110
FXUS61 KOKX 182049
AFDOKX
Area Forecast Discussion
National Weather Service New York NY
449 PM EDT Sun Aug 18 2024
.SYNOPSIS...
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A frontal system with its associated low pressure center continues
to approach the area tonight. The central low moves slowly
within the region Monday, shifting east of the area by early
Monday evening. The frontal system continues to shift east of
the region Monday night into Tuesday morning. High pressure
builds in thereafter through the remainder of the week.-- End Changed Discussion --
&&
.NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
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Heavy showers have been frequent across southwest Connecticut
where there has already been significant flooding within parts
of that area. Low level jet has really helped fuel these showers
at times exhibit close to 40-45 kt out of the south. This is
approximately 20-25 kt higher than what large scale models were
conveying.
More showers as well as thunderstorms are in the forecast, set
to move into the region across the western half this evening,
generally between 6PM and 10PM. After that, the showers and
thunderstorms are expected to weaken partially as they move
farther east across the eastern half of the region late this
evening into the overnight. Instability will be lowering from
early to late this evening.
Thunderstorms expected to be more isolated in coverage for the
eastern half of the region with less instability.
Mid level trough approaches from the west resulting in roughly a
20 meter drop with the 500mb height. Models are showing
multiple areas of higher positive vorticity advection traversing
the local area.
With this forcing and forecast increase of bulk shear 0-6 km AGL
as well as some helicity increase in low levels, there is
potential for severe weather this evening. A severe
thunderstorms watch is in effect for NE NJ, the Lower Hudson
Valley and NYC, including NY Harbor, until 10PM this evening.
Main threats in addition to the heavy rain are damaging winds.
Also, a brief isolated tornado cannot be ruled out. The low
level SE flow will help increase the low level helicity.
The central low associated with the frontal system is expected to
move east and near the western edge of the forecast region to start
the overnight period. The central low and associated occluded front
make their way into the area going into daybreak Monday.
The low and upper level forcing will make for more widespread
showers, which will be heavy at times. Layer precipitable water
maximizes across the local region tonight, reaching almost to
near 2 inches.-- End Changed Discussion --
&&
.SHORT TERM /6 AM MONDAY MORNING THROUGH MONDAY NIGHT/...
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Mid level trough continues to approach with its axis arriving within
the region by early Tuesday. About another 30 meter drop with the
500mb height is expected within the region. Once again, multiple
areas of higher positive vorticity advection move across the area
for Monday and Monday night. Vertical forcing will remain in place
to easily allow for the development of showers.
The numerical weather prediction models convey low pressure
passing east of the area early Monday, followed by a cold front
slowly moving across for afternoon into early evening. They are
coherent in their model solutions showing the low pressure
moving east of the area Monday night.
The rain on Monday could very well be more intermittent with more
lulls in the activity. However, thinking here that numerous
showers will pop up and develop throughout the afternoon with a
lingering frontal boundary acting as a focus for low level
convergence. Although the axis of higher precipitable waters is
forecast to be more east of the region, heavy rain will still be
possible at times.
Regarding thunderstorms, low level CAPE forecast to be more, up to
near or a little above 1000 J/kg, so more potential. Will
include chance of thunderstorms. Enough factors to have more
than just slight chance or isolated thunderstorms. Lowering
chances for showers and thunderstorms Monday night, mainly dry
overnight into early Tuesday morning.-- End Changed Discussion --
&&
.LONG TERM /TUESDAY THROUGH SUNDAY/...
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After a secondary frontal passage, any residual showers across S CT
and Long Island should end in the morning. This will set the stage
for drier and cooler conditions to take hold into midweek. Behind
the fropa, high temps on Tuesday could be some of the coolest since
late May, generally in the upper 60s to mid 70s.
The drier, cooler pattern will continue into mid week behind the
frontal system as dry air advects south, with surface high pressure
building in. Lingering upper trough over the Northeast may persist
into late week, reinforced by a closed low dropping south out of
Canada.
This high will be accompanied with primarily N-NW winds and a much
cooler regime. Highs temps Wed will be in the 70s, with low temps
Wed AM and Thu AM in the 50s to near 60. Some interior spots as well
as in the Long Island Pine Barrens could bottom out in the upper 40s
by daybreak Thu depending on the strength of any radiational
cooling. Temperatures will gradually moderate into late week and the
weekend with highs reaching the upper 70s to lower 80s by Fri, and
well into the 80s next weekend.-- End Changed Discussion --
&&
.AVIATION /20Z SUNDAY THROUGH FRIDAY/...
A frontal system slowly approaches the terminals through
tonight, with a wave of low pressure and cold front passing
through Monday morning.
MVFR, with breaks of VFR at the NYC metro terminals. There is a
chance of IFR east of the NYC terminals. Scattered showers and
an isolated thunderstorm will east of the NYC terminals through
the afternoon. Another round of showers and thunderstorms is
likely by early this evening, with a few of the thunderstorms
possibly producing strong gusty winds. Also, periods of moderate
to heavy rainfall will be likely with any of the showers and
thunderstorms. Showers will be continuing through tonight, and
then taper off toward Monday morning. Low confidence with timing
of flight category changes and with timing and areal coverage of
showers and thunderstorms this evening.
Winds will be S to SE through tonight, with gusts 17kt to 24kt
this afternoon, more likely at the NYC metro terminals. Winds
begin to shift toward the SW during Monday morning.
...NY Metro (KEWR/KLGA/KJFK/KTEB) TAF Uncertainty...
Low confidence forecast with timing of flight category changes
and timing/areal coverage of showers and thunderstorms. A few
strong thunderstorms are possible late this afternoon and this
evening with gusty winds possible.
S to SE winds will be gusty, with gusts 17kt to 24kt at times,
with the gusts ending early this evening.
OUTLOOK FOR 18Z MONDAY THROUGH FRIDAY...
Monday afternoon: Generally VFR. Scattered showers and
thunderstorms with MVFR or lower at times.
Tuesday: Mainly VFR. A chance of showers, mainly in the
morning, with MVFR possible. NW wind gusts 15-20 kt.
Wednesday-Friday: VFR.
Detailed information, including hourly TAF wind component forecasts,
can be found at: https:/www.weather.gov/zny/n90
&&
.MARINE...
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Rough ocean seas and long period swells remain through tonight
and into Monday. Seas decrease more Monday afternoon into Monday
night. SCA for ocean remains in effect for the ocean through
Monday night.
Winds are expected to remain below SCA thresholds outside of
thunderstorms. Non-ocean zones are expected to remain below SCA
thresholds for winds and seas through Monday night.
The rough ocean seas and long period swells come from distant
tropical cyclone Ernesto as it passes well northeast of the
area in the open Atlantic. This is also leading to rough
conditions around inlets. Please refer to the National Hurricane
Center for official forecasts regarding Ernesto.
Thereafter, elevated wave heights on the ocean zones will allow
for SCA conditions to possibly continue into the day on
Tuesday. By Late Tuesday, wind diminish and wave heights should
fall below 5 feet. Sub-SCA conditions are then expected with
high pressure moving into the area by midweek.-- End Changed Discussion --
&&
.HYDROLOGY...
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Flood watch remains in effect for NE NJ, Orange and Rockland NY
and has been expanded to include Putnam NY, Westchester NY as
well as Fairfield CT and New Haven CT. The expansion is because
this area has had a lot of heavy rain showers already with more
on the way this evening. Fairfield CT has already had locations
experience significant flooding.
The flood watch goes until 2AM Monday.
Across the rest of the forecast region, NYC, Long Island, SE
Connecticut, not as much rain has fallen, and timing of most
shower and thunderstorms is expected to be when convection is
weakening limiting the flood threat. However, localized flash
flooding cannot be ruled out.
Additional rain Monday into Monday night looks be more
temporally and spatially limited, with just a marginal flash
flood threat. Otherwise, minor flooding in low lying and poor
drainage areas.
Rainfall totals are near 0.75 to 1.25 for much of the area with
locally higher totals, much higher for SW Connecticut through
Monday night. Bulk of the rain expected through this evening.
No hydrologic concerns expected thereafter Tuesday through next
weekend.-- End Changed Discussion --
&&
.TIDES/COASTAL FLOODING...
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A high rip current risk is in place through Monday due to elevated,
long period swells from Ernesto.
Ocean seas are forecast to be highest through Monday, and with surf
heights up to 6 ft, local beach erosion is possible.
A full moon on Monday as well as swell from distant Ernesto will
also elevate total water levels this week. Have continued the
advisory for the back bays of Nassau and Western Sound along the
southwest CT and S Westchester coast for this evening`s high tide,
and the statement for areas along Jamaica Bay and lower NY Harbor.
Additional minor flooding is possible with the high tide cycles
(especially the evening/nighttime cycles) through much of this week.
Additional advisories/statements will likely be needed.-- End Changed Discussion --
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
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CT...Flood Watch until 2 AM EDT Monday for CTZ005-006-009-010.
Coastal Flood Advisory from 10 PM this evening to 1 AM EDT
Monday for CTZ009.
NY...Flood Watch until 2 AM EDT Monday for NYZ067>071.
Coastal Flood Advisory from 10 PM this evening to 1 AM EDT
Monday for NYZ071.
High Risk for Rip Currents through Monday evening for NYZ075-080-
081-178-179.
Coastal Flood Advisory until 10 PM EDT this evening for NYZ179.
NJ...Flood Watch until 2 AM EDT Monday for NJZ002-004-006-103>108.
MARINE...Small Craft Advisory until 6 AM EDT Tuesday for ANZ350-353-355.-- End Changed Discussion --
&&
$$
SYNOPSIS...BG/JM
NEAR TERM...JM
SHORT TERM...JM
LONG TERM...BG
AVIATION...MET
MARINE...JM/MW
HYDROLOGY...JM
TIDES/COASTAL FLOODING...BG