Area Forecast Discussion
Issued by NWS Upton, NY

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000 FXUS61 KOKX 291516 AFDOKX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NEW YORK NY 1116 AM EDT FRI MAY 29 2015 .SYNOPSIS...
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HIGH PRESSURE WILL SET UP OVER THE ATLANTIC THROUGH SATURDAY. A COLD FRONT APPROACHES SATURDAY NIGHT AND MOVES THROUGH THE REGION ON SUNDAY. THE FRONT WILL STALL JUST SOUTH OF THE AREA AS WEAK WAVES OF LOW PRESSURE RIDE ALONG IT. HIGH PRESSURE THEN BUILDS IN FROM THE NORTH LATE TUESDAY INTO WEDNESDAY...SHIFTING SOUTH OF THE AREA ON THURSDAY.
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&& .NEAR TERM /THROUGH TONIGHT/...
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NO MAJOR CHANGES MADE WITH THE LATEST UPDATE. THE FORECAST IS ON TRACK. HI PRES RIDGE DRIFTS THRU THE CWA TODAY AND OFFSHORE BY EVE. NORTHERLY FLOW THIS MORNING WILL THEREFORE GRADUALLY VEER TO THE S TODAY. WATER VAPOR SHOWS A VERY DRY AIRMASS BUILDING OVER THE AREA...SO WILL FORECAST A MAINLY CLEAR SKY THRU TONIGHT. THE RETURN FLOW HOWEVER WILL ALLOW FOR INCREASING HUMIDITY DUE TO THE LOW LEVEL MOISTURE INFLUX...AND WITH THE DRY MID LEVELS SOME PATCHY FOG WILL BE POSSIBLE TONIGHT. TEMPS WERE CLOSE TO A BLEND OF GUIDANCE AS THE NUMBERS WERE IN GOOD AGREEMENT. HOWEVER...THERE IS THE POTENTIAL FOR SOME LOCALLY HIGHER TEMPS TODAY PARTICULARLY OVER LONG ISLAND IF THE OPPOSING NORTHEASTERLY FLOW HOLDS THE SEA BREEZE BACK A BIT. THE NAMDNG SUGGESTS NEAR 80 ALONG ROUGHLY THE 495 CORRIDOR. AS A RESULT BUMPED UP HIGHS IN THIS AREA A FEW DEGREES.
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&& .SHORT TERM /SATURDAY/...
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DESTABILIZATION BY AFTERNOON ACROSS WRN ZONES WITH SSW FLOW. THIS WILL AGAIN KEEP ERN PORTIONS OF THE CWA...ESPECIALLY THE COASTS...STABLE. THE NAM HINTS AT TEMPS REMAINING IN THE 60S ACROSS THE S SHORE OF LONG ISLAND AND MUCH OF COASTAL CT. ALTHOUGH THIS MAY BE A BIT MUCH...DID LOWER TEMPS IN THIS AREA AND WILL BANK ON A STABLE AIRMASS. ACROSS THE W...THE MAIN QUESTION WILL BE WHETHER THERE WILL BE A SUFFICIENT TRIGGER. THE JET WILL BE TOO FAR UPSTREAM...BUT THE MODELS DO HINT AT SOME SUBTLE MID LVL FORCING. MAINTAINED THE CURRENT CHANCE POPS FOR THE AFTERNOON HOURS ACROSS APPROXIMATELY THE WRN 1/3 OF THE CWA.
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&& .LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/...
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WESTERN ATLANTIC RIDGE WEAKENS SLIGHTLY AT THE START OF THE LONG TERM PERIOD SATURDAY NIGHT WITH HEIGHTS BEGINNING TO FALL OVER THE AREA. THIS WILL ALLOW A COLD FRONT TO APPROACH FROM THE NORTHWEST. THE BEST CHANCES FOR SHOWERS AND THUNDERSTORMS WILL BE NORTH AND WEST OF NEW YORK CITY EARLY SATURDAY NIGHT...AND THEN POPS INCREASE FROM WEST TO EAST LATE SATURDAY NIGHT AS THE FRONT DRAWS CLOSER. THE FRONT SHOULD BE ENTERING THE INTERIOR SUNDAY MORNING AND MOVING SOUTH THROUGH THE REMAINDER OF THE AREA DURING THE LATE MORNING AND EARLY AFTERNOON HOURS. MODELS GENERALLY AGREE ON THIS SCENARIO ALTHOUGH IT IS POSSIBLE THE TIMING SLOWS DOWN IN LATER RUNS AS THE MODELS CAN BE TOO FAST MOVING FRONTS SOUTH WITH DEEP RIDGING OFF THE COAST. THE FRONT DOES HAVE A GOOD PUSH SOUTH HOWEVER WITH A NEAR 1030 MB HIGH OVER THE GREAT LAKES REGION AND A SHORTWAVE MOVING ACROSS SOUTHEAST CANADA AND NORTHERN NEW ENGLAND. POPS INCREASE TO LIKELY FROM NW TO SE ACROSS THE AREA SUNDAY MORNING INTO THE AFTERNOON. WITH ABUNDANT CLOUD COVER AND PRECIPITATION...INSTABILITY WILL LIKELY BE LOW. HAVE CONTINUED THE WORDING FROM PREVIOUS FORECAST WITH SHOWERS LIKELY WITH A CHANCE OF THUNDERSTORMS. A DEEP MOISTURE FEED AROUND THE RIDGE TAPPING INTO THE GULF OF MEXICO BRINGS HIGH PRECIPITABLE WATERS RANGING FROM 1.5 TO 1.8 INCHES. LOCALLY HEAVY RAINFALL IS POSSIBLE WITH ANY SHOWERS IN THIS AIRMASS. SHOWERS CONTINUE SUNDAY NIGHT INTO MONDAY AS THE FRONT STALLS JUST SOUTH OF THE AREA. WEAK WAVES OF LOW PRESSURE WILL RIDE ALONG THE BOUNDARY. ALOFT...SOME SHORT WAVE ENERGY...AND THE REGION BEING LOCATED NEAR THE RIGHT ENTRANCE REGION OF A 80-100 KT UPPER LEVEL JET ACROSS NORTHERN NEW ENGLAND AND SOUTHEAST CANADA PROVIDE A LARGER SCALE LIFTING MECHANISM. LOCALLY HEAVY RAINFALL REMAINS A POSSIBILITY THROUGH AT LEAST MONDAY MORNING. POPS WILL SLOWLY TAPER TO HIGH CHANCE IN THE AFTERNOON FOR NORTHERN ZONES...BUT REMAIN LIKELY ACROSS THE SOUTH. POPS CONTINUE TRENDING DOWNWARD MONDAY NIGHT INTO TUESDAY MORNING. HOWEVER...MODELS DIFFER ON THE HANDLING OF A MORE WELL DEFINED SHORT WAVE AT 500 MB LATE MONDAY NIGHT INTO TUESDAY. THE 00Z ECMWF IS SLOWER AND INDICATES A MORE NEUTRAL TILT WHICH ALLOWS WIDESPREAD SHOWER ACTIVITY TO CONTINUE WELL INTO TUESDAY. THE GFS AND CMC SHIFT THE FRONT FURTHER SOUTH WITH A POSITIVELY TILTED SHORTWAVE QUICKER TO MOVE THROUGH. WILL NEED TO SEE IF THE ECMWF IS ON TO SOMETHING AS THE NEW 00Z RUN IS CONSISTENT WITH ITS PREVIOUS 12Z RUN. FOR NOW...FORECAST SHOWS A LOW CHANCE POPS FOR SOUTHERN ZONES TUESDAY MORNING BUT THESE MAY NEED TO BE INCREASED IF THE MODELS COME MORE INTO LINE WITH THE ECMWF. HIGH PRESSURE WILL BUILD INTO THE REGION TUESDAY NIGHT THROUGH WEDNESDAY...AND THEN SHIFT SOUTH INTO THE WESTERN ATLANTIC ON THURSDAY. THIS WILL ALLOW FOR DRIER CONDITIONS TO RETURN. TEMPERATURES WILL BE NEAR NORMAL ON SUNDAY...AVERAGE BELOW NORMAL MONDAY THROUGH WEDNESDAY...AND BE NEAR NORMAL ON THURSDAY.
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&& .AVIATION /11Z FRIDAY THROUGH TUESDAY/...
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HIGH PRESSURE WILL REMAIN OFFSHORE THIS AFTERNOON...THEN SLOWLY RETREATS TO THE EAST TONIGHT. VFR THROUGH THE TAF PERIOD. WINDS BECOME SE AT 10 KT OR LESS BY ERLY AFT...THEN LIGHT AND VARIABLE TONIGHT. NY METRO ENHANCED AVIATION WEATHER SUPPORT... DETAILED INFORMATION...INCLUDING HOURLY TAF WIND COMPONENT FCSTS CAN BE FOUND AT: HTTP:/WWW.ERH.NOAA.GOV/ZNY/N90 (LOWER CASE) KJFK FCSTER COMMENTS: TIMING OF CHANGES IN WIND SPEED/DIRECTION COULD BE OFF +/- 2-3 HOURS. KLGA FCSTER COMMENTS: TIMING OF CHANGES IN WIND SPEED/DIRECTION COULD BE OFF +/- 2-3 HOURS. KEWR FCSTER COMMENTS: TIMING OF CHANGES IN WIND SPEED/DIRECTION COULD BE OFF +/- 2-3 HOURS. THE AFTERNOON KEWR HAZE POTENTIAL FORECAST IS GREEN...WHICH IMPLIES SLANT RANGE VISIBILITY 7SM OR GREATER OUTSIDE OF CLOUD. KTEB FCSTER COMMENTS: TIMING OF CHANGES IN WIND SPEED/DIRECTION COULD BE OFF +/- 2-3 HOURS. KHPN FCSTER COMMENTS: TIMING OF CHANGES IN WIND SPEED/DIRECTION COULD BE OFF +/- 2-3 HOURS. KISP FCSTER COMMENTS: TIMING OF CHANGES IN WIND SPEED/DIRECTION COULD BE OFF +/- 2-3 HOURS. .OUTLOOK FOR 12Z SATURDAY THROUGH TUESDAY... .SATURDAY MORNING...MVFR OR LOWER POSSIBLE. .SATURDAY AFTERNOON...MOST LIKELY VFR. CHANCE OF MVFR IN SHOWERS/THUNDERSTORMS MAINLY TO THE N/W OF CITY TERMINALS. GUSTS TO 20-25KT POSSIBLE WITH SEABREEZE. .SATURDAY NIGHT-TUESDAY MORNING...MVFR OR LOWER AT TIMES. THUNDERSTORMS POSSIBLE SATURDAY NIGHT-SUNDAY NIGHT. .TUESDAY AFTERNOON/NIGHT...BECOMING VFR.
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&& .MARINE...
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HI PRES WILL KEEP WINDS AND SEAS BELOW SCA LEVELS THRU TONIGHT. S FLOW INCREASES THRU THE DAY ON SAT WITH SCA CONDITIONS POSSIBLE BY LATE AFTERNOON...ESPECIALLY THE OCEAN AND S SHORE BAYS. SCA CONDITIONS ARE LIKELY ON THE OCEAN WATERS FROM SATURDAY NIGHT THROUGH TUESDAY. A COLD FRONT WILL BE APPROACHING SATURDAY NIGHT WITH STRONG SOUTHERLY FLOW AHEAD OF IT. SEAS ON THE OCEAN WILL BE NEAR 5 FT AND WINDS COULD GUST UP TO 25 KT. THE FRONT CROSSES THE WATERS ON SUNDAY WITH A STRENGTHENING NE FLOW BEHIND IT. SEAS LIKELY BUILD UP TO 7 FEET ON MONDAY AND CONTINUE INTO TUESDAY ON THE OCEAN.
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&& .HYDROLOGY... THE POTENTIAL CONTINUES FOR AN EXTENDED SIGNIFICANT WIDESPREAD RAINFALL...MAINLY SUNDAY THROUGH MONDAY WITH A COLD FRONT STALLING NEAR THE REGION. IT IS DIFFICULT TO SPECIFY EXACT RAINFALL AMOUNTS...BUT THERE WILL BE POTENTIAL FOR HEAVY RAINFALL ESPECIALLY SUNDAY AND SUNDAY NIGHT INTO MONDAY MORNING WHEN PRECIPITABLE WATERS REACH 1.5 TO 1.8 INCHES. ANY HEAVIER SHOWERS PRODUCE LOCALLY HEAVY RAINFALL AND THEREFORE AT LEAST MINOR FLOODING OF URBAN/POOR DRAINAGE AREAS WILL BE A POSSIBILITY. LOCALIZED FLASH FLOODING CANNOT BE RULED OUT. && .OKX WATCHES/WARNINGS/ADVISORIES... CT...NONE. NY...NONE. NJ...NONE. MARINE...NONE. && $$ SYNOPSIS...JMC/DS NEAR TERM...JMC/DS SHORT TERM...JMC LONG TERM...DS AVIATION...MALOIT MARINE...JMC/DS HYDROLOGY...DS

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