Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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000 FXUS61 KPHI 262046 AFDPHI AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MOUNT HOLLY NJ 446 PM EDT THU MAR 26 2015 .SYNOPSIS... A STRONG COLD FRONT SWEEPS THROUGH THE REGION TONIGHT INTO FRIDAY MORNING. A WEAK LOW PRESSURE SYSTEM MAY FORM ALONG THIS FRONT AS IT RESIDES OFFSHORE ON SATURDAY. STRONG CANADIAN HIGH PRESSURE IS EXPECTED TO MOVE THROUGH THE REGION ON SUNDAY INTO MONDAY BEFORE ANOTHER COLD FRONT PASSAGE LATER ON MONDAY. ANOTHER SHOT OF HIGH PRESSURE FOR TUESDAY AND WEDNESDAY IS EXPECTED AHEAD OF THE NEXT COMPLEX LOW PRESSURE SYSTEM ON THURSDAY. && .NEAR TERM /UNTIL 6 AM FRIDAY MORNING/... SHOWERS WILL CONTINUE TO MOVE THROUGH THE REGION THIS AFTERNOON WITH ISOLATED THUNDER REMAINING POSSIBLE. TEMPERATURES HAVE WARMED BEHIND THE WARM FRONT AND SHOULD RISE A COUPLE OF MORE DEGREES OVER THE NEXT FEW HOURS IN THE CONTINUING WARM ADVECTION BEFORE THE COLD FRONT ARRIVES TONIGHT. THE COLD FRONT WILL CROSS THE REGION TONIGHT BRINGING IN ANOTHER ROUND OF RAIN. INSTABILITY LOOKS LIMITED ALONG THE FRONTAL BOUNDARY BUT THERE IS ENOUGH THAT SOME THUNDERSTORMS MAY DEVELOP AS THE FRONT IS CROSSING THE REGION. THINGS TURN COLDER BEHIND THE COLD FRONT AS WE SEE STRONG COLD AIR ADVECTION TAKING PLACE. TEMPERATURES WILL DROP QUICKLY BEHIND THE FRONT, ABOUT 10 TO 20 DEGREES COLDER. TEMPERATURES WILL FALL INTO THE 30S AND 40S OVERNIGHT, WITH SOME UPPER 20S ACROSS THE SOUTHERN POCONOS. WITH THE COLDER TEMPERATURES, THERE MAY BE A CHANGEOVER TO OR A MIX OF RAIN AND SNOW AS THE FRONT MOVES OFFSHORE AND THE PRECIPITATION STARTS TO DIMINISH. RAINFALL AMOUNTS WILL GENERALLY BE AROUND A HALF OF AN INCH OR LESS WITH LITTLE TO NO SNOW ACCUMULATION, THOUGH WE`LL MONITOR THE FCST FOR THE POCONOS. && .SHORT TERM /6 AM FRIDAY MORNING THROUGH 6 PM FRIDAY/... THE COLD FRONT MAKES ITS WAY OFF THE COAST FRIDAY WITH SOME LINGERING RAIN HANGING AROUND - POSSIBLY MIXED WITH ICE PELLETS OR WET SNOW AT DAYBREAK VCNTY I-95 NWWD. PCPN ENDING FROM NW TO SE DURING THE AFTN AS A WAVE OF LOW PRESSURE FORMS OFFSHORE. TEMPERATURES WILL BE MUCH COOLER ON FRIDAY IN MANY AREAS COMPARED TO TODAYS MAX TEMPS. HIGHS WILL BE IN THE 40S TO NEAR 50 ACROSS THE REGION ON FRIDAY WITH PLENTY OF CLOUD COVER AROUND. NORTHWEST WINDS MAY BE GUSTY EARLY BUT SHOULD RELAX AS THE FRONT MOVES OFFSHORE. && .LONG TERM /FRIDAY NIGHT THROUGH THURSDAY/... 5-WAVE MODEL GUIDANCE SHOWS BROAD TROUGHING IN THE EAST WITH BROAD RIDGING ACROSS THE WESTERN STATES THROUGH MOST OF THE LONGTERM PERIOD. THE PATTERN ALOFT HAS A FAST FLOW LOOK WITHOUT MUCH BLOCKING WHICH ADDS TO A BIT OF THE UNCERTAINTY/TIMING OF EMBEDDED SHORTWAVES WITHIN THE MID-LEVEL FLOW. TOWARDS THE END OF THE PERIOD A NEARLY ZONAL FLOW LOOKS TO TAKE SHAPE. FRIDAY NIGHT - SATURDAY...DEEP ANOMALOUS MID-LEVEL TROUGH WILL BE OVERHEAD AS STRONGER NORTHERN STREAM ENERGY TRIES TO PHASE WITH WEAKER, SLOWER MOVING, SOUTHERN STREAM ENERGY. EVEN WITH MINIMAL PHASING SURFACE CYCLOGENESIS LOOKS TO OCCUR TO THE SOUTH OF OUR REGION LATE ON FRIDAY. THIS WEAK INFLECTION WILL MOVE ALONG THE AFOREMENTIONED COLD FRONT SITTING OFFSHORE ON SATURDAY AND COULD THROW SOME LIGHT PRECIPITATION BACK ACROSS THE REGION DURING THE DAY. THINKING THAT A MAJORITY OF THE LIFT AND MOISTURE WITH THIS SYSTEM WILL REMAIN TO OUR NORTHEAST, OVER NEW ENGLAND, AND FARTHER OFFSHORE. THE PASSAGE OF THE MID-LEVEL LOW COULD ALSO SPARK A FEW INSTABILITY SHOWERS DURING THE AFTERNOON. THERMALLY WE WILL BE DROPPING BELOW FREEZING THROUGHOUT THE COLUMN BY SATURDAY AFTERNOON SO MOST OF THE PRECIPITATION SHOULD FALL AS SNOW. TRYING TO COMBAT ANY DAYTIME HEATING, EVEN WITH A MULTITUDE OF CLOUDS AND NORTHERLY WINDS, WILL BE TOUGH WITH BOUNDARY LAYER TEMPERATURES EXPECTED TO BE IN THE MID TO UPPER-30S...THE ONE CAVEAT WOULD BE STRONGER DYNAMIC COOLING WITH THE PLACEMENT OF AN INVERTED TROUGH/MESOSCALE BANDING FEATURE...THOUGH IT IS ILL-DEFINED ACROSS OUR AREA AT THIS TIME. SUNDAY...RIDGING TO OUR SOUTH RE-ESTABLISHES IT SELF ACROSS THE REGION FOR THE SECOND HALF OF THE WEEKEND. THIS WILL PROVIDE MOSTLY CONDITIONS ACROSS THE REGION AS TEMPERATURES REMAIN WELL BELOW NORMAL. MONDAY...RIDGING SLIDES OFF THE SOUTHEAST COAST AND A RETURN FLOW WITH LOW-LEVEL WARM AIR ADVECTION KICKS IN. TEMPERATURES MAY BE ABLE TO WARM TO ABOVE NORMAL, AS WE CONTINUE THE TUMULTUOUS EARLY SEASON TEMPERATURE SWINGS. THERE DOES NOT APPEAR TO BE A GREAT DEAL IN MOISTURE SURGE WITH THIS NEXT SYSTEM, AS IT APPROACHES FROM THE WEST. WITH THE LACK OF MOISTURE WE KEEP THE SLIGHT CHANCE POPS IN THE FORECAST, THOUGH THE BETTER LIFT WILL ACCOMPANY THE ADVANCING COLD FRONT LATER MONDAY AFTERNOON SO POPS MAY BE INCREASED IN TIME. TUESDAY - THURSDAY...THE FLOW ALOFT, AS MENTIONED ABOVE, REMAINS QUICK AND ACTIVE. NUMEROUS EMBEDDED WAVES OF ENERGY SLIDE THROUGH THE REGION DURING THIS TIMEFRAME, EACH CARRYING THE CHANCE FOR SHOWERY ACTIVITY. THE BETTER CHANCES FOR SHOWERS WILL BE WEDNESDAY INTO THURSDAY AS ANOTHER SYSTEM PUSHES IN FROM THE WEST. ANOTHER LOW- LEVEL MOISTURE SURGE IS EXPECTED WITH THIS SYSTEM AS TEMPERATURES LOOK TO REMAIN AT OR SLIGHTLY ABOVE AVERAGE FOR THE FIRST COUPLE DAYS OF APRIL...THIS COULD EASILY CHANGE WITH TIME. && .AVIATION /21Z THURSDAY THROUGH TUESDAY/... THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY, AND SURROUNDING AREAS. THROUGH TONIGHT...CURRENTLY MVFR-VFR CIGS PREDOMINANT PHL/KILG WHILE IFR CONDS VCNTY SHOWERS KMIV AND KACY AND IFR CONDS PREVAIL ELSEWHERE. THE VARIED SUB VFR CONDS WILL CONTINUE THROUGH THE NIGHT, BASICALLY DEGRADING BACK TO IFR WITH SHOWERS BECOMING WIDESPREAD OVERNIGHT, ESPECIALLY THE CFP THIS EVENING. THE CFP WILL PROBABLY BE ACCOMPANIED BY A BRIEF NW WIND GUST OF 25-30 KTS AND A HEAVY SHOWER AS PER THE HRRR. THE CFP IS BEING ADVANCED FASTER AND EXPECT THROUGH KRDG/KABE 23Z, KPHL/KPNE/KTTN/KILG NEAR 02Z, AND KMIV/KACY BETWEEN 03Z-04Z/27. GUSTY SOUTHERLY WINDS THIS AFTERNOON WILL BECOME BRIEFLY GUSTY NW TO 25-30 KT WITH THE CFP THIS EVENING...THEN SETTLE BACK A BIT DURING THE NIGHT. ICING COULD DEVELOP IN PCPN TOWARD DAWN NEAR AND NW OF THE I-95 CORRIDOR INCLUDING KPHL, ESPECIALLY NEAR 5000 FT AS A SUB FREEZING LAYER IS MODELED TO DRIVES SEWD WHILE PCPN IS ON-GOING. FRIDAY...IFR OR MVFR CONDS AT DAYBREAK IN PCPN WILL IMPROVE TO VFR CIGS ACROSS THE TERMINALS FROM NORTHWEST TO SOUTHEAST DURING THE MORNING EXCEPT NOT REACHING KMIV AND KACY UNTIL SOMETIME DURING THE AFTERNOON. WINDS WILL BE OUT OF THE NORTHWEST WITH SPEEDS AROUND 10 KNOTS, A FEW GUSTS TO 20 KT. OUTLOOK... FRIDAY NIGHT - SATURDAY...MVFR OR LOWER POSSIBLE IN RAIN/SNOW SHOWERS. NORTHERLY WINDS. SUNDAY - MONDAY...VFR. NORTHERLY WINDS VEER TOWARDS THE SOUTHWEST AND BEGIN TO GUST MONDAY AFTERNOON. TUESDAY...VFR. WINDS VEER TOWARDS THE WEST-NORTHWEST...GUSTS EXPECTED. && .MARINE... MWW UPDATED FOR GALE FORCE GUSTS. MWS ISSUED FOR GALE FORCE GUSTS THROUGH ABOUT 8PM TODAY. HAVE HAD A NUMBER OF REPORTS OF GALE FORCE GUSTS ALONG OUR COASTS THIS AFTN. OTHERWISE A SMALL CRAFT ADVISORY REMAINS IN EFFECT ACROSS THE AREA WATERS, ENDING ON THE DELAWARE BAY AT 12Z FRIDAY AND ON THE OCEAN FRONT AT 22Z FRIDAY. SOUTHERLY WINDS ACROSS THE WATERS THIS AFTERNOON WILL START TO VEER TO THE WEST AS A COLD FRONT APPROACHES THE WATERS. THE COLD FRONT WILL REACH THE AREA WATERS IN THE 05-09Z TIME FRAME AND THEN MOVE OFFSHORE, LEAVING US WITH NORTHWEST WINDS. WINDS WILL GUST BEHIND THE FRONTAL PASSAGE BUT SHOULD DIMINISH THROUGH THE DAY. WAVES ARE RUNNING AROUND 4 TO 6 FEET ON THE OCEAN THIS AFTERNOON AND WILL REMAIN ELEVATED THROUGH FRIDAY. WAVES ON THE BAY ARE GENERALLY AROUND 2 TO 4 FEET. OUTLOOK... FRIDAY NIGHT - SATURDAY...SEAS WILL SUBSIDE LATE FRIDAY EVENING BUT COULD INCREASE A TAD SATURDAY WITH A NORTHERLY SURFACE FLOW DEVELOPING. COULD SEE SCA SEAS SATURDAY AFTERNOON. SUNDAY - TUESDAY...POSSIBLE SCA CONDITIONS SUNDAY THROUGH TUESDAY. WINDS VEER TOWARDS THE WEST AND THEN SOUTHWEST BY MONDAY AS HIGH PRESSURE SLIDES OFFSHORE. A COLD FRONT SLIDES THROUGH ON MONDAY EVENING AND WINDS MAY STAY ABOVE SCA THROUGH TUESDAY NIGHT. && .PHI WATCHES/WARNINGS/ADVISORIES... PA...NONE. NJ...NONE. DE...NONE. MD...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 6 PM EDT FRIDAY FOR ANZ450>455. SMALL CRAFT ADVISORY UNTIL 8 AM EDT FRIDAY FOR ANZ430-431. && $$ SYNOPSIS...HEAVENER NEAR TERM...MEOLA 446 SHORT TERM...MEOLA 446 LONG TERM...HEAVENER AVIATION...HEAVENER/MEOLA 446 MARINE...DRAG/HEAVENER/MEOLA 446

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