Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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000 FXUS61 KPHI 221750 AFDPHI AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MOUNT HOLLY NJ 1250 PM EST THU JAN 22 2015 .SYNOPSIS... WEAK LOW PRESSURE IN NORTHEASTERN PENNSYLVANIA WILL MERGE WITH A SEAWARD DEVELOPING LOW PRESSURE OFF THE MID ATLANTIC COAST. HIGH PRESSURE IN THE CENTRAL PLAINS WILL SLIDE INTO OUR REGION THIS AFTERNOON AND TONIGHT. THIS HIGH PRESSURE WILL MOVE THROUGH ON FRIDAY BEFORE GIVING WAY TO A LOW PRESSURE SYSTEM TRACKING UP THE COAST ON SATURDAY. ON SUNDAY A LOW PRESSURE SYSTEM WILL TRACK ACROSS THE GREAT LAKES AND INTO OUR REGION ON MONDAY. THIS LOW PRESSURE WILL DEPART THE REGION BY THE MIDDLE OF NEXT WEEK. && .NEAR TERM /UNTIL 6 PM THIS EVENING/...
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LOW LEVEL MOISTURE REMAINED IN PLACE OVER MUCH OF OUR FORECAST AREA AT 1230 PM. A WESTERLY SURFACE WIND HAD DEVELOPED AND A SLOW LIFTING AND BREAKING OF THE LOW CLOUD COVER WILL CONTINUE THROUGH THE BALANCE OF THE AFTERNOON. BREAKS IN THE CLOUD COVER HAD ALREADY WORKED THEIR WAY OVER NORTHERN NEW JERSEY AND OVER THE UPPER DELMARVA. RADAR CONTINUED TO SHOW SOME SNOW FLURRIES OVER BERKS COUNTY AND CHESTER COUNTY. AS THE AIR GRADUALLY DRIES, FLURRIES SHOULD DISSIPATE. MAXIMUM TEMPERATURES SHOULD BE MAINLY IN THE 30S.
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&& .SHORT TERM /6 PM THIS EVENING THROUGH 6 AM FRIDAY/... TSECTIONS AND LAPSE RATES SUGGEST THAT CLEARING WILL BE FAIRLY QUICK LATE THIS AFTERNOON/EVENING. SO A MOSTLY CLEAR NIGHT IS EXPECTED. A LIGHT NW WIND. PATCHY FOG IS NOT IN THE FCST TONIGHT BUT MAYBE IT WILL BE FROSTY DUE TO STILL SOMEWHAT ELEVATED DEW POINTS. TEMPS/DEWS/WINDS ARE A 50 50 BLEND OF THE 00Z/22 NAM/GFS MOS GUIDANCE WITH SOME COOLING OF THOSE BLENDED TEMPS BY 2 DEGREES OR SO IN THE PINE BARRENS OF SNJ AND ALSO IN THE COOLER RADIATORS OF BUCKS AND MONTGOMERY COUNTIES IN PA WHERE A LITTLE SNOW ACCUMULATED. ITS DEBATABLE HOW MUCH OF THAT SNOW WILL REMAIN BY NIGHTFALL. THESE FORECAST LOWS ARE NEAR NORMAL FOR THE DATE. && .LONG TERM /FRIDAY THROUGH WEDNESDAY/... FRIDAY: HIGH PRESSURE WILL BUILD BACK INTO THE REGION RESULTING IN A MOSTLY SUNNY DAY. DID NOT GO AS WARM AS THE NEW MAV AND MET RUNS FOR TEMPERATURES BUT THIS COULD BE POSSIBLE GIVEN AMPLE SUNSHINE. FRIDAY NIGHT THROUGH SATURDAY NIGHT: LOW PRESSURE WILL TRACK UP THE EAST COAST. THE SPREAD IN THE OPERATIONAL MODEL RUNS AND THE VARIOUS ENSEMBLES HAVE DECREASED. THIS INCLUDES SOME OF THE WESTERN ECMWF ENSEMBLES, THROUGH EXAMINATION OF THE MEAN. THE 18Z GEFS ALSO APPEAR TO HAVE A TIGHTER SPREAD COMPARED TO PREVIOUS RUNS. THE NAM AND GFS REMAIN FURTHER OFFSHORE AND LESS DEVELOPED WITH THE ECMWF TRENDING IN THIS DIRECTION AS WELL. HOWEVER THE CMC AND UKMET CONTINUE TO BE CLOSER TO THE COAST WITH HIGHER QPF. THE OVERALL TREND OVERNIGHT WAS TO SHOW A MORE DISORGANIZED LOW PRESSURE SYSTEM. IN TERMS OF WEATHER, SNOW OR THE CHANCES FOR MIXED PRECIPITATION WILL BEGIN TO INCREASE FROM SOUTH TO NORTH FRIDAY NIGHT WITH OVERRUNNING WAA. MODERATE PRECIPITATION WILL LIKELY OCCUR WITHIN THIS PRECIPITATION SHIELD WITH THE BULK OF SNOWFALL ACCUMULATIONS. THERMAL PROFILES SUGGEST THAT THE DELMARVA AND COASTAL NJ WILL CHANGE TO RAIN BY SATURDAY MORNING, WITH SLEET MIXED AS WELL. THIS IS DUE TO THE POTENTIAL OF MID-LEVEL WARMING IS GREATER THAN IN THE AIR TEMPERATURE CLOSER TO THE SURFACE. LIGHTER PRECIPITATION WILL BE NOTED NW OF PHL FURTHER FROM THE LOW. AFTER THIS PUSH OF PRECIPITATION A DRY SLOT OR LINGERING LIGHT RAIN OR A RAIN/SNOW MIX ( NW OF PHL) SHOULD CONTINUE INTO THE AFTERNOON, SURFACE WARMING IS GREATER THAN MID-LEVEL WARMING AT THIS POINT. A CCB MAY STILL FORM ON THE BACKEND OF THE LOW PRESSURE SYSTEM WITH A PERIOD OF SNOW OR RAIN CHANGING TO SNOW. THE MORE DISORGANIZED TRENDS HAVE DECREASED THE CHANCES OF THIS TO OCCUR. OUR QPF FORECAST TOOK ELEMENTS OF THE WPC, SREF AND THE ECMWF. ALSO KEEPING IN MIND THE MORE BULLISH QPF SOLUTIONS OF THE UKMET AND CMC. A ZONE FROM THE LEHIGH VALLEY TO INTERSTATE 295 HAVE THE HIGHEST CHANCES OF SEEING SNOW TOTALS FROM 3-4 INCHES, WITH LOWER AMOUNTS SURROUNDING THIS ZONE. THIS IS DUE TO A QUICK CHANGEOVER SE AND LESS QPF NW. FOR TEMPERATURES STAYED CLOSER TO THE MODELED TWO METER TEMPERATURES WHICH RESPECTIVE MODELS HAD PRECIPITATION IN THE FORECAST. SUNDAY: A TEMPORARY BREAK BETWEEN SYSTEMS WITH A MIX OF CLOUDS AND SUN. TEMPERATURES COULD BE COOLER THAN ENSEMBLES/MEX GUIDANCE DUE TO SNOW COVER. SUNDAY NIGHT THROUGH MONDAY NIGHT: ANOTHER SYSTEM DIVES SOUTHEAST FROM THE GREAT LAKES REACHING OUR REGION BY MONDAY MORNING. THIS LOOKS TO BE ANOTHER CLIPPER TYPE SYSTEM WHICH THEN TRANSFERS IT`S ENERGY TO A COASTAL LOW. THERE IS A HIGHER DEGREE OF SPREAD COMPARED TO THE SATURDAY SYSTEM IN THE ENSEMBLES WITH THIS FEATURE IN THE OVERALL TRACK AND HOW MUCH IT CAN STRENGTHEN ONCE IT REACHES THE EAST COAST. FOR NOW CARRYING A CHANCE OF SNOW ACROSS THE REGION WITH SOME MIX ACROSS THE COAST CHANGING TO SNOW FOR SUNDAY NIGHT THROUGH MONDAY NIGHT. THOUGHT THE 00Z GFS WAS TO STRONG WITH THIS FEATURE ALLOWING FOR EXCESSIVE WAA, OUR PRECIPITATION TYPE FORECAST WAS CONSIDERABLY MORE WINTRY IN LINE WITH THE ECMWF. TUESDAY AND WEDNESDAY: INDICATIONS CONTINUE TO A FAIRLY POTENT ARCTIC AIR MASS COMING IN BEHIND THE DEPARTING SYSTEM. SEVERAL GEFS MEMBERS ARE QUITE POTENT DELIVERING AN AIR MASS WITH 850 MB TEMPS AROUND -20C AND MOST OPERATIONAL MODELS ARE AT LEAST -10C. UNDERCUT ENSEMBLE GUIDANCE. A FRESH SNOW COVER COULD ALSO MAKE THIS PERIOD RATHER CHILLY. SKIES WILL BE MOSTLY CLEAR WITH A NORTHWEST FLOW. && .AVIATION /18Z THURSDAY THROUGH TUESDAY/...
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THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY AND SURROUNDING AREAS. THE LOW CONDITIONS WILL CONTINUE TO LIFT AND BREAK SLOWLY DURING THE AFTERNOON HOURS. IT APPEARS AS THOUGH OUR TAF SITES SHOULD ALL IMPROVE INTO THE VFR CATEGORY BY ABOUT 2000Z TO 2100Z WITH CEILINGS LIFTING INTO THE 3500 TO 4000 FOOT RANGE. THE CLOUD COVER IS EXPECTED TO DISSIPATE FOR TONIGHT WITH A MAINLY CLEAR SKY ANTICIPATED ALONG WITH NO VISIBILITY RESTRICTIONS. A WEST TO NORTHWEST WIND AT 6 TO 12 KNOTS IS FORECAST THROUGH THIS AFTERNOON. WIND SPEEDS ARE EXPECTED TO DIMINISH TO 4 TO 8 KNOTS FOR TONIGHT. OUTLOOK... FRIDAY: VFR, INCREASING CLOUDS FRIDAY NIGHT THROUGH SATURDAY NIGHT: IFR/LIFR CEILINGS AND VISIBILITIES IN SNOW AND RAIN. LOWEST CEILINGS FROM 08-14Z SATURDAY, ACCUMULATING SNOW AT PHL EXPECTED. MORE RAIN SOUTHEAST OF PHL AND SNOW NORTHWEST OF PHL. NORTHWEST GUSTS UP TO 20 KNOTS SATURDAY AFTERNOON AND NIGHT. SUNDAY: VFR. SUNDAY NIGHT AND MONDAY: INCREASING CLOUDS, POTENTIAL LOWER CEILINGS DUE TO SNOW LATE SUNDAY NIGHT AND MONDAY.
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&& .MARINE... LIGHT W-NW WIND INCREASING THIS AFTERNOON AND TONIGHT WITH NW GUSTS TO 20 KT. SMALL CHANCE OF BRIEF GUSTS 25 KT THIS EVENING VCNTY DELAWARE BAY. NO SCA ATTM...THROUGH DAYBREAK FRIDAY. WAVE HEIGHTS ON OUR OCEAN WATERS SHOULD BE 2 TO 4 FEET THROUGH DAYBREAK FRIDAY. OUTLOOK... FRIDAY AND FRIDAY NIGHT: SUB SCA SEAS AND WINDS INCREASING FRIDAY NIGHT. SATURDAY AND SATURDAY NIGHT: SCA SEAS AND GUSTS BY AFTERNOON. WINDS FROM THE EAST SHIFTING TO NORTHWEST BY SATURDAY NIGHT. SOME GALE FORCE GUSTS POSSIBLE SATURDAY NIGHT. SUNDAY AND SUNDAY NIGHT: SEAS AND WIND GUSTS DECREASING BELOW SCA CRITERIA BY SUNDAY AFTERNOON. MONDAY: AN SCA MAY BE NEEDED AS AN ALBERTA CLIPPER REDEVELOPS OFF THE MID ATLANTIC COAST. && .PHI WATCHES/WARNINGS/ADVISORIES... PA...NONE. NJ...NONE. DE...NONE. MD...NONE. MARINE...NONE. && $$ SYNOPSIS...DRAG/GAINES NEAR TERM...IOVINO SHORT TERM...DRAG LONG TERM...GAINES AVIATION...GAINES/IOVINO MARINE...DRAG/GAINES

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