Area Forecast Discussion
Issued by NWS Upton, NY

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455 FXUS61 KOKX 261651 AFDOKX Area Forecast Discussion National Weather Service New York NY 1151 AM EST Sun Feb 26 2017 .SYNOPSIS... High pressure builds along the Eastern Seaboard today. The strengthening high drifts over the Atlantic on Monday. A warm front sets up in the vicinity on Tuesday, followed by a cold frontal passage Thursday. A clipper low may impact the area by the end of the week. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... Forecast on track...Only changes at this time was some lowering of cloud coverage for today as downslope is effectively dissipating the stratocumulus - only the Hudson Valley is mostly cloudy. Low pressure was over the Canadian Maritimes this morning, with the associated cold front extending southward over the Atlantic. Some snow showers and flurries were noted across Upstate New York, but downsloping flow and subsidence are expected to keep the forecast area dry today. A few flurries cannot be ruled out of a potential broken deck around 4500 feet. WNW winds this morning should gust to 20-35mph, strongest near the coast and over NYC. Wind gusts should diminish this afternoon, as 950-850 winds diminish to around 25 kt by evening. The guidance was in good agreement so a blend was used for temperatures. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 AM MONDAY/... After the diurnal cumulus dissipates this evening, model time heights suggest the mid and high clouds will hold off for all if not most of the night. With winds decoupling, especially in the usual outlying spots, temperatures were nudged slightly below guidance. && .LONG TERM /MONDAY THROUGH SATURDAY/... The forecast was generally on track for the extended. The most significant change was to include a chance for snow on Friday. An increase in mid level moisture will produce overcast skies by the end of Monday. A lack of deep moisture and lift are limiting factors for the development of precipitation at this time. The forecast has therefore been kept dry through Monday night. Rain chances increase Tuesday and Wednesday as Gulf moisture infiltrates the region. Gusty winds of 35-45 mph are likely Thursday with strong low level cold advection behind the cold front and winds from 950-850 hPa progged at 40-50kt. There is some potential for wind advisory criteria to met both in coastal areas and at higher elevations. After the main band of rain with the front, there could be some residual scattered showers with steepening lapse rates and strong vorticity advection. With the cold air pouring in, these showers could mix with or change to snow. The passage of an Alberta Clipper then appears to be a little more likely on Friday per the 00Z model suite. As a result, a chance of snow has been introduced to the forecast. Cold on Saturday with wind chills potentially in the teens for most of the day. && .AVIATION /18Z SUNDAY THROUGH FRIDAY/... High pressure builds to the Mid-Atlantic coast today, then to the south of Long Island into Monday. VFR through the TAF period. CT-BKN Stratocumulus of 4-5 KFT is mainly confined to the Lower Hudson Valley this afternoon. Gusty NW flow (300-320 degrees direction) at 25-30 kt will become more in the range of 20-25 kt while backing in direction 20-30 degrees this afternoon. Clouds and winds diminish tonight. .OUTLOOK FOR 12Z MONDAY THROUGH THURSDAY... .Monday-Monday evening...VFR. SW winds G15-20KT possible Monday afternoon. .Late Monday night-Wednesday...Chance of MVFR or lower. LLWS possible Tuesday-Wednesday. .Wednesday night...IFR or lower possible. SW winds G15-25KT possible along coast. .Thursday...MVFR possible. W-WNW winds G30-40KT probable. && .MARINE... Wind gusts over the waters diminishing in the afternoon as low level winds diminish to around 25 kt. Winds continue to diminish tonight from W to E. Thus, SCA through midnight over the western waters and until 6am Monday on the eastern waters. There is some question on Monday as to whether or not we mix down any of the 25-30KT low level winds, maybe by late afternoon - with the best chance closer to the coast. Given confidence in occurrence of SCA of less than 80 percent, did not extend SCAs over the eastern waters into Monday. Low level mixing should be limited Monday night and Tuesday, so even though low level winds are 25-35 kt, have gone with a sub-small craft forecast. The pressure gradient tightens Tuesday night, allowing for at least seas to possibly build to SCA levels east of Moriches Inlet. The pressure gradient continues to tighten on Wednesday, with SCA conditions likely on the coastal ocean waters, and possible on the non-ocean waters. These conditions should continue through Wednesday night. With strong cold advection forecast for Thursday and low level winds of 40-50kt progged in some guidance, gales are likely on the coastal ocean waters and possible on the non-ocean waters. There is a small chance for gusts to storm force as well on the coastal ocean waters. These threats will be highlighted in the HWO. && .HYDROLOGY... The next chance for widespread precipitation is the middle of next week, where around and inch of rain is possible. && .OKX WATCHES/WARNINGS/ADVISORIES... CT...None. NY...None. NJ...None. MARINE...Small Craft Advisory until midnight EST tonight for ANZ335-338- 345-355. Small Craft Advisory until 6 AM EST Monday for ANZ330-340-350- 353. && $$ SYNOPSIS...12 NEAR TERM...Tongue SHORT TERM...12 LONG TERM...12/Maloit AVIATION...Maloit/JM MARINE...Maloit HYDROLOGY...12 is the U.S. government's official web portal to all federal, state and local government web resources and services.