000
FXUS61 KOKX 160545
AFDOKX

Area Forecast Discussion
National Weather Service New York NY
1245 AM EST Sat Jan 16 2021

.SYNOPSIS...
Low pressure develops along an approaching warm front. The low
then moves then up into Central and Northern New England
Saturday afternoon into Saturday night. Thereafter, a series of
cold fronts will then move across the area through the middle of
next week, each followed by weak high pressure.

&&

.NEAR TERM /THROUGH TODAY/...
A strong upper level low continues to approach the eastern
seaboard tonight. A parent low pressure is slowly weakening over
the Great Lakes as secondary low pressure development is
beginning to take place over the Middle Atlantic coast along a
warm front. A strengthening low level jet between 2 and 8kft
overnight of 55 to 65 kt will allow for bands of moderate to
locally heavy rain as the low begins to deepen with the approach
of the warm front.

One area of rain has already lifted through the region with
other bands beginning to lift northward from along and off the
NJ coast. The secondary low will deepen through Saturday
morning, moving mainly over eastern Long Island and southeast
Connecticut. Large scale lift will also increase through the
morning hours as height falls in advance of the upper low. The
eastern portion of the region becomes situated within strong
divergence aloft ahead of an upper jet rounding the base of the
trough.

There is excellent agreement among the high resolution models
for a band of heavy rain to develop as the low deepens and the
frontal system begins to move through. The location of the
heaviest rain within this band looks to occur across eastern
Long Island and southeast Connecticut around 08-13z. The system
as a whole will move through relatively quickly, but deep
moisture will allow for moderate rain at times even west of the
heaviest band. Rainfall amounts of one half to one inch are
forecast from NYC on west and one to two inches further east,
highest across eastern Long Island and southeast Connecticut.
Have also included isolated thunder overnight into the early
morning hours.

A stable boundary layer will preclude any of the high winds from
making it to the surface, but gusts 30-40 mph cannot be ruled
out closest to the coasts.

Rain decreases in intensity west to east Saturday morning but
cloudy conditions will prevail and periodic rain showers could
linger around. The local region will still be east of the upper
level low and in a region of positive vorticity advection. Winds
will be lighter with the surface low developing across the front
Saturday morning with a decrease in pressure gradient. As the low
passes to the northeast into Central New England Saturday
afternoon, the pressure gradient will tighten again with more of a
SW to eventually W flow developing as the low moves farther
northeast and deepens. Gusts will redevelop mid to late Saturday
afternoon.

The highs Saturday were a blend of NBM and CONSRaw, mainly in the
mid to upper 40s.

&&

.SHORT TERM /TONIGHT THROUGH 6 PM SUNDAY/...
For Saturday night, the low will continue to deepen as it moves into
Northern New England. The upper level low moves northeast of the
region, with the flow becoming more zonal by early Sunday. Other
than a few showers, mainly dry conditions are anticipated. The
showers could be both rain and snow showers with colder air
advecting in and accounting for wet bulb cooling.

Winds will be W and gusty and the well mixed boundary layer will
allow for relatively warmer temperatures. Lows Saturday night were a
blend of NBM and CONSAll and range from the upper 20s to lower
30s.

&&

.LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/...
The northern branch of the polar jet will remain dominant across the
NE quarter of the country through the upcoming week. This will
largely result in dry, seasonably cold weather during this period.

As the onset, the cutoff upper low will be lifting northward on
Sunday into the Canadian maritimes in conjunction with deep surface
low pressure (around 980 mb). This will keep the area under gusty
west winds (up to 35 mph) with partly to mostly sunny conditions. A
series of strong shortwave troughs will then follow through the
middle of next week, one early Monday, and another early Wednesday.
While there is limited moisture available, a chance of flurries
and/or a snow shower can not be ruled out. The later shortwave will
be followed by the coldest shot of air during the period with
temperatures struggling to get much above freezing on Wednesday.
Global models are at odds with the magnitude of this features and
the associated cold air.
Taking a middle road approach will still keep high in the 30s. This
coupled with another day of gusty winds will keep wind chill values
in the 20s.

Another northern branch shortwave will send low pressure pressure
tracking north of the Great Lakes on Thursday,sending a warm front
through the region. The operational ECMWF develops a frontal wave
near the Delmarva which tracks to the south and east, passing near
the benchmark. This scenario raises the potential for some wintry
weather, but many of the global models are progressive with this
system and don`t form a coastal low. For the time, chances of
precipitation will remain low. A large area of high pressure then
builds in for the end of the period.

&&

.AVIATION /06Z SATURDAY THROUGH WEDNESDAY/...
Low pressure develops in the vicinity New York City tonight and
tracks northeast during the day Saturday.

As the rain moves in, any MVFR conditions lower to IFR with a chance
of LIFR in rain and fog.

Easterly winds increase to 15 to 20 kt with gusts up to 30 kt. Some
gusts may briefly exceed 30 kt, especially east of the NYC
terminals. There will be a lull (or at least a speed reduction) in
the winds towards daybreak as the low develops along the cold front.
Then SE to S winds increase again as the low begins to track to the
northeast. Winds shift to the SW late in the TAF period. Chance of
some level wind shear at KBDR and KISP, but more likely at KGON
toward 10Z as a low level jet 50 to 60 kt develops.

  NY Metro (KEWR/KLGA/KJFK/KTEB) TAF Uncertainty...

Amendments are expected in varying conditions. Chance of TS at any
one location is low but possible.

.OUTLOOK FOR 18Z SATURDAY THROUGH WEDNESDAY...
.Saturday...MVFR, possibly IFR in the morning, with rain, becoming
less widespread in the afternoon. Rain ends late afternoon into the
early evening, possibly ending as a rain/snow mix well north and
west of the New York City terminals. SW-W wind gusts near 15-20 kt.
.Sunday...VFR. W wind gusts 25-30 kt. Gusts diminish at night.
.Monday...VFR. W wind gusts 15-20 kt, mainly during the day.
.Tuesday...VFR.
.Wednesday...Mainly VFR, chance of MVFR.

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

&&

.MARINE...
Low level jet developing will be moving across eastern ocean waters
tonight bringing gale force gusts. There could be an occasional
gust to gale force on the waters west of Fire Island Inlet, but
otherwise the low level jet passes east keeping SCA range for
winds. This holds true for the Western Sound and NY Harbor as
well.

There will be a lull in winds early Saturday before picking up
again late Saturday into Saturday night as the low moves
northeast of the region and deepens, tightening the pressure
gradient. Gales will be possible late Saturday night, with
otherwise widespread SCA level gusts.

Ocean seas will stay in a 5 to 8 ft range through Saturday night.
Eastern Long Island Sound has a 3 to 5 ft range through Saturday
night.

A prolonged period of SCA conditions can be expected on most waters
from Sunday into Tuesday as a series of cold fronts move through the
waters, followed by gusty west winds.

&&

.HYDROLOGY...
A low pressure system is expected to bring up to 1 - 1.5 inches
of rainfall tonight into Saturday morning with locally higher
amounts possible. Flash flooding is not anticipated due to the
relatively fast motion of the storm and antecedent dry
conditions. Minor urban street and poor drainage flooding
however will still be possible.

No significant precipitation is expected thereafter.

&&

.TIDES/COASTAL FLOODING...
A few sites will reach their minor coastal flood benchmarks in
the South Shore Bays Saturday morning and parts of southern Westchester
NY and coastal Fairfield CT overnight during their respective
high tide cycles. The statement may need to be expanded westward
across the Lower Harbor. Wind forcing will increase surge to
around 1 to 2 ft above astronomical water levels.

&&

.OKX WATCHES/WARNINGS/ADVISORIES...
CT...None.
NY...None.
NJ...None.
MARINE...Small Craft Advisory until 6 AM EST early this morning for
     ANZ335-338.
     Gale Warning until 6 AM EST early this morning for ANZ330-340-
     345-350-353.
     Small Craft Advisory until 6 PM EST this evening for ANZ355.

&&

$$
SYNOPSIS...JM/DW
NEAR TERM...JM/DS
SHORT TERM...JM
LONG TERM...DW
AVIATION...IRD/MW
MARINE...JM/DW
HYDROLOGY...JM/DW
TIDES/COASTAL FLOODING...

NWS OKX Office Area Forecast Discussion