okx-afd on 2024-11-21

744
FXUS61 KOKX 211514
AFDOKX

Area Forecast Discussion
National Weather Service New York NY
1014 AM EST Thu Nov 21 2024

.SYNOPSIS...
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.

.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. 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. Western
Passaic, Orange and Putnam Counties are now highlighted in the
HWO for this potential. However, most of the interior northwest
of NYC is at lower elevation and only a trace to 0.5" is
expected due to warmer ground melting the snow and a short
window 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/...
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.

.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
* 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.

Strong low pressure will linger over the Canadian Maritimes
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 Sunday afternoon, with
Expect slightly warmer temperatures on Sunday compared to
Saturday.

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.

.AVIATION /15Z THURSDAY THROUGH MONDAY/...
-- Changed Discussion --Low pressure intensifies south of Long Island through this
evening. The low will then shift over the area tonight and
meander nearby on Friday.

Mainly MVFR in rain and/or drizzle to start the TAF period.
Conditions should fall to IFR with light rain or showers continuing
afternoon. There may be another period of moderate...possibly
heavier rain this evening/tonight. The rain should begin mixing
with or change to a period of wet snow well NW of the NYC metro
terminals, mainly across the interior of the Lower Hudson
Valley, overnight/early Friday morning. Flight categories may
slowly improve to MVFR overnight.

N-NE winds 10-15 kt to start the period. Gusts 20-25 kt will
likely be occasional but more frequent gusts are expected this
afternoon with the likelihood of gusts 25-30 kt this evening,
potentially into tonight as winds shift to the NW and then W-SW
into early Friday morning.

...NY Metro (KEWR/KLGA/KJFK/KTEB)TAF Uncertainty...
Amendments expected for changing flight categories through the
TAF period. The start of prevailing IFR conditions may be off
by 1-3 hours.

Amendments likely for timing of wind shifts and wind gusts.

Additional amendments likely this evening due to timing of
heavier precipitation and turnover to mixed precipitation north
and west of city terminals.

OUTLOOK FOR 12Z FRIDAY THROUGH MONDAY...

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...
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.

.FIRE WEATHER...
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.

.HYDROLOGY...
Overall storm total rainfall 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 through the middle of next week.

.TIDES/COASTAL FLOODING...
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.

.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 until 5 PM EST this afternoon for
NYZ078>081.
Coastal Flood Advisory until 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/JT
SHORT TERM...BR
LONG TERM...DW
AVIATION...DS
MARINE...BR/DW
FIRE WEATHER...
HYDROLOGY...BR/DW
TIDES/COASTAL FLOODING...