000
FXUS61 KOKX 301811
AFDOKX
Area Forecast Discussion
National Weather Service New York NY
211 PM EDT Sun Apr 30 2023
.SYNOPSIS...
Deepening low pressure over the southeastern states tracks northeast
today and over the region tonight. The low then meanders over
the Great Lakes Monday before slowing moving over the northeast
through the middle of the week. An upper level trough will remain over
the area through the end of the week. High pressure begins to build
in over the weekend.
&&
.NEAR TERM /THROUGH TONIGHT/...
Forecast remains on track with the initial band of rain moving
through the area now.
Included Orange and Rockland counties in the Flood Watch in
effect through this evening as antecedent rains of 1-3 inches
have primed the area ahead of additional anticipated rainfall
into this evening.
Low pressure heads our way today with its center passing through the
forecast area this evening. Moisture depth and lift will be on the
weaker side this morning, so mainly chances of light rain/drizzle
with areas of fog to start.
As the low center draws closer this afternoon, moisture and lift
will increase. PWATs rise to around 1.5 inches, and large-scale lift
is enhanced by frontogenetic forcing, isentropic lift, mid-level PVA,
and upper divergence from the left-exit region of a jet streak.
Looks like there could be two separate periods where rainfall could
be heavy at times. This first occurs during the first half of the
afternoon where CAMs appear to reflect the aforementioned sources of
lift via a WNW-ESE oriented band of moderate to locally heavy
rainfall pushing in from the south. Then as the low center draws
nearer, elevated convection becomes more possible during the second
half of the afternoon into the evening. A llj comes into play as
well, but would have more impact over the eastern zones. Given the
low FFG values (mainly 1-hr) in response to the 2 to 3.50 inches of
rainfall that has recently fallen for some areas, have decided in
collaboration with WFO PHI to go with a Flood Watch for flash
flooding potential for all of our NJ zones this afternoon and
evening. FFG values are higher elsewhere, and currently do not have
enough confidence for sufficient flash flooding coverage to warrant
expansion of the watch elsewhere. See the hydrology section below
for more details. Not expecting any severe-level wind gusts with any
thunderstorms that occur due to a low-level inversion that will
likely hamper the occurrence, so the main focus will be the flooding
potential. Elsewhere where there is no Flood Watch, expecting mainly
minor/nuisance flooding, but can`t completely rule out flash
flooding.
Rain ends by late at night with the low shifting north of the area.
It`ll be breezy during the afternoon and nighttime with a lull in
the winds during the evening N and W of the city. High temperatures
mostly in the low 60s.
&&
.SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/...
Low pressure to our north will continue to interact with a large
closed upper low over the Great Lakes and Northeast on Monday and
Tuesday. Monday should start out dry, but there is a chance for an
afternoon shower, mainly NW of the NYC metro. Shower chances
increase late Monday night into Tuesday. This is due to potential
of more organized energy and positive vorticity advection occurring
as the upper low nears. There also appears to be a bit higher
probability Tuesday morning NW of NYC with the aforementioned
energy. Chances persist into Tuesday afternoon with steepening lapse
rates from the cold pocket aloft and some limited daytime heating.
High temperatures for both Monday and Tuesday will be below
normal.
&&
.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
Little change to the expected pattern in the extended. Upr trof will
remain over the area thru Fri. Cyclonic flow aloft will keep temps
blw average with chances for shwrs thru the period. Highs generally
in the 50s and lows in the 40s. The cold pool aloft will keep steep
lapse rates locked in and the area primed for convective pcpn,
particularly during the daytime hours. Any strong dpva could
help to enhance convection and produce some isold low topped
tstms, perhaps with some small hail. High pres then attempts to
build in from the west over the weekend as ridging builds over
the Midwest. This will result in lessening chances for shwrs,
and a warming trend. Portions of the area could hit the lower
70s by Sun.
&&
.AVIATION /18Z SUNDAY THROUGH FRIDAY/...
-- Changed Discussion --
Deepening low pressure over the mid Atlantic moves northeast,
passing over the terminals this evening, and then tracking to
the north late tonight. The low remains to the northwest through
Monday.
IFR, and locally IFR continues into late tonight, improving late
tonight to MVFR, and then becoming VFR Monday morning. Timing of
the improvements will be dependent on the track of low pressure
through the region.
Light rain, with periods of moderate to locally heavy rainfall
late afternoon into the early evening, continues into late
tonight, ending as low pressure tracks north. Isolated
thunderstorms are still possible, and may be an hour or two
later than currently in the forecast, and confidence is low with
areal coverage and timing.
Winds remain NE to E, briefly becoming SE to S early this
evening along the coast before becoming W to SW with the passage
of the low. Inland wind switch to NW to N, and then NW late
tonight. There will be a brief period of lighter winds as the
center of the low moves over the terminals. Monday winds will
be SW gusting 20-25kt. A brief period of LLWS is possible at
KGON 22Z to 00Z as a low level jet tracks near southeastern
Connecticut.
...NY Metro (KEWR/KLGA/KJFK/KTEB) TAF Uncertainty...
High confidence of IFR conditions into late tonight, with low
confidence on the timing and coverage of any convection that
will be possible 22Z to 04Z. Occasional gusts to around 20 kt
possible through early evening.
OUTLOOK FOR 18Z MONDAY THROUGH FRIDAY...
Monday afternoon and night: VFR. Chance of showers, local MVFR
possible.
Tuesday - Thursday: VFR. Chance of showers, MVFR at times.
Friday: VFR in the morning. Chance of afternoon showers with
MVFR, IFR possible.
Detailed information, including hourly TAF wind component forecasts,
can be found at: https:/www.weather.gov/zny/n90-- End Changed Discussion --
&&
.MARINE...
SCA has been extended on the ocean waters as well as eastern LI
Sound. Even after winds subside a bit on Monday, seas will remain
elevated due to a lingering swell. Elevated seas probably last
through Tuesday night, so the SCA will likely need to be
extended in time. Wind gusts this afternoon into evening could
briefly reach gale force on the ocean. For the remaining waters,
winds increase as the pressure gradient tightens in response to
an approaching low pressure center. SCA has been posted here
from noon today through noon Monday.
Seas on the ocean could remain at sca lvls on Wed. Winds and seas on
all waters are expected to remain blw sca lvls Thu-Sat
&&
.HYDROLOGY...
Rainfall of 1.5 to as much as locally 3.25 inches has fallen
through Saturday mid afternoon, and an additional 1 to 1.75,
with locally up to 2 inches across Connecticut, is possible from
through this evening. Minor nuisance flooding will be possible
once again this afternoon into this evening across poor
drainage and urban areas.
No hydrologic impacts are expected Monday through next weekend.
&&
.TIDES/COASTAL FLOODING...
A strong SE flow due to a deepening low pressure today may bring
evening high tide levels to minor flood benchmarks. The main concern
continues to be for the south shore Back Bays of southern Nassau and
southern Queens, western Great South Bay along southwest Suffolk,
and SW CT coast along the Western Long Island Sound. Astronomical
tides are low, so approximately 2 to 3 ft surge is needed to bring
water levels to minor flooding at these locations this evening.
A coastal flood statement remains in effect for southern Nassau,
southern Queens, southwest Suffolk, and coastal Fairfield as a
consensus of the guidance brings water levels to just touching minor
flooding benchmarks. A few of the more vulnerable locations could
see a few tenths above minor, but widespread minor flooding is not
expected at this time. Elsewhere, water levels should remain below
minor flooding during the evening high tide.
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
CT...None.
NY...Flood Watch until midnight EDT tonight for NYZ067-069.
NJ...Flood Watch until midnight EDT tonight for NJZ002-004-006-
103>108.
MARINE...Small Craft Advisory until noon EDT Monday for ANZ331-335-338-
340-345.
Small Craft Advisory until 6 PM EDT Monday for ANZ332-350-353-
355.
&&
$$
SYNOPSIS...12/JC
NEAR TERM...JC/MW
SHORT TERM...JC/DS
LONG TERM...12
AVIATION...MET
MARINE...12/JC
HYDROLOGY...12/JC
TIDES/COASTAL FLOODING...