Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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000 FXUS61 KPHI 301851 AFDPHI AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MOUNT HOLLY NJ 251 PM EDT SUN AUG 30 2015 .SYNOPSIS... A WEAKENING COLD FRONT WILL ARRIVE TONIGHT, OTHERWISE HIGH PRESSURE WILL REMAIN MOSTLY CENTERED NEAR THE MID ATLANTIC REGION THROUGH MUCH OF THIS WEEK. HOWEVER, A WEAK COLD FRONT SHOULD SLIDE SOUTH THROUGH OUR REGION THURSDAY NIGHT OR FRIDAY. AN OFFSHORE LOW AND HIGH PRESSURE TO OUR NORTHEAST WILL PROBABLY PROVIDE SOMEWHAT COOLER TEMPERATURES NEXT FRIDAY INTO THE WEEKEND. && .NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
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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.
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&& .SHORT TERM /6 AM MONDAY MORNING THROUGH 6 PM MONDAY/...
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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.
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&& .LONG TERM /MONDAY NIGHT THROUGH SATURDAY/... DRAFT: TO BE UPDATED AT 330 PM. 500 MB: A STRONG WARM RIDGE OF HIGH PRESSURE WILL PREVAIL ALONG THE EAST COAST THROUGH 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 AND SO AN ASSOCIATED BOUNDARY SLIPS SOUTHWARD. 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. THURSDAY THROUGH SUNDAY SHOULD STILL AVERAGE 5 DEGREES OR MORE ABOVE NORMAL. 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. FORECAST BASIS: UNLESS OTHERWISE NOTED, 12Z/30 GFS MOS WAS THE PRIMARY GUIDANCE MONDAY NIGHT-TUESDAY NIGHT, 12Z/30 MEX MOS WEDNESDAY AND WEDNESDAY NIGHT, THEN THE 1521Z/30 WPC GRIDDED ELEMENTS OF MAX/MIN TEMP, 12 HOUR POP, 6 HOUR DEWPOINT-SKY-WIND FROM THURSDAY ONWARD. 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. IT IS POSSIBLE THE I-95 CORRIDOR COULD SEE AN EXTENDED HEAT WAVE BEYOND 4 DAYS. MAX HEAT INDEX VALUES IN THIS HEAT WAVE SO FAR ARE FORECAST TO BE IN THE MID TO UPPER 90S. 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 OF NW NJ AND E PA. LIGHT WINDS TEND TO BE NW DURING EACH AFTERNOON. SMALL CHC OF CONVECTION E PA AND NNJ WED AFTN AND THU AFTN BUT MAY BE TOO LITTLE TO MENTION IN OUR 330 PM FCST. STILL UNDECIDED. 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 I-80 NORTHWARD. NEXT WEEKEND...FAIR AND VERY WARM. SLIGHT CHANCE FOR AFTN/EVENING CONVECTION POCONOS TO THE LEHIGH VALLEY AND KRDG BUT AGAIN PROBABLY TOO SMALL A POP TO MENTION. OVERALL CONFIDENCE THESE NEXT 6 DAYS: ABOVE AVERAGE. && .AVIATION /19Z SUNDAY THROUGH FRIDAY/...
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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... DRAFT: WILL UPDATE AT 330 PM. 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...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.
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&& .MARINE...
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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... DRAFT: TO BE UPDATED AT 330 PM. 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 DEVELOP BUT ATTM, BELOW SCA CRITERIA.
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&& .RIP CURRENTS...
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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, POSSIBLY TO MODERATE NEXT WEEKEND OR MONDAY DEPENDING ON THE EVENTUAL DEVELOPMENT OF OFFSHORE LOW PRESSURE AND ITS WESTWARD SWEEPING SWELLS.
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&& .CLIMATE... THIS SECTION WILL PROBABLY DISCARD LATER 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. 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 && .PHI WATCHES/WARNINGS/ADVISORIES... PA...NONE. NJ...NONE. DE...NONE. MD...NONE. MARINE...NONE. && $$ SYNOPSIS...GORSE/JOHNSON NEAR TERM...GORSE SHORT TERM...GORSE LONG TERM...DRAG AVIATION...DRAG/GORSE/JOHNSON MARINE...DRAG/GORSE/JOHNSON RIP CURRENTS...DRAG/GORSE CLIMATE...DRAG

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