000
FXUS61 KOKX 122117
AFDOKX
Area Forecast Discussion
National Weather Service New York NY
417 PM EST Fri Jan 12 2024
.SYNOPSIS...
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Another deepening low will pass across the eastern Great Lakes
tonight into Saturday, sending a strong frontal system through
the area during this time. An arctic frontal passage occurs on
Sunday. Low pressure may produce some snow by the middle of
next week.-- End Changed Discussion --
&&
.NEAR TERM /THROUGH SATURDAY/...
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As deepening low pressure tracks across the Great Lakes tonight
into Saturday, it will send a strong frontal system across the
the area. A strong LLJ (70-080kt) works up the eastern seaboard
tonight sending the warm front northward, preceded by strong
thermal forcing and some elevated instability. Rain will
overspread the area from SW to NE, from late this evening into
the early morning hours Saturday. While this will be a fast
moving system with much of the rain exiting far eastern LI/SE
CT shortly after daybreak, it will bring a 6hr period of moderate
to occasionally heavy rain. Due to the recent stretch of rainfall
events starting back in mid December, streamflows remain high
and grounds are saturated. FFG values are extremely low across
NE NJ (under an inch), and while higher elsewhere, it will not
take long for faster responding river and streams to reach or
exceed bank full. Thus, a Flood Watch remains up across NE NJ,
portions of the Lower Hudson Valley (Rockland and Westchester),
and all of southern CT. In addition, a strong SE flow will
enhance rainfall across this area due to upslope flow. The watch
area can expect 1.5 to 2.5 inches with localized amounts up to
around 3 inches. Elsewhere, generally looking for around an
inch. An isolated thunderstorm is also a possibility during this
time with rainfall rates possibly encroaching an inch an hour.
PWATs are anomalously high at 1.15 to 1.30".
A Wind Advisory remains up for LI, NYC/NJ metro, southern
Westchester, and coastal/interior SE CT. Winds are not quite as
strong in the mixed layer as the past event. The LLJ moves into
the area after midnight and will also strengthen the low-level
inversion and inhibit higher winds from getting to the surface.
The one caveat here could be thunderstorms, but low-levels
will be stabilizing, likely limiting the wind energy getting to
the surface. Expecting wind gusts along the coast up to 50 mph,
with inland areas 35 to 45 mph. An few higher gusts are
possible. The period of strongest winds will coincide with the
heaviest rain.
Temperatures will drop initially to their lows early this
evening, but then steadily rise overnight. By morning, most of
the area will be into the 50s.
The associated cold front moves through in the morning, ending
the heavy rain threat with perhaps a few lingering showers.
Winds will veer around to the WSW with perhaps a brief lull in
the morning before cold advection and deep mixing produces gusts
up to 40 mph during the late morning and afternoon hours. Highs
will in the 50s will occur in the morning, then steadily fall
into the upper 30s and lower 40s by early evening. Expect
clearing during this time, however, with cyclonic flow and the
upper trough working into the region, intervals of clouds and
sprinkles will be possible in the afternoon, especially north
and west of NYC.-- End Changed Discussion --
&&
.SHORT TERM /SATURDAY NIGHT/...
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Gusty west winds will be slow to come down Saturday night. Lows
will return closer to seasonable levels in the upper 20s to
lower 30s. A few flurries are possible well north and west.-- End Changed Discussion --
&&
.LONG TERM /SUNDAY THROUGH FRIDAY/...
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The modeling is in pretty good agreement that an arctic front
passes on Sun. This will set up a colder regime for the area
thru the rest of the fcst period. With the front itself,
although it is fairly moisture starved, there will be strong
dpva with the shrtwv and adiabatic llvl lapse rates. As a
result, went abv the NBM model guidance and included sct shwrs.
Initially for most of the area, perhaps a few drops of rain,
then the cold air comes in and most of the shwrs should be in
the form of snow. The snow squall parameter is non-zero.
Otherwise, windy for the rest of Sun and Sun ngt. Time heights
suggest gusts around 30kt on during the day, then lessening
overnight. Went with the NBM for temps with local adjustments. Wind
chills Sun ngt in the single digits and teens.
High pres ridges across the area on Mon. Dry wx with temps in the
20s and low 30s per the NBM guidance.
The models have been suggesting that the trof over the ern portion
of the country will allow low pres to develop over the Atlc and
potentially produce snow locally. The 12Z runs continue to support
this. It is too far out to hang your hat on any one soln, but likely
pops for snow on Tue per the blended approach were accepted and used
in the fcst. Based on the 12Z deterministic ECMWF and GFS, did keep
things all snow over land, and went with the colder NBM50 for Tue
which was close to the MEX. There remains the possibility that if a
low does track close enough to the coast, mixing or a changeover
could occur in some areas.
The fcst tapers pops off on Wed, but the overall timing of the sys
could slow and be Tue ngt into Wed. The GFS suggests this
possibility, but it doesn`t look like the NBM probs have caught up
yet.
High pres and dry on Thu, then another low may take shape for Fri.
The EPS had a much stronger signal than the GEFS. NBM pops were
about 30 to 40 percent, and went with that.-- End Changed Discussion --
&&
.AVIATION /20Z FRIDAY THROUGH WEDNESDAY/...
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Low pressure approaches from the west, impacting the terminals
tonight into Saturday.
VFR through this afternoon with MVFR cigs quickly developing around
03Z Saturday as rain moves in. IFR, potentially briefly lower,
overnight tonight into Saturday morning. PROB30 remains for
thunderstorms late tonight.
E/SE around 10kt this afternoon increase this evening to 20-25kt
late tonight with gusts developing toward 00Z Saturday. Gusts may be
as high as 45kt for a brief period 05Z to 10Z, especially along the
coast. LLWS develops around 05Z through 12Z with 2Kft winds up to
65kt, and possibly 70kt along the coast. Winds become SW Saturday
morning. There will be a brief lull in the early morning and then
late morning into the afternoon gusts will come back up to mainly 30-
35kt, with potential for an isolated 40kt gust.
...NY Metro (KEWR/KLGA/KJFK/KTEB) TAF Uncertainty...
Amendments tonight into Saturday morning for changing categories.
Isolated 40-45 kt gusts possible 05Z to 10Z, especially at KJFK.
After a lull period in winds early Saturday morning, potential for
an isolated 40kt gust Saturday afternoon.
OUTLOOK FOR 18Z SATURDAY THROUGH WEDNESDAY...
Saturday Afternoon: VFR. SW 20-30kt G30-35kt, isolated 40kt gust
possible.
Sunday: Mainly VFR, chance of MVFR with a slight chance of snow
showers or flurries during the afternoon. W 15-25kt G30-35kt,
isolated 40kt gust.
Monday: VFR.
Tuesday: MVFR or lower possible with a chance of snow.
Wednesday: VFR. W-NW gusts 25 to 30kt.
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 are up on all waters for tonight as SE winds ramp up to
25-35 kt with gusts 40 to 45 kt after midnight, highest on the
ocean waters. A brief gust up to 50 kt possible late on the
ocean, but duration does not warrant a storm warning.
Behind the system, a westerly gale is likely Sat into Sat night,
especially for the ocean and the eastern Sound/bays.
Gales are again possible on Sun. Winds decrease Sun ngt, with
all areas likely blw sca criteria Mon and most of Tue. A sca may
be needed, especially on the ocean, Wed and possibly Thu with
low pres over the Atlc.-- End Changed Discussion --
&&
.HYDROLOGY...
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Hydrologic impacts are likely late tonight into Saturday. WPC
continues a slight risk of excessive rainfall, due to another
round of moderate to heavy rain. 1 to 2.5 inches of rainfall is
currently forecast, with locally higher amounts possible. The
heaviest rain is forecast to be across interior southern CT due
to orographic enhancement from a strong SE flow. With rivers
and streams running high from previous rainfall, widespread
minor to moderate river flooding looks likely along the fast-
responding rivers and streams in NE NJ, the Lower Hudson Valley,
and southern CT.
There are no hydrologic concerns Saturday night through Thursday
at this time. It is too early to talk specific snowfall amounts
with the potential coastal low early to mid next week.-- End Changed Discussion --
&&
.TIDES/COASTAL FLOODING...
Widespread minor to moderate with areas of major coastal flood
potential continues to increase for the Saturday morning high
tide as SE gales build surge to 3-4 ft Fri night, with a wind
shift to SW gales Saturday morning near the time of high tide.
Timing of wind shift will be an important factor for the
magnitude of surge. This scenario, like the Tue night and Dec
18th events, is conducive to water piling up in the Great South
Bay during strongest wind forcing, inhibited from drainage thru
inlets as tide comes in and accompanied by high wave action,
and then shifting this elevated water to the east side of the
bay with the wind shift. Potential for widespread major exits
here. Major flood thresholds looks to be a reasonable worst case
scenario for Jamaica Bay. Elsewhere, widespread minor to locally
moderate flooding is expected.
Along the oceanfront, breaking surf height should be lower than
the last couple of events, but 12-16 ft breaking surf with
similarly elevated water levels, impacting compromised dune
structure will likely result in another round of widespread
dune erosion and scattered overwashes. Localized breaches
possible where dunes have been severely compromised and barrier
beaches are narrow.
Forecast details will be refined over the next 24 hrs.
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
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CT...Flood Watch from 10 PM EST this evening through Saturday
morning for CTZ005>012.
Wind Advisory from 10 PM this evening to 6 AM EST Saturday for
CTZ008>011.
Coastal Flood Warning from 9 AM to 3 PM EST Saturday for
CTZ009-010.
Coastal Flood Warning from 7 AM to 2 PM EST Saturday for
CTZ011-012.
Wind Advisory from 10 PM this evening to 9 AM EST Saturday for
CTZ012.
NY...Flood Watch from 10 PM EST this evening through Saturday
morning for NYZ069>071.
Wind Advisory from 10 PM this evening to 6 AM EST Saturday for
NYZ071>075-078-080-176>179.
Coastal Flood Warning from 7 AM to 2 PM EST Saturday for
NYZ178.
Wind Advisory from 10 PM this evening to 9 AM EST Saturday for
NYZ079-081.
Coastal Flood Advisory from 7 AM to 2 PM EST Saturday for
NYZ072-074-075.
Coastal Flood Advisory from 9 AM to 3 PM EST Saturday for
NYZ071-073-078-176-177.
Coastal Flood Warning from 7 AM to 6 PM EST Saturday for
NYZ079>081-179.
NJ...Flood Watch from 10 PM EST this evening through Saturday
morning for NJZ002-004-006-103>108.
Wind Advisory from 10 PM this evening to 6 AM EST Saturday for
NJZ006-106-108.
Coastal Flood Advisory from 7 AM to 2 PM EST Saturday for
NJZ006-104-106-108.
MARINE...Gale Warning until 6 AM EST Sunday for ANZ331-332-335-338-340-
345-350-353-355.-- End Changed Discussion --
&&
$$
SYNOPSIS...JMC/DW
NEAR TERM...DW
SHORT TERM...DW
LONG TERM...JMC
AVIATION...JT
MARINE...JMC/DW
HYDROLOGY...JMC/DW
TIDES/COASTAL FLOODING...