Area Forecast Discussion
Issued by NWS Upton, NY

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000 FXUS61 KOKX 310404 AFDOKX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NEW YORK NY 1204 AM EDT FRI OCT 31 2014 .SYNOPSIS... HIGH PRESSURE WILL BUILD IN OVERNIGHT. LOW PRESSURE DEVELOPS OFF THE MID ATLANTIC COAST FRIDAY AND TRACKS NORTHEAST. A SECONDARY LOW FORMING OFF THE MID ATLANTIC COAST ON SATURDAY WILL INTENSIFY AND HEAD NORTHEAST TO THE CANADIAN MARITIMES BY SUNDAY EVENING. HIGH PRESSURE WILL BUILDS IN BEHIND THIS STORM FROM MONDAY INTO TUESDAY. A WARM FRONT WILL PASS TO THE NORTH ON TUESDAY... FOLLOWED BY A SERIES OF FAST MOVING COLD FRONTS WEDNESDAY INTO THURSDAY. && .NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
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MINOR CHANGES MADE THIS UPDATE...MAINLY TO CLEAN UP HOURLY TEMPERATURE/DEWPOINT TRENDS OVER THE NEXT FEW HOURS...BASED ON LATEST GUIDANCE AND TRENDS IN OBSERVATIONS. THE FORECAST OVERALL APPEARS ON TRACK. WITH WEAK PRESSURE GRADIENT ACROSS THE REGION...WIND IS NEARLY CALM. STILL ON TRACK MOSTLY CLEAR CONDITIONS OVERNIGHT...HOWEVER CANNOT RULE OUT FEW-SCT LOWER CLOUDS FROM TIME TO TIME. LOW TEMPS TONIGHT SHOULD BE NEAR TO SLIGHTLY BELOW NORMAL.
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&& .SHORT TERM /6 AM FRIDAY MORNING THROUGH FRIDAY NIGHT/...
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SHORTWAVE AND WEAK POSITIVE VORTICITY ADVECTION TRACKS OFF THE MID ATLANTIC COAST...WITH SFC LOW PRESSURE DEVELOPING OFF THE CAROLINAS. MORE POTENT SHORTWAVE CARVES OUT LOW PRESSURE FRIDAY NIGHT AS IT ROUNDS THE BASE OF THE MAIN TROUGH OVER THE SOUTHEAST STATES. WEAK INVERTED TROUGH EXTENDS NW FROM THE WESTERN ATLANTIC LOW LATER FRIDAY AND FRIDAY NIGHT. WITH SOME SUPPORT ALOFT...AND A MOISTENING COLUMN DUE TO INCREASING EAST/NORTHEAST FLOW BELOW H8 HPA...EXPECT LIGHT RAIN TO DEVELOP FRIDAY AFTERNOON. RAIN CHANCES INCREASE FRIDAY NIGHT...WITH THE BETTER CHANCE ACROSS THE EASTERN ZONES. TEMPS ARE EXPECTED TO AVERAGE SLIGHTLY BELOW NORMAL DUE TO INCREASING CLOUDS AND NE FLOW. NEAR NORMAL READINGS ANTICIPATED FRIDAY NIGHT. FOLLOWED A MOS BLEND.
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&& .LONG TERM /SATURDAY THROUGH THURSDAY/...
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GUIDANCE REMAINS MOSTLY CONSISTENT ON THE EVOLUTION OF A STORM DEVELOPING OFF THE COAST THIS WEEKEND. FIRST...LOW PRESSURE MOVING ALONG AN OFFSHORE FRONT WILL BRING MOSTLY LIGHT RAIN TO THE AREA...ESPECIALLY OVER ERN LONG ISLAND/SE CT WITH CAT POP...WITH LIKELY POP AS FAR BACK AS NYC METRO. THERE ARE DIFFERENCES IN TIMING AND RAINFALL AMOUNTS DURING THE DAY SAT BETWEEN THE LATEST RUNS OF THE MODEL GUIDANCE...WITH THE LATEST GFS SOONER AND A LITTLE FARTHER EAST...AND THE ECMWF WETTER AND LATER OUT EAST...HAVE SMOOTHED OUT THESE DIFFERENCES FOR NOW WITH A GENERAL ALL DAY EVENT. FOCUS OF RAIN SHOULD GRADUALLY SHIFT TO THE EAST SAT NIGHT...WITH DECREASING POP AS THIS FIRST LOW LIFTS TO THE NE. PRECIP COULD BRIEFLY END AS SOME SNOW OR A RAIN/SNOW MIX IN THE HIGHEST ELEVATIONS WELL NORTH/WEST. AS A STRONGER LOW FORMS NEAR CAPE HATTERAS AND THEN TRACKS OUTSIDE THE 40N/70W BENCHMARK BY DAYBREAK SUNDAY...ITS RAINFALL SHOULD REMAIN OFFSHORE AS IT FAILS TO PHASE WITH THE UPPER TROUGH TO ITS WEST. ITS MORE IMPORTANT IMPACTS WILL BE AND COOLER CONDITIONS ON SUNDAY...WITH A BRISK N FLOW AS AS THE LOW INTENSIFIES AND THE PRESSURE GRADIENT TIGHTENS AROUND BETWEEN IT AND BUILDING HIGH PRESSURE TO THE WEST. THERE SHOULD ALSO BE PLENTY OF INSTABILITY STRATO CUMULUS AS AN UPPER TROUGH MOVES ACROSS. HIGHS WILL ONLY BARELY REACH 50 IN NYC METRO AND LONG ISLAND...AND REMAIN IN THE 40S INLAND. WINDS WILL DIMINISH SOMEWHAT SUNDAY NIGHT UNDER MOSTLY CLEAR SKIES...BUT REMAIN STRONG ENOUGH TO PREVENT THE BOUNDARY LAYER FROM COMPLETELY DECOUPLING IN MOST PLACES. ASA RESULT STUCK CLOSE TO GUIDANCE LOWS FOR SUNDAY NIGHT AND DID NOT UNDERCUT...WITH LOWS 25-30 WELL INLAND...LOWER 30S MOST ELSEWHERE...AND MID 30S FOR NYC. AFTER ONE MORE COOL DAY ON MON WITH HIGHS AGAIN IN THE UPPER 40S AND LOWER 50S...TEMPS SHOULD MODERATE BACK TO NEAR NORMAL FOR THE MID WEEK PERIOD AS A WARM FRONT PASSES TO THE NORTH AND HIGH PRESSURE PASSES TO THE EAST. SHOULD THEN SEE A SERIES OF WEAK...FAST MOVING COLD FRONTS PASSING THROUGH IN FAST QUASI- ZONAL FLOW...WITH CHANCE POP FOR RAIN SHOWERS NORTH/WEST OF NYC ON WED...AND THROUGHOUT THE AREA WED NIGHT INTO THU.
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&& .AVIATION /04Z FRIDAY THROUGH TUESDAY/...
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HIGH PRESSURE BUILDS NORTH AND EAST OF THE AREA THROUGH FRIDAY...WHILE LOW PRESSURE DROPS SE ACROSS THE GREAT LAKES. A SECONDARY COASTAL LOW THEN DEEPENS ON FRIDAY AND TRACKS NE OFF THE MID ATLANTIC COAST. EXPECT MAINLY VFR CONDITIONS WITH POSSIBLE MVFR CONDITIONS BY LATE FRI AFTERNOON. HIGHER CONFIDENCE IS AFTER 00Z SAT WITH THE ONSET OF -RA. WINDS CONTINUE TO VEER TO THE N OVERNIGHT AND NE ON FRIDAY. .OUTLOOK FOR 00Z SATURDAY THROUGH TUESDAY... .FRI NIGHT-SAT NIGHT...MVFR OR LOWER. PCPN MAINLY RAIN...BUT SNOW MAY MIX IN ACROSS THE INTERIOR SUN NIGHT. NE-N WINDS 15-20G25-35KT. .SUNDAY...MAINLY VFR. AFT STRATO CU WITH ISOLATED FLURRIES/SPRINKLES. NW WINDS 20-25G30-35KT. .MONDAY AND TUESDAY...VFR.
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&& .MARINE...
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MADE MINOR CHANGES THIS UPDATE TO REFLECT THE LATEST TRENDS IN OBSERVATIONS AND GUIDANCE. WIND REMAINS NORTHWEST AROUND 12 KT OR LESS WITH MINIMAL GUSTS...AND SHOULD DIMINISH OVERNIGHT. SEAS RUNNING 2 TO 3 FT ON THE OCEAN AND 1 FT OR LESS ON THE REMAINDER OF THE WATERS. WINDS REMAIN GENERALLY 10 KT OR LESS THROUGH FRIDAY MORNING... THEN WINDS INCREASE FRIDAY AFTERNOON AS THE PRESSURE GRADIENT BEGINS TO INCREASE...WITH THIS MOST NOTABLE AT FIRST OVER THE EASTERN MOST COASTAL OCEAN WATERS. E-NE WINDS CONTINUE TO INCREASE FRIDAY NIGHT TO SCA THRESHOLDS. RELATIVELY TRANQUIL SEAS BUILD LATE FRIDAY AND FRIDAY NIGHT AS THE WINDS INCREASE. SCA CONDITIONS ARE EXPECTED TO CONTINUE SAT...BUT IT IS STILL UNCERTAIN WHETHER GALES WILL DEVELOP THAT EARLY DUE TO TIMING UNCERTAINTY OF AN INITIAL LOW PASSING TO THE SE. GALES APPEAR MORE LIKELY LATE SAT NIGHT INTO SUNDAY AS STRONGER LOW PRESSURE DEVELOPS AND PASSES TO THE SE...WITH CAA OVER STILL RELATIVELY MILD WATERS AND A TIGHTENING PRESSURE GRADIENT. AFTER SOME LINGERING GALES ON THE ERN OCEAN WATERS SUNDAY EVENING...SCA CONDITIONS SHOULD OTHERWISE FOLLOW FOR SUNDAY NIGHT INTO MON FOR MOST WATERS. THEN QUIET CONDITIONS SHOULD RETURN TO ALL WATERS BY MON NIGHT. INCREASING SW FLOW AHEAD OF A COLD FRONT COULD BRING A RETURN OF SCA CONDITIONS TO THE ERN OCEAN WATERS LATE TUE NIGHT-WED.
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&& .HYDROLOGY... RAINFALL FROM FRI NIGHT THROUGH SAT NIGHT SHOULD REMAIN UNDER A HALF INCH...WITH THE HIGHER AMOUNTS GENERALLY ACROSS ERN LONG ISLAND AND SE CT. NO SIGNIFICANT HYDROLOGIC IMPACT EXPECTED. && .OKX WATCHES/WARNINGS/ADVISORIES... CT...NONE. NY...NONE. NJ...NONE. MARINE...SMALL CRAFT ADVISORY FROM 6 PM FRIDAY TO 6 AM EDT SATURDAY FOR ANZ330-335-338-340-345-350-353-355. && $$ SYNOPSIS...GOODMAN/PW NEAR TERM...MALOIT/MET/PW SHORT TERM...PW LONG TERM...GOODMAN AVIATION...DW MARINE...MALOIT/MET/GOODMAN/PW HYDROLOGY...GOODMAN/PW

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