000
FXUS61 KOKX 011754
AFDOKX
Area Forecast Discussion
National Weather Service New York NY
154 PM EDT Tue Aug 1 2023
.SYNOPSIS...
High pressure builds in from the west this afternoon, becomes
centered over the area on Wednesday and then shifts offshore
Wednesday evening. A warm front pushes through late Thursday
night, followed by a cold front Friday night into early
Saturday. High pressure returns late Saturday through early
Monday. A frontal system then approaches and may push through
the area on Monday.
&&
.NEAR TERM /THROUGH TONIGHT/...
Minor adjustments were made to the forecast based on latest obs
and trends.
A full latitude trough along the east coast will gradually
translate east this afternoon, while high pressure builds in
from the Great Lakes.
It will be another dry day with below normal temperatures.
Dewpoints will drop to the upper 40s and highs will be in the
upper 70s to low 80s. This will give min RH values this
afternoon between 30 and 40 percent. With daytime heating and
cyclonic flow aloft, scattered to broken stratocu is likely
again.
Great radiational cooling conditions are expected tonight. Blended
in the MOS guidance to lower temperatures in the normal cool spots.
The interior and Long Island Pine Barrens should see lows in the
upper 40s to low 50s.
&&
.SHORT TERM /WEDNESDAY THROUGH THURSDAY/...
High pressure becomes centered over the area on Wednesday as
shortwave ridging takes place aloft. Conditions will be similar
to Tuesday, with more sunshine and one final day of low humidity.
The high shifts offshore Wednesday night and a return flow sets
up. Wednesday night will be cool, but warmer than Tuesday night
due to a light S/SW flow and mid to upper level clouds moving
in with an approaching frontal system. This frontal system will
bring the next chance of rain to the area. The first half of
Thursday will likely be dry, but by the afternoon PoPs increase
for the western half of the area.
&&
.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
500mb ensemble means show a weakening upper low across northern
Quebec and attendant trough across the northeast. The trough axis
swings through the local area by 00Z Saturday, with mean upper
ridging building in behind it, from Saturday into early next week.
At the surface, occluding low pressure over southern Quebec brings a
warm front through the area late Thursday into early Friday. The
global ensemble systems (ECE, CMC, GEFS) are a bit divergent in
their handling of this system with respect to timing and magnitude
of precipitation locally for the Friday timeframe. The CMC and
EC have trended on the earlier side with heavier precipitation
overall, while the GEFS members are later and weaker with the
precipitation. Have maintained the chance to slight chance PoPs
from west to east early Friday in association with the warm
front moving through. Cannot rule out some thunder given
elevated instability in BUFKIT soundings late Thursday night as
well.
The area is solidly warm sectored on Friday, as a pre-frontal
trough, followed by a cold front, approach from the west Friday
afternoon and evening. Dewpoints rise into the low 70s under the
southerly flow, and precipitation chances increase by the afternoon.
The airmass looks to destabilize by early afternoon, with a bit of a
cap in place per model soundings, but with 1000-1500 J/kg of
SBCAPE and bulk shear in the 30-40 kt range supportive of
conditional deep moist convection. With PWAT values near 2
inches, heavy rainfall is possible with any storm, though this
looks most probable east of NYC later on Friday afternoon with a
pronounced 850mb jet. NBM probabilities of >1" on Friday are
now up to 30% across much of the area, up from 10% from previous
cycles. WPC maintains a marginal risk of excessive rainfall for
eastern parts of the area on Friday, as a result.
The front looks to move offshore by early Saturday, and surface high
pressure building in through Sunday. Dewpoints drop back into the
upper 50s and low 60s by Sunday, making it feel more comfortable
out. High pressure slides offshore by early Monday, as the next
system approaches from the west.
Temperatures over this period will be near, or slightly below
normal in the low to mid 80s.
&&
.AVIATION /18Z TUESDAY THROUGH SUNDAY/...
-- Changed Discussion --
VFR. High pressure builds over the terminals through tonight and
remains Wednesday.
Light northerly flow continues into this evening, varying at
time from NNW to NNE. Gusts to around 16 kt are possible through
the afternoon. Winds will stay northerly this evening, and
weaken into the overnight, becoming light and variable at
outlying terminals. A northerly flow increases Wednesday
morning.
...NY Metro (KEWR/KLGA/KJFK/KTEB) TAF Uncertainty...
No unscheduled AMD expected. A late day SE-S sea breeze possible
at KJFK.
Sea breezes are likely Wednesday afternoon, after 17Z, with
timing uncertainty.
OUTLOOK FOR 18Z WEDNESDAY THROUGH SUNDAY...
Wednesday afternoon through Wednesday night: VFR.
Thursday: Mainly VFR. Chance of showers and thunderstorms late
day into Thursday night with MVFR.
Friday: Showers and thunderstorms likely with a chance of MVFR,
possibly lower.
Saturday: Chance of MVFR cond in showers, early, then VFR.
Sunday: VFR.
Detailed information, including hourly TAF wind component forecasts,
can be found at: https:/www.weather.gov/zny/n90-- End Changed Discussion --
&&
.MARINE...
With a weak pressure gradient in place due to high pressure
over the area, winds and waves will remain below SCA criteria
through early Friday. Wind gusts over the ocean begin to
increase early Friday and by Friday afternoon, waves increase to
5 ft over the ocean making SCA conditions likely until early
Saturday, when the the pressure gradient weakens with a lighter
wind and 3 to 4 ft seas on the ocean.
&&
.HYDROLOGY...
There are no hydrologic concerns through early Friday.
Heavy rainfall is possible with any thunderstorms on Friday
afternoon and evening, which may result in localized nuisance
flooding across urban and poor drainage areas, particularly east of
NYC. Otherwise, no significant widespread rainfall is expected from
Saturday through early next week.
&&
.TIDES/COASTAL FLOODING...
There is a low risk of rip currents today. There is a moderate risk
of rip currents on Wednesday with 1 ft 11-12s southeasterly
swells.
Astronomical tides continue to increase with the full moon
tonight. Based on several sites achieving minor flooding last
evening and surge values of 0.5 to 0.8ft, have opted to issue an
advisory for the south shore back bays of Queens and Nassau for
tonight. Expecting minor flood benchmarks to be exceeded by only
0.3 or 0.4ft or so during high tide. A statement was issued for
southern Fairfield county, with minor benchmarks expected to
just be reached.
Additional minor flooding is possible during Wednesday evenings
high tide cycles, and statements and/or advisories may be
needed.
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
CT...None.
NY...Coastal Flood Advisory from 6 PM to 9 PM EDT this evening for
NYZ178-179.
NJ...None.
MARINE...None.
&&
$$
SYNOPSIS...DBR/JT
NEAR TERM...JT/DW
SHORT TERM...JT
LONG TERM...DBR
AVIATION...MET
MARINE...DBR/JT
HYDROLOGY...DBR/JT
TIDES/COASTAL FLOODING...