714
FXUS61 KOKX 300547
AFDOKX
Area Forecast Discussion
National Weather Service New York NY
147 AM EDT Tue Jul 30 2024
.SYNOPSIS...
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.
&&
.NEAR TERM /UNTIL 6 AM THIS MORNING/...
An anomalous upper level low will slowly drift north into New
England tonight. The associated surface low has been absorbed by
broader low pressure to our north. 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.
Localized flash flood threat has ended with waning instability,
but a couple more spokes of vorticity around the upper low and
weak warm front moving north will bring isolated shower
activity across mainly CT and LI tonight.
Increasingly humid airmass ahead/along warm front will also
bring stratus development overnight.
Warm and muggy conditions overnight, with lows in the upper
60s/lower 70s.
&&
.SHORT TERM /6 AM THIS MORNING THROUGH 6 PM WEDNESDAY/...
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.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/...
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.
&&
.AVIATION /06Z TUESDAY THROUGH SATURDAY/...
-- Changed Discussion --
An upper level low will linger over New England today. A weak
surface trough approaches Tuesday night.
Southerly flow 10 kt or less expected early this morning, with
MVFR cigs possibly between 08-14z, especially for terminals
outside of NYC. Some of these terminals may even fall to
IFR/LIFR.
Cigs increase back to VFR around 14-16z, and the southerly flow
will increase with speeds 10-20G20-30kt. The strongest gusts
will be at KJFK/KLGA.
Confidence not high for thunder at the terminals Tuesday
afternoon, so removed any mention. Will include PROB30s for rain
after 00z Wednesday. Uncertainty still whether or not there will
be any thunder after 00z. This will need to be monitored.
...NY Metro (KEWR/KLGA/KJFK/KTEB) TAF Uncertainty...
AMD possible for winds deviating from fcst. Start and end time
of gusts may be off by an hour or two.
Removed mention of tsra in the forecast for Tuesday afternoon
with confidence low of occurrence. Better chances for TSRA
remain west of the terminals.
OUTLOOK FOR 06Z WEDNESDAY THROUGH SATURDAY...
Tuesday night and Wednesday: showers possible after 00z
Wednesday, along with MVFR/IFR cigs in low stratus
into Wednesday morning. Chance low cigs continue into Wednesday
afternoon.
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-- End Changed Discussion --
&&
.MARINE...
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. Conds may briefly lower to
sub SCA late tonight/Tue AM, before building once again Tue
aft. 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. SCA gusts expected for the south shore bays
during this time as well.
Marginal SCA ocean seas likely to continue into 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.
&&
.HYDROLOGY...
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.
&&
.TIDES/COASTAL FLOODING...
High risk of rip currents Tonight through Wednesday with 15 to 20 kt
southerly flow and 4-6ft@7 sec periods swells.
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
-- Changed Discussion --
CT...None.
NY...High Risk for Rip Currents through Wednesday evening for NYZ075-080-
081-178-179.
NJ...None.
MARINE...Small Craft Advisory from 11 AM this morning to 2 AM EDT
Wednesday for ANZ345.
Small Craft Advisory until 6 AM EDT Wednesday for ANZ350-353-
355.-- End Changed Discussion --
&&
$$
SYNOPSIS...JT/NV
NEAR TERM...JP/JT/NV
SHORT TERM...JT
LONG TERM...NV
AVIATION...BC
MARINE...JT/NV
HYDROLOGY...JT/NV
TIDES/COASTAL FLOODING...