-- Discussion containing changed information from previous version are highlighted. --
000
FXUS61 KLWX 112003
AFDLWX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
303 PM EST WED DEC 11 2013

.SYNOPSIS...
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A REINFORCING COLD FRONT WILL MOVE THROUGH THE AREA TONIGHT.
ARCTIC HIGH PRESSURE WILL BUILD IN BEHIND THE FRONT THURSDAY AND
FRIDAY. LOW PRESSURE WILL MOVE ACROSS THE AREA SATURDAY INTO
SUNDAY. HIGH PRESSURE THEN BRIEFLY BUILDS FOR EARLY NEXT WEEK.
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&&

.NEAR TERM /THROUGH THURSDAY/...
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HIGH PRESSURE HAS RESULTED IN SUNSHINE THIS AFTERNOON ALONG WIT
CHILLY CONDITIONS. A WEAK COLD FRONT IS APPROACH THE AREA FROM THE
OHIO VALLEY.

THE WEAK COLD FRONT WILL PASS THROUGH THE REGION TONIGHT AND A
PRESSURE SURGE BEHIND THE FRONT WILL CAUSE WINDS TO INCREASE
LATE. NORTHWEST WINDS WILL GUST AROUND 15 TO 20 MPH BEHIND
THE COLD FRONT AND AHEAD OF BUILDING ARCTIC HIGH PRESSURE. MIN
TEMPS WILL BE QUITE COLD TONIGHT...RANGING FROM THE SINGLE DIGITS IN
THE MOUNTAINS TO THE TEENS AND LOWER 20S ACROSS MOST OTHER
LOCATIONS. THE COMBINATION BLUSTERY CONDITIONS AND COLD TEMPS WILL
CAUSE LOW WIND CHILLS OVERNIGHT. WIND CHILL VALUES WILL DIP BELOW
ZERO IN THE MOUNTAINS AND INTO THE SINGLE DIGITS AND LOWER TEENS
ACROSS MOST OTHER LOCATIONS. A WIND CHILL ADVISORY IS IN EFFECT FOR
PORTIONS OF THE ALLEGHENY AND POTOMAC HIGHLANDS.

ARCTIC HIGH PRESSURE WILL CONTINUE TO BUILD TOWARD THE REGION
THURSDAY. BLUSTERY CONDITIONS WILL CONTINUE AND NORTHWEST WINDS WILL
USHER IN COLD CONDITIONS...DESPITE SUNSHINE. MAX TEMPS WILL RANGE
FROM THE TEENS IN THE MOUNTAINS TO THE UPPER 20S AND LOWER 30S NEAR
WASHINGTON AND BALTIMORE.
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&&

.SHORT TERM /THURSDAY NIGHT THROUGH FRIDAY/...
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ARCTIC HIGH PRESSURE WILL BUILD OVERHEAD THURSDAY NIGHT...BRINGING
MORE COLD CONDITIONS. HIGH PRESSURE WILL MOVE OFF TO OUR SOUTH FRIDAY
AND LOW PRESSURE WILL MOVE THROUGH THE SOUTHERN CONUS. DRY
CONDITIONS WILL CONTINUE FRIDAY AND IT WILL BE COLD...BUT NOT QUITE
AS COLD AS THURSDAY.  A WIND CHILL ADVISORY MAY BE NEEDED FOR
PORTIONS OF THE ALLEGHENY HIGHLANDS THURSDAY NIGHT INTO FRIDAY.
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&&

.LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/...
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HIGH PRESSURE MOVES OFF THE MID-ATLANTIC COAST LATE FRIDAY...WITH
RETURN FLOW THEN AHEAD OF THE NEXT SYSTEM EJECTING FROM THE SOUTHERN
ROCKIES. ISENTROPIC LIFT CLOUDS THE AREA UP FRIDAY NIGHT...WITH
CHANCE POPS FOR SNOW IN THE WRN HALF OF THE CWA FOR THE LATE
NIGHT. THE 12Z ECMWF IS NOW FASTER WITH PRECIP LATE FRIDAY
NIGHT...ONSET DEPENDS ON MOIST FLOW OVER COMING THE DRY
PRECONDITIONS.

CATEGORICAL POPS LATE SATURDAY INTO SATURDAY
NIGHT. THE INITIAL SFC LOW WILL TRACK ALONG THE WEST SIDE OF THE
APPALACHIANS...SO SLY LOW LEVEL FLOW SHOULD MAKE THIS A WINTRY MIX
CASE. A COASTAL LOW LOOKS TO DEVELOP AS THE UPR TROUGH AXIS
APPROACHES LATE SATURDAY NIGHT. THUS A BRIEF COLD AIR DAMMING
WEDGE MAY DEVELOP SATURDAY NIGHT...LENGTHENING THE TIME FOR WINTRY
P-TYPES AS OPPOSED TO A CHANGEOVER TO RAIN. A SFC HIGH WILL BUILD
OVER NEW ENGLAND SATURDAY...BUT AS OF NOW DOES NOT APPEAR TO WEDGE
IN LIKE THE CASE FROM THIS PAST SUNDAY.

PRECIP WILL END FROM WEST TO EAST ACROSS THE CWA SUNDAY MORNING
AS THE LOW MOVES OFF TO THE NE. COLD BREEZY NWRLY FLOW WILL FILL
IN FOR SUNDAY AND THE BEGINNING OF THE WORKWEEK. UPSLOPE SNOW IS
POSSIBLE FOR AREAS ALONG THE ALLEGANY FRONT ON SUNDAY...WHEN WIND
DIRECTION AND UPSTREAM FETCH WILL BE MOST FAVORABLE. THE REST OF
THE CWA WILL BE DRY THROUGH THE END OF THE PERIOD AS HIGH PRESSURE
PASSES OVERHEAD MONDAY MORNING AND REMAINS IN CONTROL THROUGH THE
MIDDLE OF THE WORKWEEK.
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&&

.AVIATION /20Z WEDNESDAY THROUGH MONDAY/...
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VFR CONDITIONS EXPECTED THROUGH FRIDAY. NORTHWEST WINDS WILL GUST
AROUND 20 KNOTS LATE TONIGHT AND THURSDAY.

LOW PRESSURE BRINGS PRECIP...A WINTRY MIX GENERALLY CHANGING OVER TO
RAIN SATURDAY INTO SATURDAY NIGHT. IFR CONDS POSSIBLE DURING ANY
PRECIP. GENERALLY SLY FLOW AHEAD OF THE COLD FRONT. COLD FRONT
LATE SATURDAY NIGHT BRINGS VFR CONDS AND GUSTY WEST WINDS.

VFR CONDITIONS ARE EXPECTED DURING THE EARLY PORTION OF NEXT WEEK.
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&&

.MARINE...
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A COLD FRONT WILL PASS THROUGH THE WATERS TONIGHT. A PRESSURE SURGE
WILL CAUSE GUSTY NORTHWEST WINDS LATE TONIGHT THROUGH THURSDAY. A
SMALL CRAFT ADVISORY IS IN EFFECT FOR THE WATERS DURING THIS TIME.
HIGH PRESSURE WILL BUILD OVERHEAD THURSDAY NIGHT BEFORE BUILDING TO
OUR SOUTH FRIDAY. WINDS GUSTS WILL BE CLOSE TO SCA CRITERIA OVER THE
WATERS...BUT CAPPED GUSTS AROUND 15 KNOTS FOR NOW DUE TO A WEAKER
PRESSURE GRADIENT.

SLY FLOW IN ADVANCE OF A COLD FRONT SATURDAY INTO SATURDAY NIGHT.
WLY FLOW POST-FRONTAL MAY WARRANT A SMALL CRAFT ADVISORY SUNDAY
ACROSS THE WATERS.

A SMALL CRAFT ADVISORY IS LIKELY AS BREEZY NWRLY FLOW FILLS IN
BEHIND A DEPARTING LOW SUNDAY AND MONDAY.
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&&

.LWX WATCHES/WARNINGS/ADVISORIES...
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DC...NONE.
MD...WIND CHILL ADVISORY FROM MIDNIGHT TONIGHT TO 1 PM EST THURSDAY
     FOR MDZ501.
VA...WIND CHILL ADVISORY FROM MIDNIGHT TONIGHT TO 1 PM EST THURSDAY
     FOR VAZ503-504.
WV...WIND CHILL ADVISORY FROM MIDNIGHT TONIGHT TO 1 PM EST THURSDAY
     FOR WVZ501-503-505-506.
MARINE...SMALL CRAFT ADVISORY FROM MIDNIGHT TONIGHT TO 6 PM EST
     THURSDAY FOR ANZ530>543.
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&&

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