discussion on 2024-02-21

000
FXUS61 KOKX 211752
AFDOKX

Area Forecast Discussion
National Weather Service New York NY
1252 PM EST Wed Feb 21 2024

.SYNOPSIS...
-- Changed Discussion --High pressure noses in from the northeast this afternoon and
weakens late tonight into tomorrow morning. A frontal system
will move across the area late Thursday night into Friday,
followed by high pressure building in for the start of the
weekend. High pressure then remains in control through the
weekend. A warm front passes through Sunday night, followed by a
weak cold front Monday morning. Another warm front then
approaches from the south during Tuesday.-- End Changed Discussion --

.NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
-- Changed Discussion --For this update once again had to adjust cloud cover up, but not
only through this afternoon, but also through tonight. And the
adjustment up with clouds included northern areas as guidance
previously was not picking up well the shallow layer of higher
RH and clouds. The latest NBM / ConShort is now picking this up
as more obs based data is now getting involved, thus used this
in the hourly database with some slight adjustments. This now
yields mostly cloudy skies for most zones not only for the
remainder of today, but through tonight. This also yields high
temps for tonight by a few degrees. Previous discussion follows.

High pressure situated over the Canadian Maritimes continues to
attempt nose in from northeast to southwest ,and shall remain
in control for this afternoon. Simultaneously, a low pressure
system will pass to our southeast and east far offshore. This is
not enough to bring any impacts to land other than influence
more onshore easterly flow between 5-10 mph, more pronounced for
eastern and southern areas. Visible satellite continues to show
a strat-cumulus layer around 030 kft. This is supported by
latest ceiling obs and OKX sounding from earlier this morning
showing high RH in the vicinity of this layer. The low and
associated onshore flow keeps some cloud cover in place for
southern and eastern parts of the area the afternoon and
evening. High temperatures will be near seasonable, just a touch
below perhaps with upper 30s to lower 40s for daytime maxes.

Look for mostly cloudy skies tonight, with perhaps some
intervals of partly cloudy skies well north with high pressure
slowly losing hold. The cloud cover will reduce the chance for
significant radiational cooling tonight. Lows will be in the
middle 20s to around 30 for most, with the NYC metro area in
the lower to a few middle 30s.-- End Changed Discussion --

.SHORT TERM /6 AM THURSDAY MORNING THROUGH FRIDAY NIGHT/...
As the low well offshore tracks northward to our east, it
pushes the high pressure system out of the Canadian Maritimes
and out into the open North Atlantic. As high pressure loses
control in the region another low pressure system complemented
with a mid-level shortwave approaches from the west.

For the start of Thursday, this low-pressure system is situated
over the Central Plains, tracking east into the Ohio River
Valley. As it approaches, clouds will increase Thursday
afternoon and evening west to east with southerly flow
increasing ahead of the system`s arrival. The increased
southerly flow will allow slightly warmer surface temperatures
on Thursday with highs in the low-40s area-wide.

The southern branch of the jet stream has a zonal structure on
Thursday to our south and west, but dips south in the form of an
upper-level trough on Friday. This puts the mid-Atlantic and
northeast to be in the left exit region of the jet. In response,
the low pressure system will follow this pattern and track
somewhat over the region or directly to the south, most 00Z
models have the center of the system relatively close to the
area on Friday then tracking east and north east of the area on
Friday night into Saturday morning as it exits.

Precipitation will likely start late Thursday night and clear
out Friday night. At the onset, some light snow or rain/snow may
occur in the interior areas. Given onshore flow with warming
temperatures, it won`t last long with very little if any
accumulation. This is looking like mainly a rain even. Event
totals are forecasted to be around a quarter inch over the
course of 36 hours.

Temperatures will be in the 30s as the event starts, but will
warm into the mid/upper-40s mid-event on Friday afternoon. A
cold front will move in as the system exits Friday night
bringing in drier and colder air with lows Friday night in the
low/mid-20s for most. Breezy, northwest winds will follow the
front Friday night and to start the day on Saturday.

.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
High pressure will slowly build in on Saturday as the flow
aloft will be cyclonic. The surface pressure gradient will still
be somewhat tight, so gusty NW winds will make temperatures in
the mid to upper 30s in the afternoon feel about 10 degrees
colder. Winds then subside Saturday night into Sunday morning as
the surface ridge shifts into the region. A return SW flow then
develops for the afternoon, and this will help push high
temperatures back to near normal at 40-45.

A warm front approaches Sunday night. Moisture and lift with
the front may be just enough for some light precipitation, which
would be mainly rain with the exception of a wintry mix at
least at the onset across the northernmost zones. A cold front
then follows Monday morning, ending the threat of precip. Kept
PoPs at slight chance for Sunday night into Monday morning. Dry
otherwise for Monday with highs 50-55. Weak high pressure gives
way to an approaching warm front from the SW on Tuesday. Rain
chances begin in the morning, but become more likely in the
afternoon and night.

.AVIATION /18Z WEDNESDAY THROUGH MONDAY/...
-- Changed Discussion --High pressure remains in place through Thursday morning,
weakening late tonight into Thursday.

VFR to high end MVFR ceilings, with a cloud deck averaging
3000-3500 ft. There may be times when the cloud deck is
scattered, especially early this evening, before becoming broken
to overcast again.

East to southeast winds become light and variable this evening,
and then southerly Thursday morning. Speeds will generally be
10 kt or less.

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

VFR ceilings may briefly scatter out late this afternoon into
this evening. There is a low chance ceilings briefly become MVFR
around 3000 ft into this evening, however, with low confidence
of where and when will not mention in the forecast.

OUTLOOK FOR 18Z THURSDAY THROUGH MONDAY...

Thursday afternoon: VFR, chance of MVFR with showers late.

Thursday night and Friday: MVFR/IFR conds likely develop in
rain, possibly beginning as a wintry mix at the onset at KSWF.

Friday night: Becoming VFR early. NW winds G15-20kt.

Saturday: VFR. NW winds G20-25kt.

Sunday - 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 --Although high pressure is leading to quiet conditions over the
waters right now, a long period southeasterly swell will move
in Wednesday night from strong offshore low pressure. A Small
Craft Advisory is in effect beginning Wednesday night for the
ocean waters, and has been extended in time through the day
Friday. This advisory will likely be extended further in later
updates as the swell sticks around for several days. Wave
heights on the ocean waters will reach 5 to 8 feet later on
Thursday.

SCA conditions continue on the ocean waters through Saturday,
primarily due to swell, but gusts over 25kt are expected into
Saturday behind the passage of low pressure and a cold front. This
will bring advisory conditions to the non-ocean waters as well. Sub-
SCA conditions likely return during Saturday night and last into
most of Sunday as high pressure moves across the area with subsiding
winds and seas.-- End Changed Discussion --

.HYDROLOGY...
-- Changed Discussion --
There are no hydrologic concerns through the middle of next week.-- End Changed Discussion --

.TIDES/COASTAL FLOODING...
-- Changed Discussion --With the approach of a full moon late this week with astronomical
tides increasing, minor coastal flood benchmarks will be approached
for the south shore back bays of Nassau County for the Friday
morning high tide cycle. At this time it appears that other
locations will fall short of minor benchmarks.-- End Changed Discussion --

.OKX WATCHES/WARNINGS/ADVISORIES...
-- Changed Discussion --CT...None.
NY...None.
NJ...None.
MARINE...Small Craft Advisory from 10 PM this evening to 6 PM EST
Friday for ANZ350-353-355.-- End Changed Discussion --

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