Area Forecast Discussion
Issued by NWS Upton, NY

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000 FXUS61 KOKX 140318 AFDOKX Area Forecast Discussion National Weather Service New York NY 1018 PM EST Fri Jan 13 2017 .SYNOPSIS... Strong high pressure over the Great Lakes this evening builds east and into the area by daybreak. The high passes offshore Saturday afternoon with a weak wave of low pressure passing well to the south Saturday night. High pressure builds over the region Sunday into Monday, and moves offshore Monday night as a warm front approaches, then moves through Tuesday or Tuesday night. A cold front follows Wednesday into Wednesday night. Weak high pressure builds in Thursday. && .NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
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Temperatures and dewpoints were again slightly adjusted to better match observed trends. Canopy of mid level and cirrus clouds continues to move in from the west. Min temperatures were slightly increased. Otherwise, no other remarkable changes made to the forecast database. A strongly confluent flow aloft between the northern and southern branches of the polar jet will allow strong high pressure over the Great Lakes this evening to build east and into the Northeast by daybreak. At the same time, an upper low off the west coast will steer plenty of mid and high level clouds across the region this evening. In addition, a gusty NW flow early will subside as the high builds in from the west. Overnights lows will return to nearly seasonable levels, ranging from the teens well inland to 20 to 25 near the coast.
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&& .SHORT TERM /6 AM SATURDAY MORNING THROUGH SATURDAY NIGHT/...
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High pressure builds across the area in the morning and then passes to the east in the afternoon. A weak frontal wave passes well south off the Mid Atlantic coast late in the day. The general trend in the model guidance the last several days has been weaker and farther south with this system. While there is some weak warm advection and moisture in place Saturday afternoon/evening, the amount of dry air in the low-levels and subsidence will be difficult to overcome. Thus, have continued to trend down with the chance of light snow, mainly for the NYC metro and LI during the afternoon/early evening hours. More than anything, this looks to be nothing more than a few passing flurries. In a worst case scenario, snow amounts look to be under an inch. Daytime highs under cloud cover will struggle on Saturday to get out of the lower 30s with lows Saturday night in the 20s.
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&& .LONG TERM /SUNDAY THROUGH FRIDAY/... High pressure builds in from the northwest on Sunday and Monday. Both days will be dry with high temperatures a little above normal. Slight ridging continues aloft Monday night into Tuesday morning, but shortwave lift and isentropic lift ahead of a warm front are still shown by models. With increasing moisture, there will be at least a slight chance of PCPN late at night over the western zones, but PCPN becomes a little more likely across the entire forecast area during the day Tuesday. A warm nose aloft is still progged to be warm enough to preclude snow as a likely PCPN type. Rain with a potential brief period of sleet would therefore be more likely to occur, with freezing rain for some inland spots until surface temps warm up enough by late Tuesday morning. The timing of both warm front and cold front passages thereafter are uncertain with model disagreement. Will carry chance PoPs Tuesday night through Wednesday night with rain as the PCPN type. Temperatures well above normal during this period. There at least appears to be agreement that we dry out by Thursday as weak high pressure builds in from the west. A shortwave and weak surface trough may then bring a shower in spots on Friday. Highs both days still averaging well above normal. && .AVIATION /03Z SATURDAY THROUGH WEDNESDAY/...
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North winds diminish tonight as high pressure builds to the north. Winds tomorrow will go to the northeast for the morning, then southerly in the afternoon. Wind speeds will be light. Light snow will be possible late Saturday afternoon-evening as a low pressure system passes to the south, with the best chance across southern terminals. For other terminals confidence is too low at this time to put in TAF. NY Metro Enhanced Aviation Weather Support... Detailed information, including hourly TAF wind component forecasts, can be found at: http:/www.weather.gov/zny/n90 .OUTLOOK FOR 0Z SUNDAY THROUGH WEDNESDAY... .Saturday night...Sub VFR is possible in light snow for Saturday evening. Best chance of Sub VFR will be across southern terminals. .Sunday...VFR. .Monday...VFR. .Monday night-Tuesday...MVFR or lower possible in rain near the coast, and wintry mix inland. .Wednesday...MVFR or lower possible in rain.
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&& .MARINE...
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SCA conditions are expected on the eastern ocean waters (east of Fire Island Inlet) until 6Z. For other waters, below SCA conditions expected. Winds and seas gradually subside into the overnight as high pressure builds toward the waters. Sub-SCA conditions are then forecast through Saturday night. NW winds develop late Saturday night behind low pressure well to the south and east.Gusts on the ocean waters could get up to 20 kt by daybreak Sunday, Winds diminish later Sunday with tranquil conditions on the waters following through Tuesday as a high pressure ridge slowly shifts through the region. Winds and seas then build Tuesday night into Wednesday as the pressure gradient tightens in response to an approaching low pressure system. There will be chance of SCA conditions, mainly on Wednesday.
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&& .HYDROLOGY... No significant precipitation is forecast this weekend into next week. && .OKX WATCHES/WARNINGS/ADVISORIES... CT...None. NY...None. NJ...None. MARINE...Small Craft Advisory until 1 AM EST Saturday for ANZ350-353. && $$ SYNOPSIS...JC/DW NEAR TERM...JM/DW SHORT TERM...DW LONG TERM...JC AVIATION...JE/NV MARINE...JC/JM/DW HYDROLOGY...JC/DW

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