873
FXUS61 KOKX 052043
AFDOKX
Area Forecast Discussion
National Weather Service New York NY
443 PM EDT Wed Jun 5 2024
.SYNOPSIS...
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A warm front approaches from the south tonight and lifts north
of the area Thursday morning. A cold frontal passage will follow
Thursday night. A broad area of low pressure meanders nearby
over southeast Canada Friday and into early next week. High
pressure follow for the middle of next week.-- End Changed Discussion --
&&
.NEAR TERM /THROUGH THURSDAY/...
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An approaching warm front over the Mid Atlantic states early
this evening will move across the area late tonight into Thursday
morning. A moisture-laden airmass with PWAT around 2 inches
with modest thermal forcing will produce widespread showers with
embedded thunderstorms. Latest CAMs show much of the activity
moving into western portions of the area around or just after
midnight. Rainfall rates will generally be less than 0.25"/hr
with localized higher amounts up to an inch/hr with stronger
embedded convection. Main impacts look to be minor nuisance
flooding, primarily in urban areas. Severe weather is not a
threat overnight. The bulk of the rainfall falls with the warm
front. There is also the potential for fog overnight, especially
at the coast as higher dew point air moves across the cooler
nearshore waters. However, confidence is low with SST in the mid
60s and the fact that it did not occur last night. Prefer to
see a larger difference between the SST and dew points.
Rain associated with the warm front exits far eastern LI and SE
CT by late morning. The forecast area will dry out for the
remainder of the morning into the early afternoon before
convection develops along and ahead of an approaching pre-
frontal trough. Airmass destabilizes in the warm sector with the
potential for CAPE values increasing to 1000-2000 J/KG north
and west of NYC by early afternoon, then shifting eastward
through the evening hours. The severe weather threat is low
with mid level winds around 30 kt, and CAPEs more typical of
heavy rain with slower updrafts. That being the case, should we
be able to achieve potential CAPEs in excess of 2000 J/KG, this
may be enough for a marginal severe weather. SPC has the forecast
area under a Marginal Risk with the exception of eastern LI and
SE CT. While rainfall will be heavy with any showers and thunderstorms,
storm motion will be west at 25 to 30 kt. This should limit the
flood threat to mainly the minor nuisance poor drainage variety,
but isolated flash flooding can`t be completely ruled out. The
threat ends by late evening Thursday.
Overnight lows will be in the 60s to around 70, which is above
normal by about 10 degrees. For highs on Thursday, went with the
warmer NBM guidance in the warm sector with highs in the low to
mid 80s from NYC and points north and west, and in the 70s to
around 80 elsewhere. It will be coolest along the immediate
south shore of LI.-- End Changed Discussion --
&&
.SHORT TERM /THURSDAY NIGHT THROUGH FRIDAY/...
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Any lingering convection ends by late Thursday evening for
eastern LI/SE CT. An upper low over the eastern Great Lakes
drops into the Northeast during this time with the potential for
scattered showers Friday afternoon for the interior. It will
also be a bit cooler on Friday with the exception of coastal
locations that will be able to warm up to 75 to 80 due to a
more westerly flow. WSW winds on Friday may also gusts up to 20
mph in the afternoon.-- End Changed Discussion --
&&
.LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/...
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A relatively unsettled period this weekend into early next week with
an upper low cutting off and meandering over the Great Lakes region
and southeast Canada much of the time, with multiple vorticies
rotating around it that may periodically enhance rain chances
locally.
The broad low nearby likely instigates diurnal shower activity with
varying coverage each day, especially inland. As the cold pool moves
aloft, also can`t rule out the possibility of thunderstorms with
added instability. Global guidance continues to offer differing
solutions with any potential vorticies however and this will need to
be resolved for further clarity on when rain chances will be
highest.
Temperatures, while hampered by cloud cover and rain at times,
should still manage to get into the 70s and lower 80s most
afternoons, or about typical for this time of year. For now,
continued to cap PoPs at 50%, otherwise, national blend was followed
with subtle adjustments.
After Tuesday, global guidance varies. They agree on the meandering
low finally pushing out into the open Atlantic. They disagree on
what happens afterwards with some of the guidance hinting at a
ridging pattern taking hold, while others bring in another trough
from the west.-- End Changed Discussion --
&&
.AVIATION /20Z WEDNESDAY THROUGH MONDAY/...
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High pressure shifts farther offshore this evening ahead of an
approaching warm front from the southwest. The front lifts through
the region Thursday morning, followed by a cold front Thursday
evening.
Conditions have improved to VFR for all terminals. MVFR could come
and go at KISP and KJFK this afternoon. An isolated
shower/thunderstorm has formed southwest of KEWR and is expected to
move over the terminal between 20z and 21z. Confidence is too low to
include SHRA or TSRA in any other TAF for this afternoon.
Conditions likely decline to IFR or lower once again tonight with
showers developing. Embedded thunder can`t be ruled out overnight
into Thursday morning, but chance is too low to include at this
time. Steadiest of the showers exits by mid morning Thursday, but
improvement may take until late morning or early afternoon. Another
round of showers and thunderstorms is then possible in the
afternoon. Higher confidence in thunder for this period and included
a PROB30 for TSRA.
Southerly flow persists into Thursday, speeds around 10 kt.
...NY Metro (KEWR/KLGA/KJFK/KTEB) TAF Uncertainty...
MVFR could return to KJFK before 00z.
Timing of category declines and SHRA late this evening may be off by
a few hours.
Isolated thunder possible overnight into Thursday morning.
OUTLOOK FOR 18Z THURSDAY THROUGH MONDAY...
Thursday Afternoon: MVFR or lower possible in showers and
thunderstorms.
Friday: Mainly VFR. Chance of showers and thunderstorms for KSWF.
Saturday-Monday: Chance of MVFR in showers.
Detailed information, including hourly TAF wind component forecasts,
can be found at: https:/www.weather.gov/zny/n90-- End Changed Discussion --
&&
.MARINE...
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Fog may become an issue overnight as high dew point air moves
across the waters. However, with water temps on the ocean in the
mid 60s this did not happen last night. Confidence is low at
this time.
SCA has been issued for the ocean waters for Thursday and
Thursday night for marginal Southerly gusts 20-25kt and seas
building to 4 to 6 ft. Seas around 5 ft may linger into Friday.
Conditions are expected to remain below SCA levels through the
weekend into Monday.-- End Changed Discussion --
&&
.HYDROLOGY...
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Rainfall amounts of 0.50 to 1.00" with localized higher amounts
are expected overnight into Thursday morning. Minor nuisance
poor drainage flooding will be the primary threat especially in
urban and low lying areas. The flooding potential will be
limited due to the expected speed of the showers and thunderstorms
which with a progressive pattern aloft, should be a relatively
faster steering flow.-- End Changed Discussion --
&&
.TIDES/COASTAL FLOODING...
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Have extended the ongoing Coastal Flood Advisory for coastal
Fairfield, Westchester, and S Nassau counties for this evening into
the Thu evening high tide cycle, and added the tidal waterways of NE
NJ to the coastal flood statement for this evening`s high tide
cycle. Elevated astronomical high tides associated with the new moon
combined with onshore flow will continue to support water levels
touching or just surpassing minor flood benchmarks in these areas.
It is uncertain whether the Fri evening high tide cycle will also be
impacted, as multiple high tide cycle surge events such as this can
sometimes last longer than model forecasts.
There remains a moderate rip current risk on the ocean beaches
through Friday due to building seas and a strengthening
southerly flow. There is a chance this will need to be elevated
to a high risk.-- End Changed Discussion --
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
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CT...Coastal Flood Advisory from 9 PM this evening to 1 AM EDT
Thursday for CTZ009.
NY...Coastal Flood Advisory from 9 PM this evening to 1 AM EDT
Thursday for NYZ071.
Coastal Flood Advisory until 10 PM EDT this evening for NYZ179.
NJ...None.
MARINE...Small Craft Advisory from 6 AM Thursday to 6 AM EDT Friday for
ANZ350-353-355.-- End Changed Discussion --
&&
$$
SYNOPSIS...BR/DW
NEAR TERM...DW
SHORT TERM...DW
LONG TERM...BR
AVIATION...JT
MARINE...BR/DW
HYDROLOGY...BR/DW
TIDES/COASTAL FLOODING...BG