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-- Discussion containing changed information from previous version are highlighted. --
000
FXUS61 KRNK 041018
AFDRNK

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BLACKSBURG VA
518 AM EST WED DEC 4 2013

.SYNOPSIS...
SURFACE HIGH OFF THE MIDDLE ATLANTIC SEABOARD DRIFTS EAST AS A
WARM FRONT PUSHES INTO SOUTHWESTERN VIRGINIA TODAY. A STRONG BUT
SLOWING COLD FRONT MOVES INTO THE OHIO VALLEY TONIGHT. THIS
BOUNDARY STALLS ALONG THE APPALACHIANS THURSDAY BEFORE CRAWLING
ACROSS VIRGINIA ON FRIDAY. SATURDAY`S SURFACE HIGH WILL INTERACT
WITH AN UPPER LEVEL TROUGH BY SUNDAY.

&&

.NEAR TERM /THROUGH TONIGHT/...
AS OF 337 AM EST WEDNESDAY...

SOME REMAINING EASTERLY COMPONENT...NOT REALLY A WEDGE...WILL TRY
TO HOLD OFF STRONG WAA FROM THE SOUTHWEST TODAY. ATTM...SOLID
AREA OF SHOWERS ASSOC WITH CENTER OF UPPER LEVEL DISTURBANCE AND
GOOD H7 RH ACROSS THE SOUTHSIDE AND PIEDMONT...WILL END BY
SUNRISE. LOW CLOUDS ACROSS THE ENTIRE CWA WITH THE EXCEPTION OF
EXTREME SE WEST VA/SW VA WITH BLF/JFZ DEALING WITH MID AND HIGH
CLOUDS ONLY. LOW CLOUDS WILL PERSIST THROUGH THE MORNING...BUT
WITH WAA BEGINNING TO WIN OUT GREATER MIXING SHOULD ALLOW FOR SOME
IMPROVEMENT BY THIS AFTERNOON WITH SOME SUN. DESPITE THE CLOUDS
AND THE EASTERLY COMPONENT...H85 TEMPS 2-4C WARMER THAN YESTERDAY
SHOULD NUDGE HIGH TEMPS AT LEAST A DEGREE OR TWO WARMER THAN
TUESDAY. THE AFOREMENTIONED EXTREME SE WEST VA/SW VA SHOULD ARRIVE
AT THE WARMER MET MOS NUMBERS WITH LESS LOW CLOUD AND MORE SUNNY
BREAKS WHERE THE MIDDLE 60S MAY BE ATTAINABLE.

ONLY A BRIEF DRYING OF THE LLVLS THIS AFTERNOON...AS TEMPS ONLY
HAVE TO COOL SLIGHTLY FOR CLOUDS TO REFORM THIS EVENING. VERY
MOIST AND SOMEWHAT STRONGER SOUTHERLY FLOW INTO THE SOUTHERN BLUE
RIDGE AND NW NC TONIGHT AHEAD OF THE SLOW MOVING COLD
FRONT...SHOULD ALLOW DRIZZLE/RAIN/FOG TO FORM AND BECOME MORE
WIDESPREAD THAN THIS PAST EVENING. ALSO MORE BREEZE AND CLOUDS
WITH H85 TEMPS NEAR +10C MEANS A BALMY OVERNIGHT TO SAY THE LEAST.
MANY SPOTS WILL STAY IN THE 50S EVEN WELL AFTER MIDNIGHT.

&&

.SHORT TERM /THURSDAY THROUGH SATURDAY/...
-- Changed Discussion --
AS OF 430 AM EST WEDNESDAY...

BUSY WEATHER PATTERN FOR THE LATER HALF OF THE WEEK AND THROUGH
THE UPCOMING WEEKEND.

SYNOPTIC PATTERN FEATURES A DEEP WESTERN TROUGH AND BUILDING
SOUTHEASTERN U.S. RIDGE WITH ARCTIC AIR DOMINATING MUCH OF THE
WESTERN CONUS WHILE SOUTHERLY FLOW BRINGS VERY MILD AIR NORTHWARD
INTO THE MID ATLANTIC STATES. THIS FLOW PATTERN YIELDS HIGH
CONFIDENCE FOR ABOVE NORMAL TEMPERATURES THURSDAY AND INTO THE DAY
FRIDAY. TEMPERATURES THURSDAY MORNING MAY TEST RECORD HIGHS MINS IN
THE MORNING WITH LOW UPPER 40S TO MID 50S AND RUNNING CLOSE TO 20F
ABOVE NORMAL. DEPENDING ON AMOUNT OF CLOUDS DURING THE DAY COULD
APPROACH RECORD HIGHS ON THURSDAY AS H85 TEMPS CLIMB INTO +12 TO
+14C RANGE AND WITH CURRENT GRIDS CARRYING MID-60S TO LOW 70S WHICH
ARE IN THE BALLPARK OF RECORDS BUT GENERALLY 2 TO 4F BELOW EXISTING
RECORDS. A FEW WELL-PLACED HOURS OF SUN COULD CAUSE BUST POTENTIAL
ON THE UPSIDE.

CLASH BETWEEN THE AIRMASSES WILL BE IN THE FORM OF AN ARCTIC FRONT
WHICH IS FORECAST TO BISECT THE CONUS FROM THE GREAT LAKES TO TEXAS
ON THURSDAY. PRIMARY AREA OF LOW PRESSURE THURSDAY IS EXPECTED TO BE
CENTERED OVER LAKE SUPERIOR. A LARGE 1040+ MB ARCTIC HIGH WILL BE
DROPPING SOUTHEAST FROM THE INTERMOUNTAIN WEST WITH COLD AIR FLOWING
SOUTH AND EAST ACROSS THE PLAINS AND INFILTRATING AREAS FARTHER EAST
BEHIND THE EAST BOUND ARCTIC FRONT.  THE FRONT IS EXPECTED TO REACH
THE APPALACHIAN MOUNTAINS THURSDAY NIGHT...BUT THEN STALL AS A NEW
WAVE OF LOW PRESSURE DEVELOPS OVER THE SOUTHERN APPALACHIANS AND
RIPPLES NORTHEAST ALONG THE FRONT FRIDAY AND FRIDAY NIGHT.  THIS
WILL LIKELY DELAY THE TRANSITION TO COLD AIR ACROSS OUR REGION
UNTIL FRIDAY NIGHT FOLLOWING THE PASSAGE OF THE AREA OF LOW
PRESSURE.   H85 TEMPS START OUT NEAR 15C IN THE EAST EARLY FRIDAY
AND RECORD HIGH MINS ARE EVEN A BETTER POSSIBILITY WITH MORNING LOWS
NO LOWER THAN 60 EAST OF THE MOUNTAINS. FRIDAYS HIGHS COULD EASILY
CLIMB INTO THE L70S ACROSS SOUTHSIDE VA AND INTO THE PIEDMONT OF
NC...ANOTHER +20 DEG ABOVE NORMAL DAY.  SUB-ZERO H85 AIR FINALLY
REACHES THE NW ZONES AROUND MIDNIGHT FRIDAY NIGHT...THE COLD AIR
THEN INFILTRATING THE REMAINDER OF THE CWA AFTER MIDNIGHT.

HIGH CONFIDENCE FOR WETTING RAINFALL WITH THE FRONTAL PASSAGE AND
ASSOCIATED WITH THE WAVE OF LOW PRESSURE FRIDAY AND FRIDAY NIGHT.
QPF IN THE FORM OF RAINFALL THROUGH FRIDAY NIGHT WILL BE ON THE
ORDER OF A HALF /0.50/ TO ONE INCH /1.00/.

SATURDAY WILL FEATURE A TRANSITION TO MUCH COLDER TEMPERATURES
ACROSS THE FORECAST AREA...TEMPERATURES ACTUALLY TRENDING BACK
CLOSER TO DECEMBER NORMALS.  WARMEST TEMPERATURES SATURDAY WILL
OCCUR AROUND MIDNIGHT FRIDAY NIGHT...STEADILY FALLING THROUGH THE
DAY SATURDAY AS COLD AIR ADVECTION PREVAILS.  ANY PRECIP SATURDAY
WILL BE MAINLY CONFINED TO THE CAROLINAS WHERE THE FRONT IS
EXPECTED TO STALL DUE TO YET ANOTHER WAVE OF LOW PRESSURE WHICH WILL
BE FORMING ALONG THE FRONT. NO P-TYPE ISSUES ARE EXPECTED DURING THE
DAYLIGHT HOURS SATURDAY.
-- End Changed Discussion --

&&


.LONG TERM /SATURDAY NIGHT THROUGH TUESDAY/...
-- Changed Discussion --
AS OF 500 AM EST WEDNESDAY...

POTENTIAL FOR A FREEZING RAIN SCENARIO IS INCREASING FOR THE AREA
SATURDAY NIGHT AND INTO THE DAY SUNDAY.

STALLED FRONT TO OUR SOUTH SATURDAY NIGHT WILL BECOME THE FOCUS FOR
ANOTHER SURGE OF MOISTURE TO MOVE NORTHWARD ACROSS THE AREA SATURDAY
NIGHT AND SUNDAY. ANOTHER WAVE OF LOW PRESSURE IS EXPECTED TO FORM
OVER THE SOUTHERN APPALACHIANS AND RIPPLE NORTHEAST ALONG THE FRONT.
THIS WILL PRODUCE ANOTHER ROUND OF RAINFALL...QPF OF A QUARTER
/0.25/ TO A HALF /0.50/ INCH...ACROSS OUR FORECAST AREA. WITH A 1037
MB SURFACE HIGH CENTERED OVER NEW YORK STATE AND WEDGED DOWN THE
EAST SIDE OF THE APPALACHIANS...THIS ROUND OF RAINFALL WILL NOT BE
ALL LIQUID. MODELS...BOTH THE GFS AND ECMWF...ARE IN BASIC AGREEMENT
THAT ENOUGH COLD AIR WILL HAVE INFILTRATED THE FORECAST AREA
SATURDAY NIGHT ASSOCIATED WITH THE COLD AREA OF HIGH PRESSURE TO OUR
NORTH TO SUPPORT FREEZING PRECIPITATION AT THE SURFACE...TEMPS
DIPPING INTO THE U20S/L30S SATURDAY NIGHT.  ALOFT...TEMPERATURES ARE
FORECAST TO REMAIN ABOVE FREEZING.  AS SUCH...THINK THE PRIMARY
CONCERN SUNDAY MORNING WILL BE FREEZING RAIN.

WILL CONTINUE TO ADVERTISE FREEZING RAIN THREAT FOR FOR PORTIONS OF
THE MOUNTAINS AND THE PIEDMONT NORTH OF INTERSTATE 81 SATURDAY NIGHT
INTO LATE SUNDAY MORNING.  MAY NEED TO EXPAND THIS AREA OF CONCERN
PENDING FUTURE FORECAST TEMPERATURE GUIDANCE. ATTM THINK AREAS SOUTH
OF INTERSTATE 81 WILL NUDGE JUST ABOVE FREEZING SUNDAY
AFTERNOON...BUT DO NOT SEE THIS OCCURRING FARTHER NORTH...WHERE
AFTERNOON HIGHS ARE EXPECTED TO REMAIN AT OR BELOW FREEZING.  THIS
SUGGESTS WE MAY BE LOOKING AT A PROLONGED FREEZING RAIN EVENT INTO
EARLY MONDAY FOR AREAS FROM THE GREENBRIER VALLEY THROUGH THE
SHENANDOAH VALLEY.

BY LATE MONDAY MORNING...WILL SEE WINDS SHIFT MORE SOUTHWESTERLY AS
THE HIGH PRESSURE WEDGE FINALLY ERODES...JUST BEFORE OUR NEXT COLD
FRONT PUSHES THROUGH THE AREA. THE GFS MODEL IS SLIGHTLY FASTER IN
THE TIMING OF THE NEXT FRONT COMPARED TO THE ECMWF...BUT BOTH MODELS
AGREE THAT THE FRONT WILL SHIFT THROUGH DURING THE DAY. WILL LIKELY
SEE ANOTHER ROUND OF SHOWERS ASSOCIATED WITH THE FRONT...A WET START
TO THE WORK WEEK. AFTER MONDAY...TEMPERATURES TAKE A TUMBLE...THE 8
TO 14 DAY OUTLOOK FEATURING TEMPERATURES BELOW NORMAL.
-- End Changed Discussion --

&&

.AVIATION /10Z WEDNESDAY THROUGH SUNDAY/...
AS OF 1135 PM EST TUESDAY...

LATEST SURFACE OBSERVATIONS INDICATE HIGH PRESSURE OFF THE OUTER
BANKS THIS EVENING...WITH LOW PRESSURE TO OUR WEST...RESULTING IN
A LIGHT SOUTHEAST SURFACE AND LOW LEVEL WINDS. MOST CEILINGS WILL
CONTINUE TO LOWER OVERNIGHT AS MOISTURE CONTINUES TO FILTER INTO
THE REGION. HIGH CONFIDENCE OF IFR CEILINGS AT KBCB...KROA...KDAN
BETWEEN 06Z/1AM AND 12Z/7AM.

KEEPING CEILINGS MOSTLY MVFR INTO LATE MORNING...BEFORE AFTERNOON
HEATING ALLOWS FOR BREAKS IN THE LOWER CLOUD COVER. WITH THE
UPSLOPE FLOW.

EXTENDED AVIATION CONCERNS...A STRONG COLD FRONT WILL APPROACH
THE MID ATLANTIC REGION THURSDAY...CROSSING THE AREA LATE FRIDAY
AND SATURDAY. SOUTH WINDS WILL INCREASE AHEAD OF THIS FRONT
THURSDAY WITH A WIND SHIFT TO THE WEST FRIDAY...AND TRENDING
NORTH FOR THE WEEKEND. RAIN WILL ACCOMPANY THE FRONT FRIDAY AND
SATURDAY WITH MVFR/IFR CONDITIONS LIKELY.

NORTH WINDS SATURDAY WILL RESULT IN FALLING TEMPERATURES WITH
POTENTIAL FOR FREEZING RAIN AND ICING CONDITIONS SATURDAY NIGHT
AND SUNDAY...ESPCLY FOR TERMINALS NEAR AND WEST OF THE BLUE RIDGE.

&&

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

&&

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