915
FXUS61 KOKX 180515
AFDOKX

Area Forecast Discussion
National Weather Service New York NY
115 AM EDT Wed Sep 18 2024

.SYNOPSIS...
High pressure moves offshore as a weak coastal low pressure
approaches the area from the south into the middle of the week.
Low pressure will linger just south of Long Island Thursday into
Friday before pushing further south on Saturday. High pressure
builds in from the northeast Sunday into early next week.

&&

.NEAR TERM /UNTIL 6 AM THIS MORNING/...
Forecast on track with updates for current conditions. Stratus
was beginning to develop/move into southeastern Connecticut and
portions of the Twin Forks.

Surface high pressure to the northeast will continue to remain
in place tonight with a light E to NE flow advecting moisture
onshore. Upper level ridging over the Northeast will continue to
erode as an upper level trough over the Southeast approaches
the area. At the surface, a low pressure will gradually move up
the coast increasing the E/NE flow late tonight and into
Wednesday.

Skies will become gradually cloudier tonight with possible low
stratus and patchy fog development late, especially in any areas
that can radiationally cool earlier in the night before the
denser cirrus shield overtakes the area. Lows tonight will be
in the middle 50s for the interior to low to middle 60s for the
coast.

&&

.SHORT TERM /6 AM THIS MORNING THROUGH 6 PM THURSDAY/...
The weak coastal low pressure system will be just to the south of
the area, off the Mid-Atlantic coast, by midday Wednesday. In
addition to increasing the northeasterly flow, moisture on the
northern fringe of the system will begin to approach the area. There
remains some uncertainty as to how expansive any rainfall may be but
at a minimum scattered showers can be expected as early as mid-
morning Wednesday, especially for the immediate coastal areas.

The low pressure system appears to spin just to the southeast of the
area off the coast through at least Thursday. This will result in a
chance of showers for much of the area, but primarily Long Island,
through this timeframe. While any precipitation is expected to be
fairly light and intermittent, some heavier rounds of rain are not
completely ruled out, especially for eastern Long Island where the
proximity to the low pressure may enhance precipitation rates for a
time Wednesday evening into Thursday morning.

Generally, 0.5 to 0.75" of rainfall is expected for the coast with
lesser amounts to the north and west. Flooding concerns are not
expected with this system. A persistent onshore flow over the next
few days, coupled with mostly cloudy to overcast skies will result
in high temperatures being at or slightly below average with highs
Wednesday and Thursday in the low to middle 70s. Some areas to the
north and west may rise into the middle to upper 70s Wednesday,
assuming any precipitation remains closer to the coast.

&&

.LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/...
There was no significant change to the long term forecast
Thursday night through early next week.

*Key Points*

*Unsettled conditions continue with lingering chances of showers,
 especially closer to the coast, for the end of the week with
 low pressure lingering south of Long Island.

*Improving conditions should begin to occur Saturday, but
 especially Sunday into early next week as high pressure builds
 in from the northeast.

*Temperatures start out near to slightly above normal Friday
 into Saturday, but will trend slightly below normal Sunday
 into early next week.

Slow moving upper trough/closed low will remain over the
northeast Thursday night through Friday. The modeling has been
having a difficult time trying to resolve the location of a
broad low pressure associated with the trough. The overnight 00z
9/17 runs largely kept the low far enough south off the
Delmarva that the majority of the showers would stay offshore.
However, some of 12z 9/17 guidance has shown a bit a of a north
shift with the low, which would serve to keep some potential of
showers into Friday. The deterministic NBM PoPs Thursday night
through Friday are largely in the slight chance category except
for some chance PoPs near the immediate coast. Bumped NBM PoPs
up about 10 percent given some of the new global deterministic
and ensemble guidance. The result is a chance of showers
Thursday night for much of the area with just a chance near the
coast on Friday and slight chance elsewhere. The upper trough
should begin shifting south and east Friday night into Saturday,
helping push the surface low further away from the area.

Dry weather likely returns Saturday, but some lingering clouds
are possible. Coverage of clouds should diminish further as
ridging begins to build aloft on Sunday. Surface high pressure
over southeast Canada builds down across the northeast into
early next week. The high may then shift towards the Maritimes
on Tuesday as the ridge axis slides off the New England coast.

Highs will be in the 70s on Friday, warmest across the western half
of the area. Temperatures begin to trend down beginning Saturday but
especially Sunday into early next week as cooler air advects south
in associated with the building high pressure. High temperatures
Sunday into early next look to reach the upper 60s to low 70s,
slightly below normal for this time of year. It may also remain
breezy, especially near the coast due the pressure gradient from
the building high to the northeast and departing low pressure.

&&

.AVIATION /05Z WEDNESDAY THROUGH SUNDAY/...
High pressure will remain centered off the New England coast
through tonight, weakening late tonight into Wednesday as low
pressure to our south slowly approaches.

VFR. IFR stratus was beginning to develop and move into
southeastern Connecticut and the Twin Forks, and may expand to
some extent westward into late tonight and early morning hours.

MVFR/IFR, mainly ceilings, develops into the overnight,
returning to VFR late Wednesday morning into the afternoon.
There are timing uncertainties with the development and then
dissipation of MVFR/IFR. There is a chance of showers mid to
late afternoon Wednesday, with a low chance of MVFR.

Light E/NE flow tonight increasing to 10-15kt Wednesday
afternoon.

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

Timing of MVFR onset may be off by a few hours. IFR is possible
late, but low confidence in extent of lower categories,
especially for terminals further west.

OUTLOOK FOR 06Z THURSDAY THROUGH SUNDAY...

Wednesday night through Friday: Periods of rain/showers
possible with with MVFR or lower conditions. NE-N gusts 20-25kt
possible mainly Thursday through Friday.

Saturday: Slight chance of showers with MVFR early in the
morning, then VFR. NE gusts around 25kt possible.

Sunday: VFR. NE gusts 20-25kt possible.

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

&&

.MARINE...
Increased easterly flow and waves will result in SCA conditions on
the ocean zones through at least Wednesday morning, possibly
extending into the day on Thursday. Wave heights near 5 feet
with occasional marginal gusts near 25kt will be possible with
an approaching coastal low remaining south of the area through
the middle of the week.

Marginal SCA conditions are possible Thursday night. A more
prolonged period of SCA conditions is possible on the ocean Friday
into the weekend as seas build and wind gusts on the ocean likely
reach close to 25 kt. The non-ocean waters should remain below SCA
levels.

&&

.HYDROLOGY...
No hydrologic concerns with showers through Thursday with rainfall
amounts less than an inch. Locally higher amounts possible.

There are no hydrologic concerns through the weekend.

&&

.TIDES/COASTAL FLOODING...
Astronomical tides are running high this week due to this evenings
full moon. Increasing E flow will then help keep tide levels
elevated through the rest of the week and potentially into the
upcoming weekend.

Localized minor flooding is expected with high tide Wednesday
morning across the south shore back bays and across the S
Westchester and S Fairfield coast. Have issued a Coastal Flood
Statement for these locations. Minor coastal flooding may become
more widespread with subsequent high tide cycles Wednesday night
through the end of the week. A few locations could touch or exceed
moderate flooding benchmarks at the end of the week/early weekend,
especially for some of the more vulnerable locations of the south
shore back bays. This likely hinges on how much tidal piling occurs
and the strength of the easterly flow over the region. Tide levels
could be held down if the onshore flow is weaker or the wind
direction ends up more northerly.

A high rip current risk for ocean beaches continues through
Wednesday evening. A high rip current risk appears likely to remain
Thursday into the upcoming weekend with rough seas due to increasing
easterly flow.

&&

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

&&

$$

SYNOPSIS...DS/MW
NEAR TERM...DS/MET/MW
SHORT TERM...MW
LONG TERM...DS
AVIATION...BR/MET
MARINE...DS/MW
HYDROLOGY...DS/MW
TIDES/COASTAL FLOODING...