Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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000 FXUS61 KPHI 190502 AFDPHI AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MOUNT HOLLY NJ 102 AM EDT SUN OCT 19 2014 .SYNOPSIS... HIGH PRESSURE WILL BUILD ACROSS THE MID-ATLANTIC STATES SUNDAY NIGHT AND MOVE OFFSHORE ON MONDAY. BY TUESDAY A COLD FRONTAL BOUNDARY WITH AN AREA OF LOW PRESSURE WILL DIVE SOUTHEAST FROM THE GREAT LAKES INTO THE MID-ATLANTIC STATES. ANOTHER LOW PRESSURE WILL FORM OFF THE CAROLINA COASTLINE. THESE TWO LOW PRESSURE SYSTEMS WILL INTERACT WITH EACH OTHER AND MERGE JUST OFFSHORE WEDNESDAY AND THURSDAY, DEPARTING THE REGION BY FRIDAY. && .NEAR TERM /UNTIL 6 AM THIS MORNING/... A PAIR OF SHORT WAVES PREDICTED TO PASS OVERNIGHT ARE INDICATING AT LEAST A CHANCE OF PCPN REACHING THE GROUND IN THE NWRN PART OF OUR CWA. SO WE EXTENDED THE MENTION OF SHOWERS LONGER. WE SUPPOSE HIGHEST TERRAIN NORTHWEST MIGHT SEE A WET SNOWFLAKE TOWARD DAWN. NO OTHER BIG CHANGES TO THE ESTF, MAINLY SOME SKY COVER ADJUSTMENTS IN THE FIRST COUPLE OF HOURS SOUTH. WE GENERALLY EXPECT PARTLY TO MOSTLY CLOUDY SKIES FOR THE OVERNIGHT PERIOD. A STEADY BREEZE IS EXPECTED TO CONTINUE THROUGH THE NIGHT. THIS WILL KEEP THE BOUNDARY LAYER WELL MIXED, SO EVEN WITH THE COOLER DEWPOINTS AND AIRMASS IN PLACE, TEMPERATURES WILL ONLY BE ABLE TO DROP INTO THE LOW TO MID- 40S. && .SHORT TERM /6 AM THIS MORNING THROUGH 6 PM MONDAY/... SECONDARY COLD FRONT CONTINUES TO PUSH THROUGH TOMORROW LATE MORNING AND WE SEE ANOTHER BOUT OF STRONGER NORTHWEST WIND GUSTS WITH MUCH BETTER COLD AIR ADVECTION TAKING PLACE. THE FRONTAL PASSAGE, WITH NOT MUCH MOISTURE TO WORK WITH, SHOULD BE DRY AS IT PUSHES THROUGH BUT THE AIRMASS WILL BE NEARLY 10-15 DEGREES COLDER THAN TODAY`S. HIGHS WILL END UP BEING IN THE LOW TO MID-50S. && .LONG TERM /MONDAY NIGHT THROUGH SATURDAY/... SUNDAY NIGHT: HIGH PRESSURE WILL BE LOCATED TO OUR SOUTH. THIS WILL RESULT IN CLEAR SKIES AND LIGHT WINDS, GOOD SET-UP FOR RADIATIONAL COOLING. DEWPOINTS BY BOTH THE ECMWF AND GFS IN THIS PERIOD ARE MODELED IN THE MID TO UPPER 20`S. CURRENT THINKING IS THE GFS AND THE RESPECTIVE MAV GUIDANCE ARE TO AGGRESSIVE WITH COOLER LOW TEMPERATURES. EVEN WITH THAT THE MET GUIDANCE HAS LOWS RIGHT AROUND FREEZING ACROSS THE NORTHWEST PORTION OF THE CWA. MODERATE CONFIDENCE IS CURRENTLY PRESENT FOR A FREEZE EVENT ACROSS CARBON, MONROE AND SUSSEX COUNTIES SO A FREEZE WATCH HAS BEEN ISSUED. MONDAY AND MONDAY NIGHT: STILL LOOKS LIKE A NICE DAY AS HIGH PRESSURE MOVES OFFSHORE, LIGHT WINDS BECOMING SOUTHWEST. CLOUDS BEGIN TO INCREASES MONDAY NIGHT AHEAD OF THE NEXT COLD FRONTAL SYSTEM TO IMPACT THE REGION KEEPING TEMPERATURES UP. FAIRLY LIMITED TEMPERATURE SPREAD AMONG THE VARIOUS TEMPERATURE FORECASTING TOOLS WITH HIGHS AROUND 60 FOR MOST OF THE AREA, COOLER NW. TUESDAY THROUGH THURSDAY NIGHT: A COASTAL LOW PRESSURE SYSTEM WILL DEVELOP OFFSHORE AND BE SLOW TO MOVE NORTHEAST THROUGHOUT THIS PERIOD. THE END RESULT WILL BE GRAY GLOOMY COOLER DAYS FEATURING RAIN SHOWERS AND SOME NORTHWESTERLY WINDS BY THE END OF THIS PERIOD. THE FORMATION OF THIS LOW PRESSURE WILL START WITH TWO PIECES, A STRONG UPPER LEVEL LOW AND COLD FRONT DIVING FROM THE GREAT LAKES INTO THE MID-ATLANTIC AND A LOW PRESSURE FORMING OFF THE CAROLINAS. THE UPPER LOW AND COLD FRONTAL BOUNDARY WILL BEGIN TO BRING SOME SCATTERED SHOWERS ON TUESDAY TO THE REGION WITH A MOISTURE PLUME FROM THE CAROLINA LOW WELL OFFSHORE. BY TUESDAY NIGHT WE BEGIN TO SEE MORE INTERACTION BETWEEN THE FEATURES, PHASING. THE MAIN LOW FORMS OFF THE SOUTHERN NEW ENGLAND COASTLINE BY WEDNESDAY WITH THE MAJORITY OF ATLANTIC MOISTURE BROUGHT INTO SOUTHERN NEW ENGLAND. TO COMPARE OUR REGION WOULD BE FAVORED FOR JUST SOME WRAP AROUND SHOWERS. THE LAST TWO ECMWF RUNS SHOW AN INTERESTING INVERTED TROUGH FEATURE WHICH ENHANCES SOME OF THE SHOWER ACTIVITY. ON THE OTHER HAND THE OPERATIONAL GFS AND CMC KEPT A GOOD PORTION OF THE AREA DRY THROUGHOUT MOST OF THIS PERIOD. IN TERMS OF THE ENSEMBLES SEVERAL WETTER MEMBERS WERE PRESENT IN THE 06Z GEFS WHILE THE 00Z ECMWF SEEMED TO BE A LITTLE FURTHER SOUTHEAST COMPARED TO IT`S ENSEMBLE MEAN. THE NAO IS LIKELY TO BE NEAR NEUTRAL, WHICH DOESN`T INSPIRE CONFIDENCE THAT THE SYSTEM WILL STAY CLOSER TO THE COASTLINE THAN CURRENTLY MODELED. CONFIDENCE IS INCREASING SOMEWHAT THAT THIS PERIOD WILL BE DOMINATED BY SOME SCATTERED SHOWERS STARTING TUESDAY AND LASTING THROUGH THURSDAY WITH AREAS FURTHER NORTHEAST CLOSER TO THE LOW STANDING THE BEST CHANCE TO SEE A MORE WIDESPREAD RAINFALL. WITH PLENTY OF CLOUDS, LOW TEMPERATURES WILL STAY UP AT NIGHT CLOSE TO 50 FOR MOST OF US WHILE HIGHS STRUGGLE INTO THE LOW 60`S, COOLER NW. NOT MUCH SPREAD IN THE MODELS AND THERE ENSEMBLES/ STATISTICAL GUIDANCE ON TEMPERATURES. IN TERMS OF TIDES ONCE A BETTER HANDLE OF THE LOW PRESSURE POSITION AND WIND DIRECTION ARE ESTABLISHED CONFIDENCE WILL INCREASE ON WHAT IF ANY TIDAL ISSUES WILL BE PRESENT. FRIDAY THROUGH SATURDAY: LOW PRESSURE SYSTEM FINALLY DEPARTS WITH HIGH PRESSURE BUILDING BACK IN AT THE VERY END OF THE PERIOD. WENT ON THE WARMER END OF THE MODEL SUITE FOR HIGH TEMPERATURES ON SATURDAY CLOSER TO MEX GUIDANCE GIVEN REBOUNDING 925/850 MB TEMPS. && .AVIATION /06Z SUNDAY THROUGH THURSDAY/... THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY AND SURROUNDING AREAS. 06Z TAFS VFR. REST OF THE NIGHT...MAINLY A MID DECK VFR CIG FCST WITH WEST WINDS CLOSE TO 10 KTS. HIGHER TERRAIN AIRPORTS WILL SEE SOME MVFR CIGS. SUNDAY DAY...VFR CIGS POSSIBLE AT AIRPORTS MAINLY TO THE NORTH OF PHILADELPHIA AND INTERSTATE 195 IN NJ. EVEN SOME MVFR CIGS EARLY IN THE HIGHER TERRAIN. ELSEWHERE MAINLY JUST A SCATTERED DECK OF CU CLOUDS AFTER 12Z OR 13Z. NORTHWEST WINDS WILL AVERAGE AROUND 15 KNOTS WITH GUSTINESS TO AROUND 25 KNOTS. STAT GUIDANCE IS SUGGESTING THE PEAK WINDS SHOULD OCCUR BY ABOUT 18Z. CLEARING OR CLEAR SKIES AND DIMINISHING WINDS TOWARD SUNSET. SUNDAY NIGHT...VFR WITH LIGHTER NORTHWEST TO WEST WINDS BECOMING LIGHT AND VARIABLE AT MOST TERMINALS. ANY CLOUDS WILL BE AT CIRRUS LEVEL AND MORE LIKELY LATER AT NIGHT. OUTLOOK... MONDAY THROUGH MONDAY NIGHT...VFR. TUESDAY...SOME RESTRICTIONS TO MVFR WITH SCATTERED SHOWERS. TUESDAY NIGHT THROUGH THURSDAY... MAINLY MVFR CONDITIONS WITH SCATTERED SHOWERS. NORTH TO NORTHWEST WINDS WEDNESDAY AFTERNOON THROUGH THURSDAY FROM 10-15 KNOTS WITH HIGHER GUSTS. && .MARINE... TONIGHT - SUNDAY...SCA CONDITIONS PERSIST ACROSS ALL OUR WATERS THROUGH LATE SUNDAY NIGHT. GUSTY NORTHWEST WINDS, AROUND 25 TO 30 KNOTS, WILL CONTINUE...AT THE MOUTH OF THE BAY WE COULD SEE CLOSE TO GALE FORCE GUSTS WITH THE POTENTIAL WIND FUNNELING. SEAS WILL REMAIN ELEVATED AROUND 4 TO 7 FEET ON THE OCEANFRONT. OUTLOOK... SUNDAY NIGHT: EARLY IN THE EVENING SEAS ARE STILL LIKELY TO BE AROUND FIVE FEET WITH SOME HIGHER GUSTS AROUND 25 KNOTS FROM THE NORTHWEST. THESE VALUES WILL BE DECREASING BELOW SCA THRESHOLD EARLY AND WILL ALLOW THE SCA TO EXPIRE EARLY SUNDAY EVENING. MONDAY THROUGH WEDNESDAY MORNING: SEAS AND WINDS BELOW SCA CRITERIA BUT INCREASING WEDNESDAY MORNING WITH THE DEVELOPMENT OF A LOW PRESSURE TO OUR NORTHEAST. WEDNESDAY AFTERNOON THROUGH THURSDAY: OVERALL THINKING IS THAT WAVEWATCH IS UNDERDONE. SEAS WILL LIKELY OR OVER FIVE FEET THROUGH MOST OF THIS PERIOD. NORTHWEST WIND GUSTS OVER 25 KNOTS ARE ALSO POSSIBLE. && .PHI WATCHES/WARNINGS/ADVISORIES... PA...FREEZE WATCH FROM LATE TONIGHT THROUGH MONDAY MORNING FOR PAZ054-055. NJ...FREEZE WATCH FROM LATE TONIGHT THROUGH MONDAY MORNING FOR NJZ001. DE...NONE. MD...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL MIDNIGHT EDT TONIGHT FOR ANZ450>455. SMALL CRAFT ADVISORY UNTIL 6 PM EDT THIS EVENING FOR ANZ430- 431. && $$ SYNOPSIS...GAINES NEAR TERM...GIGI/HEAVENER/ROBERTSON SHORT TERM...HEAVENER LONG TERM...GAINES AVIATION...GAINES/GIGI MARINE...GAINES/HEAVENER

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