Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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000 FXUS61 KPHI 070914 AFDPHI AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MOUNT HOLLY NJ 414 AM EST SUN FEB 7 2016 .SYNOPSIS...
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LOW PRESSURE WILL DEEPEN RAPIDLY OFF THE SOUTHEAST COAST TODAY AND TRACK NORTHEASTWARD OFF THE MID-ATLANTIC AND NORTHEAST COAST TONIGHT INTO MONDAY. ANOTHER LOW PRESSURE SYSTEM IS FORECAST TO DEVELOP IN ITS WAKE NEAR THE MID-ATLANTIC COAST MONDAY NIGHT AND INTO TUESDAY. ARCTIC HIGH PRESSURE IS THEN EXPECTED TO BUILD IN FROM THE NORTH AND WEST DURING THE LATTER PART OF THE WEEK. ANOTHER COLD FRONT PASSING THROUGH THE AREA WILL REINFORCE THE SUPPLY OF ARCTIC AIR INTO OUR REGION NEXT WEEKEND.
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&& .NEAR TERM /UNTIL 6 PM THIS EVENING/...
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ANOTHER PLEASANT FAIR WEATHER DAY IS EXPECTED FOR THE REGION WITH DRY CONDITIONS AND AMPLE SUNSHINE THROUGH THE DAY; ALTHOUGH, SOME CIRRUS WILL BEGIN TO ADVANCE IN ACROSS THE AREA AHEAD OF AN APPROACHING STORM SYSTEM ORGANIZING OFF THE SOUTHEAST COAST. WINDS WILL START OUT LIGHT AND VARIABLE IN THE MORNING AND EVENTUALLY TAKE ON A NORTH-NORTHEAST DIRECTION AS THE DAY WEARS ON, REMAINING UNDER 10MPH. TEMPERATURES WILL END UP BEING A LITTLE BIT ABOVE EARLY FEBRUARY NORMALS, AND WE GENERALLY USED A BLEND OF MET/MAV GUIDANCE. HIGHS ARE EXPECTED TO REACH MOSTLY INTO THE MIDDLE AND UPPER 40S, EXCEPT SLIGHTLY COOLER READINGS OVER THE SOUTHERN POCONOS.
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&& .SHORT TERM /6 PM THIS EVENING THROUGH 6 AM MONDAY/...
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THICKENING AND LOWERING CLOUDS WILL BE ARRIVING ACROSS THE REGION FROM SOUTHEAST TO NORTHWEST AS OFFSHORE LOW PRESSURE TRACKS NORTHEASTWARD OUT TO SEA AND AWAY FROM THE SOUTHEASTERN SEABOARD. LATEST 0Z MODEL GUIDANCE KEEPS THIS STRONG LOW PRESSURE FAR ENOUGH TO THE EAST TO KEEP OUR REGION PRECIP-FREE DESPITE THE INCREASING CLOUD COVER. THE EXCEPTION TO THIS MIGHT BE FAR EASTERN AREAS NEAR THE COASTS OF NEW JERSEY AND PERHAPS THE DELAWARE BEACHES WHERE WE HAVE KEPT SOME SLIGHT CHANCE TO CHANCE POPS OVERNIGHT FOR THE POSSIBILITY OF LIGHT RAIN OR SNOW. OTHERWISE NORTH-NORTHEAST WINDS ARE EXPECTED ACROSS THE REGION THROUGH THE NIGHT WITH SPEEDS INCREASING TO BETWEEN 10 TO 15 MPH. SOME GUSTS TO AROUND 25 MPH ARE POSSIBLE INTO EARLY MORNING MONDAY NEAR THE COASTS OF NEW JERSEY AND DELAWARE. OVERNIGHT LOW TEMPERATURES SHOULD BE A COUPLE OF DEGREES MILDER THAN LAST NIGHT, WITH READINGS DROPPING OFF INTO THE UPPER 20S AND LOWER 30S FOR MOST OF THE REGION.
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&& .LONG TERM /MONDAY THROUGH SATURDAY/...
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THE SPREAD IN THE MODEL GUIDANCE HAS DECREASED FOR THE 00Z RUN WITH THE TRACK OF STRONG OFFSHORE LOW ON MONDAY. MANY OF THE PREVIOUSLY WESTERN OUTLIER SUCH AS THE NAM AND GEM HAVE TRENDED FARTHER TO THE EAST AND IS MORE IN LINE WITH THE ECMWF/GFS SOLUTIONS. INTERESTINGLY, MANY OF THE 03Z SREF ARW/NMB MEMBERS ARE SHOWING A SEVERAL INCHES OF SNOW FOR US WITH THIS FIRST SYSTEM. ASIDE FROM THE SREF, THERE IS NOW LITTLE SUPPORT FOR OUR IMPACT FROM THIS STORM BEING MUCH MORE THAN SOME LIGHT SNOW OR FLURRIES ALONG THE COAST ON MONDAY. EVEN WITH THE INCREASING SUPPORT THAT THIS STORM WILL MISS OUR AREA, THIS POWERFUL STORM STILL BEARS WATCHING IN THE UNLIKELY EVENT THAT IT TRENDS CLOSER TO THE COAST. ONLY A 50 MILE (100 MILE) SHIFT IN THE TRACK BACK TO THE WEST COULD RESULT IN ADVISORY (WARNING) LEVEL SNOWFALL CLOSE THE COAST ACCORDING TO THE 00Z GEM. THOUGH VERY UNLIKELY, WE`VE SEEN CRAZIER THINGS. AS MENTIONED YESTERDAY, MODEL CONSENSUS FOR DAYS LEADING UP TO THE PAST TWO STORMS (THE LATE JANUARY BLIZZARD AND THE A COUPLE OF DAYS AGO) HAD A DISTINCT EASTWARD BIAS IN THE TRACK. OUR ATTENTION THEN TURNS UPSTREAM TO A DIGGING UPPER LOW OVER THE GREAT LAKES REGION ON MONDAY. THERE IS GOOD AGREEMENT AMONG GUIDANCE FOR LIGHT SNOW TO OVERSPREAD THE AREA FROM THE SOUTHWEST MONDAY EVENING AS A LEADING SHORTWAVE TROUGH MOVES THROUGH THE MID ATLANTIC. THERE IS STILL UNCERTAINTY IF THE ONSET OF THE LIGHT SNOW WILL BE IN TIME TO FOR THE MONDAY AFTERNOON/EVENING COMMUTE OR IF IT HOLDS OFF UNTIL AFTER. AS THE PRIMARY SURFACE LOW MOVES OVER SOUTHERN VA, MODELS ARE SHOWING IT TRANSFERRING ITS ENERGY TO A SECONDARY LOW THAT DEVELOPS OFF THE COAST. THE MODELS HAVE COME INTO BETTER AGREEMENT WITH THIS MILLER-B COASTAL LOW ORGANIZING A BIT TOO LATE AND TOO FAR OFFSHORE TO BRING HEAVIER SNOW BACK INLAND INTO THE FORECAST AREA. INSTEAD THEY SHOW AN EXTENDED PERIOD OF MAINLY LIGHT SNOW MONDAY NIGHT THROUGH TUESDAY NIGHT IN ASSOCIATION WITH THE WEAKER PRIMARY LOW. ALTHOUGH PARTIAL THICKNESS NOMOGRAMS IMPLY ALL SNOW, THE BOUNDARY LAYER IS MARGINALLY SUPPORTIVE OF SNOW, SO RAIN AND/OR MELTING OF SNOW ON CONTACT WOULD CUT DOWN ON TOTALS AT LOWER ELEVATIONS... ESPECIALLY WHEN PRECIP INTENSITY IS LIGHT. THERE STILL ISN`T ENOUGH FORECAST CONFIDENCE TO GO WITH MUCH MORE THAN A WIDESPREAD 1-3 INCHES OF SNOWFALL FOR THIS EVENT. HOWEVER, WE NEED TO WATCH FOR THE POTENTIAL FOR LOCAL ENHANCEMENT OF THE SNOWFALL LATE MONDAY NIGHT INTO TUESDAY, ESPECIALLY IF THERE IS CSI PRESENT WITHIN THE INVERTED TROUGH AXIS (I.E., A NORLUN TROUGH). THE PLACEMENT OF THE HEAVIER BAND, IF IT DEVELOPS, IS STILL HIGHLY UNCERTAIN BUT THE TREND HAS BEEN TO PLACE IT SOUTHWARD OVER SOUTHEASTERN PA-CENTRAL NJ. SOME SHIFT IT EVEN FARTHER SOUTH INTO THE DELMARVA-SOUTHERN NJ ALTHOUGH WARM SURFACE TEMPS COULD LIMIT THE POTENTIAL FOR HIGHER ACCUMULATIONS THIS THIS FAR SOUTH. THE 00Z GFS IS QUITE MORE BULLISH WITH SNOWFALL AMOUNTS AS IT HOLDS MORE ENERGY BACK WITH THE PRIMARY LOW. THIS GFS RUN ALSO KEEPS ACCUMULATING SNOW OVER OUR AREA FOR 60 HOURS, WHICH SEEMS DOUBTFUL. WILL KEEP A CHANCE FOR LIGHT SNOW SHOWERS IN THE FORECAST FOR WEDNESDAY AS THE UPPER LOW OPENS UP AND PROGRESSES THRU THE AREA. A COLD FRONT WILL MOVE THROUGH THE REGION LATE WEDNESDAY. IN ITS WAKE, THE LEADING EDGE OF ARCTIC AIR ADVANCES INTO THE REGION. TEMPS THURSDAY AND FRIDAY WILL STRUGGLE TO GET ABOVE FREEZING IN THE COASTAL PLAIN AND LIKELY REMAIN IN THE 20S NORTH AND WEST OF THE FALL LINE. A REINFORCING SHOT OF ARCTIC AIR IS FORECAST TO TAKE AIM FOR THE MID-ATLANTIC AND NORTHEAST STATES AS A PIECE OF THE WELL- KNOWN POLAR VORTEX DIGS INTO SOUTHEASTERN CANADA. TEMPERATURES COULD BE 15-20F BELOW NORMAL FOR NEXT WEEKEND.
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&& .AVIATION /09Z SUNDAY THROUGH THURSDAY/...
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THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY AND SURROUNDING AREAS. TODAY...VFR CONDITIONS ARE EXPECTED THROUGH TODAY. MAINLY CLEAR SKIES ARE EXPECTED, WITH PERHAPS SOME CIRRUS WORKING IN ACROSS THE REGION LATE IN THE DAY. WINDS EARLY WILL START OUT CALM OR LIGHT AND VARIABLE, EVENTUALLY TAKING ON A NORTH-NORTHEAST DIRECTION WITH SPEEDS ONLY AVERAGING ABOUT 4 TO 6 KNOTS. TONIGHT...MAINLY VFR CONDITIONS THROUGH MOST OF THE NIGHT, WITH SOME POSSIBLE SUB-VFR DEVELOPING TOWARD DAYBREAK MONDAY, ESPECIALLY ACROSS EASTERN NJ DUE TO AN APPROACHING OFFSHORE STORM. CONTINUED NORTHEAST WINDS ARE EXPECTED WITH SPEEDS INCREASING OVERNIGHT TO DAYBREAK MONDAY INTO THE 10 TO 15 KNOT RANGE, WITH SOME GUSTS DEVELOPING LATE FOR EASTERN NJ TO BETWEEN 20 TO 25 KNOTS. OUTLOOK... MONDAY AND TUESDAY...PRECIP MAY OVERSPREAD THE AREA MONDAY AFTERNOON OR EVENING. IT MAY BE WARM ENOUGH AT THE ONSET TO BEGIN AS A RA/SN MIX FOR PHL AND NEARBY TERMINALS...AND RAIN AT ACY/MIV. EVENTUALLY IT WILL LIKELY TURN OVER TO SNOW FROM NW TO SE MONDAY NIGHT AND CONTINUE AT TIMES INTO TUESDAY NIGHT. RIGHT NOW, IT APPEARS THAT SNOWFALL RATES SHOULD PREDOMINATELY BE LIGHT DURING THIS EVENT BUT THERE IS A POTENTIAL FOR LOCALLY HEAVIER BANDS TO DEVELOP. THE SNOW WOULD RESULT IN PERIODS OF IFR/LIFR RESTRICTIONS. THERE IS STILL CONSIDERABLE UNCERTAINTY CONCERNING THE IMPACTS TO THE TERMINALS DURING THIS PERIOD. WEDNESDAY...LEFTOVER SNOW SHOWERS WILL TAPER OFF FROM WEST TO EAST DURING THE DAY. CONDITIONS WILL IMPROVE TO VFR AS WELL. BREEZY WLY WINDS GUSTING TO 25 KT. THURSDAY...VFR AND BREEZY NW WINDS. BREEZY NWLY WINDS GUSTING TO 30 KT.
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&& .MARINE...
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TODAY...SUB-ADVISORY CONDITIONS WILL START THE DAY FOR THE AREA WATERS, BUT WINDS WILL BEGIN TO INCREASE FROM SOUTH TO NORTH DURING THE AFTERNOON AS THE PRESSURE GRADIENT BEGINS TO TIGHTEN AHEAD OF AN APPROACHING STORM SYSTEM FROM THE SOUTH. THIS WILL LEAD TO SMALL CRAFT CONDITIONS DEVELOPING DURING THE AFTERNOON FOR OUR OCEAN WATERS AS NORTHEAST WIND GUSTS BEGIN TO REACH INTO THE 25 TO 30 KNOT RANGE. TONIGHT...AS THE LOW PRESSURE TRACKS NORTHEAST LATER TONIGHT, THE PRESSURE GRADIENT TIGHTENS EVEN FURTHER, AND WE ANTICIPATE TO REACH GALE GUSTS OF 35 KNOTS PLUS FOR OUR OCEAN WATERS. WE THEREFORE HAVE ISSUED A GALE WARNING BEGINNING AT 8PM THIS EVENING AS THE GALE GUSTS DEVELOP FROM SOUTH TO NORTH THROUGH OUR ATLANTIC COASTAL WATERS. FOR DELAWARE BAY, WE ANTICIPATE SMALL CRAFT ADVISORY WIND GUSTS OF 25 KNOTS TO ENSUE THIS EVENING AND OVERNIGHT, AND THE SCA FLAG BEGINS AT 8PM FOR THE UPPER AND LOWER BAY. OUTLOOK... MONDAY...THE GALE WATCH WAS CONVERTED TO A WARNING FOR THE COASTAL ATLANTIC WATERS FOR MONDAY. MOST GUIDANCE SHOWS THE POTENTIAL FOR FREQUENT GUSTS TO 35 KT, ESPECIALLY THE FARTHER OFFSHORE YOU GO. THE GALE WARNING IS IN EFFECT UNTIL NOON THOUGH IT MAY BE ABLE TO BE CANCELLED EARLIER FROM SOUTH TO NORTH AS THE LOW TRACKS WELL EAST OF LONG ISLAND. SCA CONDITIONS WILL LIKELY FOLLOW DURING THE AFTERNOON. MONDAY NIGHT THROUGH WEDNESDAY...ANOTHER AREA OF LOW PRESSURE WILL DEVELOP OFF THE MID-ATLANTIC COAST. AN EXTENDED PERIOD OF SCA CONDITIONS LIKELY DURING THIS TIME. IT COULD POTENTIAL REACH GALE FORCE LATE WEDNESDAY BUT UNCERTAINTY IS VERY HIGH REGARDING THE STRENGTH OF THE WINDS. THURSDAY...SOLID SCA CONDITIONS. NW WINDS BEHIND A COLD FRONT COULD APPROACH GALE FORCE.
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&& .TIDES/COASTAL FLOODING...
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***WE ARE WATCHING TWO POTENTIAL COASTAL FLOOD EVENTS NEAR THE MONDAY MORNING HIGH TIDE AND TUESDAY MORNING HIGH TIDE*** THE FLOW WILL BECOME ONSHORE THIS AFTERNOON AS HIGH PRESSURE ANCHORS OVER SOUTHEAST CANADA AND LOW PRESSURE DEVELOPS OFF THE SOUTHEAST COAST. THIS AREA OF LOW PRESSURE IS EXPECTED TO PASS WELL EAST OF OUR REGION. WITH THE AFOREMENTIONED HIGH REMAINING TO OUR NORTH, ANOTHER AREA OF LOW PRESSURE WILL DEVELOP OFF THE OUTERBANKS OF NORTH CAROLINA MONDAY NIGHT AND PASS SOUTHEAST OF OUR REGION DURING THE DAY TUESDAY. THESE TWO SYSTEMS WILL MAINTAIN AN ONSHORE COMPONENT TO THE FLOW ALONG THE COAST TO VARYING DEGREES SUNDAY THRU TUESDAY. ASTRONOMICAL TIDES WILL BE HIGH TO BEGIN WITH GIVEN THE NEW MOON TOMORROW. FOR THE MONDAY MORNING HIGH TIDE, THE THREAT OF COASTAL FLOODING WILL BE HIGHEST ALONG THE NORTHERN NJ COAST, WHERE THE GREATEST COMPONENT OF ONSHORE FLOW WILL BE PRESENT. GIVEN THE SHORT DURATION OF STRONGER ONSHORE FLOW, THE WIND BACKING FROM THE NORTHEAST TO NORTH /MORE OFFSHORE/ AS WE APPROACH HIGH TIDE, AND CONTINUED UNCERTAINTY REGARDING THE STORM TRACK, CONFIDENCE REGARDING IMPACTS IS LOW. THE LATEST INDICATION IS ANY COASTAL FLOODING WOULD BE MINOR (ADVISORY LEVEL). REGARDING THE TUESDAY MORNING HIGH TIDE, WE EXPECT STRONGER ONSHORE FLOW. ASIDE FROM A BRIEF LULL IN THIS FLOW LATE MONDAY, WE`LL HAVE HAD NEARLY 48 HOURS DURATION OF ONSHORE FLOW, WHICH WILL MAKE FOR POSITIVE TIDAL DEPARTURES TO BEGIN WITH. IN ADDITION, A MORE EASTERLY WIND WILL MAKE FOR A LONGER FETCH IN TERMS OF BUILDING WAVE ACTION. AT THIS TIME, THERE IS THE POTENTIAL FOR MORE WIDESPREAD MINOR COASTAL FLOODING ALONG THE ATLANTIC COAST AND ALSO FARTHER UP THE DELAWARE BAY. A FEW LOCATIONS ON THE ATLANTIC COAST MAY EXPERIENCE MODERATE FLOODING TUESDAY MORNING BUT CONFIDENCE IS NOT VERY HIGH YET. PLEASE STAY TUNED TO LATER FORECASTS AND POSSIBLE HEADLINES.
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&& .PHI WATCHES/WARNINGS/ADVISORIES...
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PA...NONE. NJ...NONE. DE...NONE. MD...NONE. MARINE...GALE WARNING FROM 8 PM THIS EVENING TO NOON EST MONDAY FOR ANZ450>455. SMALL CRAFT ADVISORY FROM 8 PM THIS EVENING TO 6 AM EST MONDAY FOR ANZ430-431.
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&& $$ SYNOPSIS...KLEIN NEAR TERM...KLINE SHORT TERM...KLINE LONG TERM...KLEIN AVIATION...KLEIN/KLINE MARINE...KLEIN/KLINE TIDES/COASTAL FLOODING...KLEIN/FRANCK

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