Area Forecast Discussion
Issued by NWS Upton, NY

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FXUS61 KOKX 121737
AFDOKX

Area Forecast Discussion
National Weather Service New York NY
1237 PM EST Tue Dec 12 2017

.SYNOPSIS...
Low pressure passes to the north today moves into the Canadian
Maritimes tonight into Wednesday night. High pressure builds overhead
Wednesday night. An Alberta Clipper will pass through early
Thursday. Developing low pressure will move up the east coast
late Friday into early Saturday. High pressure builds in from
the south Saturday into Sunday, followed by a low pressure
system Sunday night into Monday. High pressure builds back on
Tuesday.

&&

.NEAR TERM /THROUGH TONIGHT/...
Warm front will continue to push north through most of the area
today. Rain is still likely over northern and far eastern
section into early afternoon. Scattered showers otherwise ahead
of an approaching cold front. The cold front arrives late in the
day west of the Hudson River. Winds will be gusty behind it.
High temperatures today above normal.

&&

.SHORT TERM /WEDNESDAY/...
The surface low will move into northern New England and then
into the Canadian Maritimes through Wednesday night as the upper
level low swings through, just north of the area. Colder air
will also move in behind the low. This will change rain back to
snow, from northwest to southeast tonight into Wednesday morning.
However, there will only be a slight chance for precipitation
with no accumulation expected.

As the low pulls away from the area, it will quickly intensify,
allowing for a strong pressure gradient to set up. Conditions
will become windy late tonight into Wednesday, with gusts by
late morning into the afternoon hours of 35 to 45 mph. There may
be an isolated gusts to more than 45 mph, therefore, Wind
Advisory is not needed at this time. Highest winds will occur
across the Twin Forks of Long Island.

Strong cold air advection will continue for Wednesday.
Temperatures not expected to get out of the 20s for inland
areas, with highs around or just above freezing for coastal
areas. Some ocean affect snow showers may find their way inland
for the South Fork of Long Island late Wednesday morning into
the early afternoon before ending by mid afternoon.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/...
Dry, cold and windy conditions expected Wednesday night as high pressure
builds overhead. Temperatures overnight on Wednesday will be in the teens
inland and lower 20s along the coast.

A clipper low will pass south of the area on Thursday bringing a low chance
for snow showers across the area, with only light accumulations expected.
High temperatures on Thursday will be in the upper 20s to lower 30s.

A coastal low is then expected to move up the east coast Friday night and
into early Saturday. How much snow we get from this system depends on how
close the low tracks near the coast. Latest model runs are not in agreement
with timing or position, therefore will continue with chance pops across
the area. A ridge builds in behind the coastal low Saturday into Sunday.
Winds will turn to the southwest, allowing for warmer temperatures across
the area for the weekend.

Low pressure may impact the area later Sunday into Monday...bringing a
chance for precipitation with temperatures on Monday in the upper 30s to
lower 40s.

&&

.AVIATION /18Z TUESDAY THROUGH SUNDAY/...
A cold front passes late this afternoon as low pressure deepens
to the northeast of the area.

Mainly VFR although MVFR possible at times in showers late this
afternoon into the early evening.

Winds shift to the west before 20Z, except a bit later at KGON.
Gusts are possible to 20 kt, then west winds increase after 00Z
15 to 20 kt with gusts 25 to 30 kt. Winds may veer to the
west/NW this evening before settling back to the west overnight.
Gusty westerly winds continue Wednesday morning. Speeds 20 to
25 kt with gusts 30 to 35 kt expected.

    NY Metro Enhanced Aviation Weather Support...

Detailed information, including hourly TAF wind component forecasts,
can be found at: http:/www.weather.gov/zny/n90

KJFK TAF Comments: West/southwest winds gust at times to 20 kt
for the remainder of the afternoon. Gusts however may subside
briefly 20-23Z before increasing after 23-00Z.

KLGA TAF Comments: West/southwest winds gust at times to 20 kt
for the remainder of the afternoon. Gusts however may subside
briefly 20-23Z before increasing after 23-00Z.

KEWR TAF Comments: West/southwest winds gust at times to 20 kt
for the remainder of the afternoon. Gusts however may subside
briefly 20-23Z before increasing after 23-00Z.

KTEB TAF Comments: MVFR ceilings are possible at times for the
remainder of the afternoon. Winds increase after 23-00Z.

KHPN TAF Comments: MVFR ceilings are possible at times for the
remainder of the afternoon. Winds increase after 23-00Z.

KISP TAF Comments: Winds shift to the west/southwest. West winds
increase this evening.

.OUTLOOK FOR 18Z WEDNESDAY THROUGH SUNDAY...
.Wednesday afternoon...VFR. W winds G30-35KT.
.Wednesday night-Thursday morning...MVFR or IFR possible in
snow.
.Thursday afternoon-Friday...VFR. NW wind G15-20 kt into
Thursday night, then winds diminish.
.Friday night...MVFR or IFR possible in snow.
.Saturday...VFR. NW winds G15-20KT possible.
.Saturday night-Sunday...VFR.

&&

.MARINE...
SCA conditions expected over all waters today as
deepening low pressure approaches from the west, increasing the
pressure gradient between the low center and the high center
out into the Atlantic. Cannot rule out a gale gust or two during
the day, but as a front approaches, winds may temporarily
diminish. By nighttime Tuesday, westerly winds pick up behind
the deepening low as it passes north across New England. Waves
will build over all waters. 5 to 7 ft expected over the ocean
waters by the end of the day, and building to 10 to 12 ft over
the ocean waters by the end of the day Wednesday.

Gale Watches have been converted to Warnings as winds will gust
to greater than 34 kt over all waters. Highest winds expected
over the eastern ocean zone, where gusts just over 45 kt
possible by late in the day today. Gale Warning for the ocean
zones starting late tonight, and over all waters for Wednesday.

A Gale Warning remains in effect for all waters Wednesday
night. SCA conditions will likely continue into Thursday morning
for most of area waters. Seas subside below SCA levels by
Thursday night with the pressure gradient weakening and
remaining below SCA conditions through the end of the week. A
coastal storm may then impact the waters Friday night into
Saturday with possible SCA conditions developing.

&&

.HYDROLOGY...
No significant hydrologic impacts expected.

&&

.EQUIPMENT...
NYC NOAA Weather Radio Station KWO-35 (162.55 MHz) is off the
air for an extended period of time.

&&

.OKX WATCHES/WARNINGS/ADVISORIES...
CT...None.
NY...None.
NJ...None.
MARINE...Small Craft Advisory until 6 AM EST Wednesday for ANZ330-335-
     338-340-345.
     Gale Warning from 6 AM Wednesday to 6 AM EST Thursday for
     ANZ330-335-338-340-345.
     Small Craft Advisory until 1 AM EST Wednesday for ANZ350-353-
     355.
     Gale Warning from 1 AM Wednesday to 6 AM EST Thursday for
     ANZ350-353-355.

&&

$$
SYNOPSIS...Fig/JP
NEAR TERM...JC/JP
SHORT TERM...JP
LONG TERM...Fig
AVIATION...PW
MARINE...JC/Fig/JP
HYDROLOGY...Fig/JP
EQUIPMENT...



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