000
FXUS61 KOKX 060254
AFDOKX
Area Forecast Discussion
National Weather Service New York NY
954 PM EST Fri Jan 5 2024
.SYNOPSIS...
High pressure builds in from the southwest tonight and then passes
offshore in the morning. Deepening low pressure approaches from
the southern states on Saturday, passing to the south and east
Saturday night into Sunday. High pressure builds in on Monday and
stays in control through early Tuesday. A strong low pressure
system will track to our west and impact the area late Tuesday
through Wednesday. High pressure then slowly builds in from the
south on Thursday.
&&
.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
-- Changed Discussion --
Only minor changes needed with this updated. Previous discussion
follows.
Ridging both aloft and at the surface builds east tonight and
across the area. There will be some high level clouds increasing
overnight ahead of the next system, especially toward daybreak.
Thus, with the combination of mainly clear skies and
diminishing winds, leaned toward a blend of the colder MET/MAV
MOS (versus NBM). Lows are forecast to range from the upper
teens to around 20 inland, to the lower and mid 20s most other
locations, except 25 to 30 NYC/NJ metro.-- End Changed Discussion --
&&
.SHORT TERM /6 AM SATURDAY MORNING THROUGH SUNDAY/...
For the last several days, models have been forecasting low
pressure to move out of the southeast U.S. on Saturday, passing
to the south and east of the area Saturday night into Sunday.
Changes with the latest set of guidance have been generally
minor with subtle shifts in the low track. The trend has been
for a slightly farther track to the north over the last 24h.
With retreating high pressure across eastern Canada and strong
easterly flow developing late Saturday, coastal locations will
see a warming boundary layer, and eventually a warm nose aloft
in the southerly flow. Airmass is very marginal for a period of
snow at the coast, but inland a different story with the bulk
of the liquid falling as snow. Liquid equivalents for this event
are generally 0.7 to 1.0", highest across interior NE NJ.
The heaviest precipitation will occur on the front end of the
system Saturday evening, courtesy of deep-layered lift. The
primary lifting mechanisms include an upper jet working in from
the south and strong 85-70h frontogenetic. In fact, should this
precipitation move in earlier than currently forecast, coastal
locations could see a burst of moderate/heavy snow, especially
for western LI and the NYC/NJ metro. These areas have the
potential for 1 to 3 inches. The SW CT coast looks cold enough
to support advisory level snow of 2 to 4 inches. For interior
NE NJ, the Lower Hudson Valley, and interior SW CT, looking for
anywhere from 5 to 10 inches, highest across western portions of
Orange County NY. These locations have all been updated to a
winter storm warning. For interior sections of SE CT, confidence
is a bit lower to reach warning level criteria (6") due to a
warming boundary layer in a strong easterly flow off the
Atlantic. So for the time, will stay with a watch for this area.
Once gain, much of the heavy precipitation will be on the front
end, should this occur even earlier, it`s possible totals will
be increased at the coast; vice versa, lower totals if the
onset is delayed. As the mid levels dry out, the second half of
the night will feature light rain/drizzle at the coast, with
snow possibly mixed with rain and/or drizzle inland.
East winds will ramp up late Saturday afternoon/early evening,
15 to 25 mph, with gusts up to 35 mph, highest at the coast.
As the low pulls out to the east on Sunday, there will likely
be some light precipitation that goes back to snow even at the
coast, but with temperatures above freezing, any accumulations
would be minor. Winds will back around to the N/NE Sunday on
the backside of the low, with gusts dropping off to around 20
mph.
&&
.LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/...
*Key Points*
* A strong low pressure system will impact the area late Tuesday
through Wednesday, with wind and flooding impacts likely.
Quiet weather is expected Monday and Monday night as high pressure
shifts through the area.
Main focus then turns to a strong low pressure system that will
bring strong winds and flooding impacts to the region. Deterministic
and ensemble guidance continues to be in great agreement with little
change from run to run over the past several days. This is leading
to unusually higher than normal forecast confidence this far out.
A shortwave trough will enter the northwest CONUS Saturday morning
and dig down to the Southern Plains before closing off and lifting
northeast. The associated surface low will track west of our area,
with all of the latest deterministic guidance showing a sub 980mb
low by the time it reaches the Great Lakes. This will place the area
under a very tight pressure gradient as a ~1030mb high will be
departing to our east. Confidence continues to increase in strong
winds, with the potential for damaging winds (mainly across Long
Island and the southeast CT coast). The heavy rain is the other
hazard as flooding impacts are expected (see hydrology section
below). This storm will bring mainly plain rain to the area.
However, with cold air in place across the interior, a wintry mix is
possible at the start of the event. This includes the potential for
a brief period of freezing rain as warm air moves in aloft, but the
surface remains cold, before warm air take over the entire area.
Confidence of the freezing rain remains low at this point and this
will also depend on timing of precip moving in. Will continue to
keep this out of the forecast for now. By Tuesday night,
temperatures warm for the entire region to see plain rain, and most
of this rainfall will be moderate to heavy in nature.
Most of the heavy rain comes to an end Wednesday morning, with any
leftover showers ending Wednesday afternoon. High pressure then
starts to build back into the region on Thursday.
A weak shortwave passes north of the region on Friday. This could
set of a few showers across area. Will keep just some chance POPs in
the forecast for now.
&&
.AVIATION /03Z SATURDAY THROUGH WEDNESDAY/...
-- Changed Discussion --
VFR through early Saturday afternoon as high pressure over the
region slides off the Mid Atlantic coast tonight. Low pressure
approaches from the southwest Saturday morning. There is a low
chance of MVFR developing toward 18Z along the coast, depending on
the timing of the low and how quickly the precipitation moves
into the area. Have a PROB 30 for the potential for snow to move
in from 18Z-20Z Saturday for the metro terminals, so MVFR or
lower is possible during this time frame. However, MVFR
conditions are more likely after 20Z, with a period of moderate
snow possible for the metro terminals until 00Z Sunday. This
will lead to LIFR conditions before the change over to a mix of
rain and snow, then all rain after 00Z. KTEB may remain a mix of
rain and snow through the TAF period, while KSWF will likely
remain all snow. Precipitation will come in from southwest and
track northeast, so deteriorating conditions are expected to
follow this trend, with eastern terminals not seeing MVFR or
lower until late Saturday afternoon into the evening hours
(KGON).
W to NW flow 10 kt or less becomes light and variable this
evening and overnight. East to NE winds develop Saturday
morning and increase, especially during the afternoon. Easterly
winds of 10 to 20 kt are expected by mid to late afternoon with
gusts of 20 to 30 kt. Isolated gusts of 35 kt are possible,
especially along coastal terminals, such as KJFK, KLGA, KISP,
KBDR, and KGON.
NY Metro (KEWR/KLGA/KJFK/KTEB) TAF Uncertainty...
No unscheduled amendments expected overnight into Saturday
morning. Amendments expected by Saturday afternoon with snow
moving into the region, potentially rapidly bringing conditions
to LIFR.
OUTLOOK FOR 00Z SUNDAY THROUGH WEDNESDAY...
Saturday Night: IFR or lower. Snow inland and rain/snow near
the coast, becoming all rain. E/NE winds 15-20kt gusting
25-35kt.
Sunday: IFR or lower with snow inland and rain/snow near the coast.
NYC metro and coast may end as snow late in the afternoon. Becoming
VFR late. NW winds becoming N 10-15kt, gusting 20-30kt, diminishing
during the afternoon.
Monday: VFR.
Tuesday: VFR early becoming MVFR or lower. Rain during the
afternoon. E winds 15-20kt with gusts 25-30kt in the afternoon. SE
winds increasing Tuesday night to 25-35kt, gusting 35-45kt, highest
winds along the coast. LLWS likely at night.
Wednesday: MVFR or lower with rain in the morning. Rain ending
late in the day with conditions improving. S SW wind 25-35kt
gusting 30-35kt.
Detailed information, including hourly TAF wind component forecasts,
can be found at: https:/www.weather.gov/zny/n90-- End Changed Discussion --
&&
.MARINE...
Gales warning have been issued for all waters for late Saturday
afternoon and night due to easterly winds ramping up ahead of a
deepening coastal low. Gusts of 35 to 40 kt can be expected
with seas building to 7 to 10 ft on the ocean, and 4 to 8 ft
across portions of LI sound. Winds will then back around to the
N/NE Sunday and gradually diminish. Seas will remain high on
the ocean waters.
Lingering 5 to 6 ft waves are expected on the ocean waters on
Monday. Otherwise, quiet conditions on the waters expected until
late Tuesday. Strong low pressure will then track to the west and
impact the area through Wednesday. Gale force wind gusts look likely
on all waters, as well as the potential for storm force gusts. Waves
on the ocean waters look to reach 15 to 20 ft. Continued mention of
gales and storm force gusts in the HWO.
&&
.HYDROLOGY...
Significant hydrologic impacts, including river flooding, are
likely late Tuesday into Wednesday as strong low pressure passes
west of the area. The NBM currently has a 70 to 90% chance
across much of the area for seeing 2 inches in 24 hours and a 50
to 70% chance of 3 inches. This would be on top of whatever
snow pack there is from this weekend`s storm. The Weather
Prediction Center has placed much of the area in a Day 5 "slight
risk" and a portion of NE NJ and the Lower Hudson Valley in a
"Moderate risk" for excessive rainfall.
&&
.TIDES/COASTAL FLOODING...
Gale force E/NE winds Saturday Night into Sunday morning will
build surge. Widespread minor coastal flooding expected along
the southern and eastern bays of LI and LI Sound with the
Sunday morning high tide. Elsewhere potential for localized
minor coastal flooding along NY/NJ harbor, Jamaica Bay, and NYC
coast along W LIS. Isolated dune erosion expected during the
Sunday morning high tide, overwashes not expected.
More significant coastal flood threat with the Wed AM high
tide. Potential for SE gale to storm force winds Tuesday Night,
bringing potential for widespread moderate to locally major
coastal flooding wit the Wed AM high tide. Along the
oceanfront, potential for 14-19 ft surf causing widespread dune
erosion and scattered overwashes. Localized dune
inundation/breaches possible where dunes have been compromised
by earlier storm events. More details on this event early next
week.
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
CT...Winter Storm Warning from 4 PM Saturday to 6 PM EST Sunday for
CTZ005-006.
Winter Storm Watch from Saturday evening through Sunday
afternoon for CTZ007-008.
Winter Weather Advisory from 4 PM Saturday to 11 AM EST Sunday
for CTZ009-010.
Coastal Flood Advisory from 5 AM to 10 AM EST Sunday for
CTZ009>012.
NY...Winter Storm Warning from 4 PM Saturday to 6 PM EST Sunday for
NYZ067>070.
Winter Weather Advisory from 4 PM Saturday to 11 AM EST Sunday
for NYZ071.
Coastal Flood Advisory from 5 AM to 10 AM EST Sunday for
NYZ071-078-177.
Coastal Flood Advisory from 2 AM to 10 AM EST Sunday for
NYZ079>081-179.
NJ...Winter Storm Warning from 4 PM Saturday to 6 PM EST Sunday for
NJZ002-103.
Winter Weather Advisory from 4 PM Saturday to 11 AM EST Sunday
for NJZ004-104-105-107.
MARINE...Gale Warning from 5 PM Saturday to 5 AM EST Sunday for ANZ331-
332-335-338-340-345-350-353-355.
&&
$$
SYNOPSIS...BC/DW
NEAR TERM...BC/DW
SHORT TERM...DW
LONG TERM...BC
AVIATION...JP
MARINE...BC/DW
HYDROLOGY...BC/DW
TIDES/COASTAL FLOODING...