Area Forecast Discussion
Issued by NWS Upton, NY

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000 FXUS61 KOKX 301043 AFDOKX Area Forecast Discussion National Weather Service New York NY 643 AM 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/... Weak ridging aloft will flatten today as a broad trough east of the Rockies tracks slowly eastward. Clouds will gradually increase today as waa ensues and sfc low pres slowly approaches from the Ohio Valley. Overrunning rain will overspread the area during the mid to late afternoon...but could start moving into NYC and areas west by early afternoon. Soundings are indicating some weak instability with high moisture content through the column...thus embedded tstms with heavy rain is possible...mainly N and W of NYC where the RRQ of a 55-65kt upper jet will be present. && .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 /12Z SATURDAY THROUGH WEDNESDAY/... High pressure briefly builds tonight into the first half of Saturday. Then low pressure slowly approaches from the Ohio Valley. Mainly VFR conditions are expected overnight with increasing mid clouds. Patchy fog development, generally for terminals away from New York metro, is possible overnight. Low probability for VSBY reductions to MVFR or lower in BR. Showers are possible Saturday afternoon, especially west of NYC. Light winds overnight into Saturday morning. Winds become S/SE in the afternoon at 5 to 10 KT. .OUTLOOK FOR 06Z SATURDAY NIGHT THROUGH WEDNESDAY... .Saturday night into Sunday...Chance of showers and possibly a tstm. MVFR or lower conditions possible. .Sunday night-Monday night...Chance of showers. MVFR conditions possible. .Tuesday-Wednesday...Mainly VFR, although isolated showers possible. && .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. && $$

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