Area Forecast Discussion
Issued by NWS Upton, NY

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000 FXUS61 KOKX 130914 AFDOKX Area Forecast Discussion National Weather Service New York NY 414 AM EST Wed Dec 13 2017 .SYNOPSIS...
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High pressure builds across the area today. A low pressure system tracks south of the area late tonight then moves offshore Thursday. High pressure briefly builds over the region Thursday through Friday. Low pressure passes southeast of the region Friday night into Saturday, followed by a second wave of low pressure late Sunday and Monday. High pressure briefly builds over the region Monday night, followed by another chance of unsettled weather for mid-week.
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&& .NEAR TERM /UNTIL 6 PM THIS EVENING/...
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Dry, cold and windy conditions expected today as High pressure builds into the area. Highs today will be in the upper 20s to lower 30s. Wind gusts will remain just below advisory levels through much of the day with wind gusts of up to 40 mph. This will make temperatures feel colder with wind chills in the teens to around 20.
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&& .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM THURSDAY/...
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Winds are forecast to diminish tonight, as high pressure moves across the area. Temperatures tonight will be in the upper teens to low to mid 20s. A clipper will then approach late tonight from the Ohio Valley, tracking just south of Long Island through Thursday. There will be enough cold air in place to support an all snow event from late tonight into early Thursday morning. Precipitation amounts will be light with mainly less than an inch expected. High temperatures on Thursday will be in the upper 20s to mid 30s. Precipitation is expected to end by Thursday afternoon as the clipper moves further offshore.
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&& .LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/...
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The long term period starts off with weak high pressure over the region Thursday night into Friday. 13/00z forecast guidance indicating a shortwave/upper level low diving out of Canada and moving over the region Friday night into Saturday. As it does, a surface low develops, passing well offshore. Thinking at this point, that most of the region stays dry, but can not rule out a slight chance of some snowflakes across the twin forks of LI and eastern CT. Weak high pressure and ridging then briefly builds back over the region Saturday night into Sunday, allowing temperatures to rebound a bit back to more seasonable levels. Another weak wave of low pressure slides across region late Sunday through Monday. Both the ECMWF and GFS capture this system, however the ECMWF is a bit more robust with its precipitation. Also, there are some slight timing issues with just how quickly the system moves into and out of the region. With the warmer temperatures in place, do expect precipitation to be either rain or a rain/snow mix along the coast, with temperatures cold enough for some light snow inland. Temperatures do warm enough on Monday for precipitation to become rain everywhere. Dry conditions then expected Monday night into the first part of Tuesday. Additional light precipitation is then possible Tuesday afternoon into Tuesday night as another shortwave slides across the region. A few left over rain or snow showers will be possible on Wednesday, however for now will keep conditions dry as weak high pressure starts to build southwest of the region.
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&& .AVIATION /09Z WEDNESDAY THROUGH SUNDAY/...
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VFR today as low pressure pulls into the Canadian Maritimes. MVFR conditions or lower are possible tonight in snow as another area of low pressure approaches from the west, generally after 05Z. Less than an inch of accumulations is possible during this time frame. As for winds, W winds of 20 to 25 kt true, with gusts near to slightly above 35 kt. There could be some occasional gusts of 40 kt or slightly higher. Best timing for the strongest gusts is 13Z to 21Z. Thereafter, gusts should slowly diminish through the rest of the TAF period. ...NY Metro Enhanced Aviation Weather Support... Detailed information, including hourly TAF wind component fcsts, can be found at: http://www.weather.gov/zny/n90 KJFK TAF Comments: Occasional gusts of 40 kt or slightly higher possible, mainly from 13Z-21Z. The afternoon KJFK haze potential forecast is GREEN, which implies slant range visibility 7SM or greater outside of cloud. KLGA TAF Comments: Occasional gusts of 40 kt or slightly higher possible, mainly from 13Z-21Z. The afternoon KLGA haze potential forecast is GREEN, which implies slant range visibility 7SM or greater outside of cloud. KEWR TAF Comments: Occasional gusts to 40 kt possible, mainly from 13Z- 21Z. The afternoon KEWR haze potential forecast is GREEN, which implies slant range visibility 7SM or greater outside of cloud. KTEB TAF Comments: Occasional gusts to 40 kt possible, mainly from 13Z- 21Z. KHPN TAF Comments: Occasional gusts to 40 kt possible, mainly from 13Z-21Z. KISP TAF Comments: Occasional gusts of 40 kt or slightly higher possible, mainly from 13Z-21Z. .OUTLOOK FOR 06Z THURSDAY THROUGH SUNDAY... .Wednesday night-Thursday morning...MVFR/IFR in snow, mainly overnight Wednesday night through early Thursday morning. W winds 15-20 kt G25-30 kt Wednesday evening. W winds diminish overnight Wednesday. .Thursday afternoon-Friday...Mainly VFR. NW wind G15-20kt into early Thursday night, diminishing thereafter. .Friday night...VFR .Saturday-Saturday night...VFR. NW winds G20-25kt during day, G15-20KT during evening. .Sunday...MVFR or lower possible in rain/snow.
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&& .MARINE...
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Gale warning continues across all waters through tonight, with NY Harbor, Western LI Sound and the South Shore Bays falling below gales by this evening. Small craft advisory conditions are then expected tonight as the next system approaches. Some leftover 5-6 ft seas continue Thursday night on portions of the ocean waters, then conditions fall below SCA levels Friday morning. Low pressure, well south and east of the region intensifies Friday night into Saturday as it moves northeast off the coastal waters. Tightening pressure gradient and building seas will most likely yield Small Craft Advisories, with possible Gales for the ocean waters late Friday night and Saturday. Winds and seas then fall below SCA levels on Sunday. A series of weak wave of low pressure move across the area waters Monday-Wednesday of next week. As each of these systems moves across the area waters, Wind and seas may increase to SCA levels.
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&& .HYDROLOGY... No significant hydrologic impacts 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...
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CT...None. NY...None. NJ...None. MARINE...Small Craft Advisory until 6 AM EST early this morning for ANZ330-335-338-340-345. Gale Warning until 6 PM EST this evening for ANZ335-338-345. Gale Warning until 6 AM EST Thursday for ANZ330-340. Gale Warning until 6 AM EST Thursday for ANZ350-353-355.
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&& $$

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