Area Forecast Discussion
Issued by NWS Upton, NY

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000 FXUS61 KOKX 201149 AFDOKX Area Forecast Discussion National Weather Service New York NY 749 AM EDT Sat May 20 2017 .SYNOPSIS... High pressure builds this morning, then moves east late today and tonight. A series of frontal systems impact the area next week. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... Mosaic radar shows scattered showers upstream, with most activity in upstate NY not reaching the ground. Based on latest high resolution model and 00Z NWP suite, expect plenty of clouds today, along with spotty showers/sprinkles. Best chance for showers, associated with mid level convergence, would be from around NYC metro and points west, but cannot rule out some of this activity making some eastward progress. As the ridge builds to the west and steering flow turns toward the SE, any activity passes south and east by afternoon. Gusty NE winds turn to the E/SE and lighten as the high builds from the north. What a difference in temperatures, with highs only in the 60s. Much lower dew points as well. && .SHORT TERM /6 PM THIS EVENING THROUGH SUNDAY NIGHT/... Upper ridge builds temporarily, as sfc high passes offshore during this time frame. Generally clear skies tonight into Sunday morning will give way to increasing high and mid clouds later in the day Sunday. Cool temps tonight, ranging from around 40 in the normally cooler locations, to around 50, will warm into the 60s Sunday, still below normal. By Sunday night, the ridge axis moves east, and deep SW flow, and WAA moves in. Showers will become increasingly likely as the night progresses. A warm front approaches, with the cold front lagging back into PA by early Monday morning. Sfc low will remain north of the Great Lakes, associated with closed upper level low. && .LONG TERM /MONDAY THROUGH FRIDAY/... A broad upper trough over the mid section of the country translates slowly east through the week. This will result in multiple frontal systems impacting the area this week, the first Monday into Monday night, and then another Wednesday night into Thursday. Both have the potential for widespread showers/isolated thunderstorms and rainfall amounts in excess of an inch. Global models, in particular the GFS and ECMWF, are in overall good agreement with a gradual eastward translation of a high amplified flow across the conus. There are of course some timing differences, but they are not that significant for this point in time. Temperatures Monday will be several degrees below seasonable, in particular Monday, with onshore flow and widespread rain. The rest of the week will moderate to near or slightly above seasonable levels. && .AVIATION /12Z SATURDAY THROUGH WEDNESDAY/...
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VFR as high pressure builds through tonight. NE flow 10-15g20-25kt this morning expected to diminish 15z- 17z as pressure gradient relaxes with high pres builds from the north. Area of showers over eastern PA starting to track ewd and expect them to move into metro terminals 14-15z. Based on steering flow ISP should also be impacted by these showers as well. Less confidence in showers reaching KBDR as they should take a turn to the ESE as they move through the city so will keep VCSH for now. Even lower confidence at KGON. Activity should come to an end between 18z and 20z. Intensity will be light. Elsewhere...area of showers impacting KSWF should move out by 15z and don`t expect the PA activity to make it in there. Winds will veer to the E and SE this afternoon while decreasing in speed. Winds at KJFK/KISP/KBDR/KGON could be 10-20 degrees more to the south aft 18Z...if seabreeze develops. Land/sea temp/density differential may not be enough though. Winds lighten even further this eve. .OUTLOOK FOR 12Z SUNDAY THROUGH WEDNESDAY... .SUNDAY...VFR. .SUNDAY NIGHT-MONDAY...MVFR or lower conditions in showers. Slight chance of thunderstorms on Monday. .TUESDAY...VFR. .WEDNESDAY...Mainly VFR, chance of late day showers, slight chance of thunderstorms.
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&& .MARINE... Posted SCA for the ocean waters for this morning earlier. Gusty NE winds initially will diminish this afternoon as high pressure builds from the north and winds shift to the E/SE. These lighter winds persist through the latter portion of the weekend as the high slowly pushes offshore. Increasing southerly flow is expected Sunday night and Monday ahead of a cold front. Conditions may approach SCA criteria as winds increase, and ocean seas build to 4 or 5 ft. Then, expect winds to diminish and seas to remains fairly tranquil, or subside somewhat as high pressure builds across the waters Tuesday into Wednesday. && .HYDROLOGY... Do not foresee hydrologic impacts Monday, but cannot rule out poor drainage/urban flooding if 1 to 2 inch amounts are realized. && .OKX WATCHES/WARNINGS/ADVISORIES... CT...None. NY...None. NJ...None. MARINE...Small Craft Advisory until 1 PM EDT this afternoon for ANZ350- 353-355. && $$ SYNOPSIS...PW NEAR TERM...PW SHORT TERM...PW LONG TERM...DW/PW AVIATION...24 MARINE...PW HYDROLOGY...PW is the U.S. government's official web portal to all federal, state and local government web resources and services.