000
FXUS61 KOKX 100000
AFDOKX
Area Forecast Discussion
National Weather Service New York NY
800 PM EDT Sat Sep 9 2023
.SYNOPSIS...
A frontal boundary will remain over or in close proximity to the
area for the remainder of the weekend, passing to the east late
Monday. Another cold front passes through the area on Wednesday,
followed by high pressure building in for the second half of
the week.
&&
.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
Severe Thunderstorm Watch that was in effect for portions of the
area has been cancelled. Much of the showers and thunderstorms
have lifted north of the Lower Hudson Valley and will do so
shortly across interior southern CT. Severe weather is unlikely
for the rest of tonight.
An upper trough will remain nearly stationary tonight with
a stalled frontal boundary along its leading edge draped across
the forecast area. The front has resided generally from just NW
of NYC, across the Lower Hudson Valley, and into western CT.
The area resides under a moderate to high CAPE, weak shear
environment, with PW values around 1.75" (90th percentile SPC
climo). So while organized severe convection is unlikely, there
is the potential for localized heavy rainfall.
The remainder of the evening should be fairly quiet outside of
some widely scattered showers and thunderstorms. The question
remains does any of the upstream activity across the Mid
Atlantic initiate an MCV that reignites showers and thunderstorms
late tonight. The CAMs have generally backed off on this idea,
however, some of the larger scale models (convective
parameterization) indicate this as a possibility.
As for temperatures, this will be another unseasonably warm,
humid night with cloud cover, and patchy fog. Lows will range
form the upper 60s inland, to the lower 70s at the coast. This
is about 10 degrees above normal.
&&
.SHORT TERM /6 AM SUNDAY MORNING THROUGH SUNDAY NIGHT/...
Not much change on Sunday with the stationary front remaining
across the area. Heights aloft do begin to fall slightly as
another upper trough digs across central Canada and the Great
Lakes, nudging the upper trough over the Ohio and Tennessee
Valleys eastward. This may also allow the boundary to shift
slightly eastward on Sunday along with the chances of showers
and thunderstorms. The environment looks a bit more stable on
Sunday, but still moisture-laden with a slow storm motion.
Should we be able to achieve more sun, another high CAPE, low
shear environment would support pulse severe. There is a bit
stronger vertical wind profile on Sunday.
WPC has placed the area under a Slight Risk for Excessive
Rainfall on Sunday across NE NJ, the Lower Hudson Valley, and
SW CT. This will depend on the placement of the front as it
could deviate some from where it was on Saturday.
The 12Z NSSL WRF (SPC HREF) closely mirrors what we have seen
the last couple of days with late afternoon/evening convection
developing along the boundary and then lifting north. However,
it looks to be a bit farther east.
What`s left of the upper trough shears off to the NE Sunday
night into Monday with a diffuse frontal boundary working east.
This will continue the chance of showers and thunderstorms on
Sunday night. Granted it will not be raining all the time, but
the potential is there.
Conditions will remain humid with highs Sunday closer to normal
due to the forecast of convection and cloud cover. However,
should more sun be realized, temperatures could get higher than
currently forecast. Most locations are forecast to be in the
upper 70s to lower 80s. Lows Sunday night will change little,
ranging from the upper 60s to lower 70s.
&&
.LONG TERM /MONDAY THROUGH SATURDAY/...
-- Changed Discussion --
The global ensembles are in general agreement with the basic
evolution of the synoptic pattern for the long term. As a
shortwave trough moves offshore by Monday morning, heights begin
to rise a bit as some weak ridging builds in aloft under
southwest flow.
The stationary boundary remains in and around the area during
the day Monday keeping clouds and shower/thunder chances in
+through the day. Model profiles do indicate some instability so
have maintained the thunder chances as well until Monday
evening.
By late Monday into Tuesday, a positively tilted upper trough
begins to enter the picture dropping into the Lower 48 over the
Great Lakes. This energy pushes the aforementioned stationary
front offshore by late Monday. Surface low pressure associated
with this upper low allows a warm front to approach the area by
late in the day Tuesday. So while Tuesday looks to remain mostly
dry at this point, clouds will be on the increase with
increasing shower chances by Tuesday night.
The cold front then approaches on Wednesday, providing additional
precipitation chances. While the better upper forcing resides north
of the area, and with PWATS around 1-1.5", there is a 15-20% chance
of >1" in 6 hours per latest NBM, especially north and west of NYC.
The front heads offshore by late Wednesday, with high pressure then
building in on Thursday and Friday ushering a cooler and drier
airmass.
The humidity will continue though Wednesday, with dewpoints
continuing into the upper 60s and low 70s. High temperatures
however will remain in the upper 70s and lower 80s through the
period given the cloud cover and precipitation. Lower humidity
air works in Wednesday night behind the cold front passage.
Long period swells will begin to build late Wednesday through
Friday from distant tropical cyclone Lee that may result in high
surf conditions and dangerous rip currents across the Atlantic
facing beaches. Monitor https:/www.weather.gov/okx/tropical or
http/www.nhc.noaa.gov for the latest NHC forecasts on Hurricane
Lee and others.-- End Changed Discussion --
&&
.AVIATION /00Z SUNDAY THROUGH THURSDAY/...
-- Changed Discussion --
A stationary front remains over the area through the weekend
while high pressure remains offshore.
MVFR to IFR ceilings develop once again this evening and
overnight, with the coastal terminals lowering first. There are
uncertainties with the timing of development of stratus, and
where and when any fog will occur overnight. There is a chance
of LIFR at KGON toward Sunday morning. Conditions then improve
back to VFR during the morning. With the stationary front
remaining in the vicinity showers and thunderstorms are expected
to develop once again late Sunday morning into the afternoon,
and a few stronger storms will produce heavy rainfall.
Winds remain light, but directions will vary depending on the
terminals location relative to the stationary front. A S-SE flow
should largely be 10 kt or less through Sunday.
NY Metro (KEWR/KLGA/KJFK/KTEB) TAF Uncertainty...
Amendments for timing of lowering conditions and flight
categories, and then for improvement to VFR Sunday morning.
OUTLOOK FOR 00Z MONDAY THROUGH THURSDAY...
Sunday night-Monday: Showers with a few thunderstorms possible
mainly each afternoon and evening. MVFR or lower conditions
possible in stratus and fog , especially at night and early
morning.
Tuesday: Mainly VFR. Chance of showers.
Wednesday: Showers likely with MVFR to IFR possible.
Thursday: VFR.
Detailed information, including hourly TAF wind component forecasts,
can be found at: https:/www.weather.gov/zny/n90-- End Changed Discussion --
&&
.MARINE...
With a weak pressure gradient in place, winds and seas will remain
below SCA thresholds through early next week.
Confidence is increasing that swells from distant Hurricane Lee
build by midweek, with SCA seas likely developing on the ocean
by Wednesday. Ocean seas may reach 10 to 15 ft by late Friday
resulting in high surf and dangerous rip current conditions.
Monitor https:/www.weather.gov/okx/tropical or http/www.nhc.noaa.gov
for the latest NHC forecasts on Hurricane Lee and others.
&&
.HYDROLOGY...
Showers and thunderstorms through the weekend will be capable
of heavy downpours and localized to scattered flash flooding.
The best chance looks to Sunday, primarily across NYC, NE NJ,
the Lower Hudson Valley, and SW CT. The latter of which will
depend on where the stationary front sets up. Rainfall rates of
1 to possibly 2 inches an hour can be expected with any slow
moving strong thunderstorms.
Slow moving showers and thunderstorms may result in minor/nuisance
flooding on Wednesday afternoon. Otherwise, no widespread hydrologic
impacts are expected Monday through Friday.
&&
.TIDES/COASTAL FLOODING...
The rip current risk for Sunday will be low. However, the rip current
risk will increase to moderate on Monday, and may become high
towards the late afternoon and early evening as energetic SE swells
begin to arrive from distant Tropical Cyclone Lee.
High surf as well as dangerous rips are possible along the oceanfront
through the remainder of the week.
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
CT...None.
NY...None.
NJ...None.
MARINE...None.
&&
$$
SYNOPSIS...DBR/DW
NEAR TERM...DW
SHORT TERM...DW
LONG TERM...DBR
AVIATION...MET
MARINE...DBR/DW
HYDROLOGY...DBR/DW
TIDES/COASTAL FLOODING...