discussion on 2024-01-06

000
FXUS61 KOKX 061438
AFDOKX

Area Forecast Discussion
National Weather Service New York NY
938 AM EST Sat Jan 6 2024

.SYNOPSIS...
Low pressure will pass south of Long Island tonight, and east of the
region on Sunday. High pressure then builds in for Monday. Low
pressure strengthens and passes west of the region Tuesday into
Wednesday. The low will then move northeast and weaken Wednesday
into Thursday. Weak high pressure then returns thereafter
through Friday.

.NEAR TERM /THROUGH SUNDAY/...
-- Changed Discussion --The forecast remains mainly on track this morning. Hourly
temperatures and dewpoints for the remainder of this morning
have been adjusted toward the latest trends. The models have
clustered around a track, with the low progged to pass about 100
mi or less S of LI tngt, then slip inside the benchmark and
pass E of Cape Cod on Sun. Based on this latest information,
snowfall amounts have been reduced slightly across the board.
The nly track could introduce some mixing inland, and the speed
of the sys may serve to be a limiting factor as well. At the
coasts, unless something drastic changes, ely flow should keep
the llvls mild and reduce the snowfall potential.

The watch across sern CT has been replaced with an advy. Otherwise,
there were no changes made to the winter weather headlines.

The close track introduces wind advy potential for the ern third of
the cwa, especially the Twin Forks. However, the modeling keeps the
low mainly in the 990s until it gets close to Nantucket Sun mrng.
Based on this, did not enhance the model data with this fcst,
with the official numbers close to but blw advy lvls.

The models continue to signal some areas of snow on the backside of
the low on Sun. Some minor additional accums of mainly around an
inch or less were maintained in the fcst. Limiting factors will
be rates, and near the coast, the relatively mild bl. That
said, brought temps close to the 4km NAM Nest numbers tngt and
Sun, which is colder than the MOS and NBM.-- End Changed Discussion --

.SHORT TERM /SUNDAY NIGHT THROUGH MONDAY NIGHT/...
The snow is expected to be offshore by 00Z Mon, with clearing skies
due to subsidence and a dry airmass building in. Gusty NW flow as
the low pulls away, especially LI surrounded by the warm water.
Across the interior, fresh snowpack could allow for decoupling and
possibly temps blw the NBM fcst.

A low 1030s high builds towards the area on Mon, and over the area
on Mon ngt. This will produce dry and mostly sunny wx on Mon, and
cold temps Mon ngt with the high ridging across the cwa. The
only thing which might hold temps back from completely bottoming
out across the interior will be some increasing high clouds
ahead of the next sys. Stuck with the NBM.

.LONG TERM /TUESDAY THROUGH FRIDAY/...
*Key points*

* Another potentially significant storm system passing west of the
region Tuesday into Wednesday. Heavy rain, flooding, strong winds,
and coastal flooding will all be possible.

* Strong wind possibility with potential for gusts of 45 to 60
mph, highest along the coast Tuesday night.

Deepening trough with strengthening upper level jet picks up Gulf
moisture Tuesday. The upper jets left front quadrant approaches
Tuesday night, getting near the region by early Wednesday.

Mid level trough moves across Wednesday with its associated
vorticity maximum. Another shortwave potentially moves near for
Thursday with otherwise quasi-zonal flow Wednesday through Friday.

At the surface, low pressure deepens as it travels from South
Central US to the Great Lakes Tuesday into Wednesday. The
strengthening baroclinic zone will increase frontogenesis and
enhanced lift can be expected across the region. With layer
precipitable waters approaching near 1.25 inches Tuesday night,
heavy rain can be expected at times.

Bulk of rain finishes by early Wednesday morning, but more rain,
more shower-like with periodic timing is forecast for the rest of
Wednesday. Dry conditions are forecast Wednesday night through
Friday morning. Next rain in the forecast does not arrive until late
Friday.

Forecast overall trended a few degrees warmer on Tuesday with
some higher POPs both for Wednesday as well as Friday into
Friday night compared to the previous forecast.

.AVIATION /15Z SATURDAY THROUGH WEDNESDAY/...
-- Changed Discussion --Low pressure approaches from the south today, passing east of Long
Island tonight into Sunday.

VFR through this morning. Precipitation develops in the late
afternoon from west to east, snow initially, but mixing with and
eventually changing to rain along the coast with inland staying
snow for this afternoon into tonight.

Conditions deteriorate late afternoon after the onset of snow
inland and a rain/snow mix towards the coast. MVFR to IFR
conditions can be expected. The mix of rain and snow along the
coast transitions tonight to plain rain. KHPN more in between so
they will just transition from pure snow to a mix of rain and
snow with KSWF remaining all snow.

For tonight into early Sunday, mainly IFR to locally LIFR conditions
are expected. A lull in precipitation is forecast overnight before a
mix of rain and snow showers develops Sunday along the coast with
additional snow showers inland.

Light winds become E-ENE late this morning and increase this
afternoon to near 10-15 kt. E-ENE winds increase to near 20 kt
along the coast tonight before lowering to near 10-15 kt range
overnight into early Sunday. Gusts near 25-30 kt are forecast
late this afternoon through the evening with gusts more in the
20-25 kt range overnight and then closer to 20 kt for Sunday.

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

Amendments likely this afternoon and tonight with timing of
categorical changes and the timing of the precipitation changes.

OUTLOOK FOR 12Z SUNDAY THROUGH WEDNESDAY...

Sunday: IFR or lower with snow inland and rain/snow near the coast.
NYC metro and coast may end as snow in the afternoon. Becoming VFR
at night. NW winds becoming N 10-15kt, gusting near 20 kt,
diminishing during the afternoon.

Monday: VFR.

Tuesday: VFR early becoming MVFR or lower. Rain during the
afternoon. E winds 15-20kt with gusts 25-30kt in the afternoon. SE
winds increasing Tuesday night to 25-35kt, gusting 40-45kt, highest
winds along the coast. LLWS likely at night.

Wednesday: MVFR or lower with rain in the morning. Rain ending late
in the day with conditions improving. S-SW wind 20-25kt gusting 35-
45kt. Gusts decrease afternoon into the night.

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

.MARINE...
Gales develop tngt, then winds diminish from W to E on Sun as the
low pulls away. The gale warning was extended until noon for the
ern waters. A SCA will be needed elsewhere. SCA seas then last on
the ocean thru the day on Mon. On the protected waters, winds blw
SCA lvls Sun ngt thru Mon as high pres builds in.

SCA level seas on the ocean appear likely Tuesday through Wednesday
night. For non-ocean waters, parts of LI Sound and NY Harbor could
also reach SCA thresholds.

SCA level wind gusts develop Tuesday afternoon with gale to
occasional storm force wind gusts Tuesday night into Wednesday.
Winds then back down to more SCA to low end gales Wednesday
night.

.HYDROLOGY...
No hydrologic impacts are expected thru Mon.

Flooding possible across the area Tuesday into early Wednesday,
including flash flooding. The total runoff would be enhanced
inland with melted snowfall. The Weather Prediction Center has a
segment of the area in a moderate risk for excessive rainfall
within parts of Northeast NJ and the Lower Hudson Valley with the
rest of the forecast region in a slight risk for excessive
rainfall.

.TIDES/COASTAL FLOODING...
Gale force E/NE winds tonight into Sunday morning will build
surge. Widespread minor coastal flooding expected along the
southern and eastern bays of LI and LI Sound with the Sunday
morning high tide. Elsewhere potential for localized minor
coastal flooding along NY/NJ harbor, Jamaica Bay, and NYC coast
along W LIS. Isolated dune erosion expected during the Sunday
morning high tide, overwashes not expected.

More significant coastal flood threat with the Wed AM high
tide. Potential for SE gale to storm force winds Tuesday Night,
bringing potential for widespread moderate to locally major
coastal flooding wit the Wed AM high tide. Along the
oceanfront, potential for 15-20 ft surf causing widespread dune
erosion and scattered overwashes. Localized dune
inundation/breaches possible where dunes have been compromised by
earlier storm events. More details on this event early next week.

.OKX WATCHES/WARNINGS/ADVISORIES...
CT...Winter Storm Warning from 4 PM this afternoon to 6 PM EST
Sunday for CTZ005-006.
Winter Weather Advisory from 6 PM this evening to 6 PM EST
Sunday for CTZ007-008.
Winter Weather Advisory from 4 PM this afternoon to 11 AM EST
Sunday for CTZ009-010.
Coastal Flood Advisory from 4 AM to 10 AM EST Sunday for
CTZ009>012.
NY...Winter Storm Warning from 4 PM this afternoon to 6 PM EST
Sunday for NYZ067>070.
Winter Weather Advisory from 4 PM this afternoon to 11 AM EST
Sunday for NYZ071.
Coastal Flood Advisory from 4 AM to 10 AM EST Sunday for
NYZ071-078-177.
Coastal Flood Advisory from 2 AM to 11 AM EST Sunday for
NYZ079-081.
Coastal Flood Advisory from 1 AM to 10 AM EST Sunday for
NYZ080-179.
NJ...Winter Storm Warning from 4 PM this afternoon to 6 PM EST
Sunday for NJZ002-103.
Winter Weather Advisory from 4 PM this afternoon to 11 AM EST
Sunday for NJZ004-104-105-107.
MARINE...Gale Warning from 5 PM this afternoon to noon EST Sunday for
ANZ331-332-340-345-350-353.
Gale Warning from 5 PM this afternoon to 5 AM EST Sunday for
ANZ335-338-355.

SYNOPSIS...JMC/JM
NEAR TERM...JMC/JC
SHORT TERM...JMC
LONG TERM...JM
AVIATION...JM/DR
MARINE...JMC/JM
HYDROLOGY...JMC/JM
TIDES/COASTAL FLOODING...