Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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000
FXUS61 KPHI 200109
AFDPHI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
909 PM EDT FRI SEP 19 2014

.SYNOPSIS...
HIGH PRESSURE WILL SHIFT OFFSHORE TONIGHT. A WARM FRONT WILL LIFT TO
OUR NORTHWEST SATURDAY, THEN A COLD FRONT IS EXPECTED TO AFFECT THE
AREA LATE SUNDAY INTO SUNDAY NIGHT. THIS FRONT WILL MOVE TO OUR
SOUTH, WHILE HIGH PRESSURE BEGINS TO BUILD IN FROM THE WEST ON
MONDAY. A WEAKENING FRONT MAY BRIEFLY AFFECT THE AREA ON TUESDAY,
BEFORE THE HIGH FULLY BUILDS ACROSS THE AREA FOR MUCH OF THE
REMAINDER OF THE WEEK.

&&

.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
ESTF FOR 930 PM UPDATE: PATCHES OF SC SHOULD BECOME MORE WIDESPREAD
OVERNIGHT IN THE WEAK EASTERLY FLOW AND FORMED/REFORMED JUST BELOW
THE INVERSION NEAR 3000 FT. TIMING WHEN THIS HAPPENS IS UNCERTAIN.
TEMPS WILL HAVE SLIGHT ADJUSTMENTS BUT DO NOT EXPECT ANY MAJOR
CHANGES. PATCHY FOG POSSIBLE LATE...MAINLY NEAR AND NW OF I95.

&&

.SHORT TERM /6 AM SATURDAY MORNING THROUGH 6 PM SATURDAY/...
HIGH PRESSURE WILL MOVE FARTHER OFFSHORE INTO THE NORTHERN ATLANTIC
WATERS ON SATURDAY. AN AREA OF LOW PRESSURE IS FORECAST TO TRACK
NORTH OF THE GREAT LAKES WHILE ANOTHER LOW PRESSURE SYSTEM DEVELOPS
OFF THE SOUTHEAST COAST. THE PATTERN IN BETWEEN THESE TWO SYSTEMS
WILL ALLOW THE ABOVE MENTIONED HIGH OVER THE ATLANTIC TO RIDGE BACK
WESTWARD INTO THE MID-ATLANTIC STATES.

SOUTHERLY FLOW AROUND THE PERIPHERY OF THE HIGH WILL PROMOTE WAA IN
THE LOW LEVELS. THIS PATTERN WILL RESULT IN MAX TEMPS THAT ARE 5-10F
WARMER ON SATURDAY THAN TODAY. SATURDAY MAY POTENTIALLY BE THE FIRST
DAY WITH ABOVE NORMAL TEMPS SINCE SEP 11, ALBEIT NOT MUCH MORE THAN
A COUPLE OF DEGREES ABOVE.

MODEL BUFKIT SOUNDINGS DEPICT A SATURATED BOUNDARY LAYER INITIALLY
SATURDAY MORNING AS A RESULT OF THE ONSHORE FLOW AT THE START OF THE
PERIOD. THE 12Z NAM TRIES TO MIX OUT MOISTURE AND RESULTANT CLOUDS
RATHER QUICKLY (BY 15Z) ACROSS THE ENTIRE CWA WHILE THE 12Z GFS
INDICATES A MUCH CLOUDIER SOLUTION ALONG AND EAST OF THE FALL LINE
THRU MUCH OF THE DAY AS MARINE AIR IS STUBBORN TO MIX OUT. DEEPER
MOISTURE IN THE COLUMN AS FORECAST BY THE 12Z WOULD INDICATE THE
POTENTIAL FOR SHOWERS TO DEVELOP NEAR THE COAST WITH THE ONLY
DISCERNIBLE FORCING MECHANISM BEING LOW-LEVEL ISENTROPIC LIFT. KEPT
POPS VERY LOW DUE TO THE UNCERTAINTY AND CONFINED SLIGHT CHANCE FOR
SHOWERS TO COASTAL LOCALES SINCE MOISTURE FLUX IF FORECAST TO BE
GREATEST OFFSHORE.

&&

.LONG TERM /SATURDAY NIGHT THROUGH FRIDAY/...
SATURDAY NIGHT, HIGH PRESSURE PULLS AWAY TO OUR NORTHEAST AHEAD
OF THE APPROACHING COLD FRONT. AT THE SAME TIME, AN AREA OF LOW
PRESSURE WILL BE MOVING ALONG THE EAST COAST NEAR THE CAROLINA
COASTS. THE LOW WILL MOVE NORTHWARD AND PASS EAST OF OUR AREA, BUT
WILL LIKELY NOT PASS CLOSE ENOUGH TO OUR AREA TO BRING ANY
SIGNIFICANT IMPACTS BEFORE THE FRONT APPROACHES AND PUSHES IT
NORTHEASTWARD. WE MAY HAVE ANOTHER POSSIBILITY FOR LOW CLOUDS AND
FOG AND/OR DRIZZLE AS THE LOW APPROACHES SATURDAY NIGHT AND THE
LOW LEVELS MOISTEN. SO WE HAVE ADDED PATCHY FOG/DRIZZLE FOR
SATURDAY NIGHT/SUNDAY MORNING.

THE FRONTAL BOUNDARY SHOULD BE ENTERING OUR WESTERN AREAS DURING
SUNDAY AFTERNOON, BEFORE SWEEPING ACROSS OUR AREA SUNDAY EVENING
AND SUNDAY NIGHT. MODELS HAVE THE HIGHEST POPS AND QPF MOSTLY TO
OUR WEST DURING THE DAY, BEFORE LOWERING AS THE FRONT MOVES
THROUGH OUR AREA SUNDAY EVENING. SO WE WILL HAVE HIGHEST RAIN
CHANCES SUNDAY AFTERNOON ACROSS THE NORTHWESTERN AREAS,
DIMINISHING TO LOW END CHANCE SUNDAY EVENING. THERE IS SOME
INSTABILITY ACROSS THE AREA AND ESPECIALLY TO THE WEST DURING THE
DAY, BUT THE QUESTION IS WHETHER OR NOT WE LOSE THE INSTABILITY
BEFORE THE ACTIVITY REACHES OUR AREA. WE WILL MAINTAIN THE SLIGHT
CHANCE OF THUNDERSTORMS AS THERE IS THE POSSIBILITY FOR SOME
ISOLATED CONVECTION.

ON MONDAY, THE FRONT WILL BE MOVING OUT TO SEA, WHILE HIGH PRESSURE
BEGINS BUILDING IN FROM THE WEST ACROSS THE AREA THROUGH MONDAY
NIGHT. A WEAKENING FRONTAL BOUNDARY MAY BRIEFLY AFFECT THE AREA ON
TUESDAY, BUT FOR NOW THE FRONT LOOKS LIKE IT SHOULD BE A MOSTLY DRY
FRONTAL PASSAGE.

THEN HIGH PRESSURE FULLY BUILDS BACK ACROSS THE AREA FOR MUCH OF
THE REMAINDER OF THE WEEK, WHICH WILL PROVIDE DRY WEATHER ACROSS
THE AREA. ACTUALLY, THE FRONTAL PASSAGE SUNDAY/SUNDAY NIGHT LOOKS
LIKE OUR ONLY CHANCE OF RAIN FOR THE ENTIRE EXTENDED PERIOD, SO
LETS HOPE WE GET SOMETHING FROM IT.

TEMPERATURES ON SUNDAY WILL BE THE WARMEST OF THE EXTENDED WITH
TEMPERATURES 5-10 ABOVE NORMAL. THEN TEMPERATURES RETURN CLOSER
TO NORMAL OR FOR THE REMAINDER OF THE PERIOD.

&&

.AVIATION /01Z SATURDAY THROUGH WEDNESDAY/...
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG,
KMIV, KACY AND SURROUNDING AREAS.

TONIGHT...SCT CLOUDS AOA 3500 FT WITH PATCHY MVFR CIGS ALONG THE
COASTS. THE MVFR CIGS SHOULD BECOME WIDESPREAD OVERNIGHT. I MAY
HAVE STARTED THE FILLING IN OF THE LOWER CIGS SEVERAL HOURS TOO
SOON? LIGHT EASTERLY FLOW.

SATURDAY...MVFR CIGS MAY BREAK TO BECOME VFR SCT-BKN AOA 3500 FT
IN THE EARLY AFTN. LIGHT SE FLOW. THERE IS UNCERTAINTY CONCERNING
HOW QUICKLY LOW CLOUDS ERODE AND CIGS IMPROVE TO VFR. HAVE A
SHOWER IN THE TAF FOR KMIV AND KACY CLOSER TO THE COASTAL
INSTABILITY BURST. GFS AND NAM TSECTIONS SUGGEST SOMETIME DURING
THE AFTN...THE POSSIBILITY OF LOW TOPPED SHOWERS.

OUTLOOK...

SATURDAY NIGHT...IFR CONDS PROBABLE LATER ON WITH STRATUS/FOG DEVELOPMENT
OVERNIGHT SATURDAY/SUNDAY MORNING. THERE IS POTENTIAL FOR PATCHY LIFR
CONDITIONS IN DENSE FOG/STRATUS BY DAYBREAK SUNDAY. LIGHT WIND.

SUNDAY-SUNDAY NIGHT...LOWER CONDITIONS POSSIBLE IN THE MORNING THE
BECOMING VFR DURING THE DAY. A COLD FRONT APPROACHES LATE IN THE DAY
INTO SUNDAY NIGHT WITH SCATTERED SHOWERS/THUNDERSTORMS AND LOWER
CONDITIONS POSSIBLE.

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

&&

.MARINE...
BUOYS 44025 AND 44009 HAVE BEEN RESTORED TO SERVICE. THE COMPLETE
RESTORATION OF BUOY 44009 MAY BE DELAYED TIL JANUARY 2015?

EAST WINDS WILL PROBABLY BE BLOWING AT 15 KT ON SATURDAY. SEAS
WILL PROBABLY BE 4 TO 5 FT THROUGH SATURDAY

THE EXCEPTION WE WILL CANCEL THE FAR NNJ WATERS PORTION OF THE
ADVY BY 930 PM TONIGHT.

CONFIDENCE ON THE OVERALL SEAS AND WIND SCENARIO IS A BIT BELOW
AVERAGE.

OUTLOOK...

SATURDAY NIGHT-SUNDAY...SMALL CRAFT ADVISORY EXTENDED AS SEAS
LOOK TO LINGER INTO EARLY SATURDAY NIGHT BEFORE SUBSIDING LATER IN
THE NIGHT INTO SUNDAY.

SUNDAY NIGHT...A COLD FRONT APPROACHES SUNDAY NIGHT WITH SHOWERS AND
POSSIBLY THUNDERSTORMS WITH INCREASING WINDS. WINDS AND WAVES MAY
APPROACH SMALL CRAFT ADVISORY LEVELS BEHIND THE COLD FRONT OVERNIGHT
INTO EARLY MONDAY MORNING..

MONDAY-WEDNESDAY...CONDITIONS EXPECTED TO TO DROP BELOW ADVISORY
LEVELS DURING THE DAY MONDAY AND STAY BELOW THROUGH WEDNESDAY.

&&

.RIP CURRENTS...
WE CONTINUED THE MDT RISK FOR FOR THE FORMATION OF DANGEROUS RIP
CURRENTS ON SATURDAY FOR NJ. WE ARE USING 4 FT 7 SECONDS. THIS
FORECAST FOR SATURDAY MAY NEED FURTHER ADJUSTMENT.

&&

.PHI WATCHES/WARNINGS/ADVISORIES...
PA...NONE.
NJ...NONE.
DE...NONE.
MD...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 2 AM EDT SUNDAY FOR ANZ451>455.
     SMALL CRAFT ADVISORY UNTIL 2 AM EDT SATURDAY FOR ANZ450.

&&

$$
SYNOPSIS...ROBERTSON
NEAR TERM...DRAG 909
SHORT TERM...DRAG/KLEIN
LONG TERM...DRAG/ROBERTSON
AVIATION...DRAG/ROBERTSON 909
MARINE...DRAG/ROBERTSON 909
RIP CURRENTS...






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