000
FXUS61 KOKX 231439
AFDOKX
Area Forecast Discussion
National Weather Service New York NY
1039 AM EDT Sat Sep 23 2023
.SYNOPSIS...
The region will be in between high pressure in the Northern
Atlantic and Tropical Storm Ophelia well to the south and west
today. Ophelia is forecasted by the National Hurricane Center
to transition from tropical storm to a post-tropical depression
tonight into Sunday morning as it moves northward within the
mid-Atlantic. Meanwhile, an associated warm front will approach
the region tonight and stall south of Long Island this weekend.
The area of low pressure will continue to approach to close
this weekend before passing south of Long Island early next
week. This will be followed by high pressure building in from
Southeast Canada mid into late next week.
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
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
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Forecast remains on track. Only minor adjustments were made
based on current observations.
The forecast omega increases vertically as time progresses
further into the day with the atmospheric column getting close
to saturated.
The forecast from the National Hurricane Center has Tropical Storm
Ophelia moving northward inland across eastern North Carolina on
Saturday.
In the local area, the area will be within a tightening pressure
gradient between Ophelia to the south and west and high pressure in
the Northern Atlantic to the southeast of Nova Scotia.
Gusty easterly winds will be highest across NYC and Long Island and
decrease farther north across the Lower Hudson Valley and interior
Southern Connecticut. Highest gusts generally this afternoon
into evening, with max gusts close to 40 mph along the coast,
closer to 35 mph inland.
Increasing mid level positive vorticity advection with the approach
of mid level cutoff low as well as approach of southerly upper level
jet streak and its left front quad will enhance vertical lift
through Saturday. Layer precipitable waters increase to near 1.7 to
1.9 inches. Parallel flow from low to mid levels will allow for
training of convection.
So, this will lead to steady stratiform rain with some embedded
locally heavier rain from time to time. The threat for flash
flooding remains low so well below threshold for a flash flood
and therefore there is no flood watch in effect at this time.
Forecast highs will only be in the upper 50s to lower 60s, much
below normal for this time of year.-- End Changed Discussion --
&&
.SHORT TERM /6 PM THIS EVENING THROUGH MONDAY NIGHT/...
The forecast from the National Hurricane Center has Ophelia becoming
post-tropical and weakening to a depression Saturday night into
early Sunday morning.
An associated warm front will approach from the south and stall
south of Long Island.
The upper level jet streak and its left front quad shift farther
east of the region. With mid levels exhibiting some space between
positive vorticity and next positive vorticity with mid level cutoff
low to the southwest, there will be less vertical lift for rainfall,
leading to a lull in the rain. The rain will become more
intermittent. Forecast model BUFKIT profiles show a lack of omega as
well for much of the night. Layer precipitable waters also decrease
near a third to a half inch, down to near 1.3 to 1.4 inches for
Saturday night.
However for late night into very early Sunday morning, the mid level
cutoff low gets closer to the area with greater positive vorticity
advection moving into the local region. The back end of the upper
level jet streak will be moving south of Long Island, with its right
rear quad getting closer to the area. Enhanced lift accounting for
mid and upper level factors will be more present across the southern
sections of the region for NE NJ, NYC and Long Island.
POPs lower to chance for the first half of tonight and then
trend back to likely overnight into very early Sunday morning
for SW portions of the forecast region.
The forecast from the National Hurricane Center keeps Ophelia as
post-tropical as a post tropical depression. This low makes its
way towards the DelMarva Sunday into early Sunday evening.
Some forecast model BUFKIT profiles such as the NAM and some members
of the SREF convey a sharp increase in omega to greater magnitudes
than present on the previous day for Sunday morning. However, other
forecast model BUFKIT profiles do not depict the rapid increase or
magnitude of omega.
Models are depicting some elevated instability as conveyed by near
zero to slightly negative Showalter Indices for Sunday across the
coastal sections with cold pool aloft from cutoff mid level low
moving into the area by the start of Wednesday evening. The positive
vorticity advection increases during the day Sunday. However, the
cutoff low will be weakening with time.
Precipitable waters shown by forecast models return to around 1.8 to
1.9 inches on Sunday.
For Sunday night, low pressure traverses near to south of Long
Island along the stalled warm front. Mid level positive vort
maximum moves across as well but will be getting less organized
and weakening.
For Monday, weakening mid level flow will allow for the weakened low
to slow down and remain in the vicinity.
Weakening mid level trough pushes farther south on Monday night,
steering the low relatively farther south of Long Island. POPs
for rain showers will decrease with mainly dry conditions
anticipated.
Temperatures will remain below normal for high temperatures and
near to slightly below normal for low temperatures.
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
&&
.LONG TERM /TUESDAY THROUGH FRIDAY/...
Region in mid levels remains between troughs, one to the east
and one to the west. More uncertainty towards end of week but
mid level heights do not change too much. At the surface, high
pressure builds southward into the region later Tuesday through
Thursday night.
Mainly dry weather conditions expected. Some uncertainty
initially early Tuesday with how fast low pressure departs
farther away and location of low pressure towards end of the
week as well as the strength of high pressure. There are some
slight chance POPs for rain showers in these time periods.
&&
.AVIATION /15Z SATURDAY THROUGH WEDNESDAY/...
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*High impact aviation weather expected Today*
Tropical Storm Ophelia, over eastern North Carolina this
morning and lifts northward through tonight. Rain, moderate to
briefly heavy, continues with MVFR conditions. IFR expected to
develop for most terminals by 17Z and last through the
remainder of the TAF period. Afterward 21Z the rain should
taper off and become lighter into this evening with -SHRA. The
rain may completely end for a short time late tonight, before
returning early Sun morning.
ENE winds 15-20 kt, gusting 25-35 kt, with the highest gusts at
the coast, and points points east, with an isolated gust of
around 35 kt possible. The wind direction is not expected to
change, remaining NE through the day. Timing of the peak winds
is late morning into the mid to late afternoon. Winds should
decrease slightly toward this evening, but gusts will remain
through tonight and into Sunday morning with the winds generally
remaining out of the NE.
LLWS remains a possibility towards midday - early afternoon, but
confidence is too low to include in the TAFs at this time. Best
chances for LLWS will be across the coastal terminals. There will be
another chance for LLWS towards early Sunday morning, with
confidence too low at this time to include in TAFs.
...NY Metro (KEWR/KLGA/KJFK/KTEB) TAF Uncertainty...
Timing of any flight category changes may be off by an hour or two
and amendments are likely through the TAF period. LLWS occurrence
remains possible today and early Sun AM.
OUTLOOK FOR 12Z SUNDAY THROUGH WEDNESDAY...
Sunday: LLWS possible early. MVFR or lower likely in rain with
possible embedded thunder. Gusty winds to 25 kt 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...
HiRes ARW and FV3 show afternoon gusts in the 30 to 35 kt range for
non-ocean waters and in the 35 to 40 kt range for the ocean waters.
Multiple members of SREF indicate gale force gusts on the Long
Island Sound this afternoon at multiple hours. It appears the weight
of the guidance is favoring gales across much of the marine zones.
Looks to be confined to this afternoon and evening but some gales
could very well occur late tonight as well for non-ocean waters.
Hoisted the gale warning for the non-ocean waters considering the
aforementioned guidance for today into tonight. Gales remain in
effect for the ocean waters for today into tonight.
For Sunday, wind gusts mostly in the SCA range which will
gradually lower below SCA thresholds Sunday night across the
forecast waters. Ocean seas remain well into SCA range Sunday
through Sunday night. For early Sunday, there could be some
remaining localized areas with gale force gusts.
Another round of widespread SCA conditions early next week but
by midweek just ocean seas with SCA conditions in the forecast.
&&
.HYDROLOGY...
Storm total rainfall of near 2 to 3 inches forecast for much of the
region today through Monday. Maximum hourly rates still appear
to be mainly around a quarter to half inch but could get higher
Sunday with some thunderstorms. There remains a low chance for
flash flooding this weekend especially for any locations that
get locally more than 3 inches and if those locations are poor
drainage and low-lying.
&&
.TIDES/COASTAL FLOODING...
There is a high rip current risk for all Atlantic facing beaches
through Sunday early evening due to long period easterly wind
waves and E/S swells.
A high surf advisory has been extended for all coastal zones of
Long Island, including the ocean shorelines of Brooklyn and
Queens through early Sunday evening. 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 8 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 around 1 ft to develop for the 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.
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
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CT...Coastal Flood Advisory from 4 PM this afternoon to 8 PM EDT
this evening for CTZ009.
NY...Coastal Flood Advisory from 4 PM this afternoon to 8 PM EDT
this evening for NYZ071.
High Risk for Rip Currents through Sunday evening for NYZ075-080-
081-178-179.
High Surf Advisory until 8 PM EDT Sunday for NYZ075-080-081-
178-179.
Coastal Flood Advisory until 5 PM EDT this afternoon for
NYZ178-179.
NJ...None.
MARINE...Gale Warning until 6 AM EDT Sunday for ANZ331-332-335-338-340-
345-350-353-355.-- End Changed Discussion --
&&
$$
SYNOPSIS...JM
NEAR TERM...JM/BR
SHORT TERM...JM
LONG TERM...JM
AVIATION...MET
MARINE...JM
HYDROLOGY...JM
TIDES/COASTAL FLOODING...