580
FXUS61 KOKX 012032
AFDOKX
Area Forecast Discussion
National Weather Service New York NY
432 PM EDT Thu Aug 1 2024
.SYNOPSIS...
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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/...
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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, which has already started along a
warm front. 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.
Isolated showers have popped up to our west. They are tracking east,
but so far have been struggling to hold together as they enter the
CWA in the Lower Hudson Valley and NE NJ. For now, have kept only
isolated chances for a shower or thunderstorm through this evening
for NE NJ, Lower Hudson Valley and NYC metro. Should any of it hold
together, it will likely be low-impact and brief.-- End Changed Discussion --
&&
.SHORT TERM /6 AM FRIDAY MORNING THROUGH FRIDAY NIGHT/...
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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.-- End Changed Discussion --
&&
.LONG TERM /SATURDAY THROUGH THURSDAY/...
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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.-- End Changed Discussion --
&&
.AVIATION /20Z THURSDAY THROUGH TUESDAY/...
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Weak high pressure through tonight gives way to an approaching
frontal system on Friday.
Mainly VFR through the TAF period. An isolated shower is possible
this afternoon/early evening, from NYC metro on NW. A higher
probability of showers and thunderstorms exists Friday afternoon and
evening.
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... Timing of
wind shifts at KEWR and KTEB may be off by an hour.
An occasional gust 15-20 kt possible at KEWR until winds shift to
the S-SE.
An isolated shower cannot be completely ruled out late this
afternoon or evening.
OUTLOOK FOR 18Z FRIDAY THROUGH TUESDAY...
Friday Afternoon-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...
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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.-- End Changed Discussion --
&&
.HYDROLOGY...
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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.-- End Changed Discussion --
&&
.TIDES/COASTAL FLOODING...
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A moderate risk of rip currents at ocean beaches continues into
Friday, due to a residual 3-ft swell.-- End Changed Discussion --
&&
.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
SHORT TERM...BR
LONG TERM...DW
AVIATION...DS
MARINE...BR/DW
HYDROLOGY...BR/DW
TIDES/COASTAL FLOODING...//