Area Forecast Discussion
Issued by NWS Upton, NY

Current Version | Previous Version | Text Only | Print | Product List | Glossary On
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 131557 AFDOKX Area Forecast Discussion National Weather Service New York NY 1057 AM EST Mon Nov 13 2017 .SYNOPSIS... An approaching frontal system will have a secondary low passing southeast of Long Island this afternoon and then well out into the Atlantic tonight into Tuesday. High pressure will briefly build into the region Tuesday night into Wednesday morning, then weaken Wednesday afternoon and night. A cold front approaches late Wednesday night and moves across the area on Thursday. High pressure builds into the region on Friday. A storm moving out of the Plains states toward the Great Lakes will send an associated frontal system toward the area, with a strong cold frontal passage Saturday night, followed by blustery and colder conditions on Sunday. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... Minor updates based on radar trends, and temperature trends this morning. Mainly light rain expected, with perhaps some snow or sleet mix inland. Overall, most liquid equivalent is expected to remain near a tenth of an inch or less. Precipitation trends down this afternoon from west to east. Temperatures were a blend of MAV/MET/NAM12/GMOS with highs ranging from the low to upper 40s. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM TUESDAY/... Clouds will linger across Southeast CT and Eastern Long Island tonight into Tuesday. Tuesday, these locations will see a chance of showers, and perhaps for interior Southeast CT, a few snow showers. Temperatures used a MAV/MET/GMOS blend for tonight ranging from upper 20s to upper 30s and MAV/MET/ECS for Tuesday ranging from low to upper 40s mostly. Conditions expected to remain mostly dry. && .LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/... High pressure briefly build across the region Tuesday night into Wednesday morning, then weaken Wednesday afternoon. A cold front will move across the region early Thursday morning, bringing the chance of showers. Light rain could start as early as late Wednesday evening, but the better chance of any showers holds off til after midnight. Winds increase behind the front, setting up for a windy Thursday into thursday night as the pressure gradient tightens up ahead of strong high pressure building out of Canada. This high pressure system builds over the region through Friday, then moves east Friday night. Unsettled weather returns for the weekend as a storm moves out of the Plains states across the Great Lakes and eventually into Quebec late this week into the weekend. There are some model difference between the 00z GFS and 00z ECMWF with the timing of this next system. GFS seems to be slightly quicker, compared to the slower ECMWF. For now, will try and use a model blend for timing. POPs gradually increase Friday night and gradually increase through the day Saturday, with likely POPs by late Saturday into Saturday night with the passage of the cold front. POPs then gradually taper off Sunday morning, with a drier Sunday afternoon. A strong LLJ out ahead of the cold front could help produce moderate to locally heavy showers. Behind the front, expect colder and blustery conditions for Sunday into Monday. At this time, can not rule out some winds possibly approaching advisory levels especially NYC metro and coastal sections. Temperatures through the period should be close to average with highs mostly in the upper 40s and 50s, then turn colder on Sunday with highs only in the 40s. && .AVIATION /16Z MONDAY THROUGH FRIDAY/...
-- Changed Discussion --
High pressure extending along the northeast coast will drift east early this afternoon as a wave of low pressure approaches from the Central Appalachians. The wave of low pressure slides to the south of Long Island late today. High pressure builds to the west into tonight. MVFR conditions with light rain are expected through about 18z for city terminals. MVFR conditions possible at the remainder of the terminals. The rain ends and conditions improve to VFR west to east from around 18-19Z for city terminals, to 20-22Z east. The winds back to N this afternoon up to 10kt. Winds at inland terminals become light and variable late this afternoon/early this evening. 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: Timing of light rain and MVFR conditions ending could be off + 1-2 hours. Low confidence in MVFR conditions. The afternoon KJFK haze potential forecast is yellow...which implies slant range visibility 4-6SM outside of cloud. KLGA TAF Comments: Timing of light rain and MVFR conditions ending could be off + 1-2 hours. Low confidence in MVFR conditions. The afternoon KLGA haze potential forecast is yellow...which implies slant range visibility 4-6SM outside of cloud. KEWR TAF Comments: Timing of light rain and MVFR conditions ending could be off + 1-2 hours. Low confidence in MVFR conditions. The afternoon KEWR haze potential forecast is yellow...which implies slant range visibility 4-6SM outside of cloud. KTEB TAF Comments: Comments: Timing of light rain and MVFR conditions ending could be off + 1-2 hours. KHPN TAF Comments: Comments: Timing of light rain and MVFR conditions ending could be off + 1-2 hours. Low confidence in MVFR conditions. KISP TAF Comments: Timing of light rain and MVFR conditions ending could be off + 1-2 hours. Low confidence in MVFR conditions. .OUTLOOK FOR 12Z TUESDAY THROUGH FRIDAY... .Tuesday... VFR. N winds 5-12KT. .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.
-- End Changed Discussion --
&& .MARINE... Initially tranquil conditions with waves near 1-2 ft and winds less than 10 kt. Expecting an increase in both parameters today into tonight and Tuesday with the development of a secondary low south of Long Island. However, the low is rather weak and as a result, will not substantially increase the pressure gradient between the low moving eastward and a high to the west of the waters. So, expecting conditions to stay mainly below SCA criteria. The ocean seas build to 4 ft and wind gusts reach 20 kt. Both could touch SCA criteria (5ft, 25kt) late today and tonight but with the uncertainty in timing of this and only brief duration exhibited with the 25kt gusts in forecast BUFKIT soundings, decided to hold off on any new SCA issuances. SUB-SCA conditions are expected Tuesday night through early Thursday. SCA conditions are then likely Thursday afternoon into early Fri afternoon as winds increase behind a cold frontal passage. Winds may approach gale force on the ocean Thursday night. Another round of SCA conditions are expected over the weekend with an even stronger cold front moving across the area waters. Winds on the ocean waters may once again approach gale force. && .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...BC/JM NEAR TERM...JM/PW SHORT TERM...JM LONG TERM...BC AVIATION...JE MARINE...BC/JM HYDROLOGY...BC/JM EQUIPMENT...

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