Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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000 FXUS61 KPHI 300358 AFDPHI AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MOUNT HOLLY NJ 1158 PM EDT SUN MAR 29 2015 .SYNOPSIS...
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A FRONTAL BOUNDARY WILL MOVE THROUGH DURING MONDAY, THEN A FAST MOVING LOW PRESSURE SYSTEM SHOULD SWEEP THROUGH OUR AREA LATE TUESDAY. HIGH PRESSURE BUILDS INTO THE REGION FOR WEDNESDAY, THEN MOVES OFFSHORE ON THURSDAY. THE NEXT COLD FRONT WILL ARRIVE LATE IN THE WEEK.
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&& .NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
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A WEAK COLD FRONT WILL PUSH TOWARD THE REGION OVERNIGHT. NOT MUCH MOISTURE WITH THIS FRONT AND SURFACE DEW POINTS WILL BE SLOW TO INCREASE FOR AWHILE. HOWEVER, THE MODELS ARE INDICATING MEASURABLE PRECIPITATION ESPECIALLY OVER OUR SOUTHERN ZONES TOWARD MORNING. THE 00Z STERLING, VA RAOB SHOWED A RATHER DRY AIRMASS IN PLACE. THIS WILL MOISTEN WITH TIME, HOWEVER THE INITIAL SHOWERS SHOULD EVAPORATE BEFORE REACHING THE GROUND. THEREFORE, CLOUDS WILL BE ON THE INCREASE OVERNIGHT, AND SLIGHT CHC TO CHC POPS WERE BROUGHT IN LATE FROM WEST TO EAST. SOME SHOWERS COULD BE IN THE FORM OF LIGHT SNOW, ESPECIALLY NORTH OF I-78. NO IMPACT IS EXPECTED AND ANY ACCUMULATION WOULD BE MINOR. THE HOURLY GRIDS WERE ADJUSTED BASED ON THE LATEST OBSERVATIONS, WHICH INCLUDED SOME UPWARD ADJUSTMENTS IN TEMPERATURES SO FAR FOR SOME LOCALES. THE TEMPERATURES WERE ADJUSTED DOWN A BIT ESPECIALLY FOR SOME AREAS FOR INTERIOR SOUTHERN AND CENTRAL NEW JERSEY WHERE DECENT RADIATIONAL COOLING IS OCCURRING. THE INCREASING CLOUDS SHOULD EVENTUALLY HALT THE TEMPERATURE FALL. THE PRECIPITATION WORDING WAS CHANGED FROM STRATIFORM TO SHOWERY.
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&& .SHORT TERM /6 AM MONDAY MORNING THROUGH 6 PM MONDAY/... THE FRONT WILL CLEAR THE REGION BY LATE MORNING HELPING TO PULL ANY LINGERING MOISTURE OFF TO OUR EAST...RATHER QUICKLY. DRYING AND WARMING TREND IS EXPECTED FOR MONDAY AS WE MAINTAIN THE SOUTHWEST- WEST SURFACE FLOW. TEMPERATURES SHOULD BE ABLE TO CLIMB BACK TO AVERAGE, IF NOT ABOVE ONCE WE START TO CLEAR SOME OF THE STRATOCU OUT OF THE REGION. WENT WITH THE WARMER MAV GUIDANCE. && .LONG TERM /MONDAY NIGHT THROUGH SUNDAY/... STILL CONSIDERABLE UNCERTAINTY WITH THIS FORECAST ESPECIALLY AS THE SPLIT FLOW PATTERN CONTINUES FOR MUCH OF THE WEEK. TUESDAY AND WEDNESDAY...THE BIG QUESTION THROUGH THIS PERIOD WILL BE THE TRACK OF THE FAST MOVING CLIPPER SYSTEM TUESDAY INTO TUESDAY NIGHT. MOST MODELS BRING THE CENTER OF THE SURFACE LOW ACROSS DELMARVA AND SOUTHERN NJ, WITH THE EXCEPTION OF THE NAM, WHICH TAKES A NORTHERN TRACK, BRINGING THE CENTER OF THE LOW ACROSS NORTHERN NJ. WITH MORE MODEL AGREEMENT ON THE SOUTHERN TRACK, FORECAST FAVORS THE SOUTHERN TRACK, KEEPING HIGHER POPS ACROSS THE SOUTH AND FAVORING THE COLDER GUIDANCE FOR HIGHS ON TUESDAY. BY WEDNESDAY, A SURFACE HIGH MOVES IN FOR A BRIEF APPEARANCE. THURSDAY THROUGH SATURDAY...THIS CONTINUES TO BE THE MOST UNCERTAIN PERIOD OF THE FORECAST. THE GFS AND ECMWF CONTINUE TO SHOW VAST DIFFERENCES IN THE TIMING AND TRACK OF A PAIR OF LOWS. THE FIRST LOW OVER THE HUDSON BAY REGION LATE IN THE WORK WEEK. THE QUESTION WILL BE IF AND WHEN THE ASSOCIATED COLD FRONT WILL TRACK AS FAR SOUTH AS OUR REGION. THE SECOND LOW THE GFS SHOWS DEVELOPING OVER THE SOUTHERN HIGH PLAINS BY THURSDAY NIGHT AND SLIDING EAST JUST SOUTH OF REGION THROUGH SATURDAY, KEEPING A STATIONARY FRONT SOUTH OF US THROUGH THIS TIME. THE ECMWF ON THE OTHER HAND...SHOWS THE LOW FILLING AND ESSENTIALLY DISAPPEARING BY FRIDAY. GIVEN THE UNCERTAINTY, STAYED CLOSE TO THE PREVIOUS FORECAST. HOWEVER, AT THIS POINT, AM CONCERNED THAT THE ECMWF MAY BE UNDERESTIMATING LEE SIDE CYCLOGENESIS. WITH BOTH SOLUTIONS THOUGH, THE END RESULT IS THAT IT WILL BE COOLER (40S AND 50S) FOR THE WEEKEND. && .AVIATION /04Z MONDAY THROUGH FRIDAY/...
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THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY, AND SURROUNDING AREAS. OVERNIGHT...VFR, WITH INCREASING AND GRADUALLY LOWERING CEILINGS. SOUTH-SOUTHWEST WINDS MAINLY LESS THAN 10 KNOTS. SOME SHOWERS WILL BE POSSIBLE TOWARD DAYBREAK, HOWEVER ANYTHING THAT REACHES THE GROUND IS EXPECTED TO BE LIGHT. A QUICK MOVING LOW-LEVEL JET OF 40 KNOTS NEAR 2000 FEET WILL ARRIVE TOWARD MORNING, ESPECIALLY FROM KPHL ON SOUTH AND EAST. MONDAY...MOSTLY VFR. A FRONTAL BOUNDARY WILL CROSS THE REGION DURING THE MORNING WITH A FEW BRIEF RAIN/SNOW SHOWERS. THE COVERAGE DOES NOT LOOKS WIDESPREAD. SOUTHWEST WINDS WILL SHIFT TO THE WEST AND NORTHWEST FROM ABOUT MIDDAY ON, AND INCREASE TO 15 KNOTS WITH GUSTS TO ABOUT 25 KNOTS. OUTLOOK... MONDAY NIGHT...VFR WITH WINDS DIMINISHING. TUESDAY...CEILINGS AND VISIBILITIES DECREASING TO MVFR, POSSIBLY IFR, WITH INCOMING RAIN. SNOW POSSIBLE IN HIGHER TERRAIN. WEDNESDAY...MOSTLY VFR CONDITIONS. THURSDAY AND FRIDAY...MOSTLY VFR, CHANCE FOR RA AND SLIGHT CHANCE FOR TSRA. WITH PRECIPITATION, MVFR CONDITIONS POSSIBLE.
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&& .MARINE... TONIGHT - MONDAY...SUB-SCA EXPECTED ACROSS THE WATERS THROUGH THE LATE EVENING HOURS. THEN WINDS BACK TOWARDS THE SOUTH-SOUTHWEST AND THE SEAS BEGIN TO INCREASE AGAIN. THE PRESSURE GRADIENT TIGHTENS WITH SOME ENHANCED MIXING AND GUSTS CLOSE TO 30 KNOTS RIGHT AROUND A COLD FRONT PASSAGE. WINDS VEER TOWARDS THE WEST-SOUTHWEST BEHIND THE FRONT AND CONTINUE TO GUST FOR A PERIOD. THE GUSTS ON THE BAY AND OCEAN SHOULD DROP BY MONDAY EVENING WHILE THE SEAS REMAIN SOMEWHAT ELEVATED ALONG THE OCEANFRONT. SCA IS GOOD FROM 6Z TONIGHT TO 6Z TUESDAY NIGHT. OUTLOOK... TUESDAY...ONCE WAVES DECREASE BELOW 5 FT EARLY TUESDAY MORNING, WINDS AND SEAS SHOULD REMAIN BELOW SCA CRITERIA FOR THE REST OF THE DAY. TUESDAY NIGHT AND WEDNESDAY...WINDS SHOULD REMAIN BELOW SCA CRITERIA UNLESS THE LOW IS STRONGER THAN FORECAST. SEAS WILL BE DEPENDENT ON THE WIND FORECAST BUT AT THIS POINT ARE GENERALLY EXPECTED TO REMAIN NEAR OR BELOW 5 FT. THURSDAY AND FRIDAY...SOUTHERLY AND SOUTHWESTERLY WINDS WILL LIKELY INCREASE ABOVE 25 KT FOR AT LEAST PART OF THIS PERIOD. SEAS WILL LIKELY INCREASE ABOVE SCA CRITERIA AS WELL. && .PHI WATCHES/WARNINGS/ADVISORIES...
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PA...NONE. NJ...NONE. DE...NONE. MD...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 2 AM EDT TUESDAY FOR ANZ450>455. SMALL CRAFT ADVISORY UNTIL 6 PM EDT MONDAY FOR ANZ430-431.
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&& $$ SYNOPSIS...GORSE/JOHNSON NEAR TERM...GORSE/MIKETTA SHORT TERM...HEAVENER/MIKETTA LONG TERM...JOHNSON AVIATION...GORSE/HEAVENER/JOHNSON MARINE...HEAVENER/JOHNSON

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