discussion on 2023-08-10

000
FXUS61 KOKX 110010
AFDOKX

Area Forecast Discussion
National Weather Service New York NY
810 PM EDT Thu Aug 10 2023

.SYNOPSIS...
-- Changed Discussion --Weak low pressure passes east of the area tonight. High
pressure follows for Friday, with a frontal system moving across
the area late Saturday into early Sunday. High pressure then
briefly returns again before another storm system moves in late
Monday. High pressure returns for mid- week. A weak cold front
may pass on Wednesday.-- End Changed Discussion --

.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
-- Changed Discussion --Broad, Weak low pressure continues to work its way east this
evening. The latest surface analysis has one of the weak low
centers across central NJ with a warm front draped eastward
along the south shore of Long Island. Mainly stratiform rain has
occurred into the evening with some convective elements
embedded in the system. Area of most concern continues to be
along the southeast coast of the south fork of Long Island.
This is where low level helicity is a bit more enhanced along
the warm front. Surface instability and lapse rates are weak,
which is likely preventing any stronger areas of rotation. A
30-40 kt low level jet has helped pushed the warm front
northward a bit this evening with some coastal observation sites
seeing winds gust to around 35 mph. This activity will quickly
pass east of the area in the next few hours as the weak low
pushes through the region.

Conditions dry out west to east tonight, and the entire region
should be rain free by around 11 pm. Skies begin to clear as
temperatures fall into the 60s overnight.-- End Changed Discussion --

.SHORT TERM /6 AM FRIDAY MORNING THROUGH FRIDAY NIGHT/...
The trough swings east on Friday and heights rise some in response.
At the surface, weak high pressure builds into the area, maintaining
a light W/WNW flow.

Dew points drop into the 50s behind the frontal passage, and coupled
with temperatures in the low to mid 80s, should make for a pleasant
August afternoon under just a bit of daytime cu. Given the
sunshine and downsloping winds, used the NBM 75th percentile for
highs, with low-to-mid 80s once again expected, and perhaps
some upper 80s in the urban metro.

With the light winds and relatively clear skies, blended in the
MAV/MET guidance for lows Friday night, with some parts of the
lower Hudson Valley and the LI Pine Barrens likely falling into
the 50s toward daybreak Saturday. Except for what is already
noted, primarily followed the superblend of guidance for this
update.

.LONG TERM /SATURDAY THROUGH THURSDAY/...
A weak trough with rising heights remains in influence Saturday
morning with surface high pressure nearby. This changes as troughing
develops out ahead of an approaching cold front Saturday afternoon.
Ahead of the front, south and west winds will bring up dewpoints with
the front providing a good source of lift for showers and
thunderstorms. Coverage is expected to be scattered in the afternoon
will a increase in coverage at night as the front passes due to
enhanced forcing along the front. SPC currently has a marginal risk
of severe weather for our area. Model guidance still varies on the
available instability for thunderstorms. The 12Z NAM has SBCAPE as
high as 2000-3000 J/kg while the GFS sits between 1000-1500 J/kg
with only a few small spots of 2000 J/kg. The 6Z ECMWF sits
somewhere in between the GFS and NAM guidance. Its possible a stray
storm or two could produce wind gusts near 60 mph, with most storms
expected to remain sub-severe at this time, but this is subject to
change as more convective-allowing guidance becomes available.

Sunday a northwest wind sets up with drying conditions behind the
cold front. SUnnier skies should allow temperatures to warm into the
mid-upper 80s, with even a few near 90 forecasted in NE NJ and in
the NYC metro.

Monday should start off dry with south winds quickly leading to
rising dewpoints ahead of an overnight cold front. 12 GFS is
currently putting out PWATs of 2.25-2.5". The 90% percentile from
SPC`s sounding climatology page is 1.75" with the max moving average
around 2.15". This, along with sufficient forcing along a cold front
could lead to locally moderate to heavy downpours, at times. WPC
currently has the region under a marginal risk for excessive
rainfall. Its still a good ways away, but worth watching to see if
the signals for heavy rain trend heavier or weaker. The good news is
the system looks to be quite progressive, which hopefully means we
shouldn`t see any slow moving showers. The signal for thunderstorms
doesn`t look as great as Saturday, but could still see isolated to
scattered thunderstorms with some of the strongest areas of forcing.

After the front clears Tuesday morning, clouds should clear allowing
for sunny skies to return for Tuesday afternoon before a weak front
impacts us on Wednesday. Some showers and thunderstorms are possible
with the FROPA, but not looking significant at this time.

.AVIATION /00Z FRIDAY THROUGH TUESDAY/...
-- Changed Discussion --Low pressure passes to the east of the city terminals this evening,
and the eastern most terminals towards midnight.

IFR and MVFR conditions until 2 to 3z at most terminals, otherwise
going VFR quickly from west to east. Sub VFR conditions for a short
time, which includes IFR at KGON until 4-6z. Also TEMPO thunder for
KGON until 3z. Afterwards, VFR prevails for the remainder of the TAF
period.

The wind shifts to the W by 3Z as the low exits east of the city
terminals, and further east by 4-6z. Thereafter, a W to WNW flow
sets up through the early afternoon on Fri. Afterwards a thermal
trough sets up Fri afternoon in which a sea breeze appears likely
for southern coastal terminals with more uncertainty in occurrence
for the remaining terminals. This will likely affect the wind
direction late in the day and early evening.

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

Amendments possible through the remainder of this evening with
improving conditions. And also for wind direction changes with
low confidence in timing Fri aft and eve.

OUTLOOK FOR 0Z SATURDAY THROUGH MONDAY...

Friday night: VFR.

Saturday-Sunday: Mainly VFR. Chance of showers, possibly
thunderstorms, late Saturday into early Sunday morning. VFR for
Sunday afternoon.

Monday: VFR early, then a chance of MVFR with a chance of showers
and thunderstorms.

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

.MARINE...
-- Changed Discussion --South/southwest winds may produce a few isolated gusts around 25 kt
into this evening before subsiding behind the passage of low
pressure.

Otherwise, sub-SCA conds expected on all waters through Monday
afternoon. Monday night wind gusts over ocean waters could
approach 25 kts.-- End Changed Discussion --

.HYDROLOGY...
-- Changed Discussion --No hydrologic concerns are anticipated into the weekend.

Late Monday into Tuesday, brief periods of moderate to heavy
rainfall could occur ahead of a cold front leading to isolated
flooding concerns. After Monday morning, no hydrologic impacts
are expected for the rest of the forecast period.-- End Changed Discussion --

.TIDES/COASTAL FLOODING...
There is a moderate risk for rip currents on ocean beaches Friday
and Saturday.

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

$$
SYNOPSIS...DR
NEAR TERM...DR/DS
SHORT TERM...DR
LONG TERM...BR
AVIATION...JE
MARINE...BR/DR
HYDROLOGY...BR/DR
TIDES/COASTAL FLOODING...