discussion on 2023-09-06

000
FXUS61 KOKX 061819
AFDOKX

Area Forecast Discussion
National Weather Service New York NY
219 PM EDT Wed Sep 6 2023

.SYNOPSIS...
High pressure remains in control today and begins to weaken on
Thursday. A slow moving frontal system will impact the area Thursday
night through the weekend. The associated cold front passes through
late Sunday night into Monday. A second frontal system will follow
on its heels Tuesday.

&&

.NEAR TERM /THROUGH TONIGHT/...
Overall the forecast still remains on track. Only updated to
reflect current observations and trends.

An upper level ridge will remain over the area today, resulting
in temperatures around 10 degrees above average with sunny and
dry conditions.

A heat advisory remains in place for much of the CWA today. The
combination of temperatures in the upper 80s and lower to
middle 90s with high dew points will result in heat index values
in the middle and upper 90s. Only eastern Suffolk county has
been left out of the heat advisory where heat index values
will fall just short of the 95 criteria. Can not rule out a few
locations touching 95 in eastern Suffolk county, though. Some
record high temperatures may be broken today at our climate
sites.

Tonight, it will remain mostly clear, warm, and muggy.
Overnight lows for much of the CWA will drop into the 70s.
Record maximum lows are also possible for some climate sites
tonight.

&&

.SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/...
The upper level ridge starts to weaken and slide east Thursday.
Despite this, the hot and humid conditions will remain in place
Thursday afternoon. Heat advisories remain in effect for NYC, The
Lower Hudson Valley and portions of NE NJ and Connecticut.

Record high temperatures are possible on once again for some climate
sites. Also, the warm conditions continue overnight so record
maximum lows will once again be possible Thursday night. You can
reference the climate section of this AFD for a listing of prior
records.

Isolated showers and/or thunderstorms are possible for western
interior portions of our area Thursday night from a weak frontal
system, but confidence is low on if they will occur.

For Friday, the high continues to weaken as an upper level trough
and cold front slowly approach from the west. Temperatures are
forecast to be about 5 to 8 degrees cooler on Friday, however a
stronger onshore flow should allow dew points to rise a few degrees.
As a result, expected humidity levels to remain high. Right now, it
appears most locations wont need heat headlines, however we will
need to keep an eye on parts of NE NJ, where heat index values will
come close to 95.

Otherwise, with the approaching front and trough, POPS slowly
increase through the day Friday. Will keep most of the area at
Chance or lower. The main threat with any storms will be the locally
heavy rainfall. Temperatures on Friday are expected to be in the
80s.

&&

.LONG TERM /SATURDAY THROUGH TUESDAY/...
A slow moving upper trough over the east with multiple pieces
of energy cutoff from the flow will get kicked slowly eastward
over the weekend as a northern branch trough amplifies as it
tracks across central Canada and the Great Lakes. This will also
send a surface cold front eastward. Ahead of it will be a deep-
layered southerly flow advecting high PWAT values into the
area. There is also some retrogression of the western Atlantic
ridge at the start of the period. This will keep the highest
rain chances initially across the western half of the forecast
area (NW of a line from NYC into SW CT) due to ridging across
eastern sections. Rounds of showers and thunderstorms are forecast
through the weekend as warm advection and convective vorts work
south to north ahead of the approaching cold front. It will not
be raining all the time. There will be diurnal component to
this activity as the airmass destabilizes during the daytime
hours with the best chances from late afternoon through the
first half of the night. For eastern areas of LI and CT, it
could be drier the first half of the weekend until the ridge
over the western Atlantic weakens.

As for rainfall, the 00Z GFS and ECMWF are in very good agreement
with their mass fields through early next week, yielding 1-2
inches of rainfall from NYC and points north and west. To the
east, rainfall amounts will decrease due to the aforementioned
ridging. Localized flash flooding is a possibility at this time.

The cold front passes through Monday morning, but looks diffuse and
may just wash out. The airmass behind it looks a bit drier, but this
will be dependent on if the cold front can fully move to our east.
There is a second frontal system on its heels with an amplifying
upper trough digging south and east across the Great Lakes.
Chances for convection will be on the increase ahead of this
system on Tuesday

While it will cool off some during this time due to rain chances and
cloud cover, it will also be quite humid with dew points around 70
and afternoon highs around 80 (near normal). Lows over the
weekend will be in the upper 60s to lower 70s, before dropping a
bit behind the cold front early next week. Lows will be about 5
to 8 degrees above normal.

&&

.AVIATION /18Z WEDNESDAY THROUGH MONDAY/...
-- Changed Discussion --High pressure remains offshore with a weakening trough across
the local region going into this evening.

VFR conditions are expected to continue for most terminals
through the TAF period. Some patchy light fog reducing
visibilities to MVFR is forecast for KSWF and KGON late tonight
into early Thursday morning.

Winds will be less than 10 kts for much of the TAF period. The
wind direction will be more variable, and will be more dependent
on the trough and sea breezes. Tonight into Thursday morning,
wind speeds will be near 5 kts or less with variable direction
with more of a south wind near 5 to 10 kts Thursday afternoon.

Specifically for this afternoon into start of this evening, sea
breezes are expected for CT terminals for KJFK. Beyond those
terminals, sea breeze timing for KLGA and KISP is more
uncertain. The transition will be NE flow for KLGA and N flow
for KISP to more S flow for both terminals by early this
evening. The other terminals will remain more NW wind direction.


     NY Metro (KEWR/KLGA/KJFK/KTEB) TAF Uncertainty...

Timing of sea breeze for afternoon into early evening for KJFK
and KLGA could be 1-2 hours off from TAF.

Low chance of a sea breeze late this afternoon into early this
evening for KEWR and KTEB.

OUTLOOK FOR 18Z THURSDAY THROUGH SUNDAY...

Thursday: Mainly VFR. S/SW winds. Chance of showers and
thunderstorms to the north and west of NYC terminals afternoon
into evening. A slight chance of showers and thunderstorms
for NYC terminals, KHPN and KBDR late afternoon into evening.

Friday through Saturday: MVFR possible at times in rounds of
showers and thunderstorms, mainly afternoon through evening.
Potential for nocturnal coastal stratus will increase through
this period as well.

Sunday through Monday: MVFR possible at times. Possible late
night into early morning coastal stratus. Chance of showers,
slight chance of thunderstorms. Showers likely for most
terminals Sunday afternoon into early Sunday evening.

Detailed information, including hourly TAF wind component forecasts,
can be found at: https:/www.weather.gov/zny/n90-- End Changed Discussion --

&&

.MARINE...
Sub-SCA conditions are expected through Thursday under high
pressure. A slow-moving frontal system approaches Thursday
night into the weekend. Winds and seas are expected to remain
below SCA levels during this time period.

&&

.HYDROLOGY...
No hydrologic impacts are expected through Thursday.

Locally heavy rainfall is possible Friday into the weekend, but
there is still too much uncertainty with the timing and extent
of the activity.

&&

.TIDES/COASTAL FLOODING...
A moderate risk of rip currents continues today as long period ESE
swells of 3 ft to 10-11s look to continue. The swells may diminish
Thursday, but given a stronger southerly flow in the afternoon and
lingering 9 second periods, it`s possible for moderate in some
locations.

&&

.CLIMATE...
Some daily record highs and lows could be tied or broken over the
next couple of days. The record highs for these dates are below.

Daily Record High Temperatures...

  Sep 6      Sep 7

Central Park..97 (1881)..101(1881)
LaGuardia.....96 (2018)..90 (2015)
JFK...........92 (1985)..93 (1983)
Islip.........90 (1985)..92 (1998)
Newark........98 (2018)..95 (2015)
Bridgeport....92 (2018)..91 (1983)

Daily Record High Minimum Temperatures...

              Sep 6      Sep 7      Sep 8

Central Park..78 (1985)..79 (1881)..76(2015)
LaGuardia.....79 (1985)..74 (2012)..76(2015)
JFK...........77 (1985)..76 (1985)..73(1983)
Islip.........79 (1985)..74 (2012)..76(2015)
Newark........77 (1985)..74 (1999)..73(1999)
Bridgeport....75 (1985)..72 (2016)..74(2015)

&&

.OKX WATCHES/WARNINGS/ADVISORIES...
CT...Heat Advisory until 8 PM EDT Thursday for CTZ005>009.
     Heat Advisory until 8 PM EDT this evening for CTZ010>012.
NY...Heat Advisory until 8 PM EDT Thursday for NYZ067>075-176-178.
     Heat Advisory until 8 PM EDT this evening for NYZ078-080-177-
     179.
NJ...Heat Advisory until 8 PM EDT Thursday for NJZ004-006-103>108.
MARINE...None.

&&

$$

SYNOPSIS...BC/DW
NEAR TERM...BC/BR
SHORT TERM...BC
LONG TERM...DW
AVIATION...JM
MARINE...BC/DW
HYDROLOGY...BC/DW
TIDES/COASTAL FLOODING...
CLIMATE...