Area Forecast Discussion
Issued by NWS Upton, NY

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000 FXUS61 KOKX 150522 AFDOKX Area Forecast Discussion National Weather Service New York NY 1222 AM EST Sun Jan 15 2017 .SYNOPSIS...
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High pressure builds Sunday and Sunday night. High pressure across the region Monday drifts offshore Monday afternoon into Monday night. A warm front approaches from the west Tuesday and slowly moves in Tuesday into Tuesday night. It moves through and to the north of the area late Tuesday night with a cold front to follow for early Wednesday. Weak high pressure builds in from the west from mid to late week.
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&& .NEAR TERM /UNTIL 6 AM THIS MORNING/...
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Snow has ended across the area and skies will gradually clear as drier air advects eastward and subsidence develops in the departing low`s wake. Temperatures tonight are generally on track for lows mainly in the 20s across the CWA...with readings right around 30 in NYC. Only minor updates needed for current dew point trends.
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&& .SHORT TERM /6 AM THIS MORNING THROUGH 6 PM MONDAY/... Initial shortwave aloft passes well east, with a general W/NW flow expected aloft through this time frame. Surface high pressure builds across the Great Lakes Region/Ohio Valley toward and over the area Sunday night. Dry weather, with generally clear skies, can be expected. Temperatures will rise to the upper 30s to middle 40s, slightly above normal. A NW breeze during the day diminishes at night as the pressure gradient relaxes. Good radiational cooling conditions prevail, with low temperatures ranging from near 30 in NYC, to the teens across the normally colder spots, interior and pine barrens of eastern Long Island. && .LONG TERM /MONDAY NIGHT THROUGH SATURDAY/... Upper levels exhibit split jet structure with subtropical jet approaching the region Monday night into Tuesday. This jet amplifies Tuesday night into Wednesday with local region being in the left front quadrant of enhanced synoptic lift. This jet will then become more suppressed to the south of the region late Wednesday through the end of the week. Upper and mid levels show slight ridging Monday into Tuesday and then a nearly steady geopotential tendency Tuesday afternoon into Tuesday evening before becoming negative Tuesday night through Wednesday. Weak ridging builds in slowly from the west thereafter. At the surface, high pressure will be across the region and will present an airmass with slightly above normal temperature under a mostly sunny sky and light winds. The sky remains mostly clear to start Monday night and winds remain light so radiational cooling will be optimal the first half of the night. Then, clouds increase as a warm front approaches with associated isentropic lift. The warm air advection aloft will set temperatures a few degrees above freezing within the 1kft to 5kft layer and with surface temperatures for most locations Monday night into early Tuesday, if precipitation arrives early enough, this would be in the form of freezing rain. Later on Tuesday by mid to late morning, temperatures rise with light onshore flow and any freezing rain would change to plain rain. The progression of this would be from south to north with interior locations being last to change to plain rain. Temperatures are expected to rise into the upper 30s to lower 40s Tuesday. Not much of a drop in temperatures Tuesday night as warm front works its way through the region. Rain continues and then tapers off late Wednesday into Wednesday night from west to east behind the cold front. Low pressure slowly moves northeast of the region eventually into the Canadian Maritimes by end of the week. Weak high pressure builds in from the west. Dry weather expected Wednesday night through end of the week. Temperatures are near normal Tuesday and above normal Tuesday night through the rest of the forecast period. && .AVIATION /05Z SUNDAY THROUGH THURSDAY/...
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An area of low pressure will track well to the southeast early this morning, followed by high pressure building over the area into tonight. VFR through the TAF period, except for MVFR ceilings probably lingering to around 8z at most terminals. Light and variable winds tonight become NNW-NW at under 10 kt this morning. Winds become light and variable again from late this afternoon through this evening. .OUTLOOK FOR 06Z MONDAY THROUGH THURSDAY... .Late Sunday night-Monday evening...VFR. .Late Monday night...Very low chance of MVFR or lower far western terminals. There is a chance of freezing rain where it does precipitate (except city terminals where should be just rain). .Tuesday...IFR or lower possible. Freezing rain probable at interior terminals through at least Tuesday morning and possible at coastal terminals Tuesday morning. .Tuesday night-Wednesday...IFR or lower probable. Conditions improving late Wednesday. S-SE winds G15-25kt possible Tuesday night. .Wednesday night-Thursday...VFR likely with low chance of MVFR. W-NW winds G15-25kt possible.
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&& .MARINE...
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Made minor changes this update to reflect the latest trends in observations and guidance. The forecast appears on track. The pressure gradient tightens to moderate over the waters through Sunday night. Sustained winds should go up to 15 kt and gusts up to 20 kt through Sunday night, so no headlines planned. Seas through Sunday night remain 1 ft or less across the non ocean waters, and less than 3 feet across the ocean waters. SCA probable on the ocean Wed through Thu with otherwise sub SCA conditions expected for other marine areas and for other time periods regarding the long term forecast marine period Mon through Thu.
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&& .HYDROLOGY... No significant precipitation is forecast through the remainder of the weekend and into next week. As a result, no hydrologic impacts are expected. && .OKX WATCHES/WARNINGS/ADVISORIES... CT...None. NY...None. NJ...None. MARINE...None. && $$ SYNOPSIS...JM/PW NEAR TERM...Maloit/JM/PW SHORT TERM...PW LONG TERM...JM AVIATION...Maloit MARINE...Maloit/JM/PW HYDROLOGY...JM/PW

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