000
FXUS61 KOKX 181800
AFDOKX
Area Forecast Discussion
National Weather Service New York NY
200 PM EDT Mon Sep 18 2023
.SYNOPSIS...
A low pressure system impacts the region today as it tracks up
the coast. High pressure builds Tuesday and remains over the
area through early Friday before shifting offshore late Friday.
Low pressure then approaches from the south on Saturday,
impacting the area late over the weekend.
&&
.NEAR TERM /THROUGH TONIGHT/...
-- Changed Discussion --
A coastal low pressure system off the NJ shore as of 17Z passes
just to our south and east today as it tracks up the coast. A
broad area of steady light rain, mainly north and east of the
center, will continue to push into southern New England and out
of the local region. Behind it, more intermittent showers
persist into late afternoon until drier air is able to work in
this evening. Forecast remains on track and previous discussion
follows.
Upper energy rotating through the eastern portion of the upper
trough was deepening a low off the southeastern and Carolina
coast. This low will track slowly north to north/northeast
today, and then pass to the east this evening. Precipitable
water values remain from around 1 1/2 to 1 3/4 inches today,
with slow storm motion and rain tracking across the same areas,
locally moderate rainfall will occur. The heaviest rainfall is
expected across portions of southeastern Connecticut and into
Long Island as isentropic lift will be maximized across these
areas in addition to the slow moving rain and training across
the region. Also, isolated thunderstorms will be possible across
Connecticut and Long Island later this afternoon, producing
locally heavy rain, as a low level low and thermal ridge move
across the region. While CAPE and instability will be rather
weak, the upper lift with the low level low may be enough for a
few isolated thunderstorms.
The upper low becomes slightly negative late in the day into
this evening, and lifts the surface low to the northeast of the
region this evening, with precipitation ending.-- End Changed Discussion --
&&
.SHORT TERM /TUESDAY THROUGH WEDNESDAY/...
Tranquil weather will be across the region Tuesday through
Wednesday as an upper trough across the northeast moves to
southeastern Canada as an upper ridge builds into the upper
midwest and Great Lakes region, with heights rising across the
area Tuesday through Wednesday. Meanwhile, surface high pressure
builds into the area by Tuesday night and remains Wednesday.
Temperatures will be near seasonal normals.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
No real significant changes to the long term and stuck close to the
NBM during this period.
A fairly tranquil period in store for much of the extended with a
dry period continuing Wednesday night through Friday. Global
ensembles are in good general agreement with the evolution of the
synoptic pattern over this period, and as such the NBM was used as
the basis for this forecast update.
Ridge axis slowly builds to the east during midweek before moving
offshore by Saturday. By week`s end, a slow moving upper low
originating over the southeast pushes slowly north and is somewhat
impeded by the ridging in place over the northeast. As this upper
low progresses north, the chances for unsettled weather/clouds and
precipitation increase into next weekend.
With respect to sensible weather, dry conditions are expected under
subsidence and surface high pressure Wednesday night through early
Saturday. Some high level clouds may begin to move into the area by
Friday in advance of the system that approaches from the south.
Otherwise, the incoming air mass is not anomalously warm or humid,
so daily highs near climatological norms, in the mid and upper 70s,
are forecast through the period. Near normal lows are also expected,
in the upper 50s to near 60.
An inverted trough associated with the main sfc low over the
southeast will approach the area Saturday. Moisture advection
increases on Saturday (sfc dewpoints back into the 60s) with
probability of precip. chances increasing by Saturday afternoon into
Sunday. NBM probabilities of >1" in any 6 hour period through Sunday
remain low at this time, less than 10% over the past few cycles,
suggesting little concern for excessive rainfall rates with the
system at the onset.
&&
.AVIATION /18Z MONDAY THROUGH SATURDAY/...
-- Changed Discussion --
An area of low pressure moves through today and east of the
region tonight. High pressure builds in on Tuesday.
Rain showers continue this afternoon with mainly IFR conditions.
Rain showers appear to be getting lighter across NYC terminals
and terminals north and west so visibilities for those will be
mostly MVFR to VFR but ceilings remain mainly IFR. Another round
of heavier showers is possible early this evening with perhaps
IFR visibilities before all rain comes to an end tonight.
There could very well be some fluctuation between MVFR and IFR
through the afternoon. Some occasional brief LIFR will be
possible.
VFR eventually returns tonight as rain showers taper off from
west to east.
Winds are generally light, less than 10 kt, from a general E
direction. The winds will become more from the NE direction
this afternoon and then a change to a more NW direction going
into tonight. Tonight into Tuesday wind speeds increase to near
10-15 kt. A few gusts near 15-20 kt are possible tonight.
However, more frequent gusts to near 20-25 kt are expected on
Tuesday, generally in the late morning and afternoon.
...NY Metro (KEWR/KLGA/KJFK/KTEB) TAF Uncertainty...
End time of rain showers could be off by 1-2 hours.
Timing of end of IFR and MVFR could be off by 1-3 hours.
Categories could very well fluctuate through the early evening
between MVFR and IFR.
OUTLOOK FOR 12Z TUESDAY THROUGH SATURDAY...
Tuesday through Friday: VFR.
Saturday...MVFR possible with a chance of rain showers. E gusts
near 15-20 kt.
Detailed information, including hourly TAF wind component forecasts,
can be found at: https:/www.weather.gov/zny/n90-- End Changed Discussion --
&&
.MARINE...
-- Changed Discussion --
An increasing and gusty west to northwest flow develops late
this evening and tonight behind departing low pressure, and
gusts on the ocean waters may be near 25 kt at times. However,
southeast to south swells will be increasing late today into
tonight from distant Tropical Storm Nigel, with ocean seas
reaching SCA levels. The seas will remain elevated through
Tuesday, and possibly into Tuesday evening as swells continue. A
Small Craft Advisory has been issued for the ocean waters
tonight and Tuesday. Swells linger into Wednesday, and ocean
seas may be near SCA levels east of Moriches Inlet.
Toward Wednesday morning and through Wednesday winds and seas
will be below SCA level across the forecast waters.
Winds remain below SCA levels across the forecast waters
Wednesday night. East to southeast swells from distant Tropical
Storm Nigel could bring elevated seas to the ocean waters
Thursday and Thursday night.
Monitor https:/www.weather.gov/okx/tropical or
https:/www.nhc.noaa.gov for the latest NHC forecasts on Tropical
Storm Nigel.-- End Changed Discussion --
&&
.HYDROLOGY...
-- Changed Discussion --
Rainfall into this evening will range from around 1/2 inch
across the western and northern areas to as much as 1 1/2 to 2
inches across southeastern Connecticut and the twin forks of
Long Island. Localized nuisance flooding will be possible where
higher amounts occur.
No hydrologic problems are expected later this evening through
next weekend.-- End Changed Discussion --
&&
.TIDES/COASTAL FLOODING...
There is a moderate rip current risk today. Tuesday there is a
moderate risk at the NYC, southern Nassau, and southwestern
Suffolk ocean beaches, and a high risk at the southeastern
Suffolk ocean beaches. A high risk may be needed at the
southwestern Suffolk beach Tuesday. This is in a SE to S 2-3
foot swell today, building to 4-5 feet Tuesday with 6-9 second
periods. Surf heights will be building to near 7 feet Tuesday
and a high surf advisory may be needed.
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
CT...None.
NY...None.
NJ...None.
MARINE...Small Craft Advisory from 6 PM this evening to 6 PM EDT
Tuesday for ANZ350-353-355.
&&
$$
SYNOPSIS...JP/MET
NEAR TERM...DR/MET
SHORT TERM...MET
LONG TERM...JP
AVIATION...JM
MARINE...JP/MET
HYDROLOGY...JP/MET
TIDES/COASTAL FLOODING...DR