393
FXUS61 KOKX 311929
AFDOKX
Area Forecast Discussion
National Weather Service New York NY
329 PM EDT Wed Jul 31 2024
.SYNOPSIS...
-- Changed Discussion --
A weak surface trough will linger over the area through the end
of the week. A warm front lifts north of the area Friday night
with a slow moving cold front approaching Saturday. The front
likely pushes through late in the weekend. Weak high pressure
attempts to build during Monday. Another frontal system
approaches for the middle of next week.-- End Changed Discussion --
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
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Convection will likely continue to struggle to organize into
the evening. The main trigger is a weak surface trough, but
shear is very weak which will prevent any significant storm
organization. CAMs have been struggling with depicting how the
convection will evolve this evening. Given the weak trigger and
weak shear, think convective activity will continue to remain
scattered. No severe weather is expected, but a few locally
heavy downpours are possible which could lead to minor flooding.
We received a few reports from some heavier downpours early
this afternoon of 1-1.5 inches an hour rainfall rates. These
higher rates will be isolated. A few showers and possibly a
thunderstorm could continue into the evening east of the Hudson,
but overall coverage should diminish with loss of heating.
Otherwise, mostly cloudy conditions will gradually clear from
west to east through the morning. While there may be some
patchy fog in spots, have left out of the forecast for now due
to uncertainty with wind direction towards morning. The weak
surface trough may dissipate just east allowing for a weak west
flow, which could limit fog development.
Lows will be in the upper 60s inland and lower to middle 70s
elsewhere.-- End Changed Discussion --
&&
.SHORT TERM /6 PM THIS EVENING THROUGH FRIDAY/...
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The heat advisory remains in effect for much of NE NJ, NYC
metro, and Nassau County through Thursday 8pm. Some portions of
the Advisory likely will fall short of reaching a heat index of
95 Wednesday afternoon due to cloud cover and slightly lower
temperatures/dew points than previously anticipated. No changes
were made to the Advisory at this time.
Thursday will be a hot day across the Tri-State. A shortwave
trough pushes offshore allowing for slight height rises aloft.
Ridging is transient and not strong aloft, but there is enough
of a WNW-NW push to bring in a warmer airmass with 850 mb
temperatures reaching 18-19C in the afternoon. The westerly flow
should allow dew points to lower in the afternoon. Even the
typically biased high NBM dew points are indicating that many
areas outside of sea breeze influences will fall into the upper
60s and potentially the middle 60s. Air temperatures should be
able to reach the lower and middle 90s across much of the area
with many places seeing heat indices around 95. In the Advisory
area, heat indices look to range from 95 to 99.
Held off on expanding the Advisory in coverage as Thursday
would just be the first day of reaching criteria. There is
increased uncertainty with Fridays conditions, mainly from
developing onshore flow, higher amounts of moisture and
potential cloud cover, as well as potential afternoon
convection. Right now it appears areas reaching 95 for two
consecutive days is not currently expected to be widespread.
Will also hold off on extending the Advisory for much of NE
NJ, NYC metro, and Nassau due to the same potential negating
factors. There has also been a trend in the guidance to lower
highs on Friday. At this time, reaching criteria on Friday is
marginal and confidence not high enough for an extension.
The higher heights on Thursday will likely suppress convective
development. Forecast soundings are fairly capped in the middle
levels. The lingering surface troughing could be a trigger if
capping breaks or is weaker, but have lowered PoPs to just
slight chance from the NYC metro on NW in the afternoon/early
evening. Convective chances are higher Friday afternoon and
evening with an approaching shortwave aloft. A frontal system
associated with the shortwave may also act as a focusing
mechanism. Timing uncertainties support keeping PoPs no higher
than chance for now.-- End Changed Discussion --
&&
.LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/...
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Subtle height falls take place late Friday and into the weekend
with the mid level trough axis progged to swing through late in
the weekend. A semi-zonal flow with the jet stream remaining
north of the region Monday and Tuesday. Upper level height falls
are then likely to take place towards Wednesday of next week.
Key Points:
* Remaining quite warm and humid into the weekend, with heat
headlines less likely by Sunday.
* Multiple rounds of showers with embedded thunderstorms increase
into the weekend.
* There remains uncertainty around how far east the unsettled
weather will progress during the second half of Sunday into Sunday
night, as the front may hang up offshore into early Monday.
* Mainly dry conditions are expected to return sometime during
Monday into Tuesday.
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
shortwave disturbances moving through, which should bring the
highest chance of diurnal convection late Friday for the western
half of the area, with more widespread activity Saturday and Sunday.
During Friday night into Saturday shower and t-storm chances
increase from west to east. At this time coverage looks to be more
limited on Fri night as any lead disturbances ahead of a closed low
over the Ohio Valley will be moving through downstream shortwave
ridging. The closed low to the north with the trailing lower height
field is poised to affect the area through the weekend as
convective activity is likely to increase.
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 on Saturday. Temperatures are
more likely to be a couple of degrees cooler into Sunday with more
clouds on average as a cold front begins to push through.-- End Changed Discussion --
&&
.AVIATION /19Z WEDNESDAY THROUGH MONDAY/...
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Currently, there are scattered showers across the area with some
thunderstorms along a slow-moving boundary, 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 evening. Most are VFR, but
MVFR will be possible with nearby precipitation through 01Z early
tonight.
VFR takes over for the rest of the TAF period under weak high
pressure. However, isolated thunderstorms are possible Thursday
afternoon/evening. Confidence is too low to include in TAFs at
this time.
S to SW winds 8-12 kt early this evening. 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 21Z THURSDAY THROUGH MONDAY...
Thursday: VFR. MVFR or lower in isolated thunderstorms.
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...
-- Changed Discussion --
An SCA remains in effect for the ocean waters with seas around 5
ft into tonight. Otherwise, winds and seas will remain below
SCA levels through Friday with a relatively weak pressure
gradient.
Increasing/persistent S-SW flow may allow seas to build close to
5 ft late Sat into Sunday for portions of the ocean waters. The
higher likelihood of small craft ocean seas will be Sat. night
into Sunday as a cold front draws closer with some marginal
small craft gusts possible at times. Conditions are expected to
fall below small craft criteria during Monday.-- End Changed Discussion --
&&
.HYDROLOGY...
-- Changed Discussion --
Multiple rounds of showers and thunderstorms are possible
through this weekend. The higher likelihood appears to be late
Friday into the first half of the weekend, with activity
lingering into Sunday. While widespread flood impacts are not
expected, localized urban and poor drainage flood impacts are a
possibility with high humidity and PWATs in place. WPC has a
marginal risk of excessive rainfall for much of the area
Saturday into Sunday.-- End Changed Discussion --
&&
.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...JE/DS
NEAR TERM...DS
SHORT TERM...DS
LONG TERM...JE
AVIATION...BR
MARINE...JE/DS
HYDROLOGY...JE/DS
TIDES/COASTAL FLOODING...