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

000
FXUS61 KOKX 121242
AFDOKX

Area Forecast Discussion
National Weather Service New York NY
742 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 TONIGHT/...
Latest observations show temperatures warmer than forecast
across the area, so any precipitation this morning should fall
as plain rain. Made considerable changes to this morning
forecast update to reflect those conditions.

Otherwise, a 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.

&&

.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 /12Z TUESDAY THROUGH SATURDAY/...
A warm front continues to lift north of the terminals this
morning, followed by a cold front moving across the area this
afternoon and evening.

MVFR ceilings and visibilities develop early this morning as
precipitation moves into the region. It should be warm enough
for the precipitation to fall in the form of plain rain at all
the area terminals.

After the cold frontal passage this afternoon and evening, cold
air will work back into the region and snow showers will be
possible, even at the coastal terminals.

Southerly winds today, 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.
The gusts continue through the evening and into Wednesday
morning, where gusts could reach as high as 40 kt late at the 30
hour TAF sites.

     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 conditions. 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 conditions. 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 conditions. 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 conditions. 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 conditions. 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 conditions. Southerly wind gusts to near 20 KT
possible this morning, then NW gusts 25-30 KT possible this
evening.

.OUTLOOK FOR 12Z WEDNESDAY THROUGH SATURDAY...
.Wednesday...VFR, with a chance of MVFR in snow showers. W-NW
winds G30-40KT possible.
.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.

&&

.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.

&&

$$


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