Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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043 FXUS61 KPHI 100827 AFDPHI AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MOUNT HOLLY NJ 327 AM EST WED FEB 10 2016 .SYNOPSIS...
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LOW PRESSURE ACROSS NEW ENGLAND WILL CONTINUE TO MOVE NORTHEAST AWAY FROM THE REGION TODAY. HIGH PRESSURE WILL BUILD EASTWARD INTO THE REGION THURSDAY AND THEN MOVE THROUGH ON FRIDAY BEFORE GIVING WAY TO A ARCTIC COLD FRONTAL BOUNDARY BY THE END OF THE WEEK. ON SUNDAY, ANOTHER AREA OF HIGH PRESSURE WILL BUILD SOUTHWARD INTO THE REGION AS LOW PRESSURE FORMS ACROSS THE SOUTHERN UNITED STATES BY MONDAY. THIS AREA OF LOW PRESSURE WILL THEN TRACK UP THE EAST COAST ON TUESDAY.
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&& .NEAR TERM /UNTIL 6 PM THIS EVENING/...
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EARLY IN THE DAY, THE MAIN STORY WILL BE ICY SPOTS ON ROADS AND WALKWAYS AS THERE WAS STANDING WATER IN MANY LOCATIONS LAST EVENING, AND TEMPERATURES HAVE ALREADY DROPPED BELOW FREEZING FOR MOST LOCATIONS. WE WILL CONTINUE THE SPECIAL WEATHER STATEMENT (SPS) WARNING ABOUT THIS THROUGH AT LEAST THE MORNING COMMUTE. UPPER LEVEL SHORT WAVE TROUGH LIFTS THROUGH THE REGION EARLY IN THE DAY. AS A RESULT, WE SHOULD SEE LINGERING SNOW SHOWERS MOVE OUT OF THE REGION BY MID DAY. IN THE LOW LEVELS, NORTHWESTERLY FLOW DEVELOPS, RESULTING IN LOW LEVEL COLD AIR ADVECTION. AS SUCH, EXPECT HIGHS WILL ONLY BE IN THE 30S FOR MOST OF THE REGION, WHILE THE POCONOS MAY NOT GET OUT OF THE 20S.
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&& .SHORT TERM /6 PM THIS EVENING THROUGH 6 AM THURSDAY/...
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A SECOND, LESS DEFINED, MID AND UPPER LEVEL SHORT WAVE TROUGH WILL APPROACH FROM THE WEST OVERNIGHT. CONTINUED THE TREND OF A SMALL CHANCE OF SNOW SHOWERS. HOWEVER, I AM NOT EXPECTING MUCH IN THE WAY OF ACCUMULATING SNOW FOR TWO REASONS. FIRST, THE REGION WILL GENERALLY BE UNDER THE LEFT REAR QUADRANT OF AN UPPER LEVEL JET THROUGH THIS TIME, WHICH SHOULD LIMIT LIFT. SECONDLY, IN ADDITION TO THE COLD AIR ADVECTION, ALSO EXPECT CONSIDERABLE DRY AIR ADVECTION IN THE BOUNDARY LAYER (SINGLE DIGIT DEW POINTS ARE POSSIBLE BY EARLY THURSDAY MORNING), SO MOISTURE WILL BE LIMITED AS WELL.
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&& .LONG TERM /THURSDAY THROUGH TUESDAY/...
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THE EXTENDED WILL LIKELY FEATURE BOTH THE PROSPECTS FOR THE COLDEST AIR OF THE SEASON CENTERED ON SUNDAY MORNING AND A STRENGTHENING LOW PRESSURE SYSTEM TRACKING UP THE EAST COAST EARLY NEXT WEEK. THURSDAY AND THURSDAY NIGHT: HIGH PRESSURE WILL GRADUALLY BUILD EASTWARD FROM THE OHIO VALLEY TOWARD THE REGION. OUR REGION WILL CONTINUE TO SEE STRONG CAA WITH A WEST-NORTHWEST WIND OFF THE EASTERN GREAT LAKES. BUFKIT ANALYSIS SHOWS THAT STRONG WIND GUSTS MAY REACH 30 MPH AT TIMES. ALSO LOW LEVEL LAPSE RATES WILL ALSO STEEPEN DURING THE DAY WHICH COULD BE ENOUGH TO DEVELOP SOME SCATTERED SNOW SHOWERS AND FLURRIES DURING THE DAY WITH THE HIGHEST COVERAGE AIDED BY ELEVATION ACROSS EASTERN PA AND NW NJ. WITH THE STRONG CAA PUSH WILL TREND TEMPERATURES A BIT LOWER THAN MET/MAV AND ENSEMBLE GUIDANCE. THE PRESSURE GRADIENT WILL RELAX THURSDAY NIGHT ALLOWING FOR WINDS TO DECREASE AS A HIGH PRESSURE SYSTEM MOVES INTO THE REGION. CONDITIONS LOOK MORE FAVORABLE FOR RADIATIONAL COOLING COMPARED TO TONIGHT. FRIDAY AND SATURDAY: HIGH PRESSURE WILL MOVE THROUGH THE REGION ON FRIDAY. THIS HIGH PRESSURE SYSTEM WILL GIVE WAY TO ANOTHER ARCTIC COLD FRONT. THE FRONT MOVES THROUGH THE REGION FRIDAY NIGHT AND SATURDAY. TRENDS WITH BOTH THE OPERATIONAL AND ENSEMBLE GUIDANCE FORM A COASTAL LOW PRESSURE SYSTEM SOUTHEAST OF US AND OFFSHORE, SO THE POSSIBILITY OF A COASTAL LOW NEAR US IN THIS PERIOD HAS GREATLY DECREASED. IT WILL BE A VERY COLD AND WINDY PERIOD WITH ANOTHER ROUND OF NW FLOW SNOW SHOWERS AND FLURRIES BEHIND THE FRONT WITH THE HIGHEST COVERAGE IN THE HIGH TERRAIN AREAS IN EASTERN PA AND NW NJ, SIMILAR TO THE MIDDLE OF THIS WEEK. BUFKIT ANALYSIS SHOWS THE POTENTIAL FOR MIXING AGAIN SATURDAY SIMILAR TO THURSDAY SO WIND GUSTS COULD BE QUITE STRONG, OVER 30 MPH AGAIN. SATURDAY NIGHT THROUGH SUNDAY NIGHT: ANOTHER POTENT AREA OF ARCTIC HIGH PRESSURE WILL BUILD INTO THE REGION WITH THE COLDEST SHOT OF AIR OF THE SEASON SO FAR. 850 MB LOOK TO DIVE BELOW -25C ACROSS MOST OF REGION AS CURRENTLY MODELED. AS IN OTHER PERIODS WILL CONTINUE TO NUDGE TEMPERATURES A COUPLE OF DEGREES COOLER THAN MOST ENSEMBLE GUIDANCE. NORTHWEST WINDS ALTHOUGH NOT AS STRONG AS SATURDAY WILL LIKELY TO BELOW ZERO WIND CHILLS, PUSHING ADVISORY CRITERIA IN SPOTS FROM -10 IN THE DELMARVA TO LOWER THAN -20 IN THE POCONOS. PRESIDENTS DAY THROUGH TUESDAY: HIGH PRESSURE WILL GRADUALLY MOVE EAST OF THE REGION AND WILL GIVE WAY TO A STORM SYSTEM THAT IS CURRENTLY MODELED TO FORM ACROSS THE SOUTHERN UNITED STATES MONDAY AND TRACK UP THE EAST COAST TUESDAY. TWO CAMPS ARE CURRENTLY PRESENT WITH THE TRACK OF THE STORM SYSTEM. THE MAIN DIFFERENCES BETWEEN THE TWO SOLUTIONS ARE THE SPEED OF VARIOUS SHORTWAVES WHICH ULTIMATELY DEVELOP THE STORM ACROSS THE SOUTHERN UNITED STATES AND THE DEGREE OF MID-LEVEL RIDGING MODELS DEVELOP AHEAD OF IT. THE UKMET AND ECMWF ARE SLOWER WITH OVERALL TIMING ALLOWING FOR MID-LEVEL RIDGING TO FORM OVER THE REGION AND IN NEW ENGLAND. THIS ALLOWS FOR AS WARMER AND FURTHER WEST TRACK WHICH WOULD RESULT IN MAINLY A RAIN EVENT. THE FASTER GFS AND CMC SOLUTIONS SHIFT THE DEVELOPING SYSTEM FURTHER EAST AND ARE FASTER, TRACKING IT UP THE EAST COAST WHICH WOULD BE A SNOWIER OUTCOME. FOR NOW WILL TAKE A MIDDLE OF THE ROAD APPROACH, THIS BRINGS SNOW IN MONDAY WHICH GRADUALLY MIXES AND CHANGES TO RAIN BY TUESDAY. ENSEMBLE DATA IS CURRENTLY LEANING TOWARD THE WARMER WESTWARD TRACK. HOWEVER, GIVEN THIS IS SEVERAL DAYS A LOT OF ENSEMBLE SPREAD IS STILL PRESENT AND THE VARIOUS FEATURES INVOLVED WILL NOT EVEN SAMPLED BY OBSERVATIONAL DATA FOR SEVERAL MORE DAYS.
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&& .AVIATION /08Z WEDNESDAY THROUGH SUNDAY/...
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THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY AND SURROUNDING AREAS. WE ARE EXPECTING CEILINGS TO RISE TO VFR CONDITIONS BY 12Z OR SHORTLY THEREAFTER. THOUGH WE COULD SEE PERSISTENT MID LEVEL CEILINGS (5000 TO 8000 FT AGL) THROUGH THE DAY AND EVEN TONIGHT, DO NOT EXPECT CEILINGS TO DROP BACK TO MVFR ONCE THEY IMPROVE LATER THIS MORNING. OUTLOOK... THURSDAY: MAINLY VFR, SOME BRIEF MVFR RESTRICTIONS IN ISOLATED SNOW SHOWERS AND FLURRIES. NORTHWEST WINDS 15-25 KNOTS WITH HIGHER GUSTS. THURSDAY NIGHT AND FRIDAY: VFR. NORTHWEST WINDS UNDER 15 KNOTS SHIFTING TO SOUTHWEST ON FRIDAY FRIDAY NIGHT AND SATURDAY: MAINLY VFR, POSSIBILE MVFR RESTRICTIONS IN SCATTERED SNOW SHOWERS. NORTHWEST WINDS INCREASING SATURDAY FROM 15-25 KNOTS WITH HIGHER GUSTS ON SATURDAY. SUNDAY...VFR WITH DIMINISHING NORTHWEST WINDS.
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&& .MARINE...
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SCA CONDITIONS FOR WINDS WILL CONTINUE ON THE COASTAL WATERS AND THE DELAWARE BAY TODAY. SEAS HAVE BEEN STEADILY DECREASING OVERNIGHT, AND MAY DROP BELOW 5 FT FOR MUCH OF THE DAY. TONIGHT...HAVE EXTENDED THE SCA THROUGH THE OVERNIGHT HOURS AND DELAYED THE START TIME OF THE GALE WATCH. MODEL SOUNDINGS FROM NAM, RAP, AND GFS AND THE PROBABILISTIC WIND SPEED GUIDANCE OF THE NAEFS AND GEFS SHOW A MINIMAL CHANCE FOR GALES OVERNIGHT. IN ORDER TO GET GALE FORCE WINDS, THERE WOULD HAVE TO BE A VERY DEEP MIXING LAYER WHICH SEEMS UNLIKELY GIVEN THE PERSISTENT MID LEVEL CLOUD COVER. OUTLOOK... THE GALE WATCH HAS BEEN EXTENDED INTO THURSDAY EVENING. FAIRLY HIGH CONFIDENCE IS PRESENT FOR NORTHWEST WIND GUSTS NEAR AND JUST OVER GALE FORCE THROUGHOUT MUCH OF THURSDAY AND INTO THE EARLY EVENING. SEAS WILL ALSO BE AROUND FIVE FEET BEFORE DECREASING LATER THURSDAY NIGHT. SCA NORTHWEST WINDS WILL CONTINUE INTO EARLY FRIDAY. AFTER A LULL WITH SEAS AND WINDS FOR A GOOD PART OF FRIDAY AND MAYBE INTO EARLY SATURDAY AN ARCTIC COLD FRONT WILL LEAD TO RAMP UP ON SATURDAY. ANOTHER ROUND OF NORTHWEST GALE FORCE GUSTS ARE LIKELY SATURDAY AFTERNOON AND EVENING WITH SEAS NEAR AND OVER FIVE FEET. STRONG NORTHWEST WIND GUSTS BELOW GALE FORCE WILL LINGER INTO SUNDAY. IN ADDITION TO THE THREAT FOR GALES SEVERAL ROUNDS OF FREEZING SPRAY CONDITIONS ARE POSSIBILE AS WELL WITH THE FIRST ROUND WEDNESDAY NIGHT INTO THURSDAY AND THE POTENTIAL FOR MODERATE TO HEAVY FREEZING SPRAY THIS WEEKEND.
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&& .TIDES/COASTAL FLOODING...
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WITH A SHIFT TO OFF SHORE FLOW, AND LOWER ASTRONOMICAL TIDES, COASTAL FLOODING CONCERNS ARE WINDING DOWN, WITH TWO EXCEPTIONS. FIRST, FOR THE NORTHERN NEW JERSEY SHORE, WINDS WERE SLOWER TO SHIFT TO WESTERLY AS COMPARED TO THE REST OF THE REGION. AS A RESULT, WATER LEVELS AT SANDY HOOK AS WE APPROACH LOW TIDE ARE RUNNING SLIGHTLY HIGHER THAN GUIDANCE. THUS, COULD SEE ONE MORE HIGH TIDE CYCLE WITH MINOR COASTAL FLOODING THIS MORNING. FOR CAROLINE, TALBOT, AND QUEEN ANNE`S COUNTY IN MD, EXPECT MINOR COASTAL FLOODING WITH THE HIGH TIDE CYCLE THAT WILL OCCUR BY 9 AM THIS MORNING.
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&& .CLIMATE... NEAR RECORD COLD IS EXPECTED FOR PORTIONS OF OUR AREA SUNDAY MORNING AND BY FAR THE COLDEST AIR OF THE SEASON SO FAR. 2015-16 SO FAR RER 14TH ABE 8......... -1 1979 ACY 10........ -6 1979 PHL 12........ +2 1979 ILG 12........ -4 1979 RDG 10........ -4-1983 TTN 9......... 0 1916 GED 13........ -7 1979 MPO -1........ -12 1970 ADDITIONALLY...THIS WILL BE WIND DRIVEN COLD WITH MANY AREAS EXPERIENCING WIND CHILL VALUES OF 15 TO 20 BELOW ZERO...POSSIBLY 25 BELOW IN THE HILLS AND MOUNTAINS OF NORTHWEST NEW JERSEY AND NORTHEAST PENNSYLVANIA. && .PHI WATCHES/WARNINGS/ADVISORIES...
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PA...NONE. NJ...COASTAL FLOOD ADVISORY FROM 8 AM THIS MORNING TO 1 PM EST THIS AFTERNOON FOR NJZ012>014-020-026. DE...NONE. MD...COASTAL FLOOD ADVISORY UNTIL 9 AM EST THIS MORNING FOR MDZ015- 019-020. MARINE...GALE WATCH FROM THURSDAY MORNING THROUGH THURSDAY EVENING FOR ANZ430-431-450>455. SMALL CRAFT ADVISORY UNTIL 6 AM EST THURSDAY FOR ANZ430-431- 450>455.
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&& $$ SYNOPSIS...GAINES NEAR TERM...JOHNSON SHORT TERM...JOHNSON LONG TERM...GAINES AVIATION...GAINES/JOHNSON MARINE...GAINES/JOHNSON TIDES/COASTAL FLOODING... CLIMATE...

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