Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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000
FXUS61 KPHI 290856
AFDPHI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
456 AM EDT MON SEP 29 2014

.SYNOPSIS...
WEAK HIGH PRESSURE RESIDES OVER THE AREA TODAY. LOW PRESSURE OVER
THE EASTERN GREAT LAKES TONIGHT WILL MOVE ACROSS PENNSYLVANIA
TUESDAY WHILE A WEAK COLD FRONT SLIDES SOUTH ACROSS THE REGION.
THAT LOW PRESSURE SYSTEM WILL DEVELOP OUT TO SEA WEDNESDAY WITH
HIGH PRESSURE IN EASTERN CANADA RIDGING DOWN INTO THE MID ATLANTIC
STATES THURSDAY. A STRONGER COLD FRONT WILL MOVE EAST ACROSS THE
MID ATLANTIC STATES EARLY SATURDAY. WEAK HIGH PRESSURE FOLLOWS
NEXT SUNDAY.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
QUIET WEATHER CONTINUES ACROSS THE REGION TODAY. WEAK HIGH PRESSURE
REMAIN OFFSHORE WHILE A WEAK LOW MOVES ACROSS THE GREAT LAKES AREA.
AN UPPER TROUGH WILL MOVE TOWARD THE AREA ALSO...CREATING A BKN-OVC
SKY OF HIGH CI/CS CLOUDS. TEMPERATURES TODAY WILL BE A FEW DEGREES
COOLER THAN SUNDAY...BUT STILL ABOVE NORMAL FOR THE CLOSING DAYS OF
SEPTEMBER. READINGS WILL RANGE FROM THE UPPER 70S TO LOW 80S IN MOST
AREAS AND A FEW LOW/MID 70S ACROSS THE HIGHER ELEVATIONS ACROSS THE
NORTH. WINDS WILL REMAIN LIGHT...MOSTLY WEST OR SOUTHWEST.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 AM TUESDAY/...
THE UPPER TROUGH WILL CROSS THE AREA TONIGHT WHILE A WEAK SFC LOW
MOVES INTO NY STATE. THERE WILL STILL BE PLENTY OF UPPER MOISTURE
ACROSS THE AREA...BUT NO PCPN IS EXPECTED WITH THE LOWER PARTS OF
THE ATMOSPHERE EXPECTED TO REMAIN DRY. LOW TEMPERATURES TONIGHT
WILL CONTINUE 5 TO 7 DEGREES ABOVE NORMAL...WITH LOWS IN THE LOW
60S OVER METRO PHILADELPHIA...TO THE MID/UPPER 50S ELSEWHERE.
WINDS WILL CONTINUE TO BE LIGHT.

&&

.LONG TERM /TUESDAY THROUGH SUNDAY/...
500 MB: A RATHER STRONG CLOSED LOW SHORT WAVE MOVING SOUTHEAST FROM
THE EASTERN GREAT LAKES TUESDAY WILL CROSS SOUTHERN NEW ENGLAND
WEDNESDAY THEN SLOWLY DEPART EAST OF NEW ENGLAND THURSDAY. A HIGH
AMPLITUDE TROUGH OVER CENTRAL NORTH AMERICA FRIDAY WILL SEND ONE
OF ITS SHORT WAVES ACROSS THE NORTHEAST SATURDAY THEN THE CYCLONIC
FLOW PROBABLY FLATTENS OUT SUNDAY.

TEMPERATURES: SEPTEMBER WILL PROBABLY AVERAGE CLOSE TO 1.5 DEGREES
ABOVE NORMAL. CALENDAR DAY TEMPERATURES SHOULD AVERAGE 5 TO 8 DEGREES
ABOVE NORMAL TUESDAY THROUGH FRIDAY THEN COOL TO SLIGHTLY BELOW NORMAL
BY SUNDAY.

FORECAST BASIS: UNLESS OTHERWISE NOTED THE LONG TERM PERIOD OF THIS
FORECAST IS GENERALLY BASED ON A 50 50 BLEND OF THE 00Z/29 NAM/GFS
MOS FOR THE PERIOD TUESDAY-WEDNESDAY...THE 00Z/29 GFS MOS WEDNESDAY
NIGHT-THURSDAY...THEN THEREAFTER (THURSDAY NIGHT ONWARD) THE
0522Z/29 WPC GRIDDED GUIDANCE. ALL THIS IS EVENTUALLY CHECKED
AGAINST THE 00Z/29 ECMWF TO SEE IF WE`RE IN THE BALLPARK WITH
ECMWF CYCLICALLY PERSISTENT 18Z 2 METER TEMPERATURES.
PRECIPITATION PROBABILITY GUIDANCE IS CHECKED AGAINST THE 21Z/28
SREF 3HRLY POPS FOR .01 THROUGH 00Z SATURDAY AND THEREAFTER THE
00Z/29 GEFS 6HR POPS FOR 0.05.

THE DAILIES...

MODEL AMPLITUDE AND TRACK STILL DIFFER ON THE MIDWEEK CLOSED LOW
SHORT WAVE BUT OVERALL...ENOUGH AGREEMENT EXISTS TO EXPRESS AVERAGE
CONFIDENCE IN THE FORECAST DETAILS FOR THIS LONG TERM PERIOD.

WE`RE COUNTING ON PROGRESSIVE AND NOT COUNTING ON AN EXTENDED
PERIOD OF INVERTED TROF HANG BACK ALA THE 00Z/29 NAM.

TUESDAY-WEDNESDAY...MODEL GUIDANCE IS COMING AROUND TO FAVORING ENOUGH
STRENGTH/POTENCY IN THE SHORT WAVE DRIVING SEWD FROM THE GREAT
LAKES TO MAKE ITS OWN SFC LOW PRESSURE AND SEND IT FROM ROUGHLY
TORONTO TOMORROW MORNING THROUGH PA TUESDAY AFTERNOON AND THEN
EVENTUALLY OFFSHORE MIDWEEK.

THE COMBINATION OF THE SOUTHWARD MOVING BACKDOOR COOL FRONT...DEEP
AND LIGHT E-SE FLOW NORTH OF THE BOUNDARY (I78 REGION
NORTHWARD)...PWAT OF 1.25 INCHES...ELEVATED INSTABILITY WITH SWI
SUBZERO AND THE STRONG SHORT WAVE PASSAGE SHOULD PERMIT SLOW
MOVING SHOWERY RAINS TO DEVELOP IN E PA AND THE NORTHERN HALF OF
NJ TUESDAY AND TAPER OFF WEDNESDAY. WHILE SOME AREAS WILL MISS THE
RAIN...OTHERS COULD EASILY SEE AN INCH.

ITS BOTHERSOME THAT THE NAM AND ECMWF HAVE BEEN AT TIMES ADVERTISING
2-5 INCHES OF RAIN FROM NNJ TO S OF LI THE PAST 48 HOURS OF CYCLES. THE
IMPLIED MESSAGE...SLOW MOVERS CAN BE DECENT RAIN PRODUCERS. THUNDER
IS IN THE GRIDS NOW FROM NW NJ INTO E PA LATE TUE AFTN/EVENING.

THE PRIMARY FAVORED WINDOW OF OPPORTUNITY FOR NEEDED RAINFALL N OF
I78 IS 21Z TUE-18Z WED.

S OF I78...ESPECIALLY THE DELMARVA AND FAR SE PA...VARIABLE
CLOUDINESS THROUGH THE PERIOD WITH CHANCE OF A SHOWER BUT NOT
NEARLY AS THREATENING AS FURTHER NORTH.

PATCHY FOG POSSIBLE EARLY TUESDAY AND EARLY WEDNESDAY MORNINGS.


THURSDAY...PROBABLY DRYING OUT IN DEVELOPING NNW FLOW ENTIRE
REGION AS THE CLOSED LOW SHIFTS TO THE E OF NEW ENGLAND AND
HEIGHTS WARM WITH THE RIDGE ARRIVING BEHIND THE DEPARTING CLOSED
LOW ALOFT. PATCHY FOG POSSIBLE EARLY THU

FRIDAY-EARLY SATURDAY...PATCHY FOG POSSIBLE EARLY FRIDAY THEN DRY
PROBABLY MOST OF FRIDAY WITH A PERIOD OF SHOWERS PROBABLE AT NIGHT
OR EARLY SATURDAY AS A COLD FRONT ARRIVES...ASSOCIATED WITH THE
HIGH AMPLITUDE TROUGH AXISED SOUTHWARD FROM THE GREAT LAKES.

LATER SATURDAY-SUNDAY...DRIES OUT WITH A GUSTY WESTERLY WIND.
COOLER THAN NORMAL FOR A SHORT TIME BEFORE THE NEXT BRIEF
WARMING CYCLE!

&&

.AVIATION /09Z MONDAY THROUGH FRIDAY/...
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG,
KMIV, KACY AND SURROUNDING AREAS.

MORNING FOG WITH LOCALLY MVFR OR PERHAPS SOME HIGH IFR VSBYS
POSSIBLE...BUT OTHER THAN THAT...ANOTHER GOOD FLYING WEATHER DAY ON
TAP. THERE WILL BE MOSTLY BKN-OVC CI/CS CLOUDS STREAMING OVERHEAD
MUCH OF THE DAY...BUT WITH RATHER LIGHT WINDS...CONDITIONS WILL BE
GOOD. WEAK HIGH PRESSURE REMAINS ACROSS THE AREA...WHILE AN WEAK
UPPER TROUGH APPROACHES FROM THE WEST. VFR EXPECTED INTO
TONIGHT...WITH MORE LOCALIZED FOG POSSIBLE.

OUTLOOK...
TUESDAY...MAINLY VFR CIGS WITH POSSIBLE MVFR CONDS IN PATCHY FOG
NEAR SUNRISE TUESDAY AND THEN AGAIN IN AFTN SHOWERS...ESPECIALLY
KABE AND KRDG. SLIGHT CHC OF A LATE DAY TSTM THERE. LIGHT WIND
TRENDING EASTERLY MOST TAF SITES DURING THE AFTERNOON WITH MAX
GUST 10-15KT.

WEDNESDAY...MAINLY VFR CIGS WITH POSSIBLE MVFR CONDS IN SHOWERS
KABE/KRDG/KTTN DURING THE MORNING. E/NE WINDS GUST 15 KNOTS.

THURSDAY...POSSIBLE MVFR FOG EARLY OTHERWISE VFR SCT-BKN CLOUDS
AOA 4000 FT. N-NW WIND GUST 15 KT.

FRIDAY...VFR CIGS EXCEPT POSSIBLE MVFR CONDS 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.

&&

.MARINE...
QUIET CONDITIONS CONTINUE ON THE WATERS. WEAK HIGH PRESSURE REMAIN
OFFSHORE AND A WEAK LOW WILL DEVELOP ACROSS THE GREAT LAKES TONIGHT
AND MOVE INTO NY STATE TUE. A LIGHT...MOSTLY SWRLY...FLOW WILL BE
ACROSS THE WATERS. WINDS MAY TURN ERLY LATE TONIGHT. WIND SPEEDS
UNDER 10 KNOTS EXPECTED. PARTLY/MOSTLY SUNNY TODAY AND PARTLY CLOUDY
TONIGHT. SEAS AROUND 2 FT ON THE OCEAN AND 1 TO 2 FT OVER DEL BAY.

OUTLOOK...
TUESDAY: WINDS AND SEAS INCREASE WITH DEVELOPING EAST-NORTHEAST FLOW
BUT SHOULD REMAIN BELOW SCA CRITERIA.

TUESDAY NIGHT THROUGH WEDNESDAY NIGHT: NE FLOW TUESDAY NIGHT THROUGH
WEDNESDAY NIGHT SHOULD INCREASE TO SCA CRITERIA ALONG THE NNJ COAST
TUESDAY NIGHT AND THEN POSSIBLY SOUTHWARD TO THE ENTIRE ATLC COAST LATER
WEDNESDAY OR WEDNESDAY NIGHT. DELAWARE BAY MAY NOT SEE WIND GUSTS
ABOVE 22 KT WITH ANY SCA HEADLINE THERE NOT LIKELY AS OF THIS WRITING.

THURSDAY...SMALL CHANCE OF SCA SEAS ON THE ATLANTIC WATERS FROM NE
SWELLS GENERATED BY AN OFFSHORE LOW.

FRIDAY...WIND BECOMING SOUTH BY NIGHT. SMALL CHANCE OF AN SCA AT
NIGHT.

&&

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

&&

$$
SYNOPSIS...DRAG 455
NEAR TERM...O`HARA
SHORT TERM...O`HARA
LONG TERM...DRAG 455
AVIATION...DRAG/O`HARA 455
MARINE...DRAG/O`HARA 455







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