218
FXUS61 KOKX 080114
AFDOKX

Area Forecast Discussion
National Weather Service New York NY
914 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/...
Forecast remains on track into the overnight.

Another night of light winds and warm and humid air, especially
east of the NYC. Low clouds should develop and expand with some
fog, especially along the immediate shore. Dewpoints are not
expected to be as high as they were last night, so the extent of
any dense fog is uncertain. Still not enough confidence to go
with a dense fog advisory at this point, but this may eventually
be needed for some 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 SATURDAY/...
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 /01Z MONDAY THROUGH FRIDAY/...
A frontal system remains stalled nearby through Monday.

VFR for most terminals through Monday. The only exceptions will
be at KGON an potentially KISP and KBDR. IFR is expected to
develop tonight and could drop to as low as LIFR, especially at
KGON. Think the low clouds and low visibilities stay east of
KJFK with VFR prevailing there.

Light SE winds will become light and/or variable tonight. A light
NE flow may develop after 12z Monday before shifting to the
S-SE 5-10 kt late morning into the afternoon.

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

Low chance for IFR conditions at KJFK around 08-12z.

Timing of S-SE winds Monday may be off by 1-2 hours.

OUTLOOK FOR 00Z TUESDAY THROUGH FRIDAY...

Monday Night-Tuesday morning: VFR.

Tuesday afternoon through Friday: MVFR or IFR possible at times
with periods of showers/thunderstorms.

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

&&

.MARINE...
Have expanded the marine dense fog advisory to include the
eastern Long Island Sound. No other changes were made, but there
is a possibility for further expansion of the advisory if
confidence increases it will expand further westward overnight.

The dense fog may linger beyond that time into Monday
afternoon, but did not have enough confidence to extend the
advisory later than 12pm.

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...
There is a low rip current risk on Monday with light winds and
seas 2 to 3 ft. There is a moderate rip current risk on Tuesday
as southerly winds increase and seas may build a bit compared to
Monday.

&&

.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...Dense Fog Advisory until noon EDT Monday for ANZ332-350-353.

&&

$$

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