Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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000 FXUS61 KPHI 301723 AFDPHI AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MOUNT HOLLY NJ 123 PM EDT SUN AUG 30 2015 .SYNOPSIS...
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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.
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&& .NEAR TERM /UNTIL 6 PM THIS EVENING/... A SHORT WAVE TROUGH WILL ARRIVE INTO THE NORTHEAST LATER TODAY, AND AS IT DOES IT SHOULD TEND TO WEAKEN. A WEAK COLD FRONT AT THE SURFACE IS TIED TO THIS FEATURE, AND WITH SOME MOISTURE ON THE INCREASE SOME ADDITIONAL SHOWERS AND A THUNDERSTORM ARE EXPECTED TO DEVELOP TO OUR WEST. THERE IS SOME INSTABILITY DURING THE DAY, WITH THIS PROBABLY BEST ACROSS THE WESTERN ZONES. HOWEVER, THE FORECAST SOUNDINGS MOSTLY SHOW A SKINNY CAPE PROFILE WHICH TENDS TO KEEP UPDRAFTS ON THE WEAKER SIDE. THE BULK OF THE LIFT ASSOCIATED WITH THE TROUGH AXIS IS FORECAST TO BE TO OUR WEST DURING PEAK HEATING WITH THE ACTUAL SHORT WAVE AND THE RIGHT ENTRANCE REGION OF AN UPPER- LEVEL JET. HOWEVER, TERRAIN INFLUENCES ALONG WITH WEAK SURFACE CONVERGENCE COULD BE ENOUGH AND THEREFORE WE KEPT A SLIGHT CHC POP ACROSS THE NORTHWESTERN ZONES. THIS WAS DELAYED A BIT THOUGH GIVEN SLOWER CUMULUS DEVELOPMENT THUS FAR. HIGH LEVEL CLOUDINESS IS STREAMING NORTHWARD FROM MARYLAND AND DELAWARE. IT WILL BE RATHER WARM TO HOT ACROSS MUCH OF THE CWA THIS AFTERNOON, HOWEVER DEW POINTS MAY LOWER A LITTLE BIT BY LATE DAY IN SOME AREAS DUE TO SIGNIFICANT HEATING OF THE BOUNDARY LAYER. THE PRESSURE GRADIENT IS NOT FORECAST TO BE ALL THAT TIGHT, THEREFORE LIGHT ENOUGH FLOW WILL RESULT IN A SEA BREEZE ONCE AGAIN THROUGH THIS AFTERNOON. THE HOURLY GRIDS WERE ADJUSTED BASED ON THE LATEST OBSERVATIONS, THEN THE LAMP/LAV GUIDANCE WAS BLENDED IN TO ASSIST. NO MAJOR CHANGES WERE MADE TO THE HIGH TEMPERATURES ATTM. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 AM MONDAY/... ANY ISOLD SHWRS OR TSTMS WILL COME TO AN END AND THEN EXPECT JUST A PCLDY SKY WITH GRADUALLY INCREASING DEW PTS, AS THE HIGH REMAINS THE DOMINANT WX FEATURE AS WE CLOSE OUT AUGUST AND METEOROLOGICAL SUMMER. && .LONG TERM /MONDAY THROUGH SATURDAY/...
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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.
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&& .AVIATION /18Z SUNDAY THROUGH FRIDAY/...
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THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY AND SURROUNDING AREAS. THIS AFTERNOON...VFR WITH SOME CUMULUS DEVELOPING AROUND 5000 FEET, ALONG WITH HIGH LEVEL CLOUDS MOVING THROUGH. SOUTHWESTERLY WINDS UP TO 10 KNOTS, WHICH SHOULD TURN MORE SOUTHERLY AT KACY AND PERHAPS KILG DUE TO A SEA/BAY BREEZE. AN ISOLATED SHOWER OR THUNDERSTORM MAY APPROACH THE KABE TO KRDG AREAS TOWARD EVENING. 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 RATHER LOW. SOUTHWESTERLY WINDS 5-10 KNOTS, BECOMING LIGHT AND VARIABLE AT MANY OF THE TERMINALS. 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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NO MARINE FLAGS ARE ANTICIPATED THRU THE NR AND SHORT TERM PDS. SEAS WILL GENLY BE IN THE 2 TO 3 FT RANGE. WIND WILL GENLY BE SW IN THE 10 TO 15 KT RANGE WITH GUSTS AS HIGH AS 20 KT. 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 WINDS TURNING MORE SOUTHERLY AND INCREASING SOME THROUGH THE DAY 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...
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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
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&& .PHI WATCHES/WARNINGS/ADVISORIES... PA...NONE. NJ...NONE. DE...NONE. MD...NONE. MARINE...NONE. && $$ SYNOPSIS...GORSE/JOHNSON/DRAG 123P NEAR TERM...GORSE SHORT TERM...NIERENBERG LONG TERM...DRAG 123P AVIATION...DRAG/GORSE/JOHNSON 123P MARINE...DRAG/JOHNSON/NIERENBERG 123P RIP CURRENTS...GORSE/DRAG 123P CLIMATE...DRAG 123P

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