127
FXUS61 KOKX 220956
AFDOKX
Area Forecast Discussion
National Weather Service New York NY
556 AM EDT Mon Jul 22 2024
.SYNOPSIS...
A stalled front remains over the area today and lifts north tonight.
Another frontal boundary approaches from the south, with a wave of
low pressure passing over or just south of the area late tonight
into Tuesday morning. A couple more waves of low pressure will pass
through the area through Wednesday night. A cold front moves through
Thursday night into Friday morning. Weak high pressure builds in
from the west Friday into next weekend.
&&
.NEAR TERM /THROUGH TONIGHT/...
-- Changed Discussion --
A weakening cold front continue to approach this morning. This
boundary will likely settle over the northern half of the area.
Another frontal boundary that has been stalled offshore for
several days will also lift north tonight towards the area. The
area remains on the eastern side of a broad upper level trough.
The first of many embedded shortwave troughs will approach from
the southwest tonight, helping a frontal wave deepen. This wave
will pass over or just south of the area late tonight.
A mostly dry day is expected, with increasing mid and high level
clouds ahead of the approaching shortwave. Even without much
clearing today, the area should still be able to destabilize,
especially north and west of NYC given the warm, moist
southerly flow. The CAMs generally show SBCAPE values peaking
this afternoon around 750-1000 J/kg. With the stalled frontal
boundary over the area, and some upper level disturbances
approaching ahead of the main shortwave, some convective
activity is expected, mainly north and west of NYC. Anything
that develops could contain lightning. 0-6km shear is weak and
will only be decreasing during the day, so severe thunderstorms
are not likely, but there is potential for any stronger storm
that develops to produce gusty winds.
The aforementioned frontal wave will bring more widespread showers
and thunderstorms during the overnight period. There is general
agreement that the wave will pass just south of the area, bringing
the higher rainfall totals to eastern Long Island and southeast CT.
However, there is still some uncertainty with the strength of the
wave, with the NAM continues to show a stronger low with more
higher rainfall totals. This is an outlier for now, but should
the guidance start trending this way, rainfall totals could be
higher for the southern half of the area. Chances of
showers/thunderstorms start increasing late this evening and
peak late tonight. Periods of moderate to locally heavy rain are
possible. The threat for flash flooding is low at this time
given the highest totals will likely be across areas that can
handle it, but minor urban and poor drainage flooding is
possible. Given pwats near 2 inches, localized rates of 1 inch
per hour are possible.-- End Changed Discussion --
&&
.SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/...
The area remains on the eastern side of the broad upper level
trough through the short term period. The frontal boundary will
also remain over or near the area through this period. This will
result in continued unsettled weather, with a couple more
frontal waves bringing chances of moderate to heavy rainfall.
While PoPs continue through Wednesday night, this will not be a
complete washout. Tuesday will actually be mostly dry, with
just some isolated to scattered showers and thunderstorms
around. Slight height rises are expected ahead of the next
shortwave and we may get some breaks of sun later in the day.
The next chance of more widespread showers and thunderstorms
will be Tuesday night into Wednesday with the next frontal wave.
Uncertainty increases thereafter with another wave possible again
Wednesday night, although the bulk of the rain from this wave
may end up offshore. Again, at this time, the threat for flash
flooding is low, with instances of minor urban and poor drainage
flooding more likely.
&&
.LONG TERM /THURSDAY THROUGH SUNDAY/...
Low pressure is expected to move northeast over southern Canada, and
then into the Canadian Maritimes Thursday into Friday. This low will
send a cold front across the region Thursday night into Friday
morning. With a humid airmass across the region there will be the
potential for rounds of moderate to briefly heavy rainfall with any
of the waves of low pressure. After the frontal passage high
pressure will build in from the west, bringing a drier airmass to
the region.
The long term period will feature near normal high temperatures,
with overnight lows slightly above seasonal normal as dew points
will remain in the mid 60s to possibly into the lower 70s. Dew
points will be somewhat lower, in the lower and mid 60s, Friday
through next Sunday.
&&
.AVIATION /10Z MONDAY THROUGH FRIDAY/...
A frontal boundary remains in the vicinity through early this
afternoon, then lifts back to the north late this afternoon.
Low pressure develops along an old frontal boundary south of the
area and tracks northeast, just south of Long Island tonight.
VFR through this afternoon. MVFR conditions move into the area
tonight with showers in association with the aforementioned low
pressure. An isolated thunderstorm is possible this evening onward.
Light southerly winds or light and variable winds through daybreak
today. Winds become S to SE around 10 kt to 15 kt this afternoon,
before diminishing early tonight with the low pressure in the
vicinity.
...NY Metro (KEWR/KLGA/KJFK/KTEB) TAF Uncertainty...
No amendments expected through this afternoon. Amendments expected
early this evening with uncertainty in lower flight categories
associated with showers. An isolated thunderstorm is possible from
this evening onward.
OUTLOOK FOR 06Z TUESDAY THROUGH FRIDAY...
Tonight: MVFR or lower in SHRA.
Tuesday: MVFR early morning possible, improving to VFR.
Tuesday night through Thursday: MVFR or lower in SHRA/isolate TSRA.
Friday: MVFR or lower possible in the morning with SHRA, otherwise
VFR.
Detailed information, including hourly TAF wind component forecasts,
can be found at: https:/www.weather.gov/zny/n90
&&
.MARINE...
Winds and waves are expected to remain below Small Craft Advisory
criteria through Wednesday night. However, wave heights are expected
to build to 4 feet on Tuesday and then could approach 5 ft Wednesday
into Wednesday night.
Winds and waves are expected to remain below SCA criteria from
Thursday onward. However, with a cold front moving through Thursday
night into Friday morning, gusts may reach SCA conditions on the
ocean and with a persistent southwest flow ocean seas may build to
marginal SCA levels into early Thursday. However, right now the
chances are low for SCA.
&&
.HYDROLOGY...
With a frontal boundary expected to linger over or near the
area, with multiple waves of low pressure passing through,
periods of moderate to locally heavy rain will be possible
through the week. At this time, the risk of flash flooding is
low, but can not be ruled out. The WPC has outlined the entire
area in a marginal risk of excessive rainfall for Tuesday
through Friday. Instances of minor urban and poor drainage
flooding are more likely.
The first period of moderate to locally heavy rain will be tonight.
The highest totals are expected to be across eastern Long Island and
southeastern CT (on average 0.5 to 1 inch). With pwats near 2
inches, localized rates of 1 inch per hour are possible.
Tuesday night into Wednesday looks to be the next period of moderate
to locally heavy rainfall. Uncertainty increases thereafter, with
the potential for another wave Wednesday night.
&&
.TIDES/COASTAL FLOODING...
-- Changed Discussion --
There is a moderate risk of rip current development at the ocean
beaches today and Tuesday. Today, a 10 kt southerly wind combines
with a 2 to 3 ft S/SE swell at 10 seconds. The swell lingers for a
bit, mainly lowering to 2 ft, on Tuesday. A shorter period wave
system builds in later on Tuesday around 3 to 4 ft at 7 seconds.
Minor coastal flood benchmarks may just be touched at some
locations along the western south shore bays of Nassau and
Queens tonight. Tuesday night has trended down and water levels
will likely stay below minor.-- End Changed Discussion --
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
CT...None.
NY...None.
NJ...None.
MARINE...None.
&&
$$
SYNOPSIS...JP/JT
NEAR TERM...JT
SHORT TERM...JT
LONG TERM...JP
AVIATION...JP
MARINE...JP/JT
HYDROLOGY...JP/JT
TIDES/COASTAL FLOODING...JT