Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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000 FXUS61 KPHI 261028 AFDPHI AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MOUNT HOLLY NJ 628 AM EDT SUN JUL 26 2015 .SYNOPSIS... A COLD FRONT WILL APPROACH FROM THE NORTHWEST TODAY AND CROSS THE AREA TONIGHT AND EARLY MONDAY. THE FRONT WILL REMAIN TO THE SOUTH OF THE AREA THROUGH EARLY TUESDAY BEFORE DISSIPATING. HIGH PRESSURE WILL MOVE IN TUESDAY AND REMAIN INTO WEDNESDAY. ANOTHER FRONT WILL AFFECT THE REGION NEXT THURSDAY AND THURSDAY NIGHT. MORE HIGH PRESSURE WILL MOVE IN FOR FRIDAY AND INTO THE WEEKEND. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... WITH THE NEXT ESTF UPDATE WE ADDED SOME ISOLATED SHOWERS FAR NORTHERN NEW JERSEY. PCPN`S TRAJECTORY SHOULD KEEP THE THUNDER AND MORE WIDESPREAD PCPN FARTHER TO THE NORTHEAST. THE SHORT WAVE AND WAA TRIGGERING THIS AREA WILL MOVE INTO NEW ENGLAND THIS MORNING. THE 06Z MODEL RUNS HAVE NOT ADDED ANY FURTHER CLARITY TO CONVECTIVE CHANCES AS THE WRF AND GFS ARE PRETTY FAR APART. THE ONLY CONTINUITY THEY MAINTAIN IS THAT PCPN CHANCES SHOULD NOT END WITH SUNSET. WHILE THE GFS CONTINUES TO INITIALIZE BETTER THAN THE WRF-NMMB WITH THE BIG PICTURE AT 500MB, THE WRF-NMMB INITIALIZED BETTER THAN THE GFS AT 850MB AND 925MB AND IT HAD A VERY GOOD VERIFICATION OF PREDICTED QPF ACROSS THE NERN CONUS THROUGH 06Z, BESTING BOTH CANADIANS AND THE ECMWF. THE DP/DT CONTINUES TO SHOW A STRONGER HEAT RIDGE WITH ITS OVERALL NEWD DEFLECTION OF OTHER FEATURES. OVERALL NO CHANGE IN OUR ROAD TOWARD MORE HUMID WEATHER TODAY WITH SIMILAR MAX TEMPS AS WELL AS THE CHANCE FOR AFTN THUNDERSTORMS. ALSO THE GENERAL IDEA OF A HIGH DCAPE AND LOW SHEAR ENVIRONMENT (WHERE THE THUNDER OCCURS TODAY) CONTINUES. LOOKING AT THE MESOSCALE MODELS FOR THIS MORNING, WITH THE STGST MID LEVEL WAA THROUGH, NO UPSTREAM CONVECTION AND CONVECTIVE TEMPS OUT OF REACH, WE WILL START THE FORECAST DRY AT SUNRISE (SHOWERS EARLY FAR NORTH) UNTIL THE CONVECTIVE TEMP IS REALIZED LATE THIS MORNING/EARLY THIS AFTERNOON NORTH. PVA COMES IN LATER THIS AFTERNOON WITH BEST MIXED LAYER CAPES NORTH AND WEST OF THE INTERSTATE 95 CORRIDOR. USED NCAR MIXED LATER CAPES AOA 1000J AS INITIATION FOR THUNDER. AS THE AFTERNOON PROGRESSES, GIVEN THAT THE BEST CAPE ONLY SLOWLY EASES SOUTH AND EAST (ALSO HOW THE CONVECTING MODELS BEGRUDGINGLY BRING CONVECTION SE OF THE POCONOS), WE WERE CONSERVATIVE WITH POPS GETTING TO THE I95 CORRIDOR. SOME MESOSCALE MODELS DONT BRING CONVECTIVE CHANCES TO PHL UNTIL AFTER 04Z. AS FAR AS STRONG/SEVERE GOES, BEST CHANCE MAY BE IN THE POCONOS BECAUSE OF THEIR PROXIMITY TO AN EVER WEAKENING LLJ AND PRESENCE OF DECENT DCAPE COINCIDING WITH MAX HEATING. BUT BULK SHEAR VALUES ARE LOWEST NORTH AND THUS ANY STORMS OF SIGNIFICANT STRENGTH SHOULD BE ISOLATED AND PULSY. 10C PLUS 925 TEMPS CAME CLOSEST TO FITTING YESTERDAY`S MAX TEMPS. THESE ARE BASICALLY GIVING OUR CWA A STATUS QUO FOR HIGH TEMPS TODAY. DEW POINTS THOUGH WILL BE 10 TO 15 DEGREES HIGHER, SO IT WILL NOT FEEL AS GOOD EVEN WITH MORE OF A BREEZE THAN YESTERDAY. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 AM MONDAY/... WORKED THROUGH A SIMILAR SCENARIO LAST WEEKEND IN WHICH THE MODELS WERE DEPICTING CONVECTION GOING THROUGH THE NIGHT. THE COLD POCKET AT 500MB OVER WISCONSIN OFF THE 00Z SOUNDINGS WILL BE MOVING OVER OUR CWA OVERNIGHT. THIS PARTIALLY COMPENSATES FOR A SLIGHT DOWNTICK IN 850MB AND 925MB TEMPS. 850MB MOISTURE IS PREDICTED TO INCREASE AND THIS APPEARS TO BE THE ULTIMATE DRIVER TO CONVECTIVE SUSTAINABILITY ALONG WITH A DECENT SHORT WAVE OVERNIGHT. WE START CINING IN THE EVENING, SO ONGOING CONVECTION OR LIFT ABOVE THE 925MB FRONT WILL BE NEEDED TO KEEP ON GOING. THE SURFACE COLD FRONT OVER THE EASTERN GREAT LAKES CURRENTLY WILL BE VERY DIFFICULT TO FIND OR MAYBE EVEN EXIST BY TONIGHT. MODELS ARE ALSO DISPLACED AS TO WHETHER BEST CHANCES WILL BE NORTH VS SOUTH AND ADD TO THAT THE SPC WRF HAS A SAGGING DUE SOUTH COMPLEX DROPPING NEARLY ENTIRELY WEST OF OUR CWA. WE KEPT POPS IN THE CHANCE CATEGORY. BECAUSE OF EXPECTED CLOUDINESS AND HIGHER DEW POINTS, WE WENT AT OR ABOVE STAT GUIDANCE FOR MINS. && .LONG TERM /MONDAY THROUGH SATURDAY/... THE FORMER COLD FRONT...NOW A TROUGH...WILL FURTHER WEAKEN AS IT CROSSES THE AREA MONDAY AND MONDAY NIGHT. THE GATHERING HEAT AND HUMIDITY WILL HELP BRING CHCS FOR SHOWERS AND TSTMS WITH THE FRONT. LOCAL DOWNPOURS EXPECTED. THE EXTRA CLOUDINESS ACROSS THE AREA WILL HOLD TEMPS DOWN A BIT...BUT THEY WILL STILL BE ABOVE NORMAL WITH MID/UPPER 80S EXPECTED IN MOST AREAS. WE WILL KEEP A DRY FCST FOR TUE THROUGH WED NIGHT FOR NOW. HIGH PRESSURE WILL SETTLE ACROSS THE AREA AS AN UPPER HIGH BUILDS TOO. THIS WILL BRING DRY WEATHER WITH HOT TEMPERATURES AS WELL. HIGHS BOTH DAYS WILL BE IN THE 90S IN MANY AREAS...WITH THE WARMER DAY BEING WED WHERE SOME MID 90S MAY OCCUR ACROSS THE URBAN AREAS. DEW POINTS WILL BE HIGH TOO...SO A COUPLE OF HEAT RELATED HEADLINES ARE POSSIBLE. A COLD FRONT WILL BRING AN END TO THE HEAT AND HUMIDITY LATER THU. THERE WILL STILL BE SOME TEMPS IN THE 90S BEFORE THE FRONT ARRIVES...SO MANY AREAS WILL QUALIFY FOR A HEAT WAVE BEFORE THE WEEK IS OUT. SCT TSTMS ARE EXPECTED WITH THE FRONT SO CHC POPS ARE IN THE GRIDS FOR NOW. THE FRONT WILL MOVE OFFSHORE THU NIGHT. FRI AND THE EARLY PART OF THE WEEKEND WILL HAVE MOSTLY DRY WEATHER FOR THE AREA. A COUPLE SCT TSTMS COULD OCCUR ACROSS THE DELMARVA REGION WHERE THE AFOREMENTIONED FRONT AND A FEW WEAK WAVES WILL INTERACT. SLGT CHC POPS ARE IN THE THESE AREAS FOR NOW. TEMPS WILL STILL BE ABOVE NORMAL...BUT MOSTLY SUB-90 DEGREES AND MOSTLY COMFORTABLE DEW POINTS...EXCEPT ACROSS THE DELMARVA AND SRN NJ. && .AVIATION /10Z SUNDAY THROUGH THURSDAY/... THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY AND SURROUNDING AREAS. PLANNED 12Z TAFS WILL REMAIN VFR INTO EARLY AFTERNOON, THEN SOME UNCERTAINTY AS TO EXTENT OF SHOWERS AND THUNDERSTORMS DURING THE LATE AFTERNOON AND EVENING. THIS MORNING...VFR. SOME MID LEVEL CLOUDINESS NORTHERN AIRPORTS, OTHERWISE JUST SOME CUMULUS CLOUDS DEVELOPING ALONG WITH CIRRUS ABOVE IT. LIGHT SOUTH TO SOUTHWEST WINDS DEVELOPING. MORE CONFIDENT ABOUT FOG NOT HAVING ANY IMPACT AS TEMPERATURE AND DEW POINT SPREAD REMAINS PRETTY FAR APART. THIS AFTERNOON...VFR WITH STRONGER SOUTH TO SOUTHWEST WINDS AVERAGING CLOSER TO 10 KNOTS. IF THERE IS A SEA BREEZE FRONT, ITS TOUGH TO DECIPHER IT AS THE GENERAL FLOW WILL BE EITHER SOUTH OR SOUTHWEST. SCATTERED SHOWERS AND THUNDERSTORMS SHOULD START FORMING IN THE NORTHWEST PART OF OUR AREA. WE ADDED A TEMPO GROUP FOR THUNDERSTORMS AT KABE AND KRDG LATE. THIS EVENING...VFR CIG EXPECTED. SOUTH WINDS WILL BECOME LIGHTER. SHOWERS AND THUNDERSTORMS SHOULD SPREAD FARTHER TO THE SOUTHEAST. BECAUSE INSTABILITY WILL BE DECREASING, TERMINALS EITHER HAVE SHOWERS OR VCSH. WE KEPT KACY AND KMIV PCPN FREE AS ANY PRECIPITATION THAT WOULD MAKE IT THERE SHOULD BE AFTER 06Z. OVERNIGHT...A VFR CIG AT MOST TERMINALS. SOME MVFR FOG PREDICTED AT MORE RURAL TERMINALS AND AIRPORTS. LIGHT WINDS. NOT CONFIDENT ENOUGH ABOUT EXTENT/IMPACT OF SHOWERS AND ISOLATED THUNDERSTORMS TO INCLUDE AT ANY TAF SITES. OUTLOOK... MON/MON NIGHT...VFR EXCEPT IN SCT TSTMS WHERE LOWER CIGS/VSBYS POSSIBLE. TUE THRU WED NIGHT...MOSTLY VFR. AREAS OF HAZE POSSIBLE DURING THE DAYTIME HOURS AND PATCHY FOG POSSIBLE AT NIGHT. THURS...SCT TSTMS WITH LOWER CIGS/VSBYS POSSIBLE. && .MARINE... WE ARE EXPECTING SUB SMALL CRAFT ADVISORY CONDITIONS TODAY AND TONIGHT. WINDS WILL BE INCREASING IN THE SOUTH TO SOUTHWEST FLOW PRECEDING THE WEAKENING COLD FRONT TODAY. THE TREND ON THE LLJ, IF ONE WANTS TO CALL IT THAT, IS WEAKER. REGARDLESS WE SHOULD HAVE SOME AROUND 20 KNOT GUSTS THIS AFTERNOON, ESPECIALLY NEAR THE IMMEDIATE COAST AND INLETS AND ALSO DEVELOPING IN DELAWARE BAY. GIVEN THAT THE BEST CONVECTION IS NOT EXPECTED TO REACH THE AREA WATERS UNTIL TONIGHT, DECREASES THE RISK OF STORMS REACHING SPECIAL MARINE WARNING CRITERIA. WINDS SHOULD ALSO DIMINISH TONIGHT. OUTLOOK... SUB-SCA CONDITIONS EXPECTED MUCH OF THE TIME...EXCEPT FOR THU/THU NIGHT WHEN SOME LOW END SCA GUSTS/SEAS POSSIBLE. SCT TSTMS MON/MON NIGHT AND THU/THU NIGHT WILL CREATE LOCALLY HIGHER WINDS AND SEAS. && .RIP CURRENTS... WITH THE LONG PERIOD (11-12 SECOND) 1 TO 2 FOOT EASTERLY SWELL CONTINUING...EXPECT THE MODERATE RISK OF DANGEROUS RIP CURRENTS TO ALSO CONTINUE TODAY. && .PHI WATCHES/WARNINGS/ADVISORIES... PA...NONE. NJ...NONE. DE...NONE. MD...NONE. MARINE...NONE. && $$ SYNOPSIS...O`HARA NEAR TERM...GIGI SHORT TERM...GIGI LONG TERM...O`HARA AVIATION...O`HARA MARINE...GIGI/O`HARA RIP CURRENTS...

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