okx-afd on 2024-11-20

830
FXUS61 KOKX 201451
AFDOKX

Area Forecast Discussion
National Weather Service New York NY
951 AM EST Wed Nov 20 2024

.SYNOPSIS...
-- Changed Discussion --High pressure weakens through today. Strengthening low pressure
moves in from the south tonight and meanders over the Tri-State
area through Friday before shifting northeast Friday night. The
low will move towards the Canadian Maritimes on Saturday with
high pressure building in for Sunday into Monday. A weak frontal
system may then approach on Tuesday.-- End Changed Discussion --

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
-- Changed Discussion --The forecast remains mainly on track with minor changes made
with this update.

A longwave ridge aloft gradually weakens today as a deep trough to
our west slowly nudges eastward. Partly to mostly sunny over
roughly the eastern half of the forecast area with partly to
mostly cloudy conditions farther west. We`ll keep things dry
through the day. Highs should reach the mid-50s to low-60s.-- End Changed Discussion --

.SHORT TERM /6 PM THIS EVENING THROUGH FRIDAY NIGHT/...
A deep trough gradually moves into the region from the west
Wednesday night as a deep low spins over the Great Lakes. Positive
vorticity advection along the low`s periphery spins up a new low off
the New Jersey coast on Thursday. This low continues to strengthen
through Thursday, then gradually occludes Thursday night into Friday
night. It is expected to spin nearby, possibly pushing west of the
area as it continues occluding on Friday before eventually moving
into New England or off the New England coast Friday night.

As the coastal low develops Wednesday night under a deepening trough
aloft centering itself over the area, cloudy skies take over with
wind speeds increasing from the increased pressure gradient. These
stronger winds may linger through Friday night. As the low develops
to our south early Wednesday night, it also attempts to center it
self over the area as it moves along a frontal boundary. Moisture
also ends up getting advected into the area, PWATs peaking Wednesday
night between 1-1.15" based on the latest guidance. This is around
the 90th percentile per SPC`s Sounding Climatology page. With nearby
sources for lift and positive vorticity advection aloft, along with
strong moisture advection, expecting a good amount of rain Wednesday
night into early Thursday morning that could drop around 1-2 inches,
with highest amounts near NE NJ, NYC metro, and Long Island. Some
marginal instability may also lead to a slight chance for
thunderstorms late Wednesday night into Thursday morning.

Following Thursday morning, drier air moves. Given the low remains
in the area, precipitation is expected to continue, but will be on
the lighter side of things. Unfortunately 00Z deterministic global
and regional models differ in placement of the low Thursday
afternoon through Friday afternoon, with some lingering the low over
the area while others retrograde the low to our northwest Thursday
night into Friday morning. Overall, precip chances are expected to
remain through Friday.

Cool air really takes hold Thursday night with lows in the upper-to-
lower 30s. As the low enters its occlusion phase on Thursday night
mid-level warm air advection and FGEN really pick up on the western
side of the low which could lead to higher snow totals. These higher
snow totals, however, are expected much further to our west. Given
the location of the low, we should mainly see light rain Thursday
night, with some areas of higher terrain in Orange and Putnam
picking up a trace to 2 inches, while valley ares will see primarily
rain.

Precipitation chances continue into Friday as the low lingers
over the area with high temperatures in the low-to-upper 40s.

Models are in decent agreement on the weakening low eventually
making its exit into New England or off the New England coast Friday
night leading to tapering chances for rain. Overall storm total
rainfall Wednesday night through Friday night is 2.5-3 inches for the
western half of the CWA with chances tapering towards the eastern
half of the CWA totaling closer to 1.5-2 inches. No hydrologic
impacts are expected given the recent dry weather and progressive
nature of any heavier rainfall which appears to be limited to
Wednesday night/Thursday morning. Storm total snowfall is around a
trace to 2 inches primarily for higher terrain areas in Putnam,
Orange and western Passaic counties.

.LONG TERM /SATURDAY THROUGH TUESDAY/...
Deep, closed upper low will begin to lift NNE away from the region
on Saturday and then over the Canadian Maritimes on Sunday. This
will allow for slowly rising heights with a relatively flat ridge
over the northeast on Sunday. The upper flow pattern looks to then
become nearly zonal on Monday. The modeling has been hinting at a
weak shortwave energy approaching the northeast next Tuesday, but
the main troughing will likely reside over the western CONUS.

There may still be some light rain near the coast to start the day.
The system lifts NNE away from the area into Saturday afternoon
allowing for mainly dry conditions. The lingering cold pocket aloft
should still support mostly cloudy conditions with some potential of
partial clearing late in the day as heights rise more significantly.
High pressure starts building to the southwest with the region
between this high and the strong low to the northeast. This will
bring a breezy NW wind with gusts 25 to 30 mph. The center of the
high will remain across the southeast, but ridge up into the
northeast Saturday night into Sunday. There will likely continue be
a strong enough pressure gradient and mixing on Sunday for continued
breezy conditions, especially the eastern half of the area. The high
weakens on Monday followed by an approaching weak frontal system on
Tuesday. The forecast is mostly dry Sunday through Tuesday, but will
carry a slight chance on Tuesday with the weak frontal system.

Near seasonable temperatures are forecast on Saturday with
temperatures trending above normal Sunday into early next week.

.AVIATION /14Z WEDNESDAY THROUGH SUNDAY/...
-- Changed Discussion --High pressure will gradually move east of the terminals through this
evening. A frontal system approaches tonight with low pressure
strengthening just south of Long Island tonight.

Mainly VFR through 00z, although a few of the western most terminals
may have brief MVFR with cigs hovering at 030-035 at times late this
morning. Occurrence should be infrequent, thus not included in TAFs.
Conditions will then lower to prevailing MVFR 02-05z with some light
rain possible. IFR should quickly develop after 06z with moderate to
heavy rain possible through early Thursday morning, especially for
NYC metro and Lower Hudson Valley terminals. A rumble of thunder
cannot be ruled out. The moderate to heavy rain will shift east of
the NYC terminals around 12z, but a steady light rain persists
through the morning. Some local LIFR is possible.

Light winds into the afternoon with a NE direction most likely
becoming E-SE this afternoon. E winds increase this evening and
become gusty. Gusts 20-30 kt are possible overnight into early
Thursday morning.

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

Amendments likely for timing of lowering flight categories as
well as developing rain this evening into tonight.

Amendments likely for winds late tonight into Thursday,
especially with magnitude and duration of gusts.

OUTLOOK FOR 12Z THURSDAY THROUGH SUNDAY...

Thursday...IFR, possibly LIFR early, with rain, moderate to
heavy at times early in the morning NE gusts 20-30kt. Wind
direction likely becomes NW across NYC to Lower Hudson Valley
Terminals in the afternoon.

Thursday Night...IFR to MVFR with periods of rain, possibly mixed
with wet snow well NW of NYC metro. SW gusts 20-25 kt.

Friday...Mainly MVFR with rain possible. Wet snow may mix in
well NW of the NYC metro. S-SW gusts 15-20kt possible.

Saturday...MVFR possibly becoming VFR late. WNW winds gusting 20-
30kt.

Sunday...VFR. W-NW winds gusting to 20-30kt.

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

.MARINE...
-- Changed Discussion --A Small Craft Advisory has been issued for ocean waters overnight
tonight through Thursday night. There is a chance it could be
extended.

Sub-SCA conditions are expected today. Tonight, Low pressure
develops and strengthens over the waters through Thursday. This will
lead to increasing winds and building seas. Wind gusts 25-30 kt are
likely Wednesday night through Thursday night. There is also
potential of gale force gusts. For now, gale-force gusts should
remain isolated and limited to a small time window Thursday morning,
but will continue to mention the potential in the HWO. Waves will
reach 5 feet on ocean waters early Thursday morning, peaking at 10
feet Thursday night. SCA conditions remain through Friday night.

SCA conditions are likely to continue on the waters this weekend as
the low pressure departs to the NE and high pressure builds in from
the south.-- End Changed Discussion --

.FIRE WEATHER...
Light winds are expected Wednesday along with minimum RH values 45-
60 percent. AN SPS has been issued for S CT based on collab with
CT fire partners. A substantial wetting rainfall is then
expected Wednesday night through Friday which should help
mitigate short term concerns for fire danger, but may not be
enough to lift us from long-term drought.

.HYDROLOGY...
Overall storm total rainfall Wednesday night through Friday night is
2.5-3 inches for the western half of the CWA with chances tapering
towards the eastern half of the CWA totaling closer to 1.5-2
inches. No hydrologic impacts are expected given the recent dry
weather and progressive nature of any heavier rainfall which appears
to be limited to Wednesday night/Thursday morning.

No hydrologic impacts are expected this weekend through early next
week.

.TIDES/COASTAL FLOODING...
Astronomical tides will continue to fall through the end of the
week. No coastal flooding is expected with high tide today. However,
an intensifying low pressure south of Long Island late tonight into
Thursday will bring a surge of 2 to 3 ft, especially across the
coasts of Long Island and Southern CT. The exact location/track of
the low will be important to the magnitude and duration of the surge
along with it coinciding with the timing of high tide.

Guidance has been trending higher with the tide levels with the late
Thursday morning into Thursday afternoon high tide. Confidence is
highest for minor coastal flooding benchmarks to be exceeded across
the south shore back bays, Great South Bay, and eastern LI Bays as
well as along much of the north shore. Minor coastal flooding also
looks widespread across southern Fairfield and southern Westchester.
Coastal Flood Advisories have been issued for these areas for the
late Thursday morning into Thursday afternoon high tide. For N
Nassau and N Queens as well as southeastern coast of CT, any minor
flooding looks localized and have gone with a statement. The surge
may peak for the NY harbor earlier than high tide with the flow
becoming westerly on the backside of the low, which should prevent
any coastal flooding. Have held off on any statements/advisories and
will let subsequent shifts reevaluate.

.OKX WATCHES/WARNINGS/ADVISORIES...
CT...Coastal Flood Advisory from 1 PM to 5 PM EST Thursday for
CTZ009.
NY...Coastal Flood Advisory from 1 PM to 5 PM EST Thursday for
NYZ071.
Coastal Flood Advisory from 11 AM to 5 PM EST Thursday for
NYZ078>081.
Coastal Flood Advisory from 10 AM to 2 PM EST Thursday for
NYZ179.
NJ...None.
MARINE...Small Craft Advisory from 11 PM this evening to 7 AM EST
Friday for ANZ331-332-335-338-340-345-350-353-355.

SYNOPSIS...JC/DS
NEAR TERM...JC/BR
SHORT TERM...BR
LONG TERM...DS
AVIATION...JE/DS
MARINE...BR/DS
FIRE WEATHER...
HYDROLOGY...BR/DS
TIDES/COASTAL FLOODING...