Area Forecast Discussion
Issued by NWS Upton, NY

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599 FXUS61 KOKX 181127 AFDOKX Area Forecast Discussion National Weather Service New York NY 727 AM EDT Wed Oct 18 2017 .SYNOPSIS... High pressure will remain in control through the weekend, with a prolonged period of fair weather. An approaching cold front will bring a chance of rain for the beginning of next week. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... Skies will be sunny as surface high pressure dominates and as an upper trough passes east, with rising heights aloft. A subsidence inversion between 875-900 mb will limit mixing, still with warm air advection temps should reach the upper 60s and lower 70s this afternoon. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM THURSDAY/... As the upper ridge passes east, WAA aloft ahead of another transient upper trough should lead to some high clouds late tonight into Thu morning, with the sky remaining mostly clear overall. Lows tonight should be mostly in the 40s and 50s, with only some isold upper 30s well inland. The subsidence inversion associated with the sfc high as it sinks to the south will be a little stronger, with mixing only to 900-925 mb. This despite plenty of sunshine will yield temps only a little warmer than those expected for today, reaching 70-75, about 10 degrees above average for this time of year. && .LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/... High pressure will continue to dominate through Saturday. The high drifts offshore late Saturday, with return flow developing for the second half of the weekend. This will produce an increase in humidity across the area, particularly from Long Island to Connecticut. Large diurnal spreads of 20-25 degrees through Saturday are likely due to the dry air mass. High temperatures will remain several degrees above average. Southwesterly flow will pick up Monday and Tuesday, as the area starts to get squeezed from an approaching cold front to the west, and high pressure over the Atlantic. The potential exists for the Gulf of Mexico to get tapped with this excess moisture getting transported into the forecast area. Monday and Tuesday could be quite humid as a result. As far as actual rain chances, there are two main shots to contend with. The first is with the approach of a residual convective boundary racing ahead of the main system. Both the GFS and ECMWF have this feature. This has the potential to produce locally heavy showers as it interacts with the deepening moisture on Monday. As the main upper level system gets here Tuesday or slightly later, this produces significant lift and therefore a solid round of moderate to heavy rain. Both the ECMWF and GFS again are pointing in the same direction. The only limiting factor would be if the leading boundary shunts the deeper moisture out to sea. This however in not what the models are currently signaling. && .AVIATION /12Z WEDNESDAY THROUGH SUNDAY/...
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High pressure builds to the south of Long Island into tonight. Very high confidence in VFR through the TAF period. Winds become W-WNW at around 10 kt throughout by mid morning. Winds then slowly back to the SW in the afternoon. Seabreezes are possible at coastal terminals mid-late afternoon. There is a chance for isolated gusts to around 15kt at city terminals late this afternoon. Winds become light and variable during the late afternoon/tonight. NY Metro Enhanced Aviation Weather Support... Detailed information...including hourly TAF wind component fcsts can be found at: http:/www.weather.gov/zny/n90 KJFK TAF Comments: Timing of changes in wind speed and direction could be off +/- 1-2 hours. There is moderate confidence in a seabreeze this afternoon. There is also the possibility for isolated gusts to around 15kt late this afternoon/early this evening. The afternoon KJFK haze potential forecast is green, which implies slant range visibility 7SM or greater outside of cloud. KLGA TAF Comments: Timing of changes in wind speed and direction could be off +/- 1-2 hours. There is low-moderate confidence in a seabreeze this afternoon. There is also the possibility for isolated gusts to around 15kt late this afternoon/early this evening. The afternoon KLGA haze potential forecast is green, which implies slant range visibility 7SM or greater outside of cloud. KEWR TAF Comments: Timing of changes in wind speed and direction could be off +/- 1-2 hours. There is also the possibility for isolated gusts to around 15kt late this afternoon/early this evening. The afternoon KEWR haze potential forecast is green, which implies slant range visibility 7SM or greater outside of cloud. KTEB TAF Comments: Timing of changes in wind speed and direction could be off +/- 1-2 hours. There is also the possibility for isolated gusts to around 15kt late this afternoon/early this evening. KHPN TAF Comments: Timing of changes in wind speed and direction could be off +/- 1-2 hours. There is also the possibility for isolated gusts to around 15kt late this afternoon/early this evening. KISP TAF Comments: Timing of changes in wind speed and direction could be off +/- 1-2 hours. There is moderate confidence in a seabreeze this afternoon. .OUTLOOK FOR 12Z THURSDAY THROUGH SUNDAY... .Thursday-Thursday night...VFR. SW-W winds G15-25kt possible Thursday and Thursday evening. .Friday-Friday night...VFR. NW-N winds G15-25kt possible Friday afternoon and evening. .Saturday-Saturday night...VFR. .Sunday...VFR. SW winds G15-20kt possible.
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&& .MARINE... High pressure settling to the south will produce a WSW flow with gusts up to 20 kt early this morning. Another period of increased WSW flow should bring winds and seas on the ocean close to advy thresholds Wed night, possibly briefly ramping to advy levels on Thu. Quiet conditions expected otherwise. && .HYDROLOGY... No hydrologic issues expected through the weekend. Locally heavy rain is possible during the beginning of next week. && .OKX WATCHES/WARNINGS/ADVISORIES... CT...None. NY...None. NJ...None. MARINE...None. && $$ SYNOPSIS...JMC/Goodman NEAR TERM...Goodman SHORT TERM...Goodman LONG TERM...JMC AVIATION...Maloit MARINE...JMC/Goodman HYDROLOGY...JMC/Goodman

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