Area Forecast Discussion
Issued by NWS Upton, NY

Current Version | Previous Version | Graphics & Text | 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 092139 AFDOKX Area Forecast Discussion National Weather Service New York NY 439 PM EST Sat Dec 9 2017 .SYNOPSIS...
-- Changed Discussion --
Low pressure will pass southeast of Long Island tonight, and head into the Canadian Maritimes through Sunday morning. Weak high pressure will then build across from Sunday into Monday. Low pressure moving across the Great Lakes Monday night and passing north on Tuesday will weaken, while a second low develops nearby and intensifies while moving into the Canadian Maritimes through Thursday. Another low may impact the area from late Thursday into Friday, followed by high pressure on Saturday.
-- End Changed Discussion --
&& .NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
-- Changed Discussion --
A northern stream shortwave trough pushes into the area tonight. This coupled with the associated coastal low and the region being in the right rear quadrant of an around 200 kt 250 hPa jet will allow for snow to continue across the entire CWA for most of this evening, then taper off from SW to NE through the overnight hours. The exception is over the S fork of Long Island, where some mixing is possible until probably 1-2z - when the low level warm nose should retreat to the east - offshore. In addition, with light precipitation currently over most of Long Island, would not be surprised if saw a report of two of ice pellets over the next couple of hours before the next surge of snow. However, this should be fairly transitory and not long lived in any given location, so lack of confidence in occurrence/location precludes including in the official forecast at this time. Do have some concern about a fairly persistent band of snow stretching from NE NJ into SW CT. There are some signs its beginning to shear out, but if it maintains itself, would not be surprised to see a few reports of 6-7+ inches under the band. Have taken that segment of the advisory, upped totals to 4-6 inches and added the phrase locally higher amounts possible to reflect this potential. However, if this band does not end up weakening within the next couple of hours, will need to strongly consider expanding the Winter Storm Warning westward to cover the area under the band. Otherwise, the snow forecast and headlines remain mainly unchanged, with a winter storm warning for SE CT/S New Haven County and all but SE Suffolk County (5-7 inches of snow) and a winter weather advisory for the remainder of the CWA (2-6 inches of snow - lowest amounts on far eastern portions of the S fork of Long Island, with mainly 3-6 inches elsewhere - except as noted in the previous paragraph. Temperatures will continue to slowly fall tonight, with lows generally 3-5 degrees below current readings.
-- End Changed Discussion --
&& .SHORT TERM /6 AM SUNDAY MORNING THROUGH SUNDAY NIGHT/...
-- Changed Discussion --
The northern stream shortwave trough exits to the NE Sunday, and other than possibly some lingering light snow over SE CT/Twin Forks Sunday morning, it should be dry on Sunday with decreasing cloud cover. It should be brisk on Sunday with a brisk W wind with gusts of 15-30 mph, strongest over NYC/Long Island. Another northern stream shortwave trough approaches Sunday night. Will see increasing cloud cover ahead of it. Cannot rule out some flurries late Sunday night over mainly over western zones ahead of the shortwave trough, however confidence in this is not quite high enough to reflect in the forecast at this time.
-- End Changed Discussion --
&& .LONG TERM /MONDAY THROUGH SATURDAY/...
-- Changed Discussion --
A relatively active/progressive pattern will continue this week, with one low pressure system likely impacting the area Mon night into Tue morning, and perhaps another from late Thu into Fri. Most of the precip with the first system should occur on the front end via warm advection, with all snow inland, and snow changing to rain closer to the coast. Amounts should be on the light side, with about an inch closer to the coast, and 2 or 3 inches inland. Temps Tue morning as a triple point low develops nearby Tue morning should rise to the upper 30s/lower 40s, then as this low moves into the Canadian Maritimes and intensifies, blustery and colder conditions expected for Tue night through Wed night, with lows in the teens and 20s, and low from the mid 20s to lower 30s. Some uncertainty exists on the timing and track of one or more northern stream disturbances for late week. The 00Z ECMWF tracked a leading clipper low just off to the south, while the 12Z tracked the same low well south. Models generally agree on another more consolidated system passing through late Thu night into Friday as an amplifying long wave upper trough to the west approaches and passes through. As a result have broad- brushed low chance PoP from Thu night into Friday. Temps should be cold enough for precip with this potential system to be mainly snow. After this low passes, zonal flow should return, with temps returning closer to average, if not on Sat, then early next week before the trough reloads and colder air returns mid next week.
-- End Changed Discussion --
&& .AVIATION /20Z SATURDAY THROUGH THURSDAY/...
-- Changed Discussion --
Low pressure passes to our SE early this evening, and moves into the Canadian Maritimes late tonight. IFR and snow through the earlier evening hours, improving to MVFR towards midnight, then VFR late tonight except east of the city. Snow may end a couple hours earlier than indicated in TAFs. North flow generally below 12 kt during the afternoon and evening. Winds back towards NW overnight, then bcmg W on Sunday with gusts around 20 KT. Terminal Snowfall Forecast: KJFK: Snowfall rates could reach 1 inch per hour. 4-6 inches of total snow forecast. KLGA: Snowfall rates could reach 1 inch per hour. 4-6 inches of total snow forecast. KEWR: Snowfall rates could reach 1 inch per hour at times. 5-6 inches of total snow forecast. KTEB: Snowfall rates could reach 1 inch per hour at times. 5-6 inches of total snow forecast. KHPN: Snowfall rates could reach 1 inch per hour at times. Around 6 inches of total snow forecast. KISP: Snowfall rates could exceed 1 inch per hour at times. Sleet will be possible until 23-00z. Around 5-6 inches of total snowfall forecast. .OUTLOOK FOR 18Z SUNDAY THROUGH THURSDAY... .Sunday...VFR. W gusts around 20 kt. .Monday...VFR. Iso flurries in the morning. .Tuesday...MVFR or lower with early morning mixed pcpn, changing to rain by mid-morning. Dry aftn with CHC VFR by late. .Wednesday...VFR, chc MVFR/-shsn east of city terminals. NW gusts 30-35 kt. .Thursday...VFR
-- End Changed Discussion --
&& .MARINE...
-- Changed Discussion --
SCA in effect for all waters, first on the ocean tonight as winds back NW after passage of offshore low pressure, with seas building to 5-8 ft and winds gusting up to 25 kt, then on all waters Sunday into Sunday night as winds back W and gust to 25-30 kt. These conditions should linger on the ocean into Monday as an upper level disturbance passes across. Low pressure developing nearby on Tue should strengthen on its way to the Canadian Maritimes, with SCA developing daytime Tue on the ocean waters. As the low intensifies, gales are likely on the ocean Tue night and on all waters Wed into Wed night. Gales could linger on the eastern ocean waters into Thu morning, otherwise SCA conds expected daytime Thu, with quiet conds returning Thu night as the Maritimes low loses its influence.
-- End Changed Discussion --
&& .HYDROLOGY...
-- Changed Discussion --
Around 0.2 to 0.5 inches of additional liquid equivalent QPF expected through tonight. With this mainly if not entirely in the form of snow, no significant hydrologic impacts expected. No hydrologic impacts are anticipated thereafter.
-- End Changed Discussion --
&& .EQUIPMENT...
-- Changed Discussion --
NYC NOAA Weather Radio Station KWO-35 (162.55 MHz) is off the air for an extended period of time. See our headline news on the web at: http:/weather.gov/nyc The Riverhead NOAA Weather Radio Station WXM-80 (162.475 MHz) is currently out of service. NWS technicians are working with Verizon to restore service. An estimated time of return to service is not currently known.
-- End Changed Discussion --
&& .OKX WATCHES/WARNINGS/ADVISORIES...
-- Changed Discussion --
CT...Winter Storm Warning until 6 AM EST Sunday for CTZ007-008- 010>012. Winter Weather Advisory until 4 AM EST Sunday for CTZ005-006- 009. NY...Winter Storm Warning until 6 AM EST Sunday for NYZ078>080. Winter Weather Advisory until 1 AM EST Sunday for NYZ067>069. Winter Weather Advisory until 4 AM EST Sunday for NYZ070>075- 176>179. Winter Weather Advisory until 6 AM EST Sunday for NYZ081. NJ...Winter Weather Advisory until 1 AM EST Sunday for NJZ002-004- 103-105-107. Winter Weather Advisory until 4 AM EST Sunday for NJZ006-104- 106-108. MARINE...Small Craft Advisory from 6 AM to 6 PM EST Sunday for ANZ335- 338-345. Small Craft Advisory from 6 AM Sunday to 6 AM EST Monday for ANZ330-340. Small Craft Advisory until 6 PM EST Monday for ANZ350-353-355.
-- End Changed Discussion --
&& $$ SYNOPSIS...Maloit NEAR TERM...Maloit SHORT TERM...Maloit LONG TERM...Goodman AVIATION...JC MARINE...Maloit/Goodman HYDROLOGY...Maloit/Goodman EQUIPMENT...

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