000
FXUS61 KOKX 082041
AFDOKX
Area Forecast Discussion
National Weather Service New York NY
341 PM EST Fri Dec 8 2023
.SYNOPSIS...
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High pressure will slowly move offshore tonight through Saturday. At
the same time, a warm front will stalled in the area and head
northeast on Saturday.-- End Changed Discussion --
&&
.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
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Upper level ride will move over the Northeast tonight as the center
of surface high pressure slides off the East Coast. The main
forecast challenges tonight will be if there will be any fog and/or
stratus developing late tonight. NAM forecast soundings show a low
level inversion late tonight well inland with abundant low level
moisture trapped underneath. Other models show a hint of this
inversion, but not nearly as deep. Meanwhile, ensembles show high
probabilities of fog and stratus, mainly well the aforementioned
well inland areas. Therefore, opted to continue mention of patchy
fog and increasing clouds late. This will mean that temperatures in
these areas will likely drop fairly quickly once sun sets tonight,
but then remain steady and then slowly increase through the rest of
the night, mainly sometime after 3 am. There is also the possibility
of freezing fog in the areas well north of the area, but with even
more uncertainty, did not mention in the actual forecast. If this
does occur, then an SPS may need to be issued later tonight.-- End Changed Discussion --
&&
.SHORT TERM /6 AM SATURDAY MORNING THROUGH SATURDAY NIGHT/...
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Any fog burns off early in the morning Saturday as the lower layers
warm. Weak warm advection and rising heights will mean warmer
conditions, with highs rising into the 50s region-wide. More in the
way of clouds are expected as a weak surface trough moves toward the
area, but if clouds break out a bit, even warmer temperatures are
possible. Saturday night will see a slight chance to low end chance
for light rain with the warm front still in the forecast area. The
only areas the might not see any precipitation will be eastern
areas. With continued abundant low level moisture, patchy fog will
once again be possible, though a bit more widespread than the
previous night. Lows will also be warmer given continued weak warm
air advection, ranging from the 30s well inland to the middle 40s
across the metro area.-- End Changed Discussion --
&&
.LONG TERM /SUNDAY THROUGH FRIDAY/...
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This section will be updated shortly. Previous discussion
follows:
A 500mb trough digs in to our west on Sunday, then lifts during the
day Monday with its axis shifting through the forecast area Monday
evening. At the surface, a strong cold front approaches us on Sunday
and passes through during Sunday night. While it`s passing through,
an area of low pressure develops along the front in Tennessee or the
Middle Appalachians and passes to our north as is further develops
and strengthens.
Rain chances ramp up through the day with the entire forecast area
likely seeing rain by the end of the afternoon. The rain could be
heavy at times mainly during Sunday night as a strong low level jet
develops over us and combines with deep synoptic lift aloft and an
anomalously moist air mass. Some models continue to show some
elevated instability, so with deep lift, will keep in an isolated
thunderstorm in the forecast. Rain chances continue into Monday even
behind the front as the flow aloft remains cyclonic and we`ll be
within the right entrance region of an upper jet streak. Should
precipitation actually occur Monday morning over the higher
elevations well NW of the city, some snowflakes may mix in with
showers. 1.5-2.5" of rainfall is expected Sunday afternoon through
Monday morning. The heaviest rainfall is most likely to occur during
Sunday night. Minor urban/small stream flooding will be possible,
mainly Sunday night - confidence in this is moderate. Cannot
completely rule out flash flooding either, but this is a lower
confidence forecast as chances are low given flash flood guidance
and the progressive nature of the storm system.
Regarding winds for this event, 925mb winds continue to be progged
to reach 60-80kt over roughly the eastern half of the forecast area
Sunday night. Even if a relatively stronger low level inversion were
to be in place during the time that the LLJ moves through, about
half of that speed could potentially reach the surface. The hourly
NBM probabilities for wind gusts greater than 54 mph are at about a
50-80% chance of occurring for the immediate coastlines on Long
Island and southeast Connecticut. These chances are less than 20%
for Manhattan, NE NJ, the lower Hudson Valley and SW CT. Parts of
Queens and Brooklyn are around 20-30% chance of this occurring. Peak
wind gusts may reach wind advisory criteria for some areas along the
coast east of Manhattan given the setup and potential help from heavy
downpours. The current forecast has gusts 40-45mph for coastal areas
and 30-40mph for most inland areas during Sunday night. I used the
NBM 10th percentile for winds in this forecast. The NBM
deterministic seemed too high, but given the last few runs of most
available guidance, they all show gusts at or above this current
forecast (with the exception of the GDPS and RDPS). When this event
falls into the timeframe of some CAMs this will really help in
determining how much of the LLJ will mix down to the surface.
High pressure then builds in through the rest of Monday and remains
in control through Thursday with an extended period of dry weather
and highs generally in the 40s.-- End Changed Discussion --
&&
.AVIATION /21Z FRIDAY THROUGH WEDNESDAY/...
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High pressure will slowly move offshore through Saturday.
Mainly VFR conditions are forecast through the TAF period. The only
exception is the potential for MVFR to IFR fog late tonight into
early Saturday morning, mainly for KSWF and KHPN.
Light flow is forecast through the TAF period with wind speeds below
10 kt. S-SE winds into early this evening become light and/or
variable tonight. Wind gradually become SE again late Saturday
morning into the afternoon.
...NY Metro(KEWR/KLGA/KJFK/KTEB) TAF Uncertainty...
MVFR visibilities possible early Saturday morning.
OUTLOOK FOR 18Z SATURDAY THROUGH WEDNESDAY...
Saturday Afternoon-Night: VFR.
Sunday: MVFR or lower in developing showers from west to east
through the day. S winds 15-20 kt with gusts 25-30 kt in the
afternoon.
Sunday Night: IFR in showers. Isolated thunderstorms possible. S
winds 15-25 kt with gusts 25-40 kt, strongest near the coast. A few
gusts up to 55 kt possible near the coast.
Monday: MVFR or lower early in showers, then VFR. S-SW wind gusts 30-
40 kt eastern Long Island and Southeast Connecticut early.
Otherwise, W-WNW 15-20 kt with gusts 25-35 kt.
Tuesday: VFR. SW gusts 15-20 kt in the afternoon.
Wednesday: VFR. W gusts 15-20 kt in the afternoon.
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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Conditions are expected to remain below SCA criteria from tonight
through Saturday night as a weak pressure gradient remains in
place.
The long term section will be updated shortly. Previous
discussion follows:
Winds and seas should ramp up quickly during Sunday with small craft
conditions quickly going to gales in all likelihood by late in the
day/early evening. Solid gales are expected across all waters Sunday
night, with gales likely lingering into Monday morning for most of
the waters. Gales may continue well in the afternoon on the ocean.
Storm Watch conditions are possible on the eastern ocean waters
based on the new forecast, but confidence in this remains low at
this time. Ocean seas are likely build to 10-15 feet during this
time with waves over 5 ft possible across portions of eastern Long
Island Sound. SCA conds on the ocean for Tuesday as seas remain
elevated.-- End Changed Discussion --
&&
.HYDROLOGY...
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There are no hydrologic concerns through Saturday night.
The long term section will be updated shortly. Previous
discussion follows:
1.50 to 2.50 inches of rain are expected from Sunday afternoon
through Monday morning. The heaviest rainfall is most likely to
occur during Sunday night. Minor urban/small stream flooding
will be possible, mainly Sunday night - confidence in this is
moderate. Cannot completely rule out flash flooding either, but
this is a lower confidence forecast as chances are low given
flash flood guidance and the progressive nature of the storm
system.-- End Changed Discussion --
&&
.TIDES/COASTAL FLOODING...
A strong cold front will bring increasing southerly flow late
Sunday into Sunday night. The system brings potential for minor
coastal flooding with the Monday morning high tide cycle.
However, the strongest southerly flow is most likely to occur
between high tide cycles. Winds will quickly shift to the west
early Monday morning, which will help keep water levels down
during times of high tide.
There remains a large amount of spread in the surge guidance.
The highest chance for minor coastal flooding at this time
appears to be for the south shore back bays and over the western
Long Island Sound along the Westchester and Fairfield coasts.
If the higher end of the surge guidance and stronger onshore
winds linger closer to high tide, then minor coastal flooding
would be more widespread, and a localized moderate coastal
flooding threat would exist.
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
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CT...Flood Watch from Sunday afternoon through late Sunday night
for CTZ005>012.
NY...Flood Watch from Sunday afternoon through late Sunday night
for NYZ067>075-078-080-176>179.
High Wind Watch from Sunday afternoon through late Sunday
night for NYZ075-078>081-176>179.
NJ...Flood Watch from Sunday afternoon through late Sunday night
for NJZ002-004-006-103>108.
MARINE...Gale Watch from Sunday afternoon through late Sunday night for
ANZ331-335-338.
Storm Watch from Sunday afternoon through late Sunday night
for ANZ332-340-345-350-353-355.-- End Changed Discussion --
&&
$$
SYNOPSIS...JMC/JP
NEAR TERM...JP
SHORT TERM...JP
LONG TERM...JMC
AVIATION...DS
MARINE...JMC/JP
HYDROLOGY...JMC/JP
TIDES/COASTAL FLOODING...