000
FXUS61 KOKX 172040
AFDOKX
Area Forecast Discussion
National Weather Service New York NY
340 PM EST Wed Jan 17 2024
.SYNOPSIS...
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High pressure building in to the south slides offshore Thursday
afternoon. Low pressure develops along the Carolina coast Thursday
night and passes east of the area on Friday. Arctic high
pressure builds in through the weekend, with the center of the
high passing well south for the beginning of next week. A
frontal system may impact the area by the middle of next week.-- End Changed Discussion --
&&
.NEAR TERM /THROUGH THURSDAY/...
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High pressure continues to build south of the area this evening and
overnight with mostly clear skies and a brisk W wind. Gusts may
approach 20kt along the coast. Cold temperatures continues tonight
with widespread lows in the teens. Frigid temperatures combined with
a brisk wind will allow wind chills to be in the single digits for
most of the area by early Thursday morning.
High pressure begins to slides offshore on Thursday with wind
diminishing toward mid-morning. Below average temperatures are once
again expected as the arctic airmass remains in place. Highs will
only be in the middle to upper 20s for the northern interior areas
with temperatures near freezing along the coast. As the next
disturbance approaches the area from the west, cloud cover likely
increases into the afternoon with a slight chance of light snow
showers for the northwestern portions of the area, though dry air at
the surface will likely prevent much of anything from reaching the
surface.-- End Changed Discussion --
&&
.SHORT TERM /THURSDAY NIGHT THROUGH FRIDAY NIGHT/...
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By Thursday night, the surface high has shifted offshore with the
next area of mid-level vorticity embedded in a trough sliding toward
the Mid-Atlantic coast. This will force a weak surface low pressure
to begin to develop overnight Thursday night and into Friday morning
off of the Carolina coast. 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 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.
Timing of the beginning of snowfall remains a bit uncertain as the
placement of the trough and intensity of the snow will have to
saturate the lower atmosphere before making it to the surface.
By mid-morning, much of the area should be enveloped in a light
snow. This light snowfall should continue through the day as the ULL
and surface low push to the east. The exact placement and intensity
of the offshore low and associated inverted trough over the area
will play 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.
As of now, snow totals of 2-3 inches are generally expected for the
NYC metro and Long Island with 1-2 inches expected for the Lower
Hudson Valley and Southern Connecticut. Some locations to the south,
mainly on Long Island, may approach 4 inches if a band of more
moderate snowfall develops. The higher amounts area expected to be
for areas further south where there is a better chance at seeing a
more moderate snowfall for a time as these areas will be closer to
the surface trough and offshore low.
Temperatures during the evening will be initially in the middle to
upper 20s and may rise to the upper 20s to low 30s by Friday
afternoon. This may result in initially a drier snowfall that
becomes a bit more wet by Friday afternoon, especially for areas to
the south. It will likely remain cold enough for there to be no
mixed precipitation types.
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/...
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The long term starts off with the an upper level trough moving
through the Northeast on Saturday. This will allow for a partly
sunny to mostly cloudy day with mainly dry conditions. Any lower
level forcing for precipitation in the form of a surface trough
looks to weaken during the day.
The arctic high pressure will bring 850 hPa temperatures on Saturday
of -15 to -20 C range to the area. NBM may have a hard time keying
on just how cold the upcoming air mass will be, so went a couple of
degrees below NBM guidance for highs on Saturday. Have high
temperatures in the upper teens to lower 20s for Saturday. Wind
chill values are expected to range from 0 to 10 above during the
warmest part of the day. Overnight lows in the teens for much of the
area, with some single digits above 0 possible for now. These may
end up being too warm if skies clear out quickly enough. Overnight
wind chill values of 10 below to 5 above 0 are forecast.
Conditions will be breezy due to the arctic high and the low off
shore strengthening on Saturday, increasing the pressure gradient
across the area. Northwest winds of 10 to 15 mph with gusts of 20 to
25 mph are expected. Isolated gusts of around 30 mph is possible.
The upper level shortwave pushes off shore Saturday night, allowing
for some clearing. The high continues to build into the region
through the weekend, with the center of the high passing off the
Southeast US Coast on Monday. The next system to affect the region
may come by the middle of next week as a cold front approaches from
the north.
Temperatures moderate Sunday into the middle of next week, with
highs on Sunday in the 20s inland to near freezing along the coast.
Near normal temperatures are expected on Monday, with a return to
above normal temperatures by Tuesday.-- End Changed Discussion --
&&
.AVIATION /21Z WEDNESDAY THROUGH MONDAY/...
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VFR as high pressure builds in through tonight and then shifts
offshore on Thursday.
W winds generally around 15 kt with gusts 20-25 kt will continue
into early this evening. Sustained winds and gusts will begin
diminishing after 00-03z, but gusts around 20 kt could linger
especially near the coast. W-WSW winds may then weaken below 10 kt
briefly towards day break Thursday before increasing to around 10 kt
late Thursday morning and afternoon. The wind direction should also
back to the SW on Thursday.
...NY Metro (KEWR/KLGA/KJFK/KTEB) TAF Uncertainty...
Gusts may end 1-3 hours sooner than in TAF tonight.
OUTLOOK FOR 18Z THURSDAY THROUGH MONDAY...
Thursday Afternoon-Night: VFR.
Friday...IFR with snow developing in the morning continuing into the
afternoon and 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-- End Changed Discussion --
&&
.MARINE...
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A SCA is in effect for all waters through early Thursday morning as
wind gusts remain near 25 kt and wave heights on the ocean remain 5-
7 feet. Near 25 kt gusts may persist into mid-morning Thursday but
are expected to diminish by noon, so an extension of the SCA may be
needed in some places, especially the ocean waters. Sub-SCA
conditions are then expected by Thursday evening and lingering into
Friday morning. SCA conditions may then redevelop Friday afternoon
on the ocean with gusts 25-30 kt.
SCA likely on all waters for Saturday with a strengthening arctic
high building into waters from the west. Northwest winds could gust
25 to just under 35 kt. An isolated gust to gale force is possible,
especially on the ocean waters during the day Saturday. Winds
diminish somewhat Saturday night, but moreso Sunday night.
Waves on the ocean stat off at 3 to 5 ft on Saturday, then increase
to 4 to 7 ft by Saturday night, then diminish to below 5 ft by
Sunday morning. Waves are then expected to remain below 5 ft through
the beginning of next week.-- End Changed Discussion --
&&
.HYDROLOGY...
No hydrologic impacts are expected through the forecast period.
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
CT...None.
NY...None.
NJ...None.
MARINE...Small Craft Advisory until 6 AM EST Thursday for ANZ331-332-
335-338-340-345-350-353-355.
&&
$$
SYNOPSIS...JP/MW
NEAR TERM...MW
SHORT TERM...MW
LONG TERM...JP
AVIATION...DS
MARINE...JP/MW
HYDROLOGY...JP/MW