000
FXUS61 KOKX 111113
AFDOKX
Area Forecast Discussion
National Weather Service New York NY
713 AM EDT Tue Jul 11 2023
.SYNOPSIS...
Weak high pressure moves east into the area today and builds
more into the area tonight before moving offshore Wednesday. A
frontal system approaches Thursday into Thursday night. A
series of frontal boundaries may approach from the northwest
late in the week through the weekend.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
Adjusted temperatures slightly, particularly in the outlying
rural sections such as near Westhampton, NY. Otherwise, forecast
mainly on track.
High pressure will be weakening to the south and west of the area as
it moves eastward. Ridging aloft will lead to subsidence as the
trough moves well northeast of the local region. Mostly sunny skies
expected overall but there are forecast to be some diurnal cumulus
development for the afternoon especially with the high pressure
being weak.
The airmass gets warmer with westerly flow advecting in warmer air
at 850mb. Models indicate around a 3 degree C increase between 12Z
today and 00Z Wednesday, getting to near 17 degrees C. MOS guidance
several degrees warmer than previous day. Followed NBM for forecast
highs, getting into the upper 80s to lower 90s for much of the
region. Dewpoints mix out during peak heating hours, making for heat
indices right near actual temperatures so heat indices expected to
remain below 95.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH THURSDAY NIGHT/...
For tonight, the weak high pressure area to the south and west
moves into the area and builds in. This will make for subsidence
and a mostly clear night. Surface winds become light. Followed
consensus MOS for lows as they depict a more vast range more
representative of optimal radiational cooling for the forecast
region.
For Wednesday, the weak high pressure area moves east of the
region and becomes based in the Western Atlantic. There is
forecast to be some mid level ridging. Westerly flow at 850mb
will continue to advect in a warmer airmass. Could be enough
instability to introduce next rain in form of showers and
thunderstorms. Atmosphere might be too capped to allow for
shower and thunderstorm development. POPs are only slight chance
in the interior parts of the region with otherwise dry
conditions continuing.
Slight chance for showers remains across the interior for
Wednesday night. Heights in the mid levels will start falling
more. Clouds are expected to be more in coverage not just for
the interior but for the entire region late night going into
Thursday morning.
Thursday into Thursday night, more instability and more forcing
in general. A frontal system approaches the area Thursday night
with a pre-frontal trough likely developing Thursday. Showers
and thunderstorms chances increase during the day across Lower
Hudson Valley, NE New Jersey, NYC, and SW Connecticut. They
spread across the remainder of the area at night. The
thunderstorms will be capable of producing locally heavy
downpours. Some thunderstorms could be possibly strong to severe
Thursday afternoon into early Thursday evening with the highest
instability and potentially up to 35-40 kt of bulk 0-6km AGL
bulk shear.
Temperatures trending warmer for Wednesday and Thursday. Highs
forecast getting more into the 90s. Forecast heat indices getting
around 95 for Northeast NJ Wednesday and for mainly NYC, Northeast
NJ and Western Long Island for Thursday.
&&
.LONG TERM /FRIDAY THROUGH MONDAY/...
Ensemble means depict a closed upper low situated over eastern
Manitoba that slowly works south and east into Ontario though the
period. This results in a mean southwest flow aloft, with multiple
shortwaves passing through the northeast, with generally unsettled
weather, expected into early next week.
For Friday, a frontal system approaches the region from the
northwest along with a mid level shortwave rounding the base of the
upper low. Some uncertainty as to how far south/east the upper low
and shortwave will make it, and whether we`ll have enough upper
level support for organized afternoon convection. Nonetheless, the
air mass in place is moist and marginally unstable and so
thunderstorm chances increase by Friday afternoon across the CWA.
Model BUFKIT soundings are showing some 1500-2000J/kg of MUCAPE,
decent mid level lapse rates, but weak bulk shear of only 20-30kts.
This would suggest some isolated severe thunderstorms are possible
especially north and west of NYC on Friday afternoon. CSU-MLP does
have a wide swath of 5% across much of the area through 12Z
Saturday. In addition, PWATS of 1.4-1.8" raise the potential of
heavy rainfall with any storm. However, steering flow looks to be
near 15-20kts at this point, so any cells should be moving. In
addition, 1- and 3- hr FFG is low (1.5-2.5" in three hours) across
parts of the Lower Hudson Valley where excessive rainfall occurred
this past weekend. Thus, WPC has maintained a marginal risk of
excessive rainfall for the area Friday, with the SLGT risk just to
the north.
The front looks to stall to our east on Saturday into Sunday as
another shortwave in the mid levels rotates through the area. A
surface low pressure then looks to approach from the southwest on
Saturday afternoon into Sunday. Some deterministic model
disagreement here as to whether the low stays south of the area or
heads directly overhead. NBM (and thus its global ensemble inputs)
keeps the bulk of precipitation to the south, so for now have kept
slight chance/chance PoPs in, along with a thunder chance for
Saturday afternoon into Sunday with the moderately unstable airmass
remaining in place.
Shower chances lower by Sunday evening and on Monday, which look to
be a bit drier with the local between systems. The warmest days of
the period look to be Saturday and Sunday, with highs in the upper
80s to near 90. With dewpoints in the low 70s, maximum apparent
temperatures/heat indices will be just a few degrees warmer, but
short of any head headline criteria at this point.
&&
.AVIATION /11Z TUESDAY THROUGH SATURDAY/...
-- Changed Discussion --
VFR. Weak high pressure builds to the south and west into early
morning.
WNW flow increases this morning to 10 kt or less and becomes WSW-SW
into the afternoon. Sea breezes are likely at KJFK, KISP, KBDR, and
KGON. Winds then become light and vrb into the overnight tonight.
...NY Metro (KEWR/KLGA/KJFK/KTEB) TAF Uncertainty...
Timing of sea breeze at KJFK may be off by 1-2 hours. The sea breeze
could make it to KLGA late afternoon/early evening.
An occasional gust 15-18 kt possible at KEWR.
OUTLOOK FOR 00Z WEDNESDAY THROUGH SATURDAY...
Tuesday Night-Wednesday night: VFR.
Thursday: Chance of afternoon showers/thunderstorms with MVFR.
Thursday night and Friday: Showers/thunderstorms likely with MVFR or
lower conditions. IFR possible at times.
Friday night: Chance of evening showers/thunderstorms, then MVFR or
lower conditions possible.
Saturday: MVFR or lower possible in the morning, then chance of
showers/thunderstorms.
Detailed information, including hourly TAF wind component forecasts,
can be found at: https:/www.weather.gov/zny/n90-- End Changed Discussion --
&&
.MARINE...
Below SCA conditions remain on the waters through Thursday
morning. For Long Island Sound as well as Long Island Bays, the
sub-SCA conditions stay through Thursday night. For the ocean,
SCA conditions become more probable Thursday afternoon into
Thursday night.
Marginal SCA conditions remain on the ocean waters Friday into early
Saturday, with waves around 5 and gusts near 25kts. SCA conditions
will gradually diminish early Saturday from west to east across the
ocean zones.
&&
.HYDROLOGY...
No significant widespread rainfall expected into the upcoming
weekend.
&&
.TIDES/COASTAL FLOODING...
There is a moderate risk of rip current development at all the
ocean beaches today and Wednesday. More SW winds with southerly
swells of 2 to 3 ft will be in place across the ocean beaches
during this time period.
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
CT...None.
NY...None.
NJ...None.
MARINE...None.
&&
$$
SYNOPSIS...JM
NEAR TERM...JM
SHORT TERM...JM
LONG TERM...DBR
AVIATION...DBR
MARINE...JM/DBR
HYDROLOGY...JM/DBR
TIDES/COASTAL FLOODING...