Area Forecast Discussion
Issued by NWS Upton, NY

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000 FXUS61 KOKX 300259 AFDOKX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NEW YORK NY 959 PM EST THU JAN 29 2015 .SYNOPSIS...
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LOW PRESSURE AND AN ASSOCIATED COLD FRONT APPROACH FROM THE WEST TONIGHT WITH THE COLD FRONT PASSING THROUGH LATE TONIGHT INTO EARLY FRIDAY MORNING. AN ARCTIC COLD FRONT WILL FOLLOW FRIDAY AFTERNOON AS THE LOW DEEPENS OFF THE NORTHEAST COAST. HIGH PRESSURE BUILDS IN FRIDAY NIGHT AND SATURDAY. A WINTRY PATTERN WILL PERSIST THROUGH THE MIDDLE OF NEXT WEEK...WITH FRIGID COLD ON SATURDAY AND CHANCES FOR SNOW SUNDAY NIGHT INTO MONDAY...AND AGAIN AROUND WEDNESDAY.
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&& .NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
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CLIPPER SYSTEM APPROACHES FROM THE WEST TONIGHT. A SHORTWAVE EMBEDDED IN A DIGGING UPPER TROUGH WILL PROVIDE LIFT FOR PERIODS OF LIGHT SNOW THROUGH THE OVERNIGHT. WARM ADVECTION AHEAD OF THE LOW IS RAISING BOUNDARY LAYER TEMPERATURES...HOWEVER...PROFILE STILL LOOKS COLD ENOUGH FOR ALL SNOW ON LAND. WARM AIR OVER THE WATERS WILL ALLOW FOR RAIN AND SNOW AND A SLIGHT CHANCE THAT ENOUGH WARM AIR MAY MOVE IN ACROSS THE VERY FAR EASTERN ZONES FOR A MIX OF RAIN AND SNOW. TEMPERATURES WILL HOLD NEARLY STEADY OR ONLY FALL A FEW DEGREES TONIGHT. ADJUSTED POPS SLIGHTLY OVERNIGHT BASED ON LATEST TRENDS AND GUIDANCE. NONE OF THE GUIDANCE IS CAPTURING THE RISE IN SFC TEMPS WELL...BUT WOULD EXPECT THEM TO LEVEL OFF AND HOLD STEADY OR EVEN SLIGHTLY FALL DUE TO EVAP COOLING.
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&& .SHORT TERM /6 AM FRIDAY MORNING THROUGH FRIDAY NIGHT/... THE CLIPPER LOW MOVE THROUGH DURING THE MORNING WITH AN ASSOCIATED COLD FRONT. MEANWHILE THE UPPER TROUGH CONTINUES TO DIG AND BECOME NEGATIVELY TILTED. A STRONG VORT MAX ROUNDS THE BASE OF THE TROUGH FRIDAY AFTERNOON ALLOWING FOR THE LOW TO RAPIDLY DEEPEN OFF THE NORTHEAST COAST. AN ARCTIC FRONT MOVES THROUGH FRIDAY AFTERNOON AS THE LOW DEEPENS. NORTHWEST WIND WILL INCREASE AND BECOME GUSTY AS ARCTIC AIR FLOWS IN. LATE FRIDAY AFTERNOON AND FRIDAY NIGHT SUSTAINED WIND AND GUSTS ARE EXPECTED TO FALL JUST BELOW ADVISORY LEVELS...WITH THE HIGHEST WIND ALONG THE COAST. THE COMBINATION OF COLD AIR AND GUSTY WIND WILL PRODUCE WIND CHILLS WELL BELOW ZERO FRIDAY NIGHT...WITH WIND CHILLS AT ADVISORY LEVELS BY LATE FRIDAY NIGHT. BEING LATE THIRD PERIOD INTO FOURTH PERIOD WILL HOLD OFF ON A WIND CHILL ADVISORY. && .LONG TERM /SATURDAY THROUGH THURSDAY/... 980S LOW SPINNING NEAR NOVA SCOTIA WILL KEEP GUSTY NW FLOW LOCKED IN ON SAT...PRODUCING WIND CHILLS MAINLY AOB ZERO FOR MOST OF THE DAY. AS WINDS SLACKEN LATE...WIND CHILLS WILL LIKELY RISE INTO THE SINGLE DIGITS. H85 WINDS IN THE GFS ARE AROUND 55-60KT AT 12Z SAT...SO THERE IS THE POTENTIAL FOR WIND ADVY EARLY WITH GUSTS IN THE 45-50 MPH RANGE. SUBSIDENCE ON THE WRN FRINGE OF THE SYS SHOULD AID IN THE GUST POTENTIAL...WHILE AT THE SAME TIME CLEARING OUT THE SKIES. WEAK HI PRES RIDGE SAT NGT SO MUCH LIGHTER WINDS INTO SUN. MODELS LINING UP WITH THE NEXT SYS FOR SUN NGT AND MON. THE 12Z GFS AND ECMWF ARE VIRTUALLY THE SAME WRT THE TRACK AND INTENSITY. AT 18Z MON THE LOW CENTERS WERE APPROXIMATELY 60 MILES APART AND ABOUT 130 MILES S OF THE BENCHMARK. MOST OF THE GFS ENSEMBLE MEMBERS WERE CLUSTERED ON THIS SOLN. EXTENSIVE AREA OF MID LVL MOISTURE WITH THE SYS...SO WITH HIGH SLR/S AT LEAST LGT-MDT ACCUMS POSSIBLE. BASED ON THE PROGRESSIVE NATURE...IT LOOKS LIKE A 4-8 INCH POTENTIAL ATTM. THIS OF COURSE CAN CHANGE...IN FACT A SRN TRACK COULD LEAVE THE CWA WITH JUST FLURRIES. AS AN ASIDE...THE 12Z MEX HAS CAT 8 SNOWFALL FOR ALL SITES. HI PRES MON NGT AND TUE. SUNNY ON TUE AS A RESULT. THE GULF OPENS UP MIDWEEK POTENTIALLY IN TANDEM WITH ANOTHER NRN STREAM UPR TROF. ECMWF PROGS LOW PRES HEADING TOWARDS CAPE COD. THIS REFLECTS THE IDEA OF LOW PRES EXHIBITED IN THE 00Z RUN. THE GFS IS LESS ORGANIZED. INCLUDED 30 POPS FOR PCPN WED. && .AVIATION /03Z FRIDAY THROUGH TUESDAY/...
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LOW PRESSURE APPROACHES FROM THE WEST TONIGHT...CROSSES THE AREA FRIDAY MORNING...THEN EXITS TO THE EAST AS IT DEEPENS FRIDAY AFTERNOON. MVFR/IFR CONDITIONS DEVELOP IN PERIODS OF LIGHT SNOW BETWEEN 03Z AND 05Z FOR CITY TERMINALS...AND A COUPLE HOURS LATER FOR EASTERN TERMINALS. STEADIEST SNOW LIKELY TOWARDS DAYBREAK AND MORNING FOR CITY AND EASTERN TERMINALS WITH IFR CONDS. SNOW MAY BE BRIEFLY MODERATE WITH LIFR CONDS. CONDITIONS GRADUALLY IMPROVE TO MVFR FROM LATE MORNING TO EARLY AFTERNOON...AND THEN VFR LATE AFTERNOON. ISOLATED SNOW SHOWERS/FLURRIES POSSIBLE IN THE AFTERNOON. GENERALLY EXPECTING 1-2 INCH SNOWFALL WITH HIGHEST AMOUNTS ACROSS NORTHERN TERMINALS. LIGHT S WINDS OVERNIGHT...ALTHOUGH A BRIEF PERIOD OF OCCASIONAL S GUSTS TO 20 KT POSSIBLE AT COASTAL TERMINALS THROUGH ABOUT 06Z. WINDS SHIFT SW-W-NW FRIDAY MORNING...WITH NW WIND GUSTS TO 25-35 KT AFTERNOON. .OUTLOOK FOR 00Z FRIDAY NIGHT THROUGH TUESDAY... .FRIDAY NIGHT-SATURDAY...VFR. NW WINDS G30-35 KT LIKELY. A FEW 40 KT GUSTS POSSIBLE. .SATURDAY NIGHT...VFR. NW WIND G 20-30KT POSSIBLE EARLY. .SUNDAY...VFR. NW WIND G15-20KT POSSIBLE. .SUNDAY NIGHT- MONDAY..CHANCE OF SNOW WITH IFR CONDITIONS. NE-N WIND G25-35KT POSSIBLE. .MONDAY NIGHT...BECOMING VFR FROM W TO E AS ANY SNOW COMES TO AN END. N-NW WIND G20-25KT POSSIBLE. .TUESDAY...VFR.
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&& .MARINE...
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LOW PRESSURE APPROACHES FROM THE WEST TONIGHT WITH AN INCREASING SOUTHERLY FLOW ALLOWING FOR SEAS ON THE OCEAN TO BUILD TO SMALL CRAFT LEVELS OVERNIGHT. IN ADDITION SOME SOUTHERLY WIND GUSTS...MAINLY OVER THE OUTER FORECAST WATERS...MAY REACH SMALL CRAFT LEVELS. AS LOW PRESSURE PASSES THROUGH THE WATERS LATE TONIGHT INTO EARLY FRIDAY THE WIND WILL DIMINISH AND WILL LIKELY FALL BELOW SMALL CRAFT FOR A FEW HOURS. THEN AS THE LOW AND ASSOCIATED COLD FRONT MOVE THROUGH WIND SHIFTS TO THE NORTHWEST AND INCREASE AS THE LOW DEEPENS. AN ARCTIC COLD FRONT CROSSES FRIDAY AFTERNOON. THE DEEPENING LOW AND STRONG COLD ADVECTION WILL ALLOW THE WIND OVER THE WATERS TO GUST TO GALE FORCE FRIDAY AFTERNOON INTO SATURDAY. THE SMALL CRAFT ADVISORY REMAINS AS POSTED...AND THE GALE WARNING WAS EXTENDED THROUGH SATURDAY. GALES WILL WIND DOWN SAT NGT AS LOW PRES PASSES N OF NOVA SCOTIA. SEAS MAY BE CLOSE TO 5 FT ON THE EXTREME ERN OCEAN SUN...ELSEWHERE WINDS AND WAVES WILL BE BLW SCA LVLS. SCA WINDS LIKELY MON AS LOW PRES DEEPENS E OF THE WATERS. IMPROVING COND ON TUE AS HI PRES BUILDS OVER THE REGION.
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&& .HYDROLOGY... ONE TO TWO TENTHS OF AN INCH OF LIQUID EQUIVALENT IS EXPECTED FROM LATE TONIGHT INTO FRIDAY AFTERNOON WITH THE PRECIPITATION FALLING AS SNOW. LOW PRES SUN NGT AND MON WILL BRING THE POTENTIAL FOR LESS THAN AN INCH OF LIQUID EQUIVALENT. PCPN LIKELY TO BE ALL SNOW. && .OKX WATCHES/WARNINGS/ADVISORIES... CT...NONE. NY...NONE. NJ...NONE. MARINE...GALE WARNING FROM 1 PM FRIDAY TO 6 PM EST SATURDAY FOR ANZ330- 335-338-340-345-350-353-355. SMALL CRAFT ADVISORY FROM 1 AM TO 1 PM EST FRIDAY FOR ANZ350- 353-355. && $$

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