okx-afd on 2024-11-21

370
FXUS61 KOKX 210832
AFDOKX

Area Forecast Discussion
National Weather Service New York NY
332 AM EST Thu Nov 21 2024

.SYNOPSIS...
-- Changed Discussion --Strengthening low pressure moves in from the south today and
meanders over the Tri-State area through Friday before shifting
northeast Friday night. The low will move towards the Canadian
Maritimes on Saturday and then tracks slowly northeast through
Monday. At the same time, weak high pressure builds in from the
west. A weak frontal system will then pass through the area Monday
night into Tuesday, followed by high pressure for the middle of next
week.-- End Changed Discussion --

.NEAR TERM /THROUGH FRIDAY/...
-- Changed Discussion --A low pressure system is expected to continue to move into the area
today from the south as a closed upper to low our west begins to
move eastward towards area. An axis of heavier rainfall with rain
rates of 0.5-0.75"/hr associated with a tongue of higher PWATs and
forcing is moving west to east and is expected to exit east by
midday.

Rainfall is expected to continue through the day today, but aside
from the morning showers, the rain is expected to be lighter in
nature, with a few moderately heavy showers possible, but isolated.

Gusty easterly winds developed overnight and are likely to remain in
place through the day today, primarily along coastal areas, becoming
more northerly by the afternoon today. Maximum gusts will be between
25 and 35 mph.

CAMs and regional models have diverged somewhat on the position of
the movement of the low tonight. Some of the CAMs bring the center
of the low just north of our area and a little to the east into the
early night before having it retrograde to our west in Upstate New
York while other just stick with tracking the low to our northwest.
The more northeasterly track, regardless will only occur this
evening into early tonight before bumping west. With the low
tracking north of us this evening, cooler air will take over this
evening with temperatures near or below freezing in interior
locations north and west of NYC. Prior to this, temperatures will be
in the 40s. A transition from rain to snow is expected this evening
for interior areas north and west of NYC, but given the warm
temperatures prior, snowfall may struggle to accumulate. Its
possible we could see a few heavy bands of snow with snowfall rates
around 1-2"/hr this evening into early tonight indicated by the 00Z
HREF and a saturated dendritic growth zone before the precip gets
cut off by a dry pocket of air that moves in when the low
retrogrades westward into upstate New York. This dry air is easiest
to see when looking at model soundings or at model 700 mb relative
humidity. Higher elevations in interior locations northwest of NYC
will most likely see accumulations of 1-4 inches. However, most of
the interior northwest of NYC is at lower elevations where only a
trace to 0.5" is expected due to warmer ground melting the snow and
a short wind for snow banding before the precip becomes much lighter
from dry air intrusion. Snow ratios are also expected to be on the
low side, further contributing to lower snow accumulations compared
to what some of the CAMs are producing with 10:1 Snowfall.

At the same time, any light showers may become more intermittent and
sparse for areas east of NYC as the low travels farther away. 25-35
mph wind gusts also make a S/SW shift this evening into tonight
under an increasing pressure gradient as the low moves to our
northwest.

The upper-low to our west captures the surface low on Friday morning
leading to a stacked low that moves into central and eastern PA. The
stacked low then pushes back east and over our area Friday
afternoon. This will lead to more scattered rain, but at this point,
the system will be moisture starved, so expecting rain to be on the
lighter side. Total liquid QPF for the event is expected to be
closer to 2-2.5 inches for the western CWA and 1.5-2 inches for the
eastern areas of the CWA. The majority of this is expected to fall
today into early tonight. Highs on Friday will be cool in the low-
40s to low-50s, but with low-40s expected in the interior, any
snowfall that accumulated Thursday evening/night will melt under
additional rainfall.

Due to the position of the low moving over the area, winds are
expected to weaken.-- End Changed Discussion --

.SHORT TERM /FRIDAY NIGHT THROUGH SATURDAY NIGHT/...
-- Changed Discussion --Friday evening, low pressure moves west to east across our area
before transitioning to a position off the coast of New England
later on Friday night. This will lead to rain tapering off west to
east through Friday night.

As the low positions itself to our northeast Friday night eventually
moving into the Canadian Maritimes late on Saturday, high pressure
is expected to gradually build in from the southwest with an upper-
level ridge approaching from the west. This will lead to the winds
turning, becoming northwest late Friday night and increasing in
speed late Friday night into Saturday from an increased pressure
gradient. Wind gusts may start off around 20-25 mph Saturday
morning, peaking Saturday night around 35 mph.

Partly cloudy skies and dry weather are expected by Saturday morning
following the low`s exit. Temperatures Friday night will drop into
the low to upper-30s before warming to the low-50s/upper-40s
Saturday afternoon. Given the increased winds, lows on Saturday
night will be slightly warmer in the upper-30s to mid-40s.-- End Changed Discussion --

.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
-- Changed Discussion --* Gusty NW flow and near normal temperatures behind departing storm
system this weekend.

* Weak frontal system to move through the area Monday night into
Tuesday.

Deepening low pressure approaching the Canadian Maritimes on
Saturday will gradually lift northeast through the weekend into
early next week, while weak high pressure builds east from the Ohio
Valley. It will be dry during this time with a strong NW flow. Gusts
will approach 30 mph in the afternoon, with brief higher gusts up to
40 mph possible. Expect slightly warmer temperatures on Sunday.

A nearly zonal upper flow to start the week will send a fast moving
low NE across the Ohio Valley and Lower Great Lakes Monday, to the
north of the area on Tuesday. This will send a weak frontal system
through the area Monday night into Tuesday morning with a low chance
for rain. High pressure then builds in through midweek. Temperatures
Monday and Tuesday will be a few degrees above normal, but then cool
back down Tuesday night into Wednesday at or just below normal.-- End Changed Discussion --

.AVIATION /08Z THURSDAY THROUGH MONDAY/...
-- Changed Discussion --Low pressure intensifies south of Long Island this morning and
afternoon. The low will then shift over the area tonight and meander
nearby on Friday.

Mainly MVFR to start with moderate rain moving across the terminals
from west to east early this morning. There may be brief pockets of
heavy rain. Conditions should gradually lower to IFR this morning,
especially after day break. The intensity of the rain should become
lighter by late morning and continue into the afternoon. There may
be another period of moderate rain this evening/tonight, but the
exact location remains uncertain. The rain should mix with or change
to a period of wet snow well NW of the NYC metro terminals across
the interior of the Lower Hudson Valley overnight/early Friday
morning.

Low confidence wind forecast to start the TAF period. Winds are
expected to be E-NNE and gradually settle to NNE for most terminals
this morning. The flow should then become N late morning into the
afternoon and then shift to the NW late afternoon into the evening.
A SW flow should develop as the low shifts to the north or northwest
of the area late tonight. Frequency and magnitude of gusts remains
uncertain, but there should be gusts 20-25 this morning and
afternoon. Gusts in the west flow this evening may increase to 25-
30kt.

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

Amendments expected for changing flight categories through the TAF
period. MVFR may persist several hours longer this morning before
IFR develops.

Amendments expected for wind direction and frequency and magnitude
gusts this morning and afternoon.

OUTLOOK FOR 06Z FRIDAY THROUGH MONDAY...

Late Thursday Night...IFR to MVFR with periods of rain, possibly
mixed with wet snow well NW of NYC metro. Rain ending and becoming
VFR at the NYC terminals and Long Island early Friday. SW gusts 15-
25kt.

Friday...MVFR-VFR with rain possible. Wet snow may mix in N and W of
the NYC metro. S-SW gusts 15-20kt possible.

Saturday...MVFR possible. WNW winds gusting 20-30kt.

Sunday...VFR. WNW winds gusting to 20-30kt.

Monday...VFR.

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

.MARINE...
-- Changed Discussion --All waters remain under a Small Craft Advisory through midday Friday
due to winds gusting between 25-32 kts and waves between 6-10
feet on ocean waters. Winds drop below SCA criteria for all
waters after midday Friday, but 4-6 foot seas remain on the
ocean through Friday afternoon with a Small Craft Advisory in
place for ocean waters through this time.

Following Friday afternoon, wind and waves will remain below SCA
criteria until Saturday morning. SAturday morning through Saturday
night all waters reach SCA criteria for winds gusting between 27 kts
and 32 kts while ocean waves build back to 6-8 foot waves.

Both early today and Saturday, a few gales are possible, but for
now, still expecting any gale-force winds to remain isolated or too
short in duration.

SCA seas and winds across the waters, with the potential for Gale
force gusts continue through Sunday afternoon. Thereafter, high
pressure builds in from the west with decreasing winds and seas
Sunday night into Monday.-- End Changed Discussion --

.FIRE WEATHER...
-- Changed Discussion --A wetting rainfall through Friday will help mitigate short term
concerns for fire danger, but will not be enough to lift us from
long term drought.-- End Changed Discussion --

.HYDROLOGY...
-- Changed Discussion --Overall storm total rainfall this morning through Friday night is
2.0-2.5 inches west of the Hudson, ranging closer to 1.5-2.0 inches
to the east. Most of this, along with any potential impacts, is
expected to occur through midday today with the remainder of the
rain being too light to cause any issues. There could be minor
flooding associated with clogged drains. Otherwise, no hydrologic
impacts are expected given the recent dry weather and progressive
nature of any heavier rainfall tapering off by this afternoon.

No hydrologic impacts are expected this weekend through the middle
of next week.-- End Changed Discussion --

.TIDES/COASTAL FLOODING...
-- Changed Discussion --An intensifying low pressure south of Long Island will bring a 2 to
3 ft surge, especially across the coasts of Long Island and Southern
Connecticut. 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. This is especially important for the
Lower NY Harbor as there is a fine line with the wind shift near
high tide. If the easterly flow lasts a bit longer water may pile
more into the NY Bight area.

Coastal Flood Advisories remain in effect for widespread minor
flooding across the south shore back bays of Nassau, Great South
Bay, eastern LI Bays as well as along much of the north shore.
Advisories also remain in effect across southern Fairfield and
southern Westchester. The remainder of the area resides under a
coastal flood statement as water levels approach or just exceed
minor coastal flood benchmarks. For the upper harbor around the
Battery, water levels should remain low enough that no statement was
issued.

No additional coastal flooding is anticipated the rest of the week
into the upcoming weekend.-- End Changed Discussion --

.OKX WATCHES/WARNINGS/ADVISORIES...
-- Changed Discussion --CT...Coastal Flood Advisory from 1 PM to 5 PM EST this afternoon
for CTZ009.
NY...Coastal Flood Advisory from 1 PM to 5 PM EST this afternoon
for NYZ071.
Coastal Flood Advisory from 11 AM this morning to 5 PM EST
this afternoon for NYZ078>081.
Coastal Flood Advisory from 10 AM this morning to 2 PM EST
this afternoon for NYZ179.
NJ...None.
MARINE...Small Craft Advisory until 1 PM EST Friday for ANZ331-332-335-
338-340-345.
Small Craft Advisory until 7 PM EST Friday for ANZ350-353-355.-- End Changed Discussion --

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