000
FXUS61 KOKX 211731
AFDOKX
Area Forecast Discussion
National Weather Service New York NY
131 PM EDT Sat Oct 21 2023
.SYNOPSIS...
Low pressure south of Long Island strengthens as it moves towards
Rhode Island and SE Massachusetts and then into the Gulf of Maine
today into tonight. The low eventually moves into the Canadian
Maritimes by early Sunday. The low will then slowly move
eastward and weaken for the remainder of Sunday and into Monday.
By Monday, high pressure starts to build in from the west. This
high will be centered over the area early Tuesday and remain in
control through at least midweek. A weak cold front may move
through the area sometime at the end of the week, with high
pressure returning thereafter.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
The fcst has been updated to adjust rainfall totals for the rest
of the day, with ern CT expected to get the heaviest amounts as
the rain pivots in from the SE. In addition, removed tstms with
the convection focused invof the main low well offshore.
Vorticity maximum shifts east of the region this afternoon.
Larger scale in mid levels exhibits a negatively tilting trough
with cutoff low forming by early this evening in the Gulf of
Maine.
At the surface, low pressure will deepen as it moves into the
Gulf of Maine for this evening.
Rainfall lingers especially across Southern Connecticut and Long
Island where rainfall will remain likely through much of the
day. Some of the rain could be heavy at times with some enhanced
lift. Farther west, for NYC, NE New Jersey, and the Lower
Hudson Valley, outside of the possibility of some brief
instances of light rain from time to time, mainly dry
conditions are expected for the afternoon.
The pressure gradient will be tightening through this
afternoon in response to the strengthening low pressure area
moving into coastal New England. Winds were adjusted to above
model guidance to account for mixing down in the model BUFKIT
soundings. Generally, expecting gusty westerly winds. Winds will
range around 15 to 25 mph with gusts around 35 to 45 mph.
Wind gusts could potentially exceed 45 mph for some coastal
locations this afternoon especially along Long Island and
Southern Queens, but did not feel confident enough on the
frequency of occurrence. Feel the probabilities are still low
enough to not put up the wind advisory after assessing 10m wind
gust potential fields from the HRRR plus the upper percentiles
of wind gusts from the NBM. These datasets depict the 40+kt wind
gusts staying mainly offshore.
In addition, the lingering rain will mean mixing efficiency will
not be optimal as lapse rates will be more moist adiabatic and
less dry adiabatic. If rainfall is less than forecast and drier
air works in faster than previous forecast, then wind gusts
potential could increase in the subsequent forecast.
With the rain, overcast conditions as well as breezy flow,
temperatures will be staying below normal. Forecast highs are
mainly in the upper 50s to near 60.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH MONDAY NIGHT/...
Mid levels convey cutoff low moving into Canadian Maritimes with
another trough approaching from the west. At the surface, strong
low pressure will be moving from the Gulf of Maine into the
Canadian Maritimes.
Rainfall is expected to taper off in the evening for the eastern
parts of the region. Abundant clouds will remain. Used a blend
of raw model data consensus, MOS consensus and NBM for the
temperature forecast, ranging from the lower 40s to lower 50s
for the lows.
For Sunday, the trough will be moving across and will allow for
more clouds than sun and perhaps a brief light rain shower for
interior parts of the region with mid level positive vorticity
advection. Pressure gradient will still be tight allowing for
breezy westerly flow although winds will be of less magnitude
compared to the previous day and night.
A colder airmass will be developing in the region as main upper
level jet winds stay south of the region. Forecast high
temperatures on Sunday are mainly in the range from the low 50s
to the upper 50s.
For Sunday night, winds will decrease further but clouds will
remain abundant, mitigating radiational cooling. Lows forecast
range mainly in the low to upper 40s.
For Monday more ridging aloft takes place, allowing for greater
subsidence and more sun as surface high pressure starts to
build in from the west. Winds will further decrease and another
cooler than normal day is forecast for high temperatures Monday
which will be mainly in the lower 60s.
More optimized radiational cooling occurs Monday night with
mostly clear sky conditions and winds becoming nearly calm as
high pressure center moves overhead. There continues to be
potential for frost in outlying and interior parts of the
region. Lows will trend colder, ranging from the lower to mid
30s for outlying, interior sections to near 50 within NYC.
&&
.LONG TERM /TUESDAY THROUGH FRIDAY/...
Tranquil weather expected from Tuesday onward as high pressure will
remain in control through at least midweek. Several dry days with
sun can be expected. With a southerly flow setting up as the high
pushes off the East Coast Tuesday, temperatures through the week are
expected to be seasonably warm.
Global guidance is not in as good agreement for the end of next
week. Right now it looks like there is potential for a weak cold
front to pass through and bring some light showers. Given the
uncertainty, just stuck with NBM for PoPs which was mostly dry.
&&
.AVIATION /18Z SATURDAY THROUGH THURSDAY/...
-- Changed Discussion --
An area of low pressure rapidly deepens just east of the area
this evening as it tracks towards the Gulf of Maine into
tomorrow. High pressure builds in tonight from the west.
Conditions have become MVFR to VFR across the city terminals
with only a few outlying terminal still seeing less than MVFR.
VFR is expected to hold for tonight and tomorrow.
Most showers have cleared terminals with only very light showers
lingering in the TAFs through 20Z.
W to NW winds will increase in the coming hours 20 to 25 kt with
gusts at or around 30kt through this evening. Gusts diminish
somewhat tonight, but will still be in the 20 to 25 kt range.
Gusts remain the same tomorrow.
...NY Metro (KEWR/KLGA/KJFK/KTEB) TAF Uncertainty...
Timing of category changes could be off by a few hours.
OUTLOOK FOR 18Z SUNDAY THROUGH THURSDAY...
Sunday: Mainly VFR. W to NW wind gusts around 25-30 kt.
Monday: VFR. Gusty NW flow 15-20 kt in the morning.
Tuesday: VFR.
Wednesday: VFR.
Thursday: VFR.
Detailed information, including hourly TAF wind component forecasts,
can be found at: https:/www.weather.gov/zny/n90-- End Changed Discussion --
&&
.MARINE...
Already have SCA level seas on the ocean. Pushed earlier the
timing of the gale warning so that it is already in effect. The
non-ocean waters have their gale warning the same as before,
going into effect at 12PM this afternoon. For all marine zones,
the gale warning goes until 6AM Sunday.
SCA level conditions for the wind gusts remain on all waters
Sunday and into Sunday night but non-ocean waters are forecast
to start to lower below SCA late Sunday night. The ocean remains
with SCA level conditions for both wind gusts and seas Sunday
through Sunday night.
With greater influence of high pressure, conditions trend to
below SCA for all marine zones Monday into Monday night with the
weakening pressure gradient.
Thereafter, with high pressure in control, conditions will be below
Small Craft Advisory criteria through Wednesday morning. Waves build
to 5 ft on the ocean waters Wednesday afternoon with an increasing
SW flow developing, diminishing late Wednesday night into early
Thursday morning.
&&
.HYDROLOGY...
Additional rainfall of around and inch of rain is forecast
across mainly ern Connecticut through early this evening. Some
locally higher amounts are possible with potential for minor
flooding in poor drainage areas. Otherwise, no hydrologic
problems are expected.
There are no hydrologic concerns Sunday through next week.
&&
.TIDES/COASTAL FLOODING...
From the prolonged onshore fetch and piling of water, a few
sites in and around the South Shore Bays and possibly the lower
NY Harbor could reach minor coastal flood benchmarks for the
afternoon high tide cycle today. One mitigating factor will be
the NW offshore flow developing and increasing during the day.
Water levels are expected to stay below minor coastal flood
benchmarks. There could be an isolated occurrence where a tide
gauge just reaches its minor coastal flood benchmark for
instance near Freeport or Montauk, but confidence on this is
not high.
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
CT...None.
NY...None.
NJ...None.
MARINE...Gale Warning until 6 AM EDT Sunday for ANZ331-332-335-338-340-
345-350-353-355.
&&
$$
SYNOPSIS...JM/JP
NEAR TERM...JMC/JM
SHORT TERM...JM
LONG TERM...JP
AVIATION...BR
MARINE...JM/JP
HYDROLOGY...JM/JP
TIDES/COASTAL FLOODING...