000
FXUS61 KOKX 201810
AFDOKX
Area Forecast Discussion
National Weather Service New York NY
110 PM EST Mon Nov 20 2023
.SYNOPSIS...
High pressure builds in from the northwest through tonight.
The high moves off the New England coast Tuesday as low
pressure approaches from the southwest. The low moves through
the region Tuesday night into early Wednesday. High pressure
will gradually build into the area from the south and west
Wednesday night into Thanksgiving. The high pressure area will
remain in the region Friday but will weaken. Low pressure will
potentially impact the area Friday into Saturday from the south.
High pressure returns for the end of the weekend.
&&
.NEAR TERM /THROUGH TONIGHT/...
-- Changed Discussion --
The forecast remains on track. SLightly adjusted hourly
dewpoints through the evening to account for current
observations and trends.
Deep-layered ridging occurs during this period with the center of
surface high pressure shifting east and reaching New England late
tonight. Sunny and dry for today with highs 5-8 degrees below
normal. Cirrus thickens tonight and prevents ideal radiational
cooling, but the airmass is still cold enough in spite of this for
lows to fall to around 20 across the northern zones and Pine Barrens
Region. Freezing temperatures will likely be realized in parts of
the city, Hudson County and Southern Nassau County where the growing
season has not yet officially ended. The cirrus brings a little
uncertainty regarding how cold it gets for these locations, but even
the typically warmer NBM brings freezing temperatures for these
areas. Have upgraded from a Freeze Watch to a Warning for the Bronx,
Staten Island, Hudson County, and Southern Nassau County with enough
confidence. There could be patchy frost that develops in other areas
before the cirrus becomes broken to overcast, but these chances look
to be limited to the northern suburbs.-- End Changed Discussion --
&&
.SHORT TERM /TUESDAY THROUGH WEDNESDAY/...
Low pressure tracks NE into the eastern Great Lakes Region on
Tuesday. Energy then gets transferred to a secondary low, with its
center passing through or very close to the forecast area early
Wednesday morning. The low will be east of us on Wednesday afternoon
with high pressure building in behind it.
Rain chances begin west to east Tuesday afternoon before
becoming likely towards sunset into early evening. There is a
chance for a brief mix of wet snow and rain at the onset across
northern Putnam and Orange counties with no snow accumulation. A
sharpening theta-e ridge axis approaches us from the south and
west with increasing moisture. A low level jet and strong
isentropic lift right ahead of the approaching secondary low
will provide plenty of lift along with divergence in the upper
levels as the left exit region of a jet streak shifts through
during the overnight hours. These ingredients will combine for
periods of moderate to, at times, potentially heavy rainfall
after midnight. The stronger signal for this is generally over
the southern and eastern zones. The heaviest rainfall will
probably be over by sunrise Wednesday west of CT and LI, with
the heavy rainfall potential exiting east of eastern CT and
eastern LI by mid-morning. See the hydrology section below for
additional information and potential impacts. Wednesday
afternoon should be dry for everyone.
One other aspect of this storm system will be winds, particularly
late Tuesday night/early Wednesday morning ahead of the secondary
low passage. 925mb winds for coastal areas during this time are
progged at 45-55kt. With a relatively weak low level inversion in
place, estimating 60-70% of this can mix down to the surface. Some
gusts in the 40-50mph range would therefore be possible. Not enough
confidence in a widespread enough event for a wind advisory, but if
winds gusts were to exceed 45mph, it would most likely occur over
eastern LI. Peak wind gusts for coastal sections are otherwise more
likely to fall in the range of 30-45mph.
Clouds and rainfall will hold high temps in the 40s in most spots
Tuesday. Wednesday will be milder, but breezy with highs generally
in the 50s.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
From large scale model depictions, the jet stream level shows a
departure of a trough and jet streak Wednesday night. This will
be followed by quasi-zonal flow for Thursday through Thursday
night. Then jet streak areas to the north and south of the
region are present Friday into Friday night, which may
potentially phase together for the weekend. By end of the
weekend, there is some model indication of the more southern jet
streak strengthening substantially with a longer wavelength
trough developing across SE Canada.
At the surface, low pressure will continue moving well out of the
region Wednesday night, eventually getting to southeast of the
Canadian Maritimes by early Thursday. High pressure will build into
the local area from the west during this timeframe. For
Thanksgiving, the high pressure area will continue to build in from
the west, but its center remains well to the west of the region.
There will still be a rather steep pressure gradient, keeping gusty
northwest winds in place.
The pressure gradient weakens Friday into the weekend. Low pressure
potentially impacts the region, moving in from the south. Model
differences increase in this part of the forecast with wide
variations of position and strength of the low. Chances for rainfall
are in the forecast Friday through Saturday. Confidence is low with
this forecast from Friday through the weekend.
Otherwise, mainly dry conditions are forecast in the long term.
Temperatures are near normal for highs Thanksgiving and Friday with
below normal highs for the weekend. Forecast lows near normal
Wednesday night and Thursday night, a few degrees above normal
Friday night and below normal for the weekend.
Overall, changes in the long term compared to previous forecast
were to increase POPs, but still within chance, for rain Friday into
Saturday and to make lows Friday night a little warmer.
&&
.AVIATION /18Z MONDAY THROUGH SATURDAY/...
-- Changed Discussion --
High pressure builds to the north of the area tonight and then
off the New England coast Tuesday. Low pressure will approach
from the southwest Tuesday, moving across the area Tuesday night
into Wednesday morning.
VFR conditions are forecast through Tuesday morning with MVFR
conditions developing for the 30h TAF sites Tuesday afternoon
(around 21Z).
With high pressure passing to the north tonight and then offshore
on Tuesday, northerly winds of 5-10kt this afternoon will gradually
veer around to the E by morning, becoming ESE by afternoon and
strengthening to 10-15 G15-20kt. For the 30h TAf sites, gusts
of 20-25kt are forecast by early evening.
...NY Metro(KEWR/KLGA/KJFK/KTEB) TAF Uncertainty...
Amendments not unlikely through tonight.
OUTLOOK FOR 18Z TUESDAY THROUGH SATURDAY...
Tuesday Afternoon: Becoming MVFR. SE winds 10-15 kt G20-25kt by
early evening.
Tue night: IFR with rain. SE winds near 15 to 20 kt. Gusts near
25 to 35 kt. A few higher gusts possible at the coastal terminals,
especially at KGON. Potential for LLWS with forecast 2 kft
winds around 40-50 kt late at night.
Wed: MVFR to IFR early with lingering rain. Rain tapers off late
morning into afternoon with eventual improvement to VFR late.
SW-W winds 10-15 kt with gusts near 20 to 25 kt AM. NW winds
10-15 kt with gusts 15-20 kt PM. Potential for LLWS with
forecast 2k ft winds around 45-50 kt in the morning near KGON.
Thu: VFR with NW to W winds 10-15 kt with gusts 20-25kt. Winds
gradually diminish late day into night.
Fri-Sat: VFR.
Detailed information, including hourly TAF wind component forecasts,
can be found at: https:/www.weather.gov/zny/n90-- End Changed Discussion --
&&
.MARINE...
SCA remains in effect on the ocean east of Moriches Inlet,
primarily for seas, but some gusts to 25 kt are still possible.
This advisory might be cancelled with the next update should
winds and seas continue to trend downward at the rate they have
been recently. Sub-advisory conditions then prevail this
afternoon through a good portion of Tuesday. Low pressure will
then bring increasing winds and seas late in the day into
Tuesday night. A Gale Watch is in effect for all waters Tuesday
night. With only a short period of advisory conditions preceding
the gales, have decided to not issue an advisory stepping up to
the warning. A gusty NW flow follows in the storm`s wake on
Wednesday with advisory level conditions likely on all waters.
For the long term winds Wednesday night through Friday night,
SCA potential and perhaps brief gales possible as well Wednesday
night into Thursday. Otherwise Thursday night through Friday
night, sub SCA conditions are forecast.
For the long term waves Wednesday night through Friday night,
SCA seas for extreme Eastern Long Island Sound Wednesday night
and SCA seas on ocean Wednesday night through Thursday. For
Thursday, SCA seas confined to mainly just ocean, then just
Moriches to Montauk ocean zone for Thursday evening. The other
forecast waters not mentioned will remain below SCA thresholds
for seas. For late Thursday night through Friday night, sub-
SCA conditions forecast for all waters.
Trend with new NWPS, negative with wave heights Wednesday night
through first half of Friday night (through 06Z Sat),
then trends up with wave height 09Z Sat compared to the previous
forecast.
&&
.HYDROLOGY...
No hydrologic impacts are expected through Tuesday afternoon.
Total rainfall from late Tuesday afternoon through Wednesday morning
is expected to range from 1 to 2 inches. The highest amounts are
more likely to occur over NE NJ, NYC, LI and SE CT. Given these rain
amounts with antecedent dry conditions and flash flood guidance,
only minor/nuisance flooding is anticipated. The heaviest rainfall
is anticipated after midnight Tuesday night with the threat of heavy
downpours over for most spots by the start of the Wednesday morning
commute.
No hydrologic impacts are expected Wednesday night through the
weekend.
&&
.TIDES/COASTAL FLOODING...
SE flow increases Tuesday into Tuesday night, allowing for surge to
increase. Total water level increases enough in the forecast to
result in widespread minor coastal flooding.
Some gauges are forecast to go well into the minor coastal flood
category and others are just touching the minor coastal flooding
benchmark. Some locations, particularly in the South Shore Bays of
Long Island, could potentially reach have their total water level
reach moderate coastal flooding.
Just about all coastlines in the forecast region will probably
experience minor coastal flooding with exception of shorelines
around Southern New London CT.
The main high tide cycle of concern regarding this coastal flooding
will be overnight Tuesday night into early Wednesday morning.
With low level winds switching to more westerly flow later
Wednesday into Wednesday night, subsequent high tide cycles are
expected to have total water levels stay below minor coastal
flood benchmarks with this more offshore flow.
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
CT...None.
NY...Freeze Warning from midnight tonight to 8 AM EST Tuesday for
NYZ073-074-179.
NJ...Freeze Warning from midnight tonight to 8 AM EST Tuesday for
NJZ006.
MARINE...Gale Watch from Tuesday evening through late Tuesday night for
ANZ331-332-335-338-340-345-350-353-355.
&&
$$
SYNOPSIS...JC/JM
NEAR TERM...JC/BR
SHORT TERM...JC
LONG TERM...JM
AVIATION...DW
MARINE...JC/JM
HYDROLOGY...JC/JM
TIDES/COASTAL FLOODING...