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
000
FXUS61 KOKX 161732
AFDOKX

Area Forecast Discussion
National Weather Service New York NY
1232 PM EST Thu Nov 16 2017

.SYNOPSIS...
A weak wave of low pressure moves through the area today,
followed by a cold front tonight. High pressure briefly builds
through late week before another strong low pressure system
impacts the area this weekend. High pressure once again builds
to the south for early week, followed by a cold front by mid
week.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
Latest update accounted for breaks in the sky cover across
Northern New Jersey into Nassau County. Any showers over the
Twin Forks of Long Island and New London County in Connecticut
will be moving out within the next hour or so.

Drier air will be advecting in this afternoon ahead of a cold
front. Have adjusted temperatures up a degree or two with this
update to account for clearing, however temperatures are not
expected to rise much this afternoon.

It is possible that a brief shower or two will accompany the
frontal passage this afternoon as low-level instability
increases. Both the HRRR and the NAM Nest show the possibility
of showers developing across the Lower Hudson Valley and
northern NJ in the 20-21Z timeframe.

Mainly SW winds expected through early this afternoon before
veering to the W late this afternoon as the cold front moves
through. Gusts 20-25 kt this afternoon, increasing a few knots
into tonight as the winds shift more northwesterly.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM FRIDAY/...
Despite clearing skies and the advection of a cooler continental
polar air mass, winds will remain strong through much of the
night which will likely hinder temperatures from falling too far
below normal. Should winds subside sooner than forecast,
particularly across the lower Hudson Valley, seasonably cool
temperatures may be possible overnight.

The pressure gradient will remain tight through much of the day
as the low departs into eastern Canada and high pressure builds
to the west. Temperatures will be close to normal to a few
degrees below, with dry conditions and mostly sunny skies as dry
air advects southeastward.

&&

.LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/...
A progressive upper flow will continue into next week. That
being the case, there will be multiple interactions with short
waves between the polar branches for brief amplification. The
first being with jet energy interaction between the southern
and northern branches Saturday night into Sunday across the
Great Lakes region. This results in the formation of a negatively
tilted upper trough/closed low lifting across eastern Canada
Sunday into Monday.

At the surface, a strong cold front works through the region
Sunday morning. Preference continues to be toward the slightly
slower ECMWF and GGEM, with the GFS having trended in that
direction over the last couple of day. Both pre- and post-
frontal winds could gusts up to 40 mph Saturday afternoon
through Sunday. While there will be decent warm advection ahead
of the system Saturday, dry low-levels will likely limit
coverage of any precipitation. Best lift and heaviest rainfall
likely comes overnight Saturday along and ahead of the cold
front with the potential for up to half an inch. There is some
weak elevated instability, so an isolated rumble of thunder is
possible. Higher rainfall amounts are possible should the
system close off sooner.

Deepening low pressure tracking across eastern Canada Sunday
into Monday and high pressure building to the southwest will
result in a prolonged period of gusty west winds.

Another fast moving frontal system approaches on Tuesday and
passes through on Wednesday. Latest ECMWF is more amplified and
somewhat slower than the GFS. GGEM is even slower. Model
consensus was followed at this juncture in time.

Temperatures will fluctuate through the period with multiple
frontal boundaries in the fast flow. It will be above normal
Saturday into Saturday night, then trending down Sunday into
Monday behind the departing storm over eastern Canada.

&&

.AVIATION /18Z THURSDAY THROUGH TUESDAY/...
A cold front crosses the terminals today with an area of low
pressure intensifying as it tracks up the New England Coast.
High pressure builds to the west tonight into Friday.

VFR forecast through the TAF period. A few scattered showers
are possible this afternoon as the cold front moves across.
Mention of the showers is currently not in the TAF, but they
should quickly move through 18-19z across the Lower Hudson
Valley, and 19-21z across NYC, Long Island, and southern
Connecticut.

Winds will continue veering to the W and then WNW this afternoon
and evening. Gusts 20-25 KT are expected this afternoon
increasing to 25-30 KT this evening and tonight. Occasional
peak gusts to 35 kt are possible this evening. WNW winds
continue on Friday with gusts continuing.

     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: Wind direction likely to stay left of 310
magnetic through this evening. Timing of stronger gusts may be
off by a few hours. A brief shower is possible 19-21z.

KLGA TAF Comments: Wind direction likely to stay left of 310
magnetic through this evening. Timing of stronger gusts may be
off by a few hours. A brief shower is possible 19-21z.

KEWR TAF Comments: Wind direction likely to stay left of 310
magnetic through this evening. Timing of stronger gusts may be
off by a few hours. A brief shower is possible 19-21z.

KTEB TAF Comments: Timing of stronger gusts may be off by a few
hours. A brief shower is possible 19-21z.

KHPN TAF Comments: Timing of stronger gusts may be off by a few
hours. A brief shower is possible 19-21z.

KISP TAF Comments: Timing of stronger gusts may be off by a few
hours. A brief shower is possible 20-22z.

.OUTLOOK FOR 18Z FRIDAY THROUGH TUESDAY...
.Friday Afternoon...VFR. NW winds G25KT.
.Saturday...MVFR or lower conditions possible by the afternoon
and becoming likely towards evening. Showers at night S-SW
winds G25-35KT.
.Sunday...Conditions improve to VFR with showers ending. NW
winds G25-30KT.
.Monday-Tuesday...VFR. NW winds 20-25KT.

&&

.MARINE...
Winds will rapidly strengthen behind a frontal system today,
allowing seas to build into Friday as the pressure gradient
remains tight. These winds will strengthen to gales by tonight
and continue into much of Friday before subsiding from west to
east as high pressure builds into the area.

A brief quiet period expected Fri night into Sat morning, then
S-SW winds should quickly ramp up on the ocean waters Sat
afternoon and on the remaining waters Sat night. Winds on the
ocean waters may gust close to gale force Sat night ahead of an
approaching cold front.

Gales are likely on all waters on Sunday after the cold frontal
passage, followed by an extended period of SCA conditions Mon into
Mon night.

&&

.HYDROLOGY...
A quarter to three quarters of an inch of rain is expected
across eastern Long Island and southeast Connecticut this
morning, with lesser amounts further west.

There is the potential for around half an inch of rainfall
Saturday night along and ahead on approaching cold front.

&&

.OKX WATCHES/WARNINGS/ADVISORIES...
CT...None.
NY...None.
NJ...None.
MARINE...Small Craft Advisory until 6 PM EST this evening for ANZ330-
     335-338-340-345.
     Gale Warning from 6 PM this evening to 6 AM EST Friday for
     ANZ330-335-338-340-345.
     Small Craft Advisory until 6 PM EST this evening for ANZ350-
     353-355.
     Gale Warning from 6 PM this evening to noon EST Friday for
     ANZ353-355.
     Gale Warning from 6 PM this evening to 6 PM EST Friday for
     ANZ350.

&&

$$
SYNOPSIS...CB/MD
NEAR TERM...CB/MD
SHORT TERM...MD
LONG TERM...DW
AVIATION...BC/DS
MARINE...MD/DW
HYDROLOGY...CB/MD/DW



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