000
FXUS61 KOKX 041445
AFDOKX
Area Forecast Discussion
National Weather Service New York NY
1045 AM EDT Mon Sep 4 2023
.SYNOPSIS...
High pressure remains in control through midweek then begins to
weaken Thursday as a cold front slowly approaches from the west
through Friday. The front moves into the region Friday night
into Saturday, possibly lingering nearby into Sunday.
&&
.NEAR TERM /THROUGH TONIGHT/...
-- Changed Discussion --
Showers and weak embedded thunderstorms continue to pass over
far western locations and mainly to our west as shortwave
energy rounds an upper ridge. Any rainfall will be light and
brief. The lightning has been farther north across upstate NY
and west, with MUCAPE values around 1000 J/KG. This activity
will be out of the area by noon.
A high amplitude upper level ridge east of the Mississippi
River Valley and a blocking upper low over the western Atlantic
will allow for an unusually warm airmass to settle across the
region for the first half of the week. 85H temps increase to
around 18C today where they will remain or slightly increase
through mid week.
Much of the area today will get up into the upper 80s to around
90, with the lower 90s across the NYC metro area. The highest
temperatures will be across urban NE NJ. These temperatures are
about 10 degrees above normal. A Heat Advisory remains up
across NE NJ with the exception of western Passaic county. A
heat advisory is issued for heat index values of 95 or greater
for any length of time occurring on two consecutive days, or 100
to 104 for any length of time. The former fits this scenario.
Elsewhere, the coverage of heat index values of 95 or higher is
more spotty, mainly across NYC and portions of the Lower Hudson
Valley. There is a chance criteria could be met in subsequent
days. There is also some uncertainty with the dew point forecast
as it`s possible the low-levels dry out a bit more than forecast
due to mixing from daytime heating. This would have the effect
of lowering heat index values.
Later this afternoon/early this evening, MUCAPES in these same
areas get up to between 1000-2000 J/KG. While there is no low-
level forcing to break the cap, there could be some upper level
lift as an additional shortwave drops down from the north. There
is little guidance supporting any activity over land, so for
the time will have a slight chance of showers/thunderstorms just
south of NYC across the adjacent waters. However, would not be
surprised if this needs to be expanded over land in subsequent
forecasts.-- End Changed Discussion --
&&
.SHORT TERM /TUESDAY THROUGH WEDNESDAY/...
Not much change during this period as the upper level ridge
translates a bit father east, but once again being blocked by
an upper low offshore. There looks to be some slight warming of
the vertical temperatures profiles. This combined with
increasing humidity will raise the potential for the heat
advisory being expanded farther north and east.
Airmass will remain capped during this time with no showers and
thunderstorms in the forecast.
Highs will generally be in the upper 80s to lower 90s, possibly
reaching 95 across urban NE NJ on Wed. It will be cooler across
far eastern LI, Atlantic beaches, and coastal SE CT due to a
marine influence. Lows will be mainly in the upper 60s to
around 70, except in the lower to mid 70s across the NYC metro.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
Not much change in the long term and stuck fairly close to the
previous forecast/NBM blend.
A high amplitude and large subtropical ridge over the eastern states
is expected to weaken and translate slowly eastward Wednesday night
and Thursday. Meanwhile, a closed, and nearly cutoff, low over the
northwestern Atlantic remains south of Nova Scotia and drifts east
Thursday into Friday as a northern stream shortwave approaches from
the west. The high amplitude ridge will keep the shortwave to the
west of the region until Saturday as a near Omega blocking pattern
sets up.
A warm and humid airmass will remain along the eastern states
Thursday and Friday, with temperatures Thursday reaching the upper
80s along the coast, and into the lower 90s, and possibly the mid
90s, inland, nearly 10 degrees above normal. Overnight lows will
generally be 5 to near 10 degrees above normal. While the airmass
remains in place Friday ahead of a cold front, and with a thermal
ridge across the area, with 850mb temperatures 18C to 20C, increased
cloud cover and a chance of precipitation will keep temperatures in
the 80s. Currently, heat indices are forecast to reach the mid 90s
across northeastern New Jersey, portions of the lower Hudson Valley,
and into Southwestern Connecticut Thursday. However, if dew points
lower a could of degrees during peak heating maximum heat indices
will fall short of the mid 90s. Friday will feel more humid with
higher dew points, but with cooler temperatures, heat index values
top off in the upper 80s and lower 90s.
Chances for showers and thunderstorms increase Friday into Saturday
as the upper blocking patter slowly weakens allowing the upper ridge
to move into the western Atlantic and the surface frontal system to
track slowly eastward. There is some timing uncertainty as to how
quickly the blocking and upper ridge weaken, allowing the upper
shortwave to track through the region. Some guidance is slower, and
showers and thunderstorms may linger into the beginning of Sunday.
Drier weather returns for Sunday and Monday as high pressure builds
back into the region behind the cold front.
&&
.AVIATION /14Z MONDAY THROUGH FRIDAY/...
-- Changed Discussion --
High pressure will remain offshore through the TAF period.
Showers and some embedded thunder associated with an upper level
shortwave will move south and west of the terminals through 16Z.
They should remain just west of KEWR and therefore took any
mention of VCTS and SHRA out of TAFs.
Another chance of showers and thunder is expected later today,
mainly after 22Z, as another shortwave moves through.
Confidence of coverage of any precip remains fairly low, however
some of the hi-res guidance is indicating showers off the NJ
coast. So will include a VCTS for JFK and EWR. Once again,
expecting more of a route vs terminal impact.
Otherwise, mainly VFR conditions are expected through the TAF
period.
Light and variable winds are expected this morning, especially
due to the showers and thunderstorms that are moving through
just west of the metro terminals. However winds should end up
being more NW to N for NYC terminals until sea breezes affect
them later this morning and afternoon. All terminals except for
KSWF are expected to develop a sea breeze this afternoon into
early evening. KSWF develops a WNW flow Monday. Wind speeds
Monday will generally be near 5-10 kt. Winds become light and
variable once again tonight into Tuesday morning.
NY Metro (KEWR/KLGA/KJFK/KTEB) TAF Uncertainty...
Low confidence of shower/thunder timing late this
afternoon/evening.
Sound breeze potential for KLGA before ocean sea breeze moves
in.
Timing of southerly sea breeze could be 1-3 hours off from
forecast.
KJFK wind speeds could be a few kts higher than forecast
especially this afternoon.
OUTLOOK FOR 12Z TUESDAY THROUGH FRIDAY...
Tuesday-Wednesday night: VFR.
Thursday: Mainly VFR. Low chance for a late afternoon into
evening shower or thunderstorm.
Friday: MVFR possible at times. Chance for showers and
thunderstorms.
Detailed information, including hourly TAF wind component forecasts,
can be found at: https:/www.weather.gov/zny/n90-- End Changed Discussion --
&&
.MARINE...
Ocean seas generally remain around 3 ft through mid week, however,
an ESE swell from offshore low pressure nearing the Canadian
Maritimes could increase seas for time to around 4 ft late
tonight into Tuesday.
High pressure begins to weaken Thursday as a frontal system
approaches from the west. The frontal system moves slowly through
the region Friday into Saturday. Winds and seas are forecast to
remain below SCA levels at this time.
&&
.HYDROLOGY...
No hydrologic impacts are expected through next week.
&&
.TIDES/COASTAL FLOODING...
Long period ESE swells of 3-4ft and 9-11s continue through Tuesday,
with a moderate rip current risk at the ocean beaches. While
these swells begin to diminish on Wednesday, a moderate risk is
likely to continue, especially for the Nassau and Suffolk
beaches.
&&
.CLIMATE...
Some daily record highs could be tied or broken over the next
couple of days. The record highs for these dates are below.
Daily Record High Temperatures...
Sep 4 Sep 5
Central Park...97 (1929)...94 (1985)
LaGuardia......93 (2018)...93 (1985)
JFK............93 (2018)...94 (1961)
Islip..........92 (2018)...90 (1985)
Newark.........95 (2018)...94 (1985)
Bridgeport.....91 (1973)...91 (1961)
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
-- Changed Discussion --
CT...None.
NY...None.
NJ...Heat Advisory until 8 PM EDT Tuesday for NJZ004-006-103>108.
MARINE...None.-- End Changed Discussion --
&&
$$
SYNOPSIS...BC/DW
NEAR TERM...JT/DW
SHORT TERM...DW
LONG TERM...BC
AVIATION...BC/JP
MARINE...BC/DW
HYDROLOGY...BC/DW
TIDES/COASTAL FLOODING...
CLIMATE...