000
FXUS61 KOKX 162223
AFDOKX
Area Forecast Discussion
National Weather Service New York NY
623 PM EDT Wed Aug 16 2023
.SYNOPSIS...
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A stationary front to the south will lift through the area as a
warm front Thursday night. A cold front will move through Friday
afternoon and evening. High pressure will build in for the
weekend, followed by a frontal passage around Tuesday.-- End Changed Discussion --
&&
.NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
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A stationary front remains south of the area as a surface trough
lingers over far western locations. Aloft, a shortwave trough is
passing to our north and becoming sheared out as the flow flattens.
Showers near the sfc trough continue to move through the Lower
Hudson Valley and now into adjacent parts of NYC and SW CT.
Although some instability exists, a mid level cap was noted in
the latest forecast soundings and no thunder is expected. Brief
downpours are possible though. This activity will decrease as
we get into the evening hours, and the overnight should be
mainly dry.
Low temperatures tonight will be right around normal for mid
August, mid 60s to lower 70s.-- End Changed Discussion --
&&
.SHORT TERM /6 AM THURSDAY MORNING THROUGH FRIDAY/...
The aforementioned stationary front just to our south starts to
move north slowly as a warm front Thursday morning. The front
will pass through the area sometime Thursday night, with a
trailing cold front following Friday afternoon into the evening.
Aloft, an amplifying mid and upper level trough will be moving
out of the northern plains and into the Great Lakes and upper
midwest on Thursday. Friday, the trough becomes negatively
tilted and swings overhead.
These features will bring rain and isolated thunderstorms. It
looks like there will be two main rounds, the first with the
warm front moving through, then possibly a lull period before
any activity with the cold front. There are some differences in
guidance with the placement of the warm front and how far east
it gets pushed before jumping north. The NAM has the whole area
solidly in the warm sector with the GFS having the higher
moisture over the eastern half of the area. Right now there is
potential for any showers to produce heavy downpours as PWAT
values could be around 2 inches or higher early Friday morning.
Flooding is not a concern at this time as the activity looks
progressive.
The greatest chance for any severe thunderstorms looks to be
better just to our north. The SPC does have the eastern portion
of the area highlighted in the marginal risk. This is where
instability will be the greatest as the cold front moves
through, with about 1500J/kg of SBCAPE progged.
&&
.LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/...
The cold front will be thru the area by Fri ngt, so with dry air
rushing in aloft, a dry fcst has been maintained. Temps at h85 drop
into the single digits for Sat, but despite this, good mixing on wly
component flow, along with August sun, should allow highs to get to
around 80. Straight mixing without the sun component from the GFS
keeps temps about 5 degrees blw the current fcst. Dry wx still fcst
with the steepest lapse rates and best dpva north of the area.
Continued dry on Sun with rising heights and warming temps. Massive
h5 ridge continues to build over the cntrl CONUS at the same time,
with h5 heights progged to around 600 dam per the GFS. The MEX
guidance has a high of 107 in Omaha on Sunday. This hot airmass
will battle the nrn stream, with an upr low and associated cold
front coming thru the cwa in the Tue-Wed period. The timing is
uncertain attm, with the GFS about a day faster than the 00Z ECMWF.
Due to the uncertainty, the NBM was used for temps Tue-Wed taking
the blended approach, and 20 pops were used for Tue-Wed for tstms
with the front. Most likely day for the temp fcst to be
significantly off is Tue. If the front is indeed slower, highs could
be in the 90s, as opposed to the 70s to around 80 in the grids.
Backing up to Mon, highs were raised a few degrees from the NBM
based on the GFS temps aloft.
&&
.AVIATION /22Z WEDNESDAY THROUGH MONDAY/...
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A stationary front to our south with a weak trough to the north
has led to variable winds across the area and could help promote
some isolated to scattered shower development for some western
terminals. Sea breezes have impacted coastal terminals, with a
general synoptic 5-10 kt SE flow expected to take over later
this evening as a low continues to move closer to us.
Cigs are becoming or already have become MVFR to VFR for many
locations, but should likely drop to IFR, particularly Thursday
morning, for some locations. More fog development near KSWF and
KGON overnight could lead to LIFR conditions. On Thu, a
general 5-10 kt SE flow is expected with sct showers developing
in the afternoon/evening. Cigs should improve to leave things
MVFR to VFR in the afternoon.
...NY Metro (KEWR/KLGA/KJFK/KTEB) TAF Uncertainty...
Shower development this evening was confident enough to include
VCSH in western NYC TAF sites with coverage low. However,
confidence was too low to mention for JFK and LGA as there is
uncertainty as to how far east the showers may develop.
OUTLOOK FOR 18Z THURSDAY THROUGH MONDAY...
Thursday: VFR-MVFR expected during the early afternoon.
Thursday night: Chance of showers and thunderstorms with MVFR
or lower possible.
Friday: Chance of mainly AM showers and thunderstorms with MVFR or
lower possible. W winds G20kt in the afternoon.
Saturday-Monday: VFR.
Detailed information, including hourly TAF wind component forecasts,
can be found at: https:/www.weather.gov/zny/n90-- End Changed Discussion --
&&
.MARINE...
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Winds and seas should remain below advisory levels through
Thursday. An increasing S-SW flow Thursday night will build
ocean seas to near 5 feet by late Thursday night, and to 5-6 ft
Friday.
Marginal SCA conditions Sat mrng should improve thru the day.
Winds and seas blw sca lvls on Sun and Mon, then winds and seas
increase on Tue with a frontal sys potentially impacting the
waters.-- End Changed Discussion --
&&
.HYDROLOGY...
There are no hydrologic concerns through the middle of next
week.
&&
.TIDES/COASTAL FLOODING...
-- Changed Discussion --
On Thursday the rip current risk should be low for the NYC and
Nassau County ocean beaches, and moderate for Suffolk. With
ocean seas building to 5-6 ft, a high risk is possible at all
the ocean beaches for Friday.-- End Changed Discussion --
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
CT...None.
NY...None.
NJ...None.
MARINE...None.
&&
$$
SYNOPSIS...JMC/JT
NEAR TERM...JT
SHORT TERM...JT
LONG TERM...JMC
AVIATION...BR
MARINE...JMC/JT
HYDROLOGY...JMC/JT
TIDES/COASTAL FLOODING...BG