000
FXUS61 KOKX 091238
AFDOKX
Area Forecast Discussion
National Weather Service New York NY
838 AM EDT Sat Sep 9 2023
.SYNOPSIS...
A frontal boundary remains draped near or over the region this
weekend. The front passes east of the area late Monday. Another
frontal system will likely pass by the end of the week.
&&
.NEAR TERM /THROUGH TONIGHT/...
Just a bit of patchy fog in some spots early this morning with
light southerly winds and dew pt depressions of just a few
degrees. This should erode as we move further through the
morning hours. The spotty showers and thunderstorms around in
parts of southern CT have dissipated, and the region should
remain dry for the time being. Forecast remains on track and
previous discussion follows.
H5 trough axis running from the Great Lakes down into the Southeast
will remain pegged just to the west of the region today. A weak
stationary front on the leading edge helps to instigate scattered
convection once again, particularly from NYC and points north and
west (closest to the boundary).
Daytime instability with increasing CAPE will provide an
environment conducive to convective development, with the
nearby front adding to the forcing. Hi-res CAMs prog timing
mainly in the afternoon and evening hours, though isolated
activity is possible on either side of this. SPC has a marginal
risk for severe weather outlined from NYC and points N&W. This
aligns well with where the CSU-MLP places a 5-15% risk for
isolated damaging wind gusts, which is the primary hazard from
any strong or severe storm.
Weak shear profiles could lead to training slow moving
convection, elevating the hydro threat, especially in areas that
saw rainfall on Friday. Given this, WPC has added a slight risk
for excessive rainfall across the western half of Orange Co,
and maintained the marginal risk for the remainder of the lower
Hudson Valley, NE NJ, and NYC. Locally heavy downpours could
produce nuisance flooding of urban and poor drainage areas,
with isolated to scattered areas of flash flooding not out of
the question.
Despite cooler conditions with cloud cover and onshore flow, an
abundantly moist air mass remains with PWATs above 1.5 inches,
so another humid day can be expected. Highs top out in the low
to mid 80s for most this afternoon. Dew pts in the 70s will
yield heat indices in the lower 90s at times, but should remain
below advisory criteria.
The showers and thunderstorms chances continue into tonight,
though severe threat lowers with loss of heating. Temperatures
remain mild overnight and fog will be possible once again.
&&
.SHORT TERM /SUNDAY THROUGH SUNDAY NIGHT/...
A similar setup on Sunday, as the flattening upper trough
remains just west of the region. This will keep a nearly
stationary front draped through or near the forecast area.
Given the expected cooling aloft and additional forcing with
the incoming trough, there could be an increase in convective
coverage in the afternoon and early evening hours compared with
Saturday. It will remain humid as PWATs remain in the 1.5 to 2
inch range. However, the instability will be held down some
which should mitigate the severe thunderstorm threat. The
abundant moisture content and slow movement of the convection
will maintain a flood threat. WPC added a slight risk for
excessive rainfall for Orange Co and NE NJ, with much of the
remainder of the forecast area in a marginal risk.
Overall, upwards of 1 to 1.5 inches of rainfall is expected over the
lower Hudson Valley and portions of NE NJ through the weekend,
between a 0.5 to 1 inch for NYC, and less than half an inch
elsewhere. Given the convective nature, locally higher amounts can
be expected. The showers and thunderstorms begin to shift east
with the boundary and trough Sunday night, pushing higher rain
chances into southern CT and Long Island. Generally followed
the national blend of models and the superblend of guidance for
this update.
&&
.LONG TERM /MONDAY THROUGH FRIDAY/...
No significant changes in the extended. Chances for shwrs Mon
with a humid airmass and energy embedded in an upr lvl trof.
Inland areas favored for pcpn with low lvl speed convergence in
onshore flow. Enough instability per the NAM for some embedded
tstms, so isold tstm coverage has been included Mon.
The boundary is weak but is modeled to come thru Mon ngt. The flow
then quickly becomes onshore again as the winds respond to lowering
pres to the west. A closed h5 low is progged to be tracking thru the
upr Great Lakes at that point, reaching QC on Thu. This will produce
additional chances for pcpn thru the period. The boundary is progged
to clear the area by late in the week drying things out.
For the latest on Lee, please refer to the NHC.
&&
.AVIATION /13Z SATURDAY THROUGH WEDNESDAY/...
-- Changed Discussion --
High pressure remains offshore as a stationary front remains in
the vicinity of the terminals through the weekend.
Starting at MVFR to IFR with conditions improving to VFR by noon
for most terminals. TSTMs possible in the afternoon to early
evening.
Winds remain light to start, but directions will vary depending
on the terminals location relative to the stationary front. A
S-SE flow increases thereafter, but wind speeds should largely
be 10 kt or less into the evening.
THE AFTERNOON KJFK, KLGA AND KEWR HAZE POTENTIAL FORECAST IS
YELLOW...WHICH IMPLIES SLANT RANGE VISIBILITY 4-6SM OUTSIDE OF
CLOUD.
NY Metro (KEWR/KLGA/KJFK/KTEB) TAF Uncertainty...
Timing of VFR onset this morning may be off by 1-2 hours.
Amendments likely for thunderstorm timing this afternoon and
evening.
OUTLOOK FOR 12Z SUNDAY THROUGH WEDNESDAY...
Sunday-Monday: Showers with a few thunderstorms possible mainly
each afternoon and evening. MVFR or lower conditions possible
in stratus and fog , especially at night and early morning.
Tuesday: Mainly VFR. Chance of showers.
Wednesday: Showers likely with MVFR to IFR possible.
Detailed information, including hourly TAF wind component forecasts,
can be found at: https:/www.weather.gov/zny/n90-- End Changed Discussion --
&&
.MARINE...
With a weak pressure gradient in place, winds and seas will remain
below SCA thresholds through early next week.
Swells from distant Hurricane Lee build midweek, with SCA seas
likely developing on the ocean by Wednesday. Ocean seas may
reach 10 to 15 ft by late Friday.
&&
.HYDROLOGY...
A stationary frontal boundary and humid air mass in place will
allow for scattered convection that could produce heavy
downpours this aft/eve and again Sunday, particularly for NYC,
NE NJ, and the lower Hudson Valley. With multiple rounds of
slow moving showers and thunderstorms expected, there is
potential for isolated to scattered areas of flash flooding
either day.
Slow moving shwrs and tstms could produce areas of mainly minor
flooding Mon. No widespread hydrologic impacts are expected
Tue- Fri.
&&
.TIDES/COASTAL FLOODING...
A low risk of rip currents is forecast at the Atlantic Ocean
beaches this weekend with light winds under 10 kts and 2 to 3
ft waves.
High surf as well as dangerous rips are possible along the
oceanfront next week.
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
CT...None.
NY...None.
NJ...None.
MARINE...None.
&&
$$
SYNOPSIS...JMC/DR
NEAR TERM...DR
SHORT TERM...DR
LONG TERM...JMC
AVIATION...JC
MARINE...JMC/DR
HYDROLOGY...JMC/DR
TIDES/COASTAL FLOODING...