000
FXUS61 KOKX 131746 CCA
AFDOKX

Area Forecast Discussion...CORRECTED
National Weather Service New York NY
146 PM EDT Wed Sep 13 2023

.SYNOPSIS...
A cold front and wave of low pressure along it approach today,
moving through tonight. High pressure then builds in on Thursday,
remaining centered to the west through Friday, before weakening over
the weekend. At the same time, Hurricane Lee is forecast to pass
offshore to our east. A weak frontal system impacts the region
early next week.

Monitor https:/www.weather.gov/okx/tropical or
https:/www.nhc.noaa.gov for the latest NHC forecasts on Hurricane
Lee.

&&

.NEAR TERM /THROUGH TONIGHT/...
-- Changed Discussion --
Made some slight adjustments to POPs, temperatures and
dewpoints to better match with observed trends. No major changes
to the forecast. Highs were adjusted slightly higher but still
mostly expected to range in the mid to upper 70s but some
locations will reach 80 or 81.

A closed low upper trough axis swings east through the Great
Lakes today. The primary surface low tracks into SE Canada as
an attendant cold front and weak surface wave of low pressure
approach the local region. Along and ahead of this, showers and
thunderstorms will move into the area, continuing intermittently
through this evening.

First round of showers and thunderstorms has exited east of Southeast
CT and the Twin Forks of Long Island. The second round of showers
and thunderstorms will be scattered and developing farther west
within the forecast region and is already underway going into mid
afternoon across western parts of the region.

Probabilities for showers and thunderstorms are relatively higher
across the northern half of the forecast region which will be
closer to upper level right rear quad of jet, enhancing vertical
lift. 12Z Morning OKX sounding showed over 2000 J/kg of MUCAPE, so
CAMs may be underestimating the coverage of convection especially
with instability increasing more this afternoon. Still have at
least chance POPs across the region with likely to categorical
POPs for portions of the northern half of the region and Long
Island 18Z this afternoon until 00Z early this evening. Then by
mid to late evening, expect the convection to linger across
Southeast Connecticut and Eastern Long Island. Keeping flood watch
the same without any changes at this time. Will monitor
convection development early this afternoon and see how far west
it develop to determine any potential changes to the flood watch.

The primary threat from this system is the potential for heavy
rainfall leading to flooding. Layer precipitable waters over 1.5
inches and parallel flow evident from low to upper levels may lead
to training of showers and thunderstorms. While typical nuisance
flooding of urban and poor drainage areas is likely, areas of flash
flooding also cannot be ruled out. The wet antecedent conditions
have lowered 1 hr FFG values, with some parts of NE NJ under an
inch. Given this, and the elevated potential to exceed this in
the abundantly moist environment, maintained the region wide
Flood Watch into this evening. See hydro section for additional
details.

While instability is limited, modest speed and directional
shear allowing for increased helicity in the low levels brings
at least the potential of a few strong or severe thunderstorms.
Isolated damaging wind gusts, and even a weak tornado or two,
would be the main hazards. SPC kept a 2% tornado risk outlined
for much of the forecast area.

Forecast highs with the rain and clouds, will only range from
mainly the mid to upper 70s with some locations reaching 80 to
81. Surface features should clear east of Long Island after
midnight, with the region drying out overnight as temperatures
fall into the 50s and 60s.
-- End Changed Discussion --

&&

.SHORT TERM /THURSDAY THROUGH THURSDAY NIGHT/...
Dry conditions return Thursday as a 1022 mb surface high builds into
the Great Lakes on Thursday, setting up a NW flow over the local
region. This advects a much drier air mass into the region, and dew
pts plummet into the lower 50s by the afternoon, a refreshing change
from the recent regime. BUFKIT soundings prog 850mb temps around 9
or 10C, and with a well-mixed BL, afternoon temperatures should
average near or just a hair below normal in the low to mid 70s.
Abundant sunshine prevails.

Clear skies persist Thursday night, and temperatures bottom out in
the 50s for most. Parts of interior CT and the lower Hudson Valley
could fall into the 40s by daybreak, particularly if the flow
lightens enough. Largely followed a superblend of guidance for this
update.

&&

.LONG TERM /FRIDAY THROUGH TUESDAY/...
For Fri, high clouds in advance of Lee will be on the increase,
otherwise temps/dewpoints look similar to those for Thu. Northerly
winds between inland high pressure and Lee will also be on the
increase to 15G25mph as the pressure gradient increases between
inland high pressure and the outer circulation of Lee.

Strongest winds associated with Lee should arrive Fri night and
continue into Sat, with winds backing NW on Sat as the hurricane
passes well east. The hurricane`s wind field will be expanding in
size as it moves northward, and winds especially across coastal SE
CT and eastern Long Island could become strong, sustained 25-30 mph
with gusts up to 40 mph possible. Can`t rule out tropical storm
force winds in those areas right near the shoreline in areas with a
good NW-N exposure.

NBM PoP still clips eastern CT/Long Island on the periphery of Lee,
with only light rainfall amounts expected, at most.

WAA starts early next week, with slight chance for showers and
possibly a thunderstorm Mon/Tue.

&&

.AVIATION /18Z WEDNESDAY THROUGH MONDAY/...
A cold front moves across the terminals this afternoon and
evening. High pressure then builds in tonight through Thursday.

Mainly VFR. There is still a chance for a few showers and
thunderstorms this afternoon and evening, but coverage may be
scattered with higher probabilities across Long Island and
southern Connecticut. Will leave the VCTS for NYC metro
terminals 18-20z for now, with VCTS further east 19-22z.

SW flow to start around 10 kt or less with some coastal terminals S.
Winds will begin to shift to the W and NW late afternoon and early
evening with the cold frontal passage. Wind speeds may weaken after
00z, but gradually increase early Thursday morning as winds
shift towards the NNW-N. This flow continues on Thursday 10-13
kt.

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

Thunderstorms may not occur with just a few showers possible this
afternoon.

Timing of wind shift/cold frontal passage may be off by 1-2 hours.

OUTLOOK FOR 18Z THURSDAY THROUGH MONDAY...

Thursday Afternoon: VFR. Occasional N gust around 15 kt possible

Thursday Night-Friday Night. VFR. N-NNE wind gusts around 20-25
possible, strongest Friday night.

Saturday: VFR. NW wind gusts around 20-25 kt for NYC metro, western
Long Island and western CT. NW gusts 25-35 kt possible eastern Long
Island and southeast CT.

Sunday-Monday: VFR.

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

&&

.MARINE...
Ocean seas with long period swells continue to build. SCA on
the ocean remains through 10Z Fri -- though this will need
further extension.

Non-ocean waters remain below SCA threshold through Thursday.

Ocean seas should continue to build on Thu, reaching 5-8 ft by late
day Thu, 8-12 ft Fri morning, and peaking at 9-14 ft Fri evening.
Seas will then actually start to slowly decrease Fri night into Sat
as strong offshore flow counteracts incoming swell, down to 8-12 ft
by daybreak Sat, 6-8 ft Sat evening, then below 5 ft by Sunday
afternoon.

Sustained N-NW winds or frequent gusts from Lee could peak at
tropical storm force (35 to 40 kt) Fri night into Sat, mainly
on the eastern ocean waters/sound. Elsewhere, SCA conditions
likely from Fri into Sat, with a few gusts up to 35 kt possible
Fri night/Sat AM.

&&

.HYDROLOGY...
Locally heavy downpours are possible in any shower or
thunderstorm into this evening. Rainfall rates could reach 1 to
2 inches per hour in heavier downpours.

This brings the possibility of flooding, especially in low
lying, poor drainage and urban areas. With recent rains, it
will not take much more than an inch in one hour to produce
flash flooding. A Flood Watch is in effect for the entire region
today -- until 6 PM for NE NJ, NYC, the lower Hudson Valley, SW
CT, and western Long Island, and until 2 AM for New Haven,
Middlesex, and New London counties in CT, as well as Suffolk on
Long Island.

Thereafter, no hydrological issues are expected through early next
week.

&&

.TIDES/COASTAL FLOODING...
For Southern Suffolk and Southern Nassau, the high surf advisory
remains in effect until 8PM Saturday. For Brooklyn and Southern
Queens, the high surf advisory remains in effect from 9PM this
evening to 8PM Saturday. The high rip current risk for all ocean
beaches has been extended through Saturday evening.

For Suffolk and Nassau ocean beaches, large breaking waves of 5
to 7 ft will steadily build to 10 to 15 ft in the surf zone by
Friday. For Brooklyn and Queens ocean beaches, large breaking
waves of 5 to 7 ft tonight will steadily build to 6 to 12 ft in
the surf zone by Friday.

Beach flooding and erosion increases Thursday through Saturday.
Scattered areas of dune erosion and localized overwashes are
possible Friday into Saturday.

Any changes to these coastal hazards will be based on the
current fcst track and intensity of Hurricane Lee. Stay tuned to
the latest from the National Hurricane Center regarding the
forecast for Lee.

&&

.OKX WATCHES/WARNINGS/ADVISORIES...
CT...Flood Watch until 6 PM EDT this evening for CTZ005-009.
     Flood Watch through late tonight for CTZ006>008-010>012.
NY...Flood Watch until 6 PM EDT this evening for NYZ067>075-176>179.
     Flood Watch through late tonight for NYZ078>081.
     High Risk for Rip Currents through Saturday evening for NYZ075-080-
     081-178-179.
     High Surf Advisory from 9 PM this evening to 8 PM EDT Saturday
     for NYZ075-178.
     High Surf Advisory until 8 PM EDT Saturday for NYZ080-081-179.
NJ...Flood Watch until 6 PM EDT this evening for NJZ002-004-006-
     103>108.
MARINE...Small Craft Advisory until 6 AM EDT Friday for ANZ350-353-355.

&&

$$

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