Area Forecast Discussion
Issued by NWS Upton, NY

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000 FXUS61 KOKX 140142 AFDOKX Area Forecast Discussion National Weather Service New York NY 842 PM EST Mon Nov 13 2017 .SYNOPSIS... Low pressure passes well to the east tonight and Tuesday as high pressure builds from the west. High pressure retreats to the east on Wednesday as a frontal system approaches from the west. This frontal system moves across the area Wednesday night and Thursday. Another area of high pressure builds in behind it, with another frontal system impacting the area over the weekend. && .NEAR TERM /UNTIL 6 AM TUESDAY MORNING/...
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Mainly clear skies have developed across most of the area tonight. Although some additional lake clouds may rotate in from the north overnight, the downslope should help to erode at least some of them coming off the Catskills. With temperatures already responding to the light winds and clear skies north and west of New York City, low temperatures were adjusted downward. Initial shortwave per mesoscale and global models is progged to pass well to the east tonight, with drier air working its way in from the west. Sfc low pressure will move east as well, with northerly flow behind the system. Enough low level moisture, mainly under 10 kft, remains for a couple of light showers or sprinkles over eastern locales, but generally dry conditions are anticipated tonight. If any light precip does exist, temps may be cool enough for a few snow flakes across interior se CT, if the depth of moisture is adequate to produce snowflakes. Overnight low temperatures will likely range from the mid 20s NW zones, to the mid/upper 30s across NYC metro and Long Island.
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&& .SHORT TERM /6 AM TUESDAY MORNING THROUGH TUESDAY NIGHT/... Next upper shortwave will approach and pass across New England Tuesday, exiting to the east Tuesday night. Not much noted at the sfc as high pressure begins to build from the west. With weak mid and upper level lift Tuesday, areas further east could observe an isolated shower where best available moisture resides. Otherwise, scattered to broken SC clouds are forecast during the day, with some clearing Tuesday night. High temperatures Tuesday will range from the middle to the upper 40s across the region. At night, lows will range from the mid 20s to the mid/upper 30s. Mos blend followed. && .LONG TERM /WEDNESDAY THROUGH MONDAY/... Progressive northern stream across North America through the end of the week, with notable timing differences between the global models with the next wave coming onshore out west Thu/Fri. These differences remain as the trough tracks across the CONUS, and eventually moves across the NE over the weekend. On Wed, ridging at the sfc and aloft slides E of the area with an onshore flow developing. There is good agreement with a shortwave moving through the Great Lakes Wed night and the New England on Thu. This will bring some light amounts of rainfall to the area as a warm front moves through followed by a cold front. Ridging returns behind the cold front later Thu with dry and seasonable weather through Fri. This is where the forecast starts to become uncertain, although the GFS is typically faster to shift the ridge axis east. Thus, have sided with the slower EC and have delayed onset of pcpn to late Fri Night/Sat morning. The GFS is also more amplified as a piece of the polar vortex in northern Canada breaks off with a cutoff low developing over SE Canada over the weekend. At any rate, both are in agreement that the energy from the aforementioned trough moving onshore out west merges with that dropping down from Canada, but timing is off. There is about a 24 hr difference of this occurring between the EC and GFS. It does appear that part of the weekend will be wet (and perhaps some snow inland) and then blustery behind the system into early next week, but way too early for specifics. && .AVIATION /02Z TUESDAY THROUGH SATURDAY/... High pressure remains over the area through Tuesday. VFR tonight except MVFR cigs developing at KGON this evening and possibly at KISP/KBDR by daybreak. For Tuesday, VFR probably prevails from the city terminals to points west. MVFR elsewhere. N winds 5-10 kt through Tuesday. NY Metro Enhanced Aviation Weather Support... Detailed information...including hourly TAF wind component fcsts can be found at: http:/www.weather.gov/zny/n90 KJFK TAF Comments: No unscheduled amendments expected. KLGA TAF Comments: No unscheduled amendments expected. KEWR TAF Comments: No unscheduled amendments expected. KTEB TAF Comments: No unscheduled amendments expected. KHPN TAF Comments: No unscheduled amendments expected. KISP TAF Comments: No unscheduled amendments expected. .OUTLOOK FOR 00Z WEDNESDAY THROUGH SATURDAY... .Tuesday night...VFR. .Wednesday...VFR. SE winds G15-20KT possible at Long Island and CT terminals Wednesday. .Wednesday night-Thursday...MVFR or lower possible in chance of showers. S winds G15-20KT possible at Long Island and CT terminals Wednesday night. W-NW winds G25-30 KT possible Thursday afternoon. .Thursday night-Friday...VFR. NW winds G15-30KT possible, strongest Thursday night. .Saturday... Sub VFR conditions possible by the afternoon and becoming likely towards evening. S-SW Winds 10-15KT with gusts to 25KT. && .MARINE... Gusty northerly winds will continue into this evening as low pressure passes to the east and high pressure builds to the west. After collaboration with surrounding offices, will hold of on SCA for brief gusts 20 to 25 kt before they diminish overnight. Ocean seas should remain 4 feet or less per latest guidance. Again, if SCA conditions are realized, it should be brief. North/northeasterly winds diminish as high pressure nears Tuesday and Tuesday night. Sub-advsy conds expected to prevail into Thu, then increase to SCA levels Thu aftn, perhaps even gales on the ocean Thu night. Elevated seas may linger on the eastern portions of the ocean waters into Fri, but then a brief respite is in store Fri/Fri night with high pressure building across. Increasing winds and building seas then return on Sat as the next frontal system approaches. There is the potential for gales again, but this time could be on all waters. Will highlight the gale potentials in the HWO. && .HYDROLOGY... No hydrologic impacts are expected through Friday. && .EQUIPMENT... KHWV (Shirley/Brookhaven) ASOS temperatures and dew points are about 3 degrees too high. && .OKX WATCHES/WARNINGS/ADVISORIES... CT...None. NY...None. NJ...None. MARINE...None. && $$ SYNOPSIS...24/PW NEAR TERM...12/PW SHORT TERM...PW LONG TERM...24 AVIATION...JC/JE MARINE...24/PW HYDROLOGY...24/PW EQUIPMENT...

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