Area Forecast Discussion
Issued by NWS Upton, NY

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000 FXUS61 KOKX 210001 AFDOKX Area Forecast Discussion National Weather Service New York NY 801 PM EDT Sat Apr 20 2024 .SYNOPSIS... A cold front moves offshore early this evening. High pressure then builds in through early next week before giving way to a frontal system on Wednesday. High pressure then builds in through Friday, followed by another frontal system next weekend. && .NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
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Mid and upper level shortwave swings across New England early this evening sending a cold front through the rest of the region. With still enough moisture and a little CAPE and front yet to pass through, have low chance PoPs over parts of eastern LI and SE CT early this evening. Dry weather otherwise as any remaining showers will quickly diminish after sunset with the front offshore and drier air making its way out east. High pressure over the central states begins to build in tonight. Mostly clear skies are expected along with colder and drier air. The boundary layer will initially be mixed before starting to decouple, especially inland, early Sunday morning. Temperatures should fall into the middle 30s inland and upper 30s and lower 40s most elsewhere. There may be some patchy frost for inland areas, but dew points in the 20s should prevent any widespread frost development. Therefore, no Frost Advisory has been issued at this time.
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&& .SHORT TERM /6 AM SUNDAY MORNING THROUGH MONDAY/... High pressure and dry conditions will prevail Sunday through Monday. A large upper level low will settle over southeast Canada on Sunday carving out broad troughing across the eastern US. A southern stream shortwave along the base of the trough will develop a wave of low pressure along the southeast coast through the day. A strong upper jet streak is also expected to lie near New England, which will help to draw up middle and upper level moisture to the north of the low. As a result, increasing clouds will occurs Sunday morning leading to mostly cloudy conditions for the area. Highs will end up below normal in the 50s. The jet streak pushes east Sunday evening allowing the southern low to move out into the Atlantic. Clouds will decrease from northwest to southeast leading to mostly clear skies overnight. Another chilly night is in store with lows in the middle to upper 30s inland and lower 40s closer to the coast. A dry atmosphere will lead to sunny conditions on Monday with highs a bit warmer than Sunday, but still below normal in the lower 60s. && .LONG TERM /MONDAY NIGHT THROUGH SATURDAY/... Zonal flow aloft for Monday night and Tuesday with surface high pressure in control of the weather, keeping us dry through the period. Possibly some patchy frost early Tuesday morning well NW of the city and in the Pine Barrens. High temperatures Tuesday afternoon will be a few degrees below normal. 500mb trough digs towards the Northeast Tuesday night into Wednesday, with a surface low center passing to our north. Shower chances begin late at night, then showers become likely on Wednesday with the passage of an associated cold front. High pressure then begins to build back in behind the storm system Thursday night and remains in control through Friday. Dry during this time, and high temperatures both days will be a few degrees below normal. Models differ on the timing of the next low pressure system, which could impact the weather next weekend. They at least agree that a surface low heading into the Great Lakes will run into mid- level ridging. This will help weaken the system and keep its center to our north this weekend, with the best chance of showers arriving with the leading warm front and trailing cold front. Will go with a chance of showers starting mainly Saturday afternoon, but we might be able to get through the daytime hours of Saturday without seeing any showers. High temperatures remaining a few degrees below normal. && .AVIATION /00Z SUNDAY THROUGH THURSDAY/...
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A cold front will pass through the eastern terminals within the hour. Brief MVFR conditions possible at KGON in a shower along with gusts up to 30kt, otherwise VFR at all terminals through the period. Winds become NW at all terminals in the hour with gusts of 20-25kt, possibly up to 30 kt. Gusty winds end anywhere from 03Z to 05Z, then become WNW at less than 10 kt. On Sunday, winds back to the W increasing 10-15kt G15-20kt. Coastal locations may back to the WSW if not SW. Confidence in a true seabreeze is low due to the strength of the westerly winds in the mixed layer. ...NY Metro (KEWR/KLGA/KJFK/KTEB) TAF Uncertainty... A few gusts up to 30 kt this evening. Gusts may be more occasional on Sunday. OUTLOOK FOR 00Z MONDAY THROUGH THURSDAY... Sunday Night-Tuesday: VFR. Wednesday: MVFR or lower with showers. S winds 10-15G20-25kt in the afternoon/evening, becoming NW at night. Thursday: VFR. Gusty NW flow. Detailed information, including hourly TAF wind component forecasts, can be found at: https:/www.weather.gov/zny/n90
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&& .MARINE...
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A cold front moves across the waters this evening. There may be a few gusts close to 25 kt, especially on the NY Harbor, western Sound and western Ocean with the passage of the front. Otherwise, winds and seas will remain below SCA levels. High pressure will otherwise build tonight through Monday. Winds and seas are expected to remain below SCA levels given the relatively weak pressure gradient. High pressure should keep conditions at sub-advisory levels through at least Tuesday morning, then gusts to 25 kt could be possible on the ocean waters west of Fire Island Inlet in the afternoon. The pressure gradient tightens with slowly increasing winds Tuesday night into Wednesday, increasing the likelihood of SCA conditions across all ocean waters during this period. Seas on a southerly flow build up to around 5 ft on Wednesday. A cold front then passes through, and SCA conds will still be likely on the ocean Wednesday night. Offshore winds diminish on Thursday along with subsiding seas. Sub-advisory conditions are therefore anticipated by the end of the day.
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&& .HYDROLOGY... No hydrologic impacts expected through next week. && .OKX WATCHES/WARNINGS/ADVISORIES... CT...None. NY...None. NJ...None. MARINE...None. && $$ AVIATION UPDATE...DW

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