Area Forecast Discussion
Issued by NWS Upton, NY

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000 FXUS61 KOKX 151925 AFDOKX Area Forecast Discussion National Weather Service New York NY 225 PM EST Mon Jan 15 2018 .SYNOPSIS... A high pressure ridge along the East Coast will slowly weaken through tonight. Weak low pressure will then approach from the west on Tuesday, and pass to the north Tuesday night as another low develops off the mid Atlantic coast. This low will deepen and track east of New England on Wednesday. High pressure will then build to the south through Friday, moving into the western Atlantic next weekend. Low pressure will approach from the west on Sunday. && .NEAR TERM /THROUGH TONIGHT/... Only minor updates for this afternoon to reflect current temperature, dew point, and sky trends. Although clouds have cleared out of portions of the lower Hudson Valley, northeast NJ and NYC, expect that with daytime heating the stratocu deck will gradually redevelop across these areas this afternoon. Otherwise, mostly cloudy conditions expected elsewhere. There could be a brief late day window where skies clear briefly except across eastern Long Island/CT, where an upper level jet streak and low level positive theta-e advection should maintain clouds, and may even produce some light freezing drizzle (moisture confined to low levels warmer than -8C as opposed to this morning`s colder environment) or spotty flurries across SE CT and eastern Long Island this evening. Clouds could briefly break again overnight mainly across southern CT and Long Island before lowering and thickening again ahead of the weak low approaching from the west. High temps this afternoon will range from 25-30, warmest toward the metro areas and the coast. Lows tonight expected to be 20-25 in NYC metro and along the immediate coast, with teens elsewhere. && .SHORT TERM /TUESDAY/... The approaching weak low and associated positively-tilted upper trough/deep layer SW flow aloft will approach on Tue, with chances for light snow increasing through the day, especially NW of NYC, where an inch or two of accumulation may be possible by evening. Farther east, low level WAA and light precip intensity at best may not allow temps to cool down as much toward wet bulb temps, so afternoon precip across parts of Long Island more likely to be be a rain/snow mix. High temps should range from the upper 20s well inland, to 30-35 most elsewhere, to some upper 30s in parts of eastern Long Island. && .LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/... Guidance consensus is now rather strong for Tuesday night into Wednesday night for an upper full latitude trough to moves across the eastern United States and into the western Atlantic as the upper flow has become more progressive. The northern stream energy and surface low will be weakening across upstate New York Tuesday night into Wednesday. An inverted trough off the southeast coast Tuesday night develops into a coastal low by 12Z Wednesday off the DELMARVA as the upper trough approaches. Again guidance is well clustered in deepening the low Wednesday, and passing over or near the 70/40 benchmark. Light precipitation, snow, with the weakening low initially moves into the region Tuesday night. Then the coastal low dominates Wednesday into Wednesday night. Low level warm air wraps into the far eastern sections, mainly New London Connecticut to the twin forks of Long Island, ahead of the low late Tuesday night into Wednesday. The ECMWF wraps the warmer air the furtherest west, with the GFS and NAM just across the far eastern zones. Leaned toward this colder solution as the low will be progressive. As such there will likely be a rain/snow mix, and even a change to all rain for a time Wednesday, before colder air returns as the low departs after 21Z Wednesday. Looks to be an advisory level snow event across portions of northeastern New Jersey through the lower Hudson Valley and across southern Connecticut, while coastal locations will be in the 2 inch range. Too early at this time to post an advisory, and also some uncertainty, if the coastal low tracks farther east with the progressive flow, then snow amounts will be lower. Upper flow become zonal Wednesday night into the upcoming weekend. There is a rather weak shortwave that quickly move through the area Friday, however, likely moves through dry with little moisture in place at that time. Surface high pressure builds to the south and moves into the western Atlantic late Sunday into Monday as the next frontal system approaches. && .AVIATION /20Z MONDAY THROUGH SATURDAY/... High pressure north of the region gradually weakens through Tuesday as low pressure approaches from the Great Lakes. NE winds 10 to 15 kt at most locations through this evening. An occasional gust to 20 kt is possible. NE winds weaken overnight and become light and variable away from the city. Winds remain light out of the ENE-E Tuesday morning. BKN-OVC ceilings around 3000 ft to 3500 ft should continue into this evening at most terminals. Lower conditions with ceilings 015-025 are possible at southern Connecticut and Long island terminals. Similar conditions are anticipated tonight with some improvement initially before gradual lowering ceilings to MVFR into Tuesday morning. There is a chance of flurries or light snow into early Tuesday afternoon, but no visibility restrictions are expected at this time. NY Metro Enhanced Aviation Weather Support... Detailed information, including hourly TAF wind component forecasts, can be found at: http:/ KJFK TAF Comments: BKN cigs around 035 into this evening. KLGA TAF Comments: BKN cigs around 035 into this evening. KEWR TAF Comments: SCT-BKN ceilings 035 into this evening may fall to around 030 at times. KTEB TAF Comments: SCT-BKN ceilings 035 into this evening. KHPN TAF Comments: Cigs around 030-035 into this evening. KISP TAF Comments: Cigs around 015-025 into this evening. .OUTLOOK FOR 18Z TUESDAY THROUGH SATURDAY... .Tuesday Afternoon-Wednesday...MVFR Tuesday afternoon falling to IFR in light snow Tues night into Wednesday. Rain/snow mix possible near the coast. .Wednesday night-Thursday...VFR. N-NW winds G20KT. .Friday-Saturday...VFR. && .MARINE... SCA conditions should continue on the ocean waters into tonight, with gusts 25-30 kt today and seas building as high has 7 ft out east. Ocean seas will be at marginal SCA levels Tue into Tue night night with a light southerly flow, and likely continue into Wednesday as low pressure develops off the mid Atlantic coast. This low deepens as passes east of the waters during Wednesday. A strong and gusty northwest flow develops Wednesday and continues into Thursday night. Small craft wind gusts and marginal seas will be likely on the ocean waters Wednesday night into Thursday night with a chance of small craft gusts across eastern Long Island Sound and the eastern Long Island bays. Friday and Friday night winds and seas will be below SCA levels as high pressure builds to the south and a weaker pressure gradient is across the forecast waters. && .HYDROLOGY... No significant hydrologic impacts are expected. && .EQUIPMENT... NYC NOAA Weather Radio Station KWO-35 (162.55 MHz) is off the air for an extended period of time. && .OKX WATCHES/WARNINGS/ADVISORIES... CT...None. NY...None. NJ...None. MARINE...Small Craft Advisory until 6 AM EST Tuesday for ANZ350-353-355. && $$ SYNOPSIS...Goodman/MET NEAR TERM...MD/JE/Goodman SHORT TERM...Goodman LONG TERM...MET AVIATION...DS MARINE...Goodman/MET HYDROLOGY...Goodman/MET EQUIPMENT... is the U.S. government's official web portal to all federal, state and local government web resources and services.