000
FXUS61 KOKX 141122
AFDOKX
Area Forecast Discussion
National Weather Service New York NY
722 AM EDT Mon Aug 14 2023
.SYNOPSIS...
High pressure over the region weakens today as a frontal system
approaches from the southwest. The frontal system will impact
the region tonight through Tuesday evening. High pressure
returns for Wednesday and Thursday. A cold front approaches
Thursday night and passes through on Friday. High pressure
returns for the weekend.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
Update was for current conditions.
For today a nearly zonal flow, with weak upper riding will move
across the northeast today as trough moves into the Great Lakes
region and upper midwest. At the surface high pressure over the
region weakens as a low slowly deepens south of the Great
Lakes. Most of the day will be dry, with increasing clouds as a
warm front approaches. Showers may begin to move into central
New Jersey late in the day.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH WEDNESDAY/...
The warm front approaches this evening with the main low moving
into the eastern Great Lakes. A secondary low is likely to
develop this evening across eastern Pennsylvania on the warm
front and as system begins to occlude. The warm front and low
move through the region this evening and overnight. Strong
frontal forcing, with precipitable water values increasing to 2
to 2.5 inches, about as high as values go locally per SPC
sounding climatology, along with weak CAPE and instability, will
lead to showers and thunderstorms, some of which could produce
heavy rainfall, especially late tonight. With recent rainfall,
Saturday night, wet antecedent conditions, and the heavy
rainfall could lead to scattered areas of flash flooding. Much
of the region is in a slight risk for excessive rainfall. There
is some uncertainty where the heaviest rainfall will occur, and
will be dependent on the development of the secondary low and
placement of the warm front as the low deepens. Currently the
highest rainfall is expected from the New York City metropolitan
area and eastward along the coast.
In addition there is a chance of strong to severe thunderstorms
late tonight, and northeastern New Jersey into the lower Hudson
Valley and eastward across Long Island are in a marginal risk
for severe weather with the primary threat being damaging wind
gusts. And with increasing helicity along the warm front a
brief tornado cannot be ruled out.
There will be a lull in the rainfall and severe weather threat
later Tuesday morning, however, with the approach of a cold as
the low tracks across the region, another round of moderate to
heavy rainfall and strong to severe storms will be possible. And
the entire region is in a marginal risk for severe strong
Tuesday.
The cold front moves through late Tuesday evening, and drier
air begins to advect into the region behind it as high pressure
returns.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
Relatively flat flow aloft with weak surface high pressure
Wednesday night into Thursday morning before a 500mb trough axis
shifting through the Great Lakes causes the flow aloft to
become more cyclonic by late Thursday. The trough aloft begins
to lift into the Northeast, sending a cold front across the area
during Friday. Dry through at least Thursday afternoon, with
chances of showers and thunderstorms beginning at night on
Thursday and continuing through the daytime hours of Friday.
Deep-layered ridging on Saturday will provide dry weather for
the upcoming weekend as high pressure takes control.
NBM looked good for temperatures through the long term - near
normal through Saturday, then warmer on Sunday with heights
rising.
&&
.AVIATION /11Z MONDAY THROUGH FRIDAY/...
-- Changed Discussion --
High pressure will be in control today. A warm front and low
pressure approach late tonight into Tuesday.
VFR conditions through at least 00-03z this evening. Chances of
MVFR or lower in showers will be possible roughly 03-06z, then
IFR and moderate to heavy showers anticipated after around 06z
with a chance of a thunderstorm. LLWS will be possible as well,
however not enough confidence yet to include LLWS in the TAFs
just yet.
A sw flow under 10 kt develops after the morning push, then
becomes S-SE around 10 kt in the afternoon. The flow backs SE-E
tonight ahead of an approaching warm front/weak low center.
...NY Metro (KEWR/KLGA/KJFK/KTEB) TAF Uncertainty...
Timing of the winds turning S-SE, then SE-E may be off by an
hour or two. Onset of MVFR/IFR/SHRA tonight may be off by a few
hours.
The afternoon KJFK haze potential forecast is YELLOW...which implies
slant range visibility 4-6SM outside of cloud.
OUTLOOK FOR 12Z TUESDAY THROUGH FRIDAY...
Tuesday: IFR improves to MVFR in the morning, then mainly VFR
in the afternoon.
Tuesday night: Chance of showers and thunderstorms, mainly in the
evening, especially east of NYC terminals. MVFR or lower possible at
times.
Wednesday through Thursday: VFR. Chance of showers and thunderstorms
Thursday night with MVFR or lower possible at times.
Friday: MVFR or lower possible at times with a chance of showers and
thunderstorms. W gusts near 20 kt.
Detailed information, including hourly TAF wind component forecasts,
can be found at: https:/www.weather.gov/zny/n90-- End Changed Discussion --
&&
.MARINE...
No changes to the winds and seas at this time as weak high
pressure remains over the waters.
Winds and seas remain below SCA levels across the forecast
waters today through Thursday. Winds will remain below SCA
criteria, for late Thursday night into Friday, but waves may
reach 5 feet on ocean waters as SW to W winds increase ahead of
a cold front.
&&
.HYDROLOGY...
Rainfall of 1.25 to nearly 2 inches is possible tonight through
Tuesday evening, with locally higher amounts possible.
The heaviest rainfall is expected later this evening into late
tonight, with higher rainfall totals likely along the coast. The
heavy rainfall along with wet antecedent conditions from
rainfall Saturday night, may lead to scattered areas of flash
flooding.
From Wednesday through the end of the week, no hydrologic impacts
are expected.
&&
.TIDES/COASTAL FLOODING...
For today there is a low risk for the development of rip
currents at the ocean beaches of NYC, Nassau county, and
southwestern Suffolk county, with a moderate risk at the
southeastern Suffolk ocean beaches.
Tuesday a moderate risk for the development of rip currents is
expected at all the ocean beaches.
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
CT...None.
NY...None.
NJ...None.
MARINE...None.
&&
$$
SYNOPSIS...JC/MET
NEAR TERM...MET
SHORT TERM...MET
LONG TERM...JC
AVIATION...JC
MARINE...JC/MET
HYDROLOGY...JC/MET
TIDES/COASTAL FLOODING...