Area Forecast Discussion
Issued by NWS Upton, NY

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000 FXUS61 KOKX 250612 AFDOKX Area Forecast Discussion National Weather Service New York NY 212 AM EDT THU AUG 25 2016 .SYNOPSIS... High pressure will remain to the south through Thursday. A weakening front will approach Thursday night, then move across on Friday, followed by high pressure this weekend. A cold front will approach early next week, and may then linger nearby through Wednesday. && .NEAR TERM /UNTIL 6 AM THIS MORNING/... Upper ridge remains anchored to our south tonight, as the area remains on the southern edge of the westerlies. Patch of high clouds will move across next several hours, with mostly clear skies still anticipated. Expect temps tonight to run a little warmer than the past couple of nights as the air mass modifies. Lows will range from the lower 70s in NYC, to the 60s elsewhere. && .SHORT TERM /6 AM THIS MORNING THROUGH 6 PM FRIDAY/... Ridge remains anchored to the south Thursday and Thursday night as the area remains on the southern edge of the westerlies. A weak trough approaches from the west. Expect an increase in mid and higher level clouds from the west late in the day, with a good amount of sunshine all day further east. Will cap pops to slight chance, mainly for western sections late in the day. Slight chance pops spread east at night. High resolution models indicate spotty showers moving across the area at night. NWP model solutions output minimal QPF, or keep conditions dry for the most part. High temps will range from around 80 over eastern coastal locations, to the upper 80s in northeast NJ. At night, persistent southerly flow along with plenty of clouds will result in warm temps, with a much smaller range in low temps, upper 60s to middle 70s. There is a moderate risk for rip current development at the ocean beaches Thursday into Thursday evening. && .LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/... The latest NWP model suite is in good agreement through this weekend, then they begin to diverge a bit early next week. A strong upper anticyclone will build towards the region Friday and then remain over the Middle Atlantic this weekend. The ridge may begin to shift south and weaken a bit on Monday as a northern stream shortwave traverses across SE Canada. Differences arise with the timing and how much the ridge breaks down. Differences continue through the middle of next week with how much ridging rebuilds aloft. A weak cold front will move through late Friday. Friday will be hot and humid with temperatures surging into the upper 80s and lower 90s. Heat indices will reach the middle 90s and could reach the upper 90s if dew points stay higher than forecast in the afternoon. This is possible if more moisture pools along and ahead of the cold front. However, thermal profiles show potential mixing up to around 850 hPa in the afternoon which should help to lower dew points into the upper 60s in the afternoon. There will be a good amount of dry air in the upper atmosphere as heights actually will rise. Instability is also marginal as there may be a cap around 15kft, so have lowered PoPs to just slight chance. High pressure builds down from SE Canada this weekend with a light northerly flow and slightly cooler air. The most noticeable difference will be less humidity as dew points generally in the lower and middle 60s. This will preclude the need for a heat advisory in NYC since heat indices should only be in the upper 80s this weekend, close to actual air temperatures. Another cold front approaches late Sunday night into Monday. The main shortwave forcing passes well to the north so have mainly kept PoPs at slight chance with chance PoP across the interior. The boundary may then stall near the area Tuesday into Wednesday. This will all be tied to how strong the ridge aloft ends up and if the upper jet stays well to the north leaving the boundary behind. Overall, above normal and humid conditions should continue next week. && .AVIATION /06Z THURSDAY THROUGH MONDAY/...
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High pressure off the Northeast coast slowly moves east through tonight, giving way to a weak frontal system approaching from the Ohio Valley. A pre-frontal trough will approach from the west this afternoon. VFR through the TAF period. There is a low chance of showers northwest of the New York City during the afternoon and early evening hours. Winds generally SSW less then 10 KT, to light and variable at outlying terminals overnight. Winds increase during the morning hours and become southerly. Gusts up to 20KT possible near the coast. .Outlook for 06Z Friday through Monday... .Thursday night-Friday...Mainly VFR. Slight chance of showers with MVFR conditions. Isolated thunder possible on Friday. .Friday night-Monday...VFR.
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&& .MARINE... Southerly winds should run around 15 kt overnight, with ocean seas as high as 4 ft near the NY harbor entrance and 2-3 ft elsewhere, higher than originally forecast. With high pressure remaining just to the south, southerly flow will prevail through Thursday night. Speeds will increase again late in the day Thursday, and winds over the ocean waters may approach SCA criteria. Ocean seas should build to at least 4 ft by late Thu afternoon into Thu night. Guidance suggests 5 ft seas are not out of the question. For the non ocean waters, seas/waves should remain 2 ft or less. There remains the potential for a tropical swell on the waters late this weekend and early next week. Seas could build to around 5 ft Sunday into Monday with this long period SE swell. && .HYDROLOGY... No significant widespread precipitation is expected into next week. && .OKX WATCHES/WARNINGS/ADVISORIES... CT...None. NY...None. NJ...None. MARINE...None. && $$ SYNOPSIS...DS/PW NEAR TERM...JC/Goodman/PW SHORT TERM...PW LONG TERM...DS AVIATION...DW MARINE...JC/Goodman/DS/PW HYDROLOGY...DS/PW

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