000
FXUS61 KOKX 272033
AFDOKX
Area Forecast Discussion
National Weather Service New York NY
433 PM EDT Wed Sep 27 2023
.SYNOPSIS...
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High pressure will remains centered north of the area through
Thursday, then give way to an inverted surface trough and weak
low moving northward along and off the coast Thursday night
into Friday. The low will move slowly east on Saturday, with
high pressure building in its wake and remaining dominant into
next week.-- End Changed Discussion --
&&
.NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
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MSAS analyzed a 1034 high over Quebec at 18Z. This was higher than
both the 12Z runs of the GFS and NAM. At the same time, low pres was
placed off of Hatteras. This combo should continue to produce at
least some lgt winds tngt, especially near the coasts, with perhaps
some sheltered areas decoupling. As a result, went close to the
NBM for temps. If calm winds do materialize, particularly
across the interior, lows will be colder than currently fcst.
With the mixing winds expected, do not expected widespread fog attm.
Did place some patchy fog in the river valleys late tngt. As with
temps, less wind than fcst will equal greater coverage of fog.-- End Changed Discussion --
&&
.SHORT TERM /6 AM THURSDAY MORNING THROUGH THURSDAY NIGHT/...
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A mid lvl trof approaches on Thu, allowing mid lvl flow to draw
moisture back into the region. This should result in increasing
clouds. With the high a bit stronger than modeled, a dry fcst for
the day seemed reasonable with ENE llvl flow locked in and current
dewpoints on Cape Cod around 50.
The temp fcst is for warmer highs across the nrn zones with more
sunshine.
Increasing frogen around 2500 ft helps with overnight omega across
the cwa. With the moisture deepening, rain chances will increase
steadily Thu ngt. The thickening clouds across the area will lead
to nearly homogeneous overnight temps with the NBM closely
followed.-- End Changed Discussion --
&&
.LONG TERM /FRIDAY THROUGH WEDNESDAY/...
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Tricky Fri-Fri night with forcing from the incoming upper
trof/weak closed low from the west, and low level
moisture/convergence/WAA with an sfc inverted trough/weak low
riding up the coast. ECMWF in general is stronger and generating
heavier rain with both, but it should be noted that any areas
of heavier rain with this combo of systems will likely be more
on the mesoscale side, with usual placement and timing errors.
At any rate, the entire region should see rain daytime Fri,
mainly from NYC metro north/west earlier in the day, then
throughout as the day progresses. Best rain chances should then
shift more to the east across S CT and Long Island Fri night.
With ECMWF slower and a little bit stronger with the upper low
and sfc low off the coast on Sat, rain chances could linger into
daytime Sat. especially for Long Island and S CT. Conds should
dry out thereafter as high pressure begins to build into the
area at the sfc and aloft, with an associated warming trend.
Sided with higher of NBM and NBM 75th percentile guidance temps
going into early/mid next week, with high temps at least in the
mid/upper 70s across most of the area, with lower 80s possible
for urban NE NJ and the interior valleys Mon-Tue. A more onshore
flow as the sfc high retreats a little offshore could result in
slightly cooler temps for Wed at least along the coast.-- End Changed Discussion --
&&
.AVIATION /20Z WEDNESDAY THROUGH MONDAY/...
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High pressure remains across eastern Canada and the Northeast
through Thursday.
VFR through tonight. MVFR becomes likely - starting around 12Z
for the city terminals and KISP, with MVFR possible for KHPN
and KSWF later in the morning. ENE winds 10-15 kt this
afternoon, diminishing and backing slightly tonight before
increasing back to 10-15 kt for Thursday.
...NY Metro (KEWR/KLGA/KJFK/KTEB) TAF Uncertainty...
Chance that KJFK winds veer more easterly at times before 00Z.
Timing of MVFR onset may be off by a couple of hours.
OUTLOOK FOR 18Z THURSDAY THROUGH MONDAY...
Thursday: MVFR becomes VFR by late in the day. Slight chance of
showers.
Friday: IFR and rain. ENE winds G25-30 kt, mainly along the
coast.
Saturday: MVFR/IFR and rain in the morning, improving to VFR by
late. NE winds G20-25kt possible in the morning.
Sunday and Monday: VFR.
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 generally remain blw sca lvls thru Thu ngt. A few gusts
close to 25 kt possible on the ocean thru the period. Seas on
the ocean will remain aoa 5 ft, and the sca has been extended
thru Thu ngt.
An extended period of SCA conds is likely for the ocean into
early next week via incoming swell from an offshore low and from
distant tropical systems in the Atlantic.-- End Changed Discussion --
&&
.HYDROLOGY...
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Rainfall from Thu night into Sat somewhat uncertain. Areas from
NYC north/west and across SE CT/eastern Long Island appear most
likely to see at least 1-1.5 inches. A stronger offshore
trough/low could Fri into Sat could result in heavier rain of
over 2 inches for parts of SE CT/eastern Long Island. Duration
of this rainfall should limit any hydrologic impact.-- End Changed Discussion --
&&
.TIDES/COASTAL FLOODING...
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Diminishing easterly winds and subsiding swells on the ocean
will reduce the areal extent of coastal flooding for tonight`s
high tide cycle. In most cases, water levels will be lower.
However, the south shore back bays of Nassau will likely have
a more widespread event with 1 to locally 2 feet of inundation
expected in vulnerable areas near the waterfront and shoreline.
Therefore, a coastal flood advisory remains in effect for
southern Nassau. Elsewhere, statements are being used to address
localized minor coastal flooding across portions of Lower NY
Harbor, SW Suffolk, and southern Fairfield in CT. While guidance
is generally indicating a non-event for SW Suffolk tonight,
models have been know to struggle at times in prolonged easterly
flow events.
For the remainder of the week, additional episodes of coastal
flooding are likely due to rising astronomical tides (as low as
1/4-1/2 ft needed to reach minor) and persistent E/NE flow and
easterly wind wave/swell.
NOTE: The Peconic River at Riverhead tidal gauge is out of
service (had been reading too high). The gauge is being looked
into by our partners at the USGS.-- End Changed Discussion --
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
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CT...None.
NY...Coastal Flood Advisory until 9 PM EDT this evening for NYZ179.
NJ...None.
MARINE...Small Craft Advisory until 6 AM EDT Friday for ANZ350-353-355.-- End Changed Discussion --
&&
$$
SYNOPSIS...JMC/BG
NEAR TERM...JMC
SHORT TERM...JMC
LONG TERM...BG
AVIATION...JC
MARINE...JMC/BG
HYDROLOGY...JMC/BG
TIDES/COASTAL FLOODING...JMC