Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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000 FXUS61 KPHI 301758 AFDPHI AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MOUNT HOLLY NJ 1258 PM EST FRI JAN 30 2015 .SYNOPSIS... WINDY AND PROGRESSIVELY COLDER CONDITIONS ARE MOVING OVER THE AREA BEHIND A COLD FRONT THAT MOVED THROUGH THIS MORNING. 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/... THE COLD FRONT HAS MOVED THROUGH MOST OF THE AREA. TEMPERATURES ARE HOLDING STEADY, BUT WILL BEGIN TO DROP LATER THIS AFTERNOON. STRONG NORTHWEST WINDS WILL CONTINUE, WITH GUSTS OVER 40 MPH POSSIBLE AT TIMES. SOME RESIDUAL SNOW SHOWER ACTIVITY...ESPECIALLY OVER THE NORTH...WITH SUBSIDE AS THE AFTERNOON WEARS ON. SKIES WILL REMAIN CLOUDY. && .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 /18Z FRIDAY THROUGH WEDNESDAY/... THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY AND SURROUNDING AREAS. EXPECT MVFR CEILINGS BETWEEN 2000 AND 4000 FEET AT MANY TAF SITES THIS AFTERNOON...THEN IMPROVING THIS EVENING AS SKIES CLEAR. THE BIG ISSUE WILL BE THE STRONG NORTHWEST WINDS, GUSTING BETWEEN 30 AND 40 KT AT TIMES. THESE WINDS WILL CONTINUE THROUGH MOST OF SATURDAY BEFORE SUBSIDING LATE SATURDAY AFTERNOON. 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 HRU TUE. && .MARINE... NO CHANGES TO THE MARINE HEADLINES. GALE WARNING CONTINUE. EXPECT GUSTS IN THE 35-40 KT LATE THIS AFTERNOON INTO TONIGHT. SEAS WILL ALSO BUILD TO 5-8 FT BY TONIGHT. 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 UNTIL 6 PM EST SATURDAY FOR ANZ430-431-450>455. && $$ SYNOPSIS...O`HARA/MIKETTA NEAR TERM...MIKETTA SHORT TERM...KLEIN/MIKETTA LONG TERM...O`HARA AVIATION...KLEIN/MIKETTA/O`HARA MARINE...KLEIN/MIKETTA/O`HARA

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