000
FXUS61 KOKX 242033
AFDOKX
Area Forecast Discussion
National Weather Service New York NY
333 PM EST Fri Nov 24 2023
.SYNOPSIS...
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High pressure builds over the northeast through Saturday and then
offshore Saturday night into Sunday. Low pressure develops along the
Middle Atlantic coast late Sunday and impacts the region Sunday
night into early Monday. High pressure gradually builds back in
through the middle of next week, and weakens late in the week
as low pressure passes to the north. High pressure slowly builds
back on Friday.-- End Changed Discussion --
&&
.NEAR TERM /THROUGH SATURDAY/...
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A cold front has moved offshore with cold advection increasing
through this evening. Temperatures and dew points will start
falling this evening under a strengthening NW flow. NW winds
10-15 mph with gusts 20-25 mph are expected the first half of
tonight, strongest near the coast. These winds are a result of a
tightening pressure gradient ahead of sprawling high pressure
building towards the northeast from the Northern Plains and
Great Lakes. The pressure gradient weakens considerably early
Saturday morning allowing winds to diminish. The core of the
arctic air will remain to our north, but there will be enough
low level cold air to bring our coldest night of Fall 2023. Lows
should fall into the lower and middle 20s inland and middle and
upper 20s most elsewhere. The NYC metro will see its first
widespread freeze with temperatures falling to near 30 degrees.
Wind chills the first half of the night will fall into the 20s
and low 30s before settling closer to air temperatures as winds
weaken.
High pressure will be will remain over the area on Saturday as
a progressive ridge builds over the northeast. There may be
some high clouds from time to time, but mostly sunny conditions
are forecast. Highs will only rise into the upper 30s and lower
40s, more typical of the end of December and early January.
Winds will be weak due to the high overhead, so wind chills will
be close to actual air temperatures. Have also gone with the
lower dew points in MOS given that the the NBM/model consensus
tend to be too high on dew points in unseasonably colder/drier
regimes.-- End Changed Discussion --
&&
.SHORT TERM /SATURDAY NIGHT THROUGH SUNDAY NIGHT/...
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The high begins to shift to the east Saturday night. There is
only a slight change to the air mass with very little return
flow. Aloft, SW flow will likely bring in some middle and upper
level moisture. These clouds may prevent ideal radiational
cooling, but should still see lows fall into the 20s for most
spots away from the immediate coast. The NYC metro likely only
falls into the lower 30s.
An amplifying upper trough begins to approach on Sunday with the
surface high moving further offshore. There will be an inverted
trough that lingers near the southeast coast. Once the upper trough
moves closer, it will interact with the inverted trough to organize
low pressure. The low will begin to lift towards the Middle Atlantic
coast late in the day on Sunday. Otherwise, clouds will increase
through the day with conditions remaining dry. Temperatures will
moderate into the lower and middle 40s for highs.
The upper trough and its associated energy/lift move near the
east coast Sunday night. Primary surface low pressure over
southern Canada will send a cold front towards the region
helping bring the Middle Atlantic low towards Long Island
overnight. Large scale ascent quickly increases with widespread
precipitation developing from south to north. Thermal profiles
support plain rain for the entire area. The rain may become
briefly moderate overnight especially as the surface low nears
the coast. The system is progressive and the model consensus is
in decent agreement that the rain will quickly taper off from
west to east early Monday morning. There may be some lingering
rain across eastern Long Island and southeast Connecticut for
the beginning of the morning commute. There is increasing
confidence the rain will be ending as the morning commute begins
in the NYC metro on NW. Some gusty winds up to 30 mph are
possible across the east end of Long Island and southeast
Connecticut. Some of the guidance has the low pressure a bit
broader which will keep winds on the lighter side.-- End Changed Discussion --
&&
.LONG TERM /MONDAY THROUGH THURSDAY/...
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Mid/upper-level trough is expected to build on Monday as the
surface low quickly exits up the New England coast into the
Canadian Maritimes. Lingering rain for eastern zones will
quickly clear Monday morning/early afternoon, leaving breezy
WNW winds for the remainder of the day and into the night.
Strong cold air advection is expected to set up behind the
exiting system as a trough continues to build in upper-levels.
Despite some remaining breezy conditions Monday night, strong
cooling should take hold with lows in mid/low-20s, with NYC
metro in the low-30s.
On Tuesday 850mb cold air advection continues to increase with
850mb temperature anomalies around negative 10-12C with a deep
-35dam anomalous 500 mb trough. All of this will help support
further cooling Tuesday into Wednesday with highs on Tuesday in
the low-40s to mid-30s and lows Tuesday night in the teens to
mid-20s with areas in the NYC metro around the low-30s. Possible
breezy winds may prevent temperatures from getting this cold,
but will increase cause for concern over wind chills.
On Wednesday the strong trough will weaken and flatten becoming
more zonal. Cyclonic flow aloft will keep partly cloudy skies
as a surface low track through Ontario into Quebec Wednesday
into Thursday. Wednesday night could be another cool night, but
with warm air advection starting aloft, cooling may not be as
strong.
Weak ridging develops on Friday with surface high pressure
building from the southwest.-- End Changed Discussion --
&&
.AVIATION /21Z FRIDAY THROUGH WEDNESDAY/...
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High pressure builds in from the west through this evening in
the wake of a passing cold front.
VFR. Midlevel clouds have scattered out at all terminals with just
some high cirrus streaming in from the SW.
Gusty NW winds 20-25kts are expected to continue over the next few
hours with the passage of the cold front. Gusts should continue
until 00Z or just after, as winds will diminish into the overnight.
Winds may become more westerly after daybreak into mid morning,
increasing to 5-10kts.
...NY Metro(KEWR/KLGA/KJFK/KTEB) TAF Uncertainty...
No unscheduled AMD expected.
OUTLOOK FOR 18Z SATURDAY THROUGH TUESDAY...
Sat: VFR.
Sun: VFR. MVFR possible late in the day with rain. MVFR with rain
Sunday night. SE wind 15-20kt, G25-30kt, becoming SW and diminishing
toward morning.
Mon: VFR at the NYC metro terminals and northwest. A chance of rain
early east with MVFR, then becoming VFR. WNW wind 15-20kt, G25-30kt.
Tue: VFR. W wind 15-20kt, G25-30kt.
Wed: VFR. W wind 10-15kt, G20-25kt.
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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Winds will begin to increase on the waters today, but should
remain below 25 kt until tonight behind a cold front passage.
There is higher confidence in 25 kt gusts over the ocean,
eastern Sound and Peconic and Gardiners Bays, but 25 kt gusts
are possible on all waters and have issued a Small Craft
Advisory for tonight. Sub-SCA conditions are then expected
Saturday through Sunday as high pressure builds into the area
and remains in control.
SCA conditions will be met throughout Monday into Wednesday
with gusts of 25kt or greater on ocean waters, only lasting
until Tuesday night for LI Sound and Bays. There is also a chance
of gales Monday through Monday night and will continue mention
this potential in the HWO on the ocean. Winds are expected to
weaken Wednesday night, but may reach SCA conditions again on
ocean waters and the LI Sound entrance Thursday.
Waves will be above 5 feet for all ocean waters through Monday
night, then only for eastern ocean zones on Tuesday. Wednesday
should stay below 5 feet before rising again during the day on
ocean waters on Thursday, subsiding Thursday night.-- End Changed Discussion --
&&
.HYDROLOGY...
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There are no hydrologic concerns through Sunday evening.
One half to one inch of rainfall is likely Sunday night into
Monday morning with no hydrologic concerns. Dry weather is
expected later Monday into the end of next week.-- End Changed Discussion --
&&
.TIDES/COASTAL FLOODING...
Astronomical tides will be increasing into early next week due
to a full moon early Monday morning. There is not much in the
way of forcing/surge this weekend. However, some of the guidance
brings the most vulnerable locations in the south shore back
bays of Nassau County close to minor benchmarks with the Sunday
morning high tide. Minor coastal flooding appears more likely
for the south shore back bays of Nassau and Queens, Western Long
Island Sound across coastal Westchester and coastal Fairfield
with the Monday morning high tide. A quickly developing low
pressure may help bring enough of a surge (only around
0.50-0.75 ft needed) to reach minor benchmarks. It looks more
marginal across the Lower NY Harbor at the present time.
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
CT...None.
NY...None.
NJ...None.
MARINE...Small Craft Advisory from 6 PM this evening to 6 AM EST
Saturday for ANZ331-332-340-345-350-353-355.
Small Craft Advisory from 6 PM this evening to 1 AM EST
Saturday for ANZ335-338.
&&
$$
SYNOPSIS...BR/DS
NEAR TERM...DS
SHORT TERM...DS
LONG TERM...BR
AVIATION...DBR
MARINE...BR/DS
HYDROLOGY...BR/DS
TIDES/COASTAL FLOODING...DS