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[Printable]
307
FXUS61 KRNK 221429
AFDRNK

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BLACKSBURG VA
1029 AM EDT WED OCT 22 2014

.SYNOPSIS...
LOW PRESSURE OFF THE DELMARVA COAST THIS MORNING WILL STRENGTHEN
INTO A NOR-EASTER THAT WILL PELT NEW ENGLAND WITH HEAVY RAINFALL.
BACKLASH FROM THIS SYSTEM WILL BE FELT ACROSS OUR REGION THROUGH
THURSDAY IN THE FORM OF CONSIDERABLY CLOUDY COOL WEATHER ALONG WITH
GUSTY NORTHWEST WINDS. A MODERATING TREND WILL OCCUR OVER THE
WEEKEND AS THE STORM SYSTEM MOVES AWAY FROM THE AREA...REPLACED BY
HIGH PRESSURE THAT WILL BRING WARMING CONDITIONS FOR THE
WEEKEND...AND ABOVE NORMAL TEMPERATURES FOR THE LAST WEEK OF OCTOBER.

&&

.NEAR TERM /THROUGH TONIGHT/...
AS OF 1020 AM EDT WEDNESDAY...

REGIONAL RADARS SHOW SHOWERS ROTATING AROUND DEVELOPING SURFACE LOW
PRESSURE ALONG THE MIDDLE ATLANTIC COAST. EXPECTATION IS THAT THIS
ACTIVITY WILL CONTINUE TO BRUSH OUR FAR EASTERN ZONES THROUGH EARLY
THIS AFTERNOON UNTIL ACTIVITY PULLS A BIT EASTWARD. WILL ADJUST
POPS TO KEEP THE CHANCE OF SHOWERS INTO EARLY THIS AFTERNOON. THE
OTHER AREA WITH PRECIPITATION TO DEAL WITH WILL BE IN THE FAR WEST
WHERE UPSLOPE FLOW WILL CONTINUE TO SQUEEZE OUT SOME SPRINKLES
TODAY. FOR THE REST OF THE AREA IN BETWEEN...IT LOOKS LIKE A FAIR
AMOUNT OF SUN IN DOWNSLOPE FLOW.

AS THE LOW ALONG THE COAST CONTINUES TO STRENGTHEN...THE WINDS
WILL RESPOND TO THE TIGHTENING PRESSURE GRADIENT AND WE CAN EXPECT
GUSTY CONDITIONS TO PREVAIL...ESPECIALLY FOR AREAS ALONG THE BLUE
RIDGE.

.PREVIOUS AFD...

THE GREATER INFLUENCE FOR OUR REGION SHOULD BE THE WIND. 85H
WINDS ARE PROGGED AROUND 40 KTS FROM THE NORTHWEST TODAY. THIS
WILL TRANSLATE INTO BREEZY CONDITIONS AT THE SURFACE WITH WIND
GUSTS OF 20 TO 30 MPH...AND 30 TO 35 MPH IN THE HIGHER ELEVATIONS.
AN ISOLATED HIGHER GUST MAY BE POSSIBLE ACROSS THE HIGHEST
TERRAIN. EXPECTED WINDS TO REMAIN BELOW WIND ADVISORY LEVELS. 6
HOUR PRESSURE CHANGES THIS MORNING WERE GENERALLY 2 TO 3 MB THEN
DECREASE THIS AFTERNOON INTO TONIGHT. TEMPERATURES TODAY WILL
RANGE FROM THE MID 40S IN THE NORTHWEST MOUNTAINS TO THE LOWER 60S
IN THE PIEDMONT...CLOUD COVER AND LOWERING THICKNESSES FROM THE
DEVELOPING CYCLONE PUTTING A DAMPER ON ANY CONTRIBUTION FROM SOLAR
INSOLATION.

AS AN OCCLUDED LOW/NOR-EASTER DRIFT OFF THE MID ATLANTIC COAST
TONIGHT INTO THURSDAY....SHORTWAVES WILL PIVOT AROUND THIS LOW AND
TRACK OVER THE FORECAST AREA. KEPT THE HIGHEST POPS ACROSS THE NORTH
ESPECIALLY ACROSS THE GREENBRIER VALLEY AND ALLEGHANY HIGHLANDS.
TEMPERATURES WILL DROP ENOUGH IN THE HIGHEST ELEVATIONS FOR A RAIN
AND SNOW MIXTURE TO BE POSSIBLE LATE TONIGHT INTO THURSDAY MORNING.
NO SNOW ACCUMULATIONS EXPECTED. LOW TEMPERATURES TONIGHT WILL RANGE
FROM THE MID 30S IN THE MOUNTAINS TO THE LOWER 40S IN THE PIEDMONT.

&&

.SHORT TERM /THURSDAY THROUGH SATURDAY NIGHT/...
AS OF 400 AM EDT WEDNESDAY...

WINDS WILL REMAIN ON THE GUSTY SIDE FROM THE NORTHWEST ON THURSDAY
AS A TIGHTENED PRESSURE GRADIENT REMAINS IN PLACE BETWEEN DEEPENING
LOW PRESSURE OFF THE NEW ENGLAND COAST...AND HIGH PRESSURE BUILDING
EAST ACROSS THE OHIO RIVER VALLEY. THE NORTHWESTERLY FLOW WILL
MAINTAIN A FEW RAIN SHOWERS ACROSS SOUTHEAST WEST VIRGINIA THROUGH
EARLY AFTERNOON...BEFORE DIMINISHING WIND SPEEDS DURING THE DAY AS
THE LOW SHIFTS NORTHEAST CAUSE THE SHOWERS TO DISSIPATE. WILL SEE
RISING 500MB HEIGHTS AS THE LOW MOVES AWAY...WHICH WILL TRANSLATE TO
WARMER AFTERNOON TEMPERATURES OVER THOSE OBSERVED ON WEDNESDAY...
WITH HIGHS IN THE LOW/MID 50S ACROSS THE MOUNTAINS...AND IN THE
UPPER 50S TO MID 60S EAST OF THE BLUE RIDGE. BELIEVE THE LOW WILL BE
FAR ENOUGH AWAY BY DAWN FRIDAY THAT WIND SPEEDS WILL DECREASE TO THE
POINT WHERE A FEW OF THE MOUNTAIN VALLEYS DECOUPLE...ALLOWING
RADIATIONAL COOLING TO DROP TEMPERATURES IN THE UPPER 20S TO LOW 30S
IN FEW SPOTS. OTHERWISE...WILL BE LOOKING FOR UPPER 30S TO LOW 40S
MOST LOCATIONS FOR THURSDAY NIGHT LOWS.

FOR FRIDAY...HIGH PRESSURE WILL BE IN CONTROL OF OUR WEATHER PATTERN
IN THE LOW LEVELS. WILL BE KEEPING AN EYE ON A WEAK UPPER LEVEL
TROUGH APPROACHING FROM THE MISSISSIPPI RIVER REGION DURING THE
EVENING HOWEVER. SOME WEATHER FORECAST MODELS ARE IN AGREEMENT THAT
THE ASSOCIATED SHOWER ACTIVITY WILL DIMINISH AS IT RUNS INTO THE
RIDGE OF HIGH PRESSURE STRETCHING NORTHEAST FROM THE GULF COAST
REGION. HOWEVER...A FEW MODELS INDICATE THAT SOME OF THE SHOWERS
SURVIVE TO REACH OUR WESTERN RIDGES...BRINGING LIGHT AND SPOTTY
RAINFALL AMOUNTS. FOR NOW...WILL KEEP A CHANCE FOR SHOWERS IN THE
FORECAST FOR FRIDAY NIGHT...PRIMARILY FOR SOUTHEAST WEST VIRGINIA
AND THE MOUNTAIN EMPIRE...AND SEE HOW THIS SYSTEM EVOLVES OVER THE
NEXT RUN OR TWO OF THE MODELS.

ANOTHER WEAK CLIPPER COLD FRONT WILL PASS ACROSS THE REGION SATURDAY
NIGHT...WITH LITTLE IMPACT TO OUR AREA ASIDE FROM A NORTHWESTERLY
WIND SHIFT. PACIFIC HIGH PRESSURE WILL BUILD IN FROM THE WEST BEHIND
THE COLD FRONT HEADING INTO SUNDAY. WARMER TEMPERATURES ARE EXPECTED
FOR THE END OF THE WEEK AS UPPER LEVEL RIDGING OVER THE CENTER OF
THE NATION BUILDS EAST.

&&

.LONG TERM /SUNDAY THROUGH TUESDAY/...
AS OF 330 AM EDT WEDNESDAY...

THE UPPER RIDGE AXIS WILL CONTINUE TO SHIFT EAST ON SUNDAY...
BECOMING ALIGNED OVER THE EAST COAST ON MONDAY. AS THE RIDGE
APPROACHES...500MB HEIGHTS WILL INCREASE EACH DAY...TRANSLATING INTO
WARMER THAN NORMAL TEMPERATURES FOR THE AREA THROUGH MONDAY. HEIGHTS
WILL BEGIN TO LOWER ON TUESDAY AS THE RIDGE PASSES OFF THE EAST
COAST AND A COLD FRONT ENTERS THE MISSISSIPPI VALLEY.

SURFACE HIGH PRESSURE WILL ACCOMPANY UPPER RIDGING THIS WEEKEND...
PASSING ACROSS OUR AREA SUNDAY NIGHT AND MONDAY. THE SURFACE HIGH
WILL ESSENTIALLY BLOCK ANY RETURN FLOW FROM THE GULF. WITH NO LIFT
AND/OR MOISTURE...HIGH CONFIDENCE TO RUN WITH ZERO POPS INTO MONDAY
NIGHT.

&&

.AVIATION /14Z WEDNESDAY THROUGH SUNDAY/...
AS OF 740 AM EDT WEDNESDAY...

CLOSED LOW WILL DRIFT OFF THE DELMARVA COAST TODAY...AND WILL BE
THE PRIMARY FOCUS FOR WEATHER THROUGHOUT THE REGION THE NEXT
SEVERAL DAYS. THIS FEATURE WILL RESULT IN THE DEVELOPMENT OF A
NOR-EASTER THAT WILL PELT THE NEW ENGLAND COAST WITH HEAVY RAIN A
WIND...AND WILL MOST LIKELY IMPACT AIR TRAFFIC FOR MANY OF THE NEW
ENGLAND TERMINALS FOR THE REMAINDER OF THIS WORK WEEK.

FOR OUR LOCAL REGION...BKN-OVC CLOUD BASES WILL BE COMMON THROUGH
TODAY ACROSS THE MOUNTAINS WITH IFR CIGS FOR BLF AND MVFR FURTHER
EAST. CEILINGS IMPROVE TO VFR/HIGH MVFR TOWARD BCB...AND THEN
SCATTER TO VFR OFF THE BLUE RIDGE. SCATTERED SHOWERS ARE POSSIBLE
OVER THE VA/NC HIGHLANDS...AND ACROSS VIRGINIA NORTH OF A
KROA/KLYH LINE...HIGHWAY 460. ISOLATED SHOWER OR SPRINKLE POSSIBLE
FROM THE VA/NC STATE LINE AND POINTS SOUTH.

WITH THE DEVELOPING CYCLONE TO OUR NORTHEAST...BACKLASH WILL BE
FELT THROUGHOUT OUR REGION IN THE FORM OF GUSTY NORTHWEST WINDS.
3000-5000FT AGL WINDS OF 40 KTS ARE PROGGED FOR WEDNESDAY. THIS
WILL RESULT IN GUSTY SURFACE WINDS AT ALL TERMINALS. 20-30KT
SURFACE GUSTS WILL BE COMMON. THE UPPER LOW WILL SLIDE EASTWARD
TONIGHT INTO THURSDAY. ISOLATED TO SCATTERED SHOWERS WILL CONTINUE
IN THE WEST TONIGHT...WHILE THE EAST WILL DRY OUT.

MEDIUM CONFIDENCE IN CEILINGS...VISIBILITIES AND WINDS DURING THE
PERIOD.


EXTENDED AVIATION DISCUSSION...

THE UPPER LEVEL LOW WILL SLOWLY MEANDER ABOUT THE MID-ATLANTIC
REGION THROUGH THURSDAY...THEN BEGIN TO SHIFT TOWARD THE
NORTHEAST AND AWAY FROM THE AREA BY FRIDAY. IMPACTS...ESPECIALLY FROM
WIND...WILL CONTINUE IN ADDITION TO WIDELY SCATTERED -SHRA ACROSS
THE VA/WV HIGHLANDS EARLY THURSDAY. MVFR CLOUDS WILL THUS BE
COMMON ACROSS THE MOUNTAINS DURING THIS TIME PERIOD...BUT FROM ROA
TO LYH TO DAN CONDITIONS ARE LIKELY TO REMAIN VFR THROUGH THIS
PERIOD.

VFR CONDITIONS ARE ANTICIPATED FRIDAY-SUNDAY. WINDS MAY CONTINUE
TO BE A CONCERN FRIDAY AND SATURDAY...BUT ARE EXPECTED TO DIMINISH
FOR SUNDAY INTO MONDAY AS HIGH PRESSURE BUILDS OVER THE REGION
FROM THE WEST.

&&

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

&&

$$
SYNOPSIS...KK/PM
NEAR TERM...MBS/KK
SHORT TERM...NF
LONG TERM...NF
AVIATION...KK/NF




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