220
FXUS61 KOKX 040605
AFDOKX
Area Forecast Discussion
National Weather Service New York NY
105 AM EST Wed Dec 4 2024
.SYNOPSIS...
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High pressure over the Tennessee Valley will remain in control
through the overnight and early Wednesday as it slides farther
southeast and eventually off the southeast coast. A strong
clipper low will pass to the north and impact the area Wednesday
night through Thursday night. High pressure builds back in from
the west Friday and into the weekend, sliding offshore Sunday.
An area of low pressure may then approach the region early next
week.-- End Changed Discussion --
&&
.NEAR TERM /UNTIL 6 AM THIS MORNING/...
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Snow showers/flurries have cleared eastern most areas. Mainly
clear conditions are expected for the remainder of the overnight
as the shortwave that brought snow showers and flurries to
portions of the area moves farther out to sea. Winds overall are
subsiding no as the initial shot of CAA in association with the
shortwave has ended. Thus, overall expect lighter W to NW winds
for the remainder of the night.
High pressure centered over the Tennessee Valley will remain in
control through the near term and will continue to slide
farther southeast. The pressure gradient over our area weakens
slightly tonight, and in turn, the winds weaken. Stuck mainly
with the NBM for lows for now, but given little cloud cover,
some areas may be able to cool below current forecast lows. MOS
guidance was not too much lower than the NBM, so manually
lowered the usually cool spots a couple of degrees lower than
the NBM.-- End Changed Discussion --
&&
.SHORT TERM /6 AM THIS MORNING THROUGH THURSDAY NIGHT/...
The aforementioned high that will be sliding to our south will move
offshore by Wednesday afternoon. In response to this and an
approaching clipper low, mid and high level clouds increase and
winds become southwesterly. Highs could reach the low 50s across
Long Island and the coast, but most will see highs in the 30s to low
40s.
The aforementioned clipper low will impact the area Wednesday night
through Thursday night. Potent shortwave energy that originated from
near the north pole will dive down and aid in deepening this low as
it passes to our north. The GFS continues to show the upper level
trough becoming negatively tilted just to our west, but other
guidance has this happening later or not at all. Regardless,
this system will bring rain, snow, strong winds and cold air.
There has been little change in the precipitation forecast. The
rain/snow line as been pretty steady across guidance for several
cycles now. All snow is expected across the Lower Hudson Valley and
interior NJ and CT to start Wednesday night, becoming a rain snow
mix Thursday morning and then ending as lighter snow later on
Thursday. The highest QPF continues to be out east where all rain is
expected, so as far as snow totals go, still expecting sub-Advisory
totals (few hundredths to a couple of inches). There will be periods
of moderate rainfall across the Twin Forks and eastern CT. Rainfall
totals there will be between 0.50 and 0.75 inches. No hydrologic
impacts are expected.
The more impactful weather from this system will likely be the
strong winds. A Wind Advisory is now in effect for the entire area.
SW winds pick up Wednesday evening and night, but winds and gusts
look to peak Thursday behind the cold front with deep mixing in cold
air advection. There is good consensus in NAM and GFS forecast
soundings that the mixed layer at least briefly reaches 800mb
(~2km). The NBM also has the mixed layer depth around 1.5-2.0km
Thursday afternoon. Winds at that level look to be 45 to 50
knots. With strong cold advection this should lead to at least a
period of 45 to 50 mph wind gusts at the surface.
Winds gradually lower Thursday night. Cold air rushes in behind the
system and lows should be in the 20s for most. Combined with the
winds, wind chill values will be in the single digits and teens.
&&
.LONG TERM /FRIDAY THROUGH TUESDAY/...
Key Points:
* A chilly and windy Friday.
* High pressure and gradual warming Saturday and Sunday.
* Uncertainty surrounding rain chances Monday-Tuesday.
As the Alberta Clipper low continues to exit far to our northeast on
Friday, high pressure simultaneously builds in from the west. A
tight pressure gradient remains to start Friday, but gradually
relaxes into the evening. NW wind gusts between 25-35 mph are
possible into the early afternoon, before gradually subsiding in the
late afternoon and evening on Friday as they turn to a more westerly
direction.
Much cooler air filters in post-front, leading to a cold Friday with
highs in the 30s. Some interior areas are currently forecast to
barely stay below freezing Friday afternoon. Given the breezy
weather, wind chills will be in the 20s across the area Friday
afternoon. Friday night, lows will be in the 20s to mid-teens. A
bias-corrected model blend (BCCONSAll) was used for low temperatures
Friday and Saturday night to account for colder spots due to
radiational cooling, since winds would be lighter, allowing more
radiational cooling.
High pressure moves nearby Saturday then to our south and southeast
Saturday night into Sunday, bringing winds in from a more
southwesterly direction. This will lead to gradual warming through
the weekend. Highs on Saturday remain in the 30s for most, but a few
southern coastal areas may reach the low-40s. Saturday night lows
will be in the low-20s to near freezing. Sunday will be much warmer
a heights build aloft under a longwave ridge and warm air advection
takes place at 850mb along with a continued SW wind. Highs will be
in the low/upper-40s on Sunday then into the upper-20s to upper-30s
Sunday night.
Monday and Tuesday a series of lows are expected to traverse the
region, aided by a strong jet stream. However, model guidance still
varies widely on timing, location, intensity, and even the number of
lows that could develop and impact us. For now, going with a rainy
solution given the likely warmer temperatures. Capped POPs at 50%
due to the uncertainty surrounding these systems.
&&
.AVIATION /06Z WEDNESDAY THROUGH SUNDAY/...
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High pressure remains in control through this afternoon. A cold
front approaches late tonight and passes through Thursday
morning.
VFR through the day ahead, at least until 00z Thursday, then
increasing chance of MVFR with rain, snow, or a mixture tonight.
Better overall chances of precipitation will be north and east
of city terminals.
Winds WNW at or under 10 kt, lasting through late morning,
before increasing in speed and backing SW in the afternoon with
gusts 20 to 25 kt. SW winds increase further this evening with
gusts toward 30 kt.
...NY Metro (KEWR/KLGA/KJFK/KTEB)TAF Uncertainty...
PROB30s for tonight may be converted to prevailing conditions.
Precip type tonight might be all rain for KJFK/KLGA/KEWR, and
possibly even KTEB as well.
Isolated gusts to 35 kt after 00Z Thu.
OUTLOOK FOR 06Z THURSDAY THROUGH SUNDAY...
Late tonight: Varying conditions across the terminals:
* KSWF: Snow likely with MVFR/IFR cond expected and
accumulation close to an inch.
* KHPN/KTEB: Mixed rain and snow with MVFR.
* KBDR/KEWR/KLGA/KJFK: MVFR with mostly rain, possibly mixed with
snow.
* KISP/KGON: Rain with MVFR with a chance of IFR.
* SW winds G25-30kt at the NYC metros and along the coast.
Thursday: MVFR cond possible with lingering rain/snow showers,
improving to VFR by afternoon except at KGON. W winds G25-30kt
early, increasing to G40kt by late morning.
Thursday night: VFR. WNW winds G35-40kt early, gradually
diminishing to G20-25kt late at night.
Friday: VFR. NW winds G25kt.
Saturday: VFR. W winds G20kt.
Sunday: 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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The shortwave that kicked up winds earlier has moved out to sea.
Thus the winds have subsided some, and will continue to do so
over the remainder of the overnight and prevail below advisory
thresholds.
A clipper system is still on track to pass to our north and bring
strong winds to the area later Wednesday and into Thursday. The
Gale Watches have been converted to Gale Warnings on all
waters. A Small Craft Advisory is in effect for the ocean waters
and eastern Sound for Wednesday afternoon for 25 kt gusts ahead
of the gale conditions. By Wednesday night, gale conditions are
expected on all waters, although more marginal for the NY
Harbor, western Sound and Central Sound. By Thursday, gusts peak
at 40 to 45 kt. Seas also peak Thursday at 12 to 14 feet, with
waves on the central and eastern Sound reaching 5 to 7 feet.
Conditions gradually lower Thursday night to Small Craft
Advisory criteria and then below SCA level by early Saturday.
Sub-SCA conditions are then expected through the start of next
week.
The long duration of offshore winds combined with the strong
offshore winds we are expecting with this system could result in
abnormally low water during the Thursday afternoon and evening low
tides. This is mainly for the NY Harbor and western NY Sound. This
will have to monitored over subsequent forecast cycles, but a Low
Water Advisory may be needed as navigation could be difficult in
shallow waters.-- End Changed Discussion --
&&
.HYDROLOGY...
There are no hydrologic concerns through early next week.
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
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CT...Wind Advisory from 6 AM to 10 PM EST Thursday for CTZ005>012.
NY...Wind Advisory from 6 AM to 10 PM EST Thursday for NYZ067>075-
078>081-176>179.
NJ...Wind Advisory from 6 AM to 10 PM EST Thursday for NJZ002-004-
006-103>108.
MARINE...Gale Warning from 6 PM this evening to 1 AM EST Friday for
ANZ331-335-338-340-345.
Gale Warning from 6 PM this evening to 6 AM EST Friday for
ANZ332-350-353-355.
Small Craft Advisory from 1 PM this afternoon to 6 PM EST this
evening for ANZ350-353-355.-- End Changed Discussion --
&&
$$
SYNOPSIS...BR/JT
NEAR TERM...JE/JT
SHORT TERM...JT
LONG TERM...BR
AVIATION...JC/DR
MARINE...BR/JT
HYDROLOGY...BR/JT