000
FXUS61 KOKX 062115
AFDOKX
Area Forecast Discussion
National Weather Service New York NY
415 PM EST Sat Jan 6 2024
.SYNOPSIS...
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Low pressure will pass south of Long Island tonight, and east of the
region on Sunday. High pressure moves east of the area on Monday.
Low pressure strengthens and passes west of the region Tuesday into
Wednesday. The low will then move northeast and weaken Wednesday
into Thursday. Weak high pressure then returns thereafter through
Friday.-- End Changed Discussion --
&&
.NEAR TERM /THROUGH SUNDAY/...
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Models remain in agreement that low pressure passes to our south
tonight and just NW of the 40N/70W benchmark Sunday morning. Bulk of
the precip will occur through tonight, but PVA aloft interacting
with a surface trough on the backside of the storm brings
additional, but lighter precip during the day Sunday.
Still looks like an all-snow event for a good portion of the
northernmost zones, but not out of the question that as the mid-
levels dry out late tonight a brief period light freezing rain
occurs. A warm nose near 850mb tonight introduces a wintry mix
farther south to the coast. Then between the warm nose and
sufficient boundary layer warmth on an easterly wind off the waters,
mainly rain for LI and NYC metro.
The current forecast has increased snow totals slightly - mainly
away from the immediate coast. Have upgraded Northern New London and
Northern Middlesex Counties to a Winter Storm Warning, with a Winter
Weather Advisory for the southern halves of both counties. The rest
of the headlines remain unchanged.
Winds ramp up tonight with gusts mostly 30-40mph for the coastal
areas. Still looks as if we`ll fall short of advisory criteria, but
there may be a stray gust or two that gets over 45 mph across parts
of eastern Long Island during the overnight hours.
Flooding does not appear to be a factor with this system. For the
locations where precip is expected to be primarily rain, flash flood
guidance combined with expected rainfall amounts and the progressive
nature of the storm should preclude flash flooding/river flooding.
Across parts of NE NJ, it won`t take as much for a chance of
flooding, but at the same time, some of this will be falling in the
form of snow.
Stuck fairly close to the previous forecast regarding temperatures
through the event, which is a little cooler than NBM.-- End Changed Discussion --
&&
.SHORT TERM /SUNDAY NIGHT/...
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Clearing skies due to subsidence and a dry airmass building in.
Gusty NW flow as the low pulls away, especially LI surrounded
by the warm water. Across the interior, fresh snowpack could
allow for decoupling and possibly temps below the NBM fcst.-- End Changed Discussion --
&&
.LONG TERM /MONDAY THROUGH SATURDAY/...
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*Key points*
* A potentially significant storm system will impact the region
Tuesday into Wednesday.
* A period of heavy rain, and river and coastal flooding are all
possible with this system.
* Strong winds with the potential for gusts of 45 to 60 mph, highest
along the coast, Tuesday night into early Wednesday, are also
possible.
Model guidance/ensembles continue to show above-average consistency
in the extended advertising a potent low pressure system to impact
the area midweek. Weak upper ridging on Monday gives way to a
strengthening trough and jet diving south out of the Northern Plains
on Tuesday. This feature heads into the Great Lakes on Wednesday,
and into New England by Thursday. This places the local area on the
eastern side of the system, in the vicinity of the left front quad
of the upper jet Tuesday night into early Wednesday.
At the surface, deepening low pressure Tuesday afternoon induces a
fetch with a connection to the Gulf. Moisture advection commences as
a result into the area, with PWATs nearing 1.25" by Tuesday evening.
This would be close to, or just over, the max PWAT values for OKX
per the SPC sounding climatology. As the surface low heads northeast
into Great Lakes Region by late Tuesday, precipitation will begin to
overspread the area ahead of a warm front. Given the area resides on
the eastern side of the system, am expecting an all rain event. The
one exception may be at the onset across the Lower Hudson Valley,
where residual cold air may allow for some light snow before quickly
changing over. Rain becomes steadier, and heavier, into the Tuesday
overnight as the cold front approaches before finally waning early
on Wednesday. Given the moisture fetch, enhanced forcing from the
upper jet and frontal approach, the ingredients are in place for a
period of heavy rainfall. NBM continues to advertise a widespread 2-
3" event, with highest amounts across northern NJ and the lower
Hudson Valley, where WPC maintains the moderate risk of excessive
presentation. See the hydrology section for additional details.
Then there are the winds associated with the LLJ as the system
approaches. Model soundings continue to show a period of 65-70 kts
at 950mb with a weakly inverted to mostly neutral PBL as the LLJ
approaches after 00Z Wednesday. Have shaved some off of the NBM wind
values given its performance of overpredicting for the past few high
wind events. This yields a widespread 30-40 mph sustained with 45-
60mph gusts, with highest values across the coast.
Weak ridging builds in thereafter for Thursday and Friday.-- End Changed Discussion --
&&
.AVIATION /21Z SATURDAY THROUGH THURSDAY/...
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Low pressure approaches from the south, passing east of Long Island
tonight into Sunday.
MVFR cigs/vsbys late today decline to IFR by early evening, then IFR
or lower overnight into Sunday AM. Gradual improvement to MVFR
through Sunday afternoon.
Precipitation is gradually beginning to fall late this afternoon at
city terminals, and will spread east through the remainder of the
day, initially falling as snow, before mixing with and changing to
rain along the coast this evening. Inland terminals remain snow into
tonight, perhaps mixing or changing to rain at KHPN overnight. A
lull in precipitation is expected overnight before a mix of rain and
snow showers redevelops Sunday morning along the coast, with
additional snow showers inland.
E-ENE winds 10-15 kt increase to around 20 kt along the coast
tonight with gusts 25-30 kt here into early Sun AM. Flow lightens
after 12Z Sun, close to 10 kt, as direction backs northerly, then NW.
NY Metro (KEWR/KLGA/KJFK/KTEB) TAF Uncertainty...
Amendments likely through the TAF period with timing of category
changes and precipitation onset/ending.
OUTLOOK FOR 18Z SUNDAY THROUGH THURSDAY...
Sunday PM: MVFR with lingering RA/SN showers. Becoming VFR at night.
N/NW winds around 10 kt.
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 40-45kt, 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 20-25kt gusting 35-
45kt. Gusts decrease afternoon into the night.
Thursday: VFR. WSW winds 10-15kt.
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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Gales develop tonight on all waters with low pressure approaching,
then passing through or just south of the ocean waters late tonight
into Sunday morning. No changes with this update regarding the
end time of the gale warnings. SCA will likely be needed for the
western waters after the warning expiration Sunday morning.
Same for the eastern waters Sunday afternoon. Sub-advisory
conditions for the non ocean waters starting Sunday afternoon
into evening. Ocean seas will remain elevated, so advisory
conditions prevail Sunday afternoon and night.
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 for a
period early Wednesday. In addition, waves on the ocean waters may
reach 15 to 20 ft. Continued mention of gales and storm force gusts
in the HWO.-- End Changed Discussion --
&&
.HYDROLOGY...
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No hydrologic impacts are expected through Monday.
Thereafter, significant hydrologic impacts are likely. A period
of heavy rainfall Tuesday night into Wednesday will likely
result in flooding across the region. Any total runoff would be
enhanced inland with melted snowfall, especially across the
interior. The Weather Prediction Center has a segment of the
area in a moderate risk for excessive rainfall within parts of
Northeast NJ and expanded the risk further into the Lower Hudson
Valley. The rest of the forecast region in a slight risk for
excessive rainfall. River levels across northeastern NJ and the
Lower Hudson Valley, where the heaviest rainfall is expected to
fall, are expected to rise.-- End Changed Discussion --
&&
.TIDES/COASTAL FLOODING...
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E/NE gales tonight into Sunday morning will produce a surge of
about 2 to 3 ft, resulting in widespread minor coastal flooding
during the morning high tide cycle Sunday. Localized moderate is
a possibility across the south shore back bays of Nassau and
southwest Suffolk counties. Isolated dune erosion expected
during the Sunday morning high tide, overwashes not expected.
There is the chance for a significant coastal flood event 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. Early guidance from Steven`s
NYHOPS ensemble is producing surge values of 3 to 4 ft. This
will also coincide with increasing astronomical tides with a new
moon on Jan 11. Along the oceanfront, potential for 15-20 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.-- End Changed Discussion --
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
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CT...Winter Storm Warning until 6 PM EST Sunday for CTZ005-006.
Winter Storm Warning until 6 PM EST Sunday for CTZ007-008.
Winter Weather Advisory until 11 AM EST Sunday for CTZ009.
Coastal Flood Advisory from 4 AM to 10 AM EST Sunday for
CTZ009>012.
Winter Weather Advisory until 6 PM EST Sunday for CTZ010>012.
NY...Winter Storm Warning until 6 PM EST Sunday for NYZ067>070.
Winter Weather Advisory until 11 AM EST Sunday for NYZ071.
Coastal Flood Advisory from 4 AM to 10 AM EST Sunday for
NYZ071-078-177.
Coastal Flood Advisory from 2 AM to 11 AM EST Sunday for
NYZ079-081.
Coastal Flood Advisory from 1 AM to 10 AM EST Sunday for
NYZ080-179.
NJ...Winter Storm Warning until 6 PM EST Sunday for NJZ002-103.
Winter Weather Advisory until 11 AM EST Sunday for NJZ004-104-
105-107.
MARINE...Gale Warning until noon EST Sunday for ANZ331-332-340-345-350-
353.
Gale Warning until 5 AM EST Sunday for ANZ335-338-355.-- End Changed Discussion --
&&
$$
SYNOPSIS...JC/DBR
NEAR TERM...JC
SHORT TERM...JC
LONG TERM...DBR
AVIATION...DR
MARINE...JC/DBR
HYDROLOGY...JC/DBR
TIDES/COASTAL FLOODING...DW