000
FXUS61 KOKX 120537
AFDOKX
Area Forecast Discussion
National Weather Service New York NY
1237 AM EST Mon Feb 12 2024
.SYNOPSIS...
High pressure building from the west into the area will weaken
on Monday as deepening low pressure approaches from the
southwest. A secondary low developing near the Delmarva region
Tuesday morning will pass south and east of Long Island later
Tuesday. High pressure will return from Wednesday into Thursday
before an Alberta Clipper low passes through Thursday night into
Friday. Another low may impact the region next weekend.
&&
.NEAR TERM /UNTIL 6 AM THIS MORNING/...
Forecast remains on track, with only minor changes needed.
Previous discussion follows.
Still seeing mostly cloudy skies this evening, but anticipate
clearing to occur tonight with partly cloudy to mostly clear
conditions overnight. Along with light winds there should be
enough radiational cooling to get temps down into the upper 20s
inland and and across the Long Island Pine Barrens, ranging
through the 30s elsewhere, to the upper 30s in NYC.
&&
.SHORT TERM /6 AM THIS MORNING THROUGH 6 PM TUESDAY/...
* Confidence is high across the interior for 6+ inches of snow
late Monday night into Tuesday. Winter Storm Warnings are
now in effect for interior NE NJ, the Lower Hudson Valley, and
interior southern CT.
* A plowable, advisory level snow is likely for Southern
Westchester, coastal CT and portions of NE NJ west of the I-95
corridor.
* Uncertainty remains on the exact track of the deepening low
and timing of transition to snow in the NYC metro and Long
Island corridor.
Weak high pressure will be across the area to start on Monday
with even some sunshine before high level clouds arrive later
in the afternoon. It will still be mild with highs getting up to
45-50.
Model guidance continues to show deepening low pressure
approaching from the SW late Monday, with secondary low
development near the Delmarva Tuesday morning and then passing
S/E of Long Island through the day toward or just SE of the
40N/70W benchmark.
Without a damming high in place to the north and warm nose
intruding aloft per 12Z guidance, the metro area and the coast
will start off as rain. Inland precip should start off as snow,
with perhaps a brief period of rain at the onset. Coastal
locations will be the last to turn over to snow, with NYC and
Long Island likely not happening until around or after daybreak.
Closer to the coast, the best chance for advisory level snows
will be coastal CT and portions of NE NJ west of the I-95
corridor, with about an inch NYC and Long Island, maybe up to 2
inches in the N Bronx/N Manhattan and along the north shore of
Long Island.
An earlier change to snow cannot totally be ruled out, and could
lead to 6-inch amounts all the way down to the CT coast and
closer to NYC and the NJ urban corridor, and advy level amts
into the rest of the CWA.
The precipitation will start after midnight from SW to NE,
becoming heaviest in the pre-dawn hours and continuing through
the morning, ending from west to east in the afternoon.
Northerly winds will gust between 25 and 35 mph on Tuesday, with
gusts to 40 mph in the afternoon near the coast. This combined
with heavy snow could limit visibilities to less than 1/2 mile.
However, a limiting factor for the blowing and drifting will be
that this looks to be a mainly wet snow. Temperatures across the
interior will drop to either side of 30 by daybreak Tue, to near
freezing along coastal CT into most of NE NJ, and the mid 30s
for NYC and Long Island, which should limit how quickly the
snow starts accumulating.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/...
There has not been too much change to the forecast thinking
Tuesday night into next weekend.
*Key Points*
* Temperatures look to be below normal with mainly dry
conditions this period.
* A fast moving clipper system passes across the northeast
Thursday night.
* Forecast confidence lowers next weekend as there are some
indications of another low pressure moving near the region.
The storm system that impacts the area Tuesday quickly departs
well offshore Tuesday night. High pressure builds towards the
eastern seaboard on Wednesday. The ridge axis will be over the
area Wednesday night before shifting offshore on Thursday. The
deterministic and ensemble means are in good agreement on this
scenario. A fast moving Alberta Clipper low continues to be
signaled on the guidance for Thursday night. A general consensus
has the surface low passing over New England. Overall moisture
is limited, but there should be a brief period of lift to
continue with chances of precipitation. NBM precip probabilities
support predominately snow showers inland, but a mix of rain
and snow showers to the coast. The more northern track of the
clipper low would introduce slightly milder air towards the
coast. If the low were to trend further south, colder air and
higher chances of a period of snow showers could occur across
the entire area. It is important to note this is a fast moving
system which limits the amount of precip that could fall.
The modeling diverges Friday into the upcoming weekend. Another
fast moving northern stream shortwave may approach next Saturday
and could have some interaction with a southern stream system.
Other guidance hints that the northern stream may be suppressive
limiting any precip chances and low pressure development. It is
still much too early for any details on p-types and impacts as
each scenario seems plausible. For now NBM slight chance PoPs
Saturday into Saturday night look reasonable.
&&
.AVIATION /06Z MONDAY THROUGH FRIDAY/...
-- Changed Discussion --
High pressure remains in control through Monday afternoon. A
coastal storm approaches from the southwest late Monday
afternoon into Monday night.
VFR conditions expected tonight through the day Monday and into
the first half of Monday night. MVFR or lower expected around
or just after 06Z Tuesday as precipitation begins to move in for
the metro terminals, likely starting as all rain, changing to a
rain/snow mix beginning between 10-12z Tuesday morning and into
early Tuesday morning as colder air moves into the area. There
is a low end chance that some ice pellets mix in during the
transition from rain to snow, but this should be brief and
confidence is not high enough to include in the TAF. KSWF will
start off as all snow.
NW flow at 10 kt or less should become lighter tonight. Sea
breeze directions with winds remaining under 10 kt anticipated
late Monday morning into the afternoon.
...NY Metro (KEWR/KLGA/KJFK/KTEB) TAF Uncertainty...
No unscheduled amendments expected through 00z Tuesday.
OUTLOOK FOR 06Z TUESDAY THROUGH FRIDAY...
Monday night...IFR or lower conditions likely. At KSWF/KHPN,
precipitation is expected to start and remain all snow. At KBDR and
KGON, precipitation may start off as a rain/snow mix, then changing
to all snow late Monday night. Elsewhere, rain possibly mixing with
snow or sleet towards daybreak. NE winds 10-15 G20-25 kt late,
highest NYC metro/coast.
Tuesday...IFR or lower cond likely. Any rain changes to all snow
through the morning. Some sleet may mix in early in the morning.
Snow tapering off from W-E during the afternoon, with cond possibly
becoming VFR late. NE-N winds 15-20 G25-30kt, becoming NW in the
afternoon.
Tuesday night through Wednesday night...VFR. NW winds 10-15G20kt
daytime, and 10-15G20kt at night.
Thursday: VFR.
Thursday night: Chance of MVFR and snow showers. NW winds 10-15G20-
25kt late.
Friday: VFR. NW winds 10-15G20-25kt.
Detailed information, including hourly TAF wind component forecasts,
can be found at: https:/www.weather.gov/zny/n90-- End Changed Discussion --
&&
.MARINE...
Swell of 3 ft will subside slightly tonight into Mon, with quite
conditions.
NE winds increase Monday night ahead of an approaching deepening
low pressure system from the southwest. The low then passes just
south and east of the ocean waters on Tuesday. This will allow
winds to reach gale force on the ocean on Tuesday, with a gale
warning now in effect. A few gusts to 35 may also be possible on
the eastern Sound and the bays of Long Island, with SCA cond
elsewhere.
Winds on the waters will weaken somewhat Tuesday night as the
storm system departs. This will be short-lived as high
pressure builds in from the west Wednesday increasing the
pressure gradient. SCA winds are likely on all waters and there
is even a chance for gale force gusts on the ocean. Winds begin
to weaken on the non-ocean waters Wednesday night could remain
near SCA levels on the eastern Bays and easter LI Sound with
ocean still 25-30 kt. Winds should fall below SCA levels
Thursday before potentially reach SCA levels Friday behind a
departing Clipper low pressure. Ocean seas will be elevated
Tuesday night through Wednesday night before briefly subsiding
below 5 ft Thursday. Elevated seas are possible to end the week.
&&
.HYDROLOGY...
There are no hydrologic issues expected at this time.
&&
.TIDES/COASTAL FLOODING...
* Minor coastal flooding is likely across multiple high tide
cycles through Monday night.
* Widespread minor and some moderate coastal flooding becoming
more likely with the Tuesday morning/midday high tides.
Latest forecast is heavily based on Stevens NYHOPS guidance,
which has been performing reasonably well over the past 24
hours.
Have decided to leave the coastal flood statement for coastal
Fairfield/Westchester running tonight through Monday early
afternoon with the expectation of minor thresholds just being
reached at the Stamford and/or Bridgeport gauges for the next
couple of high tide cycles. No flooding otherwise expected for
tonight.
For Monday`s daytime cycle, the coastal flood advisory for the
south shore of Nassau County remains in effect. A statement
might be needed for Queens with parts of Jamaica Bay potentially
touching minor flooding.
A more widespread minor flooding event is possible for Monday
night, but with this still 3 high tide cycles away and not
enough confidence regarding coverage, have not yet issued an
advisory. The exception being southern Nassau County, where
confidence is high enough. Areas that might eventually need an
advisory include southwestern Suffolk, southern Queens, southern
Brooklyn, Lower NY Harbor and parts of western Long Island
Sound.
For Tuesday`s daytime cycle, there`s enough confidence in
moderate flooding to put up a coastal flood watch for Southern
Nassau County. Localized moderate coastal flooding is possible
for Southwestern Suffolk County. Otherwise, widespread minor
coastal flooding is looking more probable for all but along
the eastern Sound and along Peconic/Gardiners Bays. Just like
Monday night, there`s still time to gain more confidence in the
extent of minor flooding before issuing headlines. Timing of a
wind shift from NE to N on Tuesday brings some uncertainty on
how quickly some drainage help could occur as well as the amount
of time the north shore of Long Island is exposed to a more
direct onshore flow.
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
-- Changed Discussion --
CT...Winter Storm Warning from 1 AM to 6 PM EST Tuesday for
CTZ005>008.
NY...Winter Storm Warning from 1 AM to 6 PM EST Tuesday for
NYZ067>070.
Coastal Flood Advisory from 8 AM this morning to 10 AM EST
Tuesday for NYZ179.
Coastal Flood Watch from Tuesday morning through Tuesday
afternoon for NYZ179.
NJ...Winter Storm Warning from 1 AM to 6 PM EST Tuesday for NJZ002-
103.
MARINE...Gale Warning from 6 AM to 6 PM EST Tuesday for ANZ350-353-355.-- End Changed Discussion --
&&
$$
SYNOPSIS...BG/DS
NEAR TERM...BG/JP/DS
SHORT TERM...BG
LONG TERM...DS
AVIATION...BC/JP
MARINE...BG/DS
HYDROLOGY...BG/DS
TIDES/COASTAL FLOODING...