Area Forecast Discussion
Issued by NWS Upton, NY

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477 FXUS61 KOKX 262011 AFDOKX Area Forecast Discussion National Weather Service New York NY 411 PM EDT TUE JUL 26 2016 .SYNOPSIS...
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A weak front will move across this evening. High pressure will build from the west on Wednesday, and move east by Thursday. A weak cold front will approach the region Thursday Night, and remain in the vicinity as a few waves of low pressure pass nearby into the weekend. High pressure builds back in for early next week.
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&& .NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/...
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Weak sfc trough will remain in place late this afternoon, while mainly NW flow will continue to gust to 15-20 kt. Expect sct Cu mainly over NYC metro and the interior to dissipate this evening, and high clouds over NYC metro and Long Island to pass east. Then a weak front to the NW should pass through this evening after loss of daytime heating, with winds becoming light northerly. Sided with the cool end of guidance for lows tonight, with a wide range of temps, from the 70s invof NYC, to the 60s most elsewhere, to some upper 50s in some interior valleys. Rip current risk remains moderate as primary southerly swells increase to 3 ft with a 6-7" period, along with a secondary residual long period 1-ft SE swell.
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&& .SHORT TERM /6 AM WEDNESDAY MORNING THROUGH WEDNESDAY NIGHT/... Models continue to agree on the region lying between a closed low over Quebec and flat SE US ridging, with zonal flow aloft. At the surface, high pressure will give way to weak thermal troughing developing in the afternoon. Hot conditions will continue, with highs 90-95, near or slightly above the warmest MOS guidance. Dewpoints in the upper 50s and lower 60s will keep heat index values at or just below ambient temperatures, so do not plan to extend the heat advisory for NYC. Temps Wed night will be similar to those forecast for tonight, will perhaps a little more widespread upper 50s across the interior. && .LONG TERM /THURSDAY THROUGH TUESDAY/...
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Models are in general agreement with the H5 pattern across North America through the long term. A cutoff low over Northern Quebec Thu morning will be slow to move NE through Friday keeping a broad trough across the NE quarter of the US. As the cutoff lifts into the Maritimes heights will slowly begin to rise as a deep anticyclone reestablishes itself over the Central US. Somewhat of a complex scenario at the sfc during the first half of the period. A cold front approaches from the west as a wave of low pressure ejects out of the mid-Mississippi valley Thu/Thu night. 12z NWP guidance have come into better agreement that this low will impact the area on Fri into Fri night. However...there are still differences with timing...track and strength that need to be resolved. Have increased pops to likely on Fri since there is better agreement amongst the guidance. Instability not very impressive...although there could be some rumbles of thunder. There is also the potential for locally heavy rain with PW`s forecasted to be in excess of 2 inches. Once the wave moves by there should be a lull on Sat although with the front remaining close to the area have kept schc pops. Another wave may impact the area Sat night into Sun...although the long range models diverge at this point. Have kept low chc pops for now...but it could end up being mostly dry if the wave doesn`t materialize. The boundary is finally nudged southward early next week as high pressure builds in from Canada. One final day with 90 degree temps Thu...then highs will be closer to normal levels into early next week.
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&& .AVIATION /20Z TUESDAY THROUGH SUNDAY/... High pressure builds east from the Ohio Valley through tonight. Forecast challenge this afternoon is whether or not a seabreeze impacts the coastal terminals. May see brief winds shifts where the seabreeze moves in and then out. Preference at this time is to only mention seabreeze at KGON where the flow is weaker. The W/NW flow looks to be strong enough to prevail most of the time elsewhere. Winds generally 280-300 through this afternoon at 10 to 15 KT G20 KT. Winds become N early this evening and lower to less than 10 KT. LGT/VRB winds likely after midnight tonight. Winds veer around to the W/SW Wed afternoon with seabreezes at the coastal terminals as early as 14Z. ...NY Metro Enhanced Aviation Weather Support... Detailed information, including hourly TAF wind component forecasts, can be found at: http:/www.weather.gov/zny/n90 KJFK TAF Comments: Winds may vary by 20 degrees with the close proximity of a trough. Low chance of an afternoon seabreeze, KLGA TAF Comments: Winds may vary by 20 degrees with the close proximity of a trough. Gusts may be a few KT higher than forecast this afternoon. KEWR TAF Comments: Winds may vary by 20 degrees with the close proximity of a trough. Gusts may be a few KT higher than forecast this afternoon. KTEB TAF Comments: Winds may vary by 20 degrees with the close proximity of trough. KHPN TAF Comments: No unscheduled AMDs expected. KISP TAF Comments: Low chance of a late day seabreeze. .OUTLOOK FOR 18Z WEDNESDAY THROUGH SUNDAY... .Wednesday Afternoon-Thursday...VFR. Isolated showers and thunderstorms possible Thursday afternoon, mainly NW of the NYC terminals. .Thursday Night-Sunday...MVFR or lower possible with a chance of showers and thunderstorms. The best chance looks to be on Friday. && .MARINE...
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Sub-SCA conditions will prevail through Wed night. There is a low chance of SCA conds on the waters Fri depending on the track and strength of low pressure passing near the area. Otherwise...sub-advsy conds are expected through the rest of the period.
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&& .HYDROLOGY...
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There is potential for significant rainfall from late Thursday night into Friday night. Locally heavy rainfall is possible...which may cause flooding concerns although it is still too early for specifics.
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&& .OKX WATCHES/WARNINGS/ADVISORIES... CT...None. NY...Heat Advisory until 6 PM EDT this evening for NYZ072>075-176- 178. NJ...None. MARINE...None. && $$ SYNOPSIS...Goodman/24 NEAR TERM...Goodman SHORT TERM...Goodman LONG TERM...24 AVIATION...DW MARINE...Goodman/24 HYDROLOGY...Goodman/24

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