Area Forecast Discussion
Issued by NWS Upton, NY

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000 FXUS61 KOKX 201346 AFDOKX Area Forecast Discussion National Weather Service New York NY 946 AM EDT Thu Sep 20 2018 .SYNOPSIS... High pressure will build down from the Canadian Maritimes through Friday morning, then weaken Friday afternoon ahead of an approaching cold front. The front will move across Friday night into Saturday morning, settling to the south into early next week as strong high pressure builds to the north. A slow moving frontal system will approach during the middle of next week. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... BKN-OVC sky conditions across much of the forecast area this morning will gradually dissipate as sfc high pres builds into New England and heating/mixing commences. Mostly sunny/partly cloudy skies are expected across the entire Tri-State area by afternoon. High temps are a blend of GFS/NAM MOS guidance, with all but the highest elevations reaching the lower 70s. A moderate rip current risk exists for today. This could be upgraded to a high risk if winds become more E vs NE today. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM FRIDAY/... As a warm front passes to the north Thu night into Fri morning, skies should become mostly cloudy, with a shower or two possible well NW of NYC. Skies should remain mostly cloudy well NW into Fri afternoon well in advance of a cold front as moisture remains trapped beneath a low level inversion, with partly cloudy skies east. S winds should increase, and also become gusty Fri afternoon, with a sea breeze enhanced by synoptic-scale flow, and perhaps some stronger gusts than fcst especially NW of NYC Fri afternoon, depending on the strength of the inversion. If on the weaker side, areas NW of NYC could see gusts 25-30 kt well in advance of the approaching cold front. High temps on fri should be 70-75, which is close to average. Rip current outlook: Moderate, possibly high for NYC and Nassau if the sea breeze is stronger than expected. && .LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/... A zonal flow will generally prevail through the weekend, with the H5 flow amplifying across North America early next week. Differences in timing and amplitude with the digging western trough and eastern ridging remain through the middle of next week. Cold front moves across the area Fri night accompanied by showers and tstms. There is a low chance that strong upstream convection could produce strong/damaging winds in areas NW of NYC, but do not have a lot of confidence in this attm. The convective line forecast to develop over western NY/PA during the day Fri is expected weaken as it approaches and moves across the local area into a more stable environment during the late evening and overnight hours. Thereafter, a fall type air mass is likely for this weekend and into early next week as the cold front settles to the south and Canadian high pressure builds into New England. With close proximity to stalled boundary and under periphery of the ridge/upper jet, could be looking at mid and high clouds streaming across through the weekend. A few sprinkles or light showers may still possible across NYC metro and Long Island if the boundary stalls close enough. Then a gradually increasing chance for stratus and shower development Monday night with approach of the next frontal system. There is a good signal for a return to a moist tropical environment for the middle of the week as deep trough amplifies into the Central states, and Bermuda ridging holds strong. A slow-moving frontal system will bring potential for rounds of showers and thunderstorms, particularly across the interior, during this time along with a warm and unseasonably humid air mass. && .AVIATION /14Z THURSDAY THROUGH MONDAY/...
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High pressure remains over the region today, then shifts offshore Fri. Areas of MVFR improving to VFR at all terminals by 15Z. Stratus will redevelop again tonight with cigs around 2000 ft expected. Improvement back to VFR expected after 13Z Fri. Winds shift to the SE through the day, and remain SE tonight. Winds shift further to the S on Fri, with speeds increasing through the day. NY Metro Enhanced Aviation Weather Support... Detailed information, including hourly TAF wind component fcsts, can be found at: http:/www.weather.gov/zny/n90 KJFK TAF Comments: Amendments for timing of improvement to VFR possible. The afternoon KJFK haze potential forecast is YELLOW, which implies slant range visibility 4-6SM outside of cloud. KLGA TAF Comments: Amendments for timing of improvement to VFR possible. The afternoon KLGA haze potential forecast is GREEN, which implies slant range visibility P6SM outside of cloud. KEWR TAF Comments: Amendments for timing of improvement to VFR possible. The afternoon KEWR haze potential forecast is GREEN, which implies slant range visibility P6SM outside of cloud. KTEB TAF Comments: Amendments for timing of improvement to VFR possible. KHPN TAF Comments: Amendments for timing of improvement to VFR possible. KISP TAF Comments: No unscheduled amendments expected. .OUTLOOK FOR 12Z FRIDAY THROUGH MONDAY... .Friday-Friday night...VFR during the day, then a chance of showers and thunderstorms with MVFR at night. .Saturday-Sunday...An early shower Saturday, then VFR through the weekend. .Monday...Chance of MVFR especially in the afternoon.
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&& .MARINE... SCA remains in effect for the ocean today, seas 4-6 ft today and running about 1 ft above guidance. It is questionable whether 5-ft seas could linger into this evening, so SCA not extended into that time frame. Increasing S-SW flow ahead of an approaching cold front should produce SCA conds on most of the local waters late Fri/Fri night. Winds should diminish by Sat morning, although SCA swells on the ocean will likely linger into Saturday morning. Sub advsy conditions are then expected on all waters through the remainder of the weekend as high pressure builds to the north. Easterly winds likely strengthen Monday into Monday night ahead of an approaching warm front, with potential for SCA conditions to develop on the ocean. && .HYDROLOGY... No significant hydrologic impacts expected through Tue. There is potential for rounds of heavy showers and thunderstorms mid to late next week. && .EQUIPMENT... NYC NOAA Weather Radio Station KWO-35 (162.55 MHz) remains off the air for an extended period of time. && .OKX WATCHES/WARNINGS/ADVISORIES... CT...None. NY...None. NJ...None. MARINE...Small Craft Advisory until 6 PM EDT this evening for ANZ350- 353-355. && $$ SYNOPSIS...Goodman/24 NEAR TERM...Goodman SHORT TERM...Goodman LONG TERM...24 AVIATION...JMC/JP MARINE...Goodman/24 HYDROLOGY...Goodman/24 EQUIPMENT...

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