249
FXUS61 KOKX 311727
AFDOKX
Area Forecast Discussion
National Weather Service New York NY
127 PM EDT Wed Jul 31 2024
.SYNOPSIS...
A weak surface trough will linger over the area through the end
of the week. A series of weak fronts will follow this weekend
into early next week.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
A weak surface trough will linger over the region into tonight.
Heat Advisory has been issued for much of NE NJ, NYC metro, and
Nassau County through Thursday evening. Combination of
temperatures around 90 and dew points in the lower to middle 70s
should yield a heat index around 95 this afternoon, likely
occurring again on Thursday.
Ongoing convection across eastern LI will likely weaken as it
continues moving NE towards New England early this afternoon.
Starting to see scattered showers developing N and W of NYC
metro, and coverage should increase the rest of the afternoon.
Some thunderstorms are possible, but overall forcing and shear
are weak limiting organization. A few locally heavy downpours
are possible given PWATs around 2 inches.
Highs should reach the middle and upper 80s for most with around
90 in the Advisory area. Heat indices generally in low 90s with
around 95 in the Advisory. Cloud cover/convection could prevent
readings from touching criteria this afternoon.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH FRIDAY NIGHT/...
Backside of trough tonight, with negative vorticity advection,
drying out, clouds decrease. More ridging expected Thursday with
more nearly steady height tendency thereafter through Friday
before next shortwave trough approaches Friday night. This will
bring potentially more coverage of showers and thunderstorms.
For Thursday and Friday, more sun expected in the morning with
the possibility of afternoon into early evening showers and
thunderstorms. Thursday max temperatures forecast are in the
low to mid 90s. For Friday, max temperatures more in the upper
80s to lower 90s, which are a few degrees cooler than previous
forecast but dewpoints are forecast to be slightly higher than
those of Thursday. Friday, showers and thunderstorms remain
probable for a longer time through Friday night.
850mb temperatures trend a few degrees warmer, closer to 19
degrees C, compared to 850mb temperatures forecast for
Wednesday. Expecting more widespread 95 to 100 degree heat
indices both days. However with a relatively higher chance of
showers and thunderstorms Friday, more uncertainty on Friday`s
temperatures.
Considering Wednesday`s mid 90s heat indices forecast, there is
satisfaction of criteria for heat advisory for much of NE NJ,
NYC and Nassau NY as heat indices forecast for Thursday for
these locations will be around 100. Heat advisories may very
well need to be extended into Friday with later forecasts but
forecasts for Friday high temperature did trend a few degrees
lower compared to previous forecast. So confidence at this time
not high enough to extend heat advisory into Friday.
&&
.LONG TERM /SATURDAY THROUGH TUESDAY/...
Key Points:
* Multiple rounds of showers and thunderstorms possible each day
into Monday.
An active upper flow will be in place through much of the period,
with the area on the southern fringe of the westerlies and several
upper level disturbances moving through, which should bring diurnal
convection each day through Monday. The best days for convection
look to be Thu and again Sat/Sunday. Coverage may be more limited on
Fri as any lead disturbances ahead of a closed low over the Ohio
Valley will be moving through downstream shortwave ridging.
The closed low is poised to affect the area through the weekend.
Temps for the weekend may not be quite as warm but could be offset
by higher dewpoints to yield 95+ heat index values in spots,
especially NE NJ and in/around NYC.
&&
.AVIATION /18Z WEDNESDAY THROUGH SUNDAY/... -- Changed Discussion --
A bit of a tough
aviation forecast for this afternoon and evening. Showers and
thunderstorm have and are developing along a slow- moving cold
front. Currently there are scattered showers across the area
with some thunderstorms, but city terminals may or may not
experience thunderstorms. For now, there is -SHRA and VCSH in
the TAFs through 01Z, with TEMPOs in place for -TSRA, but
amendments are possible the rest of the afternoon and evening.
Most are VFR, but MVFR will be possible with area precipitation
through 1-2Z early tonight.
VFR takes over for the rest of the TAF period under weak high
pressure.
S to SW winds 8-12 kt expected today. Winds become a bit more
SW-W tonight, with winds falling below 10kt. Tomorrow, winds
will be SW 5-10 kts.
...NY Metro (KEWR/KLGA/KJFK/KTEB) TAF Uncertainty...
Amendments will be possible for timing of any precipitation today as
well as timing any flight category changes.
OUTLOOK FOR 18Z THURSDAY THROUGH MONDAY...
Thursday: VFR.
Friday-Sunday: Chance of MVFR or lower in afternoon/evening
showers/tstms.
Monday: VFR.
Detailed information, including hourly TAF wind component
forecasts, can be found at: https:/www.weather.gov/zny/n90-- End Changed Discussion --
&&
.MARINE...
An SCA is in effect for the ocean waters with building seas to
around 5 ft and marginal gusts to 25 kt into this evening.
Elevated seas continue into tonight. Otherwise, winds and seas
will remain below SCA levels through Saturday with a relatively
weak pressure gradient.
Increasing/persistent S-SW flow may allow ocean seas to build
to 5-6 ft late Sat night into Sunday.
&&
.HYDROLOGY...
Multiple rounds of showers and thunderstorms are possible
through this weekend. While widespread flood impacts are not
expected, localized urban and poor drainage flood impacts are
possible.
&&
.TIDES/COASTAL FLOODING...
A high rip current risk continues into this evening with S flow
15 kt and incoming 5 ft/7-sec period swells. Winds diminish and
turn more SW-W on daytime Thu, but still expect at least a
moderate risk, possibly high into Thu morning, due to residual
3-ft swell.
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
CT...None.
NY...Heat Advisory until 8 PM EDT Thursday for NYZ072>075-176>179.
High Risk for Rip Currents until 9 PM EDT this evening for NYZ075-
080-081-178-179.
NJ...Heat Advisory until 8 PM EDT Thursday for NJZ004-006-103>108.
MARINE...Small Craft Advisory until 6 AM EDT Thursday for ANZ350-353.
Small Craft Advisory until midnight EDT tonight for ANZ355.
&&
$$
SYNOPSIS...BG/JM
NEAR TERM...JM/DS
SHORT TERM...JM
LONG TERM...BG/NV
AVIATION...BR
MARINE...BG/JM
HYDROLOGY...BG/JM
TIDES/COASTAL FLOODING...