discussion on 2024-02-15

000
FXUS61 KOKX 152130
AFDOKX

Area Forecast Discussion
National Weather Service New York NY
430 PM EST Thu Feb 15 2024

.SYNOPSIS...
-- Changed Discussion --Offshore high pressure giving way to an approaching low pressure
tonight that will strengthen and pass northeast of the region
late tonight into Friday. Region will be in between lows
Friday, the next one is moving into the Appalachians. This low
approaches Friday night and moves southeast of Long Island
Saturday. This coastal low will continue to head away from the
area Saturday night. Another low will pass to the north Sunday
night. High pressure then builds in Monday and remains in
control through mid-week.-- End Changed Discussion --

.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
-- Changed Discussion --Clouds increasing as they move in from west to east closing out
this afternoon. Mainly dry conditions are expected although a
few snow showers will be possible into early evening north and
west of NYC as a fast moving low approaches the region.

This low will be deepening slightly as it goes to the NY/VT
border this evening into start of overnight. Then the low moves
to the Gulf of Maine by early Friday and deepens further to
near 995mb.

Precipitation will be mainly in the form of snow showers as the
low center traverses to our north. The associated warm front
moves across this evening and followed quickly by an associated
cold front with the occluded front passing by to the north. Light
snow amounts are forecast up to near a half inch to 1 inch.
Highest amounts relatively speaking will be across the interior
sections of the region. Little to no snow accumulation expected
along the coast.

The pressure gradient steepens tonight with the development of
higher westerly flow and more westerly gusts behind the cold
front. Strong cold air advection also will be occurring. Gusts
develop especially towards daybreak Friday. Forecast model
BUFKIT soundings indicate most gusts near 40 mph but some
occasional higher gusts will be possible up to near 45 to 50
mph. Higher elevations across the interior may also see
relatively higher gusts.

Coverage both temporally and spatially of gusts above 45 mph is
too low to warrant any wind advisories at this time.

The snow cover across the interior will keep interior locations
colder and allow for less efficient vertical mixing compared to
along the coast.

These winds will mix the boundary layer and keep less spatial
range of lows, mainly upper 20s to lower 30s. Sky conditions
lower overnight with dry conditions as mid level negative
vorticity advection enters.-- End Changed Discussion --

.SHORT TERM /6 AM FRIDAY MORNING THROUGH SATURDAY/...
-- Changed Discussion --On Friday, the low moves farther out into the Atlantic with
steep pressure gradient remaining. Gusty winds will remain in
the morning and then lessen into the afternoon as the low moves
farther away and the pressure gradient relaxes. Gusts near 40 to
45 mph early will lessen to 30 to 35 mph in the afternoon.

The dry conditions continue along with mostly sunny sky conditions
Friday with some slight ridging aloft. High temperatures forecast
are in the upper 30s to lower 40s.

Large scale numerical weather prediction model guidances depicts
some variations of track with the wave of low pressure Friday night
into Saturday. 12Z model runs convey a remarkable difference where
the NAM and GFS models have the low east of Virginia by 12Z Saturday
whereas the Canadian and ECMWF models have the low east of Maryland
and Delaware by 12Z Saturday. 18Z NAM has shifted farther north
compared to its 12Z run.

The vertical forcing for precipitation comes from these upper level
features. In the mid levels, a longwave trough approaches with its
embedded higher positive vorticity advection traversing the area
early Saturday. In the upper levels, a strong westerly jet streak (
around 190 kt at 250mb) will be south of the area with its left
front quad near the region during the day Saturday.

Current forecasts have for Lower Hudson Valley and Southern
Connecticut up near 1 inch snow with snow in the 1 to 2 inch
range to the south across the remainder of the forecast region.
The forecast for this snow is low to medium confidence.

Subsequent model runs may show more northward trends and as eluded
to in the SREF with some of its members, there is a chance
(currently a low chance) that snowfall totals for this event could
end up in the advisory range with snowfall totals near 3 to 4
inches.-- End Changed Discussion --

.LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/...
-- Changed Discussion --Generally a quiet period in the long term with an upper level trough
over the Northeast Saturday night and a departing coastal storm at
the surface. Surface ridging will build into the area behind the
coastal storm. For Sunday, a weakening area of low pressure at the
surface approaching New England from the Great Lakes. This low
passes north of the area Sunday night. With much of the dynamics
remaining north of the area, no precipitation is expected with this
low. However, it will send a weak, dry cold front through the area
late Sunday night into early Monday morning.

The upper level trough exits the region on Monday, being replaced
with near zonal flow through Tuesday night. A weak upper level
shortwave approaches from the west late Tuesday night into
Wednesday, inducing a coastal storm off the Southeast Coast. This
storm is currently forecast to remain well offshore as the area
remains protected by the surface high pressure that is expected to
push off the New England coast Tuesday night. This high will extend
along much of the eastern seaboard through the mid-week period.

Temperatures will remain near or slightly below normal through
Tuesday, then as the high pushes off the New England Coast and a
southerly flow develops, temperatures are expected to be slightly
above normal Wednesday and Thursday.-- End Changed Discussion --

.AVIATION /21Z THURSDAY THROUGH TUESDAY/...
-- Changed Discussion --Low pressure approaches this evening, sending a frontal system
across the region. The low quickly moves off the New England coast
late tonight into Friday morning as high pressure builds to the
west.

VFR through early this evening. Snow showers, potentially mixed with
some rain near the coast, are possible around 23/00z to 05/06z west
to east. This precipitation may briefly lower conditions to MVFR
with a low potential of IFR. VFR quickly returns after the snow
showers end 03-06z.

S-SSW winds around 10 kt or less to start, but should begin
increasing ahead of the approaching system. There may be some gusts
around 20 kt this evening. Behind the frontal passage, winds quickly
shift to the W and then NW overnight. Speeds increase to 15-20 kt
with gusts 25-30 kt. There is a chance a few gusts 35-40 kt 09-15z.
NW winds should slowly weaken into Friday afternoon with gusts
closer to 20 kt late in the day.

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

Gusts this evening may be occasional at KJFK, KLGA, and KEWR.

Snow showers this evening may briefly mix with some rain. Low chance
for a brief drop to IFR in this activity.

Timing of wind shift to the W and NW overnight may be off by 1-2
hours.

OUTLOOK FOR 18Z FRIDAY THROUGH TUESDAY...

Friday Afternoon: VFR. NW winds 15G25kt diminishing late.

Friday Night-Saturday. MVFR or lower possible late Friday night into
Saturday morning in light snow. VFR later Saturday with NW wind
gusts 20 kt.

Sunday: VFR. WSW wind gusts 25-30 kt.

Monday-Tuesday. 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 --For the forecast waters short term marine forecast tonight
through Saturday, the following is noted as stated below.

Seas and winds ramp up quickly late this evening into overnight.
SCA level wind gusts this evening will rise towards gales late
this evening and more into gales overnight. The gales continue
into Friday morning and wind gusts return to SCA levels Friday
afternoon. Winds are forecast to drop below SCA levels Friday
night and remain below SCA Saturday morning before rising to SCA
levels for most waters Saturday afternoon. Ocean seas build to
SCA levels tonight and remain at SCA levels Friday and
eventually lower below SCA west to east on the ocean Friday
night. Seas are below SCA for all forecast waters Saturday. Non-
ocean waters are below SCA in the short term except for Long
Island Sound late tonight into Friday.

Winds diminish Saturday night as a coastal storm moves away
from the region. Though SCA gusts are still possible on the
western ocean zone for the first half of Saturday night. Winds
then increase to 25 to 30 kt on all waters Sunday as the
pressure gradient increases thanks to an approaching low that
will pass to the north into Monday night. Waves also quickly
build on Sunday on the ocean waters to 5 to 10 ft. Winds
diminish Sunday night, however the eastern sound and Peconic and
Gardiner`s Bays along with the ocean waters will remain at or
above 25 kt through Sunday night. Waves on the ocean diminish
during this timeframe, but remain above 5 ft on the ocean.

Sub-SCA conditions expected by Monday afternoon on all waters.
Thereafter, conditions are expected to remain below SCA criteria on
all waters through mid-week.-- End Changed Discussion --

.HYDROLOGY...
No issues expected through mid next week.

.OKX WATCHES/WARNINGS/ADVISORIES...
-- Changed Discussion --CT...None.
NY...None.
NJ...None.
MARINE...Gale Warning until 1 PM EST Friday for ANZ331-332-335-338-340-
345-350-353-355.-- End Changed Discussion --

SYNOPSIS...JM/JP
NEAR TERM...JM
SHORT TERM...JM
LONG TERM...JP
AVIATION...DS
MARINE...JM/JP
HYDROLOGY...JM/JP