809
FXUS61 KOKX 092226
AFDOKX
Area Forecast Discussion
National Weather Service New York NY
626 PM EDT Tue Jul 9 2024
.SYNOPSIS...
A stalled frontal boundary lifts north as a warm front late tonight
into Wednesday. The remnants of Beryl will approach on Wednesday,
and then lift north of the area while dragging a cold front through
Wednesday night into Thursday. The frontal boundary stalls and
remains over the area Friday into Saturday, then high pressure
will be in control for Sunday. Early next week will feature
weak high pressure with nearby surface troughs.
&&
.NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/...
-- Changed Discussion --
Adjustments made mainly to PoPs with this update early this
evening based on latest radar obs.
Showers a few embedded thunderstorms have been developing over
eastern PA into NJ, but are having a difficult maintaining
strength as they head into the forecast area. Meanwhile,
activity developing to the north of the forecast area will be
pushing ENE. Probably not much that develops in our forecast
area, mainly just a case where ongoing cells manage to drift
over here.
There will be low stratus and some fog pushing across southern
most zones from the ocean waters, and possibly getting into CT
coastal zones tonight. Some reduced visibilities are a possible
across south and eastern coastal zones of LI and CT.
For tonight area it will be another very warm and muggy night.
Temperatures continue to average well above the seasonal night time
normals.-- End Changed Discussion --
&&
.SHORT TERM /6 AM WEDNESDAY MORNING THROUGH THURSDAY NIGHT/...
For Wednesday look for another hot and humid day. A southerly wind
increases through the afternoon, especially closer to south facing
shorelines. This will bring in even higher dewpoints to some effect
for these southern and eastern zones. The region will have some haze
and fog further south and east in the morning, but should burn off
with temperatures climbing more so for the early afternoon.
Temperatures and heat indices should be similar to the previous day,
with Heat advisories continuing for all areas into Wednesday. Going
through the next couple of days any capping should gradually weaken.
Thus the chances for isolated to scattered shower and t-storm
activity increases. PWATs will be in anomalously high
territory, mainly above 2, and possibly 2.25 inches. Thus the
primary impact from any t-storms would be heavy rain. Any storm
could put down 1 to 2 inches locally in a short period of time.
The relatively higher chance of this for late Wed and Wed eve is
to the N and W of NYC.
The remnants of Beryl draw closer Wed night, but the axis of the
tropical moisture plume belonging to Beryl should push west, then
north of the area late Wed night into Thursday. The cold front
extended south from the remnants of Beryl will get on top of the
area early Thu AM. This will be the best chance at seeing more
widespread rainfall as many CAMs are brining through a line of
showers with embedded t-storms. A limiting factor could be the line
coming through late and night and into Thu AM and not coinciding
with daytime heating. In any event WPC maintains a marginal risk of
excessive rainfall for a good portion of the area for this time
period. See hydro section of this AFD for more details regarding
uncertainty and potential impacts.
During Thursday expect the cold front to slowly push through. There
remains uncertainty as to ultimately how far east it gets later
Thursday and Thursday night. Expect scattered shower and t-storm
activity during the day Thursday. How far east the front gets
will determine whether any axis of heavy rain from localized
storms sets up. Some guidance indicates the axis of heavier rain
could fall further east for eastern sections, but this remains
rather uncertain at this time. With more cloud cover on average
due to the proximity of the front look for temperatures perhaps
to be a couple degrees cooler overall, thus despite elevated dew
points it appears that much, if not all of the area may remain
just below heat advisory criteria. Thus, have not extended heat
advisories into Thursday as of yet. Subsequent shifts can issue
an extension in time if things shift warmer. Relatively higher
PoPs are centered around Wed evening through the first half of
Thursday. Primarily maintained chance to slight chance PoPs into
Thursday afternoon and night. Dewpoints are not quite as high
later Thu and Thu night, but still rather elevated with mainly
upper 60s and lower 70s dew points, so still rather humid.
&&
.LONG TERM /FRIDAY THROUGH TUESDAY/...
A stalled frontal boundary is progged to remain over or near the
western portion of the forecast area Friday and Friday night.
Surface based lift will be limited, however mid-level lift from
shortwave energy arriving from the SW will tap into a moist
atmosphere and help bring the likelihood of showers for a good
portion of the area. Additional lift may arrive in the form of a
shortwave moving clockwise around the periphery of a western
Atlantic ridge. Both areas of lift aloft should lose influence
by the end of the night. Shear is fairly weak, so severe
thunderstorms are not anticipated at this time. However,
scattered thunderstorms with downpours may bring some flooding
issues. See the hydrology section for more details.
The surface boundary weakens on Saturday as it gets pushed eastward
with the help of a shortwave/weak upper trough traveling east along
the Saint Lawrence River Valley. PoPs capped at chance, but heavy
rain still possible Saturday morning - mainly due to uncertainties
in the weather pattern this far out in time.
Sunday through Tuesday will feature weak high pressure in control.
Weak surface/thermal troughs may set up for Monday and Tuesday.
Mainly dry for the period, but there will be chances of diurnal
convective showers - mainly for Monday and Tuesday. Heat rebuilds
during this period with models showing temps at the top of the mixed
layer slowly increasing with each day. So far, models are showing
some potential for areas outside of sea breezes/onshore flow to have
surface dewpoints mix out during daytime heating with a SW-WSW
surface winds and a sufficiently dry boundary layer. This may change
as the time periods draws nearer, but for now it appears that heat
advisories will still eventually be needed for a good portion of the
forecast area Monday and Tuesday, and perhaps even on Sunday as well
for a few zones.
&&
.AVIATION /22Z TUESDAY THROUGH SUNDAY/...
A frontal boundary remains in close proximity to the area through
the TAF period.
Mostly VFR forecast. Lingering low cigs are eroding at KJFK, KISP,
and KGON at 20Z and should improve within the hour if not sooner. A
bit stronger flow tonight may help limit coverage of additional fog
and stratus development otherwise, but likely manages to redevelop
overnight at least at KGON. Widely isolated SHRA or TSRA possible
into early evening and again Wed PM, generally city terminals on
north and west, but coverage is too spotty to include at this time
with the exception of KSWF.
Winds 10 kt, with gusts toward 20 kt at NYC terminals, but these may
be more occasional at times. Flow lightens tonight, before
increasing once again out of the south 10-15 kt, with gusts above 20-
25 kt Wed afternoon.
...NY Metro (KEWR/KLGA/KJFK/KTEB) TAF Uncertainty...
Gusts today may be more occasional.
Isolated SHRA/TSRA possible late today and again Wed PM.
Cig or vsby restrictions possible overnight into Wed AM, especially
at KJFK.
OUTLOOK FOR 18Z WEDNESDAY THROUGH SUNDAY...
Wednesday Afternoon through Sunday: MVFR or lower possible at times
with periods of showers/thunderstorms.
Detailed information, including hourly TAF wind component forecasts,
can be found at: https:/www.weather.gov/zny/n90
&&
.MARINE...
Marine dense fog advisories are in effect for tonight into early
Wednesday afternoon for the ocean, and the eastern and south
shore bays of Long Island, along with the eastern most portion
of LI Sound.
Sub small craft conditions for all waters through tonight. A
southerly flow gradually increases during the day Wednesday with
small craft conditions towards the afternoon for the ocean waters
into Wednesday night. Small craft conditions will likely persist on
the ocean waters through Thursday night with 5 ft seas and gusts of
25 kt, thus a small craft advisory has been issued for this time
frame. Marginal small craft conditions are likely for the southern
and eastern most near shore waters during much of this time frame.
Advisory level seas will probably continue through Friday night due
to a lingering swell. Conditions should be sub-advisory for the
upcoming weekend, but the swell will probably keep ocean waves
averaging around 4 feet during this time.
&&
.HYDROLOGY...
With a very humid airmass locked in across the region and a
frontal boundary drawing closer for the mid and late week
period WPC maintains a marginal risk of excessive rainfall for
a good portion of the area Wednesday through Thursday night. At
any point a stronger thunderstorm could produce localized
flooding impacts.
An average of half inch to an inch of rainfall is expected Friday
into Friday night across Long Island and Southeastern CT, with an
inch to 2 inches, locally higher, westward through the Lower Hudson
Valley and NE NJ. Primarily minor urban/poor drainage small stream
flooding will be possible, but there is a low threat of flash
flooding. The better chances for flash flooding appears be across NE
NJ into parts of the Lower Hudson Valley at this time. Additional
rain chances are anticipated for Saturday, but the bulk of the
rainfall is slated for Friday through Friday night.
&&
.TIDES/COASTAL FLOODING...
-- Changed Discussion --
There is a high risk of rip current development along all ocean
beaches on Wednesday.-- End Changed Discussion --
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
-- Changed Discussion --
CT...Heat Advisory until 8 PM EDT Wednesday for CTZ005>010.
NY...Heat Advisory until 8 PM EDT Wednesday for NYZ067>075-078-
176>179.
High Risk for Rip Currents from 6 AM EDT Wednesday through
Wednesday evening for NYZ075-080-081-178-179.
NJ...Heat Advisory until 8 PM EDT Wednesday for NJZ002-004-006-
103>108.
MARINE...Dense Fog Advisory until noon EDT Wednesday for ANZ332-340-345.
Dense Fog Advisory until 2 PM EDT Wednesday for ANZ350-353-355.
Small Craft Advisory from 8 PM Wednesday to 8 PM EDT Thursday
for ANZ350.
Small Craft Advisory from 5 PM Wednesday to 8 PM EDT Thursday
for ANZ353.
Small Craft Advisory from 2 PM Wednesday to noon EDT Thursday
for ANZ355.-- End Changed Discussion --
&&
$$
SYNOPSIS...JC/JE
NEAR TERM...JE
SHORT TERM...JE
LONG TERM...JC
AVIATION...DR
MARINE...JC/JE
HYDROLOGY...JC/JE
TIDES/COASTAL FLOODING...JC