571
FXUS61 KOKX 171814
AFDOKX

Area Forecast Discussion
National Weather Service New York NY
214 PM EDT Sat Aug 17 2024

.SYNOPSIS...
High pressure remains centered offshore today as a weak low
tracks through the Great Lakes. The low approaches on Sunday,
with an associated warm front lifting through into Sunday night.
A cold front then follows Monday, with a secondary frontal
passage into Tuesday. High pressure then builds through the end
of the week.

&&

.NEAR TERM /THROUGH TONIGHT/...
With numerous showers moving through northeastern New Jersey into
the Lower Hudson Valley and portions of New York City, did an update
for probabilities to increase to categorical for the remainder of
the afternoon. Otherwise, forecast on track.

Upper ridging in place locally shifts to the east as surface high
pressure remains centered offshore today. Digging trough over the
Great Lakes begins to approach, and a frontal system on the leading
edge will begin to approach. The upper ridge to the east will keep
the eastern sections dry through late this afternoon as showers
dissipate.

The shower activity expands in coverage this evening and tonight
with passing shortwave energy, but still appears mostly confined to
the western half of the region. Some varying solutions from the 00Z
CAMs, with the NAM 3km much less enthused with rainfall tonight, and
the HRRR much more bullish and farther east with the placement. For
now, opted for lower likely PoPs (60%) given the disagreement, with
this mainly extending over NE NJ and the Lower Hudson Valley and
decreasing to the east. Not entirely out of question a few embedded
thunderstorms develop tonight as well, though this remain rather
limited.

&&

.SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
Unsettled start to the week as the upper trough and frontal system
track through the Northeast and bring several periods of rainfall.

Scattered showers around Sunday morning should lessen in coverage
by lunchtime, and much of the afternoon could remain dry, especially
east. Into the evening, rain chances increase once again as a
frontal boundary begins to approach. Limited shear and instability
should keep activity mainly sub-severe and disorganized, but can`t
rule out thunderstorms. Of greater concern is the potential for
training convection and heavy downpours given a persistent moisture
feed from the south increasing PWATs to near 1.75" during this time,
raising the risk of heavy downpours that could lead to flooding.
This threat appears highest from NYC on north and west, and lines
up with where WPC currently has a slight risk for excessive rainfall
on Sunday. Though still some uncertainty with the placement of the
axis of heaviest rainfall, which will be critical in fleshing out
the nature and location of the threat.

A cold front follows Monday into Monday night with the potential
of a weak wave forming along the boundary as it moves through
the region, instigating another round of showers and thunderstorms.
There remains the potential for locally heavy rainfall, as well
as an isolated flash flood threat with this activity. Rain chances
finally start to lower Monday night into early Tuesday as the
complex progresses east and a much drier regime begins to take
hold. Total QPF through this period averages around a half inch
across eastern areas, to between 1 and 2 inches from NYC and
points north and west.

&&

.LONG TERM /TUESDAY THROUGH SATURDAY/...
It appears that a cold front will be over us or just shifted through
during Tuesday morning. High pressure will have a tough time
building behind its passage during the rest of Tuesday as an upper
trough axis remains over us. Chance of showers at any point of the
day, but overall it should be dry most of the time. Can`t completely
rule out a thunderstorm in the afternoon due to the cold pool aloft,
but will leave it out of the forecast for now. The trough axis
shifts east during Wednesday, and with limited moisture, it should
be a dry day. The flow aloft flattens for Thursday and Friday with a
continuation of dry weather as surface high pressure builds in.
Highs only in the 70s for Tuesday through Thursday, then around 80
on Friday.

&&

.AVIATION /18Z SATURDAY THROUGH THURSDAY/...
A frontal system approaches the terminals through the TAF
period.

Mainly MVFR conditions are expected through the TAF period.
Intermittent showers expected across all terminals except for
KGON. KGON expected to remain mostly dry during the TAF period.

There could be an isolated embedded thunderstorm as well
tonight into Sunday. Chances for thunderstorms increase Sunday
afternoon. At this time, too much uncertainty for thunderstorm
timing and locations to put in any TAFs.

Regarding winds, overall expecting SE winds near 10 kt much of
the TAF period. Some occasional gusts 15-20 kt will be possible
this afternoon as well as Sunday afternoon.

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

There could very well be some fluctuation in category during
the TAF period. Categories could fluctuate between MVFR and VFR
this afternoon into this evening. IFR will be possible at times
Sunday.

OUTLOOK FOR 18Z SUNDAY THROUGH THURSDAY...

Sunday afternoon-Sunday night: Showers moving in from the west.
A chance of thunderstorms. MVFR to occasional IFR conditions.

Monday: Showers with a chance of thunderstorms. MVFR or lower at
times.

Tuesday: A chance of showers with MVFR possible. NW wind gusts 15-20
kt.

Wednesday-Thursday: VFR.

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

&&

.MARINE...
Rough ocean seas and long period swells, 12 to 15 second, will
persist this weekend and into early next week as distant TC
Ernesto passes well offshore in the open Atlantic. This will
also lead to rough conditions around inlets. Please refer to the
National Hurricane Center for official forecasts regarding
Hurricane Ernesto.

A Small Craft Advisory is in effect for the ocean zones through
Sunday night for elevated swells increasing toward 7 ft. This
will likely need an extension through at least Monday with lingering
seas.

Swells and seas should diminish Tuesday into Wednesday with seas
below 5 ft sometime on Tuesday. Otherwise, below SCA conditions are
expected Sunday through the middle of the week.

&&

.HYDROLOGY...
Locally heavy rainfall is possible Sunday into Sunday night,
particularly west of the NYC metro and Hudson River. This
threat expands to much of the area Monday into Monday night.
Total rainfall amounts range from around a half inch east to 1
to 2 inches from NYC metro on north and west. Locally higher
amounts are possible. Isolated to scattered instances of flash
flooding is possible across the more flood prone areas of NE NJ
and adjacent areas of the Lower Hudson Valley, and perhaps as
far east as NYC. A more widespread threat for localized flash
flooding, along with nuisance flooding of urban and poor
drainage areas, sets up on Monday.

No additional hydrological concerns follow Tuesday through late next
week.

&&

.TIDES/COASTAL FLOODING...
A high rip current risk is in place through Sunday. This is due to
SE to S long period swells from Hurricane Ernesto. The high risk
will likely need to be extended into at least Monday.

Ocean seas are forecast to be highest Sunday into Monday, with
heights up to 7 ft. There is potential for high surf along the
ocean beaches during this time frame as well as beach erosion.

Minor coastal flooding is expected this evening along the back bays
of Nassau, where a statement has been issued. Advisories will likely
be needed for subsequent high tide cycles for the back bays of
Nassau and Queens, the lower NY Harbor, and the SW CT coastline,
where water levels may touch minor thresholds through much of this
upcoming week per elevated astronomical high tides due to the full
moon on the 19th and swell from Hurricane Ernesto.

Please refer to NHC for official forecasts regarding Hurricane
Ernesto.

&&

.OKX WATCHES/WARNINGS/ADVISORIES...
CT...None.
NY...High Risk for Rip Currents through Sunday evening for NYZ075-080-
     081-178-179.
NJ...None.
MARINE...Small Craft Advisory until 6 AM EDT Monday for ANZ350-353-355.

&&

$$

SYNOPSIS...JC/DR
NEAR TERM...DR/MET
SHORT TERM...DR
LONG TERM...JC
AVIATION...JM
MARINE...JC/DR/MET
HYDROLOGY...JC/DR
TIDES/COASTAL FLOODING...BG