Area Forecast Discussion
Issued by NWS Upton, NY

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000 FXUS61 KOKX 141645 AFDOKX Area Forecast Discussion National Weather Service New York NY 1145 AM EST Sat Jan 14 2017 .SYNOPSIS...
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High pressure passes offshore this afternoon with a weak wave of low pressure passing well to the south tonight. High pressure builds over the region Sunday into Monday, then moves off the Mid Atlantic and northeast coast Monday night and Tuesday as a frontal system approaches to the west. A warm front moves through the region Tuesday followed by a cold front Wednesday. High pressure builds in Wednesday night through Thursday and moves offshore through Friday.
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&& .NEAR TERM /UNTIL 6 PM THIS EVENING/...
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Mid and high clouds will continue to increase ahead of a frontal system that will pass to the south. Some light snow may impact southern and western portions of the area late this afternoon, assuming sufficient low level saturation occurs. Much of this reliant on available lift, and approach of upper jet. Best chance will be closer to the coast. Temperatures will remain nearly steady, and may fall a few degrees in areas where snow occurs.
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&& .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM SUNDAY/...
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Water vapor imagery shows a short wave moving towards New England. Stronger northwest flow as the wave moves east should help to keep the developing low more to our south. Despite weak warm advection in the low levels, dry air and subsidence will inhibit much more than light snow with minimal accumulations. However, NWP model suite continues to suggest light precip does indeed develop, with low QPF amounts from a trace to a few hundredths of an inch. If precip does develop, boundary layer will cool, and wet bulb temps will remain below freezing. As such, any precip will be in the form of snow this evening. Temperatures tonight will be close to climatological normals. Dry conditions follow for Sunday as high pressure builds eastward again.
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&& .LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/... Weak upper ridging builds ahead of an approaching southern stream shortwave Sunday night into Monday night that will get picked up in the eastern portion of a northern stream shortwave Monday night into Tuesday across the northern plains into the upper midwest. Surface high pressure builds over the area Sunday night into Monday. A wide range in overnight lows Sunday night are expected with ideal radiational cooling conditions. A return flow develops Monday as the high begins to shift offshore. Warmer air will be moving into the region as a warm front develops ahead of surface low pressure. The front across the region will be weak with weak frontal forcing. Systems have slowed, with the ECMWF slower than the GFS. Light precipitation develops with the front right around 12Z Tuesday. Still expecting a brief period of wintry weather Tuesday morning with the onset of precipitation. There is still uncertainty with the areal extent of the wintry mix and will be dependent on how quickly the surface cold air is scoured out. Model soundings do indicate mostly liquid even well inland at the beginning of the precipitation. During Tuesday morning the warm front moves through and by late morning all liquid precipitation is expected. With the slower progression of the upper trough, which becomes negative Tuesday night into Wednesday, precipitation continues until the cold frontal passage Wednesday. Models have trended drier for Wednesday night through Friday. There is no really cold air behind the front with warming setting up for Friday. && .AVIATION /18Z SATURDAY THROUGH THURSDAY/... High pressure will build to our north, allowing winds to shift from the northeast to a more southerly direction in the afternoon. Winds will remain light. Light snow will be possible late this afternoon-evening as a low pressure system passes to the south, with the best chance across southern terminals. .OUTLOOK FOR 12Z SUNDAY THROUGH WEDNESDAY... .Sunday...VFR. .Monday...VFR. .Monday night-Tuesday...MVFR or lower possible in rain near the coast, and wintry mix inland. .Wednesday...MVFR or lower possible in rain. && .MARINE...
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Winds and seas forecast on track. Light flow this afternoon expected, with tranquil seas. Sub-SCA conditions are forecast through tonight. NW winds develop late tonight behind low pressure well to the south and east. Gusts on the ocean waters could get up to 20 kt by daybreak Sunday. Winds and seas will remain below small craft levels from Sunday night through Monday night as high pressure builds into the waters, then moves east Monday night. An increasing, and prolonged, southerly flow will develop Tuesday around the departing high and an approach frontal system. By Wednesday, just before a clod frontal passage, ocean seas are expected to be at small craft levels. In addition southerly gusts will be around small craft levels for a short period of time, then diminish briefly as the cold front moves across the waters. A gusty westerly flow behind the front will then increase with small craft conditions expected once again. Small craft winds and seas will continue into Thursday morning. The remainder of the forecast waters are expected to remain below advisory levels Tuesday through Thursday.
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&& .HYDROLOGY... No significant precipitation is forecast this weekend into next week. No hydrologic impacts are expected. && .OKX WATCHES/WARNINGS/ADVISORIES... CT...None. NY...None. NJ...None. MARINE...None. && $$ SYNOPSIS...MD/MET NEAR TERM...PW SHORT TERM...MD/PW LONG TERM...MET AVIATION...JMC/MD MARINE...MD/MET/PW HYDROLOGY...JC/DW

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