552
FXUS61 KOKX 191649
AFDOKX

Area Forecast Discussion
National Weather Service New York NY
1149 AM EST Sun Jan 19 2025

.SYNOPSIS...
Low pressure develops along the Mid Atlantic coast and pushes
northeast tonight. High pressure builds in Monday bringing an
arctic airmass to the area that remains over the area through
Friday. A weak system passes Tuesday night into Wednesday, with
an offshore low potentially impacting portions of the area in
the Thursday night/Friday period. A slight warming trend is
possible next weekend.

&&

.NEAR TERM /THROUGH TONIGHT/...
Radar reflectivity continues to show returns enhancing across
eastern PA, Northern NJ, and the Lower Hudson Valley. However,
with the airmass taking time to moisten, only seeing trace
amounts for liquid equivalents. Much of the guidance shows the
area north and west of NYC growing and expanding to the NE. This
is in response to the upper trough approaching. At the same
time, low pressure is developing along the North Carolina coast.
In between the upper trough and low, there may be a void for a
time north and east of NYC until the offshore low deepens and
the precipitation shield expands north and west of the low. This
will likely limit the eastward progression of the snow until
late this afternoon or early this evening across LI and eastern
CT.

Otherwise, light snow is expected to gradually move into the
area early this afternoon from the SW. Coastal locations will
likely see rain or a mix of rain and snow at the onset until
the intensity of the precipitation picks up. Snow becomes
moderate to locally heavy at times over the CWA late
afternoon/early evening. Heavier snow will be focused along any
mesoscale banding on the NW side of the cyclone, but will be
hard to pinpoint until it develops. Any location that is able to
be under a heavier snow band may overperform regarding snowfall
totals. The snow gradually dissipates from SW to NE tonight as
the low pulls to the northeast of the area. Most of the
accumulating snowfall should be done by midnight with only
residual snow showers possible over Eastern CT.

Snowfall totals are expected to be 6-8 inches for the warning
areas. The NYC metro will likely see anywhere from 4-6 inches,
with Long Island and coastal CT expecting 3-5 inches. It remains
very possible that any coastal area in the advisory see locally
up to 6 inches of snow, and/or a subsequent upgrade to a
warning, especially if the 12Z guidance shows higher liquid
equivalent amounts to the east. This will also likely depend on
how much initial mixing of rain occurs and the development of
any heavy snow banding.

&&

.SHORT TERM /MONDAY THROUGH MONDAY NIGHT/...
The low departs to the northeast by Monday morning with a strong
high pressure building in from the west. A tight pressure
gradient will bring a persistent NW flow with 20-25 mph gusts
through the day. This may result in blowing snow possibly
locally reducing visibilities at times.

The persistent NW flow and building high pressure will advect a
frigid airmass into the area. Highs on Monday will be in the
20s with wind chills making it feel like the teens and single
digits. Persistent wind Monday night should limit radiational
cooling but the building frigid airmass will allow temperatures
to fall into the single digits for most of the area. Wind chills
will however make it feel like anywhere from near 0 for Eastern
Long Island to -15 for portions of the interior Lower Hudson
Valley. Much of the area will see a wind chill value from 0 to
-10.

&&

.LONG TERM /TUESDAY THROUGH SATURDAY/...
No significant changes to the overall fcst thinking in the
extended. Went close to the NBM for temps thru the period, with
temps remaining blw freezing thru Fri, except at the coasts
where highs on Fri could hit the mid 30s. Potential for a period
of zonal flow over the weekend which is progged to produce
slightly milder temps. The placement of the polar front will be
difficult to pinpoint this far out, so temps could swing much
colder or warmer depending on where the boundary sets up. It
looks like the NBM is leaning towards the colder side attm.

Both the GFS and ECMWF have backed off on the lgt snow chcs for Tue
ngt into Wed, despite the passage of the upr trof. The NBM pops
however were still in chc category for most of the area, suggesting
that the consensus has not latched onto this trend yet. Will stick
with the higher pops for now and see if the trend holds.

Still chcs for snow now late Thu into Fri, especially ern and srn
areas with an offshore low. There is not solid agreement amongst the
models so confidence is low. NBM pops in the 20-30 range attm.

Potential for a frontal boundary to stall over the cwa during the
weekend. This could produce periods of mainly lgt pcpn, but
pinpointing the boundary this far out is very low confidence.

&&

.AVIATION /16Z SUNDAY THROUGH THURSDAY/...
Low pressure develops along the Mid Atlantic coast today,
passing to the southeast of the area tonight.

MVFR/VFR to start then conditions will lower to IFR/LIFR in
snow during the afternoon, persisting into this evening. The
snow tapers off 03-06Z, with VFR thereafter.

Winds veer to the N then NE today with speeds generally 10-12kt.
Winds become NW after 22-00Z, and increase significantly,
remaining strong thru Mon.

Expected Snowfall Accumulations:

NYC terminals, BDR, ISP: 4-6" HPN: 4-8" SWF: 5-8"

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

Amendments possible for the timing on snow this aftn. Ocnl gusts
possible aft 18-20Z.

.OUTLOOK FOR 12Z MONDAY THROUGH THURSDAY...

Monday: VFR. NW wind gusts 20-25 kt.

Tuesday: VFR. W wind gusts around 20 kt.

Wednesday: Chance of MVFR or lower in -SN, particularly coastal
terminals.

Thursday: VFR.

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

&&

.MARINE...
Wave heights near 5 feet are providing for a continued SCA on
the central and eastern ocean zones through today. Winds and
seas then increase tonight across all forecast waters as the low
pressure passes nearby. As the low pulls away tonight, SCA
conditions should prevail across all waters with a gusty WNW
behind another cold front. There will be a low end chance for
some gale gusts on the ocean.

Monday, widespread SCA conditions expected for all waters due to
wind gusts, for ocean both wind gusts and seas. Decreasing trend to
winds and seas Monday night, but ocean will probably still have SCA
conditions through Tuesday morning. Non-ocean waters stay below
SCA for Monday night. The ocean could have some lingering SCA
conditions Tuesday morning with otherwise below SCA conditions
for the waters. For Tuesday afternoon through Thursday, sub-SCA
conditions forecast for all waters.

Also, would expect some light freezing spray for tonight
through early next week for parts of the waters.

&&

.HYDROLOGY...
No hydrologic issues are anticipated through Saturday.

&&

.OKX WATCHES/WARNINGS/ADVISORIES...
CT...Winter Storm Warning until 4 AM EST Monday for CTZ005>008.
     Winter Weather Advisory until 4 AM EST Monday for CTZ009>012.
NY...Winter Storm Warning until 4 AM EST Monday for NYZ067>070.
     Winter Weather Advisory until 4 AM EST Monday for NYZ071>075-
     078>081-176>179.
NJ...Winter Storm Warning until 4 AM EST Monday for NJZ002-004-
     103>105-107.
     Winter Weather Advisory until 4 AM EST Monday for NJZ006-106-
     108.
MARINE...Small Craft Advisory from 6 PM this evening to 6 PM EST Monday
     for ANZ331-332-335-338-340-345.
     Small Craft Advisory until 7 AM EST Tuesday for ANZ350-353.
     Small Craft Advisory from 6 PM this evening to 7 AM EST
     Tuesday for ANZ355.

&&

$$

SYNOPSIS...JMC/MW
NEAR TERM...DW/MW
SHORT TERM...MW
LONG TERM...JMC
AVIATION...BC/JMC
MARINE...JMC/MW
HYDROLOGY...JMC/MW