Area Forecast Discussion
Issued by NWS Upton, NY

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000 FXUS61 KOKX 171549 AFDOKX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NEW YORK NY 1149 AM EDT FRI MAY 17 2013 .SYNOPSIS...
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HIGH PRESSURE BUILDS IN THIS AFTERNOON...THEN MOVES EAST SATURDAY. A WAVE OF LOW PRESSURE ALONG A STATIONARY FRONT ACROSS THE MID ATLANTIC STATES BEGINS TO RETURN NORTHWARD SUNDAY INTO MONDAY. THE FRONT THEN REMAINS IN CLOSE PROXIMITY TO THE AREA THROUGH MID WEEK UNTIL A COLD FRONTAL PASSAGE OCCURS LATE IN THE WEEK.
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&& .NEAR TERM /UNTIL 6 PM THIS EVENING/...
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BKN-OVC JET CIRRUS EXPECTED TO SLOWLY LIFT NE AND THIN PER LATEST NAM SIMULATED IR IMAGERY. THUS...STILL EXPECTING MOSTLY SUNNY THIS AFTN. WEAKENING OF BOUNDARY LAYER WINDS RESULTS IN SEA BREEZE DEVELOP...THOUGH THIS WILL LIKELY BE DELAYED IN EASTERN SECTIONS. TEMPS ON TACK WITH FCST WITH HIGHS IN THE LOWER 70S.
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&& .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM SATURDAY/... WEAK TROUGH/VORT MAX TRACKS TO THE SOUTH IN SPLIT FLOW WITH OVERALL RIDGE BUILDING AND REMAINING TO THE WEST THROUGH THIS TIME FRAME. DEEPER MOISTURE IS POSSIBLE BY LATE SATURDAY...WITH THE BEST CHANCE FOR SHOWERS OR THUNDERSTORMS TO OUR SOUTHWEST CLOSER TO UPPER TROUGH. OTHERWISE...MAINLY HIGHER LEVEL CLOUDS SPILL OVER THE RIDGE TONIGHT AND INTO SATURDAY. THERE MAY BE A FEW MORE CLOUDS SATURDAY AFTERNOON...BUT WILL KEEP THE FCST DRY AT THIS TIME. TEMPS SHOULD RADIATE TONIGHT AS WINDS LIGHTEN. THIS DEPENDS ON THE EXTENT OF HIGH CLOUDS THOUGH...BUT MOS SHOWS LARGE MINIMUM TEMP DIFFERENCES BETWEEN HEAT ISLAND LOCATIONS OF NYC METRO AND THE USUAL COOLER SPOTS. 50S AND 40S WITH A MOS BLEND FOLLOWED. ON SATURDAY...ONSHORE FLOW WILL SETUP THE USUAL COOLER TEMPS NEAR THE COAST...AND WARMER READINGS ACROSS THE INTERIOR AWAY FROM THE WATER INFLUENCE. TEMPS IN THE 70S...A FEW DEGREES COOLER NEAR THE SOUTH FACING SHORES. && .LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/... A MUDDLED FRONTAL BOUNDARY WILL REMAIN IN CLOSE PROXIMITY TO THE TRI-STATE AREA FOR MUCH OF THIS PERIOD WITH BOUTS OF SHOWERS AND INCREASINGLY WARM...HUMID CONDITIONS. THERE ARE SOME DISCREPANCIES AMONGST THE GLOBAL MODELS WITH THE MAGNITUDE OF AN UPPER TROF ACROSS EASTERN CANADA AS AN UPPER RIDGE OVER THE MS VLY TRANSLATES EAST THROUGH THE UPCOMING WEEK. BY THE END OF THE WEEK...AN UPPER TROF EVENTUALLY MOVES ACROSS THE GREAT LAKES AND INTO THE ST LAWRENCE RIVER VALLEY...PHASING WITH A DEEPENING UPPER LOW OVER EASTERN CANADA. THE UPPER RIDGE THEN BUILDS OFFSHORE INTO THE WESTERN ATLANTIC. THE INTERACTION OF ALL THESE FEATURES WILL BE CRITICAL AS TO WHETHER THE AREA GETS INTO THE WARM SECTOR...OR WHETHER THE PICTURE IS MORE MUDDLED WITH A FRONTAL BOUNDARY MEANDERING ACROSS THE REGION FOR MUCH OF THE TIME PERIOD WITH CLOUDS AND CONVECTION. THE 00Z GFS AND 12Z ECMWF WERE AT ODDS WITH THE FRONTAL BOUNDARY LOCATION WITH ECMWF KEEPING THE AREA COOLER...AND GENERALLY IN THE VICINITY OF THE FRONT...WHILE THE GFS KEPT IT NORTH. THE GEFS AND ECENS SUPPORT THE WARMER SOLUTION. THUS...THE FORECAST HAS DISCOUNTED THE COLDER 12Z ECMWF. IN FACT...A QUICK GLIMPSE AT THE 00Z ECMWF SUPPORTS A TREND TOWARD THE WARMER SOLUTIONS. ON SUN...A FRONTAL WAVE TO THE SOUTH ALONG A STATIONARY FRONT WILL BEGIN TO LIFT SLOWLY NORTHWARD INTO TUE...INCREASING THE CHANCES FOR SHOWERS. THIS WAVE DAMPENS OUT AS THE FRONT SETTLES JUST NORTH OF THE REGION. ONCE AGAIN...THIS IS THE TRICKY PART OF THE FORECAST WHERE THAT BOUNDARY ACTUALLY STALLS. THE FORECAST AREA IS THEN EXPECTED TO RESIDE IN THE WARM SECTOR TUE-THU WITH CHANCES OF SCT CONVECTION DURING THE TIME. SHORT WAVES AT THE SOUTHERN EDGE OF THE WESTERLIES MAY ALSO ALLOW FOR CONVECTIVE COMPLEXES TO FORM AND TRACK WEST TO EAST ALONG THIS BOUNDARY. THE DETAILS OF SUCH REMAIN TO UNCERTAIN TO DISCUSSING ANY TIMING AND RAINFALL POTENTIAL. HIGHS WILL MODERATE INTO THE 70S BY TUE...AND QUITE POSSIBLY THE 80S INLAND. A SW FLOW FOR MUCH OF THE PERIOD WILL KEEP COASTAL AREAS COOLER...BUT IT WILL BE MUGGY WITH DEW POINTS APPROACHING 60. LOWS IN THE 50S WILL CREEP UP TO AROUND 60 DURING THE SAME TIME. && .AVIATION /16Z FRIDAY THROUGH TUESDAY/...
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HIGH CONFIDENCE VFR THROUGH THE TAF PERIOD AS HIGH PRESSURE BUILDS IN FROM THE GREAT LAKES. NW SFC FLOW CONTINUES TO WEAKEN INTO THE AFTERNOON ALLOWING FOR COASTAL SEA BREEZES TO FORM DURING THE MID TO LATE AFTERNOON. 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) KEWR FCSTER COMMENTS: WINDS REMAIN ON A GENERAL LOWERING TREND. LOW CHANCES FOR GUST REPORTS THIS AFTERNOON. CONFIDENCE IN SEA BREEZE IS INCREASING AND EXPECT SEA BREEZE TO REACH EWR IN THE 21Z TO 23Z TIME-FRAME SHIFTING WIND DIRECTION TO 150. THE AFTERNOON KEWR HAZE POTENTIAL FORECAST IS GREEN...WHICH IMPLIES SLANT RANGE VISIBILITY 7SM OR GREATER OUTSIDE OF CLOUD. KJFK FCSTER COMMENTS: INCREASING CONFIDENCE IN SEA BREEZE SHIFTING WIND DIRECTION PLUS OR MINUS 1 HOUR OF 20Z. KLGA FCSTER COMMENTS: NORTHEAST (040) SOUND BREEZE LIKELY AFTER 19Z. ATLANTIC SEA BREEZE MAY REACH THE TERMINAL AROUND 23Z CAUSING A SHIFT TO SOUTH. KTEB FCSTER COMMENTS: MODERATE CONFIDENCE IN THE SEA BREEZE REACHING THE TERMINAL BY SUNSET. KHPN FCSTER COMMENTS: AMENDMENTS NOT SCHEDULED. KISP FCSTER COMMENTS: SEA BREEZE COULD MOVE THROUGH THE TERMINAL AFT 20Z. .OUTLOOK FOR 12Z SATURDAY THROUGH TUESDAY... .SAT-SUN...VFR. .SUN NGT-MON...IFR POSSIBLE AT NIGHT INTO MORNING. SHOWERS AND POSSIBLE TSTMS. .TUE...CHANCE OF SUB-VFR CONDS IN SHOWERS.
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&& .MARINE...
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HIGH PRESSURE CONTINUES TO BUILD IN THIS AFTERNOON. COASTAL SEA BREEZES DEVELOP BY MID AFTERNOON IN THE NY BIGHT...A BIT LATER ON THE SOUND AND FOR EASTERN LONG ISLAND. OVERALL...WINDS ARE EXPECTED TO REMAIN RATHER LIGHT UNDER 15 KTS. SEAS OVER THE OCEAN WATERS WILL CONTINUE TO SUBSIDE PER WAVE WATCH MODEL...WHICH CLOSELY MATCHES OBS. WINDS LIGHTEN FURTHER TONIGHT...THEN THE CENTER OF THE HIGH MOVES OFFSHORE SATURDAY. WINDS SHIFT AROUND TO THE EAST OR SOUTHEAST BY SATURDAY...BUT SUB SCA CONDITIONS ARE ANTICIPATED. ON SUN...A WARM FRONT BEGINS TO APPROACH FROM THE SW. THIS WILL RESULT IN A STRENGTHENING PRES GRAD ON THE WATERS AND A CHC FOR SCA E/SE WINDS. ON THE OCEAN...POTENTIAL IS HIGH FOR AT LEAST 5 FT SEAS. SEAS AOA 5 FT ARE POSSIBLE THRU MID WEEK ON THE OCEAN. ELSEWHERE... PREVAILING SLY COMPONENT FLOW WILL MAKE IT DIFFICULT TO REACH SCA LVL WINDS THRU THE PERIOD ATTM.
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&& .HYDROLOGY... DRY WEATHER IS EXPECTED THROUGH SATURDAY. ALTHOUGH WIDESPREAD HVY RAIN EVENTS ARE NOT EXPECTED SUN-THU...THERE WILL BE THE POTENTIAL FOR TSTMS...ESPECIALLY AFTER MON...WHICH WOULD BE CAPABLE OF PRODUCING LOC HVY RAINFALL AMOUNTS. && .OKX WATCHES/WARNINGS/ADVISORIES... CT...NONE. NY...NONE. NJ...NONE. MARINE...NONE. && $$ SYNOPSIS... NEAR TERM... SHORT TERM...PW LONG TERM...DW AVIATION...TONGUE MARINE...DW/PW HYDROLOGY...DW

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