Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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FXUS61 KPHI 302025
AFDPHI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
425 PM EDT SUN AUG 30 2015

.SYNOPSIS...
A WEAKENING COLD FRONT WILL ARRIVE TONIGHT, OTHERWISE HIGH PRESSURE
WILL REMAIN CENTERED MAINLY NEAR THE MID ATLANTIC REGION THROUGH
MUCH OF THIS WEEK. A WEAK COLD FRONT SHOULD SLIDE SOUTH THROUGH
OUR REGION THURSDAY NIGHT OR FRIDAY. THEREAFTER, HIGH PRESSURE
WILL RESIDE ALONG THE EASTERN NEW ENGLAND COAST THROUGH SUNDAY,
PROBABLY PROVIDING A LITTLE RELIEF FROM THE HEAT THIS COMING
WEEKEND.

&&

.NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
A SHORT WAVE TROUGH WILL ARRIVE INTO THE NORTHEAST TONIGHT AND AS IT
DOES IT SHOULD TEND TO WEAKEN. A WEAK COLD FRONT AT THE SURFACE IS
TIED TO THIS FEATURE, AND WITH SOME INCREASE IN MOISTURE SOME
SHOWERS AND A THUNDERSTORM ARE ONGOING NEAR OR IN OUR NORTHWESTERN
ZONES. THE OVERALL LIFT, SHEAR AND INSTABILITY LOOKS WEAK ENOUGH TO
KEEP ANY CONVECTIVE CORES FROM GETTING TO ROBUST. THE INITIATION
EARLY ON APPEARED TO BE DRIVEN BY TERRAIN IN NORTHEASTERN
PENNSYLVANIA, AND VISIBLE SATELLITE IMAGERY THIS AFTERNOON SHOWS THE
MAIN CUMULUS DEVELOPMENT MAINLY OVER THE HIGHER TERRAIN. THE FLOW
BELOW ABOUT 10000 FEET IS 15 KNOTS OR LESS, THEREFORE THIS ACTIVITY
WILL SLOWLY SHIFT EASTWARD THROUGH THIS EVENING ALTHOUGH IT SHOULD
TEND TO WEAKEN WITH AN EASTERN AND SOUTHERN EXTENT. A FEW LOCALES
WILL GET SOME NEEDED RAIN IN THE FORM OF DOWNPOURS.

WE THEREFORE KEPT LOW POPS POPS GOING FOR A TIME THROUGH EARLY TO
MID EVENING, ALTHOUGH INCREASED THEM A BIT ACROSS THE NORTHWEST
ZONES INTO THIS EVENING GIVEN ADDITIONAL DEVELOPMENT TO OUR WEST.
SOME GUIDANCE WANTS TO HANG ONTO SOME ISOLATED ACTIVITY OVERNIGHT,
HOWEVER THAT MAY BE OVERDONE. OTHERWISE, AREAS OF MID TO HIGH LEVEL
CLOUDINESS WILL MOVE ACROSS THE AREA DUE TO THE INCOMING SHORT WAVE
TROUGH AND ALSO A NORTHERN JET STREAK PULLING NORTHWARD MOISTURE
FROM AN THE UPPER-LEVEL LOW ACROSS THE EASTERN GULF COAST.

IT WILL BE A WARMER NIGHT ACROSS MUCH OF THE AREA AS THE DEW POINTS
TEND TO HANG NEAR THE MUGGY LEVEL. SOME FASTER COOLING THIS EVENING
THOUGH SHOULD OCCUR MAINLY ALONG THE COAST WITH A SEA BREEZE, WHICH
WILL WEAKEN. AS FOR THE LOW TEMPERATURES, WE USED A MOS BLEND THEN
MADE SOME LOCAL TWEAKS.

&&

.SHORT TERM /6 AM MONDAY MORNING THROUGH 6 PM MONDAY/...
AN UPPER-LEVEL TROUGH IS FORECAST TO AMPLIFY SOME ACROSS NEW ENGLAND
ON MONDAY. THE SOUTHWESTERN EXTENT OF THIS FEATURE REACHES INTO THE
MID ATLANTIC REGION. THIS PROVIDES SOME CYCLONIC FLOW ALOFT, WHILE
AT THE SURFACE WEAK HIGH PRESSURE GENERALLY REMAINS NEARBY. A WEAK
SURFACE FRONT OR TROUGH LOOKS TO BE DRAPED ACROSS OUR AREA, AND
WHILE A SHOWER OR THUNDERSTORM CANNOT BE RULED OUT THIS IS OF LOW
CONFIDENCE. THE MODEL GUIDANCE OVERALL DOES NOT HAVE A STRONG SIGNAL
FOR CONVECTIVE DEVELOPMENT, AND SINCE THE CHC LOOKS RATHER LOW WE
OPTED TO LEAVE OUT ANY MENTION ATTM. IT IS POSSIBLE A FEW ISOLATED
CELLS ARE AROUND TO START THE DAY AS SOME FORECAST SOUNDINGS DO SHOW
SOME INCREASE IN MID LEVEL INSTABILITY AROUND DAYBREAK.

OTHERWISE, A DECENT AMOUNT OF MID TO HIGH LEVEL CLOUDS SHOULD BE
AROUND WHICH WILL COMBINE WITH SOME CUMULUS DEVELOPMENT. A RATHER
WARM TO HOT AFTERNOON IS EXPECTED GIVEN THE SOUTHWESTERLY FLOW AND
ANY NOTABLE COOLING ALOFT IS MOSTLY ACROSS NEW ENGLAND. AS A RESULT,
WE LEANED CLOSER TO THE WARMER GFS MOS FOR MOST PLACES REGARDING
HIGH TEMPERATURES.

&&

.LONG TERM /MONDAY NIGHT THROUGH SUNDAY/...
500 MB: IN GENERAL, A FAIRLY STRONG SUMMER RIDGE OF HIGH PRESSURE
WILL PREVAIL ALONG THE EAST COAST THROUGH NEXT SUNDAY WITH ONLY A
MINOR WEAKENING OF THIS RIDGE OVER OUR AREA LATE WEDNESDAY INTO
FRIDAY, AS A STRONG SHORT WAVE DIVES SEWD TOWARD THE MARITIMES
(55N/55W). THAT PERMITS A LITTLE MORE NORTHERLY COMPONENT ALOFT
LATE THIS COMING WORKWEEK AND SO AN ASSOCIATED SURFACE BOUNDARY
SLIPS SOUTHWARD. ITS COOLING EFFECTIVENESS FELT PRIMARILY ON THE
COASTAL PLAIN.

TEMPERATURES: AUGUST THROUGH THE 29TH WAS AVERAGING NEAR OR ABOVE
NORMAL. KMPO AND KGED WERE THE ONLY TWO OF THE 8 CLIMATE SITES
BELOW NORMAL. KTTN KACY AND KPHL WERE AVERAGING ~1 TO ~2F ABOVE
NORMAL AND WILL WARM THESE LAST TWO DAYS OF THE MONTH.

CALENDAR DAY DEPARTURES TUESDAY THROUGH THURSDAY WILL BE 6 TO 12
DEGREES ABOVE NORMAL WITH THE LARGEST POSITIVE DEPARTURES N AND NW
OF KPHL OVER E PA AND THE NORTHWEST HALF OF NJ. THEREAFTER, FRIDAY
THROUGH SUNDAY SHOULD STILL AVERAGE 5 DEGREES OR MORE ABOVE
NORMAL, POSSIBLY STILL 10 DEGREES ABOVE, ESPECIALLY NW OF I-95.
HOW MUCH COOLING OCCURS FRIDAY AND BEYOND IS DEPENDENT ON THE
STRENGTH OF ONSHORE FLOW. IT APPEARS THE GREATEST IMPACT OF
COOLING ONSHORE FLOW WILL BE THE SOUTHERN NJ AND DE COASTS.
SST`S ARE WELL ABOVE AVERAGE SO THE COOLING EFFECTIVENESS IS LESS.


FORECAST BASIS: UNLESS OTHERWISE NOTED, 12Z/30 GFS MOS WAS THE
PRIMARY GUIDANCE MONDAY NIGHT-TUESDAY NIGHT, 12Z/30 MEX MOS
WEDNESDAY THROUGH THURSDAY, THEN THE 1521Z/30 WPC GRIDDED
ELEMENTS OF MAX/MIN TEMP, 12 HOUR POP, 6 HOUR DEWPOINT- SKY-WIND
FROM THURSDAY NIGHT ONWARD. THE EXCEPTION HERE...WAS MEX AND WPC
MIN TEMPS WERE BLENDED 50 50 FRI NIGHT AND SAT NIGHT.

HAZARDS...

A HEAT WAVE WILL BE IN PROGRESS THROUGH THURSDAY FOR THE I-95
CORRIDOR EASTWARD TO NEAR THE COASTS, ITS DURATION SHOULD BE AT
LEAST 4 DAYS WHETHER OR NOT IT BEGINS THIS AFTERNOON OR MONDAY.
THE QUESTION, DOES IT BREAK ANYTIME FRIDAY-SUNDAY OR JUST GO ON
AND ON THROUGH EARLY NEXT WEEK IN THE INTERIOR NEAR AND NW OF I-95.
IT IS POSSIBLE THE I-95 CORRIDOR COULD SEE AN EXTENDED HEAT WAVE
BEYOND 6 DAYS (TODAY-SUNDAY THROUGH THURSDAY LOOK SOLID FOR 90-95F
AND FRIDAY LOOKS LIKE A BETTER THAN EVEN CHANCE OF 90 PLUS). MAX
HEAT INDEX VALUES IN THIS HEAT WAVE SO FAR ARE FORECAST TO BE IN
THE MID TO UPPER 90S. THERE IS A SLIM CHANCE WE WILL NEED A HEAT
ADVISORY FOR THE URBAN CORRIDOR EITHER OF ANY THREE AFTERNOONS
BETWEEN THIS COMING WEDNESDAY AND FRIDAY.

THUNDERSTORM DRENCHING RAINS? NEAR THE COOL FRONT FRIDAY BUT OVERALL
AS PER WPC, THE DRY SPELL IS GOING TO LAST QUITE AWHILE, POSSIBLY
THROUGH THE START OF LABOR DAY WEEK.

THE DAILIES...

MONDAY NIGHT-THURSDAY...FAIR AND HOT AFTERNOONS WITH PATCHY FOG
POSSIBLE LATE AT NIGHT OVER THE COUNTRYSIDE, MAINLY NW NJ AND E
PA. LIGHT WINDS TEND TO BE W-NW DURING EACH AFTERNOON. SMALL CHC
OF CONVECTION E PA AND NNJ WED AFTN AND THU AFTN PER INSTABILITY
INDICATORS INCLUDING KI.

THU NIGHT-FRIDAY...A SWD MOVING COLD FRONT MAY SPAWN HEAVY SOUTHWARD
MOVING CONVECTION BUT ONLY IN A PWAT OF 1.6 INCHES. SLOW MOVERS-
GULLY WASHERS WHERE THEY OCCUR BUT LITTLE PREDICTABILITY ATTM EXCEPT
MOST OF THE ACTIVITY SHOULD REMAIN JUST INLAND.  POTENTIALLY STILL
90F VCNTY KPHL SWWD AND WESTWARD ON FRIDAY. DEWPOINTS HIGHER,
AROUND 70F AND 1400J ML CAPE. 0-6KM BULK SHEAR IS POOR FOR ANY
SVR. STRATUS FOG POTENTIAL AT NIGHT AND IN THE MORNING, ESPECIALLY I-80
NORTHWARD.

NEXT WEEKEND...FAIR AND VERY WARM. SLIGHT CHANCE FOR AFTN/EVENING
CONVECTION POCONOS TO THE LEHIGH VALLEY AND KRDG PER ECMWF KI AND
A TENDENCY FOR UPSLOPE FLOW-LIFT.

OVERALL CONFIDENCE THESE NEXT 6 DAYS: ABOVE AVERAGE.

&&

.AVIATION /21Z SUNDAY THROUGH FRIDAY/...
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY AND SURROUNDING AREAS.

REST OF THIS AFTERNOON...VFR WITH SOME CUMULUS AROUND 5000 FEET,
ALONG WITH MID TO HIGH LEVEL CLOUDS MOVING THROUGH. SOUTHWESTERLY
WINDS UP TO 10 KNOTS, WHICH SHOULD TURN MORE SOUTHERLY AT KACY AND
KILG DUE TO A SEA/BAY BREEZE. A FEW SHOWERS AND A THUNDERSTORM
WILL BE NEAR THE KABE TO KRDG AREAS BY LATE AFTERNOON.

TONIGHT...VFR OVERALL. A WEAKENING COLD FRONT SHOULD ALLOW A SHOWER
OR THUNDERSTORM TO ARRIVE MAINLY NEAR THE KABE AND KRDG AREAS THIS
EVENING, HOWEVER COVERAGE IS EXPECTED TO BE LOW. SOUTHWESTERLY WINDS
5-10 KNOTS, BECOMING LIGHT AND VARIABLE AT MANY OF THE TERMINALS.

MONDAY...LOCALIZED MVFR DUE TO FOG IS POSSIBLE EARLY, OTHERWISE VFR.
WHILE A SHOWER OR THUNDERSTORM IS POSSIBLE, THE CHANCE APPEARS TO BE
RATHER LOW AT THIS TIME. LIGHT SOUTHWESTERLY WINDS INCREASING TO
AROUND 10 KNOTS.

OUTLOOK...
MONDAY NIGHT THROUGH WEDNESDAY...VFR CONDITIONS EXPECTED THOUGH
LOCALIZED MVFR/IFR CONDITIONS WITH FOG/ST POSSIBLE EACH MORNING,
MAINLY NEAR KABE-KRDG. LIGHT WIND, TENDS BE NW EACH AFTERNOON.

THURSDAY...MOSTLY VFR CONDITIONS. ISOLATED THUNDERSTORMS POSSIBLE
LATE.  IFR CIGS/VSBY POSSIBLE N OF I-80 LATE THU NIGHT.

FRIDAY...MOSTLY VFR WITH BRIEF IFR CONDS POSSIBLE IN TSTMS. MVFR
OR IFR CIGS DEVELOPING IN NELY FLOW NEAR AND N OF I-80 WITH
POSSIBLE IFR VSBY IN FOG AT NIGHT.

OVERALL LONG TERM AVIATION FCST CONFIDENCE: ABOVE AVERAGE.

&&

.MARINE...
THE CONDITIONS ARE ANTICIPATED TO REMAIN BELOW SMALL CRAFT ADVISORY
CRITERIA THROUGH MONDAY. HIGH PRESSURE GENERALLY REMAINS NEAR THE
MID ATLANTIC WHICH WILL KEEP A SOUTHWESTERLY FLOW ACROSS OUR AREA.
AN INCREASE INTO THIS EVENING IS EXPECTED DUE TO MIXING AND A SEA
BREEZE CIRCULATION, AND GUSTS TO 20 KNOTS ARE POSSIBLE. THE SEAS
OVERALL ARE ANTICIPATED TO BE IN THE 1 TO 3 FOOT RANGE ACROSS OUR
WATERS.

OUTLOOK...
MONDAY NIGHT THROUGH THURSDAY...WINDS AND SEAS SHOULD STAY WELL
BELOW SMALL CRAFT ADVISORY CRITERIA. WATER TEMPERATURES ARE ABOVE
NORMAL.

FRIDAY...ATLC SEAS MAY INCREASE AS AN EASTERLY FLOW DEVELOPS BUT
ATTM, BELOW SCA CRITERIA.

&&

.RIP CURRENTS...
A LONG PERIOD EAST TO SOUTHEAST SWELL, 10-11 SECONDS, CONTINUES TO
ROLL IN ALONG THE COAST. THIS COMBINED WITH INCREASED SOUTHERLY
WINDS WILL RESULT IN TRICKY CONDITIONS AT TIMES WITHIN THE SURF ZONE
ESPECIALLY DURING TIDE CHANGES. AS A RESULT THERE IS A MODERATE RISK
FOR THE DEVELOPMENT OF DANGEROUS RIP CURRENTS THROUGH THIS EVENING
ALONG THE NEW JERSEY SHORE AND THE DELAWARE BEACHES.

THE OUTLOOK IS FOR GENERALLY LOW ENHANCED CONDITIONS THIS WEEK WITH
A SLIGHTLY SUBSIDING 1-2 FOOT 10 SECOND SE SWELL. ITS POSSIBLE WE
WILL STILL NEED TO CARRY A MDT RISK ON MONDAY BASED ON THE VERY SLOW
TO SUBSIDE SWELL OF TODAY-SUNDAY.

NEXT FRIDAY ONWARD MAY SEE THE RISK INCREASE, WITH A CHANCE OF MODERATE
NEXT WEEKEND OR LABOR DAY DEPENDING ON THE EVENTUAL DEVELOPMENT
OF OFFSHORE LOW PRESSURE AND ITS WESTWARD SWEEPING SWELLS. LOTS OF
UNCERTAINTY NEXT WEEKEND.

IN THE MEANTIME, SWIM SAFELY WITHIN THE WATCHFUL SAFETY VIEW OF
OUR BEACH PATROLS.

&&

.CLIMATE...
THIS SECTION MAY BE DISCARDED TONIGHT.

AUGUST: KPHL (POR 1872) AND KACY (POR 1874), BARRING ANY MORE RAIN
THIS MONTH, WILL BE 10TH DRIEST ON RECORD WITH 0.98 AND 1.25"
RESPECTIVELY. THE KILG 1.54 INCHES IS 13TH DRIEST ON RECORD
PROVIDED NO MORE RAIN FALLS BEFORE 1 AM TUESDAY.

LISTING THE SEASONS 90F OR WARMER DAYS AS INFO FOR YOU TO ADD ONTO
AS THE WEEK PROGRESSES.

THESE TOTALS AS OF THE 29TH AND DO NOT INCLUDE TODAYS 90 PLUS.


KPHL 28, MEAN 21. IF WE ADD 5 MORE DAYS 90F BETWEEN NOW AND SEPT
9 (TOTAL PROJECTED AT LEAST 33) AND KPHL WILL HAVE THE 18TH
HIGHEST SEASONAL TOTAL OF 90 OR HIGHER. POR TO 1872

KABE 12  POR MEAN 17
KACY 16  POR MEAN 10
KILG 11  POR MEAN 20

SAMPLING OF OTHER LOCATION TOTALS FOR 2015 ARE BELOW.
KPNE 30
KVAY 15
KRDG 17
KTTN 20
KGED 18
KFWN 6

RECORDS: NONE POSTED THROUGH THURSDAY. THE RECORDS ARE MORE
VULNERABLE FRIDAY-SUNDAY BUT AT THIS TIME NOT WORTH POSTING.

THE CLOSEST POSSIBLE NEAR RECORD POTENTIAL APPEARS AT KACY ON
WED/THU OF THIS WEEK WITH A 94 IN 1980 ON THE 2ND AND 95 IN 1994
ON THE 3RD. AGAIN, COASTAL SEA BREEZES WILL PROBABLY PRECLUDE.

OTHERWISE MANY RECORDS NEAR 100F WERE ESTABLISHED IN 1953 BETWEEN
AUGUST 31 AND SEPTEMBER 3RD.

&&

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

&&

$$
SYNOPSIS...DRAG/GORSE
NEAR TERM...GORSE
SHORT TERM...GORSE
LONG TERM...DRAG
AVIATION...DRAG/GORSE
MARINE...DRAG/GORSE
RIP CURRENTS...
CLIMATE...COR NEXT TO LAST PGH OF CLIMATE IN RECORDS SECTION



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