discussion on 2024-01-18

000
FXUS61 KOKX 181430
AFDOKX

Area Forecast Discussion
National Weather Service New York NY
930 AM EST Thu Jan 18 2024

.SYNOPSIS...
-- Changed Discussion --High pressure centered to the south slides offshore this
afternoon. Low pressure develops along the Mid Atlantic coast
tonight and passes east of the area on Friday. High pressure
builds south of the region through the beginning of next week,
then over the Atlantic for the middle of the week.-- End Changed Discussion --

.NEAR TERM /THROUGH TONIGHT/...
-- Changed Discussion --Forecast largely on track.

High pressure centered over the southeast will help keep
conditions relatively tranquil through the day. Temperatures
should moderate a bit compared to Wednesday, but still only
reach the upper 20s inland and low 30s near the coast.

Mostly cloudy to overcast conditions are expected as a weak
disturbance approaches from the west. While there may be some
weak returns on radar, think the day will remain dry overall as
the low levels are not saturated. An isolated flurry cannot be
ruled out across the interior this afternoon.

Tonight, shortwave energy rounding the trough aloft swings east
and begins to spur cyclogenesis off the Carolina coast. It`s
possible a few flurries or light snow develops toward daybreak,
though with dry air to contend with, this may hold off until
later in the morning. Temperatures overnight fall back into the
20s.-- End Changed Discussion --

.SHORT TERM /FRIDAY THROUGH FRIDAY NIGHT/...
-- Changed Discussion --Surface low pressure spins up off the Mid-Atlantic into Friday,
passing south and east of the region through the day. Meanwhile
an upper level low embedded in a trough over the Great Lakes
begins to interact with the surface low. This likely creates an
inverted surface trough over much of the Mid-Atlantic which will
help bring in moisture from the offshore low pressure. Forcing
from the upper level jet will aid lift along the inverted trough
at the surface which should allow for a shield of light snow to
develop over much of the area by Friday morning.

By mid-morning, much of the area should be enveloped in a light
snow. This snow continues through the day as the surface low pushes
to the east. Unlike recent events, profiles support all snow
down to the coast, with surface temperatures in the 20s and
lower 30s, and sufficient deep layered cold air aloft. The exact
placement and intensity of the offshore low and associated
inverted trough over the area plays a crucial role in the amount
of snow that falls over the area. There may be a relatively
sharp north to south cutoff of precipitation as subsidence and
dry air north of the surface trough may limit snowfall.
Additionally, any banding within the inverted trough may
locally enhance snowfall during the afternoon on Friday. Light
snow continues into late day or early evening, and impacts are
expected for the PM commute with falling snow and reduced
visibilities.

QPF is expected to be light, generally under a quarter inch
total, and thus, accumulations should be light, with 2-3 inches
across the NYC metro and Long Island, and 1-2 inches for the
Lower Hudson Valley and Southern Connecticut. While a relatively
minor event, whether by snowfall or travel impacts to the
Friday evening commute, a Winter Weather Advisory may eventually
be needed for portions of the area. Given the marginal
snowfall, and that the event is still just over a day out from
beginning, opted to hold off any any headlines to allow the day
shift to reevaluate.

Conditions dry as the low pulls away Friday night, another
round of arctic air filters in from the northwest. Lows Friday
night and into Saturday morning will once again be in the teens
most places. Wind chills Saturday morning may once again be in
the single digits to near 0 for inland areas.-- End Changed Discussion --

.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
-- Changed Discussion --A mid 1040s high centered near Omaha on Sat builds S of the area
thru Tue. It will be cold over the weekend with temps blw average.
NW winds will keep wind chills in the single digits and teens on
Sat, with wind chills dropping blw zero Sat ngt in the outlying
areas. Temps aloft warm a bit on Sun, so slightly warmer but highs
still likely aob freezing and wind chills in the teens and 20s. The
NBM was followed.

Heights rise Mon thru Wed with a further warming trend. By Tue,
projected highs are a degree or two abv normal. Some rain is
possible late Tue and Wed as GOMEX moisture begins to feed nwd into
the region. This setup could produce a wintry mix at times across
the interior, particularly Tue ngt. The NBM was followed.-- End Changed Discussion --

.AVIATION /15Z THURSDAY THROUGH MONDAY/...
-- Changed Discussion --High pressure will pass off to the south today. Low pressure
passes offshore Friday.

Mainly a VFR forecast through at least 06Z Friday. There could
be a brief period of MVFR this afternoon along with a chance of
flurries, mainly north and west of the NYC terminals. The prob
remains too low to include in the TAFs.

Snow develops in the 10-15Z Friday time period, with IFR likely
by around 15Z.

WSW winds may increase a bit along the coast during the late morning
and afternoon, but generally around 10 kt with a few gusts 15-17kt
possible. The wind direction should also back to the SW today. Winds
will then go light and variable for a time tonight before becoming
NE less that 10 kt. Winds increase to around 10kt during the
day Fri.

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

A few gusts 15-17kt possible late morning/early afternoon.

OUTLOOK FOR 12Z FRIDAY THROUGH MONDAY...

Friday...IFR with snow developing in the morning continuing
into the afternoon, ending in the early evening. NE-N wind gusts
20 kt in the afternoon and at night.

Saturday-Sunday...Mainly VFR. N-NW wind gusts 25-30 kt Saturday and
20-25 kt on Sunday.

Monday...VFR.

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

Monday...VFR.

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

.MARINE...
-- Changed Discussion --SCA is now only in effect for the ocean east of Moriches Inlet
through the afternoon. Sub SCA conditions are then expected on
all waters by this evening, persisting through Friday morning.
SCA conditions may redevelop Friday afternoon on the ocean with
gusts 25-30 kt.

A sca will most likely be needed on the ocean over the weekend, and
possible on the protected waters with mrgnl winds. A period sub-sca
cond late mon ngt into Tue, then winds and waves increase again late
Mon into Tue, before subsiding again by Tue ngt.-- End Changed Discussion --

.HYDROLOGY...
No hydrologic impacts are expected through the forecast period.

.OKX WATCHES/WARNINGS/ADVISORIES...
-- Changed Discussion --CT...None.
NY...None.
NJ...None.
MARINE...Small Craft Advisory until 4 PM EST this afternoon for ANZ350.-- End Changed Discussion --

SYNOPSIS...JMC/DR
NEAR TERM...DR/DS
SHORT TERM...DR
LONG TERM...JMC
AVIATION...JMC/JT
MARINE...JMC/DR
HYDROLOGY...JMC/DR