000
FXUS61 KOKX 071620
AFDOKX
Area Forecast Discussion
National Weather Service New York NY
1220 PM EDT Fri Jul 7 2023
.SYNOPSIS...
A weak cold front approaches from the west today and stalls over
or near the area through the weekend. A wave of low pressure
develops along the front over the Mid Atlantic states on Sunday
and tracks across the area Sunday night into Monday. High pressure
will then build behind the system through the middle of next
week.
&&
.NEAR TERM /THROUGH TONIGHT/...
-- Changed Discussion --
A pre-frontal trough situated just west of the CWA across
upstate NY and eastern PA has initiated a line of convection
late this morning and early afternoon. SPC mesoanalysis
indicates 1000-1500 J/kg of MLCAPE NW of the NYC metro. Bulk
shear is weak and no greater than around 20 kt. Steering flow is
weak and the convection is moving slowly eastward. If the
convection survives into Orange Count or the NW interior,
locally heavy rainfall and some flooding is possible. An
isolated pulse severe storm cannot be ruled out, but think this
is a limited occurrence due to weak shear and overall weak
forcing.
CAMs have been struggling with this line, but it is possible it
makes its way towards the I-95 corridor in NE NJ and Hudson
River Corridor before dissipating this evening. Have updated
PoPs to reflect this potential this evening. The weak cold front
is still further west, but should start to near the region this
evening. This could keep some isolated-scattered convection
going towards sunset before diminishing by or around midnight.
It will be a bit cooler today with more of a maritime influence
as winds take on a bit more of easterly component from the SE.
However, while temperatures will be close to seasonable, high
humidity (dew points around 70) will make it feel uncomfortable
with heat indices around 90 for most locations if not a bit
higher.
Low clouds/patchy fog also possible tonight, especially eastern
LI/SE CT where the trajectory of warm, humid air traverses some
cooler waters. Lows will generally be in the upper 60s to lower
70s Saturday morning. However, metro NYC will be closer to 75.
This is about 5 degrees above normal.-- End Changed Discussion --
&&
.SHORT TERM /SATURDAY THROUGH SUNDAY/...
A persistence type of forecast will be on tap Saturday with
more humid weather and seasonable temperatures. Once again,
convection will be scattered and mainly to the north and west
of the NYC metro.
It gets a lot more interesting on Sunday though as shortwave
energy at the base of a longwave trough over eastern Canada
into the Ohio Valley states approaches the area. A stalled out
boundary near western sections of the forecast area and frontal
wave development over the Mid Atlantic states will interact with
high PWAT air (around 2 inches) to produce showers and thunderstorms
across the area Sunday into Sunday night. There are discrepancies
in the placement of the highest rainfall between the global
scale models and the CAMs have not quite come into the picture
yet (minus the NamNest). The latter will have to be watched as
we move into their time range. The GFS is the most bullish with
an axis of 3 to 5 inches of rainfall from metro NY/NJ up into
eastern portions of the Lower Hudson Valley and western CT.
However, the ECMWF is much farther west (Orange County NY) with
the heaviest rainfall axis and has less rainfall. Bottom line,
PWATs near record highs interacting with a frontal boundary and
some semblance of a frontal wave/frontogenesis has to be
watched.
Using a blend of the NBM with WPC QPF yields an area of 2 inch
rainfall from NYC and points north and west. WPC has placed much
of the area under a slight risk for excessive rainfall, with the
exception of eastern LI/SE CT, which are under a marginal risk.
Sunday also looks to be cooler due to an increase in cloud cover
and increasing rain chances.
&&
.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
The low pressure system and frontal system look to slowly move
out of the area on Monday. High pressure then looks to build
back in by Tuesday and into Wednesday, with a slight warming
trend toward the end of the week.
Given the pattern, high temperates will remain near or slightly
below normal for the period in the low to mid 80s.
&&
.AVIATION /16Z FRIDAY THROUGH TUESDAY/...
Weak high pressure pushes further offshore today.
Still have some terminals with MVFR stratus late this morning.
The MVFR stratus is forecast to scatter out early this
afternoon. Otherwise, VFR conditions are forecast through this
evening outside of any showers or thunderstorms.
KEWR may experience MVFR vsby at times today as there may be some
smoke some over part of the runway due to a nearby cargo ship fire.
It is unknown how long that smoke may last at the airport.
Winds become SE and increase to around 10kt going into this
afternoon.
Chance of shra/tstm mainly NW of the city terminals late
day/evening. Best chance to see a TSRA is KSWF with lower
chances to the south and east.
...NY Metro (KEWR/KLGA/KJFK/KTEB) TAF Uncertainty...
Amendments possible for improving flight categories due to low
stratus burning off which could be 1 to 2 hours off from TAF.
KLGA Sound breeze from NE may last 1-2 hours longer than
forecast.
OUTLOOK FOR 12Z SATURDAY THROUGH TUESDAY...
Saturday: MVFR possible early. Mainly VFR. Chance of
thunderstorms for all terminals in the afternoon into early
evening Saturday.
Sunday and Monday: MVFR possible with a chance of showers. A chance
of thunderstorms, mainly afternoon into early evening.
Tuesday: Becoming VFR.
Detailed information, including hourly TAF wind component forecasts,
can be found at: https:/www.weather.gov/zny/n90
&&
.MARINE...
Potential for areas of fog, especially for the eastern nearshore
and ocean waters in the coming nights will continue to be a
possibility. However, confidence in occurrence is not high at
this time.
Otherwise, conditions remain below SCA criteria through the
weekend with a weak pressure gradient over the area.
&&
.HYDROLOGY...
-- Changed Discussion --
No widespread hydrologic issues are expected through Saturday.
Brief heavy downpours, mainly across portions of the Lower
Hudson Valley and interior NE NJ, could produce localized flash
flooding late this afternoon into early this evening. The
threat is mainly confined to Orange County.
A more significant flood threat is possible Sunday into Sunday
night with the potential for the south to north training of
showers and thunderstorms along a slow moving frontal system.
Right now, then main threat for flooding appears to be from NYC
and points north and west.-- End Changed Discussion --
&&
.TIDES/COASTAL FLOODING...
For today and Saturday, there is a low risk of rip current
development for all ocean beaches. Some guidance does show a 2
ft 9-10s SE swell moving in late today that could increase the
rip current risk to moderate, though it looks largely later on
tonight/early Saturday.
Have issued a coastal flood statement for southern Nassau county
for tonight`s high tide. A few of the most vulnerable locations
may see water levels touch minor benchmarks.
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
CT...None.
NY...None.
NJ...None.
MARINE...None.
&&
$$
SYNOPSIS...DW
NEAR TERM...DS/DW
SHORT TERM...DW
LONG TERM...DBR
AVIATION...JM/MW
MARINE...DBR/DW
HYDROLOGY...DBR/DW
TIDES/COASTAL FLOODING...