Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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000 FXUS61 KPHI 261936 AFDPHI AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MOUNT HOLLY NJ 336 PM EDT SUN APR 26 2015 .SYNOPSIS... A LARGE AND COMPLEX LOW PRESSURE SYSTEM OVER THE WESTERN NORTH ATLANTIC WILL CONTINUE TO MOVE SLOWLY OUT TO SEA DURING THE EARLY AND MIDDLE PARTS OF THE NEW WEEK. MEANWHILE, HIGH PRESSURE WILL BUILD INTO OUR REGION GRADUALLY FROM THE NORTHWEST AND WEST. ANOTHER AREA OF LOW PRESSURE IS FORECAST TO PASS OFF THE NORTH CAROLINA COAST ON THURSDAY BEFORE MOVING OUT TO SEA. HIGH PRESSURE IS EXPECTED TO BUILD INTO OUR REGION FROM THE WEST ON FRIDAY BEFORE PASSING OFF THE COAST DURING THE COMING WEEKEND. && .NEAR TERM /UNTIL 6 AM MONDAY MORNING/... FOR TONIGHT...HIGH PRES SHOULD CONT TO BUILD SWD INTO THE N-CNTRL US AND SLIGHTLY EWD INTO THE MID-ATLANTIC REGION. MEANWHILE LOW PRES IS FCST TO RETRO-GRADE SWWD OVER NOVA SCOTIA IN ASSOCN WITH AN UPPER TROF SWINGING SWD FROM SERN CANADA INTO THE NERN US. THE RESULT WILL BE AN INCRG E-W PRES GRADIENT OVER OUR AREA WHICH SHOULD BE ABLE TO MAINTAIN A LIGHT N-NNW FLOW OVERNIGHT SKIES WILL BE MOSTLY CLEAR BUT SOME CLOUDINESS IS POSSIBLE AHEAD OF THE UPPER TROF. OVERNIGHT MINS SHOULD BE SLIGHTLY WARMER THAN LAST NIGHT...BUT SOME MID-30S ARE POSSIBLE IN SOME BETTER- RADIATING AREAS. WILL INCLUDE MENTION OF PATCHY FROST BUT EXTENT DOES NOT SEEM WIDE ENOUGH TO JUSTIFY ANOTHER ADVISORY. && .SHORT TERM /6 AM MONDAY MORNING THROUGH 6 PM MONDAY/... FOR MONDAY THE SURFACE PATTERN WILL BE SIMILAR TO TODAY WITH HIGH PRES OVER THE MID-WEST AND LOW PRES WELL OFF THE EAST COAST WITH A CENTER NEAR NOVA SCOTIA. NORTH WINDS WILL CONTINUE BUT SHOULD BE SMWHAT STRONGER THAN TODAY WITH A STRONGER GRADIENT BETWEEN THE HIGH AND LOW. MAX TEMPS MONDAY AFTN COULD BE A LITTLE COOLER THAN TODAY DUE TO INCREASED CLOUDINESS...ESPECIALLY FROM PHL NORTH. THERE WILL BE A CHANCE OF SHOWERS ON MONDAY...ESPECIALLY IN THE AFTN...AS AN UPPER-LEVEL HGT/THERMAL TROF ROTATES SWD ACROSS THE AREA. COOLER TEMPS ALOFT WILL RESULT IN INCREASED INSTBY ALONG WITH MID-LEVEL MOISTURE...HOWEVER THE LOW LEVELS OF THE ATMOS WILL REMAIN RATHER DRY WITH INVERTED VEE TYPE SOUNDING. THUS THE PRECIP FROM SHOWERS THAT DEVELOP WILL TEND TO EVAPORATE BEFORE REACHING THE GROUND. WE HAVE INCLUDED SLGT CHC POPS FOR MOST OF OUR FCST AREA WITH SLGTLY HIER CHC POPS WELL N/W OF PHL. && .LONG TERM /MONDAY NIGHT THROUGH SUNDAY/... WE SHOULD REMAIN UNDER THE INFLUENCE OF A MID LEVEL LOW OFF NOVA SCOTIA DURING THE PERIOD FROM MONDAY NIGHT INTO TUESDAY NIGHT. SOME CLEARING IS EXPECTED DURING THE COURSE OF MONDAY NIGHT WITH CUMULUS ANTICIPATED TO DEVELOP ON TUESDAY DUE TO DAYTIME HEATING. A NORTH TO NORTHWEST WIND AROUND 10 TO 15 MPH IS FORECAST FOR MONDAY NIGHT INTO TUESDAY MORNING. WIND SPEEDS ARE EXPECTED TO DIMINISH A BIT FOR TUESDAY AFTERNOON AS THE SURFACE PRESSURE GRADIENT IN OUR REGION RELAXES. A WEAK MID LEVEL RIDGE IS FORECAST TO APPROACH FROM THE WEST AND NORTHWEST AND IT SHOULD BE OVERHEAD ON WEDNESDAY AND WEDNESDAY NIGHT. THE MODELS CONTINUE TO COME INTO BETTER AGREEMENT WITH THEIR HANDLING OF THE DEVELOPING MID LEVEL TROUGH OVER THE EASTERN STATES FOR THURSDAY AND FRIDAY. ALSO, THERE IS IMPROVING BUT NOT YET IDEAL CONSENSUS REGARDING THE SURFACE LOW. WE WILL CONTINUE TO FAVOR THE ECMWF SOLUTION BASED ON ITS BETTER RUN TO RUN CONSISTENCY. THE SURFACE LOW SHOULD BE OFF CAPE HATTERAS ON THURSDAY AFTERNOON BEFORE MOVING NORTHEASTWARD AND OUT TO SEA. OUR REGION IS ANTICIPATED TO STAY ON THE NORTHWESTERN FRINGE OF ITS MAIN IMPACTS. THE EXACT TRACK OF THE LOW REMAINS UNCERTAIN SO WE MAY OR MAY NOT GET SOME RAIN IN ADDITION TO THE CLOUD COVER, ESPECIALLY ON THE COASTAL PLAIN. WE HAVE KEPT THE 30 PERCENT CHANCE OF SHOWERS FOR THE TIME BEING. AN EAST WIND AROUND 10 MPH ON THURSDAY IS EXPECTED TO INCREASE TO 10 TO 15 MPH ON THURSDAY NIGHT AS IT BACKS TO THE NORTHEAST, THEN TO THE NORTH. THE COMPLEX MID LEVEL TROUGH IS FORECAST TO MOVE OUT OVER THE WESTERN NORTH ATLANTIC FOR THE WEEKEND. A MID LEVEL SHORT WAVE IS EXPECTED TO DROP DOWN FROM THE NORTHWEST AT THAT TIME. THE FEATURE IS ANTICIPATED TO HAVE LIMITED MOISTURE ASSOCIATED WITH IT. A SUBSTANTIAL RIDGE FROM THE WEST IS FORECAST TO BUILD OVER THE EASTERN STATES FOR THE FIRST FULL WEEK OF MAY. TEMPERATURES SHOULD NOT BE FAR FROM NORMAL DURING THE PERIOD FROM TUESDAY THROUGH SUNDAY. && .AVIATION /20Z SUNDAY THROUGH FRIDAY/... THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY AND SURROUNDING AREAS. VFR CONDS ARE EXPECTED TO PREVAIL AT ALL OUR TAF SITES FOR THE NEXT 24 HOURS OR SO. AFTN STRATO-CU HAVE DEVELOPED OVER MUCH OF THE AREA BUT BASES ARE HIGH...WELL ABOVE BKN050. THESE CLOUDS WILL TEND TO DISSIPATE DURING THE EVENING BUT MAY LINGER A WHILE AFTER SUNSET... ESPECIALLY AROUND RDG/ABE/TTN. A WEAK SFC TROF OVER THE AREA IS RESULTING IN LIGHT WINDS OVER THE AREA THIS AFTERNOON. WINDS SHOULD REMAIN LIGHT TONIGHT BUT WITH A PREVAILING NW DIRECTION GRADUALLY DEVELOPING. FOR MONDAY...A STRONGER SFC PRES GRADIENT IS EXPECTED TO DEVELOP WITH WILL RESULT IN STRONGER NW WINDS. SOME GUSTS TO AROUND 20KT ARE LIKELY DURG THE AFTN. CONSIDERABLE CLOUDINESS WILL DEVELOP BUT AGAIN THE CLOUD BASES SHOULD BE 5K FT OR HIGHER. SOME CLOUDS WILL BUILD UP HIGH ENOUGH TO PRODUCE SHOWERS BUT MUCH OF THE RAIN IS LIKELY TO EVAPORATE BEFORE REACHING THE GROUND...THUS LITTLE IF ANY LIMITS TO VSBY ARE EXPECTED. OUTLOOK... MONDAY NIGHT THROUGH WEDNESDAY NIGHT...MAINLY VFR. THURSDAY AND THURSDAY NIGHT...MAINLY VFR WITH A CHANCE OF SHOWERS. AN EAST TO NORTHEAST WIND AROUND 10 KNOTS IS EXPECTED ALONG WITH ITS POTENTIAL IMPACT ON OPERATIONS AT KPHL. FRIDAY...MAINLY VFR. && .MARINE... WINDS AND SEAS ARE CURRENTLY RATHER QUIET OVER THE FCST WATERS AND SHOULD REMAIN SO FOR TONIGHT AND MUCH OF THE DAY TOMORROW. HWVR...FOR MONDAY AFTN WINDS WILL INCREASE FROM THE NW AND SEAS WILL BEGIN TO BUILD. CONDS ARE EXPECTED TO REMAIN BELOW SCA CRITERIA DURING THE DAY BUT WILL CONTINUE TO DETERIORATE INTO MONDAY EVENING WHEN A SCA WILL GO INTO EFFECT. OUTLOOK... MONDAY NIGHT AND TUESDAY MORNING...A SMALL CRAFT ADVISORY IS IN EFFECT FOR A NORTHWEST TO NORTH WIND GUSTING TO 25 OR 30 KNOTS. TUESDAY AFTERNOON THROUGH THURSDAY MORNING...NO MARINE HEADLINES ARE ANTICIPATED. THURSDAY AFTERNOON THROUGH FRIDAY...A SMALL CRAFT ADVISORY MAY BE NEEDED FOR WIND GUSTS OF 25 TO 30 KNOTS AND FOR WAVES ON OUR OCEAN WATERS IN EXCESS OF 5 FEET. THE WIND DIRECTION IS ANTICIPATED TO BACK GRADUALLY FROM THE EAST TO THE NORTH. THERE IS THE POTENTIAL FOR GALE FORCE GUSTS IF LOW PRESSURE OVER THE OCEAN TRACKS CLOSER TO THE COAST THAN CURRENTLY EXPECTED. && .FIRE WEATHER... WIND GUSTS AROUND 20 MPH ARE EXPECTED FOR TUESDAY MORNING WITH GUSTS FORECAST TO DROP INTO THE 10 TO 15 MPH RANGE DURING THE AFTERNOON. RELATIVE HUMIDITY VALUES ARE ANTICIPATED TO DROP AROUND 30 PERCENT IN MUCH OF OUR REGION ON TUESDAY AFTERNOON. PRESENTLY, IT DOES NOT APPEAR AS THOUGH BOTH ELEMENTS WILL COME TOGETHER TO CREATE AN ENHANCED CONCERN FOR WILDFIRE SPREAD. HOWEVER, CONDITIONS MAY GET CLOSE. && .PHI WATCHES/WARNINGS/ADVISORIES... PA...NONE. NJ...NONE. DE...NONE. MD...NONE. MARINE...SMALL CRAFT ADVISORY FROM 8 PM MONDAY TO NOON EDT TUESDAY FOR ANZ430-431-450>455. && $$ SYNOPSIS...IOVINO NEAR TERM...AMC SHORT TERM...AMC LONG TERM...IOVINO AVIATION...AMC/IOVINO MARINE...AMC/IOVINO FIRE WEATHER...IOVINO

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