000
FXUS61 KOKX 041755
AFDOKX
Area Forecast Discussion
National Weather Service New York NY
155 PM EDT Fri Aug 4 2023
.SYNOPSIS...
A frontal system approaching today will move across the region
tonight. High pressure returns for the weekend. Another frontal
system is expected to impact the area from late Monday into Tuesday.
High pressure builds in briefly Wednesday, followed by another
late week frontal system.
&&
.NEAR TERM /THROUGH TONIGHT/...
A Severe Thunderstorm Watch is now in effect for Orange and
Putnam Counties until 8 PM this evening.
Storms can be seen firing up ahead of an approaching cold front
on current radar and satellite imagery across northern PA and
through central NY. Although currently below severe criteria,
the storms will continue to move southeast and strengthen. Due
to the timing of the front, our area is on the extreme eastern
end of the severe threat today. Orange and Putnam counties are
the only area currently in the Severe Thunderstorm Watch, but
trends this afternoon will continue to be monitored and the
Watch may be expanded if needed. Latest SPC mesoanalysis
currently has about 1000 J/kg of SBCAPE across the Lower Hudson
Valley, which is expected to increase to close to 2000 J/kg by
later this afternoon and remain uncapped. This combined with
effective bulk shear values of 30-35 kt could allow storms to
produce damaging wind gusts and isolated large hail. The
thinking right now is that any activity will weaken once making
it through northern portions of the Lower Hudson Valley and then
continue below severe criteria.
Ahead of this evening`s storms, weak low level warm air
advection over the area is allowing for the development of
spotty showers, mainly along the coast. There doesn`t appear to
be enough forcing for any shower to become deeply vertical to
allow for lightning generation until later this afternoon when
instability increases as the temperatures rise a bit.
WPC also places the area in a generic marginal risk for
excessive rainfall. PWATs of near 1.5 inches may result in heavy
rainfall in any thunderstorm, which may result in localized
urban and small stream flooding.
The cold front moves through tonight and the chance of showers
and thunderstorms continues to decrease into the early morning
on Saturday.
&&
.SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
Behind the frontal passage, high pressure builds into the region
for the weekend result in generally clear skies and dry
conditions with temperatures moderating a bit. Highs will be in
the low to middle 80s for much of the region. High pressure
shifts over the area and offshore Sunday night giving way to
the next frontal system expected to approach the area on Monday.
&&
.LONG TERM /MONDAY THROUGH THURSDAY/...
Changes have been relatively minor in the extended period.
A shortwave trough over the Northern Plains over the weekend will
work east across the norther tier of the country. There are some
timing issues with the global models as the feature interacts with a
northern branch shortwave trough dropping southeast across central
Canada and into the Great Lakes. This will likely result in some
timing issues. In the meantime, consensus supports a frontal system
approaching Monday and moving through the area Monday night into
Tuesday. This will result in increasing chances for showers and
thunderstorms Monday afternoon into Monday night. The associated
surface low occludes to northwest of the area with the area in close
proximity to the triple point. Whether or not we can warm sector is
uncertain at this stage, but will determine how much we can
destabilize. Timing of the frontal system moving across the area
will also be an issue which looks to be at night. Right now the
severe weather threat looks to be low. In addition, the system also
looks to be progressive enough to limit the flood threat.
High pressure builds in late Tuesday into Wednesday, then offshore
Thursday with a return southerly flow. A late week frontal system
may be in the offing.
Temperatures will remain near seasonable levels through Thursday,
with moderate humidity with dew points mainly in the 60s, slightly
higher Monday ahead of the cold front.
&&
.AVIATION /18Z FRIDAY THROUGH WEDNESDAY/...
-- Changed Discussion --
An approaching cold front will move across tonight.
Bkn line of tstms over the southern tier of central NY and N PA
will sink SE toward the area into this evening, with likely
late day impact at KSWF. Impact at most other terminals doubtful
and timing uncertain as activity should weaken after dark.
Delayed possible TEMPO impact at the NYC metros until 01Z-04Z,
and an hour or two later farther east.
S-SW winds this afternoon are mostly lighter than previous
expectations due to cloud cover and have shaded lower, with
speeds 10-15 kt and an ocnl gust to 20 kt. At the NYC metros,
highest sustained winds at KJFK with an ocean sea breeze, and
most frequent gusts at KLGA.
Winds veer more to the SW and diminish this evening, then shift
light NW late tonight with cold fropa and veer N after 12Z-13Z.
...NY Metro (KEWR/KLGA/KJFK/KTEB) TAF Uncertainty...
Low confidence on thunder chances and timing this evening as
storms will be weakening on approach.
OUTLOOK FOR 18Z SATURDAY THROUGH MONDAY...
Saturday afternoon through Sunday: VFR.
Monday through Tuesday: Chance of showers and thunderstorms,
from NYC north/west late day Mon, then throughout Mon night and
Tue. MVFR or lower cond possible.
Tuesday night and Wednesday: VFR.
Detailed information, including hourly TAF wind component
forecasts, can be found at: https:/www.weather.gov/zny/n90-- End Changed Discussion --
&&
.MARINE...
Winds increase and seas build this afternoon and evening ahead
of a cold front. Winds should largely stay below 25 kt, but an
occasional gust to 25 kt cannot be ruled out. Ocean seas should
also build to 4 ft, but should stay below 5 ft. Winds and seas
subside behind the cold front passage late tonight into
Saturday morning.
Winds and seas will remain below SCA levels across the forecast
waters from Saturday morning through Monday evening. With an
increasing southerly flow ahead of a frontal system Monday ocean
seas will likely build to SCA levels by late Monday night and
remain elevated into Tuesday morning. Occasional gusts on the
ocean waters may also be near SCA levels during the same time
period.
&&
.HYDROLOGY...
Showers and thunderstorms from late day well NW of NYC, into
this evening elsewhere, may produce locally heavy rainfall.
Minor nuisance poor drainage flooding is in the main threat.
There are no hydrologic concerns from Saturday through the middle
of next week.
&&
.TIDES/COASTAL FLOODING...
There is a moderate risk of rip current development at the
ocean today and Saturday with a 2-ft 9-10 s period S swell.
The threat of minor coastal flooding has ended. A statement may
be possible for the south shore back bays for tonight`s high
tide cycle, but water levels will continue to lower.
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
CT...None.
NY...None.
NJ...None.
MARINE...None.
&&
$$
SYNOPSIS...DW/MW
NEAR TERM...JT/MW
SHORT TERM...MW
LONG TERM...DW
AVIATION...BG
MARINE...DW/MW
HYDROLOGY...DW/MW
TIDES/COASTAL FLOODING...