Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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000 FXUS61 KPHI 061353 AFDPHI AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MOUNT HOLLY NJ 953 AM EDT FRI MAY 6 2016 .SYNOPSIS... AN AREA OF LOW PRESSURE WILL MOVE INTO OUR AREA FROM THE SOUTHEAST LATER TODAY, THEN LINGER THROUGH SATURDAY BEFORE DISSIPATING. A COLD FRONT WILL MOVE THROUGH SUNDAY MORNING, FOLLOWING BY HIGH PRESSURE SUNDAY NIGHT INTO MONDAY BEFORE MOVING OFFSHORE. A WARM FRONT LIFTS NORTH ACROSS OUR AREA DURING TUESDAY, THEN STALLS IN OUR AREA WEDNESDAY INTO THURSDAY. && .NEAR TERM /UNTIL 6 PM THIS EVENING/...
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SOME HEAVIER SHOWERS HAVE BEEN TRAVERSING THE REGION THIS MORNING WITH SCATTERED SHOWERS CONTINUING ACROSS THE AREA. EXPECT THE HEAVIER RAIN TO CONTINUE TO PUSH TO THE WEST-SOUTHWEST AND OUT OF THE AREA THIS MORNING. LIGHT TO MODERATE RAIN SHOWERS WILL CONTINUE THROUGH THE REST OF THE DAY WITH SOME TAPERING OFF EXPECTED FROM EAST TO WEST LATER IN THE DAY. SPC HAS EXPANDED THE AREA OF GENERAL THUNDER SO HAVE INCLUDED A SLIGHT RISK THROUGH THIS AFTERNOON ACROSS THE ENTIRE AREA. CONSIDERABLE INSTABILITY ALOFT SUGGEST POTENTIAL FOR ISOLATED THUNDER/ASSOCIATED SMALL HAIL WITH VERY STEEP MID LVL LAPSE RATES AND LOW WBZ NEAR 6000 FT. NOT SURE WHAT WILL TRIGGER THE THUNDER EXCEPT SFC CONVERGENCE WITH THE LOW COMING ASHORE AND PERHAPS SOME AFTERNOON SFC HEATING NEAR THE APPROACHING LOW OVER DE. TEMPS MAY BE SEVERAL DEGREES COLDER THAN YDY I95 NWWD. A GUSTY NE WIND FOR A TIME THIS MORNING NEAR 20 MPH EXCEPT GUSTS MIDDAY AND EARLY AFTERNOON MONMOUTH AND OCEAN COUNTIES MAY APPROACH 35 MPH (SEE HRRR GUSTS AS A BAND OF STRONGER WIND WELL NORTH OF THE LOW CENTER SHIFTS WESTWARD WITH LOW ALONG THE S SHORE OF LI).
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&& .SHORT TERM /6 PM THIS EVENING THROUGH 6 AM SATURDAY/... HAVE UNCERTAINTY REGARDING TIMING OF ANY SHOWERS AND ANY LEFTOVER ISOLATED EVENING TSTMS (SE PA/S NJ). CONFIDENCE ON WHAT OCCURS AND WHERE, IS BELOW AVERAGE. IN PART THIS IS DUE TO RECENT LOSS OF CONFIDENCE IN GFS QPF FCSTS. NE WIND DIMINISHING THIS EVENING AND BECOMING LIGHT SOUTHERLY ON THE DELMARVA, POSSIBLY EVEN TO I95. FOG MAY BECOME A PROBLEM TONIGHT WITH A LIGHT WIND IN THE MIDST OF VERTICALLY STACKED MOIST LOW PRESSURE SYSTEM. FCST WAS A 50 50 BLEND OF THE 00Z/6 GFS/NAM MOS. && .LONG TERM /SATURDAY THROUGH THURSDAY/... THE SYNOPTIC SETUP IS COMPRISED OF AN INITIAL CLOSED LOW CENTERED OVER OUR AREA SATURDAY, HOWEVER THIS FEATURE OPENS UP DURING SATURDAY AS IT SHIFTS EASTWARD. THIS OCCURS AS A STRONG SHORT WAVE TROUGH DIVES SOUTHEASTWARD ACROSS THE GREAT LAKES SATURDAY AND INTO THE NORTHEAST SATURDAY NIGHT AND SUNDAY. THE NEW TROUGH AMPLIFIES ACROSS THE NORTHEAST SUNDAY BEFORE GRADUALLY LIFTING OUT MONDAY. A WEAK RIDGE THEN ARRIVES FOR EARLY NEXT WEEK WITH A SURFACE WARM FRONT ALSO MOVING THROUGH. THE WARM FRONT HOWEVER MAY END UP STALLING IN OUR VICINITY WEDNESDAY AND THURSDAY AS ENERGY SHEARS EASTWARD ALONG IT. GIVEN THE PATTERN CHANGE, MUCH WARMER AIR IS EXPECTED TO ARRIVE NEXT WEEK WITH THIS CHANGE STARTING OVER THE WEEKEND ESPECIALLY DURING SUNDAY. THE EXTENT OF THE WARMING THOUGH NEXT WEEK WILL DEPEND ON THE PLACEMENT OF THE FRONTAL BOUNDARY AS IT MAY MEANDER ACROSS OUR CWA AND ALSO PRECIPITATION CHCS. WE USED A MODEL BLEND APPROACH FOR SATURDAY THROUGH SUNDAY NIGHT, THEN BLENDED IN THE 00Z WPC GUIDANCE THEREAFTER. SOME ADJUSTMENTS WERE THEN MADE FOLLOWING ADDITIONAL COLLABORATION WITH OUR NEIGHBORING OFFICES. FOR SATURDAY AND SUNDAY...THIS TIME FRAME BEGINS WITH A CLOSED LOW RIGHT OVER OUR AREA SATURDAY MORNING, HOWEVER THIS FEATURE WILL OPEN UP AND SHIFT EASTWARD DURING THE COURSE OF THE DAY. THIS WILL BE DUE TO A KICKER SHORT WAVE TROUGH AMPLIFYING ACROSS THE GREAT LAKES REGION. A CORE OF -20C TO -24C AIR AT 500 MB IS OVER OUR AREA SATURDAY MORNING, HOWEVER THIS MODIFIES THROUGH THE DAY AS THE TROUGH OPENS UP AND SHIFTS TO OUR EAST. THE PRESENCE OF COLD AIR ALOFT COMBINED WITH SOME LIFT FROM THE CLOSED LOW SHOULD RESULT IN MAINLY SCATTERED SHOWERS SATURDAY ESPECIALLY INLAND. THE FLOW IS LIGHT UNDER THE CLOSED LOW THEREFORE SHOWERS SHOULD BE SLOW MOVERS. SINCE THE AIRMASS IS WARMING DURING THE COURSE OF THE DAY, THIS MAY MITIGATE THE INSTABILITY POTENTIAL. IT APPEARS ANY INSTABILITY IS MARGINAL AND THEREFORE THUNDER WAS NOT ADDED FOR SATURDAY ATTM. AS WE LOSE THE CONTINUOUS ONSHORE FLOW COMPONENT AND THE TROUGH ALOFT WEAKENING THROUGH SATURDAY, THERE SHOULD BE AT LEAST SOME BREAKS OF SUNSHINE. AN AMPLIFYING TROUGH FROM THE GREAT LAKES THEN STARTS TO NEAR OUR AREA TOWARD DAYBREAK SUNDAY. LOW PRESSURE TRACKING TO OUR NORTH WILL PULL A COLD FRONT INTO OUR AREA LATE SATURDAY NIGHT AND THIS FRONT MAY MOVE IN A BIT FASTER. THERE APPEARS TO BE A PLUME OF DEEPER MOISTURE IN COMBINATION WITH FORCING FOR ASCENT TO DRIVE SOME SHOWERS /PERHAPS A BAND OF SHOWERS/ ACROSS MUCH OF OUR AREA. THE STRONGEST FORCING MAY GLANCE OUR NORTHERN AREAS AND THEREFORE THE HIGHEST POPS WERE PLACED THERE LATER AT NIGHT. ANY SHOWERS SHOULD QUICKLY SHIFT OFFSHORE SUNDAY MORNING AS THE COLD FRONT ALSO EXITS, THEN DRIER AIR AND BETTER MIXING WILL PROMOTE SUNSHINE FINALLY RETURNING FOR THE AFTERNOON. IT WILL BE A BIT BREEZY THOUGH SUNDAY IN THE WAKE OF THE COLD FRONT AS LOW-LEVEL LAPSE RATES STEEPEN AND THE PRESSURE GRADIENT TIGHTENS. WE WENT A BIT WARMER THAN MOS FOR SUNDAY ESPECIALLY FOR THE COASTAL PLAIN GIVEN DOWNSLOPING FLOW. HIGH PRESSURE THEN STARTS TO ARRIVE SUNDAY NIGHT ALLOWING THE WINDS TO DIMINISH. FOR MONDAY AND TUESDAY...SOME WEAK RIDGING ARRIVES DURING MONDAY, ALLOWING SURFACE HIGH PRESSURE TO BE OVER OUR CWA TO START BUT IT LOOKS TO SHIFT OFFSHORE LATER MONDAY. THIS WILL ALLOW A SOUTHERLY FLOW TO BECOME BETTER ESTABLISHED AND WITH DOWNSTREAM WAA INCREASING, A WARMER TIME FRAME IS EXPECTED. THE WAA WILL BE USHERED IN VIA A WARM FRONT AS IT CROSSES THE AREA DURING TUESDAY, AND THERE COULD BE ENOUGH LIFT TO PRODUCE SOME SHOWERS OR A THUNDERSTORM MAINLY TUESDAY AFTERNOON AND NIGHT. THE FORECAST CHALLENGE IS THAT THIS FRONT MAY THEN STALL IN OUR AREA AS ENERGY INITIALLY SHEARS EASTWARD ALONG IT. THIS SHEARING ENERGY COULD PRODUCE SOME CONVECTION. FOR WEDNESDAY AND THURSDAY...THE FORECAST CHALLENGE IS WITH THE FRONTAL ZONE AS IT LOOKS TO BE DRAPED ACROSS OUR AREA, HOWEVER A TROUGH AMPLIFYING ACROSS NEW ENGLAND WEDNESDAY MAY PUSH THE FRONT FARTHER SOUTHWARD. THIS SOUTHWARD PUSH COULD BE ENHANCED AS HIGH PRESSURE MAY BUILD DOWN SOME FROM NORTHERN NEW ENGLAND. A TROUGH IN THE MIDWEST HOWEVER PUSHES SURFACE LOW PRESSURE UP THE OHIO VALLEY WEDNESDAY NIGHT INTO THURSDAY, WITH DOWNSTREAM WAA AND SOUTHERLY FLOW ALLOWING THE BOUNDARY TO START LIFTING NORTHWARD SOME AS A WARM FRONT. THIS TIME FRAME SHOULD BE ON THE WARMER SIDE, HOWEVER THIS WILL ULTIMATELY DEPEND ON THE POSITIONING OF THE FRONTAL BOUNDARY AND ANY CONVECTION THAT OCCURS. GIVEN THE UNCERTAINTY, WE BLENDED THE 00Z WPC GUIDANCE IN WITH CONTINUITY AND THEN MADE SOME TWEAKS. && .AVIATION /14Z FRIDAY THROUGH TUESDAY/... THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY AND SURROUNDING AREAS. TODAY...CIGS GENERALLY VARIABLE 600-1600 FT VSBY 1-4 MI IN SHOWERY RAINS DURING THE MORNING WITH POSSIBLE IMPROVING CONDITIONS DURING THE AFTERNOON. ISOLATED TSTM POSSIBLE DURING THE MORNING KACY/KMIV AND THEN DURING THE AFTN ELSEWHERE. TSTMS NOT IN TAF DUE TO LOW CONFIDENCE AND ISOLATED NATURE. NE WIND...GUSTS 15-23 KT FOR A TIME LATER THIS MORNING-MIDDAY. TONIGHT... MVFR/IFR CONDS IN ST/FOG, POSSIBLE CLUSTERS OF SHOWERS. DIMINISHING NE WIND THIS EVENING NEAR AND N OF I78. OTHERWISE LIGHT WIND TRENDING SOUTH. OUTLOOK... SATURDAY...MVFR/IFR CEILINGS IN THE MORNING SHOULD IMPROVE TO VFR IN THE AFTERNOON. MAINLY SCATTERED SHOWERS ARE ANTICIPATED WHICH CAN LOCALLY REDUCE THE VISIBILITY FOR A TIME, THEN A BAND OF SHOWERS ARRIVES LATE AT NIGHT WITH A COLD FRONT. SOUTHEASTERLY WINDS MAINLY LESS THAN 10 KNOTS, BECOMING SOUTHWEST AT NIGHT. SUNDAY...BRIEF MVFR CONDITIONS IN THE MORNING WITH SOME SHOWERS AS A COLD FRONT MOVES THROUGH, OTHERWISE VFR. WEST TO NORTHWEST WINDS INCREASE TO 12-18 KNOTS WITH GUSTS TO 25 KNOTS, THEN DIMINISH AT NIGHT. MONDAY AND TUESDAY...VFR, THEN POSSIBLY SOME MVFR DURING TUESDAY WITH A CHANCE OF SHOWERS AS A WARM FRONT MOVES THROUGH. WESTERLY WINDS AROUND 10 KNOTS MONDAY, BECOMING LIGHT AT NIGHT THEN SHIFTING TO SOUTHERLY TUESDAY. && .MARINE...
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LETTING THE SCA ON THE DELAWARE BAY EXPIRE AS WINDS ARE IN THE MID TEENS AND NOT EXPECTED TO INCREASE MUCH THROUGH THE REST OF THE DAY. SCA CONTINUES OCEAN WATERS THROUGH TONIGHT, ESPECIALLY DUE TO SEAS. SMALL CHANCE WE WILL NEED TO UPGRADE TO A SHORT FUSE SHORT DURATION GALE ANZ450-451 FOR THE PERIOD 16Z-21Z. CONFIDENCE IN UPGRADING WAS LESS THAN 80 PCT SO HAVE HELD OFF FOR NOW. FOG MAY BECOME A MARINE HAZARD LATER THIS FRIDAY NIGHT. OUTLOOK... SATURDAY...THE WINDS ARE ANTICIPATED TO BE LIGHT AS A CLOSED LOW INITIALLY OVERHEAD WEAKENS AND THEN SHIFTS EASTWARD. THE SEAS MAY BE RIGHT AT 5 FEET TO START ESPECIALLY ACROSS THE NORTHERN WATERS BUT OVERALL THE CONDITIONS SHOULD BE TRENDING BELOW ADVISORY CRITERIA. THEREFORE WE DID NOT EXTEND THE ADVISORY ATTM. SUNDAY...WEST TO NORTHWEST WINDS TURN GUSTY TO AROUND 20 KNOTS WITH SEAS AT OR BELOW 4 FEET. IT IS POSSIBLE WINDS GUST TO 25 KNOTS NEARSHORE, HOWEVER OVERALL CONDITIONS ARE ANTICIPATED TO BE BELOW ADVISORY CRITERIA. MONDAY AND TUESDAY...SUB-ADVISORY CONDITIONS ARE ANTICIPATED DESPITE SOME INCREASE IN A SOUTHERLY WIND MONDAY AND THEN AGAIN LATER TUESDAY.
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&& .TIDES/COASTAL FLOODING... PLEASE SEE THE HAZARD CFW STATEMENT FOR THE PARTICULARS RELATING TO EACH AREA. PHL: TIDAL DE ADVY EXPIRED BUT MAY NEED A NEW ONE TO BE ISSUED THIS AFTERNOON FOR THE EARLY SATURDAY MORNING HIGH TIDE CYCLE. CONFIDENCE IN EXCEEDING THE ADVY THRESHOLD WAS NOT QUITE CATEGORICAL ON THIS SHIFT. REEDY POINT UPPER DE BAY, LOWER TIDAL DE LINKED: REISSUED FOR LATE THIS EVENING, SINCE CONFIDENCE IS CATEGORICAL THAT IT WILL REOCCUR, ESPECIALLY BECAUSE THE FUNNELED ENE FLOW THIS MORNING TURNS LIGHT SOUTH THIS EVENING. NJ/DE ATLC COASTS: NO CHANGE IN THE PREVIOUS WARNING. THE TIDAL SURGE IS EXPECTED TO STAY AROUND 1 TO 1.5 FEET TODAY IN THE CONTINUING NORTHEASTERLY FLOW. THE THURSDAY EVENING HIGH TIDE SAW MANY OBSERVING SITES EITHER JUST REACH OR FALL JUST SHY OF MODERATE FLOODING THRESHOLDS. WE ARE FORECASTING MINOR TIDAL FLOODING AROUND THIS MORNING`S HIGH TIDE AND MODERATE FLOODING AROUND THIS FRIDAY EVENING`S HIGH TIDE. RATHER THAN CARRY MULTIPLE HEADLINES, WE CONTINUED WITH THE COASTAL FLOOD WARNING TO COVER BOTH HIGH TIDE CYCLES. MINOR TIDAL FLOODING MAY LINGER WITH THE HIGH TIDE CYCLES ON SATURDAY. && .PHI WATCHES/WARNINGS/ADVISORIES...
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PA...NONE. NJ...COASTAL FLOOD WARNING UNTIL 1 AM EDT SATURDAY FOR NJZ012>014- 020>027. COASTAL FLOOD ADVISORY FROM 10 PM THIS EVENING TO 2 AM EDT SATURDAY FOR NJZ016. DE...COASTAL FLOOD WARNING UNTIL 1 AM EDT SATURDAY FOR DEZ002>004. COASTAL FLOOD ADVISORY FROM 10 PM THIS EVENING TO 2 AM EDT SATURDAY FOR DEZ001. MD...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 6 AM EDT SATURDAY FOR ANZ450>455.
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&& $$ SYNOPSIS...GORSE NEAR TERM...DRAG/MEOLA SHORT TERM...DRAG LONG TERM...GORSE AVIATION...DRAG/GORSE MARINE...DRAG/GORSE/MEOLA TIDES/COASTAL FLOODING...

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