Area Forecast Discussion
Issued by NWS Upton, NY

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096 FXUS61 KOKX 221953 AFDOKX Area Forecast Discussion National Weather Service New York NY 353 PM EDT Sun Sep 22 2024 .SYNOPSIS...
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High pressure continues to build in from the northeast tonight and will remain in control through at least Tuesday. A frontal system then approaches on Wednesday and moves across on Thursday. High pressure slowly returns Friday and Saturday.
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&& .NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
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Offshore low pressure is still slowly departing as high pressure noses in from the northeast. Aloft, heights rise as a shortwave ridge builds in. The ridge axis will pass overhead late tonight. The orientation of the surface features will allow for the persistent NE flow to continue, with the pressure gradient weakening very gradually. For lows tonight, went with the warmer NBM across the coast, LI, NYC and northeast NJ as winds here will likely be a bit stronger. Blended in some MOS guidance and NBM10th percentile to get cooler temps up across the interior where winds will be lighter.
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&& .SHORT TERM /6 AM MONDAY MORNING THROUGH TUESDAY/...
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High pressure remains in control through at least Tuesday. The aforementioned upper level ridge axis will pass east early Monday and a weak shortwave trough looks to swing through later on Monday. Some of the guidance is hinting at some QPF Monday evening for far wester locations, but went dry for now given the dry NE flow that will be out ahead of any showers approaching the area. Thinking if anything does reach the area it may only be sprinkles and not measurable. Upper level ridging builds back in for Monday night and Tuesday. High temperatures on Monday and Tuesday look to be a few degrees below normal for late September, upper 60s to low 70s. Lows Monday night will be pretty similar to tonight.
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&& .LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/...
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Key Points: * Dry into Tue night. * Chance of showers Wed into Thu with a passing frontal system. * Greater likelihood of dry weather from Fri into the weekend. Sfc high pressure nosing down from Atlantic Canada and ridging aloft on Tue will both slowly give way to a frontal system from the west during mid week. Chance PoP enters the forecast from NYC west daytime Wed, overspreading the entire fcst area Wed night into Thu morning. By Thu, a complex pattern will have taken shape over North America, with an omega block developing as upper ridging gets pinched off over the upper Great Lakes region, one closed low moves across Eastern Canada into the western Atlantic, and another closed low remains nearly stationary over the Plains and the Mississippi Valley. The low moving across Canada should send a back door front down through on Fri, with sfc ridging once again nosing down from ern Canada from that point on into the weekend. Temps on Wed will be fairly close to normal, then above normal temps expected from Thu into the weekend.
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&& .AVIATION /19Z SUNDAY THROUGH FRIDAY/...
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High pressure eventually builds southward into the area as low pressure offshore slowly moves farther out to sea. Mainly VFR conditions are expected through the TAF period with exception of KGON, where MVFR stratus is forecast late tonight into Monday. There is a chance for widespread MVFR stratus late tonight into early Monday. Have all terminals except for KSWF with at least a tempo group for a part of the time, with terminals east of NYC expecting to have a longer period of MVFR. Winds will be NE near 5-10 kts through much of the TAF period. Gusts near 20-25 kt east of NYC terminals forecast until early evening with KGON having gusts last longer into tonight. KGON and KISP are also forecast to have gusts 15-20 kt Monday late morning into afternoon. ...NY Metro (KEWR/KLGA/KJFK/KTEB) TAF Uncertainty... Occasional wind gust to 15-20 kt possible this afternoon and this evening. Timing of MVFR could be off by a few hours. OUTLOOK FOR 18Z MONDAY THROUGH FRIDAY... Monday: Mainly VFR. Tuesday: VFR. Wednesday: Chance of showers with MVFR possible. E wind gusts 15-20 kt day into eve. Thursday: Chance of showers, mainly early, with MVFR possible. Friday: VFR. Detailed information, including hourly TAF wind component forecasts, can be found at: https:/www.weather.gov/zny/n90
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&& .MARINE...
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Elevated long period swells from slow departing offshore low pressure will continue for several days. A Small Craft Advisory remains in effect on the ocean waters and has been extended through Tuesday. This will likely continue to be extended over the next several forecast cycles. Seas peak tonight through Monday around 6 to 8 feet and then slowly lower into the middle of the week. An extended period of hazardous 5+ foot seas should continue into at least Wednesday night. Seas may either subside below 5 ft by Thursday, or seas may at least be confined closer to 20 nm offshore and beyond.
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&& .HYDROLOGY...
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There are no hydrologic concerns through next weekend. Basin avg QPF from Wed into Thu night should range mostly from 1/4 to 1/2 inch, with localized amounts of 1/2 to 1 inch possible in any heavier showers.
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&& .TIDES/COASTAL FLOODING...
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Coastal flooding will continue into Monday, but impacts and areal coverage will be on the downswing as astronomical tides continue to lower. The offshore low responsible for the easterly swell that has helped pile water into the area will work slowly southeast through early next week. While astronomical high tides will steadily lower over the next few days, easterly swells from the low will continue to keep waters levels 1 1/2 to 2 1/2 feet above normal. That being said, most locations need 2 to 3 ft of surge to reach minor coastal flood benchmarks for the nighttime high tide cycles, and 1 to 2 1/2 feet during the afternoon high tide cycles. Based on these trends, after Monday afternoon, any flooding should be localized through Tuesday and primarily across the south shore back bays of western LI. As for the surge guidance, Steven`s continues to be running high in the back bays. Plan to still take an average of the ETSS, ESTOFs, and Steven`s with some adjustments based on recent performance. However, Steven`s is much slower in taking water levels down. In some instances, Steven`s is about 1 to 1 1/2 feet higher. From past experience, the back bays can be slow to drain with a persistent swell. So will have to watch the back bays closely to see if the the minor flooding may hold into Tuesday. Do not see any issues beyond that time. For tonight, just have a coastal flood statement up for the S Nassau and SW Suffolk. Lindenhurst tends to hold onto high waters levels in a prolonged period of easterly swells and is the main reason the statement is up for SW Suffolk. For Monday`s high tide, advisories are in effect for Lower NY Harbor, S Queens, and S Nassau, and portions of the coastline adjacent to western LI Sound. To the east of these locations, coastal flood statements are in effect for waters levels approaching or just exceeding minor coastal flood benchmarks. The high risk of rip currents continues Monday and Tuesday with offshore low pressure still bringing long period E/SE swells.
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&& .OKX WATCHES/WARNINGS/ADVISORIES...
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CT...Coastal Flood Advisory until 4 PM EDT this afternoon for CTZ009-010. Coastal Flood Advisory from 2 PM to 6 PM EDT Monday for CTZ009. NY...Coastal Flood Advisory until 4 PM EDT this afternoon for NYZ071>075-078-080-176>179. Coastal Flood Advisory from 2 PM to 6 PM EDT Monday for NYZ071. Coastal Flood Advisory from 11 AM to 3 PM EDT Monday for NYZ074-075-178-179. High Risk for Rip Currents through Tuesday afternoon for NYZ075-080- 081-178-179. NJ...Coastal Flood Advisory until 4 PM EDT this afternoon for NJZ006-106-108. Coastal Flood Advisory from 11 AM to 3 PM EDT Monday for NJZ006-106-108. MARINE...Small Craft Advisory until 6 PM EDT Tuesday for ANZ350-353-355.
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&& $$ SYNOPSIS...BG/JT NEAR TERM...JT SHORT TERM...JT LONG TERM...BG AVIATION...JM MARINE...BG/JT HYDROLOGY...BG/JT TIDES/COASTAL FLOODING...DW