Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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000 FXUS61 KPHI 201945 AFDPHI AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MOUNT HOLLY NJ 245 PM EST THU NOV 20 2014 .SYNOPSIS... A COLD FRONT WILL CROSS THE WATERS LATER TODAY. A STRONG HIGH PRESSURE SYSTEM WILL MOVE IN FROM THE WEST ON FRIDAY, CRESTING OVER THE REGION ON SATURDAY BEFORE MOVING OFFSHORE ON SUNDAY. MEANWHILE, LOW PRESSURE WILL DEVELOP ACROSS THE INTER-MOUNTAIN WEST, AND TRACK NORTHEASTWARD TO LAKE MICHIGAN. THIS LOW WILL BRING A COLD FRONT THROUGH THE REGION EARLY NEXT WEEK. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... THE COLD FRONT IS MOVING SLOWLY TOWARDS THE REGION AND WILL MOVE THROUGH THE AREA LATER TODAY. DUE TO THE SLOWER MOVEMENT OF THE FRONT, WARMER AIR HAS MADE ITS WAY INTO THE AREA ON THE SOUTHWESTERLY FLOW. TEMPERATURES WERE ADJUSTED TO BETTER REFLECT CURRENT OBSERVATIONS AND TRENDS. SHOULD SEE MAX TEMPS INTO THE MID 50S ACROSS SOUTHERN DELMARVA AND EXTREME SOUTHERN NEW JERSEY, RANGING TO THE LOWER 40S ACROSS THE NORTHERN PARTS OF THE FORECAST AREA. THE SOUTHERN POCONOS AND THE AREAS OF HIGHER TERRAIN WILL REMAIN COOLER, IN THE MID 30S TO NEAR 40. WINDS WILL GRADUALLY SHIFT TO A MORE WESTERLY DIRECTION BUT WILL REMAIN GUSTY THROUGH THIS AFTERNOON AND INTO THIS EVENING. SKIES HAVE LARGELY CLEARED OUT AND SHOULD BE MOSTLY TO PARTLY SUNNY THROUGH THE REST OF THE AFTERNOON. && .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 /20Z THURSDAY THROUGH TUESDAY/...
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THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY AND SURROUNDING AREAS. AREAS OF MID TO HIGH LEVEL CLOUDS AT 5-10,000 FEET HAVE BECOME MORE SCATTERED THIS AFTERNOON. ONLY SCATTERED MID-LEVEL CLOUDS ARE EXPECTED THROUGH FRIDAY. HOWEVER, THE MAIN STORY WILL BE GUSTY WINDS. SPORADIC GUSTS AROUND 25 KNOTS HAVE OCCURRED THIS AFTERNOON AND WILL CONTINUE GUSTS IN THE TAFS THROUGH 22Z. THE ENVIRONMENT IS FAVORABLE AGAIN FRIDAY FOR AFTERNOON WIND GUSTS AROUND 25 KNOTS. THE WIND DIRECTION WILL BE MORE NORTH OF WEST AROUND 300 COMPARED TO THE SOUTH FO WEST TODAY AROUND 250/260. OUTLOOK... 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.
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&& .MARINE... SMALL CRAFT ADVISORY IN EFFECT THROUGH FRIDAY. NEAR GALE GUSTS POSSIBLE LATER TODAY AFTER THE FROPA AND FRIDAY. 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...MEOLA SHORT TERM...O`HARA LONG TERM...KLEIN AVIATION...GAINES/KLEIN/O`HARA MARINE...KLEIN/O`HARA

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