DAYTIME HEATING SHOULD ALLOW MVFR CEILINGS TO
FORM. CANNOT RULE OUT SOME FLURRIES AS WELL FALLING FROM THESE
CLOUDS. LATER IN THE AFTERNOON...COMBINATION OF LOSS OF DAYTIME
HEATING AND FLOW TURNING MORE SOUTHWESTERLY SHOULD HELP TO IMPROVE
CONDITIONS BACK TO VFR.

REGARDING WINDS...THE BLUSTERY NORTHWEST WINDS ARE DIMINISHING...
AT LEAST THE GUSTS...DUE TO THE LOSS OF DAYTIME HEATING.
STILL...AROUND A 15 KT BREEZE SHOULD PERSIST THROUGH MUCH OF THE
NIGHT WHILE BACKING WESTERLY. MUCH OF TUESDAY SHOULD FEATURE A
10-15 KT WIND...TURNING SOUTHWESTERLY LATE...WITH LITTLE IN THE
WAY OF GUSTINESS.

&&

.ARX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
MN...WINTER WEATHER ADVISORY UNTIL 6 PM CST THIS EVENING FOR MNZ086-
     087-094-095.

IA...WINTER WEATHER ADVISORY UNTIL 6 PM CST THIS EVENING FOR IAZ008-
     009-018-019.

&&

$$

SHORT TERM...ROGERS
LONG TERM...ROGERS
AVIATION...AJ



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