Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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000
FXUS61 KPHI 182338
AFDPHI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
738 PM EDT THU SEP 18 2014

.SYNOPSIS...
A WEAK FRONTAL BOUNDARY WILL MOVE OFFSHORE TONIGHT. HIGH PRESSURE
RETURNS TO THE NORTHEAST TONIGHT AND FRIDAY, THEN WILL SHIFT
OFFSHORE FRIDAY NIGHT. A WARM FRONT WILL LIFT TO OUR NORTHWEST
SATURDAY, THEN A COLD FRONT IS EXPECTED TO AFFECT THE AREA LATE
SUNDAY INTO EARLY MONDAY. THIS FRONT WILL SLOWLY MOVE TO OUR SOUTH
MONDAY, WHILE HIGH PRESSURE BEGINS TO BUILD IN FROM THE WEST. A
WEAKENING FRONT MAY BRIEFLY AFFECT THE AREA ON TUESDAY, BEFORE THE
HIGH FULLY BUILDS ACROSS THE AREA.

&&

.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
NO BIG CHANGES MADE WITH THIS UPDATE. SOME ISOLATED SHOWERS STILL
GOING IN LOWER DELMARVA AS A DEW POINT POOLING PRECEDING THE FRONT
IS SUPPLYING SUFFICIENT MOISTURE TO BE LIFTED. HAVE EXTENDED THE
SLIGHT CHANCE INTO THE EARLY EVENING. TEMPERATURES ARE FALLING
SLIGHTLY FASTER AND WE SMOOTHED THE CURRENT WITH EXPECTED TRENDS
OVERNIGHT. WITH A GRADIENT INCREASING TOWARD MORNING, SOME OF THE
MINS IN LESS SHELTERED PLACES MAY COME SLIGHTLY EARLIER THAN USUAL.

AN UPPER LOW WAS LOCATED OVER EASTERN CANADA LATE THIS AFTERNOON
WHILE ATTENDANT LARGE-SCALE UPPER TROUGH EXTENDED SOUTHWARD DOWN
THE EASTERN SEABOARD. DIFFUSE SFC COLD FRONT ASSOCIATED WITH THIS
SYSTEM WAS POSITIONED NEAR THE NEW ENGLAND COAST, EXTENDING TO THE
SOUTHEAST NEAR I-95 IN THE MID-ATLANTIC STATES.

WEAK CONVERGENCE AND LOCALLY HIGHER MOISTURE NEAR THE SFC FRONT AND
DPVA AHEAD OF A SHORTWAVE TROUGH ALOFT HAS ENHANCED COVERAGE OF
STRATOCU IN SOUTHERN NJ AND DELMARVA AND HAS ALSO LED TO THE
DEVELOPMENT OF A FEW SHOWERS IN NORTHEAST MD DURING THE EARLY
AFTERNOON.

THE COLD FRONT WILL MOVE SOUTH OF THE AREA TONIGHT AS SPRAWLING
CANADIAN HIGH PRESSURE BUILDS SOUTHEAST INTO OUR REGION. CLOUDS WILL
DISSIPATE ACROSS MOST OF THE AREA AFTER SUNSET AS DAYTIME MIXING
WANES AND DRIER AIR ADVECTS INTO THE REGION. CLOUDS MAY LINGER
OVERNIGHT ACROSS THE CENTRAL DELMARVA. MIN TEMPS RANGE FROM NEAR 40F
AT MT POCONO (WHERE SKIES WILL CLEAR TONIGHT) TO NEAR 60F IN GEORGETOWN,
DE (WHERE SKIES WILL REMAIN MOSTLY CLOUDY TONIGHT)

&&

.SHORT TERM /6 AM FRIDAY MORNING THROUGH 6 PM FRIDAY/...
THE CENTER OF HIGH PRESSURE WILL SHIFT SOUTHEASTWARD FROM SOUTHERN
QUEBEC TO THE GULF OF MAINE ON FRIDAY. NORTH-NORTHEAST FLOW AROUND
THE HIGH IN THE MORNING WILL VEER OUT OF THE EAST BY THE END OF THE
DAY FRIDAY AS THE HIGH MOVES OFFSHORE. EXPECT MARINE LAYER TO ADVECT
INLAND DURING THE LATE MORNING AND AFTERNOON. MARINE CLOUDS SHOULD
BE MORE WIDESPREAD ACROSS THE DELMARVA AND SOUTHERN NJ WHERE BOTH
ONSHORE WINDS AROUND THE HIGH AND ISENTROPIC LIFT ARE GREATEST. KEPT
SHOWERS OUT OF THE FORECAST BUT THE 12Z NAM DOES DEPICT LIGHT PRECIP
FOR OUR SOUTHERN ZONES. DO THINK THE NAM WAS TOO BULLISH REGARDING
RETURN OF LOW-LEVEL MOISTURE.

BELOW NORMAL TEMPS ARE EXPECTED AGAIN ON FRIDAY. FORECAST HIGHS
RANGE FROM THE MID 60S IN THE POCONOS TO MID 70S IN THE CENTRAL
DELMARVA.

&&

.LONG TERM /FRIDAY NIGHT THROUGH THURSDAY/...
HIGH PRESSURE BUILDS OFFSHORE OF NEW ENGLAND FRIDAY NIGHT, WHICH
WILL INCREASE AN EASTERLY/SOUTHEASTERLY FLOW ACROSS THE AREA. THIS
COULD LEAD TO A PERIOD OF LOW CLOUDS AND IF THE MOISTURE IS DEEP
ENOUGH, THERE IS POTENTIAL FOR FOG/DRIZZLE TO DEVELOP ACROSS AT
LEAST THE NORTHWESTERN THIRD OF THE AREA. THEREFORE WE HAVE
INTRODUCED PATCHY DRIZZLE AND FOG ACROSS THESE AREAS FRIDAY NIGHT
INTO SATURDAY MORNING.

WITH HIGH PRESSURE OFFSHORE SATURDAY/SATURDAY NIGHT, RETURN FLOW
DEVELOPS WHICH WILL ALLOW DEWPOINTS TO CONTINUE TO INCREASE ACROSS
THE AREA. A WARM FRONT WILL LIKELY LIFT TO OUR NORTHWEST, BUT MAY
NOT PASS CLOSE ENOUGH TO OUR AREA TO BRING ANY EFFECTS. ALSO, THERE
IS A WEAK SHORT WAVE/VORTICITY IMPULSE SATURDAY, BUT WITH LIMITED
VERTICAL MOISTURE, WE DO NOT EXPECT MUCH IN THE WAY OF
PRECIPITATION, SO FOR NOW WE KEEP IT DRY.

ON SUNDAY, A FRONTAL BOUNDARY WILL BE APPROACHING FROM THE WEST. WE
DO NOT EXPECT THE FRONT TO MOVE INTO OUR AREA UNTIL LATER IN THE DAY
ON SUNDAY, BEFORE MOVING ACROSS THE AREA SUNDAY NIGHT INTO EARLY
MONDAY. SO WE WILL HAVE HIGHEST RAIN CHANCES SUNDAY AFTERNOON
INTO SUNDAY NIGHT. THERE IS SOME INSTABILITY ACROSS THE AREA AND
TO THE WEST DURING THE DAY, BUT THE QUESTION IS WHETHER OR NOT WE
LOSE THE INSTABILITY BEFORE THE ACTIVITY REACHES OUR AREA. FOR NOW
WE WILL KEEP THUNDER OUT OF THE FORECAST UNTIL IT LOOKS LIKE WE
HAVE A BETTER SHOT OF INSTABILITY AND PRECIPITATION COINCIDING
WITH EACH OTHER.

ON MONDAY, THE FRONT WILL BE MOVING OUT TO SEA, AND WHAT EVER
SHOWERS ARE LEFT OVER ACROSS THE EASTERN PARTS OF THE AREA WILL MOVE
AWAY WITH IT. HIGH PRESSURE WILL BEGIN BUILDING IN FROM THE WEST
ACROSS THE AREA MONDAY INTO MONDAY NIGHT, BEFORE A WEAKENING
FRONTAL BOUNDARY MOVES INTO THE AREA ON TUESDAY. FOR NOW THE FRONT
LOOKS LIKE IT MAY BE A MOSTLY DRY FRONTAL PASSAGE.

THEN HIGH PRESSURE FULLY BUILDS BACK ACROSS THE AREA FOR THE MIDDLE
OF THE WEEK, WHICH WILL PROVIDE DRY WEATHER ACROSS THE AREA.

&&

.AVIATION /00Z FRIDAY THROUGH TUESDAY/...
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG,
KMIV, KACY AND SURROUNDING AREAS.

VFR TAFS WERE ISSUED AT 00Z. FOR THIS EVENING, SOME RESIDUAL
BORDERLINE LOW/MID LEVEL VFR CLOUDS WITH LIGHT WINDS.

OVERNIGHT THE COLD FRONT SHOULD CLEAR THE TAF SITES AROUND
MIDNIGHT. THERE WILL BE A SLIGHT UPTICK IN WINDS FROM THE NORTH.
THERE MAY STILL BE A FEW RESIDUAL VFR CLOUDS AROUND. DO NOT
BELIEVE MVFR CIG IN WESTERN NY STATE WILL MAKE IT TO THE TAF SITES
(MAYBE THE POCONO AIRPORTS). NO FOG RESTRICTIONS.

ON FRIDAY, WINDS WILL BE SLOWLY VEERING FROM THE NORTHEAST TO
SOUTHEAST AND SPEEDS INCREASING TO AROUND 10 KNOTS AS THE DAY
PROGRESSES. INLAND TERMINALS WITHOUT AN AFTERNOON FORECAST CHANGE
GROUP THE WIND DIRECTION AND SPEED IS THE AVERAGE FOR THE DAY.

WE ARE EXPECTING JUST SCATTERED VFR CUMULUS BASED CLOUDS. AT KACY
AND KMIV, A VFR CIG IS PREDICTED LATE. THIS IS CARRIED INTO KPHL
ON THE 30HR TAF DURING FRIDAY EVENING.


OUTLOOK...
FRIDAY NIGHT...LOWER CIGS AND/OR VSBYS POSSIBLE TO MVFR LEVELS
OVERNIGHT WITHIN A PERSISTENT EASTERLY FLOW.

SATURDAY-SATURDAY NIGHT...MOSTLY VFR DURING THE DAY. LOWER CIGS
AND/OR VSBYS POSSIBLE WITH STRATUS/FOG DEVELOPMENT OVERNIGHT
SATURDAY/SUNDAY MORNING.

SUNDAY-SUNDAY NIGHT...LOWER CONDITIONS POSSIBLE EARLY, THEN VFR
DURING THE DAY. A COLD FRONT APPROACHES LATE IN THE DAY INTO SUNDAY
NIGHT WITH RAIN AND LOWER CONDITIONS POSSIBLE.

MONDAY-TUESDAY...MOSTLY VFR. GUSTY W-NW WINDS 15-20 KNOTS MONDAY AND
TUESDAY AFTERNOON.

&&

.MARINE...
LONG PERIOD SWELLS GENERATED BY EDOUARD CONTINUE TO REACH THE NJ AND
DE COAST THIS AFTN (LATEST OBS SHOW 11-13 SEC WAVE PERIODS). SEAS
AND WINDS EXPECTED TO REMAIN BELOW SCA LEVELS THROUGH FRIDAY
MORNING.

NE WINDS VEER OUT OF THE EAST ON FRIDAY. WINDS WILL INCREASE 15-20
KT WITH ISOLATED GUSTS NEAR 25 KT DURING THE AFTERNOON OVER THE
ATLANTIC COASTAL ZONES. EXPECT SEAS TO BUILD TO 5 FT DURING THIS
TIME OWING TO A LONG ONSHORE FETCH AROUND HIGH PRESSURE OVER THE
GULF OF MAINE. SCA WAS ISSUED FOR THESE ZONES.

OUTLOOK...
FRIDAY NIGHT...SMALL CRAFT ADVISORY IN EFFECT AS WINDS AND SEAS
EXPECTED TO REMAIN ELEVATED IN THE EASTERLY FLOW.

SATURDAY...SEAS MAY REMAIN ELEVATED INTO SATURDAY, SO THE ADVISORY
MAY NEED TO BE EXTENDED INTO SATURDAY.

SATURDAY NIGHT-SUNDAY...CONDITIONS EXPECTED TO DROP BELOW ADVISORY
LEVELS, BUT WINDS MAY GUST NEAR 20 KNOTS.

SUNDAY NIGHT...A COLD FRONT APPROACHES SUNDAY NIGHT WITH RAIN AND
INCREASING WINDS. WINDS MAY APPROACH SMALL CRAFT ADVISORY LEVELS
BEHIND THE COLD FRONT.

MONDAY-TUESDAY...CONDITIONS EXPECTED TO TO DROP BELOW ADVISORY
LEVELS.

&&

.RIP CURRENTS...
IN HOUSE GUIDANCE SUGGESTS A MODERATE RISK TODAY FOR NJ/DE BECAUSE OF
LONG PERIOD SWELLS GENERATED BY EDOUARD.

&&

.PHI WATCHES/WARNINGS/ADVISORIES...
PA...NONE.
NJ...NONE.
DE...NONE.
MD...NONE.
MARINE...SMALL CRAFT ADVISORY FROM 2 PM FRIDAY TO 6 AM EDT SATURDAY FOR
     ANZ451>455.

&&

$$
SYNOPSIS...ROBERTSON
NEAR TERM...GIGI/KLEIN
SHORT TERM...KLEIN
LONG TERM...ROBERTSON
AVIATION...KLINE/ROBERTSON
MARINE...KLEIN/ROBERTSON
RIP CURRENTS...





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