Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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000 FXUS61 KPHI 300930 AFDPHI AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MOUNT HOLLY NJ 430 AM EST FRI JAN 30 2015 .SYNOPSIS... LOW PRESSURE WILL MOVE OUT OVER THE NEW ENGLAND WATERS TODAY AND A COLD FRONT WILL CROSS THE AREA THIS MORNING. MUCH COLDER AND WINDY CONDITIONS WILL ARRIVE BEHIND THE FRONT. HIGH PRESSURE WILL BUILD ACROSS THE AREA FOR TONIGHT THROUGH EARLY SUNDAY. A LOW PRESSURE SYSTEM WILL AFFECT THE AREA SUNDAY NIGHT THROUGH MONDAY. ANOTHER HIGH WILL MOVE IN FOR TUESDAY AND WEDNESDAY. A COASTAL DISTURBANCE MAY AFFECT THE AREA NEXT THURSDAY. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... 08Z SURFACE ANALYSIS SHOWS AN AREA OF LOW PRESSURE LOCATED JUST NORTHEAST OF LAKE ONTARIO. A COLD FRONT EXTENDS SOUTHWARD FROM THE LOW DOWN THE LEE SIDE OF THE APPALACHIANS. A STRONGER ARCTIC COLD FRONT WAS POSITIONED OVER THE MIDWEST. THREE AREAS OF PRECIP WERE NOTED ON THE REGIONAL MOSAIC RADAR AT 430 AM, EACH ASSOCIATED WITH SEPARATE MID-LEVEL SHORTWAVE TROUGHS. THERE WAS VERY LIGHT SNOW AND FLURRIES THAT HAS LINGERED ALONG AND NORTH OF I-80 FOR MUCH OF THE NIGHT. THE SECOND AREA TO NOTE WAS A BAND OF RAIN/SNOW SHOWERS THAT HAS STARTED TO DEVELOP OVER THE PAST HOUR OR SO TO THE EAST OF I-95. HIRES MODELS HAVE THIS AREA OF PRECIP SHIELD BLOSSOMING EARLY THIS MORNING. ADDITIONALLY THERE WAS AN AREA OF SNOW BACK TO THE WEST OVER STATE COLLEGE AND PITTSBURGH. THEREFORE, EXPECT PERIODS OF SNOW (MIXING WITH RAIN TOWARD THE COAST) THROUGH A GOOD PART OF THE MORNING. MOST LOCATIONS WILL NOT PICK UP MUCH MORE THAN A HALF INCH OF SNOWFALL (AND NOT EVERYONE WILL SEE MEASURABLE SNOW). THE POCONOS AND FAR NORTHWEST NJ MAY GET AN ADDITIONAL INCH WITH THIS ACTIVITY WHERE THE SNOW WILL BE THE MOST PERSISTENT DURING THE MORNING. THE OTHER STORY TODAY WILL BE THE GUSTY NORTHWEST WINDS THAT DEVELOP BEHIND THE FIRST COLD FRONT THIS AFTERNOON. WIND GUSTS UP TO 35 MPH ARE EXPECTED THROUGH EARLY THIS AFTERNOON. A SECOND COLD FRONT WILL MOVE THRU THE AREA LATE IN THE DAY, MARKING THE ARRIVAL OF ARCTIC AIR. WINDS WILL STRENGTHEN FURTHER BEHIND THIS FRONT AS LAPSE RATES BECOME VERY STEEP AND THE PRESSURE GRADIENT TIGHTENS. A WIND ADVISORY WAS ISSUED FOR THE ENTIRE FORECAST AREA STARTING AT 4 PM TODAY. THE HIGHER ELEVATIONS IN EASTERN PA AND NORTHWEST NJ ARE MOST LIKELY TO GET WIND GUSTS NEAR 45 MPH INITIALLY. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 AM SATURDAY/... LOW PRESSURE WILL RAPIDLY DEEPENS OFF THE NEW ENGLAND COAST THIS EVENING. MEANWHILE, HIGH PRESSURE OVER THE MIDWEST WILL BUILD EASTWARD. A TIGHTENING PRESSURE GRADIENT BETWEEN THESE TWO SYSTEMS WILL PRODUCE WINDY CONDITIONS ACROSS THE MID ATLANTIC. AS MENTIONED IN THE NEAR TERM, A WINDY ADVISORY WAS ISSUED FOR THE ENTIRE AREA AND GOES THROUGH TONIGHT. MOMENTUM TRANSFER ALGORITHMS ON GFS BUFKIT SOUNDINGS SUPPORT MIXING OF 40 KT WINDS DOWN TO THE SURFACE WHILE THE WIND PROFILE FROM THE NAM ARE SLIGHTLY WEAKER. VERY STEEP LAPSE RATES WILL BE PRESENT IN THE BOUNDARY LAYER UNDER STRONG CAA AS THE ARCTIC AIRMASS MOVES IN. THE DEEPER MIXING ADVERTISED BY THE GFS AND SEVERAL SREF MEMBERS WAS FAVORED IN THIS SETUP, WHICH SUPPORTED A WIND ADVISORY. LOW TEMPS TONIGHT RANGE FROM NEAR ZERO IN THE POCONOS TO MID TEENS IN THE DELMARVA. COMBINED WITH THE WINDS, WIND CHILLS ARE FORECAST TO BE AT OR BELOW ZERO ACROSS JUST ABOUT THE ENTIRE AREA BY EARLY SATURDAY MORNING. THE WIND CHILL ADVISORY THAT WAS ALREADY IN EFFECT FOR THE POCONOS WAS EXPANDED TO SUSSEX COUNTY, NJ FOR WIND CHILL VALUES OF -10F TO -20F. && .LONG TERM /SATURDAY THROUGH THURSDAY/... SATURDAY THRU SUNDAY AFTERNOON... HIGH PRESSURE TO THE WEST WILL CONTINUE TO USHER COLD AND WINDY CONDITIONS SATURDAY WITH TEMPERATURES SOME 20 DEGREES BELOW NORMAL. WIND ADVISORIES WILL BE IN EFFECT FOR THE CWA FOR THE MORNING SATURDAY. WINDS WILL SUBSIDE BY LATE IN THE DAY SAT AS THE HIGH CRESTS OVER THE AREA. DRY WEATHER IS FORECAST THROUGH SUNDAY MORNING. SKY COVER...PARTLY TO MOSTLY SUNNY SAT AND MOSTLY CLOUDY SKIES SUNDAY. SUNDAY EVENING THROUGH MONDAY... THE NEXT SIGNIFICANT WEATHER PRODUCER FOR OUR AREA WILL ARRIVE FROM THE OHIO VALLEY SUNDAY AND THE CENTER OF THE LOW WILL MOVE ACROSS THE DELMARVA MONDAY MORNING. THE MOST RECENT MODELS ARE OFFERING A MORE NORTHWARD TREND WITH THE SYSTEM WHEN COMPARED TO THU`S MODEL RUNS. CLOUDS WILL THICKEN SUNDAY AND SNOW WILL ARRIVE OVER THE DELMARVA AND SE PA LATE IN THE AFTERNOON. THE PRECIPITATION WILL OVERSPREAD THE WHOLE AREA SUNDAY NIGHT AND CONTINUE INTO MONDAY. WHILE SNOW WILL BE THE PREDOMINANT P-TYPE...SOME SLEET WILL OCCUR OVER THE DELMARVA AND SRN NJ LATER SUN NIGHT AND INTO MONDAY. PRELIMINARY SNOWFALL ACCUMS LOOK TO BE 4 TO 5 INCHES ACROSS THE SE PA BERKS COUNTY--LEHIGH VALLEY--NRN NJ REGION WITH LIGHTER AMOUNTS BOTH NORTH AND SOUTH. SLEET AND RAIN (FAR SOUTH DEL) WILL REDUCE THE ACCUMS OVER THE DELMARVA AND SRN NJ AREAS. IF THE TRACK CONTINUES A NORTHWARD TREND...THEN MORE RAIN WILL MIX IN OVER THE SRN FORECAST AREA. THE PRECIP WILL END AS SNOW ONCE THE LOW SWEEPS BY MONDAY AFTERNOON BRINGING IN COLDER AIR BEHIND IT. HWO PRODUCT WILL HIGHLIGHT THE POTENTIAL FOR A SUNDAY NIGHT/MONDAY WINTRY WEATHER EVENT. FUTURE FCSTS WILL OFFER BETTER SNOWFALL FCST AND POSSIBLE HEADLINES...SO CHECK BACK LATER TODAY AND SAT/SUN FOR UPDATES. MONDAY NIGHT THRU WEDNESDAY... ANOTHER HIGH PRESSURE SYSTEM WITH COLD AIR WILL AFFECT THE AREA. HIGH TEMPERATURES TUE WILL BE IN THE TEENS AND LOW 20S...SO READINGS AGAIN WILL BE 15 TO 20 DEGREES BELOW NORMAL. MORE WIND CHILL HEADLINES POSSIBLE ACROSS THE FAR NORTH. MODERATING TEMPS WED WITH HIGHS IN THE UPPER 20S TO MID 30S OVER THE REGION. WEDNESDAY NIGHT THRU THURSDAY... THE 00Z GFS AND OLDER 12Z EC MODELS BOTH SHOW ANOTHER H5 TROUGH SWINGING ACROSS THE GREAT LAKES WITH A SFC LOW PRESSURE DEVELOPING AHEAD OF IT. BOTH OF THESE MODELS ALSO SHOW THE LOW PRESSURE SYSTEM DEVELOPING ACROSS THE DEEP SOUTH AND MOVING UP THE EAST COAST. THE LATEST 00Z EC SHOWED THE LOW ALSO...BUT PUSHED IT OFFSHORE THU NGT INTO FRIDAY WITH HIGHER QPF ONLY NEAR THE COAST. WE HAVE GONE ALONG WITH THE WPC AND RAISED POPS UP A BIT FOR THESE PERIODS. THEY ARE STILL ONLY IN THE CHC RANGE HOWEVER. && .AVIATION /09Z FRIDAY THROUGH TUESDAY/... THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY AND SURROUNDING AREAS. MAJORITY OF THE TERMINALS WILL HAVE VFR FOR MOST OF THE DAY. HOWEVER, THERE ARE SEVERAL AREAS OF LIGHT SNOW THAT WILL MOVE INTO THE AREA THRU ABOUT 15Z. A BRIEF PERIOD OF REDUCED VSBY TO MVFR MAY OCCUR AT JUST ABOUT ANY OF THE AIRPORTS. THERE WILL ALSO BE A STRATOCU DECK THAT DEVELOPS BETWEEN 2500-4000 KFT. THE LOWER END OF THAT RANGE WOULD YIELD MVFR CIGS. LOW CLOUDS WILL START TO SCT OUT TOWARD SUNSET. NW WINDS WILL INCREASE THRUOUT THE DAY. EXPECT WINDS SUSTAINED NEAR 20 KT THIS AFTN AND TNGT. GUSTS WILL GENERALLY BE AOB 30 KT THRU ABOUT MID AFTN BUT THEN INCREASE TO 35-40 KT LATE IN THE DAY AND TNGT. OUTLOOK... SATURDAY...VFR WITH WINDY CONDITIONS. SATURDAY NIGHT THRU SUN AFTERNOON...VFR. INCREASING CLOUDS SUNDAY. SUN NIGHT THRU MONDAY...WIDESPREAD IFR/LIFR. SNOW AND MIXED PRECIP. ACCUMULATING SNOW AT PHL. MONDAY NIGHT THRU TUE...IMPROVING CONDITION MON EVE. VFR MON NGT THRU TUE. && .MARINE... NO CHANGES TO THE MARINE HEADLINES. GALE WARNING GOES INTO EFFECT AT 9 AM THIS MORNING. GUSTS WILL GENERALLY BE 25-30 KT THIS MORNING, INCREASING TO 35-40 KT LATE THIS AFTERNOON INTO TONIGHT. SEAS WILL ALSO BUILD TO 5-8 FT BY TONIGHT. WENT SLIGHTLY ABOVE WAVEWATCH GUIDANCE FOR WAVE HEIGHTS. OUTLOOK... SAT AND SAT NIGHT...GALES DIMINISH SAT. SCA CONDITIONS EARLY SAT NIGHT. SUN AND SUN NIGHT...SUB-SCA CONDITIONS. SNOW AND SLEET LATE SUN NIGHT. MON AND MON NIGHT...SCA CONDITIONS EXPECTED. TUE...SCA SEAS ON THE OCEAN EARLY THEN SUB-SCA CONDITIONS. && .PHI WATCHES/WARNINGS/ADVISORIES... PA...WIND ADVISORY FROM 4 PM THIS AFTERNOON TO 6 AM EST SATURDAY FOR PAZ054-055-060>062-070-071-101>106. WIND CHILL ADVISORY FROM MIDNIGHT TONIGHT TO 11 AM EST SATURDAY FOR PAZ054-055. NJ...WIND ADVISORY FROM 4 PM THIS AFTERNOON TO 6 AM EST SATURDAY FOR NJZ001-007>010-012>027. WIND CHILL ADVISORY FROM MIDNIGHT TONIGHT TO 11 AM EST SATURDAY FOR NJZ001. DE...WIND ADVISORY FROM 4 PM THIS AFTERNOON TO 6 AM EST SATURDAY FOR DEZ001>004. MD...WIND ADVISORY FROM 4 PM THIS AFTERNOON TO 6 AM EST SATURDAY FOR MDZ008-012-015-019-020. MARINE...FREEZING SPRAY ADVISORY FROM MIDNIGHT TONIGHT TO 6 PM EST SATURDAY FOR ANZ430-431-450>455. GALE WARNING FROM 9 AM THIS MORNING TO 6 PM EST SATURDAY FOR ANZ430-431-450>455. && $$ SYNOPSIS...O`HARA NEAR TERM...KLEIN SHORT TERM...KLEIN LONG TERM...O`HARA AVIATION...KLEIN/O`HARA MARINE...KLEIN/O`HARA

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