Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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000
FXUS61 KPHI 301644
AFDPHI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
1244 PM EDT TUE SEP 30 2014

.SYNOPSIS...
A LOW PRESSURE SYSTEM AND WEAK FRONT WILL AFFECT THE WEATHER TODAY
AND TONIGHT. HIGH PRESSURE WILL BUILD IN WEDNESDAY AND REMAIN THROUGH
FRIDAY. A STRONG COLD FRONT WILL CROSS THE REGION FRIDAY NIGHT INTO
EARLY SATURDAY. HIGH PRESSURE WILL BUILD ACROSS THE AREA SATURDAY
NIGHT INTO EARLY MONDAY. LOW PRESSURE WILL APPROACH FOR LATER
MONDAY AND INTO NEXT TUESDAY.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
WITH THE MIDDAY UPDATE, WE ADJUSTED SKY COVER ACROSS THE REGION TO
REFLECT THE CLEARING SEEN ACROSS A GOOD PORTION OF THE AREA. SOME
SCATTERED CUMULUS IS BEGINNING TO DEVELOP, THOUGH, AS CONVECTIVE
TEMPS ARE BEING MET, AND THIS WILL INCREASE SOME THROUGH THE
AFTERNOON. OTHERWISE WITH REGARDS TO ANY POSSIBLE ISOLATED TO
SCATTERED LATE-DAY SHOWER ACTIVITY, WE TRIMMED IT BACK SOME
THROUGH THE LATE AFTERNOON TO EVENING, BASED ON HRRR GUIDANCE.
HIGHEST CHANCE POPS ARE STILL CONFINED TO THE NORTHWEST PART OF
THE FORECAST AREA. HOURLY TEMPS AND DEWPOINTS WERE TWEAKED USING
THE LAV/LAMP GUIDANCE, AND WE NUDGED MAX TEMPERATURES UP A DEGREE
OR TWO IN A FEW SPOTS.

REST OF TODAY...BETWEEN SHORT WAVES IT SHOULD BE QUIET THROUGH
EARLY AFTERNOON WITH SOME SUNSHINE VSBY AT TIMES THROUGH THE
SCATTERED CLOUDS. AFTERNOON HEATING DEVELOPS SMALL SHOWERS NW OF
I95 WHICH PROBABLY HAVE A TENDENCY TO DRIFT WEST. IF THERE IS TO
BE ANY THUNDER THIS FAR EAST...IT SHOULD BE CONFINED TO THE FAR
WESTERN EDGE OF OUR FCST AREA WESTERN BERKS INTO THE POCONOS.

OVERALL: TEMPS ABOUT 7F WARMER THAN NORMAL AND THE ENTIRE MONTH OF
SEPTEMBER SHOULD AVERAGE ABOUT 1.5 DEGREES ABOVE NORMAL MOST AREAS.

FCST WAS BASED ON A 50 50 BLEND OF THE 00Z/30 GFS/NAM MOS
GUIDANCE.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 AM WEDNESDAY/...
TONIGHT...COOL POOL ALOFT SLIDES EASTWARD ACROSS THE REGION WITH 500MB
TEMPS NEAR -15-16C. BANDS OF SHOWERS MAY BE OCCURRING WITH SUBTLE
LIFT FROM BOTH WEAK BUT DEEP ELY MOIST WINDS NORTH OF I78 AND THE
BACKDOOR COOL FRONT CONVERGENCE ZONE DRIVEN BY THE STRENGTHENING
NE FLOW NE OF THE BACKDOOR CF.

ADDITIONALLY FOG IS LIKELY TO DEVELOP IN THE COOLER BL AIR NE OF
THE FRONTAL BOUNDARY.

TEMPS ABOUT 10F WARMER THAN NORMAL.

FCST WAS BASED ON A 50 50 BLEND OF THE 00Z/30 GFS/NAM MOS
GUIDANCE.

&&

.LONG TERM /WEDNESDAY THROUGH MONDAY/...
THE LAST OF THE UPPER LOW AND WEAK SFC LOW WILL BE EXITING THE
AREA WEDNESDAY. THERE WILL STILL BE ENOUGH RESIDUAL LOW LEVEL
MOISTURE TO PRODUCE SOME SCT SHOWERS...MOSTLY DURING THE FIRST
PART OF THE DAY. WE HAVE RETAINED THE CHC POPS FROM EARLIER. THE
POPS DECREASE DURING THE AFTERNOON FROM W TO E. TEMPERATURES WED
NEAR OR A BIT ABOVE NORMAL...MOSTLY LOW/MID 70S.

WED NIGHT THRU FRI MORNING...MOSTLY DRY WEATHER DURING THIS PERIOD
AS HIGH PRESSURE BUILDS ACROSS THE AREA. PARTLY TO MOSTLY SUNNY
DAYTIME PERIODS AND MOSTLY CLR OVERNIGHTS. TEMPERATURES
AGAIN...NEAR OR A BIT ABOVE NORMAL.

FRI AFTERNOON THRU SATURDAY...A STRONG COLD FRONT WILL CROSS THE
AREA FRI NIGHT INTO EARLY SAT. THE MODELS HAVE BEEN RATHER
CONSISTENT WITH A 6 HR OR SO WINDOW OF QPF CENTERED AROUND FRI
EVENING. WE HAVE UPPER THE POPS TO LIKELY FOR THE EVENING PERIOD
WITH THE EXTRA CONFID IN MULTIPLE/CONSISTENT TRENDS. PROBABILITIES
FOR THUNDER LOOK LOW AT THIS POINT SO WE WILL HOLD ON THAT...SOME
GUSTY WINDS WILL ACCOMPANY THE FROPA HOWEVER. TEMPS WILL DROP BACK
TO BELOW NORMAL SAT WITH DECENT COLD ADVECTION EXPECTED AFTER
FROPA.

SAT NIGHT THRU MONDAY...ANOTHER DRY PERIOD EXPECTED WITH HIGH
PRESSURE BUILDING IN, TEMPERATURES WILL BE BELOW NORMAL
SUNDAY...BUT BACK TO NEAR NORMAL MONDAY. LOWS BOTH SAT AND SUN
NIGHTS WILL FEATURE LOW 40S NORTH RANGING TO THE LOW 50S OVER THE
DELMARVA AND METRO PHILADELPHIA.

&&

.AVIATION /18Z TUESDAY THROUGH SUNDAY/...
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG,
KMIV, KACY AND SURROUNDING AREAS.

REST OF TODAY...MOSTLY SCT- BKN CLOUDS AOA 4000 TO 5000 FT FOR
ALL SITES WITH A POSSIBLE SHOWER VCNTY KRDG/KABE LATE IN THE DAY.
LIGHT SOUTH WIND TURNING E, REMAINING UNDER 10 KNOTS.

TONIGHT...WIND BECOMING NE AT 5-15 KT AND A DECK OF IFR ST/FOG SHOULD
DEVELOP SOUTHWESTWARD FROM LONG ISLAND BEHIND THE BACKDOOR COLD FRONT
CURRENTLY MOVING SW FROM SOUTHERN NEW ENGLAND. CHANCE OF SHOWERS...MAINLY
N OF KPHL.

OUTLOOK...

WEDNESDAY...MOSTLY VFR. SCT SHOWERS WITH SHORT PERIODS OF MVFR
CONDITIONS POSSIBLE. E/NE WINDS WITH GUSTS UP TO 15 KNOTS.

THURSDAY...MORNING FOG WITH LOCAL LOWER CIGS/VSBYS...THEN MOSTLY
VFR. N WIND GUST 15 KT...BECOMING NE LATE.

FRIDAY...VFR CIGS EXCEPT POSSIBLE MVFR CONDITIONS IN ST/FOG EARLY FRIDAY
MORNING AND THEN AGAIN FRIDAY NIGHT IN SHOWERS NEAR A COLD FRONT.
E-SE WIND BECOMING S OR SW LATE AT NIGHT.

SATURDAY...A FEW MORNING SHOWERS EAST...THEN VFR CONDITIONS
EXPECTED.

&&

.MARINE...
NO HEADLINES ATTM.

TODAY...LIGHT WINDS AND SEAS AOB 3 FT TODAY WITH THE S-SW WIND
TURNING TO THE EAST OR NORTHEAST.

TONIGHT...NE WINDS INCREASING WITH GUSTS TO 22 KT LATE AND SEAS
BUILDING TO NEAR 4 FT BY SUNRISE WEDNESDAY. CAPPED SEAS AT 4 FT
THROUGH 8AM WEDNESDAY AS I BELIEVE THE GFS WW3 GUIDANCE IS TOO
SOON TOO HIGH.


OUTLOOK...

WEDNESDAY THRU WED NIGHT: NE FLOW WITH BUILDING WINDS AND SEAS AND SCA
CRITERIA EXPECTED ALONG THE NNJ COAST AND THEN POSSIBLY SOUTHWARD
TO THE ENTIRE ATLANTIC COAST LATER WEDNESDAY OR WEDNESDAY NIGHT.
DELAWARE BAY MAY NOT SEE WIND GUSTS ABOVE 22 KT WITH ANY SCA
HEADLINE THERE NOT LIKELY. HAVE HELD OFF ON ISSUING ANY FORMAL
HEADLINES ON THIS FORECAST UPDATE AS CONDITIONS WILL JUST MEET
LOWER END SCA CRITERIA AND CONFIDENCE IS NOT YET HIGH.

THURSDAY...SMALL CHANCE OF A CONTINUING SCA FLAG SEAS ON THE
ATLANTIC WATERS FROM NE SWELLS GENERATED BY AN OFFSHORE LOW.
CONDITIONS MAY DROP BELOW SCA CRITERIA LATE.

FRIDAY...SOUTH WINDS INCREASING AND BUILDING SEAS. SCA CONDITIONS
A GOOD BET BY AFTERNOON. SHOWERS WITH GUSTY WINDS LATE.

SATURDAY...SCA CONDITIONS EARLY WITH SCT SHOWERS...THEN WINDS AND SEAS
DIMINISHING LATE.

&&

.PHI WATCHES/WARNINGS/ADVISORIES...
PA...NONE.
NJ...NONE.
DE...NONE.
MD...NONE.
MARINE...NONE.

&&

$$
SYNOPSIS...O`HARA
NEAR TERM...DRAG/KLINE
SHORT TERM...DRAG
LONG TERM...O`HARA
AVIATION...DRAG/KLINE/O`HARA
MARINE...DRAG/O`HARA





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