Area Forecast Discussion
Issued by NWS Upton, NY

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000 FXUS61 KOKX 231443 AFDOKX Area Forecast Discussion National Weather Service New York NY 1043 AM EDT Sun Oct 23 2016 .SYNOPSIS... Low pressure over southeastern Canada will gradually weaken over the next couple of days, while a clipper low and its associated cold front move through the area early Monday morning. High pressure builds across the area Tuesday and Wednesday, followed by a Pacific frontal system at the end of the week. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... Surface low pressure centered near the St Lawrence river will meander across southeastern Canada through today and into tonight as the upper closed low and negative trough remain across eastern Canada. The area remains in a gusty westerly flow through today with mixing up to 850 MB will see gusts in 25 to 30 KT range most of the day, especially into early this afternoon. With a well mixed boundary layer across the region temperatures will be fairly uniform...upper 50s to lower 60s. Drier air and weak subsidence will keep area cloud free until later this afternoon as clouds approach ahead of a shortwave moving through the northern stream. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM MONDAY/... Northern stream shortwave moves quickly east tonight and passes through the area after midnight. Decent lift along and ahead of the associated mid level short wave will result in a brief period of rain with up to a quarter inch possible. Most locations will dry out by daybreak Monday with the possible exception of far eastern LI and SE CT. Cold advection will follow through the day Monday with another shot of cold air following a short wave trough Monday evening. Amplifying upper ridge over the western U.S. ahead of the next Pacific storm system will help to amplify the downstream trough across eastern Canada and the northeast. In addition, an upstream block resides across the central Atlantic. This will result in a deep-layered NW flow across the area with a shot of unseasonably cold air to arrive Monday night and persist into mid week. Gusty northwest winds will continue during this time with weakening low pressure over eastern Canada and polar high pressure building southeast from central Canada. && .LONG TERM /MONDAY NIGHT THROUGH SATURDAY/... Upper trough remains across the northeastern portion of the country early to mid week, as ridge to the west eventually flattens per global models. Differences arrive with handling of shortwave that develops across the upper mid west as it traverses east late in the week. At the surface, low pressure associated with lingering upper trough moves slowly across eastern Canada, as high pressure builds out of central Canada and into the Great Lakes Region through mid week. The high briefly slides across the area Thursday before giving way to low pressure Thursday and Friday. Frontal boundaries, first warm front followed by the cold front, impact the area from late Thursday, into Friday. For Saturday, forecast becomes less clear. A possible weak frontal boundary may move through Saturday, but confidence in this remains low at this time. Generally dry conditions are anticipated through Wednesday night as high pressure slowly builds. Cyclonic flow could result in more cloud cover each day, especially into New England Tuesday and possibly Wednesday. The best chance for rain looks to be late Thursday, Thursday night into Friday. ECMWF slower with upstream system compared to usually quicker GFS. Temperatures will be below normal Tuesday and Wednesday, then slowly moderate closer to normal Thursday through Saturday. && .AVIATION /14Z SUNDAY THROUGH THURSDAY/... High pressure builds to the south today with strong low pressure over eastern Canada. A cold front moves through tonight into early Monday. Gusty WNW winds continue today. Gusts 25-30 kt expected through the late afternoon. A peak gust up to 35 kt cannot be ruled out, but this will not be a frequent occurrence. Winds and gusts diminish this evening, with winds backing to the SW around 7-10 kt overnight. VFR through the TAF period. There is a low chance for MVFR in light rain late tonight into early monday morning. .Outlook for 12Z Monday through Thursday... .Monday Morning...Mainly VFR. Low chance for MVFR in light rain early. Gusty SW-NW flow. .Monday Afternoon-Tuesday Night...VFR. NW winds G20-25KT. Winds diminish Tuesday night. .Wednesday-Thursday...Mainly VFR. && .MARINE... Little change to the winds, gusts and seas across the forecast waters through today. On the synoptic scale, a steep pressure gradient remains across the waters between deep low pressure meandering across southeastern Canada and high pressure centered across the southeastern states. This will keep gales across all waters especially with mixing depth increasing this morning into this afternoon. The pressure gradient weakens tonight with a clipper type low passing through the area. The result will be wind gusts becoming more occasional and diminishing. SCA conditions will be likely early in the evening, but will eventually just be confined to the ocean waters. However, after the associated cold frontal passage, winds will resume gusting. Again, SCA conditions will be probable across much of the waters for Monday through Tuesday. Winds diminish again with a more substantial decrease of the pressure gradient Tuesday night with a Canadian high approaching. High pressure remains across the waters through early Thursday. && .HYDROLOGY... Up to a quarter inch of rain is possible tonight with a fast moving area of low pressure. Rainfall of 1/2 inch or more is possible Thursday into Friday. No hydrologic impacts are anticipated. && .OKX WATCHES/WARNINGS/ADVISORIES... CT...None. NY...None. NJ...None. MARINE...Gale Warning until 6 PM EDT this evening for ANZ330-335-338- 340-345-350-353-355. && $$ SYNOPSIS...DW/MET NEAR TERM...MET SHORT TERM...DW/MET LONG TERM...DW/PW AVIATION...DS MARINE...JM/DW/MET HYDROLOGY...DW/PW is the U.S. government's official web portal to all federal, state and local government web resources and services.