000
FXUS61 KOKX 272353
AFDOKX
Area Forecast Discussion
National Weather Service New York NY
753 PM EDT Sun Aug 27 2023
.SYNOPSIS...
High pressure building over the area slides to the east Monday
afternoon. A stationary front northwest of Tropical Cyclone
Franklin, which will stay well south and east of the area,
briefly backs up toward the east coast Monday night into
Tuesday. A cold front moves through Wednesday, followed by high
pressure building in for the end of the week.
&&
.NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
-- Changed Discussion --
Scattered showers were continuing across SE CT, being triggered
by an area of enhanced low-level convergence provided by a
stalled out seabreeze. In addition, there was an upper trough
passing through with marginal instability. The convection is all
low-topped, but at times having high reflectivity. While there
is 40kt of deep-layer shear, winds in the steering level are
weak resulting in a slow storm motion. There have been pockets
of an inch of rainfall in an hours time. Expect this area to
dissipate with the loss of heating, weakening convergence, and
departure of the shortwave trough.
As high pressure centers itself north of the area tonight, a weak
onshore easterly flow develops over the area. This will enhance low
level moisture advection. As generally clear skies cool temps into
the 60s tonight, there is a potential for some fog development,
especially for cooler spots and along the coast.
While there doesn`t appear to be much in the way of forcing, a few
spotty patches of drizzle or very light showers will be possible.
This is especially true for portions of the Lower Hudson Valley as
we approach the morning hours on Monday as an area of showers forced
by weak warm air advection on the backside of the departing high,
may approach the area.-- End Changed Discussion --
&&
.SHORT TERM /6 AM MONDAY MORNING THROUGH MONDAY NIGHT/...
By early morning Monday, a weak area of showers may be in the
vicinity of the Lower Hudson Valley. These should remains confined
to the northwestern portion of the area before pushing north. A
generally dry day is expected with increasing cloud cover as onshore
flow continues to push moisture into the area. Highs on Monday are
expected to be slightly below average with temperatures peaking out
in the middle to upper 70s.
Though the upper level pattern is fairly zonal on Monday, a
deepening trough over the Great Lakes and Upper Midwest will aid
development of a weak surface trough over the East Coast by Monday
night. This may result in some weak forcing for ascent Monday night
into Tuesday morning. While models differ slightly in timing and
organization of any showers, CAMs seem fairly consistent in bringing
in showers late Monday into early Tuesday morning.
&&
.LONG TERM /TUESDAY THROUGH SUNDAY/...
Overall trend the last 24H is pointing toward a wetter solution
as an upper trough approaching from the Great Lakes interacts with
a frontal system backing up as a warm front Monday night into
Tuesday. Around the same time frame, Tropical Cyclone Franklin
is expected to lift north in the Western Atlantic and pass well
east of the area during the day Wednesday as the system is
progged to stay offshore with no direct impacts. However, some
indirect impacts will be dangerous rip currents due to an
increasing swell and high surf, especially out east with regard
to the surf.
With an onshore easterly flow it appears that instability will
be fairly minimal and much of the activity will be in the form
of showers, however, did mention isolated thunder Tuesday
night as the cold front associated with the upper trough
approaches. The latter of which will move through Wednesday
morning. Showers will be with us throughout the day Tuesday,
first with the aforementioned warm front backing in off the
Atlantic, then later with the upper trough and sfc cold front.
Have increased rainfall amounts from around half inch north and
west of NYC, to close to an inch across eastern Long Island and
southeast CT. There is still remains uncertainty as to how far
NW the rain shield pushes in from the Atlantic with the NAM12
the most aggressive of solutions with as much as 5 inches of
rainfall across the twin forks of LI. There is though good
overall agreement of half to one inch amounts across the area as
is currently forecast. As we get closer to the event, CAMs and
the placement of the boundary should improve giving us a better
idea of any heavy rainfall potential. However, at this time,
the threat remains low. In addition, the exit region of the
upper jet may allow for some of this rainfall expand farther
inland. This will have to be watched.
Cold front will pass through Wednesday morning with the threat
of showers ending from west to east in the afternoon. There have
been some signs of the upper tough slowing a bit and this may
delay the front and ending of the showers. The NAM is also
outlier here in a more closed off upper trough and bringing in
a frontal wave from the SW on Wednesday with additional
rainfall.
Behind the cold front. a much drier, cooler airmass will work in
for the end of the week. Temperatures rebound to normal next
weekend ahead of another frontal system. The latter of which
looks to move through next Sunday, but the magnitude of the
upper trough and cooler air to follow differ at this time.
Tropical cyclone Idalia is forecast to pass to our south and
off the Carolinas Thursday into Friday. The northern edge of the
cloud canopy from this system may lead to more clouds than sun
on Friday but all indications for now is it stays dry this far
north.
Monitor https:/www.weather.gov/okx/tropical or http/www.nhc.noaa.gov
for the latest NHC forecasts on this tropical system and others.
&&
.AVIATION /00Z MONDAY THROUGH FRIDAY/...
-- Changed Discussion --
High pressure remains to the north of the area tonight, and
moves off the New England coast Monday. A weak frontal boundary
and wave of low pressure approach from the south late in the
forecast period.
Sea breezes end early this evening, and winds become generally
light and variable, to light southeast along the coast. A light
east to southeast flow develops late tonight, and MVFR ceilings
will be developing or moving into the region from the east.
There is uncertainty with the timing of MVFR conditions and how
far west the ceilings will go before morning. With lower
confidence that MVFR reaches into the northeastern New Jersey
terminals only used a TEMPO at KEWR and KTEB. Conditions improve
back to VFR late morning west and into the afternoon east.
A few showers will be possible at KSWF in the morning, with
slight chance and no impact to VFR expected used a PROB30.
...NY Metro (KEWR/KLGA/KJFK/KTEB) TAF Uncertainty...
Uncertainty with the timing of developing MVFR ceilings late
tonight and toward Monday morning. Also, uncertain, and low
confidence, if the MVFR ceilings will reach KEWR and KTEB before
Monday morning. Amendments possible.
OUTLOOK FOR 00Z TUESDAY THROUGH FRIDAY...
Monday night: Becoming MVFR with a chance of showers late.
Tuesday: MVFR or lower in SHRA, especially late day and at night.
Wednesday: MVFR possible in the morning in shra, otherwise mainly
VFR.
Thursday and Friday: VFR.
Detailed information, including hourly TAF wind component forecasts,
can be found at: https:/www.weather.gov/zny/n90
Detailed information, including hourly TAF wind component forecasts,
can be found at: https:/www.weather.gov/zny/n90-- End Changed Discussion --
&&
.MARINE...
Sub-SCA conditions are expected through Tuesday as high
pressure builds in and then slides offshore.
An increasing SE / S swell into Tuesday night and through the day
Wed will lead to small craft conditions on the ocean as seas climb
to 5 to 6 ft for much of the ocean waters. Further east out on the
ocean 7 to 8 ft seas are more of a likelihood Wed and Wed night.
Also by Wed night, marginal small craft gusts to 25 kt in a
northerly flow are possible for the ocean waters. Also during
this time period, rather energetic S to SE swells will peak at
13 to 14 seconds. Seas are then expected to come down gradually
Thu into Fri with a long period SE swell lingering.
&&
.HYDROLOGY...
There are no hydrologic issues through next week at this time.
&&
.TIDES/COASTAL FLOODING...
-- Changed Discussion --
There is a moderate risk for rip current development for all the
beaches on Monday due to a 2-3 ft ESE swell and E winds
10-15kt, then becoming a high risk on Tuesday as more energetic
long period swells arrive from TC Franklin.
Swells from Tropical Cyclone Franklin begin to build late
Monday into Tuesday, then continuing and peaking into midweek
with 13 to 14 second long period swells for Wed and Wed night.
In addition, a full moon Wed night will have astro tides
increasing through the mid to late week period. Thus, chances
have increased for high surf and dangerous rip currents through
early Thursday. Combined with the high surf, the potential
exists for areas of ocean beach erosion/flooding and for
scattered areas of dune erosion during the times of high tide
Tue/Wed.
With respect to coastal flooding, minor coastal flood benchmarks
may be approached for some locations in the western south shore
bays of LI for the Mon night high tide cycle. More locations
like western LI Sound gauges in CT and perhaps Staten Island may
approach minor benchmarks Tue night, with some gauges in the
western LI south shore bays potentially exceeding minor
benchmarks for Tue night. This potential will likely linger into
the Wed night high tide cycle as well. In subsequent forecast
releases coastal flood statements, and coastal flood advisories
may be needed, especially for the western south shore bays.-- End Changed Discussion --
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
CT...None.
NY...None.
NJ...None.
MARINE...None.
&&
$$
SYNOPSIS...DW/MW
NEAR TERM...DW/MW
SHORT TERM...MW
LONG TERM...DW
AVIATION...MET
MARINE...DW/MW
HYDROLOGY...DW/MW
TIDES/COASTAL FLOODING...