000
FXUS61 KOKX 221948
AFDOKX
Area Forecast Discussion
National Weather Service New York NY
348 PM EDT Fri Sep 22 2023
.SYNOPSIS...
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High pressure to our north will shift east into the Atlantic
tonight. Meanwhile, Tropical Storm Ophelia will make landfall in
North Carolina before devolving into a post-tropical depression
early Sunday morning. The low along the Delmarva weakens Monday
and drifts south as high pressure builds into eastern Canada.
The high will build southward Monday night through Wednesday,
and then remains centered over New England into Friday.
Meanwhile, low pressure along the Carolina and mid Atlantic
coast deepens Wednesday through Friday.
For the latest forecasts on Tropical Storm Ophelia, refer to the
National Hurricane Center at www.nhc.noaa.gov and/or the NWS New
York office`s tropical page at weather.gov/okx/tropical-- End Changed Discussion --
&&
.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
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High pressure to our north continues to exit east tonight. Tropical
Storm Ophelia to our south will continue to increase the pressure
gradient tonight. Winds will remain out of the east 10-15 mph with
20-25 mph gusts becoming.
Strong winds and increased cloud cover from Ophelia to our south
will lead to low temperatures overnight in the mid/upper-50s north,
with low-60s for coastal and southern portions of our area.-- End Changed Discussion --
&&
.SHORT TERM /6 AM SATURDAY MORNING THROUGH SUNDAY NIGHT/...
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Tropical Storm Ophelia will make landfall in North Carolina where it
will slowing track through Virginia and Maryland where it is
expected to transition into a post-tropical depression with eventual
dissipation by Sunday night. While it will be making landfall well
to our south Saturday morning, we will see most of our impacts from
Ophelia Saturday into Sunday.
CAMs are in good agreement that a wide band of precip will sweep
northward well away from Ophelia`s center of low pressure tracking
up the east coast, arriving early Saturday morning. Precip will
likely be stratiform and widespread in coverage SAturday morning and
afternoon. Some models indicate an increase in rainfall intensity on
the back side of the wide band of precip Saturday evening into
possibly early Sunday before a temporary lull in the precip as it
transitions into a more showery form of precipitation. Rainfall
rates will likely be 0.25-0.50"/hr Saturday evening into early
Sunday. The timing of the higher rainfall rates is in agreement with
CAMs.
Sunday is when confidence in exact rainfall impacts becomes a little
uncertain. Models diverge on their solutions with Ophelia`s track
and persistence. Some have it hanging on until Monday tracking north
through Virginia and Maryland while others have the system
completely dissipating Sunday, which appears to be in agreement
with the NHC`s forecast. With Ophelia expected to dissipate and
stall over Maryland, rainfall on Sunday will likely be more
scattered and showery in nature.
Rainfall totals Saturday through early Monday will be 2.5-3"
for southern portions of the CWA and 2-2.25" for northern
portions of the CWA. Much of this, around 1.5-2", will fall on
Saturday with the initial wave of precip.
Aside from rainfall, winds will be the other primary impact felt on
land. The pressure gradient will increase winds across the CWA, with
the strongest winds expected across southern portions of the area.
Winds will increase Saturday morning reaching their peak
Saturday afternoon and evening with wast winds sustained 15-20
mph with gusts 30-35 mph. An isolated 40 mph gust can not be
ruled out. As it stands now, this will not meet criteria for a
Wind Advisory. Northern portions of the CWA may only see gusts
around 25 mph during this peak wind period. Winds will gradually
subside SAturday night into SUnday morning with gusts up to 30
mph through Sunday morning, dropping to 20 mph gusts by Sunday
evening as the pressure gradient weakens from a dissipating
Ophelia.
Temperatures will be moderated by the rain and cloud cover this
weekend with highs expected to be in the mid-60s and lows in the low-
60s across the area.
Please see Marine and Coastal FLooding sections below for more
impacts this weekend.-- End Changed Discussion --
&&
.LONG TERM /MONDAY THROUGH FRIDAY/...
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Low pressure along the Delmarva Monday morning will be weakening
through the day and into Monday night as upper ridging across
northern Canada builds southward, and heights rise slowly across the
region. There are guidance differences as to how far north the
precipitation shield will extend and for what period of time, Monday
into Monday night. As the high and upper ridge build southward
during this period the surface low drifts southward with the
precipitation ending north to south.
The NBM probabilities are a little to high and north and used a
blend of the NBM and GFS. The high builds southward into New England
Wednesday and then remains through Friday. A prolonged easterly flow
around the high will keep the region cool through the week, with
temperatures 5 to as much as 10 degrees below normal. Thursday night
into Friday precipitation may return as the weak, to nearly
dissipated low along the Carolina and mid Atlantic coast begins to
deepen. Again there is uncertainty as to how far north the upper
closed low, and surface low, will move into the ridge, and at this
time leaned more toward the NBM probabilities.-- End Changed Discussion --
&&
.AVIATION /20Z FRIDAY THROUGH WEDNESDAY/...
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*High impact aviation weather likely Saturday*
High pressure retreats this evening with VFR conditions. TS Ophelia
will move inland over the Carolinas tonight and start to lift
northward. Rain and MVFR conditions will develop after 08z
Saturday....IFR expected to develop by 15z Saturday. The rain will
become more widespread and become moderate to locally heavy after
12z. Rain should become showery in nature Saturday afternoon and
evening.
E winds increase to 10-15kt with gusts to 25kt this evening.
The gusty east winds are expected to remain much of the night
and into Saturday with gusts to 35 kt possible by
midday. Strongest winds likely at coastal terminals points
east. Winds should decrease slightly toward Sat evening.
LLWS remains a possibility, but confidence is too low to
include in the TAFs at this time. Best chances for LLWS will be
across the coastal terminals.
.NY Metro (KEWR/KLGA/KJFK/KTEB) TAF Uncertainty...
Timing of MVFR or lower cigs may be off by an hour or two late
tonight into Saturday morning.
Amendments likely Saturday for changing flight categories.
OUTLOOK FOR 18Z SATURDAY THROUGH WEDNESDAY...
18z Saturday and Sunday: MVFR or lower likely in rain with
possible embedded thunder. Gusty winds to 30kt possible.
Monday: Mainly VFR. MVFR possible in showers.
Tuesday and Wednesday: Mainly 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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Conditions have become rough on the ocean waters today and will
start to become rough for NY Harbor and the South Shore Bays
tonight. A Small Craft Advisory will remain in effect tonight
for all ocean waters, NY Harbor and South Shore Bays with a
Small Craft Advisory starting for the the LI Sound and Eastern
Bays at 6pm. All Small Craft Advisories will continue through
8am Sunday except for ocean waters which will be upgraded to a
Gale Warning 6am Saturday.
Saturday gusts across ocean waters will be 35-40 kts with 10-13
ft waves. SUnday winds and waves gradually subside, starting
with gusts of 25 kts reducing to 15 kts. Waves will drop from
10 feet Sunday morning to 7 feet by Sunday night.
A prolonged period of east to northeast flow remains Monday through
at least Wednesday night between high pressure centered across
eastern Canada and weak low pressure remaining off the Delmarva to
mid Atlantic coast. Winds and gusts will briefly diminish late
Wednesday into Wednesday night as the high pushes farther to the
south and the low weakens. Then Thursday into Friday the easterly
flow increases as low pressure deepens along the Carolina and mid
Atlantic coast. Small craft advisory conditions will be on-going
across all the the non ocean forecast waters, with the exception of
New York Harbor, Monday and Monday night, and then just the far
eastern Sound into Tuesday. On the ocean waters SCA conditions will
be on-going Monday into Wednesday, with a brief lull possible later
Wednesday night, before increasing once again Thursday.-- End Changed Discussion --
&&
.HYDROLOGY...
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Storm total rainfall of near 2 to 3 inches forecast for much of the
region from late tonight through Monday morning. Maximum hourly
rates appear to be mainly around a quarter to half inch.
There will be a low chance for flash flooding especially for any
locations that get locally more than 3 inches and if those locations
are poor drainage and low-lying.-- End Changed Discussion --
&&
.TIDES/COASTAL FLOODING...
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There is a high rip current risk for all Atlantic facing beaches
through Sunday due to long period easterly wind waves and E/S swells
A high surf advisory has been issued for all coastal zones of
Long Island, including the ocean shorelines of Brooklyn and Queens
for Saturday into Sunday morning. Breaking waves of 6 to 10 ft are
forecast from a combo of E/S long period swells. This will lead to
beach flooding and erosion, with scattered areas of dune erosion.
The threat for localized overwashes is low at this point. Surf will
subside to 4 to 7 Sunday afternoon, but could continue at that level
into early next week with onshore flow.
Strengthening E/NE flow ahead of an approaching warm front will allow
for surge of 1 1/2-2 ft to develop for the Sat aft/eve high tide,
resulting in minor coastal flooding along the Lower NY/NJ Harbor,
Jamaica Bay, Great South Bay of Nassau County, as well as coastal
Westchester and Fairfield counties. Elsewhere across LI and NYC,
generally localized minor coastal flooding expected due to combo of
wave action and elevated water levels.
Another round of localized minor coastal flooding is likely for
Lower NY/NJ harbor and southern bays of NYC/LI on Sunday with a
persistent but weakened onshore flow. Additional rounds of minor
coastal flooding are possible for next week as astronomical tides
continue to increase, and E/NE flow possibly strengthening depending
on evolution of TS Ophelia.-- End Changed Discussion --
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
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CT...Coastal Flood Advisory from 4 PM to 8 PM EDT Saturday for
CTZ009.
NY...Coastal Flood Advisory from 4 PM to 8 PM EDT Saturday for
NYZ071.
Coastal Flood Advisory from 1 PM to 5 PM EDT Saturday for
NYZ074.
High Risk for Rip Currents through Sunday evening for NYZ075-080-
081-178-179.
High Surf Advisory from 6 AM Saturday to 11 AM EDT Sunday for
NYZ075-080-081-178-179.
Coastal Flood Advisory from 1 PM to 7 PM EDT Saturday for
NYZ178-179.
NJ...Coastal Flood Advisory from 1 PM to 5 PM EDT Saturday for
NJZ006-106-108.
MARINE...Small Craft Advisory until 8 AM EDT Sunday for ANZ331-332-335-
340.
Small Craft Advisory until 8 AM EDT Sunday for ANZ338-345.
Small Craft Advisory until 6 AM EDT Saturday for ANZ350-353-
355.
Gale Warning from 6 AM Saturday to 6 AM EDT Sunday for ANZ350-
353-355.-- End Changed Discussion --
&&
$$
SYNOPSIS...BR/MET
NEAR TERM...BR
SHORT TERM...BR
LONG TERM...MET
AVIATION...IRD
MARINE...BR/MET
HYDROLOGY...BR/MET
TIDES/COASTAL FLOODING...NV