okx-afd on 2025-03-18

039
FXUS61 KOKX 181923
AFDOKX

Area Forecast Discussion
National Weather Service New York NY
323 PM EDT Tue Mar 18 2025

.SYNOPSIS...
-- Changed Discussion --High pressure will be in control through Wednesday. The high
shifts east Wednesday night ahead of the next approaching cold
front on Thursday. A coastal low develops along the cold front
and will impact the area Thursday night through Friday. High
pressure builds in very briefly Friday night before a weak area
of low pressure moves through Saturday into Saturday night. High
pressure returns Sunday, with another frontal system expected
to move through early next week.-- End Changed Discussion --

.NEAR TERM /THROUGH WEDNESDAY/...
-- Changed Discussion --An upper level ridge and associated surface high will continue
to build over the region tonight. The offshore low pressure
will also continuing drifting further east. High clouds
associated with the offshore low will stream across eastern
portions of Long Island and southeast Connecticut this evening.
The building ridge aloft will gradually shift the axis of these
clouds offshore tonight leaving behind mainly clear skies across
the entire area. Weak winds, dry air, will combine with the
clear skies for ideal radiational cooling conditions, especially
outside of the NYC metro. Lows will range from the upper 20s
and low 30s inland and across LI Pine Barrens to the mid and
upper 30s elsewhere. Lows in the NYC metro should only fall into
the low 40s.

Ridging will remain overhead for much of Wednesday. The surface
high begins to shift to the east and the low level flow is
weak. A fairly quick warm up in the morning and early afternoon
will lead to sea breeze development through the afternoon. The
axis of the ridge also begins shifting to the east late in the
day with SW flow starting to increase well ahead of the next
amplifying trough over the Plains. This increase in SW flow will
bring in some high clouds late. Highs in the upper 50s to
around 60 will be reached by early afternoon across much of Long
Island, coastal Connecticut, and southern portions of the NYC
metro. Further inland highs in the lower to middle 60s are
forecast with a later timing of the sea breeze.-- End Changed Discussion --

.SHORT TERM /WEDNESDAY NIGHT THROUGH THURSDAY/...
-- Changed Discussion --Ridging will exit offshore Wednesday night into Thursday as
the aforementioned shortwave trough quickly approaches. Low
level warm advection will increase Wednesday night. Increasing
dew points and warmer air above the surface should begin the
development of low clouds over the colder ocean. These clouds
will likely overspread the area Wednesday night. Areas of fog
are also possible especially closer to the coast early Thursday
morning. Low confidence at this time if any of the fog will
become dense and whether or not there will be drizzle. Model
precip fields indicate some trace amounts of QPF, but this could
just be a signal for the low clouds overspreading the area.
Lows Wednesday night will be milder and generally in the lower
to middle 40s with a few interior spots dropping into the 30s.

Most of the daytime hours on Thursday will be dry. The upper trough
rapidly approaches with its associated frontal system late in the
day. Chances for showers begin to increase towards sunset from the
NYC metro on west. Otherwise, low clouds may persist for a portion
of the morning before diminishing. It is quite possible that
portions of Long Island and southeast Connecticut remain under low
clouds for a good portion of the day with the warmer air aloft
continuing to move over the colder ocean. Temperatures will be
cooler compared to Wednesday and only in the lower to middle 50s for
most spots with potential of some upper 50s in the usual warmer
spots. Temperatures may struggle to rise above 50 degrees near the
coast and eastern Long Island/southeast CT if the low clouds hang on
longer than currently forecast.-- End Changed Discussion --

.LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/...
-- Changed Discussion --Key Points:

* Moderate to locally heavy rain possible Thursday night into
Friday morning along with the potential for some snow across
the interior

* Gusty NW flow behind the system could exceed 40 mph at times
Friday

* Next chance for widespread precipitation then looks to arrive
Monday into Tuesday of next week

The long term period starts off with a deep trough just to our
west. Low pressure at the surface will be centered somewhere
well to our north in eastern Canada while an associated cold
front extends southward just to our west. As this boundary
approaches, a coastal low looks to develop along it right over
or just south of our area. The guidance is in good agreement up
to this point. Model solutions start to diverge with how quickly
the low departs. The GFS continues to be the slowest, and has
the low lingering nearby through Friday. The ECMWF remains very
progressive and the Canadian is somewhere in between. Something
to keep an eye on for the next few forecast cycles is the GEFS
member low locations. A cluster of members have trended a bit
slower and farther southwest with the coastal low in the latest
12z run. The GFS deterministic solution would allow for precip
to be lingering while colder air moves in behind the system.
This would be the snowiest solution. A faster system will likely
lead to all plain rain. Given the spread, for now stuck with a
few tenths of accumulation across the interior, with total QPF
everywhere ranging from 0.50 to 0.75 inches. It is also worth
noting that a slower system would lead to an increase in QPF. At
this time there are no hydrologic concerns.

Regardless of speed of departure, there is pretty high confidence
in gusty northwest winds behind this system. As the low deepens
it is reasonable at this time to say we can see gusts exceed 40
mph. Model soundings agree with periods of mixing up to 900mb
on Friday. This could even allow for a brief window of Advisory
level gusts. Have trended the forecast up slightly for now, but
this trend may continue.

Brief surface ridging builds in Friday night and will allow
for winds to lower a bit. A weak area of low pressure passes to
the north on Saturday but will likely not bring any precip to
our area. The next chance for widespread precip looks to be with
another frontal system early next week. There may be enough
cold air around for some snow to mix in at the onset across the
interior, but this will likely be a mostly plain rain event.-- End Changed Discussion --

.AVIATION /19Z TUESDAY THROUGH SUNDAY/...
VFR as high pressure to the west builds in through tonight,
then slides just east on Wednesday.

NNW through NNE winds 10 kt or less will continue to diminish
this afternoon. SE sea breeze already came in at KBDR, and it
is possible that the NYC metros and other coastal terminals
could see a light SE sea breeze this evening from about 00Z-04Z
give/take an hour. After that a light NE flow should resume,
becoming SE 5-10 kt in the afternoon.

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

Terminals could see a period of light SE flow this evening from
about 23Z-24Z until 03Z-04Z.

.OUTLOOK FOR 18Z WEDNESDAY THROUGH SATURDAY...

Wednesday afternoon: VFR.

Wednesday night: IFR/LIFR cigs possible late at KISP/KGON, and
MVFR elsewhere.

Thursday: IFR/LIFR cigs possible late at KISP/KGON, and
MVFR elsewhere, gradually improve to VFR by late morning or
midday. SE winds G20kt in the afternoon.

Thursday night: IFR cond likely in rain. Precip could mix with
snow late at KSWF. NW winds G20-25kt late from the NYC metros
north/west.

Friday: MVFR cond possible in the morning at the CT/Long Island
terminals. NW winds G30-40kt.

Friday night: VFR. NW winds G20-25 kt in the evening.

Saturday: VFR. SW winds G20kt in the afternoon at the NYC
metros.

Sunday: VFR. NW winds G20kt.

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

.MARINE...
-- Changed Discussion --Winds have continued subsiding on the waters this afternoon
with lingering potential of gusts up to 20 kt on the ocean east
of Moriches Inlet and eastern LI Bays and Sound. These winds
will continue to diminish through this evening. Seas have also
subsided below 5 ft on the ocean west of Fire Island Inlet. Have
therefore cancelled the Advisory for these waters. Seas east of
Fire Island Inlet will remain 5-6 ft through tonight and may
linger near 5 ft east of Moriches Inlet through Wednesday
morning. Otherwise, conditions will remain below SCA levels
through much of Wednesday night. Seas may begin building back
towards 5 ft on the ocean late Wednesday night, but more likely
on Thursday ahead of an approaching frontal system. Winds will
also increase on Thursday and could approach 20-25 kt late in
the day on the ocean west of Fire Island Inlet.

As a coastal low deepens near the area, winds will strengthen
Thursday night into Friday morning. Gale force gusts are possible
by Friday morning on all waters and have continued a mention of
this in the HWO. During this time, seas on the ocean waters may
reach 8-10 feet. Sub-SCA conditions are expected to return on
Saturday and could last through early next week. There is some
potential for brief SCA conditions on Monday with another
frontal system moving through.-- End Changed Discussion --

.HYDROLOGY...
-- Changed Discussion --
No hydrologic impacts are expected through early next week.-- End Changed Discussion --

.OKX WATCHES/WARNINGS/ADVISORIES...
-- Changed Discussion --CT...None.
NY...None.
NJ...None.
MARINE...Small Craft Advisory until 11 AM EDT Wednesday for ANZ350.
Small Craft Advisory until 6 AM EDT Wednesday for ANZ353.-- End Changed Discussion --

SYNOPSIS...DS/JT
NEAR TERM...DS
SHORT TERM...DS
LONG TERM...JT
AVIATION...BG
MARINE...DS/JT
HYDROLOGY...DS/JT