Area Forecast Discussion
Issued by NWS La Crosse, WI

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000
FXUS63 KARX 180520
AFDARX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
1120 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 06Z TAFS THROUGH 06Z TUESDAY NIGHT)
ISSUED AT 1120 PM CST MON NOV 17 2014

VFR CONDITIONS EXIST AT THE TAF SITES...BUT WITH RST DROPPING TO
MVFR AND EVEN IFR IN CEILING BRIEFLY BETWEEN 1-4Z...UNCERTAIN IF
CONDITIONS WILL STAY VFR OR NOT. SATELLITE AND OBSERVATION TRENDS
SUGGEST THE VFR SHOULD PERSIST THROUGH THE EARLY MORNING...THUS
HAVE CONTINUED THAT ROUTE. STILL LOOKS GOOD FOR BOTH TAF SITES TO
DROP DOWN TO MVFR AFTER 12Z IN RESPONSE TO DAYTIME HEATING AND
MOISTURE DROPPING SOUTH OUT OF NORTHERN MN. SOME FLURRIES ARE
LIKELY TOO THROUGH MUCH OF THE DAY. LATER IN THE AFTERNOON AS THE
FLOW TURNS SOUTHWESTERLY AND THE SUN BEGINS TO SET...ANTICIPATING
CEILINGS TO RISE TO VFR AND CLOUDS TO SCATTER OUT. VFR CONDITIONS
ARE THEN EXPECTED THROUGH THE EVENING AS AN ALTOSTRATUS DECK MOVES
IN AHEAD OF A SYSTEM DROPPING SOUTHEAST THROUGH MINNESOTA.

REGARDING WEST...WESTERLY WINDS IN THE 10-15 KT RANGE WILL BACK
SOUTHWEST LATE THIS AFTERNOON...THEN DIMINISH SOME IN THE EVENING
WHILE BACKING SOUTHERLY. VERY LITTLE IN THE WAY OF GUSTS ARE
EXPECTED.

&&

.ARX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
MN...NONE.
IA...NONE.
&&

$$

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



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