Area Forecast Discussion
Issued by NWS Upton, NY

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000 FXUS61 KOKX 301751 AFDOKX Area Forecast Discussion National Weather Service New York NY 151 PM EDT SAT JUL 30 2016 .SYNOPSIS... High pressure moves off the New England coast today as low pressure slowly approaches from the Ohio Valley. This low tracks along a frontal boundary to the south into early next week. An upper level disturbance passes through on Tuesday with high pressure then returning through Friday. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... Regional radar mosaic shows increasing coverage of showers and a few thunderstorms to the west of the area. Sea breeze that is moving across Long Island and southern portions of the NYC metro has also started to develop a few showers along it, mainly from the Western Long Island through near Newark. These sea breeze showers should be brief with better shower/storm development expected by mid afternoon from the city west as better lift with approaching shortwave and increasing warm advection begins to move in. Instability has been on the increase across southern portions of the area with CAPE values ranging from around 750-1200 per latest LAPS. Higher CAPE resides across southern Jersey, and expect this trend to continue into the afternoon. With a moist atmosphere and potential for precip loading with stronger updrafts, an isolated strong wind gusts are possible in heavier showers/storms. Locally heavy rainfall is the main threat today. As the activity translates eastward into this evening, there should be a downward trend in intensity as the precipitation encounters a more stable airmass and the surface high just to the east. Highs will be in the lower to middle 80s. && .SHORT TERM /6 PM THIS EVENING THROUGH MONDAY NIGHT/... As deep layered ridging strengthens across the plains and SW US and a cutoff low pressure system tracks across western Canada...the downstream H5 flow will amplify. Unsettled weather continues through into early next week as the amplifying upper level trough approaches. However...the shortwave and LFQ of jet stream are progged to lift through western New York State late tonight and Sunday. Divergence aloft will pass through western portions of the local area Sun aftn with additional showers and tstms expected. With abundant moisture still present through the column...some storms could produce heavy rainfall. Sfc low pres approaching from the west slowly passes S of Long Island Sunday night through Monday night...followed by the upper trough axis on Tue. Sct showers/tstms remain a possibility with locally heavy rainfall. && .LONG TERM /TUESDAY THROUGH FRIDAY/... Drier weather builds into the area Tuesday through Friday. A few isolated showers will be possible on Tuesday right behind the upper trough. Temperatures remain at or slightly below normal through Tuesday. Then, an increase in heat and humidity start to return. && .AVIATION /18Z SATURDAY THROUGH THURSDAY/...
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SHRA/TSRA developing over NJ and lifting to the east. Activity will become more widespread going into this afternoon, and impacts to KNYC terminals are expected to develop between 19-21Z. Over Long Island, some SHRA/embedded TSRA developed along the sea breeze, and those should taper off in the next hour or so. Expecting SHRA/TSRA for many of the terminals through this evening, and then there should be a lull from around 04-06Z through 08-10Z. SHRA develop again towards Sunday morning, and will persist through the day. Conds will drop to MVFR with local IFR. Persistent onshore, SE flow expected into Sunday. For outlying terminals, winds will go LGT/VRB tonight. .OUTLOOK FOR 18Z SUNDAY THROUGH THURSDAY... .Sunday afternoon...MVFR or lower in SHRA. .Sunday night-Monday Night...Chance of showers and possibly a tstm. MVFR or lower conditions possible. .Tuesday...Mainly VFR, although isolated showers are possible. .Wednesday-Thursday...VFR.
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&& .MARINE... A frontal boundary will remain south of the waters through early next week until low pressure passes to the east Monday night into early Tuesday. This will result in a mainly E/SE flow which will be strongest Sunday afternoon/evening, with possible gusts up to 20 kt on the ocean waters. High pressure will then follow for the mid week. Sub-sca conditions are forecast during the period. && .HYDROLOGY... A large range of rainfall is expected across the area this weekend. Average QPF from this afternoon through Sunday evening is expected to be from around 1/3 of and inch to 1 inch east of NYC and 1 to 1 3/4 inches N and W of NYC. Locally higher amounts are possible in any heavier showers. Minor urban flooding would be the main hydrologic impact in any heavier shower/thunderstorm. && .OKX WATCHES/WARNINGS/ADVISORIES... CT...None. NY...None. NJ...None. MARINE...None. && $$ SYNOPSIS...24 NEAR TERM...24/DS SHORT TERM...24 LONG TERM...24 AVIATION...MPS MARINE...DW HYDROLOGY...24

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