Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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000 FXUS61 KPHI 201636 AFDPHI AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MOUNT HOLLY NJ 1136 AM EST THU NOV 20 2014 .SYNOPSIS... A COLD FRONT WILL MOVE THROUGH THE AREA TODAY. HIGH PRESSURE SYSTEM WILL BUILD INTO THE AREA TONIGHT THROUGH FRIDAY NIGHT. THE HIGH WILL MOVE OFFSHORE THIS WEEKEND. LOW PRESSURE WILL TRACK OVER THE GREAT PLAINS AND UPPER MIDWEST SUNDAY INTO MONDAY. MEANWHILE, A WARM FRONT WILL LIFT NORTHWARD THROUGH THE MID-ATLANTIC STATES SUNDAY NIGHT FOLLOWED BY A COLD FRONT MOVING THROUGH EARLY NEXT WEEK. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... 11:30 AM UPDATE: UPDATING EARLY TO ACCOUNT FOR SLOWER MOVEMENT OF THE FRONTAL BOUNDARY INTO THE REGION. AS A RESULT, TEMPERATURES HAVE BEEN ON THE WARMER END OF WHAT OUR FORECASTING TOOLS SHOW US. RAISED HOURLY AND MAXIMUM TEMPERATURES A FEW DEGREES ACROSS THE REGION PER LAV AND HOURLY OBS. SOUNDINGS ALSO SHOW SOUTHERN DELMARVA LOCATIONS HAVE A SHOT AT MID 50`S FOR HIGHS TODAY. WIND SHIFT TO WESTERLY WITH GUSTS TO 25 MPH IS STILL OCCURRING BUT MAY BE LAGGING BY A HOUR OR TWO FROM PREVIOUS UPDATE. STILL EXPECTING A PRECIPITATION FREE DAY WITH THE DRY AIRMASS CURRENTLY IN PLACE. HOWEVER, ENOUGH MOISTURE IS PRESENT IN THE MID-LEVELS TO RESULT IN A MOSTLY CLOUDY PERIOD TODAY. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 AM FRIDAY/... ANOTHER DRY AND COLD NIGHT EXPECTED ACROSS THE AREA. HIGH PRESSURE WILL BEGIN TO RIDGE IN FROM THE WEST...AND A DECENT PRESSURE GRADIENT WILL STILL BE ACROSS THE AREA. WEST TO NORTHWEST WINDS WILL REMAIN SOMEWHAT GUSTY THIS EVENING AND THEN DECREASE OVERNIGHT. LOW TEMPERATURES WILL FALL INTO THE LOW TO MID 20S ACROSS THE REGION. && .LONG TERM /FRIDAY THROUGH WEDNESDAY/... THE UPPER TROUGH ASSOCIATED WITH THE RECENT COLD STRETCH WILL MOVE DOWNSTREAM OFF THE EAST COAST LATE IN THE WEEK. MEANWHILE, SURFACE HIGH PRESSURE CENTERED OVER THE MIDWEST FRIDAY MORNING WILL BUILD EASTWARD TOWARD THE MID-ATLANTIC REGION FRIDAY AFTERNOON. THE LOW-LEVEL THERMAL TROUGH WILL RESIDE OVERHEAD ON FRIDAY, RESULTING IN THE THIRD WINTER-LIKE DAY THIS WEEK WITH AFTERNOON HIGHS ONLY IN THE 30S. FORECAST 925 MB TEMPS ABOUT 2C WARMER THAN WITH THE RECENT COLD SHOT ON TUESDAY-WEDNESDAY WHICH WOULD TRANSLATE TO HIGHS IN THE MID 30S FOR MOST OF THE AREA (5-10F COLDER IN THE MOUNTAINS). THE FLOW IN THE BOUNDARY LAYER VEERS OUT OF THE NORTHWEST ON FRIDAY, WHICH COULD SHIFT ANY RESIDUAL SNOW SHOWERS FROM LAKE ERIE FARTHER SOUTH TOWARD THE POCONOS. ADDED FLURRIES TO THE FORECAST WITH THE PROSPECTS OF ACCUMULATING SNOW UNLIKELY. THE SETUP FOR RADIATIONAL COOLING WILL BE BETTER FRIDAY NIGHT THAN IN PAST NIGHTS WITH THE CENTER OF THE HIGH OVER THE MID ATLANTIC. FAVORED THE COLDER MOS GUIDANCE FOR TEMPS IN THIS SITUATION. FORECAST MIN TEMPS ARE IN THE MID TO UPPER TEENS IN THE RURAL AREAS AND LOW 20S IN THE URBAN AND COASTAL LOCALES. SURFACE HIGH PRESSURE WILL MOVE OFFSHORE THIS WEEKEND WHILE A RIDGE BUILDS ALOFT OVER THE EASTERN CONUS. THE COLD AIR WILL RETREAT AS SOUTHERLY RETURN FLOW DRAWS WARMER AIR UP THE EASTERN SEABOARD. HIGHS IN THE 30S IN THE HIGHER ELEVATIONS AND 40S IN THE COASTAL PLAIN WILL STILL BE BELOW NORMAL ON SATURDAY. STRENGTHENING SOUTHWESTERLY FLOW ALOFT MAY PRODUCE OVERRUNNING PRECIP IN THE NORTHERN FRINGE OF THE CWA SATURDAY NIGHT. THERE IS SOME CONCERN FOR LIGHT FREEZING RAIN IN THE SHELTERED VALLEYS OF NORTHWEST NJ/NORTHEAST PA WITH LOWS NEAR FREEZING, ALTHOUGH UNCERTAINTY IN THIS HAPPENING IS VERY HIGH. A LARGE SCALE TROUGH WILL AMPLIFY OVER THE CENTRAL CONUS SUNDAY INTO MONDAY, LEAD TO THE DEVELOPMENT OF SURFACE LOW PRESSURE IN THE SOUTHERN PLAINS. THIS SURFACE LOW IS FORECAST TO TRACK NORTHWARD INTO THE UPPER MIDWEST BY MONDAY. DOWNSTREAM IMPACTS OF THIS SYSTEM WILL INCLUDE DEEPENING SOUTHERLY FLOW OVER THE EASTERN CONUS. RAIN IS FORECAST TO OVERSPREAD THE AREA FROM SOUTH TO NORTH SUNDAY AFTERNOON INTO SUNDAY NIGHT AS A WARM FRONT MOVES INTO THE AREA. INCREASED POPS TO 70-80 PERCENT FOR THIS PERIOD WITH THE 00Z GFS/ECMWF/CMC IN GOOD AGREEMENT WITH TIMING OF PRECIP. WE STILL MAY SEE A FEW SHOWERS ON MONDAY BUT POPS WERE LOWERED AS THE DRY SLOT AHEAD OF THE UPSTREAM LOW ADVANCES INTO THE AREA. MONDAY WILL BE THE WARMEST DAY IN THE PERIOD WITH THE POTENTIAL TO SEE HIGHS WELL INTO THE 60S. A COLD FRONT IS FORECAST TO MOVE THROUGH THE REGION SOMETIME EITHER MONDAY NIGHT OR TUESDAY. WITH THE UPPER TROUGH STILL TO OUR WEST AND THE FLOW REMAINING SOUTHWESTERLY ACROSS THE EASTERN SEABOARD, THE CORE OF THE COLD AIR BEHIND THE FRONT SHOULD NOT REACH US BY MIDWEEK. THEREFORE, TEMPS ARE TRENDING TOWARD NORMAL TUESDAY AND SLIGHTLY BELOW NORMAL WEDNESDAY. && .AVIATION /18Z THURSDAY THROUGH TUESDAY/... THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY AND SURROUNDING AREAS. VFR CONDITIONS ARE EXPECTED AT THE TERMINALS TODAY AND TONIGHT. THERE IS SOME MID LEVEL CLOUDINESS WHICH WILL AFFECT THE AREA THIS MORNING. THIS CLOUDINESS IS ASSOCIATED WITH WEAK WARM AIR ADVECTION ACROSS THE AREA. THE CLOUDS WILL EXIT TO THE EAST AS A COLD FRONT CROSSES THE AREA. WINDS...WHICH ARE EITHER VRB OR MOSTLY S/SW OVER THE AREA EARLY THIS MORNING WILL BECOME WRLY AND A BIT GUSTY LATER THIS MORNING AND WILL PERSIST INTO THE AFTERNOON. WINDS GUSTS UP TO 20 KTS POSSIBLE. TONIGHT...VFR WITH MOSTLY CL SKIES AND LIGHT WRLY WINDS. OUTLOOK... FRIDAY...NW WINDS WILL GUST TO 20-25 KT. VFR EXPECTED. FRIDAY NIGHT THROUGH SATURDAY NIGHT...LIGHT SW WINDS DEVELOP. VFR EXPECTED. SUNDAY THROUGH MONDAY...MVFR TO POTENTIALLY IFR POSSIBLE, ESPECIALLY LATE SUNDAY AFTERNOON AND SUNDAY NIGHT AS RAIN MOVES INTO THE AREA. A FEW SHOWERS MAY LINGER INTO MONDAY BUT CONDITIONS SHOULD IMPROVE TO VFR BY THE AFTERNOON. && .MARINE... TOOK THE GALE FLAG DOWN AND RAISED SCA FLAG FOR THE REST OF TODAY AND INTO FRIDAY. NEAR GALE GUSTS POSSIBLE LATER TODAY AFTER THE FROPA AND FRIDAY. UPCOMING SHIFT CAN DECIDE ON FUTURE FLAGS. OUTLOOK... FRIDAY...HIGH-END SCA CONDITIONS LIKELY FRIDAY MORNING BUT WINDS RELAX A BIT DURING THE AFTERNOON. STILL CANNOT RULE OUT THE NEED FOR A GALE WARNING IN THE ATLANTIC WATERS EARLY FRIDAY GIVEN THE DEEP MIXING PROFILES OVER THE OCEAN. FRIDAY NIGHT THROUGH SUNDAY...SUB-SCA CONDITIONS, ALTHOUGH WINDS WILL BE NEAR THRESHOLD FOR A PERIOD SATURDAY NIGHT. SUNDAY NIGHT AND MONDAY...A STRONG SOUTHERLY JET IS FORECAST TO DEVELOP JUST OFF THE SURFACE SUNDAY NIGHT. THIS WILL BE ASSOCIATED WITH A WARM AIRMASS THAT IS MOVING IN, WHICH DOES NOT PROVIDE A FAVORABLE MIXING SETUP. CURRENTLY ADVERTISING SCA WINDS AND SEAS FOR THIS PERIOD. && .PHI WATCHES/WARNINGS/ADVISORIES... PA...NONE. NJ...NONE. DE...NONE. MD...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 6 PM EST FRIDAY FOR ANZ430-431- 450>455. && $$ SYNOPSIS...KLEIN NEAR TERM...GAINES/O`HARA SHORT TERM...O`HARA LONG TERM...KLEIN AVIATION...KLEIN/O`HARA MARINE...KLEIN/O`HARA

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