Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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000 FXUS61 KPHI 230700 AFDPHI AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MOUNT HOLLY NJ 300 AM EDT WED JUL 23 2014 .SYNOPSIS... HIGH PRESSURE WILL CONTINUE TO MOVE EASTWARD ALLOWING FOR A BETTER RETURN FLOW TODAY AHEAD OF A POTENT COLD FRONT. THE FRONT SHOULD MOVE THROUGH OUR AREA LATE TONIGHT INTO THURSDAY MORNING. HIGH PRESSURE WILL FILL IN BEHIND THE DEPARTING FRONT THROUGH THE FIRST HALF OF THE WEEKEND BEFORE A COMPLEX SYSTEM APPROACHES SUNDAY SPILLING INTO THE NEW WORK WEEK. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... FAIR EARLY THIS MORNING...PATCHY FOG TOWARD 10Z...MAINLY NW NJ. PATCHY CLOUDINESS FORMING...AOA 5000 FT AS A SEPARATE KI AXIS DEVELOPS OVER NJ/EPA TOWARD 12Z. TODAY...LITTLE CHANGE FROM PRIOR FORECASTS. MODEL GUIDANCE STATES WIDESPREAD LOWER 90S (NEAR 18C 850 MB AND 925MB HOTTEST TEMPS ARE JUST WEST AND NORTHWEST OF OUR FCST AREA). POCONOS AND IMMEDIATE ATLC SHORE A BIT COOLER. ECMWF SEEMS TO HOLD BACK SLIGHTLY. THE FCST TEMPS ISSUED AT 330 AM MAY BE A DEGREE TOO WARM. HEAT INDEX UPPER 90S....CLOSE TO 100 BUT NO HEAT ADVY ISSUED ATTM. TSTMS PROBABLY RESTRICTED TO NW NJ AND E CENTRAL AND NE PA AFTER 21Z...POSSIBLY A SECOND CLUSTER CROSSING CHES BAY? TT 48+ SWI -2 KI INCREASING TO 38C VCNTY POCS AND E VA. APPEARS TO BE A SEE TEXT CASE...UNLIKELY SVR THROUGH 00Z DUE TO LACK OF BULK SHEAR...500MB WINDS UNDER 30 KT AND MLCAPE CLOSER TO 1600J. NOTE THAT THERE SHOULD BE CU FIELDS FORMING THIS MORNING OVER NNJ IN A LEADING EDGE AREA OF KI 33C BUT WITH LITTLE OR NO PRIMARY FORCING...AM NOT EXPECTING TO YIELD ANY LATE MORNING TSTMS IN NNJ AS THIS LEADING PATCH OF INSTABILITY SHOVES ENE TO LI BY 18Z. TODAYS FCST BASIS: NAM TEMPS (50 50 BLEND OF 00Z/23 NAM METMOS AND THE NAM 2M TEMPS). OTHERWISE...OTHER ELEMENTS A 50 50 BLEND OF THE 00Z/23 NAM/GFS GUIDANCE IN THIS 330 AM ISSUANCE. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 AM THURSDAY/... SLOW SEWD PROGRESS OF THE COLD FRONT INTO THE UNSTABLE AIRMASS SHOULD YIELD BANDS OF TSTMS INTO THE NIGHT BUT NOT NECESSARILY WIDESPREAD. ONE OR 2 TSTMS COULD BE SVR BUT BULK SHEAR FOR SVR IS MARGINAL AT WORST AND ONLY THE TT AND SOME CAPE ALLOW FOR MODEST ISOLATED SVR POTENTIAL. PWAT 1.8 INCHES OFFERS A CHANCE OF NARROW PATHS OF 2 INCH RAINS BENEATH THE BIGGEST STORMS. LIGHTNING STRIKES MIGHT BE THE BIG PROBLEM? FCST BASIS; 50 50 BLEND OF THE 00Z/23 GFS/NAM GUIDANCE IN THIS 330 AM ISSUANCE EXCEPT MOSTLY NAM METMOS TEMPS. && .LONG TERM /THURSDAY THROUGH TUESDAY/... THE BASE OF THE TROUGH BEGINS TO FLATTEN OUT BY FRIDAY, THOUGH NOT ENTIRELY BECOMING ZONAL. THIS YIELDS SLIGHTLY BELOW NORMAL TEMPERATURES AND DECREASED CHANCES FOR CONVECTION GIVEN A DRIER AIRMASS IN PLACE. STILL A BIT UNCERTAIN ABOUT THE SATURDAY EVENING TIMEFRAME AS SOME OF THE OPERATIONAL GUIDANCE SWINGS A PIECE ENERGY THROUGH THE BASE OF THE TROUGH WHICH COULD TOUCH OFF A COUPLE STRAY/ISOLATED SHOWERS...BETTER EAST THAN WEST WITH BETTER MOISTURE POOLING AND SEABREEZE INTERACTION. RIDGING BUILDS INTO THE WEST SENDING STRONGER SHORTWAVES OF ENERGY INTO THE TROUGH OVERHEAD ALLOWING FOR ANOTHER BOUT OF DEEPER TROUGHING. EXPECT UNSETTLED WEATHER THROUGH THE REMAINDER OF THE LONGTERM AS A SERIES OF EMBEDDED WAVES PUSHES THROUGH ALOFT TOUCHING OFF SHOWERS AND THUNDERSTORMS. && .AVIATION /07Z WEDNESDAY THROUGH SUNDAY/... THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY AND SURROUNDING AREAS. EARLY THIS MORNING BEFORE 12Z...PRIMARILY VFR WITH SCT CLOUDS AOA 4000 FT. PATCHY 2 TO 5 MI FOG POSSIBLE IN THE COUNTRYSIDE TAF LOCATIONS BUT CONFIDENCE IS LESS THAN IT WAS AT THIS TIME YDY. TEMP-DEWPOINT SPREADS AT 3 AM ARE JUST TOO LARGE FOR FOG. LIGHT S-SW WIND. TODAY AFTER 12Z...VFR SCT AOA 5000 FT. BRIEFLY BKN CIGS NEAR 5000 FT VCNTY KABE AND KRDG THIS AFTN AND CHC OF A TSTM THERE AFTER 22Z WITH GUSTY WEST WIND 30-40 KT. OTHERWISE NON TSTM GRADIENT WINDS SUGGEST SW WIND GUST 17 KT THIS AFTN MOST TAF LOCATIONS. TONIGHT...VFR CIGS WITH A BETTER CHC OF BRIEF IFR CONDS IN TSTMS. LIGHT SW WIND SHIFT N TOWARD MORNING WHEN PATCHY IFR ST/FOG MIGHT FORM IN THE FRONTAL ZONE OR WHERE IT RAINS THIS EVENING. STRONG GUSTY WEST WIND IN A TSTM POSSIBLE BETWEEN 00Z AND 04Z FOR KTTN KPNE KPHL AND KILG BUT LESS CONFIDENCE THAN FOR KABE AND KRDG OUTLINED IN THE PREVIOUS PARAGRAPH. OUTLOOK... THURSDAY...MVFR AND IFR CONDITIONS AT TIMES IN SHOWERS AND THUNDERSTORMS. PATCHY FOG THU MORNING. THURSDAY NIGHT THROUGH SATURDAY...MAINLY VFR. SUNDAY...SUB-VFR POSSIBLE IN SCATTERED SHOWERS AND THUNDERSTORMS. && .MARINE... NO HEADLINES THROUGH TONIGHT. MAINLY S-SW WIND G UNDER 20 KT SHIFT TO NORTH TOWARD DAWN THURSDAY. WAVE HEIGHTS ON OUR OCEAN WATERS SHOULD BE 2 TO 4 FEET. WAVES ON DELAWARE BAY ARE EXPECTED TO BE 2 FEET OR LESS. SCATTERED THUNDERSTORMS TONIGHT. OUTLOOK... THURSDAY THROUGH SUNDAY...HIGH PRESSURE OVERHEAD WILL KEEP SEAS AND WINDS BELOW SCA CRITERIA. && .PHI WATCHES/WARNINGS/ADVISORIES... PA...NONE. NJ...NONE. DE...NONE. MD...NONE. MARINE...NONE. && $$ SYNOPSIS...HEAVENER NEAR TERM...DRAG 3A SHORT TERM...DRAG 3A LONG TERM...HEAVENER AVIATION...DRAG/HEAVENER 3A MARINE...DRAG/HEAVENER 3A

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