Area Forecast Discussion
Issued by NWS Upton, NY

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397 FXUS61 KOKX 240810 AFDOKX Area Forecast Discussion National Weather Service New York NY 410 AM EDT Thu May 24 2018 .SYNOPSIS...
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High pressure will dominate the weather through Saturday. A backdoor cold front pushes across the area Saturday night into Sunday morning, becoming nearly stationary just south and west of the area through Memorial Day. Another cold front follows on Tuesday with high pressure building in behind.
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&& .NEAR TERM /UNTIL 6 PM THIS EVENING/...
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Heights will gradually rise today as a longwave trough to the east shifts further into the northern Atlantic and ridging to the west builds. Sfc high pressure builds from the west today with just some thin cirrus and perhaps a few cu this aftn from convergence along seabreeze boundaries. Highs will range from mid 70s to around 80 across much of the Tri-State area. Lower 80s are expected in metro NY/NJ.
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&& .SHORT TERM /6 PM THIS EVENING THROUGH FRIDAY NIGHT/...
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Upper level ridging over the Great Lakes will flatten through Fri night as it traverses eastward as a result of vortexes remaining over the Labrador Sea and northern Greenland and a shortwave trough over the western Canadian provinces tracking east. At the sfc, a return flow develops tonight as high pres shifts off the New England/Mid Atlantic coasts and continues slowly into the western Atlantic through Fri night. This will result in an increasingly warm and humid airmass. Expect mostly clear skies with just some cirrus and perhaps a few cu Fri aftn/early eve. There is also the potential for stratus mainly Fri night (2nd night of southerly flow) across eastern LI and SE CT. Have hinted at this in the forecast with partly cloudy skies developing Fri night. Patchy fog is also a possibility mainly in rural areas both tonight and Fri night.
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&& .LONG TERM /SATURDAY THROUGH WEDNESDAY/...
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A broad upper level ridge across the southern two thirds of the country will get suppressed a bit south through early next week as a short wave trough progresses across the Great Lakes and Northeast states. Model differences exist with the magnitude of the latter feature, which sends a weak cold front across the region Tuesday. In the case of the GFS, the boundary more or less washes out as frontal wave passes to the south. The better agreement though comes with sending a backdoor cold front across the region Saturday night into Sunday morning, putting an end to a string of days well above normal. Showers and thunderstorms are also seeming more likely Saturday night into Sunday morning as the front interacts with modest instability, but a weakly sheared environment. Showers will likely linger into Sunday, but chances should diminish as high pressure builds southward across New England. Sufficient overrunning ahead of the approaching upper trough will be worthy of keeping the mention of showers in through Memorial Day. There could even be some scattered thunderstorms Sunday afternoon west of NYC, depending on how far to the south and west the boundary stalls. Additionally, with an easterly flow, temperatures continue to trend down Sunday and Monday. It may be a bit more tricky Monday with breaks in the cloud cover as the high weakens, especially for locations across the interior. Warmer weather then returns for the Tuesday through Wednesday timeframe as high pressure builds both aloft and at the surface.
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&& .AVIATION /08Z THURSDAY THROUGH MONDAY/...
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High pressure builds over the region today. VFR conditions are expected through the TAF period, however there`s a low to moderate chance that IFR stratus shifts into KGON this afternoon and a low chance that it then spreads into KISP/KBDR this evening. NW-N winds this morning will shift around to local seabreezes in the afternoon, except KSWF. Speeds around 10 kt or less. ...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: Seabreeze timing may be off by 1-2 hours. The afternoon KJFK haze potential forecast is GREEN...which implies slant range visibility 7SM or greater outside of cloud. KLGA TAF Comments: Seabreeze timing may be off by 1-2 hours. The afternoon KLGA haze potential forecast is GREEN...which implies slant range visibility 7SM or greater outside of cloud. KEWR TAF Comments: Seabreeze timing may be off by 1-2 hours. The afternoon KEWR haze potential forecast is GREEN...which implies slant range visibility 7SM or greater outside of cloud. KTEB TAF Comments: Seabreeze timing may be off by 1-2 hours. KHPN TAF Comments: Seabreeze timing may be off by 1-2 hours. KISP TAF Comments: Seabreeze timing may be off by 1-2 hours. .OUTLOOK FOR 06Z FRIDAY THROUGH MONDAY... .Thursday night...VFR. .Friday...VFR. SW winds around 15 kt with gusts 20-25 kt through early evening. .Saturday...Mainly VFR. Low chances of showers and thunderstorms near NYC Metro terminals and to the N and W starting in the afternoon with possible MVFR. Higher chance of showers and thunderstorms at night. .Sunday-Monday...MVFR or lower at times with a chance of showers and thunderstorms. Otherwise VFR.
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&& .MARINE...
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Sub-advsy conds prevail on all waters into Fri. A tightening pres gradient between low pres to the north and high pres over the western Atlantic on Fri could bring marginal SCA conds to the ocean waters Fri aftn/eve. A strengthening sfc inversion will be developing over the waters, so despite increasing winds aloft mixing potential will be limited. A 15-20kt sustained flow could however bring seas up to 5 ft. Remaining waters will be hazard free through Fri night. Have held off on issuing SCA at this time since it is marginal and a 3rd-4th period event. A weak gradient is forecast to remain across the water this weekend into early next week with sub-SCA conditions. Possible frontal wave development to the south on Tuesday will be watched for potential higher winds and seas.
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&& .HYDROLOGY...
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No hydrologic impacts are expected through Saturday. Localized heavy rainfall is a possibility as a cold front passes through the area Saturday night into Sunday morning. The main concern would be training of cells from west to east across the boundary.
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&& .EQUIPMENT... NYC NOAA Weather Radio Station KWO-35 (162.55 MHz) is off the air for an extended period of time. && .OKX WATCHES/WARNINGS/ADVISORIES... CT...None. NY...None. NJ...None. MARINE...None. && $$ SYNOPSIS...24/DW NEAR TERM...24 SHORT TERM...24 LONG TERM...DW AVIATION...JC MARINE...24/DW HYDROLOGY...24/DW EQUIPMENT...

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