-- Discussion containing changed information from previous version are highlighted. --
000
FXUS61 KRNK 112109
AFDRNK

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BLACKSBURG VA
409 PM EST WED DEC 11 2013

.SYNOPSIS...
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A DRY ARCTIC COLD FRONT WILL ARRIVE THIS EVENING. STRONG HIGH
PRESSURE LASTS THROUGH FRIDAY EVENING. AN AREA OF LOW PRESSURE
DEVELOPING NEAR THE LOWER MISSISSIPPI RIVER VALLEY FORCES
PRECIPITATION OUR WAY FOR SATURDAY...WITH AN ADDITIONAL STORM MOVING
THROUGH THE CAROLINAS SUNDAY MORNING. HIGH PRESSURE RETURNS BY
MONDAY.
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&&

.NEAR TERM /THROUGH THURSDAY/...
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AS OF 245 PM EST WEDNESDAY...

ARCTIC COLD FRONT AND STOUT UPPER LEVEL DISTURBANCE DELIVER -15C H85
AIR TO SE WEST VIRGINIA BY DAWN THURSDAY. WINDS WILL ACTUALLY
PICK UP TONIGHT...WITH SOME GUSTS TO 30 KTS POSSIBLE THROUGH THE
NEW RIVER VALLEY AND NW NC AROUND MIDNIGHT. WINDS WEAKEN SOMEWHAT
AS THE BOUNDARY RACES TO THE SOUTHEAST BY THURSDAY MORNING. TEMPS
TONIGHT MAY NOT FALL MUCH THIS EVENING WITH THE WINDS PICKING
UP...THEN FALLING OFF FAST BEHIND THE FRONT. MOISTURE IS VERY
SHALLOW AND ONLY A SMALL WINDOW OF UPSLOPE SNOW SHOWERS/FLURRIES
IS EXPECTED ACROSS THE HIGHEST ELEVATIONS OF SE WEST VA TONIGHT.
LITTLE OR NO ACCUMULATION. SURFACE HIGH PRESSURE IS CENTERED
ACROSS SW VA THURSDAY AFTERNOON WITH A COLD BUT SUNNY AFTERNOON.
REMAINING SNOWPACK ACROSS WESTERN GREENBRIER COULD KEEP THOSE
CITIES IN THE TEENS DESPITE THE SUNSHINE. SOME WARM ADVECTION
THROUGH THE DAY SHOULD ALLOW PARTS OF THE PIEDMONT/SOUTHSIDE TO
SCRAPE 40F.
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&&

.SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY NIGHT/...
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AS OF 400 PM EST WEDNESDAY...

DRY HIGH PRESSURE WILL DOMINATE THROUGH FRIDAY...BEFORE A COMPLEX
WEATHER SYSTEM MOVING NORTHEAST OUT OF THE SOUTHERN PLAINS BRINGS
MAINLY LIGHT PRECIPITATION BACK INTO THE SOUTHERN APPALACHIAN
REGION BY LATE FRIDAY NIGHT AND INTO SATURDAY. THREE MAIN
CHALLENGES WITH THIS FORECAST ARE RESULTING IN A RELATIVELY LOW
CONFIDENCE FORECAST. THE FIRST IS THE TIMING. THE LEAD SYSTEM TO
IMPACT US IS CURRENT A CLOSED LOW OFF THE COAST OF CALIFORNIA AND
WILL DEPEND ON ANOTHER SYSTEM IN THE GULF OF ALASKA TO DIG DOWN
AND KICK THIS EASTWARD. WITH BOTH THESE SYSTEMS STILL OVER THE
OCEAN...WOULD NOT EXPECT MODELS TO HAVE A VERY GOOD HANDLE ON THIS
UNTIL THURSDAY NIGHT. EXPECT A CUT OFF WOULD TEND TO BE SLOWER TO
BE EJECTED THEN MODELS GENERALLY SUGGEST...AND TRENDS HAVE BEEN A
LITTLE SLOWER...THUS WE HAVE SLOWED DOWN THE TIMING OF PRECIP
ARRIVAL UNTIL AFTER MIDNIGHT EARLY SATURDAY MORNING. ONCE IT
ARRIVES THE PRECIP MAY BE QUICK TO MOVE THROUGH...EXITING THE EAST
AS EARLY AS SATURDAY AFTERNOON...SO HAVE ACTUALLY SPED THIS TIMING
UP A BIT. OVERALL...WENT CLOSEST TO THE ECMWF TIMING ON BOTH
ENDS.

THE SECOND ISSUE IS THE AMOUNT OF PRECIPITATION. STARTING TO LOOK
LIKE BEST JET DYNAMICS WILL PASS TO THE NORTH OF OUR AREA THROUGH
THE OHIO VALLEY...WHILE CONVECTIVE ELEMENTS LIKELY TO REMAIN TO
THE SOUTH AND MAY ROB SOME OF THE MOISTURE...AND MODELS MAY BE
OVERDOING IT A BIT IN BETWEEN AS IS OFTEN THE CASE. LOOKS LIKE
PRECIP OF A HALF IN OR MORE LIKELY TO REMAIN ALONG ARE SOUTHERN
BORDER OR EVEN REMAIN TO THE SOUTH...WITH AMOUNTS DECREASING TO
PERHAPS JUST ONE OR TWO TENTHS ACROSS THE NORTH. THIS IS CLOSER TO
GFS AND ECMWF SOLUTION VS THE MUCH WETTER NAM.

FINALLY...THE THERMAL PROFILE IS THE FINAL CHALLENGE...WITH AN
ARCTIC HIGH CENTER MOVING IN FROM THE NORTHERN PLAINS TO TRY AND
REINFORCE THE EXITING HIGH THAT HAD BEEN OVER THE MID ATLANTIC
THROUGH FRIDAY. THE ECMWF IS THE STRONGEST WITH THIS HIGH AND
RESULTS IN THE BEST WEDGE NOSING BACK IN FROM THE NORTH FRIDAY
NIGHT. STILL...THE TREND HAS BEEN A LITTLE MILDER...BUT NOT AS
MILD OR STRONG WITH WARM ADVECTION THAN THE NAM AND GFS. EVEN
LEANING TOWARD THIS COLDER ECWMF SOLUTION...ITS HARD TO SEE THAT
THERMAL PROFILES WILL BE COLD ENOUGH TO SUPPORT PRECIP TO REMAIN
FROZEN FOR VERY LONG. SO STARTED WITH GFS THERMAL PROFILE AND
COOLED IT OFF A LITTLE TO CREATE THE WEATHER GRIDS...WHICH
RESULTING IN A A FEW HOURS OF LIGHT SNOW ACROSS THE FAR
NORTH...SOME SLEET FOR SOME AREAS...BUT CHANGING TO RAIN ACROSS
THE SOUTH FAIRLY QUICKLY. THINKING TOO WARM IN PIEDMONT FOR
ANYTHING BUT RAIN AT THIS POINT. AM NOT SEEING THIS AS MUCH OF A
FREEZING RAIN SCENARIO AT THIS POINT EITHER...UNLESS THE SURFACE
AIR IS EVEN COLDER THAN ECMWF IDEA...AND THE PRECIP MOVES IN WELL
BEFORE DAWN SATURDAY MORNING.

WITH MORE LIMITED PRECIP AMOUNTS AS YOU GO FARTHER NORTH...MAINLY
NORTH OF U.S.S 460...WHERE THE THERMAL PROFILES WILL REMAIN COLD
ENOUGH FOR SNOW/SLEET MIX MUCH OF THE DAY...THIS WILL LIMIT
ACCUMULATIONS TO AN INCH OR LESS. ELSEWHERE IN THE MOUNTAINS...EITHER
JUST RAIN OR A BRIEF MIX OF SLEET OR SNOW EARLY SHOULD PREVENT ANY
NOTICEABLE ACCUMULATIONS. AT LEAST THAT IS THE CURRENT
THINKING...BUT AS PREVIOUSLY MENTIONED...CONFIDENCE STILL FAIRLY
LOW FOR ALL OF THE REASONS MENTIONED ABOVE.

OVERNIGHT TEMPS FRIDAY MORNING WILL START OFF CHILLY...WITH MOSTLY
TEENS AND WENT CLOSE TO COLDER ECWMF GUIDANCE...BUT EVEN COLDER
WHERE SNOW COVER WILL STILL EXIST ACROSS FAR WESTERN SLOPES IN
SOUTHEAST WV...WITH SOME SINGLE DIGITS NOT OUT OF THE QUESTION.
WINDS NOT ESPECIALLY STRONG THURS NIGHT...AND THINK WE WILL REMAIN
ABOVE WIND CHILL ADVISORY CRITERIA.
-- End Changed Discussion --

&&

.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
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AS OF 318 PM EST WEDNESDAY...

A DEEPENING LOW PRESSURE SYSTEM OFF THE MID ATLANTIC COAST WILL
CONTINUE TO TRACK TO THE NORTHEAST AND AWAY FROM THE REGION ON
SUNDAY. A COLD FRONT WILL ALSO WORK ITS WAY TO THE EAST COAST ON
SUNDAY. NORTHWEST WINDS BEHIND THE FRONT WILL BRING COLD AIR AND
ACCUMULATING UPSLOPE SNOW SHOWERS TO WESTERN SLOPES...FLURRIES
ACROSS THE REST OF THE MOUNTAINS...INTO SUNDAY EVENING. HIGH
PRESSURE WILL THEN TRACK OVER THE OHIO VALLEY OVERNIGHT
SUNDAY...BLOCKING GREAT LAKES MOISTURE AND ENDING UPSLOPE SNOW. THE
PRESSURE GRADIENT FROM THE DEPARTING LOW TO THE NORTHEAST AND
INCOMING HIGH PRESSURE FROM THE WEST WILL BRING BREEZY/GUSTY
CONDITIONS TO THE AREA SUNDAY AND REMAIN OVER THE MOUNTAINS SUNDAY
NIGHT. WHILE THE STRONGEST PRESSURE RISES ARE OCCURRING...ENOUGH
CLOUD COVER SHOULD REMAIN TO KEEP ANY ADVISORY WINDS FROM MIXING
DOWN. HIGHEST WIND GUSTS...UP TO 40 MPH...WILL BE RESERVED FOR
ELEVATIONS ABOVE 3KFT.

THE COLD AIR DOES NOT HANGING AROUND FOR LONG. BY MONDAY
AFTERNOON...A WARM FRONT IS ALREADY PUSHING ACROSS THE OHIO VALLEY
AND WILL BRING MODERATING TEMPERATURES TO THE REGION ON TUESDAY. A
WEAK COLD FRONT MAY MOVE OVER THE APPALACHIAN ON WEDNESDAY. THIS
FRONT WILL KNOCK TEMPERATURES BACK BELOW NORMAL. WITH A DRY FRONTAL
PASSAGE...WINDY/GUSTY CONDITIONS MAY BE A CONCERN.

AN AREA OF HIGH PRESSURE WILL REMAIN ALONG THE GULF COAST FOR MOST
OF NEXT WEEK. ANY FRONTS CROSSING THE REGION NEXT WEEK MAY ONLY HAVE
ENOUGH MOISTURE TO PRODUCE CLOUDS. THE CHANCE FOR MEASURE
PRECIPITATION IS LESS THAN 10 PERCENT.
-- End Changed Discussion --
&&

.AVIATION /21Z WEDNESDAY THROUGH MONDAY/...
AS OF 1239 PM EST WEDNESDAY...

VFR WILL CONTINUE THIS AFTERNOON...WITH SOME HIGH CLOUDS AND
WINDS GUSTING TO 25 MPH AT TIMES. DRY COLD FRONT TONIGHT WILL
DELIVER POSSIBLY A PERIOD OF MVFR CIGS AT KLWB...AS UPSLOPE CLOUDS
DEVELOP IN ITS WAKE. THE ONLY OTHER IMPACT ON THE REST OF THE
TERMINALS WILL BE GUSTY WINDS. ROA/BCB MAY GUST TO 30
MPH...WHEREAS THE PIEDMONT AND SOUTHSIDE WILL EXPERIENCE WEAKER
GUSTS. GUSTS WILL WEAKEN A BIT INTO DAWN AND MORESO THROUGH
THURSDAY MORNING. PRETTY MUCH EXPECTING ANOTHER CLOUDLESS SKY ON
THURSDAY WITH POSSIBLY A 20 KT GUST IN THE AFTERNOON. WINDS WILL
SHIFT FROM WEST TO NW WITH FRONTAL PASSAGE TONIGHT AND REMAIN NW
THROUGH THURSDAY.

EXTENDED AVIATION DISCUSSION...HIGH PRESSURE CENTERED JUST TO OUR
SE FRIDAY MORNING WILL BE REPLACED BY AN AREA OF LOW PRESSURE ON
SATURDAY. SOME LIGHT FROZEN PRECIP MAY ARRIVE ACROSS SE WEST VA
AFTER MIDNIGHT FRIDAY INTO SATURDAY MORNING WITH MVFR CIGS. A
WINTRY MIX OF PRECIP EVENTUALLY CHANGING TO RAIN FOR
SATURDAY...WITH IFR CIGS/VIS POSSIBLE DEPENDING UPON THE STRENGTH
OF A COLD AIR WEDGE SATURDAY MORNING. PRECIP DEPARTS LATE SATURDAY
WITH COLDER AIR AND UPSLOPE SNOW SHOWERS FILTERING INTO LWB/BLF ON
SUNDAY WITH MVFR CIGS/VIS. GUSTY WINDS WILL BATTER THE NEW RIVER
VALLEY ONCE AGAIN LATE SATURDAY NIGHT AND EARLY SUNDAY. A MORE
TRANQUIL PATTERN RETURNS BY MONDAY WITH HIGH PRESSURE STRETCHING
FROM THE TN VALLEY INTO THE MIDDLE ATLANTIC.

&&

.RNK WATCHES/WARNINGS/ADVISORIES...
VA...NONE.
NC...NONE.
WV...NONE.

&&

$$
SYNOPSIS...KM
NEAR TERM...KM
SHORT TERM...SK
LONG TERM...RCS
AVIATION...JH/KM