Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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000 FXUS61 KPHI 190244 AFDPHI AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MOUNT HOLLY NJ 944 PM EST THU DEC 18 2014 .SYNOPSIS...
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A LOW PRESSURE SYSTEM OVER PRINCE EDWARD ISLAND WILL TRACK SLOWLY TO THE NORTHEAST. HIGH PRESSURE OVER THE NORTHERN GREAT LAKES WILL MOVE INTO THE OHIO VALLEY OVERNIGHT. LOW PRESSURE IS EXPECTED TO FORM OVER THE GULF STATES FRIDAY NIGHT AND TRACK ACROSS GEORGIA SATURDAY. A COLD FRONT MAY MOVE THROUGH THE EASTERN SEABOARD ON CHRISTMAS EVE.
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&& .NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
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SINCE THE TRUNDLING CLOSED LOW PRESSURE SYSTEM FROM LAST WEEK, THE NORTHEASTERN CONUS HAS NOT BEEN ABLE TO SHAKE THE PLETHORA OF LOW CLOUDINESS STUCK UNDERNEATH THE INVERSION, EVEN AFTER CHANGING AIR MASSES. TONIGHT SEEMS NOT MUCH DIFFERENT. IN ADDITION, WE DO HAVE SOME MID TO HIGH LEVEL CLOUDS MOVING THROUGH OUR CWA ASSOCIATED WITH A WEAKENING SHORT WAVE. WHILE 88DS ARE SHOWING PCPN ALOFT, NONE IS MAKING IT TO THE GROUND. THE FREEZING SNIZZLE IN UPSTATE NEW YORK (DONT RECALL THIS HAPPENING TWICE IN TWO CONSECUTIVE WEEKS) APPEARS TO NOT BE GETTING CLOSE TO OUR POCONOS. FOR THE OVERNIGHT UPDATE, WE DID INCREASE CLOUD COVER AND BUMPED UP TEMPS, ESPECIALLY IN THE NWRN TWO THIRDS OF OUR CWA WHERE WE ARE SOLIDLY OVERCAST UPSTREAM. THE SOUTHEASTERN THIRD, THERE ARE SOME LOW CLOUDS BREAK, SO KEPT THOSE MINS SIMILAR, BUT SHOWED MORE OF A LATE AT NIGHT SPIRAL.
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&& .SHORT TERM /6 AM FRIDAY MORNING THROUGH 6 PM FRIDAY/...
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LATEST WRF, RAP SHOWING MORE MOISTURE TRAPPED UNDERNEATH THE INVERSION ON FRIDAY WITH CONVECTIVE TEMPS WITHIN REACH. WE MADE IT CLOUDIER. LAST WEEK, WE FOUND A WAY TO STILL MAKE MAX TEMPS IN SPITE OF THE CLOUDS, SO LEFT THEM THE SAME.
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&& .LONG TERM /FRIDAY NIGHT THROUGH THURSDAY/... MID-LEVEL FLOW THE NEXT COUPLE OF DAYS IS RATHER FLAT THOUGH A CHANGE TO THAT PATTERN APPEARS LIKELY BY THE END OF THE WEEKEND. A DEEP TROUGH EMERGES ACROSS THE CENTRAL U.S. BY TUESDAY AS MULTIPLE PACIFIC NORTHWEST WAVES ROUND THE BASE OF THE TROUGH AND ACROSS OUR REGION...WE ARE HEADING FOR A VERY UNSETTLED PERIOD BY EARLY NEXT WEEK. FRIDAY NIGHT - SATURDAY...LOOKS DRY. FRIDAY SHOULD BE DOMINATED BY GREAT LAKES HIGH PRESSURE WHICH SHOULD YIELD PARTY CLOUDY SKIES. SATURDAY NIGHT AND SUNDAY...AN INVERTED TROUGH MAY THROW BACK SOME MOISTURE ACROSS THE AREA AS A WEAK WAVE OF LOW PRESSURE MOVES WELL OFFSHORE OF OUR REGION. ONLY HAVE SLIGHT CHANCE POPS ACROSS THE NORTHEASTERN PORTION OF THE CWA AS THAT LOOKS LIKE THE MOST FAVORABLE LOCATION FOR THE TONGUE TO MOISTURE TO REACH. GIVEN THE OVERNIGHT TIMING PRECIP COULD FALL AS RAIN SNOW MIX OR ALL SNOW. MONDAY - TUESDAY...LOW PRESSURE MOVES OFF THE CAROLINA COAST AND OUT TO SEA ON TUESDAY. THIS LOW WILL HELP LIFT A WARM FRONT ASSOCIATED WITH A LARGE AND DEVELOPING LOW PRESSURE SYSTEM OVER THE MIDDLE OF THE CONUS INTO THE AREA. ONSHORE FLOW AHEAD OF THE SYSTEM AND WARM AIR MOVING IN WITH THE FRONT WILL ALLOW FOR A WARMING LOW-LEVEL THERMAL PROFILE SO PRECIP SHOULD BE PRIMARILY LIQUID. MID-RANGE CHANCE POPS WILL PERSIST MONDAY...MONDAY NIGHT...AND TUESDAY. WEDNESDAY...STILL WATCHING A LARGE LOW PRESSURE FORM TO OUR WEST AND TRACK INTO THE GREAT LAKES REGION ON WEDNESDAY. THIS WOULD KEEP OUR REGION UNDER A WARMING THERMAL PROFILE WITH A LOT OF MOISTURE TO WORK WITH. WHAT IS INTERESTING WITH THE LATEST MODEL RUNS IS HOW THEY ARE SEEMINGLY WEAKENING THE PRIMARY LOW AS IT MOVES INTO THE LAKES ALLOWING FOR ANOTHER, STRONGER, PIECE OF PAC NW ENERGY TO PRODUCE CYCLOGENESIS ACROSS THE MID-ATLANTIC. IT APPEARS THAT CHRISTMAS EVE WL BE A DAY W/ MOISTURE, WINDS, AND POSSIBLY CONVECTION. LKLY POPS ARE IN THE FCST. THURSDAY...CHRISTMAS DAY - DEEP LAYER ZONAL FLOW WILL FILL IN ACROSS THE AREA. DRY CONDITIONS XPCTD AS THE COLD FRONT SHOULD BE E OF THE AREA. A DEEP STACKED LOW WILL BE OVER THE EASTERN GREAT LAKES. RIGHT NOW "COOL AND BRZY" COULD BE THE WX WORDS FOR THE DAY. && .AVIATION /03Z FRIDAY THROUGH TUESDAY/...
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THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY AND SURROUNDING AREAS. 00Z TAFS WILL BE VFR. TONIGHT...A VFR CIG IS FORECAST. FOR KACY AND KMIV THIS IS MAINLY DUE TO MID LEVEL CLOUDS. AT THE KPHL AIRPORTS, ITS A COMBINATION OF A STRATOCU CIG AROUND 4K AND THE MID LEVEL CLOUD DECK. AT KRDG AND KABE ITS MAINLY A STRATOCU DECK AT AROUND 3500 FEET. THERE WILL BE MVFR CIGS AT AIRPORTS FARTHER TO THE NORTHWEST AND MIGHT MAKE IT INTO THESE LATTER TERMINALS. WE DID AMEND SOME OF THE TERMINALS DOWNWARD. WEST TO NORTHWEST WINDS SHOULD AVERAGE LESS THAN 10 KNOTS. FRIDAY...GOING MORE PESSIMISTICALLY WITH VFR CIGS AND EXPECTING A STRATOCU CIG TO EITHER PERSIST NORTHWEST TO TERMINALS, OR DEVELOP ELSEWHERE DURING THE DAY. MVFR CIGS POSSIBLE HIER TERRAIN AIRPORTS. NORTHWEST WINDS SHOULD BE SLIGHTLY LESS THAN TODAY WITH SUSTAINED SPEEDS AROUND 10 KNOTS AND PEAK GUSTS CLOSER TO 20 KNOTS. LATE IN THE DAY WE ARE PREDICTING THE GUSTS AND VFR CIGS SHOULD NO LONGER OCCUR. OUTLOOK... FRIDAY NIGHT - SATURDAY...VFR. NORTHWEST WINDS VEER TOWARDS THE NORTH-NORTHEAST BY SATURDAY. SUNDAY - MONDAY...SUB-VFR POSSIBLE WITH SCATTERED RAIN/SNOW SHOWERS. TUESDAY...VFR.
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&& .MARINE...
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THE SMALL CRAFT ADVISORY NORTHERN WATERS WILL BE ALLOWED TO EXPIRE AT 10 PM. GUIDANCE IS SHOWING A PAINFULLY SLOW, BUT STEADY DROP OFF IN WINDS. GUSTS NEAR OR ABOVE 20 KT WILL BE POSSIBLE THROUGH THE OVERNIGHT. SUB SMALL CRAFT ADVISORY CONDITIONS EXPECTED ON FRIDAY. OUTLOOK... FRIDAY NIGHT...MOSTLY SUB-ADVISORY CONDITIONS ARE EXPECTED. SOME NORTHWEST WIND GUSTS COULD STILL BE IN THE 20 PLUS KNOT RANGE, THOUGH. CONFIDENCE: ABOVE AVERAGE. SATURDAY - SUNDAY...SUB-SCA EXPECTED FOR THE MOST PART. SEAS REMAIN AROUND 3 TO 4 FEET. CONFIDENCE: AVERAGE TO SLIGHTLY BELOW AVERAGE. MONDAY - TUESDAY...SCA CONDITIONS SHOULD PRESENT THEMSELVES LATER ON MONDAY UNDER A STRENGTHENING EASTERLY FLOW AND BUILDING SEAS. CONFIDENCE: AVERAGE.
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&& .PHI WATCHES/WARNINGS/ADVISORIES...
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PA...NONE. NJ...NONE. DE...NONE. MD...NONE. MARINE...NONE.
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&& $$ SYNOPSIS...GIGI NEAR TERM...GIGI SHORT TERM...99 LONG TERM...99 AVIATION...GIGI/99 MARINE...GIGI/99

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