Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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920 FXUS61 KPHI 270434 AFDPHI AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MOUNT HOLLY NJ 1234 AM EDT WED APR 27 2016 .SYNOPSIS...
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A COLD FRONT WILL PUSH SOUTH OF OUR AREA THROUGH WEDNESDAY MORNING AND THEN STALL. LOW PRESSURE WILL TRACK ALONG THIS FRONT TO OUR SOUTH THURSDAY INTO FRIDAY. HIGH PRESSURE CENTERED NEAR HUDSON BAY CANADA FRIDAY INTO SATURDAY WILL BUILD DOWN INTO OUR AREA THROUGH MUCH OF SUNDAY. LOW PRESSURE THOUGH IN THE OHIO VALLEY MONDAY SLOWLY MOVES CLOSER TO OUR AREA TUESDAY.
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&& .NEAR TERM /UNTIL 6 AM THIS MORNING/...
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THE COLD FRONT WAS LOCATED ACROSS TALBOT COUNTY AND CAROLINE COUNTY IN MARYLAND, AND ACROSS SOUTHERN SUSSEX COUNTY IN DELAWARE AROUND MIDNIGHT. THE BOUNDARY WILL CONTINUE TO SINK TO THE SOUTH. SCATTERED SHOWERS WILL RIDE ALONG THE FRONT AND THEY MAY CONTINUE TO AFFECT OUR SOUTHERN COUNTIES OVERNIGHT. LOW CLOUDS HAVE OVERSPREAD MUCH OF OUR REGION IN THE NORTHEAST FLOW. THE CLOUDS MAY BEGIN TO ERODE FROM THE NORTH TOWARD MORNING. MINIMUM TEMPERATURES ARE EXPECTED TO FAVOR THE 40S IN OUR NORTHERN AND CENTRAL COUNTIES AND THE LOWER 50S IN THE SOUTH. THERE MAY BE SOME READINGS IN THE MIDDLE AND UPPER 30S IN THE ELEVATED TERRAIN UP NORTH.
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&& .SHORT TERM /6 AM THIS MORNING THROUGH 6 AM THURSDAY/...
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THE COLD FRONT IS EXPECTED TO DECELERATE AS IT MOVES SOUTHWARD INTO SRN VA AND NC ON WEDNESDAY. MEANWHILE, HIGH PRESSURE CENTERED NEAR THE CANADIAN NORTHWEST PASSAGES WILL BUILD SEWD INTO THE NORTHEAST STATES. THE LATEST GUIDANCE SHOWS DRIER AIR WITH THIS HIGH ADVECTING SOUTH INTO THE LEHIGH VALLEY AND NW NJ DURING THE MORNING BUT STRUGGLE TO ADVANCE FARTHER TO THE SOUTH DURING THE AFTERNOON. THIS APPEARS A RESULT OF THE WINDS ACROSS SE PA/S NJ/DELMARVA REMAINING VEERED OUT OF THE NE. FORECAST SOUNDINGS ACROSS THE SRN HALF OF THE CWA, ESPECIALLY FROM THE 12Z NAM, INDICATE MOISTURE WILL REMAIN TRAPPED UNDERNEATH THE BOUNDARY LAYER DUE TO ONSHORE FLOW OFF THE OCEAN. THE MARINE STRATOCU WILL BE STUBBORN TO ERODE THE FARTHER SOUTH YOU GO. HIGHS RANGE FROM THE MU50S IN THE DELMARVA AND COASTAL NJ TO LM60S IN E PA AND IN C/NW NJ.
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&& .LONG TERM /THURSDAY THROUGH WEDNESDAY/...
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THE SYNOPTIC PATTERN IS FORECAST TO BE COMPRISED OF A STRONG CLOSED LOW NEAR THE CANADIAN MARITIMES WEDNESDAY NIGHT AND THURSDAY THAT THEN SHIFTS EASTWARD. THIS ALLOWS CYCLONIC FLOW TO OCCUR ACROSS OUR REGION FOR A TIME. THERE ARE SOME POCKETS OF ENERGY FORECAST TO EVOLVE AROUND THIS LARGE TROUGH, ALLOWING LOW PRESSURE TO TRACK ALONG A STALLED FRONTAL BOUNDARY TO OUR SOUTH THURSDAY THEN ANOTHER ONE EARLY NEXT WEEK. THIS WILL LEAD TO SOME UNSETTLED WEATHER AT TIMES, MOSTLY ON THURSDAY AND THEN AGAIN EARLY NEXT WEEK. THE AMOUNT OF PRECIPITATION AND CLOUD COVER WILL IMPACT THE TEMPERATURES, ESPECIALLY GIVEN THROUGH SUNDAY STRONG HIGH PRESSURE IS ANCHORED WELL TO OUR NORTH. WE USED A MODEL/CONTINUITY BLEND THROUGH FRIDAY, THEN BLENDED IN THE 12Z WPC GUIDANCE THEREAFTER. SOME ADJUSTMENTS WERE THEN MADE FOLLOWING ADDITIONAL COLLABORATION WITH OUR NEIGHBORING OFFICES. FOR WEDNESDAY NIGHT AND THURSDAY...A POTENT CLOSED LOW CENTERED NEAR THE CANADIAN MARITIMES WILL RESULT IN CYCLONIC FLOW ACROSS THE AREA. A STALLED FRONT TO OUR SOUTH WILL CONTINUE WITH ENERGY TRAVERSING IT, WITH THE MAIN ENERGY BACK INTO THE PLAINS. SURFACE HIGH PRESSURE TRIES TO BUILD DOWN INTO OUR AREA AT FIRST, HOWEVER A LEAD IMPULSE WILL DRIVE WAA AND OVERRUNNING INTO OUR AREA DURING THURSDAY. HOWEVER, THERE IS SOME UNCERTAINTY ON THE NORTHERN EXTENT AND ALSO COVERAGE OF THE SHOWERS ASSOCIATED WITH THIS GIVEN POTENTIALLY MUCH DRIER AIR ADVECTING SOUTHWARD. LOOKS LIKE THE HIGHEST CHCS FOR SHOWERS IS IN THE SOUTHERN HALF OF THE AREA AND THIS IS WHERE THE HIGHEST POPS ARE CURRENTLY PLACED. GIVEN A NORTHEASTERLY LOW- LEVEL FLOW AND THE PROSPECTS FOR A DECENT AMOUNT OF CLOUD COVER, WE ARE ANTICIPATING THURSDAY TO BE ON THE COOL SIDE. FOR FRIDAY THROUGH SUNDAY...SURFACE LOW FEATURE TO OUR SOUTH OVERALL SHOULD BE SHIFTING OFFSHORE TO START FRIDAY. AS ADDITIONAL ENERGY AMPLIFIES ACROSS THE PLAINS INTO SUNDAY, STRONG AND EXPANSIVE HIGH PRESSURE AT THE SURFACE CENTERED NEAR HUDSON BAY WILL WEDGE DOWN INTO OUR AREA ESPECIALLY SATURDAY AND MUCH OF SUNDAY. THIS WILL RESULT IN NORTHEASTERLY FLOW OVERALL IN THE LOWER LEVELS, WITH COOL TEMPERATURES CONTINUING ALTHOUGH SOME MODERATION SHOULD OCCUR SUNDAY AWAY FROM THE COAST. LOW PRESSURE MIGRATING FROM THE CENTRAL PLAINS TO THE UPPER OHIO VALLEY SUNDAY INTO MONDAY WILL PUSH A WARM FRONT TOWARD OUR AREA LATER SUNDAY. SOME WAA AND ISENTROPIC LIFT MAY BE ENOUGH TO PRODUCE SOME SHOWERS ESPECIALLY LATE SUNDAY. FOR MONDAY AND TUESDAY...THE EVOLUTION OF AN INITIAL CLOSED LOW WELL TO OUR WEST, AS IT MAY OPEN UP INTO THE EAST, DURING EARLY NEXT WEEK WILL DETERMINE OUR SENSIBLE WEATHER. SOME GUIDANCE INDICATES A FASTER EVOLUTION TO THIS FEATURE WHICH WOULD END ANY PRECIPITATION CHCS SOONER. THE FLOW OVERALL LOOKS LIKE IT COULD BE BLOCKY ENOUGH TO RESULT IN A SLOWER EASTWARD SHIFT OF THE SURFACE LOW, THEREFORE WE FAVORED WPC GUIDANCE THAT SHOWS THE LOW ARRIVING DURING TUESDAY. AS A RESULT, A POTENTIALLY UNSETTLED REGIME DURING THIS TIME FRAME.
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&& .AVIATION /06Z WEDNESDAY THROUGH SUNDAY/...
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THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY AND SURROUNDING AREAS. REST OF TONIGHT...IFR CIGS MOST AREAS OVERNIGHT WITH NE WIND. WEDNESDAY...IFR AND MVFR CIGS TO START IMPROVE FROM NORTH TO SOUTH TO CIGS BETWEEN 3000-4000 FT DURING MIDDAY OR THE AFTERNOON WITH A N-NE WIND GUSTS UNDER 15 KT DURING MORNING BECOMING LIGHT AND VARIABLE DURING THE AFTERNOON. OUTLOOK... WEDNESDAY NIGHT AND THURSDAY...POTENTIALLY LOWERING TO MVFR/IFR CONDITIONS ALONG WITH SHOWERS. FRIDAY...MVFR CEILINGS POSSIBLE TO START, OTHERWISE VFR. SATURDAY AND SUNDAY...VFR OVERALL, HOWEVER LOWER CEILINGS MAY DEVELOP LATER SUNDAY WITH SOME SHOWERS.
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&& .MARINE...
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SCA ATLC WATERS. SEAS 4 TO 7 FT. SEAS AND WINDS SLOWLY SUBSIDE WEDNESDAY. COMPETING SOUTHERLY AND NORTHEAST SWELL GROUPS OVERNIGHT SHOULD BECOME NORTHEAST DOMINANT FOR A WHILE BEFORE THE NORTHEAST COMPONENT WEAKENS DURING WEDNESDAY AFTERNOON. OUTLOOK... WEDNESDAY NIGHT THROUGH SUNDAY...THE WINDS OVERALL ARE ANTICIPATED TO BE BELOW 25 KNOTS, HOWEVER THE SEAS SHOULD BUILD TO ABOUT 5 FEET ON THE ATLANTIC COASTAL WATERS THURSDAY INTO THE WEEKEND WITH AN ONSHORE FLOW.
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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 EARLY THIS MORNING FOR ANZ450>455.
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&& $$ SYNOPSIS...GORSE NEAR TERM...IOVINO SHORT TERM...KLEIN LONG TERM...GORSE AVIATION...DRAG/GORSE MARINE...DRAG/GORSE

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