discussion on 2023-08-02

000
FXUS61 KOKX 021408 CCA
AFDOKX

Area Forecast Discussion...CORRECTED
National Weather Service New York NY
1008 AM EDT Wed Aug 2 2023

.SYNOPSIS...
High pressure over the region on Wednesday shifts offshore by
Wednesday evening. A warm front then approaches from the west on
Thursday. The warm front pushes through late Thursday night into
Friday morning, followed by a cold front late Friday into Friday
night. High pressure returns for the weekend. Another frontal
system then expected to impact the area Monday into Tuesday, with
high pressure returning for the middle of next week.

.NEAR TERM /THROUGH TONIGHT/...
The forecast is on track with some minor updates to account for
recent observations. The previous discussion follows.

Upper trough axis heads offshore today as the flow becomes more
zonal, or even some weak upper ridging as heights rise somewhat
during the day. At the surface, 1023mb high pressure centered
over New England slowly drifts to the east and offshore by this
evening. This will keep the area dry today and tonight with just
a few mid/high level clouds overhead under the large scale
subsidence. Northerly flow becomes southerly by afternoon as the
high moves east.

One last comfortable day with dewpoints in the upper 40s and low
50s, and highs in the upper 70s and low 80s. Southerly flow will
keep low temperatures Wednesday night a few degrees warmer than the
previous night.

.SHORT TERM /THURSDAY THROUGH THURSDAY NIGHT/...
-- Changed Discussion --The aforementioned high pressure continues to shift offshore on
Thursday as deep southwesterly flow continues to bring moisture
into the area at the surface and aloft. A mid level trough begins
to approach the northeast from the Great Lakes later on Thursday
as an upper jet dives down through the OH Valley. Surface low
pressure then develops across southern Quebec, and brings a warm
front close to the area by Thursday night. So while most of the
day on Thursday will be dry, cloud cover will increase from west
to east, and shower/tstm chances increase by Thursday afternoon
with the front approach, especially north and west of NYC. Have
opted to add chance/slight chance thunder to the forecast given
marginal instability shown in BUFKIT NAM and GFS soundings,
starting late Thursday afternoon. Shower chances then extend to
the entire forecast area by Thursday night, though expect the
thunderstorm threat to decrease after 00Z. Light rain chances
continue into the overnight on Thursday, with the warm front in
the vicinity.

A seasonable low to mid 80s for high temperatures on Thursday.-- End Changed Discussion --

.LONG TERM /FRIDAY THROUGH TUESDAY/...
Not much change in the long term and stuck fairly close to the
NBM/latest forecast.

A warm front continues to lift north of the CWA early Friday
morning. An increasing southerly flow is expected on Friday, which
should help usher in a more moist and humid airmass into the area.
The combination of the cold front approaching as well as a decent
upper level shortwave, expect showers and thunderstorms on Friday.
POPs to gradually increase through the day, with the best chances for
POPS in the afternoon and early evening. One question that still
needs to be answered for Friday, is how much sun can break through
before the arrival of the cold front. If enough surface based
instability can get involved then some of the storms could have the
potential to become severe later Fri and Fri evening. In addition to
the potential for severe weather, PWATS increase to 1.5-1.75 inches,
so any storms will be capable of producing brief heavy downpours.

The cold front moves through Friday night bringing an end to any
precipitation and the winds switch to a drier NW direction. This
will set the stage for lower humidity and dry conditions into the
weekend.

Another system approaches on Monday. Continued with a consensus
approach (NBM/official forecast) for late in the period, especially
with regards to PoPs into Monday. There is the potential for
thunderstorms and possible severe weather if certain ingredients
come together later Monday. Will continue with chance pops on
Tuesday, but drier weather returns for Wednesday. Temperatures
through the period will be for the most part right around
normal.

.AVIATION /12Z WEDNESDAY THROUGH SUNDAY/...
VFR as high pressure builds over the terminals today. The high
slides offshore tonight.

A light NNW to NNE flow less than 10 kt should prevail
today. Coastal sea breeze development is expected late
morning/early afternoon. Timing of seabreeze at KGON which could
go southerly a couple hrs earlier than forecast.

Tonight, the winds become light, but take on more of a southerly
flow with the high building offshore.

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

Timing of seabreeze may be off by an hour.

OUTLOOK FOR 12Z THURSDAY THROUGH SUNDAY...

Thursday: Mainly VFR. Slight chance of afternoon showers mainly
NW of the NYC metros.

Thursday night: Chance of showers and possibly a thunderstorm,
with MVFR conditions possible.

Friday: Showers/tstms likely. MVFR conditions likely, IFR
possible.

Saturday: VFR.

Sunday: VFR.

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

.MARINE...
Sub SCA conditions are likely until Thursday afternoon into the
evening with high pressure overhead. As the high shifts
offshore, southerly flow picks up and gusts on the ocean start
to get to 20 kt, with ocean seas closer to 4 ft by Thursday
night.

SCA conditions will be possible, especially on the ocean waters as
seas increase to 4-5 ft and wind gusts approach 25kt on Friday. It
is possible that SCA conditions may be needed on the non-ocean
waters, mainly for wind gusts. A cold front is expected to move
through Friday night resulting in a wind shift to the NW. Seas will
come down late Friday night into early Sat AM. The pressure gradient
relaxes Saturday with building high pressure and a lighter wind
resulting in 3 to 4 seas on the ocean.

.HYDROLOGY...
No hydrologic concerns through the weekend. There is some potential for
heavy rain in association with any thunderstorms early next
week towards Monday, but there remains a lot of uncertainty this
far out in time.

.TIDES/COASTAL FLOODING...
There is a low risk of rip currents Wednesday. There remains a
moderate risk of rip currents on Thursday with 2-3 ft 11-12s
southeasterly swells, approaching 3-4 ft late and towards
evening.

Astronomical tides remain high with the full moon from Tuesday
evening. Based on several sites achieving minor flooding last
evening and surge values of 0.5 to 0.8ft in the model guidance,
have opted to issue again an advisory for the south shore back
bays of Queens and Nassau for tonight with coastal flood
statements for Brooklyn and Staten Island. Expecting minor flood
benchmarks to be exceeded by several tenths during high tide
this evening. A statement was also issued for southern Fairfield
county, with minor benchmarks at Stamford and Bridgeport
expected to just be reached for another evening.

Minor flooding is again possible during Thursday evenings high
tide cycles, and additional statements and/or advisories may be
needed.

.OKX WATCHES/WARNINGS/ADVISORIES...
CT...None.
NY...Coastal Flood Advisory from 8 PM this evening to midnight EDT
tonight for NYZ178-179.
NJ...None.
MARINE...None.

SYNOPSIS...BC/DBR
NEAR TERM...BC/DBR
SHORT TERM...DBR
LONG TERM...BC/DBR
AVIATION...BC
MARINE...BC/DBR
HYDROLOGY...BC/DBR
TIDES/COASTAL FLOODING...