553
FXUS61 KOKX 311127
AFDOKX
Area Forecast Discussion
National Weather Service New York NY
727 AM EDT Wed Jul 31 2024
.SYNOPSIS...
A weak cold front approaches from the west today and moves
across and dissipates within the region tonight. A series of
weak fronts will follow from Thursday into Monday.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
The convection forecast today lowered from the previous
forecast in terms of POPs and went with coverage wording for
showers and thunderstorms.
Overall, it appears the highest combination of instability and
vertical forcing is present during the latter half of this
afternoon, particularly across Western Long Island extending back
west through NE NJ including the NYC Metro as well as the Lower
Hudson Valley and SW CT.
Mesoscale models show not too much coverage in terms of
convection for today. Models have also indicated a bit more sun
compared to previous forecast. Leaned towards warmer MAV MOS
for high temperature forecast, thinking there will be more
sunshine and more limited coverage of convection. Coverage of
convection gets more scattered to numerous latter half of this
afternoon.
Have temperatures reaching upper 80s to near 90 along with
dewpoints in lower 70s for this afternoon within much of NE NJ,
NYC, and Nassau NY. Heat indices forecast in the low to mid 90s.
&&
.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 /12Z WEDNESDAY THROUGH SUNDAY/...
-- Changed Discussion --
An upper level low will move into southern Canada. Meanwhile, a
weak cold front approaches the area today.
MVFR or IFR will continue through the morning push, then an
improvement to VFR is expected, mainly between 14-17z. There is
an area of showers across central NJ, which is moving
northward. Expect some scattered showers through about 14z.
Will include a tempo for this rain. VFR conditions are then
expected to return for the afternoon.
Another round of showers and possible thunderstorms are then
expected again after 18z with the approach of a weak cold
front.
S to SW winds 08-12 kt expected today. Some gusts can not be ruled
out at the coastal terminals. Any gusts should reach about 20kt.
Winds become a bit more SW-W tonight, with winds falling below 10kt.
...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, especially this
morning.
Occasional gusts to near 20 kt possible.
OUTLOOK FOR 12Z THURSDAY THROUGH SUNDAY...
Thursday: VFR.
Friday-Sunday: Chance of MVFR or lower in afternoon/evening
showers/tstms.
Detailed information, including hourly TAF wind component
forecasts, can be found at: https:/www.weather.gov/zny/n90-- End Changed Discussion --
&&
.MARINE...
Conditions currently below SCA on all waters. The conditions are
expected to remain below SCA thresholds for non-ocean waters
through Saturday. However, for the ocean waters, guidance
continues to indicate building seas to SCA levels for today into
tonight with more southerly flow ahead of approaching cold front.
Wind gusts will be more marginal but there are some 25 kt gusts
forecast for the ocean this afternoon into evening. For
Thursday through Saturday, ocean waters are forecast to be below
SCA thresholds with an overall 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.
Potential for more widespread heavy rain Friday into Friday
night with trough approaching and PWATs potentially just
exceeding 2 inches.
&&
.TIDES/COASTAL FLOODING...
A high rip current risk should continue into today 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 from 1 PM this afternoon to 8 PM EDT Thursday
for NYZ072>075-176>179.
High Risk for Rip Currents through this evening for NYZ075-080-081-
178-179.
NJ...Heat Advisory from 1 PM this afternoon to 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
SHORT TERM...JM
LONG TERM...BG/NV
AVIATION...BC
MARINE...BG/JM
HYDROLOGY...BG/JM
TIDES/COASTAL FLOODING...