486
FXUS61 KOKX 032050
AFDOKX
Area Forecast Discussion
National Weather Service New York NY
350 PM EST Tue Dec 3 2024
.SYNOPSIS...
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High pressure over the Tennessee Valley will remain in control
through tonight 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 WEDNESDAY MORNING/...
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Similar conditions currently as the past few days. Some sprinkles
and flurries have been observed across the area and that may
continue through this evening. Some areas across the interior
may see some light snow showers with the activity moving in
from the north.
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 WEDNESDAY MORNING THROUGH THURSDAY NIGHT/...
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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.-- End Changed Discussion --
&&
.LONG TERM /FRIDAY THROUGH TUESDAY/...
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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.-- End Changed Discussion --
&&
.AVIATION /21Z TUESDAY THROUGH SUNDAY/...
VFR as high pressure building into the Tennessee Valley remains
in control through Wednesday morning.
VFR with NW winds either side of 10 kt, except more out of the W
at KEWR. Winds did gust to 20 kt at some terminals right around
18Z, but this potential should only be sporadic at most through
21Z.
Winds should stay up into at least part of the evening push,
then diminish late this evening and overnight, and become W-SW
late tonight into Wed morning. Winds should back a little more
southerly by afternoon, with some gusts up to 20 kt at the NYC
metros.
...NY Metro (KEWR/KLGA/KJFK/KTEB)TAF Uncertainty...
Sporadic gusts 15-20 kt possible before 21Z.
OUTLOOK FOR 18Z WEDNESDAY THROUGH SUNDAY...
Wednesday afternoon: VFR. S-SW winds G20kt.
Wednesday night: Varying conditions across the terminals:
* KSWF: Snow likely with IFR cond expected and accumulation
close to an inch.
* KHPN/KTEB/KEWR: Snow likely early in the evening with IFR
possible but little/no accumulation, then rain/snow likely
with MVFR.
* Elsewhere: MVFR cond expected, with chance of rain/snow at
the NYC metros/KBDR and rain farther east.
* SW winds G20-25kt 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 afternoon.
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
&&
.MARINE...
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A clipper system is still on track to pass to our north and bring
strong winds to the area. 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...
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There are no hydrologic concerns through early next week.-- End Changed Discussion --
&&
.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 Wednesday to 1 AM EST Friday for ANZ331-
335-338-340-345.
Gale Warning from 6 PM Wednesday to 6 AM EST Friday for ANZ332-
350-353-355.
Small Craft Advisory from 1 PM to 6 PM EST Wednesday for
ANZ350-353-355.-- End Changed Discussion --
&&
$$
SYNOPSIS...BR/JT
NEAR TERM...JT
SHORT TERM...JT
LONG TERM...BR
AVIATION...BG
MARINE...BR/JT
HYDROLOGY...BR/JT