Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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000 FXUS61 KPHI 192016 AFDPHI AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MOUNT HOLLY NJ 416 PM EDT SAT JUL 19 2014 .SYNOPSIS... HIGH PRESSURE CENTERED OFF NOVA SCOTIA THIS AFTERNOON WILL CONTINUE TO DRIFT NORTHEASTWARD AND IT SHOULD LOSE ITS INFLUENCE OVER OUR REGION. MEANWHILE, WEAK LOW PRESSURE LOCATED OFF THE NORTH CAROLINA COAST WILL MOVE TO THE NORTHEAST AND OUT TO SEA ON SUNDAY. ANOTHER AREA OF HIGH PRESSURE IS EXPECTED TO ESTABLISH ITSELF OVER OUR REGION FOR THE PERIOD FROM MONDAY THROUGH WEDNESDAY. A COLD FRONT FROM THE NORTHWEST IS ANTICIPATED TO ARRIVE ON THURSDAY WITH HIGH PRESSURE FOLLOWING FOR FRIDAY AND SATURDAY. && .NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
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A FRONTAL BOUNDARY LOCATED OFFSHORE AND A SECONDARY SYSTEM OVER THE EASTERN OHIO VALLEY HAVE COMBINED TO PRODUCE A FAIRLY CLOUDY DAY ACROSS THE REGION. A DRY LAYER FROM 700-800 MB HAS PREVENTED A LOT OF THE RADAR ECHOS FROM REACHING THE GROUND. HOWEVER SOME SCATTERED SPRINKLES AND LIGHT SHOWERS ARE BEING OBSERVED ALONG THE NJ AND DE COASTLINES. WILL INDICATE A LOW CHANCE OF PRECIPITATION FOR THOSE REGIONS THROUGH TONIGHT AS THE HRRR CONTINUES TO HINT SOME LIGHT SHOWERS IN THOSE REGIONS. FOR TEMPERATURES AND DEWPOINTS ACCOUNTED FOR LATEST METAR OBSERVATIONS ACROSS THE REGION AS CLOUD COVER HAS KEPT TEMPERATURES IN CHECK TODAY. EASTERLY FLOW SHOULD CONTINUE AS WELL. THE HRRR ALSO HINTS AT ANOTHER AREA OF LIGHT SHOWERS MOVING INTO EASTERN PA AFTER 03Z, SO WENT SLIGHT CHANCE STARTING AT 00Z FOR THE REMAINDER OF THE REGION AWAY FROM THE COAST GIVEN THE REMAINDER OF THE OPERATIONAL MODELS ARE DRIER.
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&& .SHORT TERM /6 AM SUNDAY MORNING THROUGH 6 PM SUNDAY/...
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THERE WAS GOOD AGREEMENT FOR MOST WEATHER ELEMENTS IN THIS FORECAST PERIOD. USING THE 925 MB TEMPERATURES AS REFERENCE WOULD YIELD A HIGH OF 83 AT PHL TOMORROW WHILE THE MODELED TWO METER TEMPERATURES WERE AROUND 80. COMPONENTS OF THE MAV AND MET WERE USED TO GET IN THIS RANGE. THE OVERALL FLOW WILL CONTINUE TO BE FROM THE EAST TO SOUTHEAST AS WELL. IN TERMS OF POPS AND CLOUD COVER, SOME WEAK SHORTWAVES MAY PASS THROUGH THE REGION BUT APPEAR TO HAVE LIMITED MOISTURE ASSOCIATED WITH THEM. AS A RESULT, MOSTLY CLOUDY SKIES ARE STILL EXPECTED BUT HAVE KEPT THE FORECAST DRY.
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&& .LONG TERM /SUNDAY NIGHT THROUGH SATURDAY/... A MID LEVEL TROUGH IS FORECAST TO BE LOCATED OVER THE NORTHEASTERN STATES ON SUNDAY EVENING. THE TROUGH IS EXPECTED TO CONTINUE LIFTING NORTHEASTWARD WITH RIDGING BUILDING OVERHEAD FROM THE WEST AND SOUTH FOR MONDAY AND TUESDAY. WE ARE ANTICIPATING A FAIR AMOUNT OF MID LEVEL CLOUDINESS ALONG WITH SOME STRATOCUMULUS FOR SUNDAY NIGHT INTO MONDAY MORNING, THEN A GENERAL DECREASE IN CLOUD COVER. CONDITIONS ARE EXPECTED TO REMAIN MARGINALLY STABLE FOR MONDAY AND TUESDAY WITH JUST A SLIGHT CHANCE OF SHOWERS AND THUNDERSTORMS ON TUESDAY AFTERNOON, MAINLY ON THE NORTHWESTERN EDGE OF OUR FORECAST AREA FROM BERKS COUNTY INTO THE LEHIGH VALLEY AND THE POCONOS. HIGH TEMPERATURES SHOULD BE MAINLY IN THE MIDDLE 80S ON MONDAY AND IN THE UPPER 80S ON TUESDAY WITH AN INCREASE IN HUMIDITY AS THE SURFACE FLOW VEERS FROM THE NORTHEAST AND EAST TO THE SOUTH. IT CONTINUES TO APPEARS AS THOUGH WEDNESDAY WILL BE THE HOTTEST DAY OF THE NEW WEEK. A PIECE OF THE HOT AIR FROM THE GREAT PLAINS IS FORECAST TO DRIFT EASTWARD AND IT SHOULD AFFECT OUR REGION AT THAT TIME. TEMPERATURES AT THE 850 HPA LEVEL ARE FORECAST TO RISE AROUND 18C OR 19C. THE INCREASE IN HUMIDITY SHOULD PREVENT TEMPERATURES FROM RISING TO THEIR DRY ADIABATIC POTENTIAL. WE WILL CONTINUE TO PREDICT MAXIMUM TEMPERATURES MOSTLY IN THE LOWER 90S. IT NO LONGER LOOKS AS THOUGH WE WILL REACH HEAT INDEX VALUES OF 100 FROM THE URBAN CORRIDOR SOUTHEASTWARD. PEAK HEAT INDEX VALUES ARE NOW FORECAST TO BE MOSTLY IN THE MIDDLE 90S, SO THE MENTION WILL BE REMOVED FROM THE HAZARDOUS WEATHER OUTLOOK PRODUCT. WE WILL MENTION A CHANCE OF THUNDERSTORMS MOVING INTO OUR REGION FROM THE NORTHWEST ON WEDNESDAY. HOWEVER, A BIT OF A CAP MAY PREVENT THE ACTIVITY FROM BECOMING WIDESPREAD AT THAT TIME. THE GUIDANCE IS COMING TOGETHER WITH A COLD FRONTAL PASSAGE ON THURSDAY. WE WILL MENTION A CHANCE OF SHOWERS AND THUNDERSTORMS FOR WEDNESDAY NIGHT INTO THURSDAY AHEAD OF AND WITH THE BOUNDARY. ALSO, WE ARE SEEING A TREND TOWARD CONSENSUS ON DRY AIR BUILDING INTO OUR REGION FROM THE NORTHWEST FOR FRIDAY AND SATURDAY. DAYTIME HIGHS ARE ANTICIPATED TO RETURN TO THE MIDDLE 80S AT MOST LOCATIONS. && .AVIATION /20Z SATURDAY THROUGH THURSDAY/... THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY AND SURROUNDING AREAS. HIGH PRESSURE OFF THE NEW ENGLAND COAST IS EXPECTED TO MAINTAIN AN EAST-SOUTHEAST FLOW OF AROUND 10 KT OVER THE TAF SITES INTO THE EVENING HOURS. THEN AS WEAK LOW PRESSURE MOVES NORTH NEAR THE COAST LATE TONIGHT AND SUNDAY, THE WIND DIRECTION IS EXPECTED TO SHIFT TO THE NORTHEAST WITH A SLIGHT DECREASE IN SPEED AS THE GRADIENT RELAXES JUST A BIT. THE PERSISTENT CLOUD COVER OVER THE REGION WILL CONTINUE THROUGH MOST OF SUNDAY, BUT CEILING HEIGHTS WON`T BE LOW ENOUGH TO CAUSE ANY CONCERN TO THE AVIATION COMMUNITY. THERE COULD BE A FEW LIGHT SPRINKLES FROM TIME TO TIME....AND PATCHY FOG CANNOT BE COMPLETELY RULED OUT..BUT THE CHANCE OF EITHER ONE ISN/T HIGH ENOUGH TO WARRANT INCLUSION IN THE TAFS ATTM. THE ONLY EXCEPTION IS ACY WHICH MAY BE CLOSE ENOUGH TO THE LIGHT RAIN SHOWERS MOVING NORTH ALONG THE COAST LATE THIS AFTERNOON. A TEMPO GROUP HAS BEEN ADDED TO THE ACY. OUTLOOK... SUNDAY NIGHT THROUGH TUESDAY...MAINLY VFR. TUESDAY NIGHT AND WEDNESDAY...MAINLY VFR. POSSIBLE LATE NIGHT AND EARLY MORNING MVFR OR IFR CONDITIONS IN LOW CLOUDS, FOG AND HAZE. A CHANCE OF AFTERNOON THUNDERSTORMS. WEDNESDAY NIGHT AND THURSDAY...MVFR AND IFR CONDITIONS AT TIMES IN SHOWERS AND THUNDERSTORMS. && .MARINE... SEAS AND WINDS ARE EXPECTED TO REMAIN BELOW SCA CRITERIA. SEAS AROUND FOUR FEET ARE LIKELY TOMORROW ON THE OCEAN WITH AN EASTERLY FLOW. WIND GUSTS AROUND 20 KNOTS ARE POSSIBLE ON THE OCEAN SUNDAY AFTERNOON. OUTLOOK... SUNDAY NIGHT THROUGH THURSDAY...NO MARINE HEADLINES ARE ANTICIPATED. && .PHI WATCHES/WARNINGS/ADVISORIES... PA...NONE. NJ...NONE. DE...NONE. MD...NONE. MARINE...NONE. && $$ SYNOPSIS...IOVINO NEAR TERM...GAINES SHORT TERM...GAINES LONG TERM...IOVINO AVIATION...IOVINO/MIKETTA MARINE...GAINES/IOVINO

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