Area Forecast Discussion
Issued by NWS Upton, NY

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000 FXUS61 KOKX 210236 AFDOKX Area Forecast Discussion National Weather Service New York NY 1036 PM EDT Thu Sep 20 2018 .SYNOPSIS... High pressure remains over the region overnight, then weakens and slides east on Friday. A cold front will approach Friday afternoon and move across the area Friday night into Saturday morning. Strong high pressure builds to the north of the area this weekend and then offshore early next week. A frontal system will then impact the area Tuesday into Wednesday, ending with a cold frontal passage Wednesday night. High pressure follows for Thursday. && .NEAR TERM /UNTIL 6 AM FRIDAY MORNING/... Increased cloud coverage, to overcast, overnight as low levels remain nearly saturated on 00Z OKX sounding and BUFKIT soundings and a strong subsidence inversion was in place. A few sprinkles were seen at KHVN and eastern LI Sound. Will add slight chance probability for the overnight. Otherwise only minor additional adjustments to the temperatures and dew points. Overnight lows were not adjusted as lows look ok. A warm front develops to the north of the region overnight into early Friday morning. Used a MAV/MET/ECS blend for temperatures. && .SHORT TERM /6 AM FRIDAY MORNING THROUGH FRIDAY NIGHT/... High pressure over the region slide east through the day Friday, as a cold front moves towards the region, eventually passing through the area late Friday night into Saturday morning. Skies should remain mostly cloudy into Friday afternoon, especially well north and west of NYC in advance of the cold front as moisture remains trapped beneath a low level inversion. Further east, skies may become partly cloudy by afternoon. Gusts Friday afternoon could reach 25-30 mph. Highs on Friday should reach the lower and middle 70s. Friday late afternoon through Friday night, the cold front moves across the area accompanied by showers and a chance of thunderstorms. Forecast models showing any convective line that develops Friday afternoon, should weaken as it approaches and moves across the local area as it reaches a more stable environment during the late evening and overnight hours. CAPE and stability will be elevated, as low levels are capped. Lows Friday night will drop into the 60s. There is a moderate risk for the development of rip currents at the Atlantic ocean beaches of New York City, Nassau county, and southwestern Suffolk, and a high risk at the southeastern Suffolk Atlantic beaches Friday. && .LONG TERM /SATURDAY THROUGH THURSDAY/... On the heels of a cold frontal passage early Saturday morning, a progressive, confluent upper flow across the northeast quarter of the nation will allow for strong high pressure to build to the north of the area this weekend. Temperatures will drop to or just below seasonable levels during this period. There could be some high clouds Saturday night into the first half of Sunday as a frontal wave passes to the south of the area. There is also slight chance of light rain in the waters south of Long Island. This feature will have to be watched if the upper flow amplifies a bit more with a passing shortwave. However, would not expect much more than a possible sprinkle across Long Island and the NYC metro. The weather then takes a downhill swing for the midweek as an upper trough out west races eastward with a frontal system impacting the area Tuesday into Wednesday. First of which will be with overrunning showers Monday night into Tuesday night and then with scattered convection on Wednesday. The cold front follows Wednesday night. There are some small timing issues with the global models as can be expected at this juncture in time. It briefly gets warm and humid Wednesday in the warm sector, but quickly back to seasonable levels to end the week. && .AVIATION /03Z FRIDAY THROUGH TUESDAY/...
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High pressure remains over the Northeast this evening, then shifts offshore Friday. A cold front approaches late Friday night. VFR this evening, with cigs lowering to MVFR overnight. SE winds under 10 kt. For Friday, improvement to VFR in the aftn, and also a chance for showers and thunderstorms, mainly after 18Z. However, the chances are too low to include in the TAFs at this time. Best chances are for N and W of the city terminals, such as KSWF. Lower cigs and vsby are possible if a shower or thunderstorm does move through on Friday. Afternoon S gusts mostly around 25 kt. .OUTLOOK FOR 00Z SATURDAY THROUGH MONDAY... .Friday night...VFR during the day, then a chance of showers and thunderstorms with MVFR at night. .Saturday-Sunday...An early shower Saturday, then VFR through the weekend. .Monday...VFR. .Tuesday...MVFR or lower in showers.
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&& .MARINE... Seas running a around 1 foot lower across the eastern ocean waters, around 3 feet, so lowered through the overnight with a light easterly flow. Otherwise no other changes. Winds and seas remain below small craft levels overnight as high pressure remains over the waters. This high slides east on Friday, resulting in an increasing S-SW flow ahead of an approaching cold front. SCA conditions are expected to develop on the area waters Fri night, with wind gusts to 25 kt and ocean seas around 6 ft. There is a chance the SCA conditions develop a few hours earlier than forecast. Winds should diminish by Sat morning, although SCA swells on the ocean will likely linger into Saturday morning. Sub-SCA conditions are then expected on all waters through the remainder of the weekend as high pressure builds to the north. Easterly winds likely strengthen Monday into Monday night and continue into Tuesday ahead of an approaching warm front. SCA conditions are likely to develop during this time. && .HYDROLOGY... No significant hydrologic impacts expected through Tuesday. There is potential for rounds of heavy showers and thunderstorms mid week with a frontal system. && .EQUIPMENT... NYC NOAA Weather Radio Station KWO-35 (162.55 MHz) remains off the air for an extended period of time. && .OKX WATCHES/WARNINGS/ADVISORIES... CT...None. NY...High Rip Current Risk from 7 AM EDT Friday through Friday evening for NYZ081. NJ...None. MARINE...Small Craft Advisory from 6 PM Friday to 6 AM EDT Saturday for ANZ330-335-338-340-345-350-353-355. && $$ SYNOPSIS...BC/DW NEAR TERM...BC/19 SHORT TERM...BC LONG TERM...DW AVIATION...JC MARINE...BC/19/DW HYDROLOGY...BC/DW EQUIPMENT...

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