Area Forecast Discussion
Issued by NWS Sterling, VA

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000
FXUS61 KLWX 270854
AFDLWX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
354 AM EST THU NOV 27 2014

.SYNOPSIS...
AN UPPER-LEVEL DISTURBANCE WILL PASS THROUGH THE AREA TODAY AND
HIGH PRESSURE WILL BUILD OVERHEAD FRIDAY. THE HIGH WILL MOVE OFF
THE COAST DURING THE WEEKEND. A COLD FRONT IS EXPECTED TO MOVE
THROUGH MONDAY.

&&

.NEAR TERM /THROUGH TONIGHT/...
COASTAL LOW PRESSURE THAT BROUGHT RAIN AND SNOW TO THE MID-ATLANTIC
WEDNESDAY WILL CONTINUE TO DEEPEN OFF THE MAINE COAST THIS MORNING.
HIGH PRESSURE HAS RIDGED INTO THE REGION FROM THE SOUTH THIS MORNING
AHEAD OF A WEAK AREA OF LOW PRESSURE.

SUBSIDENCE HAS LED TO AREAS OF CLEARING EARLY THIS MORNING. PATCHY
FOG HAS DEVELOPED AS CALM WINDS LEAD TO RADIATIONAL COOLING ACROSS
THE WET GROUND. DENSE FOG HAS BEEN OBSERVED IN VALLEY LOCATIONS
ESPECIALLY IN THE SHENANDOAH VALLEY. A DENSE FOG ADVISORY IS IN
EFFECT THIS MORNING FOR THE SHENANDOAH VALLEY. CLOUDS FROM THE
APPROACHING DISTURBANCE WILL CONTINUE TO MOVE INTO THE MID-ATLANTIC
FROM THE TN VALLEY. THIS SHOULD HALT FOG DEVELOPMENT FURTHER EAST
BUT DUE TO THE SNOWPACK WEST OF THE BLUE RIDGE...DENSE FOG WILL
CONTINUE ACROSS THE SHEN VALLEY. TEMPS WILL REACH THE UPPER 20S AND
LOW 30S ACROSS THE REGION. ICY CONDITIONS FROM REFREEZE ARE POSSIBLE
THIS MORNING.

A SHORTWAVE TROUGH HAS MOVED INTO THE TN VALLEY THIS MORNING.
WEAKENING LOW PRESSURE AHEAD OF THE TROUGH WILL CROSS SW VA THIS
MORNING AND OFF THE CAROLINA COAST BY THIS AFTERNOON. SHOWERS HAVE
BEEN OBSERVED ACROSS THE TN VALLEY/APPALACHIAN REGION OVERNIGHT.
THEY WILL PIVOT NORTHWARD THIS MORNING AS THE TROUGH AXIS SWINGS
APPROACHES THE REGION. THE TRACK OF THE LOW WILL KEEP MOST OF THE
ACTIVITY SOUTH OF THE LWX REGION. LIGHT SHOWERS MAY SKIRT THE
CENTRAL FOOTHILLS AND PIEDMONT TODAY. MAINLY RAIN SHOWERS ARE
EXPECTED IN THIS AREA WITH THE EXCEPTION OF THE PRE DAWN HRS WHERE
TEMPS DROPPING TO AROUND FREEZING WILL LEAD TO SNOW SHOWERS THIS
MORNING. TEMPS WILL RISE INTO THE UPPER 30S TO 40S TODAY.

AS LOW PRESSURE MOVES SOUTH OF THE REGION AND THE UPPER LEVEL TROUGH
AXIS MOVES ACROSS THE REGION WESTERLY WINDS WILL INCREASE. UPSLOPE
SNOW SHOWERS ARE POSSIBLE LATE THIS MORNING THROUGH TONIGHT. UP TO
THREE INCHES IS POSSIBLE TODAY AND TONIGHT ACROSS THE WESTERN
SLOPES. FURTHER EAST...COLD AIR ADVECTION WILL LEAD TO A STRATO-CU
DECK AND SPRINKLES/FLURRIES ARE EXPECTED AS THE UPPER LEVEL TROUGH
PASSES OVERHEAD TODAY.

HIGH PRESSURE WILL MOVE INTO THE REGION TONIGHT. SNOW SHOWERS ON THE
WESTERN SLOPES WILL TAPER OFF BY FRIDAY MORNING. FCST MIN TEMPS WILL
RANGE FROM THE LOW 20S IN THE MTNS TO THE LOW 30S NEAR THE CITIES.

&&

.SHORT TERM /FRIDAY THROUGH SATURDAY/...
STILL MAY HAVE A FEW UPSLOPE SNOW SHOWERS ONGOING TO START FRIDAY
OTHERWISE SURFACE HIGH BUILDS IN FROM THE WEST FOR DRY
CONDITIONS/SOME SUNSHINE BUT BELOW NORMAL TEMPERATURES.

SURFACE HIGH SHIFTS OFFSHORE FRIDAY NIGHT. SHORTWAVE IN 500 MB FLOW
WILL BRING INCREASING CLOUDS FRIDAY NIGHT INTO EARLY SATURDAY. MUCH
OF THE CWA SHOULD BE DRY ALTHOUGH THERE WILL BE A SLIGHT CHANCE OF
SNOW SHOWERS OVER THE ALLEGHENY/POTOMAC HIGHLANDS. TEMPERATURES
START TO MODERATE A LITTLE FOR SATURDAY.

&&

.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
RETURN FLOW AROUND HIGH PRESSURE LOCATED OFFSHORE WILL MODERATE
TEMPERATURES MORE SATURDAY NIGHT INTO SUNDAY. A WARM FRONT WILL
LIKELY PUSH NORTH FOR SUNDAY. THERE WILL BE SOME CLOUDS BUT CHANCE
OF PRECIP APPEARS MINIMAL.

ABOVE NORMAL TEMPERATURES ARE LIKELY TO PERSIST INTO MONDAY. A COLD
FRONT WILL MOVE ACROSS THE AREA WITH A CHANCE OF RAIN SHOWERS.
COLDER AIR IS THEN EXPECTED TO MOVE IN BEHIND THE FRONT FOR THE
MID-WEEK PERIOD.

&&

.AVIATION /08Z THURSDAY THROUGH MONDAY/...
MVFR/IFR CONDITIONS DUE TO FOG DEVELOPMENT HAS LED TO SUDDEN DROPS
IN VSBYS AT CHO THIS MORNING. THIS IS POSSIBLE AT MRB-IAD THROUGH
THE DAWN HOURS. LIGHT SW WINDS WILL BECOME NW 5-10 KTS THIS
AFTERNOON AT THE TERMINALS. VFR CONDITIONS EXPECTED LATER TODAY AND
TONIGHT.

HIGH PRESSURE BUILDS IN FOR FRIDAY THEN MOVES OFFSHORE FOR THE
WEEKEND. NO SIGNIFICANT WX IS EXPECTED.

&&

.MARINE...
NRLY WINDS HAVE SUBSIDED ON THE WATERS OVERNIGHT AS THE COASTAL LOW
MOVES FURTHER AWAY. WEAK LOW PRESSURE WILL MOVE SOUTH OF THE WATERS
TODAY LEADING TO NW WINDS 10-15KTS TODAY. NRLY WINDS BEHIND THE LOW
WILL INCREASE AND SCA CONDITIONS WILL BE POSSIBLE TONIGHT FOR
PORTIONS OF THE WATERS BECOMING ALL THE WATERS FRIDAY.

NORTHWEST WINDS BEHIND A SHORTWAVE SHOULD BE ABLE TO MIX DOWN FOR
SCA CONDITIONS ON FRIDAY. HIGH PRESSURE BUILDS IN FOR LESS WIND
FRIDAY NIGHT. RETURN FLOW ON SATURDAY COULD THEN INCREASE INTO SCA
TERRITORY.

&&

.LWX WATCHES/WARNINGS/ADVISORIES...
DC...NONE.
MD...NONE.
VA...DENSE FOG ADVISORY UNTIL 9 AM EST THIS MORNING FOR VAZ025>027-
     029-030-504.
WV...DENSE FOG ADVISORY UNTIL 9 AM EST THIS MORNING FOR WVZ055-502-
     506.
MARINE...SMALL CRAFT ADVISORY FROM 7 PM THIS EVENING TO 6 PM EST FRIDAY
     FOR ANZ530>534-536-537-539>541-543.
     SMALL CRAFT ADVISORY FROM 8 AM TO 6 PM EST FRIDAY FOR ANZ535-
     538-542.

&&

$$
SYNOPSIS...HAS/BPP
NEAR TERM...HAS
SHORT TERM...BPP
LONG TERM...BPP
AVIATION...HAS/BPP
MARINE...HAS/BPP







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