362
FXUS61 KOKX 171959
AFDOKX

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

.SYNOPSIS...
A weak low tracks slowly eastward through the Great Lakes region
tonight, and approaches Sunday. Meanwhile another low develops
during Sunday over southeastern Pennsylvania and eastern
Maryland. This low then deepens Sunday night into Monday and
tracks northeast bringing a cold front across the area late
Sunday night into Monday. A secondary frontal passage moves
through Tuesday. High pressure builds in for the middle and end
of the week.

&&

.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
With the potential for one round of moderate to heavy rainfall
late tonight into early Sunday morning have issued a Flood Watch
that begins at 06Z Sunday, for northeastern New Jersey into the
Lower Hudson Valley west of the Hudson River. The watch
continues through Sunday and into late Sunday night. Rainfall
rates late tonight may be near 1 inch per hour. Isolated flash
flooding is also possible a little farther to the east, into
New York City and Putnam and Westchester counties, with poor
drainage and urban flooding possible.

With the upper ridge remaining into the western Atlantic,
rainfall will be slow to move eastward tonight, and some eastern
sections may remain dry until late tonight or toward Sunday
morning.

&&

.SHORT TERM /6 AM SUNDAY MORNING THROUGH MONDAY/...
A Flood Watch is in effect from late tonight, 06Z Sunday,
through late Sunday night, 06Z Monday, for the potential for
scattered flash flooding, urban and poor drainage flooding, and
possibly fast responding streams of northeastern New Jersey.
Rainfall rates could be near 1 inch per hour, and at times
approach 2 inches per hour. Total rainfall in the watch area
will be around 2 inches to 2.5 inches with locally as much as 3
inches possible. This will be with a slow moving frontal system
and with training showers and isolated thunderstorms, as the
flow nearly parallels the trough. Also, precipitable waters
increase to just over two inches Sunday, and warm cloud process
increase along with a 20-230kt low level jet during Sunday and
into Sunday night. This system will be slow moving eastward as
downstream riding remains across the western North Atlantic. An
then during Sunday a frontal wave develops near the mid Atlantic
coast, across southeastern Pennsylvania into the Delmarva. This
low provides lift for heavy rainfall as this low tracks slowly
northeast to east across northeastern New Jersey into New York
City and then to the northeast of the area during Monday.

&&

.LONG TERM /MONDAY NIGHT THROUGH SATURDAY/...
The area remains under a large-scale trough with vorticity maxima
moving through Monday night and into Tuesday. As the trough tries to
lift during the day on Tuesday, additional energy descends from the
north to allow for another round of forcing. At the surface, this
should translate into the form of a secondary frontal passage that
brings another round of showers with possible embedded
thunderstorms, especially Monday night into Tuesday morning. Any
residual showers should diminish into the afternoon on Tuesday with
the passage of the surface cold front.

There is still some uncertainty as to how quickly the trough lifts
with the upper-level energy rotating over New England, but consensus
has been that the trough departs late Wednesday into Thursday and
ridging begins to move over the area from the west. At the surface,
a relatively strong high pressure system builds into the Mid-
Atlantic and Northeast from Wednesday through the weekend. This will
provide fairly calm and dry conditions through the rest of next week.

This high pressure will be accompanied with primarily N/NW winds and
a much cooler airmass. The airmass should be fairly anomalously cool
for middle to late August. High temperatures on Tuesday and
Wednesday may not rise out of the upper 60s to low 70s for much of
the area. Even coastal areas, highs will only be in the low to maybe
middle 70s. Lows Wednesday night and Thursday night will likely be
fairly chilly, with some locations for the interior and outlying
areas possibly dropping into the low 50s or upper 40s, depending on
the strength of any radiational cooling. Temperatures will gradually
moderate into late week and the weekend with highs by Friday and
Saturday rising back into the upper 70s to low 80s.

&&

.AVIATION /20Z 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.
KGON could have some showers towards the end of the TAF period
during the day Sunday.

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, mainly for NYC terminals.

 ...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, and was extended through Monday night.

Elevated wave heights on the ocean zones will allow for SCA
conditions to continue Monday night and possibly into the day on
Tuesday with some marginal wind gusts near 20-25kt with the passage
of a cold front. Late Tuesday, wind diminish and wave heights should
fall below 5 feet. Sub-SCA conditions are then expected with high
pressure moving into the area by mid-week.

&&

.HYDROLOGY...
A Flood Watch is in effect late tonight into late Sunday night
for Northeastern New Jersey and into the Lower Hudson Valley
west of the Hudson River.

Locally heavy rainfall is possible late tonight, and again
during Sunday into Sunday night, particularly west of the NYC
metro and Hudson River. The threat of heavy rainfall expands to
the east into Western Long Island and portions of southern, and
with the slow movement of low pressure and lower rainfall
amounts and rainfall rate was not confident enough to go
farther to the east with the Flood Watch.

Total rainfall amounts from tonight through Monday night range
from around a half inch east to around 2 inches from NYC metro
on north and west. Locally higher amounts, possibly up to 3
inches, are possible across northeastern New Jersey into the
Lower Hudson Valley. Isolated to scattered instances of flash
flooding are 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 hydrologic concerns Tuesday through next weekend.

&&

.TIDES/COASTAL FLOODING...
A high rip current risk is in place through Monday. This is due
to SE to S long period swells from Hurricane Ernesto.

Ocean seas are forecast to be highest Sunday into Monday, with
heights up to 6-7 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...Flood Watch from 2 AM EDT Sunday through late Sunday night for
     NYZ067-069.
     High Risk for Rip Currents through Sunday evening for NYZ075-080-
     081-178-179.
NJ...Flood Watch from 2 AM EDT Sunday through late Sunday night for
     NJZ002-004-006-103>108.
MARINE...Small Craft Advisory until 6 AM EDT Tuesday for ANZ350-353-355.

&&

$$

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