214
FXUS61 KOKX 292002
AFDOKX
Area Forecast Discussion
National Weather Service New York NY
402 PM EDT Mon Jul 29 2024
.SYNOPSIS...
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The area remains in between broad high pressure offshore and broad
low pressure to our west. A warm front approaches the area Tuesday
night. A series of weak fronts then move through the area
Thursday through Sunday.-- End Changed Discussion --
&&
.NEAR TERM /UNTIL 6 AM TUESDAY MORNING/...
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The upper level low continues to spin just north of the area the
rest of this afternoon and then heads into northern New England
tonight. The associated surface low has been absorbed by
broader low pressure to our west. The area will remain in
between this broad low pressure and broad high pressure
offshore. This will result in persistent S/SW flow over the
whole area and in turn increasing moisture.
The area has been able to destabilize given the increasing moisture
and heating under the upper level low. Latest SPC mesoanalysis
shows about 1000 to 2000 J/kg of SBCAPE. Numerous showers and
thunderstorms have developed, especially along a Sound breeze
across the northshore of Long Island. This activity has now
moved to the southshore. The last few runs of the HRRR do not
show additional development behind the current activity.
However, isolated to scattered activity can not be completely
ruled out for the rest of this afternoon and evening.
With a moist profile, some training and slow moving storms, some
locations have observed rainfall rates around 2-2.5 inches an
hour. The main concern is minor urban and poor drainage
flooding, however, with the potential for a stronger shower or
thunderstorm to move over the NYC/NJ metro area, WPC has pulled
the marginal risk of excessive rainfall farther north. Flash
flooding can not be completely ruled out, but this threat has
lowered with this update given the current radar trends.-- End Changed Discussion --
&&
.SHORT TERM /6 AM TUESDAY MORNING THROUGH TUESDAY NIGHT/...
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The pattern continues on Tuesday with high pressure offshore and low
pressure west of the area. Moisture will continue to increase with
the latest 12z NAM and GFS showing pwat values of 1.75 to 2.00
inches by the late afternoon. Aloft, the upper level low continues
to pull away to the north while brief height rises give way to a
shortwave trough Tuesday night.
Scattered showers and thunderstorms are possible once again. PoPs
increase through the day and peak overnight as that will be when the
shortwave is moving through aloft. With less shear tomorrow, there
is less of a concern for any storms organizing and becoming severe.
However, heavy downpours are possible again in any stronger showers
or thunderstorms.
Winds increase this afternoon, especially for western areas. The
surface pressure gradient increases as well as well as a low level
jet developing off the NJ coast and eventually extending north. Some
25 to 35 mph gusts are possible in the afternoon.-- End Changed Discussion --
&&
.LONG TERM /WEDNESDAY THROUGH MONDAY/...
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Key Points:
* Multiple rounds of showers and thunderstorms possible mid week
into the weekend.
* 95 to 100F heat indices possible Thu thru Sun, particularly for
northeastern New Jersey, the lower Hudson Valley, New York City,
and portions of northwestern Long Island and SW CT.
An active upper flow through the period, with area on northern
periphery of SW/SC US upper ridging and Bermuda upper ridging. More
distinct features are northern shortwave troughing approaching on
Wed and gradually sliding east on Thu. Brief shortwave upper ridging
on Friday, followed by the next northern shortwave/closed low
digging into the Great Lakes/Ohio valley Thu Night/Friday before
gradually shearing through the NE through the weekend.
Surface trough approaches Wed AM, with ongoing shower/embedded tsra
activity coincident with theta-e rich and marginally unstable
airmass advecting in on 35-40 kt llj. This activity likely slides
east through the morning as the initial trough moves east. This
trough will likely be replaced by a subsequent
approaching/developing trough with potential for additional
scattered shower/tstms activity in aft/eve, particularly across
areas from NYC and N&W.
Low/mid level environment gradually dries out Wed Night Into Thu in
wake of this trough. Upper troughing remains on Thursday, with
surface trough approach/development once again Thu aft. A drying
airmass on deep westerly flow should limit instability and moisture,
keeping shra/tsra activity limited. Heat should begin building on
Thu with deep mixing and downslope flow, with more in the way of
sunshine. Highs in the upper 80s to lower 90s, with heat indices in
the lower to mid 90s.
Shortwave ridging surface/aloft on Friday should allow for heat and
humidity to continue to build, before potential for late day/evening
shra/tsra activity with approaching convectively enhanced shortwave
energy ahead of deepening Great Lakes/Ohio Valley upper low.
Thursday and Friday could be the hottest air temps of the period
with westerly flow aloft and deep mixing, with widespread highs in
the upper 80s to lower 90s likely, and possibly running as high as
the lower to mid 90s away from south coasts. Heat indices in the
lower to mid 90s, with upper 90s for NYC/NJ metro and Lower Hud.
Weakening mean upper troughing Saturday into Sunday as Great
Lakes/Ohio Valley trough shears NE. Lead shortwave and trough axis,
along with surface troughs moving across the area will continue
potential for aft/eve shra/tsra activity. Air temps may not be as
high for the weekend with approaching troughing, but a deepening
southerly flow will likely allow for a moistening profile and TDs
increasing. So net result would likely be continued widespread heat
indices in the lower to mid 90s, with upper 90s for NYC/NJ metro and
Lower Hud, and surroundings.
Heat advisories may be needed Thu into Sun with the possibility of
multiple days reaching heat indices of at least 95 degrees across at
least northeastern New Jersey, the lower Hudson Valley, New York
City, and portions of northwestern Long Island and SW CT. There will
be little relief at night as temperatures are expected to be several
degrees above normal, in the lower and mid 70s.-- End Changed Discussion --
&&
.AVIATION /20Z MONDAY THROUGH SATURDAY/...
An upper level low over the area will linger over New England
today, with a weak inland surface trough in its wake.
Tstms are now E of the NYC metros and impacting KISP with IFR
vsby and gusty winds. Storms there should end around or shortly
after 20Z. Outside of these storms SE-S flow 10 kt or less
prevails with mainly VFR cond, and winds at the coastal
terminals especially KJFK may increase to 10-15 kt late today
for a time before sunset.
S flow 10 kt or less expected tonight, with MVFR cigs late
tonight into the early daylight hours for the NYC metros.
Outlying terminals are more likely to go IFR/LIFR during that
time.
S winds should start to increase as cigs lift during Tue
morning. Expect speeds 10-15G20kt at some terminals by
afternoon.
...NY Metro (KEWR/KLGA/KJFK/KTEB) TAF Uncertainty...
AMD possible for winds deviating from fcst.
OUTLOOK FOR 18Z TUESDAY THROUGH SATURDAY...
Tuesday afternoon and Wednesday: Numerous showers/tstms
expected. For the coastal terminals, S winds G20-25kt
possible, along with MVFR/IFR cigs in low stratus overnight/AM.
Wednesday night and Thursday: VFR.
Friday and Saturday: Chance of MVFR or lower in
afternoon/evening showers/tstms.
Detailed information, including hourly TAF wind component
forecasts, can be found at: https:/www.weather.gov/zny/n90
&&
.MARINE...
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A Small Craft Advisory is in effect from 6PM this evening
through 6AM Wednesday morning. Winds and seas increase tonight,
with 20 to 25 kt gusts and 5 ft seas. Seas may lower to 4 ft
tomorrow, but gusts could continue. Highest gusts are likely for
the western ocean zone, with 25 to 30 kt possible. This is due
to stronger low level through and tighter pressure gradient.
Seas build back to 5 ft for Tuesday night.
Marginal SCA ocean seas likely to continue Wednesday in persistent S
flow with potential for occasional SCA gusts. Sub SCA conditions
likely return Thu into Fri with weak pressure gradient.
An increasing and persistent south to southwest flow may allow for
ocean seas to build to SCA levels later Saturday into Sunday.-- End Changed Discussion --
&&
.HYDROLOGY...
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Any remaining isolated flood threat is mainly confined to Long
Island as heavy showers and thunderstorms are currently moving
through. Chances for additional showers and thunderstorms to
move through the NYC/NJ metro area have lowered, but can not be
completely ruled out. Any stronger storm could produce heavy
downpours.
Multiple rounds of showers and thunderstorms are possible Tuesday
into Wednesday and again this weekend. Low predictability on
specific hydrologic impacts this far out. While widespread flood
impacts are not expected, localized urban and poor drainage flood
impacts are possible.-- End Changed Discussion --
&&
.TIDES/COASTAL FLOODING...
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High risk of rip currents Tonight through Wednesday with 15 to 20 kt
southerly flow and 5-6ft@7 sec periods swells.-- End Changed Discussion --
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
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CT...None.
NY...None.
NJ...None.
MARINE...Small Craft Advisory until 6 AM EDT Wednesday for ANZ350-353-
355.-- End Changed Discussion --
&&
$$
SYNOPSIS...JT/NV
NEAR TERM...JT
SHORT TERM...JT
LONG TERM...NV
AVIATION...BG
MARINE...JT/NV
HYDROLOGY...JT/NV
TIDES/COASTAL FLOODING...