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000
FXUS61 KOKX 220001
AFDOKX

Area Forecast Discussion
National Weather Service New York NY
801 PM EDT Fri Sep 21 2018

.SYNOPSIS...
A cold front approaches and moves across overnight into early
Saturday morning. The front eventually stalls south of Long
Island Saturday into Saturday night. Meanwhile, high pressure
will gradually build in from Southeast Canada and the Great
Lakes. Strong high pressure builds to the north of the area on
Sunday and then offshore early next week. A frontal system will
then impact the area Tuesday into Wednesday, ending with a cold
frontal passage Wednesday night. High pressure follows briefly
for Thursday, before another frontal system impacts the area on
Friday.

&&

.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
Mainly cloudy conditions are expected, and dry weather initially
will give way to increasing chances for showers and
thunderstorms. Breezy S-SW flow will diminish as a cold front
nears.

Showers and thunderstorms with the cold front from a model
consensus conveys they move in during the overnight and then
decrease with southeast movement, making for very little rain
towards the coast. The parent low with the cold front will be
deepening but staying well within Southeast Canada without many
sources of moisture available for the frontal system. There is
some positive vorticity advection across the local area apparent
in the mid levels within the forecast models. Forecast Showalter
Indices indicate some elevated instability, but left
thunderstorm mention as a slight chance in the forecast with
most dynamics staying well northwest of the area. The front
will be moving across during the overnight into early Saturday.

Temps fall into the lower to mid 60s per models, statistical
MOS blend.

&&

.SHORT TERM /6 AM SATURDAY MORNING THROUGH SATURDAY NIGHT/...
In the mid levels, heights will gradually lower Saturday into
Saturday night across the area with a quasi-zonal flow.

At the surface, high pressure will begin to build in from the
Great Lakes Saturday. The local region will be on the eastern
side relative to the center of the high pressure, with thereby
northerly flow during the day to keep dry conditions. The
models have a good consensus on conveying conditions staying dry
through the day and the subsidence from the high pressure will
allow for more sun.

The flow will provide some downslope across coastal locations,
making for adiabatic warming along the coastal areas. The GMOS
was used for max temperatures Saturday, ranging mainly from the
low to mid 70s, relatively warmer at the coast.

The center of the high will remain north and west of NYC and
build more north of the region Saturday night. For Saturday
night, the winds will gain a more easterly component. Meanwhile
though, the cold front that moved across the region will be
slowing down and lingering in the Atlantic Waters to the east of
the Delmarva. The GFS is indicating some return northward of
this front along with some rain late Saturday night into very
early Sunday morning with more easterly flow for the local area
but other models are farther southward, maintaining dry
conditions across the local area. Kept a dry forecast for the
local area Saturday night.

For min temperatures Saturday night, used a blend of MAV/ECS
guidance which was relatively warmer than other guidance with
more clouds mitigating radiational cooling.

There is a moderate risk for the development of rip currents at the
ocean beaches Saturday morning, with a low risk in the afternoon as
winds diminish and seas subside.

&&

.LONG TERM /SUNDAY THROUGH FRIDAY/...
A confluent flow across eastern Canada and the northeast will
allow for strong high pressure to pass to the north through
Monday. There is some concern with a frontal wave associated
with a shearing mid-level shortwave trough, but will maintain a
dry forecast on Sunday with some morning clouds mainly near the
coast. Any light rain should stay south of Long Island. The GFS
which does produce some measurable rain across the NYC metro
and Long Island appears to be overdone based on the depth of
dry air and the northern placement of the upper jet in
comparison to the model consensus.

The weather then takes a downhill swing for the midweek as an
upper trough out west races eastward with a frontal system
impacting the area Tuesday into Wednesday. First of which will
be with overrunning rain Monday night into Tuesday night and
then with scattered convection on Wednesday. The cold front
follows Wednesday night. Additional timing issues have now risen
with the GFS trending against the model suite by stalling the
front Wednesday night into Friday, with multiple waves of low
pressure riding along the front. In this scenario, the kicker
will be with a late week cold frontal passage. All the global
models support the late week kicker, the differences though
arise with the lead shortwave trough lifting out to the NE
Wednesday night into Thursday. The magnitude of this feature
and its wavelength separation with the next upper trough/surface
frontal system, will determine whether the first boundary makes
it through. Even the GGEM which sends the first front east of
the area Wednesday night, is close enough for a coastal low to
impact the area Thursday night into Friday. Thus, there remains
quite a bit of uncertainly for the Thursday into Friday
timeframe and have maintained a low chance for rain at this
time.

Seasonable temperatures will start the week, but it then gets
warm and humid Wednesday in the warm sector. The end of the week
is a bit tricky depending on the placement of the aforementioned
frontal boundary.

&&

.AVIATION /00Z SATURDAY THROUGH WEDNESDAY/...
A cold front passes through late tonight, then high pressure
returns on Saturday.

Mostly VFR to MVFR. Chance of showers late. VFR follows behind
the cold front early Saturday morning.

S winds gusting up to 20 kt, becoming SW by midnight, then
shifting NW behind the cold front late at night. N winds on
Saturday gusting up to around 20 kt in the morning, with gusts
subsiding in the afternoon.

     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: Tempo MVFR cigs possible before 03z. Gusts
might be only occasional.

KLGA TAF Comments: Tempo MVFR cigs possible before 03z. Gusts
might be only occasional.

KEWR TAF Comments: Tempo MVFR cigs possible before 03z.

KTEB TAF Comments: Tempo or VFR possible this evening.,

KHPN TAF Comments: Tempo VFR possible this evening.

KISP TAF Comments: Brief periods of MVFR cigs possible into
this. Gusts might be only occasional.

.OUTLOOK FOR 00Z SUNDAY THROUGH WEDNESDAY...
.Saturday night-Sunday...VFR.
.Monday...VFR.
.Tuesday and Wednesday...MVFR or lower in showers. SE Gusts 25
kt on Tuesday.

&&

.MARINE...
Increasing winds and seas will lead to SCA conditions tonight
for all waters. Non-ocean waters will remain below SCA for seas
but winds will gust to SCA levels. The ocean will observe
increasing seas to 4 to 6 ft. The SCA conditions linger into
Saturday just for the ocean as the seas will have some long
period swell that keep seas elevated a little longer. SCA seas
remain on the ocean until 18Z Saturday. Thereafter through the
remainder of the weekend, local waters will drop to below SCA
level conditions.

Easterly winds strengthen Monday into Monday night and continue
into Tuesday ahead of an approaching warm front. SCA conditions
are likely to develop during this time with a small chance of
gale force gusts on the ocean waters. High seas likely linger
into Wednesday with a southerly flow as the warm front passes to
the north and a cold front approaches late in the day.

&&

.HYDROLOGY...
No significant widespread rain expected through early Saturday.
Total average rainfall expected to remain less than a quarter
of an inch. Dry weather is then forecast for the rest of
the weekend.

A frontal system could bring locally heavy showers/tstms Tue
into Wed, first via warm fropa on Tue, then again via trailing
cold fropa on Wed. Anticipate only localized nuisance impacts at
this early point.

&&

.EQUIPMENT...
NYC NOAA Weather Radio Station KWO-35 (162.55 MHz) remains 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 EDT Saturday for ANZ330-335-
     338-340-345.
     Small Craft Advisory until 2 PM EDT Saturday for ANZ350-353-
     355.

&&

$$
SYNOPSIS...JM/DW
NEAR TERM...JM/PW
SHORT TERM...JM
LONG TERM...DW
AVIATION...JC
MARINE...JM/DW/PW
HYDROLOGY...JM/DW
EQUIPMENT...