000
FXUS61 KOKX 180508
AFDOKX
Area Forecast Discussion
National Weather Service New York NY
1208 AM EST Thu Jan 18 2024
.SYNOPSIS...
High pressure centered well south of the area overnight will
build offshore on Thursday. Low pressure develops along the
Mid Atlantic 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.
&&
.NEAR TERM /THROUGH TODAY/...
-- Changed Discussion --
Some minor adjustments for this update to account for latest
observations, but overall forecast remains on track for the
overnight.
High pressure continues to build south of the area 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 /TONIGHT THROUGH FRIDAY NIGHT/...
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
upper level low 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.
&&
.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
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.
&&
.AVIATION /05Z THURSDAY THROUGH MONDAY/...
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High pressure will pass off to the south overnight into
Thursday, while low pressure remains nearly stationary across
the Canadian Maritimes.
Mainly a VFR forecast. There could be a brief period of MVFR
Thursday afternoon along with a chance of flurries, especially
north and west of the NYC terminals.
W winds generally under 10 kt inland and 10-15 kt with gusts to
to around 20 kt along will gradually diminish overnight. WSW
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 on
Thursday. Winds will then go light and variable for a time
Thursday night before becoming NE less that 10 kt.
...NY Metro (KEWR/KLGA/KJFK/KTEB) TAF Uncertainty...
Gusts may be more occasional than frequent the next few hours.
A few gusts 15-17kt possible late morning/early afternoon
Thursday.
OUTLOOK FOR 06Z FRIDAY THROUGH MONDAY...
Late Thursday Night: VFR.
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-- End Changed Discussion --
&&
.MARINE...
SCAs have been extended on the ocean into Thursday, ending from
west to east into the afternoon. The primary reason for the
extension is due to lingering high seas, especially east of
Fire Island Inlet. 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 start 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.
&&
.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 6 AM EST early this morning for
ANZ331-332-335-338-340-345.
Small Craft Advisory until 4 PM EST this afternoon for ANZ350-
353.
Small Craft Advisory until 10 AM EST this morning for ANZ355.-- End Changed Discussion --
&&
$$
SYNOPSIS...JP/DW/MW
NEAR TERM...JP/DR/DW/MW
SHORT TERM...MW
LONG TERM...JP
AVIATION...JMC/DW
MARINE...JP/MW
HYDROLOGY...JP/MW