okx-afd on 2024-09-19

388
FXUS61 KOKX 190531
AFDOKX

Area Forecast Discussion
National Weather Service New York NY
131 AM EDT Thu Sep 19 2024

.SYNOPSIS...
Low pressure approaches from the south tonight and lingers
offshore through Saturday. High pressure builds in from the
northeast Sunday through Tuesday.

.NEAR TERM /UNTIL 6 AM THIS MORNING/...
Based on radar trends and latest guidance, mainly HRRR, have
further lowered and adjusted the areal extent of rain chances
into late tonight. 18Z NAM12 and latest HRRR really just graze
eastern LI and SE CT.

Otherwise, developing low pressure approaches the region from
the south tonight. As a low level jet ahead of the low center
and enhanced moisture convergence at 850mb push in, expect rain
to move in across eastern LI and SE CT. However, noted trend
above in latest guidance will be watched closely as the area
will be on the NW periphery of the system.

There`s still a chance of some rain for most other locations.
PWATs increase to 1.75-2.00 inches, but convection will be
lacking, however there`s enough mid level forcing to tap into
this moist airmass. Anticipating only the potential of
minor/nuisance flooding which would occur late at night and
would more likely occur over eastern LI or SE CT. See the
hydrology section below for more details.

.SHORT TERM /6 AM THIS MORNING THROUGH FRIDAY NIGHT/...
The coastal low lingers about 50-100 miles south of eastern Long
Island through at least Thursday night as a closed 500mb low
remains nearby. The surface low may then get nudged south and
east Friday night by high pressure attempting to build in from
SE Canada.

Once again, generally higher chances of rain over eastern zones
during Thursday where the deeper moisture and stronger
forcing/convergence remain. Slight chance to chance PoPs for most
other locations. The overall threat for rain then diminishes a
little during Thursday night, but increase back a little on Friday
with a wobble in the low pressure system - bringing back better
moisture and lift. Chances drop off again Friday night as the low
nudges south and east. It will be breezy mainly at the coast during
the short term, with N to NE winds gusting 25-30 mph. Temperatures
through the period are a blend of the previous forecast and 50th
percentile NBM, both of which are cooler than the deterministic
NBM.

.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
**Key Points**

*Improving conditions Saturday into Sunday as high pressure builds
into the region.

*Downward temperature trend to slightly below normal temperatures
expected by early next week.

Global guidance continues to depict the slow moving upper low/trough
situated over New England to start the period. There are varying
degrees of eastward progression on Saturday, though there is
consensus that heights will begin to rise as the low moves east by
Saturday afternoon. Thus, expecting a cloudy, and windy, Saturday
with perhaps some lingering showers though Saturday evening,
especially for eastern Long Island and southeastern CT. Northeast
winds will begin to relax by Sunday afternoon as the low departs and
the pressure gradient weakens.

Thereafter, upper ridging begins to build in with surface high
pressure nosing in from the north. Dry conditions are generally
expected Sunday through Wednesday. A slightly cooler airmass advects
into the area for Monday and Tuesday under easterly flow and highs
in the upper 60s and low 70s. The airmass begins to moderate
somewhat on Wednesday, though still below normal in the low 70.

The NBM with some minor adjustments for Sunday was followed closely
for this update.

.AVIATION /06Z THURSDAY THROUGH MONDAY/...
-- Changed Discussion --Low pressure remains offshore, southeast of Long Island,
through Friday.

VFR. There is a chance of MVFR this morning, with the best
chance at KGON, and possibly into KBDR and KISP, but very low
confidence except for KGON. Likely will not drop to MVFR for NYC
terminals. With a large layer of dry air aloft and a lack of
forcing and lift, will likely be staying dry for the entire TAF
period, so all SHRA chances have been removed from the TAFs.

Higher confidence with the winds. Winds remain NE to N
increasing overnight, especially at the coast terminals, then
winds increase during the day Thursday with gusts 20-25kt.

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

Patchy stratus may develop later this morning leading to
occasional MVFR conditions, but the chances have decreased.
Expecting VFR this morning, but amendments may be needed should
unexpected conditions occur.

OUTLOOK FOR 00Z FRIDAY THROUGH MONDAY...

Saturday: VFR. MVFR east of the NYC terminals possible in
showers, but low chance of occurring. NE gusts around 25kt
possible.

Sunday: VFR. NE gusts 20-25kt possible.

Monday...VFR.

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

.MARINE...
SCA has been extended on all waters through Thursday night and will
likely need to be extended at least on the ocean waters through this
weekend as an offshore low keeps winds and seas elevated. Gusts on
the ocean could reach 30 kt this weekend. For the non-ocean waters,
might need to extend the SCA into Friday, but will probably not be
needed thereafter.

.HYDROLOGY...
Cannot rule out the possibility of minor poor drainage flooding late
tonight into Thursday mainly over eastern LI and SE CT. There is now
fewer guidance suggesting the potential of moderate to heavy
rainfall, so flash flooding is not a concern at this point. Will
still need to watch model trends in rainfall amounts and the track
of the storm as the ingredients for a rainfall heavier than
currently forecast are still present. HREF probabilities of an inch
of rain in an hour are up to 30-40% not too far offshore. Expecting
a total rainfall of up to an inch and a half for these areas through
Friday, however most of this would likely fall late tonight into
Thursday morning. For the rest of the Tri-State area, no impacts
expected with rainfall amounts likely under a half of an inch.

There are no hydrologic issues for Friday through the middle of next
week.

.TIDES/COASTAL FLOODING...
Coastal flood advisories have been expanded to include SW CT
tonight in addition to the one already in effect for southern
Queens and Nassau. A statement remains up for areas adjacent to
NY Harbor. Advisories were then expanded for the Thursday
morning/early afternoon high tide cycle to include locations
adjacent to NY Harbor, western LI Sound, and the south shore
back bays of LI. A statement is in effect for eastern LI and and
New Haven county CT. Advisories will then continue for the
south shore bays and portions of western LI Sound for Thursday
night.

The combination of high astronomical spring tides and deepening
low pressure over the western Atlantic will result in several
rounds of mainly minor coastal flooding over the next couple of
days. Localized moderate coastal flooding is possible for
souther Nassau and SW Suffolk, especially Thursday morning. In
addition, as the low slowly pulls away over the weekend, tidal
piling from a long period easterly swell will continue although
astronomical tides will be gradually coming down. Thus, the
potential is there for continued minor coastal flooding into the
weekend, especially across the south shore bays of western LI
and the SW CT coast.

A high rip current risk continues through Friday for the ocean
beaches due to building E/NE swells and gusty N-NE winds. Seas
on the oceanfront will build to up around 6 ft. However, a high
surf advisory has not been issued as seas are forecast to stay
below criteria of 7 ft. Minor beach erosion is expected, but any
dune issues should be isolated.

.OKX WATCHES/WARNINGS/ADVISORIES...
-- Changed Discussion --CT...Coastal Flood Advisory until 2 AM EDT early this morning for
CTZ009.
Coastal Flood Advisory from 10 AM this morning to 2 PM EDT
this afternoon for CTZ009.
Coastal Flood Advisory from midnight tonight to 3 AM EDT
Friday for CTZ009.
NY...Coastal Flood Advisory until 2 AM EDT early this morning for
NYZ071.
Coastal Flood Advisory from 10 AM this morning to 2 PM EDT
this afternoon for NYZ071-073-078-177.
Coastal Flood Advisory from midnight tonight to 3 AM EDT
Friday for NYZ071.
Coastal Flood Advisory from 8 AM to 11 AM EDT this morning for
NYZ072-074-075.
Coastal Flood Advisory from 8 PM to 11 PM EDT this evening for
NYZ074-075.
High Risk for Rip Currents through Friday evening for NYZ075-080-
081-178-179.
Coastal Flood Advisory from 9 AM this morning to 2 PM EDT this
afternoon for NYZ080.
Coastal Flood Advisory from 8 PM this evening to 2 AM EDT
Friday for NYZ080-178-179.
Coastal Flood Advisory from 8 AM this morning to noon EDT
today for NYZ178-179.
NJ...Coastal Flood Advisory from 8 AM to 11 AM EDT this morning for
NJZ006-106-108.
Coastal Flood Advisory from 8 PM to 11 PM EDT this evening for
NJZ006-106-108.
MARINE...Small Craft Advisory from 6 AM this morning to 6 AM EDT Friday
for ANZ331-332-335-338-340-345.
Small Craft Advisory until 6 AM EDT Friday for ANZ350-353-355.-- End Changed Discussion --

SYNOPSIS...JC/DBR
NEAR TERM...JC/MET/DW
SHORT TERM...JC
LONG TERM...DBR
AVIATION...BR
MARINE...JC/DBR
HYDROLOGY...JC/DBR
TIDES/COASTAL FLOODING...