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-- Discussion containing changed information from previous version are highlighted. --
000
FXUS61 KOKX 012145
AFDOKX

Area Forecast Discussion
National Weather Service New York NY
545 PM EDT Thu Jun 1 2023

.SYNOPSIS...
High pressure weakens tonight. Back door cold front moves in Friday.
This front moves south of Long Island Friday night. High pressure
will begin to approach from the north Saturday. An area of low
pressure will begin to exit Saturday night with weak high
pressure Sunday into Monday. A cold front is expected Tuesday.
Low pressure lingers in the area Tuesday through Thursday. This
area of low pressure may linger nearby through the middle of
next week.

&&

.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
Mostly clear sky conditions expected tonight for all locations
except Long Island and Southeast Connecticut. This will be where
some lower level clouds will move in. There will be potential
for fog along the coast as well. Onshore flow will be light
along the coast, with otherwise very light to calm winds.

Models overestimated the amount of low moisture and low clouds
and fog previous night and even into today. Kept the mention of
fog to patchy coverage.

Used a blend of NBM, MAV, MET and CONSRaw for forecast lows,
mid 50s to mid 60s range.

&&

.SHORT TERM /6 AM FRIDAY MORNING THROUGH SATURDAY/...
Light winds initially Friday with mostly sunny conditions to
start. Any morning fog and low clouds along the coast are
expected to burn off with diurnal heating.

Ahead of an approaching back door cold front, a pre-frontal
trough develops and moves in for the afternoon. Clouds and
eventually some showers and thunderstorms develop in the
afternoon.

Temperatures about the same as previous day at 850mb, about
16-17 degrees C. However the vertical mixing is shown to be
deeper, allowing for more adiabatic warming. Also, dewpoints
trend several degrees higher. This will allow for more low level
CAPE.

The sea breeze will keep coastal locations cooler compared to
farther inland. Coastal locations have forecast high
temperatures in the mid 70s to near 80 while NYC will be more in
the mid to upper 80s. Interior areas forecast to have high
temperatures more in the mid 80s to near 90.

As the back door cold front approaches from the north, showers
and thunderstorms pop up and develop in the afternoon from north
to south. This will be from the increased low level instability
and convergence along the pre-frontal trough.

The showers become more likely going into Friday night along
with a continued chance of thunderstorms as the back door cold
front itself moves in from the north. Higher chances will be
across Southern Connecticut and Long Island compared to farther
west.

Bulk shear 0-6 km limited by models to near 20 kt, but elevated
instability remains into the night. Also, with mid level height
falls, could have some small hail with some thunderstorms.
Expecting most convective activity to stay sub-severe.

The back door cold front moves across Friday night and will be
south of Long Island on Saturday. Winds become NE late Friday
night and increase on Saturday, becoming gusty. A more stable
airmass develops in the area, allowing for thunderstorm chances
to decrease with showers lingering around going into early
Saturday.

The weather becomes drier Saturday afternoon with high pressure
building down from Southeast Canada. Temperatures are expected
to be below normal with highs mostly in the 60s.

&&

.LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/...
-- Changed Discussion --
Minor adjustments made to temperatures and dewpoints in just a
few spots to account for latest trend in observations.
Otherwise, forecast is on track.

Low pressure to our east begins to push out further east Saturday
night into Sunday with a weak ridge of high pressure nosing in from
the west in between the exiting low and a new low to the north
SUnday in to Monday. Most deterministic models and ensembles
have agreed with this solution for the 6Z and 12Z runs. Have
lowered chances for showers Sunday into Monday to account for
weak conditions for lift and slightly drier air. Did not run
completely with the NBM on this as it had POPs too high for that
period, contradicting recent deterministic and model guidance.
Temperatures will also remain cooler during Sunday to Monday
time frame as heights remain generally low with north winds and
cooler 850 mb temps aloft. Its important to note that while I
refrained from using NBM guidance for temperatures, opting to
use CONSALL instead, a different in-house model consensus, there
is a 20+ degree spread in high temperatures for Sunday and
Monday between NBM`s 10th and 90th percentiles. This means
confidence is not great and is still subject to change given the
track of the first low, which has been changing position from
model run to model run.

A cold front will likely move through Tuesday from a deepening upper-
low dropping south from Canada into New England. This upper-low
will build down to the surface as it continues to retrograde
south and to the west of us. This system is supposed to bring
better rain chances Wednesday and Thursday with general cyclonic
flow over the area and rain chances on Tuesday also along a
cold front.
-- End Changed Discussion --

&&

.AVIATION /22Z THURSDAY THROUGH TUESDAY/...
High pressure remains in control into Friday. A backdoor cold front
approaches during Friday afternoon.

VFR. There is a chance of MVFR to IFR stratus late tonight at KJFK,
however with low confidence only have scattered 010. More likely IFR
at KISP and KGON, and with increased confidence included a TEMPO for
IFR ceilings. Patchy MVFR fog is possible, however, with low
confidence and patchy fog, have not included fog in any of the
terminals.

A light southerly flow continues at the terminals, except for NE to
E winds at KLGA that becomes SE to S late in the afternoon, with
timing uncertain. Winds become light and variable this evening and
overnight. Winds then become southerly Friday morning, with timing
uncertain as light and variable winds may continue longer than
forecast.


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

Timing of the wind shift to SE to S at KLGA uncertain.

There is a chance of MVFR to possibly IFR stratus at KJFK late
tonight into Friday morning, 05Z to 12Z, and with uncertainty at
this time will only have a TEMPO for scattered stratus.


OUTLOOK FOR 18Z FRIDAY THROUGH TUESDAY...

Friday afternoon: Mainly VFR. A chance of showers/thunderstorms,
likely north and east, with MVFR during the afternoon and at night.

Saturday: MVFR to IFR with showers in the morning, becoming a slight
chance during the afternoon with improvement to VFR possible. NE
winds 10-15kt with gusts 20-25kt, highest at the coastal terminals.

Sunday: Mostly VFR, a chance of MVFR with showers east of the NYC
metro terminals. N wind 15-20kt gusts 25-30kt east of the NYC metro
terminals.

Monday: VFR, a slight chance of showers.

Tuesday: VFR, a chance of afternoon and evening showers and
thunderstorms with MVFR.


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

&&

.MARINE...
Sub-SCA conditions forecast until Saturday with weak pressure
gradient in place, then SCA conditions likely for most waters
for Saturday with 5-6 ft seas on the ocean with an increase in
pressure gradient. This will be as high pressure starts to build
in from Southeast Canada.

SCA will be met for ocean waters Saturday night with 25 kt wind
gusts and 5-6 ft waves. Only eastern ocean waters will meet SCA
conditions through Sunday with 25-30 kt wind gusts and 5 ft waves.
SCA may persist into early Monday with 5 ft waves for E ocean
waters, wind gusts will be below 25 kt at that time. Sub-SCA
conditions forecasted for the remainder of the period.

&&

.HYDROLOGY...
No hydrologic impacts expected through early next week.

&&

.TIDES/COASTAL FLOODING...
-- Changed Discussion --
A moderate rip current risk is expected Friday and Saturday.
-- End Changed Discussion --

&&

.OKX WATCHES/WARNINGS/ADVISORIES...
CT...None.
NY...None.
NJ...None.
MARINE...None.

&&

$$
SYNOPSIS...JM/BR
NEAR TERM...JM/BR
SHORT TERM...JM
LONG TERM...BR
AVIATION...MET
MARINE...JM/BR
HYDROLOGY...JM/BR
TIDES/COASTAL FLOODING...