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000
FXUS61 KLWX 181037 AAA
AFDLWX

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
537 AM EST WED DEC 18 2013

.SYNOPSIS...
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HIGH PRESSURE BUILDS INTO THE REGION INTO THIS EVENING BEFORE
MOVING OFFSHORE THURSDAY. A FRONTAL BOUNDARY WILL STALL TO OUR
NORTH AND WEST FRIDAY NIGHT THROUGH SUNDAY BEFORE MOVING THROUGH
SUNDAY NIGHT AND MONDAY MORNING.
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&&

.NEAR TERM /THROUGH THURSDAY/...
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DENSE FOG ADVISORY CANCELLED AS THE FOG OVER N-CNTRL VA MIXED OUT.

AS OF 10Z...POST-FRONTAL CONDITIONS WITH WLY/NWLY FLOW
OCCASIONALLY GUSTING TO 20 MPH. SOME LIGHT RETURNS ARE EVIDENT
OVER THE NRN SHEN VLY AND WEST-CENTRAL MD. WILL NEED TO LOOK FOR
FLURRIES OVER THERE.

AREAS THAT RECEIVED PRECIP LATE IN THE EVENING ARE NOW NEAR OR
BELOW FREEZING. A SPECIAL WEATHER STATEMENT FOR ICY CONDITIONS IS
IN EFFECT UNTIL 730AM FOR DC AND SOUTH.

TODAY...NWLY FLOW...GUSTING 20 TO 25 MPH...WILL QUICKLY MIX DOWN
AFTER SUNRISE ACROSS THE AREA...CLEARING REMAINING FOG. LIGHT
UPSLOPE SNOW CONTINUES WEST FROM THE ALLEGHENY FRONT THROUGH THE
MORNING BEFORE TAPERING OFF BY MIDDAY AS LOW LEVEL FLOW BECOMES SWLY.

COLD AIR ADVECTION AS HIGH PRESSURE BUILDS IN KEEPS TEMPERATURES
BELOW NORMAL...UPR 30S TO AROUND 40F...WITH MID 30S NORTH.

TONIGHT...HIGH PRESSURE MOVES OFFSHORE THIS
EVENING...ALLOWING RETURN SLY/SWLY FLOW. HOWEVER...DRY AIR WILL BE
IN PLACE TONIGHT. HIGH CLOUDS WILL BE PRESENT...BUT ENOUGH
RADIATIONAL COOLING SHOULD ALLOW FOR MID 20S ACROSS INTERIOR
SECTIONS OF THE FORECAST AREA. A LATE CHECK OF THE THE 00Z ECMWF MOS
FOR IAD ACTUALLY HAD 20F. WE HAVE GONE TOO LOW MANY TIMES
RECENTLY...SO THE COLD POTENTIAL TONIGHT WILL NEED TO BE MONITORED.

THURSDAY...DRY WITH WARM AIR ADVECTION. 50S OVER AT LEAST THE SWRN
2/3 OF THE CWA...MID 40S EXPECTED FOR NOW IN N-CNTRL MD.
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&&

.SHORT TERM /THURSDAY NIGHT THROUGH FRIDAY NIGHT/...
HIPRES THAT IS CENTERED OVER THE WRN ATLANTIC WILL RIDGE WWD INTO
THE SOUTHEAST STATES LATE IN THE WEEK. FARTHER UPSTREAM...A FRONTAL
BOUNDARY STRETCHING FROM UPSTATE NY SEWD INTO TX WILL STALL ON FRI
AS IT APPROACHES THE BLOCKING RIDGE TO THE S AND E. MOST OF THE AREA
SHOULD BE DRY DURING THE PERIOD WITH THE BULK OF THE PRECIP NEAR THE
FRONT REMAINING N AND W OF THE CWA. SOME LGT SHOWER ACTIVITY MAY
BRUSH THE FAR N/W BORDER OF THE CWA LATE FRI AFTN AND FRI NGT IF THE
BOUNDARY WINDS UP STALLING SLIGHTLY FARTHER EAST THAN MODEL GUIDANCE
INDICATES.

STRENGTHENING SWLY FLOW AHEAD OF THE COLD FRONT WILL DRAW A WARM/
MOIST AIRMASS NWD UP THE ERN SEABOARD. ABOVE NORMAL TEMPS EXPECTED
ON FRI WITH HIGHS IN THE LOWER 60S EXPECTED AS FAR NORTH AS CENTRAL
VA AND SRN MD.

&&

.LONG TERM /SATURDAY THROUGH TUESDAY/...
MODELS ARE IN GOOD AGREEMENT WITH THE POSITION OF THE AFOREMENTIONED
FRONT...WHICH IS EXPECTED TO REMAIN STALLED OVER THE TN/OH VLYS AND
NORTHEAST STATES THRU MOST OF THE WEEKEND.

TREND WAS TO LOWER POPS WITH MOST OF THE PRECIP FOCUSED NEAR THE
FRONT. THERE IS STILL A POSSIBILITY FOR SOME SHOWERS TO REACH THE
POTOMAC HIGHLANDS AND NRN MD ON SAT.

A WAVE OF LOPRES THAT DEVELOPS IN TX ON SAT IS FCST TO TRACK NEWD
ALONG THE BOUNDARY. NW FLOW WILL DEVELOP ON THE BACKSIDE OF THE
LOW...ALLOWING THE FRONT TO FINALLY MOVE THRU THE AREA ONCE THE LOW
MOVES NORTH OF THE AREA LATE SUN AND ERY MON. THERE ARE STILL TIMING
DIFFERENCES REGARDING THE FROPA...BUT IT APPEARS THE BEST COVERAGE
OF SHOWERS WILL BE SUN AFTN AND NGT. A DEEP SLY TRANSPORT FROM THE
GULF OF MEXICO WILL BE YIELD AN ANOMALOUSLY WARM/MOIST AIRMASS AHEAD
OF THE FRONT. GEFS MEAN SHOWS A +3-4 SD PWAT OVER THE MID-ATLANTIC
REGION ON SUNDAY. THERE IS A LIMITED POTENTIAL FOR TSTMS AHEAD OF
THE FRONT. EVEN WITH CLOUD COVER OVER THE AREA...DID NOT GO QUITE AS
WARM FOR HIGHS ON SUN /NEAR 80F IN SOME SPOTS/. MAX T AROUND 70F ARE
NOT OUT OF THE QUESTION...WHICH WOULD BE CLOSE TO RECORD HIGHS.

THE COLD FRONT IS EXPECTED TO PROGRESS S/E OF THE AREA MON. STRONG
CAA WILL OCCUR BEHIND THE FRONT. TEMPS RETURN TOWARD NORMAL BY TUE.

&&

.AVIATION /12Z WEDNESDAY THROUGH SUNDAY/...
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NWLY FLOW MIXES DOWN QUICKLY WITH SUNRISE OR PERHAPS JUST BEFORE.
ALL VFR BY MID MORNING WITH NWLY GUSTS AROUND 20 KT INTO THE MID-
AFTERNOON. HIGH PRESSURE BUILDS ACROSS THIS EVENING...WITH LIGHT
SLY FLOW LATE TONIGHT THROUGH THURSDAY.

VFR LATE IN THE WEEK WITH SLY RETURN FLOW DEVELOP AROUND A WRN
ATLANTIC RIDGE. WINDS COULD GUST NEAR 20 KT ON FRI AND SAT.

POTENTIAL FOR SUB-VFR CIGS/VSBYS AND SHRA INCREASE THRUOUT THE
WEEKEND AS A FRONTAL BOUNDARY STALLS TO THE N/W. THE FRONT WILL MOVE
THRU LATE SUN INTO ERY MON. BREEZY SLY WINDS POSSIBLE AHEAD OF THE
FRONT ESPECIALLY ON SUN WHEN A LLVL JET MOVES OVERHEAD. LLWS ALSO
POSSIBLE.
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&&

.MARINE...
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LULL IN SCA WINDS THIS MORNING...BUT WIDESPREAD GUSTS OF 20 TO
25 KT ARE EXPECTED BY OR SHORTLY AFTER SUNRISE. THEREFORE...
THE SCA WILL REMAIN IN EFFECT FOR ALL WATERS. HIGH PRESSURE
BUILDS ACROSS THIS EVENING. SCA ENDS AT 6PM.

HIPRES MOVES OFFSHORE FRI. A SCA MAY BE NEEDED FOR PORTIONS OF
THE AREA FRI. SCA LIKELY FOR SAT AND SUN WHEN SLY WINDS INCREASE
AHEAD OF A SLOW MOVING FRONT.
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&&

.LWX WATCHES/WARNINGS/ADVISORIES...
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DC...NONE.
MD...NONE.
VA...NONE.
WV...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 6 PM EST THIS EVENING FOR
     ANZ530>543.
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&&

$$
UPDATE...JACKSON
PREVIOUS...JACKSON/KLEIN