000
FXUS61 KOKX 091813
AFDOKX
Area Forecast Discussion
National Weather Service New York NY
213 PM EDT Wed Aug 9 2023
.SYNOPSIS...
High pressure weakens and continues to build this afternoon.
Tonight, this high pressure area will shift offshore. A wave of
low pressure then approaches from the west on Thursday and moves
into the region Thursday night. The wave of low pressure is
expected to be east of the region by early Friday. High pressure
returns thereafter for the rest of Friday. High pressure
returns for Friday and lasts into at least part of Saturday
before another frontal system impacts us into early Sunday. High
pressure briefly settles in again before frontal system moves
in late Monday. High pressure returns for mid-week.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
Just some minor updates to the hourly forecast database with
this update. High pressure weakens and continues to build in
this afternoon. The pressure gradient therefore will gradually
weaken over the next several hours. With the high building and
pressure rising slightly, there will be more subsidence and
therefore less clouds and more sun for most areas for the next
couple of hours, followed by some scattered cumulus going
through later in the afternoon, especially further west. Also
some CAPE for far western portions of the CWA later this
afternoon and have PoPs up to 8-10 percent for far western areas
later this afternoon with low coverage convection off to the
west, but with very dry sub cloud layer and questionable low
level convergence zone have decided to not add any slight chance
PoPs in the forecast. A very warm day is expected even for
coastal areas with the breezy westerly winds mitigating marine
influence. Using consensus guidance for highs which are well
into the 80s. Dewpoints in the middle and upper 50s for most
locations make for a less humid day.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH FRIDAY/...
For tonight, the high pressure area will begin to move offshore. A
weakening of the pressure gradient is conveyed in the forecast
models with that low in the Canadian Maritimes moving farther away.
However, a wave of low pressure and upper level trough approaching
from the west will give extra high level cirrus clouds for late
night into Thursday morning. Light winds and mostly clear sky
conditions much of the night will lead to nearly optimal radiational
cooling. One other counteracting factor are surface winds becoming
more southerly, and this will be especially realized for the coastal
locations, so temperatures will not lower nearly as much over the
coastal locations. Using 3/4 CONSMOS and 1/4 NBM for lows which
range from the upper 50s to lower 70s.
For Thursday, the wave of low pressure approaches from the west
along with the upper level trough. Clouds lower and thicken in the
morning with chances of rain increasing during the day, becoming
likely in the afternoon into evening. Very little instability
present with this low pressure system in forecast models, only a
few hundred J/kg of surface CAPE, relatively highest across
coastal areas for the afternoon into evening. Thunderstorms will
be isolated much of the time, but could become scattered
briefly late afternoon into evening. GFS exhibits less
instability than NAM and NAM shows more elevated CAPE as
diagnosed from more negative Showalter Indices. Overall actually
GFS shows more positive lifted index than NAM which is more
negative. Bulk shear 0-6 km AGL comparing between NAM and GFS,
around 35-50 kt for NAM early Thursday evening with only around
30-35 kt for the GFS early Thursday evening. Some thunderstorms
could be strong, possibly severe especially across eastern
sections of the region towards Eastern Long Island and Southeast
CT. These locations will be closer to the maximum instability by
the forecast models, especially the NAM.
Used CONSAll/NBM for highs and lows. Smoothed out lows for
Thursday night to exhibit less spatial differences. Forecast
highs Thursday are mainly in the lower 80s and forecast lows
Thursday night are mainly in the 60s.
The forecast models depict the low east of the area by late
Thursday evening with rain showers continuing during the evening
and perhaps still ongoing into part of the overnight. Drying
conditions indicated late Thursday night when the low is even
farther east of the region with a breezy westerly flow resuming
with low pressure in the vicinity of Canadian Maritimes and high
pressure centered well south and west of the local region.
For Friday, high pressure returns building in from the west.
Dry conditions are expected. More sunshine expected and with
breezy westerly flow will not have as much marine influence.
Using CONSMOS and NBM for highs which are mainly in the low to
mid 80s with warmer end of the range along the coastal sections
of the region closer to the 84 to 86 degree range.
&&
.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
No real significant changes in the long term and stuck fairly close
to the NBM.
Long term starts off Friday night and early Saturday under high
pressure, so expecting mostly dry conditions. Saturday afternoon,
some mid level troughing develops out ahead of an approaching cold
front. Expecting just a slight chance of a shower or thunderstorm
mainly north and west of NYC. Those POPS increase a bit as we get
into Saturday night and the first part of Sunday as the front moves
across the region. Mainly drier conditions are expected for later
Sunday into the first half of Monday, however another frontal system
will bring unsettled conditions back to the region for Monday
afternoon into Tuesday. High pressure then returns for mid-week.
Temperatures will be near normal for this time of year through the
long term...generally in the 80s for highs.
&&
.AVIATION /18Z WEDNESDAY THROUGH MONDAY/...
-- Changed Discussion --
High pressure builds to the south and west today. Low pressure
approaches from the west late tonight into early Thursday
morning.
VFR through tonight. MVFR or lower conditions by very late in
the TAF period as low pressure affects the area.
A W to WNW flow will remain through the day. Gusts should
continue through the day, generally between 20-25kt, though they
may become more occasional this afternoon. Gusts diminish late
this afternoon or early evening.
Tonight, the flow becomes light and turns more southerly. Winds
increase a bit on Thursday morning, with some occasional gusts
possible by late morning. Winds may turn more SE later in the
morning. There is a great deal of uncertainty with wind
direction and speed due to uncertainty in strength and track of
the low pressure.
...NY Metro (KEWR/KLGA/KJFK/KTEB) TAF Uncertainty...
Gusts may diminish and end slightly earlier than forecast.
OUTLOOK FOR 18Z THURSDAY THROUGH SUNDAY...
Thursday: MVFR to IFR with Isolated thunderstorms possible. S to
SE wind gusts 15-20 kt. There is a great deal of uncertainty in
wind speed and direction due to uncertainty in strength and
track of low pressure.
Thursday Night-Friday: Showers end early Thursday night, then VFR. W
wind gusts 15-20 kt on Friday.
Saturday-Sunday: Mainly VFR. Chance of showers late Saturday
into Sunday.
Detailed information, including hourly TAF wind component forecasts,
can be found at: https:/www.weather.gov/zny/n90-- End Changed Discussion --
&&
.MARINE...
SCA ongoing for the eastern ocean, until 20Z this afternoon
east of Moriches as the small crafts were discontinued further
west across the ocean. Sub- SCA conditions elsewhere for non-
ocean marine zones with gusts near 20 kt until very late in the
day. Then after 20Z this afternoon, sub-SCA for all marine
zones through Thursday. Non- ocean zones stay below SCA Thursday
night and Friday with ocean getting back into SCA conditions
for that same time period.
Sub-SCA conditions are expected Friday night through the weekend.
Seas may approach 5 ft early next week as a frontal system
passes over the waters.
&&
.HYDROLOGY...
Dry conditions forecast through tonight.
Next rain shower event will be Thursday into Thursday night.
Most rainfall amounts are near a half inch with locally higher
amounts possible. With any intense thunderstorms, there could be
some minor flooding in poor drainage, low-lying and urban
areas. Otherwise, no other hydrologic impacts are expected as
the showers and thunderstorms should be relatively rapid moving.
No anticipated hydrologic impacts Friday through Tuesday.
&&
.TIDES/COASTAL FLOODING...
There is a high risk of rip currents forecast at the ocean
beaches today with a moderate risk of rip currents on Thursday
at the ocean beaches.
Risk for rip currents was increased to high for today with buoys
indicating higher waves and longer period swell. Also, expecting
more steepness to the waves with the winds more opposing the
incoming southerly swell.
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
CT...None.
NY...High Rip Current Risk until 9 PM EDT this evening for NYZ075-
080-081-178-179.
NJ...None.
MARINE...Small Craft Advisory until 4 PM EDT this afternoon for ANZ350.
&&
$$
SYNOPSIS...JM
NEAR TERM...JE/JM
SHORT TERM...JM
LONG TERM...BC
AVIATION...JP
MARINE...BC/JE/JM
HYDROLOGY...BC/JM
TIDES/COASTAL FLOODING...