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-- Discussion containing changed information from previous version are highlighted. --
000
FXUS61 KRNK 051142
AFDRNK

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BLACKSBURG VA
642 AM EST THU DEC 5 2013

.SYNOPSIS...
A SLOW MOVING COLD FRONT ENTERS THE OHIO VALLEY TODAY BEFORE
PUSHING INTO THE APPALACHIANS TONIGHT. THE BOUNDARY CRAWLS ACROSS
VIRGINIA ON FRIDAY. ARCTIC HIGH PRESSURE WELL BEHIND THE FRONT
WILL WEDGE SOUTH ALONG THE MOUNTAINS SATURDAY...BEFORE
INTERACTING WITH PRECIPITATION RETURNING NORTH BY SUNDAY.
SOUTHWESTERLY FLOW RETURNS MONDAY BEFORE A STRONGER COLD FRONT
ARRIVES LATE MONDAY NIGHT.

&&

.NEAR TERM /THROUGH TONIGHT/...
AS OF 400 AM EST THURSDAY...

ENOUGH BREAKS IN THE MID AND HIGH OVERCAST HAS ALLOWED WIDESPREAD
FOG TO FORM...DENSE AND PERSISTENT IN A FEW
LOCATIONS...ESPECIALLY ACROSS EXTREME SW VA. WILL PROBABLY ISSUE
A DENSE FOG ADVISORY AND EXPAND THE CURRENT SPS WHICH MENTIONS
AREAS OF FOG. DESPITE IMPRESSIVE H85 TEMPS NEARING +14C...CAN SEE
LOW CLOUDS PERSISTING PART OF THE DAY THROUGH THE PIEDMONT...WHICH
MAY HOLD TEMPS A FEW DEGREES BELOW GUIDANCE...LIKE YESTERDAY.
ALTHOUGH TODAY IS A BIT DIFFERENT SINCE S AND SW WINDS SHOULD
INCREASE SOMEWHAT THIS MORNING. AREA OF LIGHT SHOWERS NOW MOVING
INTO NORTH CAROLINA MAY CLIP THE SOUTHSIDE/PIEDMONT BRIEFLY AROUND
DAWN. OTHERWISE...PRECIP AND FRONT VERY SLOW TO ENTER THE CWA.
WITH THE EXCEPTION OF A PASSING SPRINKLE OR LIGHT SHOWER...TODAY
WILL BE DRY EXCEPT FOR SE WEST VA LATER TODAY. DELAYED PROGRESSION
OF POPS ANOTHER 3-6 HRS CWA WIDE. BLF LOOKS MOST PROBABLE TO
CHALLENGE ITS RECORD HIGH FOR TODAY. AN EXTREMELY WARM OVERNIGHT
WITH THE WARMER SPOTS POSSIBLY REMAINING IN THE 60S. MORE LIKELY
TONIGHT FOR FLOW UP AGAINST THE SOUTHERN BLUE RIDGE TO PRODUCE
DRIZZLE OR SHOWERS AS MOISTURE IS DEEP. HOWEVER...THE MAIN BODY OF
RAINFALL SHOULD REMAIN RESERVED TO SE WEST VA UNTIL DAYLIGHT
FRIDAY.

&&

.SHORT TERM /FRIDAY THROUGH SUNDAY NIGHT/...
AS OF 530 AM EST THURSDAY...

STRONG BAROCLINIC ZONE WILL BE THE FOCUS FOR ACTIVE WEATHER OVER THE
EASTERN CONUS THIS WEEKEND.

SURFACE COLD FRONT WILL BE ON OUR DOORSTEP TO BEGIN THE DAY
FRIDAY...EXTENDING FROM NORTHERN VIRGINIA TO EASTERN TENNESSEE...THE
LEADING EDGE OF COLDER AIR WHICH ENVELOPS MUCH OF THE CENTRAL AND
WESTERN CONUS.  THIS FRONT WILL BASICALLY BE STUCK IN PLACE FOR
ABOUT 12-18 HOURS AS AN AREA OF LOW PRESSURE DEVELOPS OVER THE
CENTRAL APPALACHIANS AND RIPPLES NORTHEAST ALONG THE FRONT.  THIS
WILL PROLONG THE UNSEASNONABLY WARM CONDITIONS ACROSS THE AREA FOR
AT LEAST THE DAYLIGHT PERIOD.  ONCE THE WAVE OF LOW PRESSURE MOVES
NORTHEAST...FRONT WILL RESUME ITS SOUTHEASTWARD PROGRESS WITH
AIRMASS CHANGE TAKING PLACE OVER OUR FORECAST AREA FRIDAY
NIGHT...TEMPERATURES TAKING ABOUT A 30 DEGREE TUMBLE.

MAIN AXIS OF RAIN SHOULD BE FOCUSED ALONG AND JUST WEST OF THE
FRONTAL BOUNDARY FRIDAY...MEANING THE BULK OF THE RAINFALL FRIDAY
WILL BE MAINLY CONFINED OUR NORTHWESTERN CWA...WEST VIRGINIA.  WITH
THE DEVELOPING WAVE OF LOW PRESSURE PRACTICALLY OVERHEAD...CAN`T
RULE OUT SOME SCATTERED SHOWERS ACROSS THE REMAINDER OF THE CWA
AIDED BY THE INSTABILITY WITHIN THE WARM SECTOR AHEAD OF THE FRONT.
CAN`T TOTALLY RULE OUT A RUMBLE OF THUNDER EITHER PER AVAILABLE
INSTABILITY...MODEL LIFTED INDICES OF M1 AND CAPES AROUND 500...BUT
WILL LEAVE OUT ALL AREAS FOR NOW.

GREATER THREAT FOR WETTING RAINFALL WILL OCCUR AS THE FRONT MOVES
ACROSS THE AREA FRIDAY NIGHT.  SUMMING UP THE 24 HOUR MODEL QPF
12Z/7AM FRIDAY THROUGH 12Z/7AM SATURDAY AND AMOUNTS ARE EXPECTED TO
RANGE FROM A THIRD OF AN INCH OVER THE NORTH CAROLINA COUNTIES...TO
AS MUCH AS AN INCH ALONG THE INTERSTATE 64 CORRIDOR ACROSS THE
NORTHERN PART OF OUR COUNTY WARNING AREA (CWA).

DESPITE CLOUDS...VERY WARM HIGH TEMPERATURES ARE IN STORE FRIDAY
WITH SOME LOW/MID 70S POSSIBLE ACROSS SOUTHSIDE VA INTO THE PIEDMONT
OF NC...AND 60S ALONG THE THE BLUE RIDGE.  TEMPERATURES WILL BE
CLOSER TO 50 VCNTY OF THE FRONT OVER SOUTHEAST WEST VIRGINIA...THE
COLDER AIR RESIDING JUST THE OTHER SIDE OF THE FRONT FROM CHARLESTON
AND POINTS NORTH AND WEST. ONCE THE FRONT MAKES ITS MOVE ACROSS THE
CWA FRIDAY NIGHT...COLD AIR ADVECTION WILL QUICKLY EAT AWAY AT THE
WARM AIRMASS...TEMPERATURES TUMBLING INTO THE 30S/40S BY
DAYBREAK SATURDAY.

MODELS ARE IN AGREEMENT THAT DRY AIR WILL WORK ITS WAY INTO THE
FORECAST AREA FROM THE NORTH SATURDAY...DEWPOINTS SLIPPING INTO THE
20S. SOME CLEARING IS POSSIBLE...ESPECIALLY ACROSS THE NORTHERN CWA
BY SATURDAY AFTERNOON.  IN SPITE OF THE PARTIAL CLEARING...
TEMPERATURES WILL STRUGGLE TO MAKE MUCH OF A RISE DUE TO THE COLD
AIR ADVECTION IN THE WAKE OF FRIDAY NIGHTS FRONTAL PASSAGE.
TEMPERATURES SATURDAY WILL REMAIN PRETTY CLOSE TO 40 IN THE
MOUNTAINS...L-MID 40S EAST OF THE BLUE RIDGE.

BAROCLINIC ZONE WILL BECOME THE FOCUS FOR MORE ACTIVE WEATHER FOR
THE SECOND HALF OF THE WEEKEND.  THIS TIME WE WILL BE ON THE COLD
SIDE OF THE FRONT WHICH WILL BE STALLED ACROSS THE CAROLINAS JUST TO
OUR SOUTH.  MODELS HAVE BEEN CONSISTENT WITH YET ANOTHER WAVE OF LOW
PRESSURE WHICH WILL RIPPLE NORTHEAST ALONG THE BAROCLINIC ZONE. THIS
WILL CAST DEEPER MOISTURE BACK ACROSS THE FORECAST AREA LATE
SATURDAY NIGHT AND SUNDAY FOR ANOTHER ROUND OF PRECIPITATION...QPF
OF A QUARTER TO A HALF INCH ENDING 18Z/1PM SUNDAY.  PROBLEM THIS GO
ROUND WILL BE THE TEMPERATURE PROFILE. CLASSIC COLD AIR DAMMING SET
UP IS ADVERTISED WITH A 1037 MB SURFACE HIGH TO OUR NORTH AND A WAVE
OF LOW PRESSURE OVERRUNNING THE COLDER AIRMASS. COLD SUBFREEZING
BOUNDARY LAYER...2-4KFT THICK...IS FORECAST TO BE CAPPED BY WARM
ABOVE FREEZING LAYER ALOFT.  THIS SUGGESTS P-TYPE FOR MOST OF OUR
CWA WILL BE FREEZING RAIN.  WARM LAYER WILL BE SHALLOWEST NORTH OF
INTERSTATE 64...SO PRECIP COULD BE MIXED WITH SLEET AND OR SNOW THE
FARTHER NORTH YOU RESIDE IN THE COLDER AIR.

FOR NOW WILL PLACE PRIMARY FOCUS ON THE FREEZING RAIN...HAVING THE
HIGHEST CONFIDENCE FOR THIS PARTICULAR P-TYPE WITHIN THIS SORT OF
PATTERN. BASED ON CLIMATOLOGY FOR THESE SORT OF EVENTS...GREATEST
ICING THREAT IS EXPECTED ALONG THE BLUE RIDGE AND FROM THE
GREENBRIER AND NEW RIVER VALLEYS...NORTHEAST INTO THE ROANOKE AND
SHENANDOAH VALLEYS...INCLUDING LYNCHBURG AND VICINITY.

TEMPERATURES SUNDAY WILL RISE VERY LITTLE IF ANY. WARMER AIR ALOFT
MAY WORK ITS WAY TO THE SURFACE ACROSS THE FAR WESTERN CWA...BUT
HERE ON THE EAST SIDE OF THE APPALACHIANS...HIGH PRESSURE TO OUR
NORTH WILL REINFORCE THE COLD AIR PER CONTINUATION OF A COLD
NORTHEASTERLY SURFACE WIND.

WARMER AIR IS ADVERTISED TO EVENTUALLY WIN OUT LATE SUNDAY NIGHT
INTO MONDAY.

&&

.LONG TERM /MONDAY THROUGH WEDNESDAY/...
AS OF 600 AM EST THURSDAY...

WARMER AIR WILL CONTINUE TO WORK IN FROM THE SOUTHWEST LATE SUNDAY
NIGHT AND MONDAY MORNING...WITH THE LAST POCKETS OF FREEZING RAIN
ACROSS THE ALLEGHANY HIGHLANDS AND SHENANDOAH VALLEY ENDING BY
SUNRISE MONDAY. WARM AIR ADVECTION WILL BRING TEMPERATURES ABOVE
FREEZING AREAWIDE MONDAY...PRIOR TO ANOTHER COLD FRONTAL PASSAGE
MONDAY AFTERNOON.

THE COLD FRONT MAY STALL ALONG THE COAST MONDAY NIGHT AND TUESDAY
MORNING AS MODELS HINT AT YET ANOTHER WAVE DEVELOPING ALONG THE
BOUNDARY. IF THIS OCCURS IT WILL DELAY THE CLEARING PROCESS UNTIL
TUESDAY. BY TUESDAY AFTERNOON...THE FRONT WILL CONTINUE ITS EASTWARD
PUSH...ENDING PRECIPITATION ACROSS OUR AREA AND BRINGING A RETURN OF
DRY HIGH PRESSURE FROM THE WEST. UPPER LEVEL TROUGHING ACROSS THE
NORTHEAST WILL KEEP TEMPERATURES ON THE COOL SIDE DURING THE MIDDLE
OF NEXT WEEK.

&&

.AVIATION /12Z THURSDAY THROUGH MONDAY/...
-- Changed Discussion --
AS OF 700 AM EST THURSDAY...

STRONG COLD FRONT WILL BE APPROACHING FROMT THE OHIO VALLEY
TODAY...STALLING ALONG THE SPINE OF THE APPALACHIAN MOUNTAINS
TONIGHT.

STRATUS/FOG RESULTED IN LOW IFR CIGS/VSBYS EARLY THIS MORNING
ALONG AND EAST OF THE BLUE RIDGE. GRADUAL IMPROVEMENT IS EXPECTED
AFTER MID MORNING...TRENDING FROM MVFR TO VFR THIS AFTERNOON.
SURFACE WINDS WILL BECOME SOUTH TO SOUTHWEST ON THIS AFTERNOON
WITH MODERATE TO HIGH CONFIDENCE THAT TAFS SITES WILL IMPROVE TO
VFR BY 18Z/1PM. AFTER SUNSET...CLOUD BASES WILL LOWER BACK INTO
THE MVFR CATEGORY.

EXTENDED AVIATION CONCERNS...A COLD FRONT WILL MAKE SLOW PROGRESS
ACROSS THE AREA FRIDAY...RESULTING IN MVFR AND IFR CONDITIONS IN
ADDITION TO WIDESPREAD RAIN SHOWERS...BEFORE THE FRONT PASSES EAST
FRIDAY NIGHT. MAY SEE A BRIEF IMPROVEMENT TO VFR ON SATURDAY AS
HIGH PRESSURE BUILDS IN FROM THE NORTH...HOWEVER IFR WILL RETURN
SATURDAY NIGHT AS ANOTHER SYSTEM APPROACHES FROM THE
SOUTHWEST...BRINGING FREEZING RAIN TO THE AREA SUNDAY.  A COLD
FRONT WILL MOVE THROUGH ON MONDAY...BRINGING A SLOW IMPROVEMENT TO
VFR AFTER ITS PASSAGE FOR TUESDAY.

HIGH PRESSURE IS EXPECTED TO PROVIDE FAIR WEATHER WITH VFR
CONDITIONS FROM TUESDAY THROUGH THURSDAY.
-- End Changed Discussion --

&&

.CLIMATE...
WARM TEMPERATURES THE NEXT COUPLE DAYS WILL APPROACH RECORDS AT THE
CLIMATE SITES. BELOW ARE THE CURRENT RECORDS.

DECEMBER 5 CURRENT RECORD HIGH TEMPERATURES (YEAR)

ROA76(2001)
LYH76(2001)
DAN 75(1982)
BCB70(2001)
BLF71(2001)
LWB68(2001)

DECEMBER 5 CURRENT RECORD HIGH MINIMUM TEMPERATURES (YEAR)

ROA58(1982)
LYH60(1982)
DAN57(1982)
BCB52(1982)
BLF55(1994)
LWB53(1994)

DECEMBER 6 CURRENT RECORD HIGH MINIMUM TEMPERATURES (YEAR)

ROA52(2011)
LYH52(2011)
DAN60(2011)
BCB51(2011)
BLF56(2011)
LWB 52  (1998)

&&

.RNK WATCHES/WARNINGS/ADVISORIES...
VA...DENSE FOG ADVISORY UNTIL 8 AM EST THIS MORNING FOR VAZ009-012-
     015>017-032.
NC...DENSE FOG ADVISORY UNTIL 8 AM EST THIS MORNING FOR NCZ001>004-
     018>020.
WV...NONE.

&&

$$
SYNOPSIS...JH/KM
NEAR TERM...KM
SHORT TERM...PM
LONG TERM...NF
AVIATION...PM
CLIMATE...CF