Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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000 FXUS61 KPHI 260759 AFDPHI AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MOUNT HOLLY NJ 359 AM EDT SUN OCT 26 2014 .SYNOPSIS...
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A COLD FRONT WILL MOVE OFF THE NORTHERN MID-ATLANTIC COAST THIS MORNING. HIGH PRESSURE BUILDS IN FROM THE WEST THIS AFTERNOON AND TONIGHT. THE HIGH WILL RIDGE INTO THE AREA MONDAY AND MOVE OFFSHORE MONDAY NIGHT. A WARM FRONT IS EXPECTED TO PASS THROUGH THE AREA TUESDAY FOLLOWED BY THE PASSAGE OF A COLD FRONT WEDNESDAY. HIGH PRESSURE BRIEFLY RETURNS THURSDAY. A COLD FRONT IS EXPECTED TO MOVE THROUGH THE NORTHEAST ON FRIDAY WITH A LOW PRESSURE SYSTEM FORMING ALONG IT. CANADIAN HIGH PRESSURE WILL LIKELY BUILD INTO THE EASTERN UNITED STATES NEXT WEEKEND.
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&& .NEAR TERM /UNTIL 6 PM THIS EVENING/...
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SURFACE COLD FRONT IS JUST NOW BEGINNING TO CROSS THE REGION FROM NORTHWEST TO SOUTHEAST. AN AREA OF ENHANCED SHOWER ACTIVITY, ASSOCIATED WITH THE PASSING TROUGH, SHOULD STAY MOSTLY TO OUR NORTH THIS MORNING, WITH A FEW ISOLATED SHOWERS POSSIBLE ACROSS OUR EXTREME NORTHERN ZONES. OTHERWISE, SURFACE RIDGING WILL ONCE AGAIN BUILD IN FROM THE WEST-SOUTHWEST LATER TODAY. THE PRESSURE GRADIENT BEGINS TO REALLY TIGHTEN THIS MORNING WITH A BLAST OF COLD AIR ALOFT FROM THE NORTHWEST. WE SHOULD BE ABLE TO MIX UPWARDS OF AT LEAST 850MB WHERE 30 TO 35 KNOTS EXISTS TO BRING MOST OF THAT MOMENTUM TO THE SURFACE...GUSTS INTO THE LOW 30MPH RANGE IS EXPECTED LATE THIS MORNING INTO THE EARLY AFTERNOON WITH DECREASING GUSTS DURING THE LATE AFTERNOON AND EVENING HOURS. TEMPERATURES TODAY WILL BE A FEW DEGREES COOLER THAN ON SATURDAY. THE AIRMASS ALOFT WILL BE ABOUT 3 TO 5 DEGREES COOLER AT 925MB THIS AFTERNOON COMPARED TO YESTERDAY. WE EXPECT FULL MIXING UNDER MOSTLY SUNNY SKIES AND WITH A STRONGER DOWNSLOPING COMPONENT. WE WENT SLIGHTLY ABOVE GUIDANCE THIS AFTERNOON AND INTO THE MID TO UPPER-60S IN MOST PLACES...WARMER INTO OUR SOUTHERN ZONES.
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&& .SHORT TERM /6 PM THIS EVENING THROUGH 6 AM MONDAY/...
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WE SHOULD START TO LOSE THE GUSTS BY LATE THIS EVENING THOUGH WE KEEP THE TIGHTER PRESSURE GRADIENT IN PLACE. WINDS DO NOT LOOK TO FULLY DECOUPLE TONIGHT SO RADIATIVE COOLING UNDER CLEARING SKIES WILL NOT BE STRONG, THOUGH IT WILL OCCUR TO A DEGREE. THERE COULD BE ANOTHER SHOT OF WEAK COLD AIR ADVECTION LATE TONIGHT AND GIVEN THE DRIER AIRMASS IN PLACE WE SHOULD BE ABLE TO COOL INTO UPPER- 30S AND THE LOW-40S IN A LOT OF PLACES...RIGHT AROUND AVERAGE.
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&& .LONG TERM /MONDAY THROUGH SATURDAY/...
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HIGH PRESSURE WILL BE CENTERED ALONG THE SOUTHEAST COAST ON MONDAY. NEAR NORMAL TEMPS ARE EXPECTED UNDER A WEST-NORTHWEST FLOW REGIME. WITH THE UPPER JET NEARBY, COULD SEE SOME CIRRUS SPILL INTO THE AREA BUT MOSTLY SUNNY SKIES SHOULD PREVAIL. LOW-LEVEL WINDS BACK OUT OF THE SOUTHWEST MONDAY NIGHT AS HIGH SHIFTS OFFSHORE. A WARM FRONT WILL SUBSEQUENTLY LIFT NORTHWARD THRU THE REGION LATE MONDAY NIGHT INTO TUESDAY. ASSUMING FULL MIXING, 925 MB TEMPS 20-21C WOULD SUPPORT MAX TEMPS IN THE LOW 80S. HOWEVER, DO NOT EXPECT FULL MIXING GIVEN THE LOW SUN ANGLE THIS TIME OF YEAR. WENT SLIGHTLY ABOVE MAV/MET GUIDANCE, YIELDING MAX TEMPS IN THE MID 70S WITH A FEW WARMER SPOTS FLIRTING WITH 80F. EXCEPT FOR GED ON THE 14TH, NONE OF THE CLIMATE SITES HAS REACHED 80F THIS MONTH. LOW PRESSURE IS FORECAST TO DEEPEN LATE TUESDAY INTO WEDNESDAY AS IT LIFTS NORTHEASTWARD INTO NORTHERN QUEBEC. MODELS CONTINUE TO REMAIN IN GOOD AGREEMENT REGARDING TIMING OF THE COLD FRONT WITH THIS SYSTEM. FROPA EXPECTED ON WEDNESDAY. BEST CHANCE FOR SHOWERS ARE ON WEDNESDAY BUT SHOWERS MAY ARRIVE AS EARLY AS LATE TUESDAY NIGHT WHEN REGION BECOMES POSITIONED IN RIGHT ENTRANCE REGION OF AN UPPER-LEVEL JET STREAK. THE COLD FRONT SHOULD BE OFFSHORE BY WEDNESDAY EVENING. COLDER AND DRIER AIR ADVECTS INTO THE MID-ATLANTIC REGION. LEANED TOWARD THE WARMER SIDE OF GUIDANCE FOR MIN TEMPS WEDNESDAY NIGHT WITH BREEZY NORTHWEST WINDS LIMITING RADIATIONAL COOLING. QUIET WX PATTERN THURSDAY-THURSDAY NIGHT WITH HIGH PRESSURE BUILDING OVERHEAD. TEMPS NEAR NORMAL. PAC NW ENERGY IS EXPECTED TO DIG SOUTHEASTWARD AS IT MOVES TOWARD THE MS VALLEY, LEADING TO AMPLIFICATION OF THE LARGE SCALE TROUGH OVER THE EASTERN US LATE IN THE WEEK. MEANWHILE, A NORTHERN STREAM SHORTWAVE TROUGH IS FORECAST TO DIVE SOUTHEASTWARD TOWARD THE GREAT LAKES AND POSSIBLY PHASE WITH THE PAC NW SYSTEM. A SOMEWHAT LARGE MODEL SPREAD CONTINUES TO EXIST FOR FRIDAY AND SATURDAY AS RELATIVELY SMALL DIFFERENCES BETWEEN THE STRENGTH AND POSITION OF BOTH SYSTEMS GROW EXPONENTIALLY IN THESE TYPES OF PHASING SCENARIOS. THE 00Z OPERATIONAL ECMWF BACKED OFF FROM ITS PREVIOUS 12Z RUN WHICH HAD A MUCH STRONGER SOUTHERN SYSTEM THAT WOULD HAVE YIELDED A WASH OUT NEXT WEEKEND AS A DEEP COASTAL LOW MOVES UP THE EASTERN SEABOARD. LOOKING UPSTREAM, THE RIDGE OVER THE ROCKIES IS FAVORED TO PROGRESS EASTWARD AS TROUGHING DEVELOPS OVER THE WESTERN CONUS NEXT WEEKEND. THIS WOULD SUPPORT A PROGRESSIVE DOWNSTREAM TROUGH OVER THE EAST, WHICH IS NOW PREDICTED BY THE LATEST ECMWF/GFS ENSEMBLE MEANS. ITS LOOKING MORE OPTIMISTIC THAN BEFORE FOR A MOSTLY DRY UPCOMING WEEKEND.
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&& .AVIATION /08Z SUNDAY THROUGH THURSDAY/...
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THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY AND SURROUNDING AREAS. TODAY - TONIGHT...VFR. COLD FRONT WILL PUSH THROUGH EARLY THIS MORNING AND THE WINDS BACK TO THE WEST-NORTHWEST. EXPECTING GUSTS THIS MORNING UPWARDS OF 30 KNOTS AND THEY SHOULD DIMINISH DURING THE LATE AFTERNOON/EARLY EVENING HOURS THOUGH STILL IN THE LOW-20S. SHOULD COMPLETELY LOSE THE GUSTS SHORTLY AFTER SUNSET WITH WEST-NORTHWEST WINDS AROUND 8 KNOTS. HIGH CONFIDENCE. OUTLOOK... MONDAY THROUGH TUESDAY EVENING...VFR AND LIGHT WINDS. LATE TUESDAY NIGHT AND WEDNESDAY...CHANCE OF SHRA WITH A COLD FRONT. BRIEF MVFR POSSIBLE BUT PREDOMINATELY VFR. WEDNESDAY NIGHT AND THURSDAY...VFR AND LIGHT NW WINDS.
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&& .MARINE...
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TODAY...STRONG SCA GUSTS EXPECTED BY LATE MORNING. COLD FRONT WILL WORK ITS WAY THROUGH THIS MORNING AND WINDS BACK TO THE WEST-NORTHWEST AND INCREASE UNDER A TIGHTENING PRESSURE GRADIENT. THERE COULD BE THE OCCASIONAL GALE GUST ON OUR SOUTHERN WATERS, AT THE MOUTH OF THE BAY, BUT DURATION AND COVERAGE DON`T LOOK TO WARRANT WARNINGS. HIGH CONFIDENCE, LOW ON GALE FORMATION/COVERAGE. TONIGHT...SCA CONDITIONS EXPECTED BUT WITH DECREASING WINDS. WINDS CONTINUE OUT OF THE WEST-NORTHWEST WITH SEAS AROUND 2 TO 4 FEET. HIGH CONFIDENCE. OUTLOOK... MONDAY AND MONDAY NIGHT...LIGHT WINDS AND CALM SEAS. TUESDAY AND WEDNESDAY...SW FLOW STRENGTHENS TUESDAY. WINDS AND SEAS MAY APPROACH MARGINAL SCA TUESDAY NIGHT AND WEDNESDAY MORNING BUT CONFIDENCE IN THIS HAPPENING IS LOW THIS FAR OUT. WINDS BECOME NW BEHIND A COLD FRONT WEDNESDAY AFTERNOON AND WEAKEN. SEAS MAY REMAIN ELEVATED NEAR 4-5 FT THOUGH, NECESSITATING A SCA. WEDNESDAY NIGHT AND THURSDAY...LIGHT NW WINDS.
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&& .FIRE WEATHER...
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WE WILL CONTINUE TO MONITOR THE OUTSIDE POSSIBILITY OF AN ENHANCED FIRE SPREAD THREAT FOR TODAY. THE WINDS AND GUSTS SHOULD EASILY BE NEAR 30 MPH FOR A TIME THIS AFTERNOON, BUT THE RELATIVE HUMIDITIES, ALTHOUGH DECREASING THROUGHOUT THE DAY, SHOULD REMAIN ABOVE 30 PERCENT. THE RECENT RAINS OF THE PAST WEEK HAVE ALSO ALLOWED FOR WETTER FINE FUELS. AFTER COORDINATION WITH OUR SURROUNDING OFFICES AND STATE FIRE OFFICIALS WE HAVE DECIDED TO FORGO ANY HEADLINES AND SPECIAL STATEMENTS FOR TODAY.
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&& .PHI WATCHES/WARNINGS/ADVISORIES...
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PA...NONE. NJ...NONE. DE...NONE. MD...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 6 AM EDT MONDAY FOR ANZ450>455. SMALL CRAFT ADVISORY FROM 8 AM THIS MORNING TO 9 PM EDT THIS EVENING FOR ANZ430-431.
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&& $$ SYNOPSIS...KLEIN NEAR TERM...HEAVENER SHORT TERM...HEAVENER LONG TERM...KLEIN AVIATION...HEAVENER/KLEIN MARINE...HEAVENER/KLEIN FIRE WEATHER...HEAVENER/KLEIN

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