Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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000
FXUS61 KPHI 210438
AFDPHI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
1238 AM EDT SUN SEP 21 2014

.SYNOPSIS...
A WAVE OF LOW PRESSURE OFF THE SOUTHEAST COAST WILL MOVE NORTHWARD
UP THE EASTERN SEABOARD THROUGH SUNDAY WHILE A COLD FRONT
APPROACHES FROM THE WEST. THE FRONT IS EXPECTED TO MOVE THROUGH
THE MID- ATLANTIC STATES SUNDAY NIGHT. HIGH PRESSURE BUILDING IN
FROM THE MIDWEST EARLY IN THE WEEK WILL PERSIST OVER THE AREA
THROUGH THE END OF THE WEEK.

&&

.NEAR TERM /UNTIL 6 AM THIS MORNING/...
LOW CLOUDS HAVE STARTED TO PUSH IN ACROSS THE REGION AND SHOULD
CONTINUE TO REMAIN OVER THE AREA THROUGH THE MORNING.

SOME SHOWERS ARE LOCATED JUST OFFSHORE AND ARE MOVING NORTHWARD. A
FEW SHOWERS MAY MOVE OVER THE COASTAL AREAS, BRINGING A BRIEF
PERIOD OF RAIN TO THE AREA. DON`T EXPECT THE SHOWERS TO MAKE IT
TOO FAR INLAND AT THIS POINT AS THE FEATURE THEY ARE ASSOCIATED
WITH IS STILL PRETTY FAR AWAY. IN ADDITION, WHERE RAIN FALLS WE
WILL SEE AN INCREASED CHANCE FOR SOME FOG DEVELOPMENT OVERNIGHT.

WINDS HAVE GONE LIGHT AND VARIABLE AT MOST LOCATIONS AND WHERE
WIND EXISTS, IT WILL BE LIGHT OUR OF THE EAST OR SOUTHEAST.
MOISTURE HAS INCREASED THROUGHOUT THE DAY AND DEWPOINTS ARE
CREEPING UP INTO THE 60S ACROSS THE AREA.

WITH CONSIDERABLE CLOUD COVER ACROSS THE REGION, TEMPERATURES WILL
BE ON THE WARMER SIDE OVERNIGHT. GENERALLY WE WILL SEE TEMPS IN TO
EH UPPER 50S TO MID 60S ACROSS THE REGION, WITH SOME COOLER TEMPS
ACROSS THE FAR NORTH.

&&

.SHORT TERM /6 AM THIS MORNING THROUGH 6 PM TONIGHT/... LOW PRESSURE IS
SHOWN MOVING UP ALONG THE COAST SUNDAY WHILE A SECOND LOW MOVES
ACROSS THE GREAT LAKES AND HEADS TOWARD THE ST. LAWRENCE VALLEY. A
COLD FRONT ATTACHED TO THE SECOND LOW WILL APPROACH FROM THE WEST
DURING THE AFTERNOON. SHOWERS WILL OCCUR WITH THE FIRST LOW...NEAR
THE SHORE AREAS EARLY...THEN WITH THE COLD FRONT OVER THE NRN/WRN
AREAS LATE. IT WILL LIKELY BE A MOSTLY CLOUDY START TO THE DAY AND
SOME MORNING FOG MAY BE SLOW TO BURN OFF. LIMITED SUN WILL BE
ENOUGH TO BRING TEMPERATURES INTO THE UPPER 70S TO LOW 80S IN MOST
AREAS. WINDS WILL BE LIGHT EARLY...THEN FAVOR A SRLY/SWRLY
DIRECTION AHEAD OF THE APPROACHING FRONT.

&&

.LONG TERM /SUNDAY NIGHT THROUGH SATURDAY/...
A COLD FRONT IS FORECAST TO MOVE THROUGH THE AREA SUNDAY NIGHT.
MODELS ARE IN GOOD AGREEMENT WITH TIMING OF FROPA OCCURRING DURING
THE EVENING WEST OF I-95 AND OVERNIGHT FARTHER TO THE EAST. EXPECT
TO SEE A BRIEF PERIOD OF SHOWERS WITH THE FROPA AS FORCING FOR
ASCENT ASSOCIATED WITH THE UPPER TROUGH AND JET STREAK TRAVERSES
THE AREA. THE TROUGH WILL BE DEEPENING AS IT APPROACHES THE
EASTERN SEABOARD, BUT AMPLIFICATION IS FORECAST TO OCCUR TOO LATE
FOR DEEPER MOISTURE FROM THE GULF OF MEXICO OR ATLANTIC TO REACH
OUR AREA IN TIME. THE FORECAST PRE-FRONTAL ENVIRONMENT FROM 12Z
GFS/NAM AND 09Z SREF BUFKIT SOUNDINGS IS CHARACTERIZED BY WEAK
LAPSE RATES AND MEAGER INSTABILITY. DO NOT EXPECT PRECIP TO BE
PARTICULARLY HEAVY OR WIDESPREAD UNDER THIS SETUP.

THE COLD FRONT WILL MOVE OFFSHORE WHILE HIGH PRESSURE BUILDS IN FROM
THE MIDWEST STATES. NORTHWEST WINDS BEHIND THE COLD FRONT WILL USHER
IN NOTICEABLY COOLER AND DRIER AIR ON MONDAY IN A TIMELY FASHION FOR
THE FIRST DAY OF AUTUMN. MAX TEMPS RANGE FROM NEAR 60F IN THE
POCONOS TO MID 70S IN THE DELMARVA/SOUTHERN NJ. CLOUDS WILL LIMIT
SUNSHINE ESPECIALLY ACROSS THE NORTHERN AND WESTERN TIER OF THE CWA.
MODELS OFTEN UNDER DO THE POST-FRONTAL STRATOCU DEVELOPMENT DURING
SIGNIFICANT CAA REGIMES.

A QUIET WX PATTERN WILL CONTINUE INTO AT LEAST THE MIDDLE OF THE
WEEK WITH HIGH PRESSURE BUILDING IN DURING THIS TIME. A CUTOFF LOW
IS FORECAST TO DEVELOP OVER THE SOUTHEAST STATES DURING THE FIRST
HALF OF THE WEEK. THERE WAS SOME HINT AT THIS LOW DRIFTING NORTHWARD
UP THE EASTERN SEABOARD AND THEN POSSIBLY IMPACTING PORTIONS OF THE
FORECAST AREA LATE IN THE WEEK. HOWEVER, PREDICTABILITY IN THIS
SETUP IS LOWER THAN NORMAL DUE TO A LACK OF STEERING FLOW UNDERNEATH
THE RIDGE. ASIDE FROM THE 12Z OPERATIONAL ECMWF, DID NOT HAVE ENOUGH
SUPPORT FROM NWP GUIDANCE TO WARRANT A SIGNIFICANT CHANGE TOWARD A
MORE PESSIMISTIC (I.E., CLOUDY AND RAINY) FORECAST FOR LATE IN THE
WEEK. CONFINED SLIGHT CHANCE POPS TO THE DELMARVA THURSDAY.
OTHERWISE, A DRY FORECAST IS ADVERTISED THRU THE END OF THE
LONG-TERM PERIOD.

NEAR TO SLIGHTLY BELOW NORMAL TEMPS EXPECTED EARLY IN THE WEEK
BEHIND THE COLD FRONT AND CONTINUE THRU THE END OF THE WEEK WITH
PERSISTENT ONSHORE FLOW.

&&

.AVIATION /06Z SUNDAY THROUGH THURSDAY/...
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG,
KMIV, KACY AND SURROUNDING AREAS.

CEILINGS HAVE STARTED TO FALL TO MVFR/IFR CONDITIONS. EXPECT
CEILINGS TO REMAIN DOWN THROUGH THE NIGHT, ALTHOUGH THERE MAY BE
BRIEF PERIODS WHERE SKIES SCATTER OUT. WITH LIGHT WINDS, WITH A
SLIGHT EASTERLY FLOW, EXPECT THE DOWNWARD TREND TO CONTINUE ACROSS
THE TERMINALS.

SOME LIGHT SHOWERS OR PATCHY DRIZZLE MAY OCCUR CLOSE TO THE
SHORE. THIS WAS PLACED IN A TEMPO GROUP FOR KACY. SHOULD RAIN
OCCUR AT ANY TERMINALS, THE CHANCE FOR FOG DEVELOPMENT WOULD
INCREASE OVERNIGHT.

SUNDAY...SLOW RECOVERY BACK TO VFR WITH AN APPROACHING COLD FRONT
AND A GRADUAL SWITCH IN WINDS TO SW. IT IS LIKELY THAT MOST SITES
WILL BE BACK TO VFR 14Z- 16Z.

OUTLOOK...

SUNDAY NIGHT...COLD FRONT MOVES THRU THE TERMINALS. SCT SHRA ALONG
AND AHEAD OF THE FRONT BUT GENERALLY VFR CONDITIONS EXPECTED. WIND
SHIFT FROM SW TO NW WILL OCCUR WITH THE FROPA.

MONDAY...NW WIND GUSTS AROUND 20 KT ARE POSSIBLE MONDAY IN
ASSOCIATION WITH POST-FRONTAL PRESSURE SURGE. STRATOCU FAVORED IN
THIS SETUP, WHICH MAY RESULT IN A PERIOD MVFR CIGS FOR PHILLY
TERMINALS NORTH AND WEST.

MONDAY NIGHT THROUGH THURSDAY...VFR AND LIGHT WINDS EXPECTED.

&&

.MARINE...
THE SCA FLAG OUT PRESENTLY FOR THE COASTAL WATERS WILL BE EXTENDED
IN TIME...SINCE THE APPROACHING LOW WILL NOT DO ANYTHING TO REDUCE
THE POTENTIAL FOR ENHANCED SEAS. WE WILL ADD THE NRN-MOST COASTAL
ZONE TO THE MIX THIS EVENING...WHEN THE HIGHER SEAS WILL (PROBABLY)
ARRIVE THERE. THE SCA FLAG WILL CONTINUE THRU NOON SUNDAY. BY THEN
THE BEST PRESSURE GRADIENT WITH THE OFFSHORE LOW WILL HAVE WEAKENED
ACROSS THE WATERS. SCT SHOWERS ARE EXPECTED TONIGHT AND EARLY
SUNDAY.

OUTLOOK...

SUNDAY NIGHT THROUGH MONDAY...A COLD FRONT WILL MOVE THRU THE WATERS
LATE SUNDAY NIGHT. SW FLOW AHEAD OF THE FRONT WILL SHIFT OUT OF THE
NW. POST-FRONTAL NW WINDS OF 15-20 KT GENERALLY EXPECTED BUT CANNOT
RULE OUT LOCALLY STRONGER GUSTS LATE SUNDAY NIGHT INTO MONDAY.
LATEST GUIDANCE ALSO SHOWS SEAS INCREASE TO 4-6 FT IN THE ATLANTIC
JUST OFF THE DE/NJ COAST DURING THIS TIME. OPTED TO HOLD OF ON
ISSUING A SCA WITH ANOTHER SCA IN EFFECT THRU NOON SUNDAY AND A LULL
IN SCA CONDITIONS EXPECTED FOR 6-12 HOURS.

MONDAY NIGHT THROUGH THURSDAY...SUB-SCA CONDITIONS EXPECTED ATTM.

&&

.PHI WATCHES/WARNINGS/ADVISORIES...
PA...NONE.
NJ...NONE.
DE...NONE.
MD...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL NOON EDT TODAY FOR ANZ450>455.

&&

$$
SYNOPSIS...KLEIN/MEOLA
NEAR TERM...MEOLA
SHORT TERM...O`HARA
LONG TERM...KLEIN
AVIATION...KLEIN/MEOLA
MARINE...KLEIN/O`HARA







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