Area Forecast Discussion
Issued by NWS Upton, NY

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000 FXUS61 KOKX 211919 AFDOKX Area Forecast Discussion National Weather Service New York NY 319 PM EDT Sat Apr 21 2018 .SYNOPSIS...
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High pressure will be in control through early next week. The high gives way to low pressure mid week. Another low may impact the area late in the week.
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&& .NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
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Quiet and chilly night in store as strong high pressure continues to build into the region from the northwest. The atmosphere remains dry, so clear skies anticipated for the night. Low temperatures will range from the low 30s across the interior and Pine Barrens of Long Island to the upper 30s and lower 40s elsewhere. Some frost is likely to develop where temperatures drop into the low-mid 30s with light winds, so have included frost mention in the grids.
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&& .SHORT TERM /6 AM SUNDAY MORNING THROUGH SUNDAY NIGHT/...
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Tranquil weather will continue Sunday into Sunday night with high pressure in control. Upper trough over southeast Canada moves further to the north and east over the North Atlantic. Heights will gradually rise as an upper ridge over the northern Plains approaches. One last shortwave dives down the back side of the upper trough, which may include a weak surface trough passage in the evening. There will be no discernible change to sensible weather other than a few fair weather clouds in the afternoon and evening. The air mass continues to moderate on Sunday, so temperatures should be several degrees warmer than those on Saturday. Highs will be near seasonable levels in the lower 60s. Good radiational cooling conditions expected Sunday night with temperatures falling into the 30s inland and lower to middle 40s elsewhere.
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&& .LONG TERM /MONDAY THROUGH SATURDAY/...
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Ridge Monday and Tuesday gives way to approaching shortwave that slowly lifts northeast and phases with northern stream shortwave by Wednesday. As this unfolds, sfc low tracks to the east coast, and passes to the northeast Wednesday/Thursday. Rain chances increase during this time, mainly from Tuesday night through Wednesday night. The local area should remain between this departing shortwave, sfc low and downstream shortwave that approaches late in the week, and into next weekend, although timing remains in question. As such, generally dry conditions are expected during this time, with perhaps spotty showers, low coverage. Then higher probabilities for showers are expected Friday night or Saturday, again dependent on timing. As for temperatures, much of the period will feature seasonable temperatures with the exception of Wednesday, where onshore flow will keep highs several degrees below normal.
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&& .AVIATION /19Z SATURDAY THROUGH THURSDAY/... High pressure will build in through the TAF period. VFR. NW-WNW winds around 10 kt with gusts 16-20 kt for most terminals except some coastal terminals at WSW-SW. Overall low confidence regarding which side of 310 magnetic the city terminals prevail. KLGA has a better chance of prevailing north of it, with KEWR and KJFK prevailing south of it. Additionally, KJFK winds could prevail near 310 magnetic through 20-21z instead of the forecast of WSW. A late day/early evening sea breeze is also anticipated for KJFK, but might not occur. .OUTLOOK FOR 18Z SUNDAY THROUGH THURSDAY... .Sunday through Tuesday...VFR. .Tuesday night through Wednesday...MVFR or lower conditions increasingly likely with rain. E winds near 10 kt gusting near 15-20 kt Wednesday. .Thursday...Mostly VFR, chc MVFR in -shra. W gusts around 25 kt. && .MARINE...
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Tranquil conditions continue into early next week on the waters with high pressure in control and a weak pressure gradient. As high pressure builds, then moves east, tranquil conditions are expected across the area waters Monday and Tuesday. Increasing easterly flow ahead of an area of low pressure and warm front should result in building seas Wednesday. Winds will shift as low pressure and frontal boundaries pass Wednesday night and Thursday. Seas should subside some, and Wavewatch III output lowered during this timeframe.
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&& .HYDROLOGY...
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No hydrologic impacts are forecast into early next week. Rain is likely during the mid week period, but no hydrologic issues are anticipated at this time.
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&& .EQUIPMENT... NYC NOAA Weather Radio Station KWO-35 (162.55 MHz) remains off the air. && .OKX WATCHES/WARNINGS/ADVISORIES... CT...None. NY...None. NJ...None. MARINE...None. && $$ SYNOPSIS...DS/PW NEAR TERM...DS SHORT TERM...DS LONG TERM...PW AVIATION...JC MARINE...DS/PW HYDROLOGY...DS/PW EQUIPMENT...

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