Area Forecast Discussion
Issued by NWS Upton, NY

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000 FXUS61 KOKX 152204 AFDOKX Area Forecast Discussion National Weather Service New York NY 604 PM EDT Tue Aug 15 2017 .SYNOPSIS... A weak cold front moves across the region tonight. High pressure returns Wednesday into Wednesday night. A warm front lifts to the north late Thursday night as a slow moving cold front approaches the area from the west. The cold front crosses the region on Saturday. High pressure then builds into the region for the start of the new work week. && .NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/...
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Forecast is generally on track. Just made some minor adjustments to T,Td and winds based on latest obs and trends. Upper jet streak moving out of the region with just a few isold showers left that will be weakening over the next few hours. A weak cold front slowly moves across the region tonight. Ahead of the front, an isolated shower cannot be ruled out across interior Lower Hudson Valley. Otherwise, clouds diminish from west to east as the upper jet continues moving offshore. Some uncertainty as to whether or not fog develops early Wednesday morning. The flow is weak and with low level moisture lingering, feel at least patchy fog is a possibility. Low temperatures near seasonable levels in the middle and upper 60s are forecast. A high rip current risk continues this evening for Atlantic ocean beaches as long period swells from distant Hurricane Gert begin to arrive. For the latest information on Gert, please refer to the National Hurricane Center.
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&& .SHORT TERM /6 AM WEDNESDAY MORNING THROUGH WEDNESDAY NIGHT/...
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High pressure will build down from the Great Lakes region on Wednesday as middle and upper level ridging takes shape aloft. Flow will predominately be from the NW, so a drying downslope flow allows dew points to mix out into the upper 50s and lower 60s in the afternoon. Despite forecast soundings showing mixing to 800-850 mb, flow is rather weak and generally 10 kt or less. Have generally sided with the warmer side of guidance, which yields highs in the middle and upper 80s. A few 90 degree readings are possible in NYC metro, but with a relatively weak flow do not think the down sloping will be strong enough for readings to be much higher. Head indices will be held close to ambient temperatures due to lowering dew points in the afternoon. A dry and tranquil night is in store Wednesday night with high pressure in control. Temperatures will be near normal lows, expect across the interior where some upper 50s are likely. A high rip current risk continues into Wed evening for all Atlantic ocean beaches due to long period swells from distant Hurricane Gert.
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&& .LONG TERM /THURSDAY THROUGH TUESDAY/... Weak ridging aloft will keep the area dry through the daylight hours on Thursday as a shortwave trough and associated area of low pressure approach the region from the west. As this low continues to move east Thursday night, the chance of showers will increase as a warm front lifts through the region. With the cold front still well off to the west, the area will reside in the warm sector during the day on Friday. Increasing instability out ahead of the front will result in a chance of thunderstorms Friday and Friday night before the cold front crosses the area on Saturday. With precipitable water values progged to rise above 2 inches, any storms will be capable of producing heavy rainfall. Unsettled conditions continue in the wake of the frontal passage as a second shortwave crosses the region Saturday night into Sunday. This will result in a continued chance of showers and thunderstorms until high pressure begins to build into the region on Sunday. This will usher in a period of drier weather for the beginning of the new work week before another cold front begins to approach the region late in the day on Tuesday. Daytime highs will be near to a few degrees above normal through the period, generally in the low to mid 80s. Overnight lows will run several degrees above normal on Thursday night and Friday as cloud cover and moisture increase ahead of the approaching front, then return to near normal for the weekend into the start of next week. && .AVIATION /22Z TUESDAY THROUGH SUNDAY/...
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A weak cold front moves across late tonight with high pressure building in from the west Wednesday. Mainly MVFR conditions with isold rain showers early this evening. Patchy fog development occurs late tonight into early Wednesday reducing visibilities to MVFR and possibly IFR. There is uncertainty with this so amendments will certainly be possible to refine this timing. Winds less than 10 kt through the period. The wind direction is S-SE through the afternoon, variable tonight, but becoming more west to northwest overnight into daybreak Wednesday. NY Metro Enhanced Aviation Weather Support... Detailed information, including hourly TAF wind component forecasts, can be found at: http:/www.weather.gov/zny/n90 KJFK TAF Comments: IFR will be possible at times through this evening. KLGA TAF Comments: IFR will be possible at times through this evening. KEWR TAF Comments: IFR will be possible at times through this evening. KTEB TAF Comments: IFR will be possible at times through this evening. KHPN TAF Comments: IFR will be possible at times tonight. KISP TAF Comments: IFR will be possible at times tonight. .OUTLOOK FOR 18Z WEDNESDAY THROUGH SUNDAY... .Wednesday-Thursday...VFR. Late day sea breeze possible Wed. Widespread sea breezes Thu afternoon. .Thursday night through Saturday night...MVFR or lower flight cat possible in showers/tstms. .Sunday...VFR.
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&& .MARINE... Long period southerly swells will continue to arrive from distant Hurricane Gert tonight on the ocean waters. The SCA for hazardous seas remains in effect 10pm tonight through 6pm Wednesday. This may need to be extended into Wednesday night on the waters east of Fire Island Inlet. Have elected to hold off until confidence is higher on how quickly the swells will subside late Wednesday. Otherwise, sub-SCA conditions are forecast on the waters through Wednesday night. Swells will continue to subside during the day on Thursday as Gert will be well east of the region. A slow moving frontal system will cross the waters late Thursday through Saturday, but conditions are expected to remain below SCA criteria at this time. && .HYDROLOGY... No hydrologic impacts are anticipated through Thursday night. A slow moving-frontal system may bring periods of heavy rainfall Friday into Saturday. && .OKX WATCHES/WARNINGS/ADVISORIES...
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CT...None. NY...High Rip Current Risk through Wednesday evening for NYZ075-080- 081-178-179. NJ...None. MARINE...Small Craft Advisory for hazardous seas from 10 PM this evening to 6 PM EDT Wednesday for ANZ350-353-355.
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