discussion on 2024-01-30

000
FXUS61 KOKX 310205
AFDOKX

Area Forecast Discussion
National Weather Service New York NY
905 PM EST Tue Jan 30 2024

.SYNOPSIS...
An upper level disturbance moves across the region tonight into
Wednesday morning. High pressure will otherwise remain over New
England into Wednesday night. A cold front approaches from the
north and west Thursday, moving through Thursday night. High
pressure then gradually builds in from Southeastern Canada
Friday and remains in control into the beginning of next week.

&&

.NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/...
-- Changed Discussion --Maintained PoPs for NE NJ, NYC metro, lower Hudson Valley, and
western Long Island, for periodic light rain/snow showers
tonight. Terminal radar at KJFK indicates pockets of precipitation
have already developed in this general area as a light SW flow
steers shallow surface moisture inland. A dusting or light
coating is possible in a few spots, but temperatures remain in
the low to mid 30s, so impacts should be limited. Forecast
remains on track.

A ridge axis this evening will give way to a shortwave late
tonight into early Wednesday. Surface high pressure over the New
England coast will largely remain in place tonight, but the
flow around the high will continue becoming a light SE. The
combination of the approaching shortwave and onshore/upslope
flow appear enough to support lift for some snow showers across
NE NJ and portions of the Lower Hudson Valley. Most of the 12z
hi-res guidance has a light reflectivity and light qpf signal in
these areas.

The main concern revolves around the level of saturation aloft
for snow growth. The moisture layer is shallow with a dry slot
above about 6-7kft. The upslope flow should be enough of a
lifting mechanism to generate precipitation and the SE flow off
the ocean should provide condensation nuclei for snow. While
the dendritic snow growth zone is dry, there appears to be just
enough saturation between -7 to -9C to support small snow
crystals likely in the form of needles. If the saturation layer
is thinner, then it may be more difficult for snow to grow in
which case some light rain/freezing rain is possible.
Temperatures for the most part should fall to freezing or just
below away from the urban NE NJ corridor. Light freezing rain is
not currently mentioned, but is something that will need to be
monitored if snow growth is less than anticipated.

The focus for snow showers should mainly be west of the NYC
metro, but there could be some flurries or brief snow showers
nearby overnight. Have bumped PoPs up to chance for NE NJ and
portions of Lower Hudson Valley tonight given the latest trends.
Any snow accumulation looks to be on the light side and under
an inch.

Otherwise, overcast conditions will continue tonight with
moisture trapped below a subsidence inversion. Lows will range
from the middle to upper 20s inland and eastern Long Island to
the lower to middle 30s elsewhere.-- End Changed Discussion --

&&

.SHORT TERM /6 AM WEDNESDAY MORNING THROUGH WEDNESDAY NIGHT/...
The axis of the shortwave will shift south and east of the area
Wednesday morning. Any lingering snow showers in NE NJ/Lower
Hudson Valley should dissipate shortly after 12z.

Heights will begin rising behind the shortwave with ridging
building through Wednesday night. High pressure will remain in
control at the surface. The main challenge for the rest of
Wednesday will be with the amount of cloud cover. Model
soundings continue to indicate a subsidence inversion between
4-5kft. Consensus blends are showing some improvement with the
amount of cloud cover in the afternoon, especially across Long
Island and southeast Connecticut. However, given recent trends
with guidance too quick to improve sky conditions have gone with
a mostly cloudy forecast on Wednesday. There is not much
difference with soundings Wednesday night and will continue with
mostly cloudy conditions. Highs will be close to normal in the
upper 30s inland and lower 40s near the coast. Temperatures
Wednesday night will be in the upper 20s inland and lower 30s
near the coast.

&&

.LONG TERM /THURSDAY THROUGH TUESDAY/...
A weak cold front and low pass through the region Thursday
into Thursday night with slightly above normal temperatures.
Then, the remainder of the long term period, Friday into the
beginning of next week, will be tranquil, with near normal
temperatures, as high pressure builds in from Central Canada
Friday and remains through Tuesday.

The forecast remains very similar with the previous forecast
as a weakening northern stream surface low and upper shortwave
approach from central Canada early Thursday, with the low moving
to the east and the cold front passing through Thursday night.
The upper trough does begin to amplify late Thursday night into
Friday as the cold front moves to the south and east of the
region. There is very little lift ahead of and with the cold
front, and moisture is limited to the lower levels. Continuing
with the slight chance probabilities, and with the warm
temperature profiles, light rain showers or sprinkles will
dominate. Thursday night, in the colder air, some snow showers,
or flurries may mix in with the rain before coming to an end.
Canadian high pressure then builds in Friday and remains into
the beginning of next week.

&&

.AVIATION /02Z WEDNESDAY THROUGH SUNDAY/...
High pressure slowly builds down the New England coast while a
disturbance passes south of the region into Wednesday morning.

Ceilings will generally vary between 3000 to 3500 ft into early
evening before becoming predominantly MVFR tonight. There is
also a chance of IFR tonight in snow showers, primarily at KEWR,
KTEB, and KSWF, though cannot be ruled out for KLGA or KJFK.
Most sites will return to VFR late Wednesday morning, though
likely remaining under 4000 ft through the day.

Light SE flow veers southerly, then southwesterly on Wednesday,
speeds remaining under 10 kt.

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

Ceiling fluctuate between 3000-3500 ft early this evening,
amendments possible for changing categories.

Chance of IFR in snow showers tonight, especially at KTEB and
KEWR.

OUTLOOK FOR 00Z THURSDAY THROUGH SUNDAY...

Wednesday Night through Thursday: VFR. SW winds G15-20kt
Thursday afternoon.

Thursday Night and Friday: Chance of MVFR or lower conditions
in rain showers, possibly mixing with SN Fri. NNW winds
G15-20kt Friday.

Saturday and Sunday: VFR.

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

&&

.MARINE...
-- Changed Discussion --Seas on the ocean have largely fallen below 5 feet, and the
advisory that was in effect for waters east of Moriches Inlet
has been ended. Long period E-SE swells will continue through
Wednesday night on the waters. Winds on the waters will remain
below SCA levels with a weak pressure gradient in place through
Wednesday night.

Marginal SCA conditions are possible on the ocean waters Thursday
ahead of a cold front, in a southwest flow. Then behind the cold
front Friday night into early Saturday SCA gusts will be possible on
the ocean waters in a northwest flow. Winds and seas remain below
advisory levels across all the waters late Saturday through early
next week as high pressure remains in control.-- End Changed Discussion --

&&

.HYDROLOGY...
No hydrologic impacts are expected into early next week.

&&

.OKX WATCHES/WARNINGS/ADVISORIES...
-- Changed Discussion --CT...None.
NY...None.
NJ...None.
MARINE...None.-- End Changed Discussion --

&&

$$

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