965
FXUS61 KOKX 071957
AFDOKX

Area Forecast Discussion
National Weather Service New York NY
357 PM EDT Sun Jul 7 2024

.SYNOPSIS...
A weak frontal boundary or surface trough will remain in close
proximity to the area through Wednesday. A low pressure system
approaches for Thursday with an associated cold front. This
system and its cold front are expected to slow down and weaken
as they continue to approach through Thursday night. The frontal
boundary becomes nearly stationary within or near the region
going into the beginning of next weekend before moving east of
the region for the latter half of next weekend..

&&

.NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
Light winds with warm and humid air are expected to combine for
another night of low clouds and fog for much of the area east of NYC
tonight. Dewpoints are not expected to be as high as they were last
night, so the extent of any dense fog is uncertain. Not enough
confidence to go with a dense fog advisory at this point, but this
may eventually be needed for these areas east of the city. Dry, but
muggy conditions otherwise for the entire area tonight.

&&

.SHORT TERM /6 AM MONDAY MORNING THROUGH TUESDAY/...
The upper air pattern features a longwave trough centered over the
mid section of the country and a subtropical high over the western
Atlantic. The trough flattens into Tuesday as it shifts east. At the
surface, a stationary front, most likely east of the city, gets
pushed westward with the help of weak surface ridging to the east
and sea breezes. Mechanical forcing is weak, and with a mid-level
cap in place, anticipating a dry day for Monday. With the frontal
boundary moving west, SE CT and eastern LI should see more sunshine
in the afternoon than what`s occurred for the past few days.
Remaining dry for Monday night with low stratus development
probable for coastal areas. At least patchy fog is anticipated, but
turbulent mixing near the top of the boundary layer may be greater
this time around, so overall chances of dense fog right now appear
to be less.

For Tuesday, the stationary front most likely remains in the vicinity
of the western zones through the day. Better forcing from aloft with
a weaker mid-level cap plus greater instability with higher CAPE
values will bring the chance of mainly afternoon showers and
thunderstorms. Better overall chances will be north and west of the
city, closer to the frontal boundary, but can`t rule out development
along sea breezes as well. Moderate CAPE with a relatively weak
shear environment favors pulse severe if any severe weather
materializes, but overall chances of severe are low. The flow aloft
will promote slower moving cells, and given that PWATs increase on
Tuesday with a chance of some moisture feed in association with
Beryl, there is a low threat of flash flooding - again mainly north
and west of the city.

Regarding temperatures and heat indices for Monday and Tuesday,
temperatures at the top of the mixed layer are progged to be
similar, perhaps a little warmer for Tuesday, however Tuesday should
feature more cloud cover and higher dewpoints in general. Both days
feature S to SE winds for a good portion of the forecast area,
limiting surface dewpoint lowering during peak heating. Even where
winds would be more SW, moisture pooling along the stalled boundary
would work against dewpoints trying mixing out. NBM looked good for
high temperatures both days, however its dewpoints might be a little
too high through Tuesday morning. Used superblend for dewpoints
through Tues morning, then a blend of superblend and NBM for Tuesday
afternoon. A heat advisory will now be posted for most of the
forecast area for heat indices of 95 to around 100 both days.

&&

.LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/...
Main points before going into detail with regarding to forcing
mechanisms and synoptic features.

* Very warm and humid conditions forecast. The combination of most
  hot temperatures and most humid conditions are forecast on
  Wednesday with Thursday coming in second. This is taking into
  account the max heat indices forecast for Wednesday through next
  weekend. Max heat indices forecast in mid to upper 90s for much of
  the area Wednesday and to a lesser spatial extent for Thursday.
  So, potentially could very well see more heat advisories for
  Wednesday and possibly Thursday.

* Showers and thunderstorms are forecast but for the most part will
  remain isolated to scattered in coverage for much of the long
  term. Not expecting rain to occur the entire timeframe. However,
  thunderstorms could easily bring heavy rain. See hydrology section
  for further details.

* Potential for remnants of Beryl to increase precipitable waters
  with increased tropical moisture. This will make for a relatively
  greater potential for heavy downpours with any thunderstorms that
  occur.

From analysis of the LREF, the main synoptic pattern features a
strengthening building Western Atlantic ridge in mid levels with the
upper level jet staying along US and Canada border and into Canadian
Maritimes. Upper level jet winds increase for the latter half of
next weekend.

At the surface, a weakening stationary frontal boundary remains in
the vicinity of the local region Tuesday night into Wednesday.

Meanwhile, a low pressure system to the west will be developing and
approaching the region. An associated warm front looks to lift
farther north of the region Wednesday into early Thursday with the
parent low going near or through eastern part of the Great Lakes.

The low along with its associated cold front weaken thereafter
through Friday night. The front eventually gets near or within the
local region where it will probably become nearly stationary.

Another low pressure system farther north within Canada looks to
help push the weakening front farther east and out of the local
region for the latter half of next weekend. POPs for showers and
thunderstorms trend lower Saturday night into next Sunday.

On a technical note, NBM dewpoints seemed too high for Wednesday so
blended in other guidance to lower dewpoints. Also, the GFS seemed
too aggressive with convection. Thinking the convection will be more
timed with diurnal instability each day.

&&

.AVIATION /20Z SUNDAY THROUGH FRIDAY/...
A frontal system remains stalled nearby through Monday.

VFR for all terminals through late this afternoon. Guidance has
backed off on the fog and low stratus for tonight. Do expect IFR or
lower to move back into KGON tonight, and MVFR or lower for KISP and
KBDR. KJFK will see TEMPO MVFR conditions between 06-10Z. However,
there is a great deal of uncertainty with how far west the fog and
low stratus pushes, with some guidance bringing KJFK down to LIFR at
times. KLGA could also see MVFR or lower, but it is less likely here.

A S to SE wind at 5-10 kts this this afternoon becomes light
and variable tonight. Monday, winds will again be S to SE 5-10
kts.

 ...NY Metro (KEWR/KLGA/KJFK/KTEB) TAF Uncertainty...

Uncertainty regarding how far west fog/low stratus goes. KJFK
may see prevailing MVFR or lower conditions after 06Z while KLGA
has a lower potential for these conditions.


OUTLOOK FOR 18Z MONDAY THROUGH FRIDAY...

Monday: VFR.

Tuesday PM through Friday: Periods of MVFR OR IFR with
showers/thunderstorms.

Detailed information, including hourly TAF wind component forecasts,
can be found at: https:/www.weather.gov/zny/n90

&&

.MARINE...
Potential repeat of last night with dense fog for for Eastern LI
Sound, the ocean waters east of Fire Island Inlet, and the adjacent
bays through 2 pm. Some guidance suggests that this may push west of
Fire Island Inlet and get into parts of NY Harbor, as well as
western LI sound. Should a dense fog advisory be issued later
today/this evening, it will probably need to go through Monday
morning. Fog probably less widespread Monday night into Tuesday
along with a lower chance of it being dense. Confidence is not high
on this, but something that will need to be watched. With a
relatively weak pressure gradient in place, conditions on the waters
are otherwise expected to be below small craft advisory thresholds
through Tuesday.

For Tuesday night through Wednesday night, a weak pressure gradient
will allow for conditions to remain below SCA thresholds on all
waters.

For Thursday through Friday night, another low pressure system and
associated cold front approach but are expected to weaken. An
initial increase in the pressure gradient Thursday into early
Thursday night with weaken Friday through Friday night.

Possible SCA ocean seas Thursday with higher chances for SCA ocean
seas Thursday night through Friday night. Non-ocean waters stay
below SCA thresholds for seas and wave heights. For wind gusts,
possible SCA level wind gusts Thursday into Thursday night for ocean
waters and South Shore Bays.

So, SCA potential for ocean Thursday through Friday night. SCA
potential for South Shore Bays Thursday into Thursday night.
Otherwise, other waters are forecast to remain below SCA
thresholds.

&&

.HYDROLOGY...
There are no hydrologic concerns through Tuesday morning.
Thereafter, moisture increases along a stalled boundary nearby
Tuesday afternoon, and even more so later in the week with the
approach of another frontal boundary. This will bring a chance of
minor/poor drainage flooding as well as potential localized flash
flooding Tuesday afternoon/evening to the north and west of NYC.

Extended period with 2+ inch PWATS Tuesday night through Friday and
perhaps even through Friday night. Highest forecast PWATS Thursday
into Thursday night with potentially up to 2.5 inches. Any
thunderstorms Tuesday night through Friday will be capable of
producing heavy rain. There will be chances for minor flooding and
low probability, marginal risk, for localized flash flooding.


&&

.TIDES/COASTAL FLOODING...
A moderate rip current risk is forecast today at the ocean
beaches with southerly 5-10 kt winds and ocean waves of around
3-4 ft. For Monday, winds remain nearly the same as the previous
day but with ocean seas further subsiding to near 2 to 3 ft,
expect a low rip current risk.

&&

.OKX WATCHES/WARNINGS/ADVISORIES...
CT...Heat Advisory from noon Monday to 8 PM EDT Tuesday for
     CTZ005>010.
NY...Heat Advisory from noon Monday to 8 PM EDT Tuesday for
     NYZ067>075-078-176>178.
NJ...Heat Advisory from noon Monday to 8 PM EDT Tuesday for NJZ002-
     004-006-103>108.
MARINE...None.

&&

$$

SYNOPSIS...JC/JM
NEAR TERM...JC/DW
SHORT TERM...JC
LONG TERM...JM
AVIATION...JP
MARINE...JC/JM
HYDROLOGY...JC/JM
TIDES/COASTAL FLOODING...