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000
FXUS61 KRNK 162121
AFDRNK

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BLACKSBURG VA
521 PM EDT SUN MAR 16 2014

.SYNOPSIS...
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LOW PRESSURE OVER THE LOWER MISSISSIPPI VALLEY WILL TRACK EAST
TONIGHT AND MONDAY.  A LARGE AND STRONG AREA OF HIGH PRESSURE WILL
WEDGE ALONG THE APPALACHIANS TONIGHT. ANOTHER STRONG UPPER LEVEL
DISTURBANCE WILL DART ACROSS THE GULF OF MEXICO MONDAY NIGHT ALSO
MOVING ALONG THE COAST TUESDAY. IT MAY TAKE A COLD FRONT MOVING
THROUGH OUR REGION WEDNESDAY NIGHT AND THURSDAY TO FINALLY DISLODGE
THE WEDGE.
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&&

.NEAR TERM /THROUGH MONDAY/...
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AS OF 520 PM EDT SUNDAY...

COMPLICATED FORECAST THIS AFTERNOON INTO TOMORROW WITH MARCH WINTER
STORM. THE INITIAL LOW PRESSURE CENTER OVER TENNESSEE THIS AFTERNOON
WILL WORK EAST TONIGHT AND GIVE WAY TO A COASTAL LOW TONIGHT.
DECIDED TO KEEP WINTER STORM HEADLINES WITH WARNINGS ACROSS THE
NORTH AND ADVISORIES IN THE SOUTH.

WARM ADVECTION AND ISENTROPIC LIFT ARE PUSHING PRECIPITATION SHIELD
NORTHWARD ACROSS THE FORECAST AREA THIS AFTERNOON INTO TONIGHT WITH
DRIER/COLD AIR PUSHING SOUTH. EVAPORATIVE COOLING IS OCCURRING WITH
HEAVIER RATES.  MOSTLY SNOW NORTH OF THE HWY 460 CORRIDOR WITH A
MORE MIXED NATURE NEW RIVER AND SOUTHWEST TO MOSTLY RAIN DURING THE
DAYLIGHT HOURS IN MUCH OF NORTHWEST NORTH CAROLINA. A COUPLE OF
CONCERNS WITH PRECIPITATION FOR THIS EVENING INTO TONIGHT ARE WARM
GROUND...DRY SLOT PUSHING NORTHWARD THROUGH SOUTHWESTERN NORTH
CAROLINA...CONVECTION TO SOUTH TAKING MOISTURE...MODELS HAVING HARD
TIME CAPTURING WEDGE AND TEMPERATURE PROFILES TONIGHT.

THERE IS SOME BANDING POTENTIAL ACROSS THE NORTHERN HALF CLOSER TO
THE UPPER DEFORMATION AXIS THAT WILL SET UP TONIGHT INTO MONDAY.
THIS SUPPORTS THE 6 TO 10 INCHES OF SNOW AND SLEET ACROSS THE NORTH
AND 3-6 ROA TO BUCKINGHAM WHILE HAVING A VERY SHARP CUTOFF TO THE
SOUTH WHERE MORE SLEET LIKELY AS WARMING ALOFT DEVELOPS A BIT AFTER
THE INITIAL EVAPORATIVE COOLING. ADJUSTED SNOWFALLS TOTALS ACROSS
THE SOUTHERN HALF ALLOWING FOR DRIER AIR PUSHING NORTH AND WARMER
TEMPERATURE PROFILES. SOME ICING IS POSSIBLE OVERNIGHT ALONG THE
EASTERN SLOPES WHEN THE PRECIP BECOMES LIGHTER.

DEEP MOISTURE EXITS AFTER MIDNIGHT WHILE LOW LEVEL TEMPERATURES FALL
TO BELOW FREEZING MOST SPOTS UNDER THE ENHANCED WEDGE PER LOW
PRESSURE ALONG THE COAST. THIS MAY ALLOW ICING TO DEVELOP ALONG THE
SOUTHERN BLUE RIDGE AND EVEN INTO SOUTHSIDE VA AND THE PIEDMONT OF
NORTH CAROLINA. THERE IS NOTHING GLARING IN GUIDANCE OR OBS THAT
SUGGESTS MAKING ANY CHANGES TO THE ADVISORY FOR THE SOUTH....AND
IMPACTS SHOULD BE LIMITED WITH JUST A GLAZE IN TREES AND ELEVATED
SURFACES. USED BLEND OF MOS FOR LOW TEMPERATURES TONIGHT WITH VALUES
FORM THE TEENS IN THE NORTHWEST MOUNTAINS TO THE LOWER 30S IN THE
SOUTH. FOR POPS MONDAY SHAPED TOWARDS THE GFS...AND USED TOP DOWN
WITH BLEND TEMPERATURES FOR PTYPE/WEATHER. WEDGE HOLDS TOUGH MONDAY
SO VERY CHILLY FOR MID MARCH...WITH EVEN STRONGER SUN ANGLE NOT
MAKING MUCH OF A DIURNAL FOR HIGHS.  SNOW COVER MAY ALSO HOLD
TEMPERATURES DOWN ON MONDAY. HIGH TEMPERATURES WILL RANGE FROM THE
UPPER 20S IN THE MOUNTAINS TO THE MID 30S IN THE SOUTH.
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&&

.SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY NIGHT/...
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AS OF 400 PM EDT SUNDAY...

MODELS CONTINUE TO COME INTO BETTER AGREEMENT ON THERE NOT BEING
ANOTHER ROUND OF WINTER WEATHER TUESDAY INTO WEDNESDAY AS A RESULT
OF ANOTHER COASTAL LOW DEVELOPING ALONG THE BAROCLINIC ZONE ACROSS
THE GA/SC COAST. LATEST MODEL TRENDS CONTINUE IN THE DIRECTION OF
THE EARLIER GFS RUNS SHOWING ANY COASTAL DEVELOPMENT WILL BE FURTHER
SE WITH DRIER AIR BEHIND THE CURRENT/MON SYSTEM BEING ADVECTED INTO
THE REGION FROM THE NORTHWEST. THE UPPER SUPPORT FOR THIS SYSTEM IS
ALSO FURTHER SE...ACROSS GA/FL/SC...MOVING EAST OUT TO SEA IN A
BASIC ZONAL FLOW. HOWEVER...THERE IS STILL CONCERN FOR WRAP AROUND
MARITIME MOISTURE ON NE-E SFC FLOW ON THE BACK SIDE OF THIS SYSTEM
AS IT MOVES OFF THE COAST TO RESULT IN LIGHT -DZ...ESPECIALLY ALONG
THE EAST FACING SLOPES OF THE BLUE RIDGE. WITH A COLD AIR WEDGE
REMAINING FIRMLY IN PLACE EAST OF THE APPALACHIANS...TEMPERATURES
THROUGH THE FIRST HALF OF THE DAY WILL STRUGGLE TO RISE ABOVE
FREEZING. BUT...AS NOTED...NO DYNAMICS TO GENERATE ANYTHING MORE
THAN STRATUS INDUCED -DZ. GIVEN EXPECTED SFC T...HAVE INCLUDED
-FZDZ THROUGH THE MORNING HOURS TUE IN AREAS WHERE SFC T IS 32F OR
LESS. ELSEWHERE...JUST -RA OR -DZ. ALSO MENTIONED -SN IN THE
NORTHERN AREAS...BUT THIS IS MORE OF A -SNDZ NATURE THAN DYNAMICALLY
DRIVEN -SN. POPS LESS THAN 50 PERCENT...SO NO QPF AND THUS NO SNOW
ACCUMULATION IN THE GRIDS AFT 00Z TUE.

FOR WED...A DEEP SFC/UPPER TROUGH WILL PASS THROUGH THE REGION WED
AFTERNOON. IN ADVANCE OF THIS WED MORNING...THE WEDGE REMAINS WITH
AGAIN THE POTENTIAL FOR EARLY MORNING -DZ AND EVEN A FEW POCKETS OF
-FZDZ THROUGH THE GREENBRIER AND SOUTHERN SHENANDOAH VALLEYS.
HOWEVER...BY AFTERNOON THE ASSOCIATED TROUGH WILL PASS THROUGH THE
AREA BRINGING A MODIFIED CANADIAN/PACIFIC AIR MASS INTO THE
REGION...THUS MILDER TEMPERATURES INTO THE REGION WITH 40S MOUNTAINS
AND 50S PIEDMONT. UPSLOPE -SHRA AND -SHSN TOWARD EVENING CANNOT BE
RULED OUT ACROSS EASTERN WEST VIRGINIA FAVORABLE UPSLOPE AREAS.
HOWEVER...AT THIS POINT IT APPEARS TO BE VERY INSIGNIFICANT.
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&&

.LONG TERM /THURSDAY THROUGH SUNDAY/...
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AS OF 400 PM EDT SUNDAY...

ZONAL FLOW WILL GENERALLY DOMINATE MUCH OF THE LONG RANGE PERIOD. AN
UPPER TROUGH WILL RACE THROUGH THE REGION SAT WITH A CHANCE OF
-SHRA. A SUBSTANTIAL WARMUP IS EXPECTED IN ADVANCE OF THIS SYSTEM
WITH STRONG SW FLOW. WE SHOULD SEE 60S AND PERHAPS IN A FEW LOW 70S
ACROSS THE PIEDMONT FRI IN ADVANCE OF THIS SYSTEM. DEPENDING ON THE
DEGREE OF INSTABILITY...AN ISOLD TSRA CANNOT BE COMPLETELY RULED
OUT...BUT IT HAS NOT BEEN ADVERTISED JUST YET AS THE DYNAMICS ARE
WEAK AND THE BEST INSTABILITY REMAINS EAST AND SOUTH OF THE CWA.
THIS SYSTEM HERALDS A RETURN TO COLDER NW FLOW AND A RETURN TO
NORMAL OR EVEN BELOW NORMAL TEMPERATURES FOR SUN INTO EARLY NEXT
WEEK AS A LARGE CANADIAN HIGH DROPS SOUTHEASTWARD FROM THE GREAT
PLAINS AND GREAT LAKES REGION. SOME WEAK EMBEDDED DISTURBANCES
APPEAR INEVITABLE...BUT NONE HAVE STRONG ENOUGH SIGNALS AT THIS
POINT TO INCLUDE MENTIONABLE POPS OR SIGNIFICANT UPSLOPE -SHSN. A
SOUTHERN STREAM SYSTEM AT THIS POINT IS FORECAST TO REMAIN SOUTH OF
THE CWA SUN-MON...BUT AS ALWAYS WILL NEED TO BE WATCHED CLOSELY FOR
ANY WINTER WEATHER POTENTIAL AS IT CREEPS JUST SOUTH OF OUR CWA
BORDER.
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&&

.AVIATION /21Z SUNDAY THROUGH FRIDAY/...
AS OF 1250 PM EDT SUNDAY...

VFR CLOUD BASES WILL LOWER...THEN TRANSITIONING TO MVFR THIS
AFTERNOON AND IFR CIGS BY SUNDAY AFTERNOON/EVENING. VISIBILITY
RESTRICTIONS WILL FOLLOW WITH VSBYS FALLING BLO 3SM LATER THIS
AFTERNOON AS RAIN SPREADS NORTHEAST ACROSS THE REGION.

COLD AIR ARRIVING FROM THE NORTH LATER THIS AFTERNOON INTO
TONIGHT WILL RESULT IN A CHANGE FROM RAIN TO SNOW AND SLEET FOR
ALL TERMINALS ALONG AND NORTH OF HIGHWAY 460. BASED ON LATEST
GUIDANCE...SLOWED DOWN THE ARRIVAL OF SNOW A FEW HOURS...AND SOME
IFR CIGS MAY BE EXPERIENCED SUNDAY AFTERNOON. A COMBINATION OF
SNOW AND OR DRIZZLE ALONG WITH LOW CIGS WILL THEN RESULT IN
IFR/LIFR CONDITIONS FROM SUNDAY NIGHT INTO MONDAY. WARMING AND
DRYING ALOFT MAY TRANSITION MUCH OF THE PRECIP FOR ROA/BCB/LYH TO
FREEZING DRIZZLE NEAR DAWN MONDAY...AS PRECIP SLOWS AFTER MIDNIGHT
INTO MONDAY MORNING.

LOW TO MEDIUM CONFIDENCE IN CEILINGS AND VISIBILITIES DURING THE
TAF PERIOD. MEDIUM CONFIDENCE IN WIND FORECAST.

.EXTENDED AVIATION DISCUSSION...

SUB VFR CONDITIONS WILL REMAIN IN PLAY THROUGH TUESDAY...THE
UPPER LEVEL TROUGH LINGERING POTENTIALLY INTO TUESDAY NIGHT. A
COLD FRONT IS EXPECTED TO CROSS THE AREA WEDNESDAY...SWEEPING THE
AREA FREE OF CLOUDINESS BY WEDNESDAY NIGHT. VFR CONDITIONS ARE
EXPECTED TO RETURN FOR THE 2ND HALF OF THE WORK WEEK.

&&

.RNK WATCHES/WARNINGS/ADVISORIES...
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VA...WINTER STORM WARNING UNTIL 2 PM EDT MONDAY FOR VAZ018>020-
     022>024-034-035-045>047.
     WINTER WEATHER ADVISORY UNTIL 2 PM EDT MONDAY FOR VAZ010>017-
     032-033.
     WINTER WEATHER ADVISORY UNTIL 2 PM EDT MONDAY FOR VAZ043-044-
     058-059.
NC...WINTER WEATHER ADVISORY UNTIL 2 PM EDT MONDAY FOR NCZ001-002-
     018.
     WINTER WEATHER ADVISORY UNTIL 2 PM EDT MONDAY FOR NCZ003>006-
     019-020.
WV...WINTER STORM WARNING UNTIL 2 PM EDT MONDAY FOR WVZ043>045.
     WINTER WEATHER ADVISORY UNTIL 2 PM EDT MONDAY FOR WVZ042.
-- End Changed Discussion --

&&

$$
SYNOPSIS...KK
NEAR TERM...KK
SHORT TERM...RAB
LONG TERM...RAB
AVIATION...JH/KK