Area Forecast Discussion
Issued by NWS Upton, NY

Current Version | Previous Version | Text Only | Print | Product List | Glossary Off
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
-- Highlight Changed Discussion --
-- Discussion containing changed information from previous version are highlighted. --
000 FXUS61 KOKX 220557 AFDOKX Area Forecast Discussion National Weather Service New York NY 157 AM EDT Sun Oct 22 2017 .SYNOPSIS... High pressure remains over the region through Monday. Strengthening low pressure heads northward into Southeast Canada Monday night into Tuesday with its associated cold front approaching the region. The cold front will slowly move into the region Tuesday into Tuesday night. The front will become nearly stationary Wednesday before gaining more eastward movement Wednesday night, moving east of the region by early Thursday. An upper level disturbance follows for Thursday before weak high pressure settles in late next week. && .NEAR TERM /UNTIL 6 AM THIS MORNING/...
-- Changed Discussion --
130 AM EDT Update - minor update for recent trends in temps and dew point, otherwise FCST is on track. Patchy / localized radiation fog is likely in the valleys and Pine Barrens, but believe is will not be extensive enough to included in the forecast grids - at least at this time.
-- End Changed Discussion --
&& .SHORT TERM /6 AM THIS MORNING THROUGH 6 PM MONDAY/...
-- Changed Discussion --
High pressure will be situated just offshore with another dry and mostly sunny day as some cirrus filters the sunshine at times. High temperatures will be above normal, but likely a couple of degrees cooler than yesterday in most cases. Low level moisture increases tonight with a light SE flow. Models suggest stratus moving in with better chances of at least a broken deck occurring west of eastern LI and CT. This leads to a partly to mostly cloudy Monday. There appears to be enough isentropic and low level lift for a chance of showers in the afternoon. Showers would be light as mid levels remain dry. Better chances are once again west of eastern LI and CT. In spite of the clouds and onshore flow, highs will still range mostly 70-75.
-- End Changed Discussion --
&& .LONG TERM /MONDAY NIGHT THROUGH SATURDAY/... Deep upper level trough with strong meridional flow will be approaching the region Monday night as the jet dives into the Southeast. The trough will stretch from Florida through Southeast Canada Tuesday into Wednesday. At the surface, the parent low pressure area moves from the Great Lakes Monday night into Northern Quebec by early Wednesday. With all the southerly steering flow, the cold front will have little eastward movement, coming to almost a halt Wednesday before gaining more eastward movement Wednesday night. This will be in response to another upstream diving shortwave that is forecast to move NW to SE from the North Central US into the Carolinas. Thereafter, the upper level trough axis moves across Thursday while the surface cold front moves farther east into the Atlantic. Ridging and high pressure return but will be of lesser magnitude late next week. In terms of weather, rain showers will become more widespread Monday night into Tuesday, lingering into Tuesday night. Bulk of rain expected Tuesday afternoon through Tuesday night. The front nearly coming to a halt Wednesday will keep showers in the forecast Wednesday before tapering off Wednesday night. The region could even still see some showers Thursday with the upper level cold pool associated with the trough axis moving across. Models are hinting at this with their small QPF as the flow becomes more westerly. Then, mainly dry weather is expected Thursday night through next Saturday. Winds could potentially be an issue Tuesday through Tuesday evening. There is a low level jet ahead of the cold front and the models have pretty good agreement with the magnitude being near 50kt Tuesday into Tuesday night. With the deep trough and high precipitable waters forecast, near 1.75 to 1.8 inches, very high (above 90th percentile) for this time of year according to OKX sounding climatology, heavy rain will be possible at times, especially in any thunderstorms. The thunderstorm chances will be there with strong omega and low level instability present within the model guidance. Low level instability is diagnosed from model CAPE fields between 100 and 300 J/kg. S-SE winds of 20-25 mph with gusts 30 to 40 mph are looking more probable especially along the coast with locally higher winds possible with any heavier showers or thunderstorms that could potentially bring down higher winds with downward momentum transport. Temperatures forecast of lower 70s for highs Tuesday and upper 60s to 70 for highs Wednesday. Highs more in the 60s for the rest of the days in the long term. && .AVIATION /06Z SUNDAY THROUGH THURSDAY/...
-- Changed Discussion --
VFR expected through at least 03z Mon with high pres OHD gradually moving east through tonight. There is a low chance of MVFR-IFR fog through 12z at KSWF/KHPN/KGON/KISP. Light and variable winds through the remainder of the night. S/SE winds 8-12 kt develop later this morning and afternoon with seabreeze enhancement at coastal terminals. Aft 03z tonight, the second night of onshore flow, may start seeing indications of fog and/or stratus development, however timing and extent of MVFR/IFR conds is uncertain attm. .OUTLOOK FOR 06Z MONDAY THROUGH THURSDAY... .Late Sun night-Mon...MVFR/IFR possible in stratus and fog into Mon morning, then VFR. S/SE G20 kt Mon aftn. .Mon night-Tue...Potential a period of S/SE G30-40 KT with LLWS SSW 45-55kt@2kft for coastal terminals. Could occur during morning push. MVFR/IFR developing in -RADZ Monday night, continuing with SHRA and low prob/sparse TSRA Tuesday. .Tue night-Wed...IFR possibly continues in showers Tue night...improving to MVFR Wed. .Wed night-Thu...VFR, with iso-sct MVFR in SHRA. W/NW wind.
-- End Changed Discussion --
&& .MARINE... Tranquil conditions on the waters overnight through Sunday night as high pressure ridge with a weak pressure gradient shifts offshore and slowly drifts out to sea. Onshore winds pick up through the day on Monday, but conditions will remain below advisory criteria. SCA conditions become more probable Monday night on the ocean and likely Tuesday through Thursday on the ocean. Gales will be possible Tuesday and Tuesday night, mainly across the ocean with SCA conditions being likely on non-ocean waters. For Wednesday through Thursday, the ocean SCA conditions are mainly due to lingering high seas. && .HYDROLOGY... Localized minor urban flooding will be possible Tuesday into Tuesday night but otherwise no other hydrologic problems are expected with the storm total rain of 1.5 to 2.5 inches mostly falling Monday night through Wednesday. Locally higher amounts will be possible. && .OKX WATCHES/WARNINGS/ADVISORIES... CT...None. NY...None. NJ...None. MARINE...None. && $$ SYNOPSIS...Tongue NEAR TERM...Tongue SHORT TERM...JC LONG TERM...JM AVIATION...24 MARINE...JC/JM/PW HYDROLOGY...JC/JM

USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.