231
FXUS61 KOKX 012349
AFDOKX
Area Forecast Discussion
National Weather Service New York NY
749 PM EDT Thu Aug 1 2024
.SYNOPSIS...
-- Changed Discussion --
Weak high pressure on Friday gives way to an approaching cold
front or trough that works slowly east across the area this
weekend. Weak high pressure will then briefly follow for Monday
before another cold front passes through the area Monday night.
The latter of which becomes stationary in close proximity to the
area through midweek.-- End Changed Discussion --
&&
.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
-- Changed Discussion --
Updates includes some small adjustments based on latest
obs/trends. Expect dry conditions through the night.
A trough exits to the east this evening, giving way to weak mid-
level ridging overnight and early Friday morning. This will also
lead to a returning south flow as a weak warm front approaches
from the south. This leads to increasing dewpoints overnight
with overnight lows in the mid-70s along the coast and lower-70s
along interior sections. Cloud cover starts to increase near
daybreak.-- End Changed Discussion --
&&
.SHORT TERM /6 AM FRIDAY MORNING THROUGH FRIDAY NIGHT/...
A shortwave trough deepens and approaches to our west on Friday.
This will lead to increasing dewpoints from southerly flow after the
passage of a warm front and increasing cloud cover Friday morning
and early afternoon.
Friday afternoon, scattered showers and thunderstorms are expected
to develop west and north of NYC. With ample shear and instability
available, some of the storms could be strong to severe, with the
primary threat from gusty winds. SPC has western portions of our CWA
under a Marginal Risk for severe weather. Later Friday evening,
pockets of mid-level energy pass over along with PWATs increasing
above 2 inches. This could lead to a developing line of showers and
thunderstorms that advances east late Friday evening into Friday
night. While instability will decrease late Friday evening,
decreasing the risk for severe weather, high PWATs could still lead
to some moderate to heavy downpours. The main risk for this will be
isolated and primarily north and west of NYC. Most 12Z CAMs show the
line of rain gradually weakening as it passes east over the CWA into
Friday night.
A Heat Advisory remains in effect for most of the CWA on Friday.
High temperatures will be in the low-90s to upper-80s with higher
afternoon dewpoints in the mid/low-70s on Friday compared to the
lower dewpoints that were seen Thursday. This will lead to another
day of mid/upper-90 heat index values. Cloud cover, which may
increase early on in western portions of the CWA may give early
relief to this heat before showers and thunderstorms start to
develop.
&&
.LONG TERM /SATURDAY THROUGH THURSDAY/...
An upper trough nearly cutoff from the westerlies across the
Ohio Valley into western portions of PA and NY on Saturday will
work slowly east through the weekend. This will result in a
good chance of showers and thunderstorms across the area,
especially during the afternoon and early evening hours due to
the time of greatest instability. Saturday though could be dry
for a good portion of the day due to weak shortwave ridging
aloft and the surface trough or weak cold front still west of
the area. This is not to say there can`t be widely scattered
activity, especially north and west NYC due to differential
heating across the higher elevations. Seabreeze activity seems
less likely Saturday, but should increase on Sunday due to a
lowering LCL and LFC. The trough/front washes out across the
area Sunday night and weak high pressure briefly builds in for
Monday ahead of a cold front approaching from the NW. The
airmass looks to be drier and more stable, thus chances of
convection along the front late in the day and at night are low.
Heading into midweek there is a bit more uncertainty with the
potential for a tropical system near the Southeast coast. It is
too early to specify the interaction with the frontal boundary
close the area for the midweek period. There will be low chances
for convection at this time. Operational globals are in decent
agreement through about 120h. That being said, the associated
tropical disturbance is being monitored by the NHC for
development over the Greater Antilles. Please refer to the
latest NHC products for the monitoring of this system.
As for temperatures, it will remain several degrees above normal
through Monday. Saturday will be close to heat indices around
95, especially for the NYC/NJ metro area. Confidence is not
high enough at this time to extend the heat advisory. Monitor
subsequent forecasts for the possible issuance. Cloud cover on
Sunday is expected to limit heating enough to keep heat indices
below criteria, but ahead of an approaching cold front on Monday
highs will rebound back into the upper 80s and lower 90s. Heat
indices on Monday are expected to be in the lower 90s due to a
slightly drier SW flow.
&&
.AVIATION /00Z FRIDAY THROUGH TUESDAY/...
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Weak high pressure through tonight gives way to an approaching
frontal system on Friday.
VFR. There is a chance of MVFR with showers and thunderstorms
late Friday into the evening, more likely north and west. A
stronger thunderstorm is possible with gusty winds.
Sea breezes weaken early, and winds become light and variable.
Southerly winds develop early Friday morning, and increase to
10-15kt during the afternoon. Occasional gusts up to 20 kt are
possible during the afternoon.
Winds will continue becoming S this afternoon. It may remain W
at KHPN and KSWF through the afternoon. Winds will diminish
again tonight, becoming light and variable. S-SE winds increase
again on Friday morning.
NY Metro (KEWR/KLGA/KJFK/KTEB) TAF Uncertainty...
There may be a few showers and thunderstorms early Friday
afternoon, then a chance of thunderstorms late in the day, with
timing uncertain. A stronger thunderstorm with gusty winds is
possible.
Southerly winds may become occasionally gusty at KEWR, KLGA, and
KTEB, up to 20kt.
OUTLOOK FOR 00Z SATURDAY THROUGH TUESDAY...
Friday night: Chance of MVFR/IFR showers and thunderstorms,
especially early. Then a chance of IFR in stratus and fog.
Saturday-Sunday: Chance of MVFR or lower in afternoon/evening
showers/thunderstorms.
Monday: VFR.
Tuesday: Mainly VFR. Low chance of showers and thunderstorms.
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 expected through Friday night.
Increasing/persistent S-SW flow will produce marginal SCA
conditions on the ocean waters late Saturday into Sunday. Sea
will gradually diminish Monday in a weakening flow and a
diminishing southerly swell.
Swells from a potential tropical system off the Southeast coast
could impact the ocean waters later next week. Please refer to
the latest NHC products for the monitoring of this system.
&&
.HYDROLOGY...
A round of showers and thunderstorms Friday afternoon into Friday
night could lead to some locally heavy downpours, mainly north and
west of NYC. WPC has a marginal risk for excessive rainfall for
areas north and west of NYC. Localized urban and poor drainage
flood impacts are a possibility with PWATs exceeding 2 inches
in spots.
WPC has a marginal risk for excessive rainfall slowly expanding
east through the weekend as slow moving upper trough and
weak surface cold front or trough works across the area.
&&
.TIDES/COASTAL FLOODING...
A moderate risk of rip currents at ocean beaches continues into
Friday, due to a residual 3-ft swell.
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
CT...Heat Advisory until 8 PM EDT Friday for CTZ005>010.
NY...Heat Advisory until 8 PM EDT Friday for NYZ069>075-078-176>179.
NJ...Heat Advisory until 8 PM EDT Friday for NJZ002-004-006-103>108.
Air Quality Alert until 11 PM EDT this evening for NJZ004-006-
103>108.
MARINE...None.
&&
$$
SYNOPSIS...BR/DW
NEAR TERM...BR/DW
SHORT TERM...BR
LONG TERM...DW
AVIATION...DS
MARINE...BR/DW
HYDROLOGY...BR/DW
TIDES/COASTAL FLOODING...