Area Forecast Discussion
Issued by NWS Upton, NY

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000 FXUS61 KOKX 261227 AFDOKX Area Forecast Discussion National Weather Service New York NY 727 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/... Updated sky cover based on latest satellite trends. Most areas now partly sunny for the day. Otherwise...forecast on track. 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 /13Z SUNDAY THROUGH THURSDAY/... High pressure builds to the Mid-Atlantic coast today, then to the south of Long Island into Monday. VFR through the TAF period. Ceilings of 3500-5000 feet develop from NW to SE this morning (maybe into afternoon KISP/KGON). Ceilings should dissipate by around 23-01z (last KSWF). Gusty WNW winds into early evening, with gusts diminishing through the day. The flow backs to the west this evening with gusts abating and speeds falling under 10 kt. The winds become light and variable tonight at all but KLGA and KJFK, where the winds continue to back to the WSW-SW. For JFK/LGA/EWR - wind mainly to the left of 300 True/310 Magnetic through early afternoon, with increasing confidence in wind to the left of 300 True/310 Magnetic from mid afternoon through 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... Strongest wind gusts over the waters will be this morning, then diminishing in the afternoon as low level winds diminish to around 25 kt. Winds continue to diminish tonight from W to E. Have extended the SCA through midnight over the western waters and until 6am Monday on the eastern waters as a result. 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...12/Maloit SHORT TERM...12 LONG TERM...12/Maloit AVIATION...Maloit MARINE...Maloit HYDROLOGY...12

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