Area Forecast Discussion
Issued by NWS Upton, NY

Home | 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
000
FXUS61 KOKX 120916
AFDOKX

Area Forecast Discussion
National Weather Service New York NY
416 AM 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 TODAY/...
The near term will feature a trough over the eastern half of the
U.S. in the upper levels. At the same time, low pressure will
approach from the eastern Great Lakes region and head east,
passing north of the area. Chances for precipitation will
therefore increase through the morning, then decrease this
afternoon as the low heads away from the area.

As for precipitation types, enough cold air will remain well
inland for precipitation to start as all snow, mainly for
portions of northeast New Jersey and northern portions of the
Lower Hudson Valley. There remains a decent spread in
temperature and dew point for evaporational cooling to lower
temperatures once the steadier precipitation moves in.
Elsewhere, such as inland Connecticut, it may start as a mix of
rain and snow, while coastal areas will see all rain to start
out. The rain/snow line will lift north of the area from 14-16Z
today.

With the low passing well to the north, much of the forcing will
occur outside of our area, and thus, much of the heavier QPF
will remain north. Up to a quarter of an inch for northern
portions of the area, with only a few hundredths for southern
areas. Snow amounts will be light as well, a dusting for most
areas that see snow, with isolated areas receiving 1 to 2
inches, mainly across western Orange County.


&&

.SHORT TERM /TONIGHT THROUGH 6 PM 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 /08Z TUESDAY THROUGH SATURDAY/...
Low pressure from the eastern Great Lakes to the Ohio Valley will
bring a warm front through the terminals early this morning. As the
low moves into northern New England, a cold front will move through
during the afternoon.

MVFR ceilings and visibilities develop early this morning as
precipitation, mainly light rain, becomes steady. The only exception
is at KSWF where a period of snow, then a rain/snow mix is likely.
There is now more confidence in rain at the terminals as warm air
moves in ahead of the cold front.

After the cold frontal passage snow showers will be possible,
even at the coastal terminals.

Southerly winds develop behind the warm front, then shift to
the west to northwest behind the cold front, and become gusty.
There is the potential for winds to gust as high as 30 KT,
especially during the evening.

...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: Amendments may be possible today to fine tune
timing of MVFR and any precipitation this morning. Southerly wind
gusts to near 20 KT possible this morning, then NW gusts 25-30 KT
possible this evening.

The afternoon KJFK haze potential forecast is GREEN...which implies
slant range visibility 7SM or greater outside of cloud.

KLGA TAF Comments: Amendments may be possible today to fine tune
timing of MVFR and any precipitation this morning. Southerly wind
gusts to near 20 KT possible this morning, then NW gusts 25-30 KT
possible this evening.

The afternoon KLGA haze potential forecast is GREEN...which implies
slant range visibility 7SM or greater outside of cloud.

KEWR TAF Comments: Amendments may be possible today to fine tune
timing of MVFR and any precipitation this morning. Southerly wind
gusts to near 20 KT possible this morning, then NW gusts 25-30 KT
possible this evening.

The afternoon KEWR haze potential forecast is GREEN...which implies
slant range visibility 7SM or greater outside of cloud.

KTEB TAF Comments: Amendments may be possible today to fine tune
timing of MVFR and any precipitation this morning. Southerly wind
gusts to near 20 KT possible this morning, then NW gusts 25-30 KT
possible this evening.

KHPN TAF Comments: Amendments may be possible today to fine tune
timing of MVFR and any precipitation this morning. Southerly wind
gusts to near 20 KT possible this morning, then NW gusts 25-30 KT
possible this evening.

KISP TAF Comments: Amendments may be possible today to fine tune
timing of MVFR and any precipitation this morning. Southerly wind
gusts to near 20 KT possible this morning, then NW gusts 25-30 KT
possible this evening.

.OUTLOOK FOR 06Z WEDNESDAY THROUGH SATURDAY...
.Tuesday night-Wednesday...VFR, with a chance of MVFR in snow
showers. W-NW winds G20-30KT probable.
.Wednesday night-Thursday night...VFR. W-SW winds G15-25KT possible.
.Friday...MVFR possible with snow. W-NW winds G15-20KT possible.
.Saturday...VFR. NW winds G15-20KT possible.

&&

.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. 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.

&&

.OKX WATCHES/WARNINGS/ADVISORIES...
CT...None.
NY...None.
NJ...None.
MARINE...Gale Watch from Wednesday morning through late Wednesday night
     for ANZ330-335-338-340-345.
     Small Craft Advisory from 6 AM this morning to 6 AM EST
     Wednesday for ANZ330-335-338-340-345.
     Gale Watch from this evening through late Wednesday night for
     ANZ350-353-355.
     Small Craft Advisory from 6 AM this morning to 6 PM EST this
     evening for ANZ350-353-355.

&&

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


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