000
FXUS61 KOKX 212359
AFDOKX
Area Forecast Discussion
National Weather Service New York NY
759 PM EDT Fri Jul 21 2023
.SYNOPSIS...
-- Changed Discussion --
Cold front pushes east of the region tonight. Weak high
pressure gradually pushes into the region for the weekend and
remains in control through late next week.-- End Changed Discussion --
&&
.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
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Broad upper troughing remains over the Northeast into tonight,
with trough axis pivoting through the region early this evening.
At the surface, resultant low pressure tracks along the Saint
Lawrence River Valley, with a weak cold front extending south
through the NY/CT border and into NYC metro, expected to swing
through the area by midnight.
Severe threat over SE CT expected to come to an end over the
next hour, as line segment of strong/severe thunderstorm over
New Haven County slowly slides SE with potential for some
additional locally strong tstm development downstream across
far SE Ct and perhaps north fork of LI through this evening.
Elsewhere, drier airmass in wake of cold front and south of sea
breeze boundaries should limited any activity to weak and
isolated as little vertical development has been noted thru
early evening.
Conditions dry out overnight behind cold frontal passage as the
flow turns WNW behind the fropa. Temperatures bottom out in the
60s by daybreak Saturday, with noticeably drier airmass
advecting in.-- End Changed Discussion --
&&
.SHORT TERM /6 AM SATURDAY MORNING THROUGH SATURDAY NIGHT/...
Upper troughing lingers but drier conditions greet us to start the
weekend, as weak surface high pressure builds in from the west
behind the fropa.
Dew points should drop a tad from previous days with the light WNW
flow, though likely still in the low to mid 60s, with afternoon
highs close to seasonal normals, in the low to mid 80s. Sunshine
prevails with a bit of mid-level cu at times.
Mostly clear skies and light winds Saturday night may allow some of
the far interior and LI Pine Barrens to drop into the 50s overnight,
with the remainder of the region in the 60s. A consensus of MOS
guidance was used for temperatures Saturday night to account for
this.
&&
.LONG TERM /SUNDAY THROUGH FRIDAY/...
The flow aloft will be slightly cyclonic on Sunday with weak high
pressure at the surface. Dry weather and not so muggy with afternoon
dewpoints falling into the upper 50s to lower 60s. High temperatures
will be near normal. For Monday, the flow aloft becomes more
cyclonic, and with boundary-layer dewpoints a little higher this
time, CAPEs will also be higher. Might not take much supplemental
mechanical forcing for diurnal convection to pop up as capping
appears to be weak. Best chances would be from around the city to
points north and west. The flow aloft should be weak, so a limited
severe wx threat in any pulse-type thunderstorms. More of the same
for Tuesday as the axis of the trough aloft moves closer to us. This
axis is progged to shift through during Wednesday, however in a
dampened state. So with more of a flatter flow aloft and stronger
capping beneath, only isolated showers and thunderstorms possible NW
of the city. High temperatures for both Tuesday and Wednesday
remaining near normal.
The flat flow aloft holds for Thursday and Friday with some models
suggesting a shortwave moving through or nearby during Friday into
Friday night. Will go with a dry forecast for Thursday, then low
chances of showers and thunderstorms for Friday. Temperatures at the
top of the boundary layer rise through this period. So in the
absence of significant cloud cover, highs on Thursday average around
90. Even hotter for Friday based on progged 850mb temps of 18-20C.
75th percentile NBM for highs are possible, but with this being a
week away, will go with the cooler deterministic NBM for now. The
first heat advisories of the season may be needed for the Thursday-
Friday period.
&&
.AVIATION /00Z SATURDAY THROUGH WEDNESDAY/...
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Cold frontal passage this evening. Weak high pressure will
follow thereafter into Saturday.
Tstm threat over KBDR will come to an end by 01z, and then KGON by
04z as cold front passes through.
VFR in its wake (except patchy IFR conds possible at KGON),
with winds shift to the west around 10 kt behind cold fropa,
and then NW 5 to 10 kt overnight. NW winds (right of 310
magnetic) around 10kt Saturday, backing W/SW for coastal
terminals with surface trough development. Sea breeze
development not likely for south coastal terminals.
...NY Metro (KEWR/KLGA/KJFK/KTEB) TAF Uncertainty...
The afternoon KJFK/KLGA/KEWR haze potential forecast is YELLOW,
which implies slant range visibility 4-6SM outside of cloud.
OUTLOOK FOR 00Z SUNDAY THROUGH TUESDAY...
Saturday Night through Sunday night: VFR.
Monday: Mainly VFR. Slight chance of a late day shower/tstm
KSWF.
Tuesday: Chance of afternoon showers/tstms with brief MVFR/IFR
vsby from the NYC metros north/west.
Wednesday: VFR.
Detailed information, including hourly TAF wind component
forecasts, can be found at: https:/www.weather.gov/zny/n90-- End Changed Discussion --
&&
.MARINE...
A Marine Weather Statement is in effect for the Long Island Sound.
The National Weather Service in coordination with the United States
Coast Guard have received reports of a large debris field across
Long Island Sound, caused by recent flooding across New England.
This will create some hazards for boaters, swimmers, and watercraft
in the affected area. The debris vary from trees, logs, coolers, and
docks and may not be easily visible.
Sub SCA conditions prevail through the weekend and into early next
week with a weak pressure gradient in place.
&&
.HYDROLOGY...
-- Changed Discussion --
Flash flood threat has come to end this evening as convection
weakens.
No significant widespread rainfall is expected from Saturday through
mid next week.-- End Changed Discussion --
&&
.TIDES/COASTAL FLOODING...
There is a moderate risk of rip currents for only eastern
Suffolk on Saturday with seas near 3 ft and weak offshore flow,
with a low rip risk elsewhere. There is a low risk of rip
currents for Sunday, with weak westerly flow and seas less than
3 ft.
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
CT...None.
NY...None.
NJ...None.
MARINE...None.
&&
$$
SYNOPSIS...JC/BR
NEAR TERM...NV
SHORT TERM...BR
LONG TERM...JC
AVIATION...BG
MARINE...JC/BR
HYDROLOGY...JC/BR
TIDES/COASTAL FLOODING...