Area Forecast Discussion
Issued by NWS Upton, NY

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000 FXUS61 KOKX 181817 AFDOKX Area Forecast Discussion National Weather Service New York NY 217 PM 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/... Minor updates this afternoon to reflect current wind trends with a slightly slower arrival of the sea breeze. Otherwise forecast remains on track. 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 WEDNESDAY/... 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 /18Z WEDNESDAY THROUGH MONDAY/...
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High pressure builds southeast of the region through the TAF period with a high confidence of VFR continuing for most terminals. Only exception would be KSWF where there is a low chance of some MVFR patchy fog overnight into daybreak Thursday. The wind forecast is moderate confidence due some uncertainty the exact timing of the sea breeze this afternoon and how far north the sea breeze moves. Wind speeds stay 10 kt or less through tonight with winds picking up Thursday afternoon to around 10 kt, gusting to 15-20 kt. 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: Wind direction could be 20-30 degrees off at times this afternoon. KLGA TAF Comments: Wind direction could be 20-30 degrees off at times this afternoon. KEWR TAF Comments: Wind direction could be 20-30 degrees off at times this afternoon. KTEB TAF Comments: Wind direction could be 20-30 degrees off at times this afternoon. KHPN TAF Comments: Wind direction could be 20-30 degrees off at times this afternoon. KISP TAF Comments: Wind direction could be 20-30 degrees off at times this afternoon. .OUTLOOK FOR 18Z THURSDAY THROUGH MONDAY... .Thursday Afternoon-Thursday night...VFR. SW-W winds G15-25kt possible afternoon-evening. .Friday-Friday night...VFR. NW-N winds G15-25kt possible Friday afternoon and evening. .Saturday-Sunday night...VFR. .Monday...MVFR possible with chances of showers later during day. SW wind gusts near 15kt.
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&& .MARINE... High pressure settling to the south will produce a WSW flow. 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...MD/Goodman SHORT TERM...Goodman LONG TERM...JMC AVIATION...JM MARINE...JMC/Goodman HYDROLOGY...JMC/Goodman

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