Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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000 FXUS61 KPHI 290515 AFDPHI AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MOUNT HOLLY NJ 115 AM EDT WED JUL 29 2015 .SYNOPSIS... HIGH PRESSURE WILL SLIDE OFF THE COAST ON WEDNESDAY GIVING WAY TO A WEAK COLD FRONT PASSAGE ON THURSDAY INTO FRIDAY MORNING. ANOTHER WEAK FRONT MAY CROSS THE REGION SUNDAY INTO MONDAY FOLLOWED BY A BRIEF SHOT OF HIGH PRESSURE. AFTER THE RESPITE OF HIGH PRESSURE A STRONGER COLD FRONT IS EXPECTED TO PASS THROUGH ON TUESDAY. && .NEAR TERM /THROUGH TODAY/...
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THE WEAK BOUNDARY HAS TEMPORARILY WASHED OUT AS LESS DEFINED AND NORTHWARD TO NEAR I-78 EARLY THIS MORNING. A LITTLE FOG WILL FORM DURING THE PREDAWN HOURS BUT NOT AS EXTENSIVE AS SEEN IN YDYS 9Z- 10Z OBS. THE AREAS WHERE IT RAINED LATE YDY MAY BE MORE PREDISPOSED TO FOG FORMATION. AFTER SUNRISE...THE BOUNDARY DRYING BECOMES EVIDENT BY FORENOON WITH HIGHEST DEWPOINTS AND MLCAPE THIS AFTN (400J) CONFINED TO THE SOUTHERN PORTION OF OUR DELMARVA FCST AREA WHERE AM CARRYING A SLIGHT CHC FOR A THUNDERSTORM WITH HEAVY RAIN. PWAT INCREASES TO 1.7 INCHES THERE LATE TODAY. ELSEWHERE...HOT HOT HOT AND USED THE GFS MAVMOS STRAIGHT UP. SEA BREEZES WILL EVENTUALLY MITIGATE SOME OF THE PURE HEAT IN DE AND NJ BUT THIS WILL BE A TOASTY DAY WITH 18C AT 850 AND NEAR RECORD IN SOME PLACES. PLS SEE THE CLIMATE SECTION FOR THE VULNERABLE RECORDS. MAX HI TODAY 98-99F...BASICALLY JUST BELOW URBAN CORRIDOR CRITERIA OF 100. SW WINDS THIS AFTN MAY GUST 15 MPH IN A FEW SPOTS WITH SEABREEZES DEVELOPING ALONG THE COASTS BETWEEN NOON AND 2 PM. CONFIDENCE: ABOVE AVERAGE.
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&& .SHORT TERM /TONIGHT/...
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ANY SHOWERS ON THE DELMARVA SHOULD DISSIPATE BY 00Z. THEREAFTER...SLY FLOW AND MORE HUMID WITH PATCHY FOG AND STRATUS FORMING. PWAT INCREASES TO 1.9 INCHES BY MORNING ALONG THE I-95 CORRIDOR. MODELS HAVE A WEAK IB THRUST ACROSS DE AND S NJ OVERNIGHT WHERE SCT OR ISOLATED HEAVY SHOWERS AND TSTMS MIGHT DEVELOP. TEMPS WELL ABOVE NORMAL AND USED A BLEND OF 00Z/29 NAM/GFS MOS WITH A FAVORING OF THE WARMER AVBL GUIDANCE. CONFIDENCE: ABOVE AVERAGE EXCEPT BELOW AVG ON CONVECTION FORMING OVERNIGHT.
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&& .LONG TERM /THURSDAY THROUGH TUESDAY/...
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5-WAVE MODEL GUIDANCE SHOWS SOUTHEAST RIDGING GIVING WAY TO A DEVELOPING TROUGH ACROSS THE NORTHEASTERN HALF OF THE CONUS BY THE WEEKEND. A FEW IMPULSES WILL TRAVERSE THROUGH THE BASE OF THE TROUGH NEXT WEEK PROVIDING CHANCES FOR MORE UNSETTLED WEATHER EARLY NEXT WEEK. THURSDAY...INCREASING MOISTURE FLUX AHEAD OF THE WEAKENING COLD FRONT MAY BRING IN MORE CLOUD COVER THAN PREVIOUSLY EXPECTED. THERE COULD BE ENOUGH INSTABILITY ADVECTING IN ALOFT TO SPARK SCATTERED SHOWERS WITH EMBEDDED THUNDER DURING THE MORNING HOURS, MOSTLY ACROSS THE SOUTH AND WEST, TO KEEP TEMPERATURES FROM REALLY PEAKING AS HIGH AS PREVIOUSLY THOUGHT, THOUGH LOW-90S IS NOTHING TO SNEEZE AT. THERE WILL BE SOME ENHANCED VERTICAL MIXING DURING THE AFTERNOON WHICH SHOULD KEEP DEWPOINTS FROM STAYING IN THE LOW-70S, SO EXPECTING THEM TO MIX OUT INTO THE UPPER-60S...SHOULD KEEP HEAT INDEX VALUES JUST BELOW ADVISORY CRITERIA BUT STILL HAVE SOME TIME FOR FURTHER ASSESSMENT. BESIDES THE HEAT, THE APPROACH OF THE COLD FRONT LATER IN THE AFTERNOON, WILL TRIGGER MORE SCATTERED SHOWERS AND THUNDERSTORMS. INSTABILITY IS PREVALENT BUT SHEAR IS ON THE WEAKER SIDE AS OF NOW BUT DEPENDING ON THE SHEAR AXIS ORIENTATION TO THE STORMS, WE COULD SEE CELL MERGER OCCUR FORMING A BROKEN LINE OF STORMS WITH STRONGER WINDS THE MAIN ISSUE. PWATS APPROACH AND COULD SURPASS 2" SO HEAVY EFFICIENT RAINERS IS ALSO LIKELY WITH POOR DRAINAGE AND SPOTTY FLASH FLOOD ISSUES POSSIBLE. FRIDAY - SUNDAY...AS MID-LEVEL TROUGHING BEGINS TO STRENGTHEN BY THE WEEKEND, THE AFOREMENTIONED FRONT BECOMES MORE PARALLEL TO THE UPPER- LEVEL FLOW...IT LOOKS TO STALL OFFSHORE. IT BEGINS TO SLOW ITS DEPARTURE EARLY ON FRIDAY SO THERE COULD BE SOME LINGERING SHOWERS AND THUNDERSTORMS FRIDAY MORNING BEFORE DRYING OUT. TEMPERATURES WILL STILL BE QUITE WARM BUT THE FRONT SHOULD BE ABLE TO EAT UP THE HIGHER DEWPOINTS AS THE AIRMASS DRIES OUT A BIT. WE LOOK TO BE ON THE SOUTHERN EXTENT OF THE TROUGHING SO MOST OF THE MID-LEVEL ENERGY STAYS TO OUR NORTH THROUGH THE WEEKEND KEEPING US MOSTLY DRY...COULD BE SOME ISOLATED SHOWERS ACROSS SOUTHERN DELMARVA CLOSER TO THE STALLED BOUNDARY. TEMPERATURES ON SATURDAY AND SUNDAY WILL STILL REMAIN 90+ DEGREES. MONDAY - TUESDAY...ANOTHER COLD FRONT IS PROGGED TO PUSH CLOSER TO THE REGION BY LATE MONDAY INTO TUESDAY. TEMPERATURES AHEAD OF THE FRONT WILL ONCE AGAIN BE 90+ DEGREES WITH A MOISTENING AIRMASS. MORE SCATTERED SHOWERS AND THUNDERSTORMS ARE POSSIBLE.
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&& .AVIATION /04Z WEDNESDAY THROUGH SUNDAY/...
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THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY AND SURROUNDING AREAS. THROUGH 12Z...VFR WITH POSSIBLE MVFR FOG IN THE 6Z-12Z TIME FRAME. LIGHT MOSTLY SW WIND. AFTER 12Z...VFR WITH CLOUDS AOA 6000 FT THIS AFTN. ISOLATED TSTMS POSSIBLE VCNTY KGED AND KESN MID OR LATE THIS AFTN. SW WIND GUST NEAR 15 KT THIS AFTN EXCEPT SOUTH SOUTHEAST SEABREEZES DEVELOPING COASTAL LOCATIONS 16Z-18Z. TONIGHT....VFR TO START THEN PATCHY MVFR OR IFR CONDS IN FOG/STRATUS/ HAZE LATE, ESPECIALLY NW NJ AND PTNS E PA. OUTLOOK... THURSDAY...EARLY MORNING FOG/HAZE WITH MVFR CONDITIONS POSSIBLE...THEN SCT AFTERNOON/EVENING TSTMS WITH MVFR OR LOWER CONDS. FRIDAY - SUNDAY...VFR.
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&& .MARINE...
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NO HEADLINES THROUGH TONIGHT. A DISTANT OCEAN LOW PRESSURE SYSTEM SOUTHEAST OF NEW ENGLAND IS PRODUCING A LITTLE MORE SWELL THAN ANTICIPATED. STILL ATLC SEAS AOB 4 FT THROUGH TONIGHT. SW WINDS LESS 18KT EARLY THIS MORNING BECOMING SSE THIS AFTN AND SLY TONIGHT... ALL GUST SPEEDS AOB 22 KT. OUTLOOK... THURSDAY - SUNDAY...SUB-SCA CONDITIONS EXPECTED THIS PERIOD. THUNDERSTORM CHANCES INCREASE ON THURSDAY WITH VERY HEAVY RAINFALL AND STRONG WIND GUSTS POSSIBLE.
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&& .RIP CURRENTS...
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THERE IS A MODERATE RISK FOR THE DEVELOPMENT OF DANGEROUS RIP CURRENTS ALONG THE NEW JERSEY AND DELAWARE COAST TODAY DUE TO A LONG PERIOD SOUTHEASTERLY SWELL. THE WAVE PERIOD WILL CONTINUE TO BE AROUND 10 SECONDS.
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&& .CLIMATE...
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KACY RAINFALL 6.58 RANKED 14TH WETTEST NOW WITH THE POR DATING BACK THROUGH 1874. WETTEST 13.09 IN 1959. KABE WILL PROBABLY EXPERIENCE NEAR RECORD WARMTH THIS AFTERNOON-JULY 29. THE RECORD THERE IS 96 SET IN 1954. RIGHT NOW WE`RE FCSTG 95. KRDG AND KMPO MAY BE THE OTHER LOCATIONS WITHIN 2F OF THE RECORD FOR THIS DATE KRDG - 97 SET BACK IN 2002. KMPO - 90 SET BACK IN 1949.
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&& .PHI WATCHES/WARNINGS/ADVISORIES... PA...NONE. NJ...NONE. DE...NONE. MD...NONE. MARINE...NONE. && $$ SYNOPSIS...HEAVENER NEAR TERM...DRAG/KLEIN 115A SHORT TERM...DRAG/IOVINO 115A LONG TERM...HEAVENER AVIATION...DRAG/IOVINO/HEAVENER/KLEIN 115A MARINE...DRAG/IOVINO/HEAVENER 115A RIP CURRENTS...115A CLIMATE...115A

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