Area Forecast Discussion
Issued by NWS Upton, NY

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000 FXUS61 KOKX 130221 AFDOKX Area Forecast Discussion National Weather Service New York NY 921 PM EST Wed Dec 12 2018 .SYNOPSIS... High pressure builds in from the north tonight, then shifts offshore in advance of a weak coastal low into Thursday night. An area of low pressure will impact the region by this weekend. High pressure builds early next week. && .NEAR TERM /THROUGH THURSDAY/... Near normal temperatures expected tonight, despite Arctic high pressure building in from the north. Although the ongoing stratocumulus across western portions of the forecast area may eventually dissipate with the loss of diurnal heating, thicker mid and upper level clouds are moving into the area ahead of an approaching low pressure system, which will likely moderate the potential loss of heat overnight. Additionally, by late night, weak warm advection will begin to occur as the high shifts more offshore. Although it will take some time for the antecedent dry air mass to recover, it is possible in a weak warm advection regime that a few snow flakes may fall prior to sunrise, particularly across western portions of NJ and the lower Hudson Valley. Expect lows in the 20s to lower 30s. && .SHORT TERM /THURSDAY NIGHT/...
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Forecast updated based on 18z operational models and high-res models, potential has increased for 1 to 2 tenths of an inch qpf across western portions of the local Tri- State area Thursday morning into Thursday afternoon. The strongest forcing for ascent will occur Thursday morning into afternoon as vigorous upper low approaches and then moves through the area. Low level warm advection via a developing 20-25kt S/SE llj will allow for gradual moisture return Thursday morning. The timing of precip onset will be critical for snow accum potential across the coast. Model forecasts have continued cold enough with temp profiles for all snow across the interior, and a transition from snow to rain Thu morning along the coast. This scenario poses a moderate to high potential for a light accumulating snowfall across interior portions of northeastern New Jersey, the Lower Hudson Valley, and Southwestern Connecticut Thursday morning into afternoon. 1 to 2 inches of snowfall is likely in this area. There is a low potential for locally 2 to 4 inches of snow, mainly across the hills terrain. Hazardous travel conditions are likely Thursday morning into afternoon in this area. Along the coast, including the NYC/NJ metro, light snow Thursday morning will transition to rain from southeast to northwest later Thursday morning into early afternoon, with a low to moderate potential for a light snow accumulation before changeover to rain. A dusting to around an inch of snow is likely before a changeover to rain for the NYC/NJ metro and northwestern Long Island. A reasonable worst case scenario would be a 1 to 2 inch accumulation across northern portions of NYC and NW LI. Meanwhile, eastern Long Island and southeastern Connecticut may see little to no snow accumulation due to the temps profile warming before any precip develops. Timing and location of heaviest precip, timing of onset of snowfall, and timing of changeover from snow to rain are still a bit uncertain. This makes for an overall low to moderate confidence snowfall forecast at this time. If precip is slow to develop, the potential for accumulating snow will decrease along the coast. Increasing clarity will likely not be until late tonight into early Thursday morning as precipitation begins to develop into the region. Temperatures will rise above freezing along the coast in the late morning into early afternoon with onshore flow, while temps will likely remain at or just below freezing across the interior. There is potential for freezing drizzle late day into evening across interior as mid- levels dry, but low- level E/SE flow continues. These conditions will continue into the night, with temperatures slightly above normal in cloudy conditions and onshore flow.
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&& .LONG TERM /FRIDAY THROUGH WEDNESDAY/... An area of low pressure will track across the southern states and into the Mid Atlantic by this weekend. Rain will spread across the area Friday night and through Saturday and possibly lingering into Sunday morning. An upper level wave drops through the area Sunday night and into Monday, resulting in showers across the area and possibly snow showers across inland locations. Dry weather returns as high builds in on Tuesday and remains through the middle of the week. Temperatures will be above normal on Friday and Saturday ahead of the low pressure system, with highs in the upper 40s to lower 50s. Temperatures fall back to near to slightly below normal Sunday and through the remainder of the long term period. && .AVIATION /01Z THURSDAY THROUGH MONDAY/...
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High pressure moves east tonight. A weak disturbance moves across the area on Thursday. VFR tonight with increasing mid and high clouds. MVFR to possibly IFR conditions develop in the morning with light snow or flurries for the NYC and Lower Hudson Terminals. Drier air across eastern CT and Long Island may impede the eastward progression until late morning/early afternoon. Coastal locations are likely to see a quick changeover to rain. Light and variable winds become E/NE less than 10 kt overnight. Easterly winds 10-15KT at the coast on Thursday and 5KT or less in the interior. .OUTLOOK FOR 00Z FRIDAY THROUGH MONDAY... .Thursday NIGHT...MVFR/IFR with possible -FZDZ at KSWF. .Friday...MVFR to start, then MVFR/IFR conditions late in rain. .Saturday...IFR likely in rain. .Sunday and Monday...MVFR possible in a chance of rain.
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&& .MARINE... Winds and seas will remain below SCA levels through Friday as high pressure builds from the north and then shifts offshore ahead of a weak low pressure system. As a frontal system approaches the area waters Friday night and into Saturday, SCA conditions may be needed as winds and seas increase. SCA level conditions remain Sunday and possibly through the middle of the week. && .HYDROLOGY... No significant widespread liquid equivalent amounts expected through Friday. Rainfall amounts Friday night into Saturday will range from 0.5 to 1 inch across the region. This could result in minor flooding in poor drainage areas, otherwise the recent dry conditions should limit any flooding potential. && .EQUIPMENT... NYC Central Park winds are out of service until further notice. Loss of data is due to a severed cable. Parts are on order. NYC NOAA Weather Radio Station KWO35 (162.55 MHz) will remain off the air for an extended period of time. && .OKX WATCHES/WARNINGS/ADVISORIES... CT...None. NY...None. NJ...None. MARINE...None. && $$ SYNOPSIS...MD/Fig NEAR TERM...MD/NV SHORT TERM...MD LONG TERM...Fig AVIATION...DW MARINE...MD/Fig/NV HYDROLOGY...MD/Fig EQUIPMENT...//

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