206
FXUS61 KOKX 181954
AFDOKX

Area Forecast Discussion
National Weather Service New York NY
354 PM EDT Tue Jun 18 2024

.SYNOPSIS...
High pressure over the western Atlantic remains in control
through late this week. A cold front moves in from northwest
on Friday and stalls over the area to begin the weekend. The
front then moves back north as a warm front on Sunday. A more
potent cold front approaches for Monday and moves through Monday
night. High pressure returns on Tuesday.

&&

.NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/...
Upper level anticyclone/ridging continues to build aloft
tonight with high pressure over the Western Atlantic. A weak
trigger in the form of differential heating to our northwest has
initiated some isolated convection just NW of Orange County.
The building heights and middle level cap will prevent this
activity from organizing and moving into western Orange. Have
left PoPs out of Western Orange County for now. Otherwise, dry
and warm conditions are expected tonight. Dew points have been
running a degree or two higher this afternoon, but expecting
them to mix out a bit into the lower 60s this evening and
tonight as subsidence and some drier air advects north around
the surface high. Lows will be in the middle to upper 60s for
most spots with some low 70s in the NYC metro.

&&

.SHORT TERM /6 AM WEDNESDAY MORNING THROUGH THURSDAY NIGHT/...
Heat Advisories remain in effect across NE NJ, the Lower
Hudson Valley, and interior CT through Thursday evening.

*Key Messages*

*Heat wave is expected to continue through at least Thursday,
 but model guidance has continues to trend down a bit in recent
 cycles with temperatures and dew points.

*Temperatures across NE NJ, Lower Hudson Valley, and interior
 CT reach the lower and middle 90s with heat indices 95 to 98.
 Most places should remain below 100 for max heat index both
 Wednesday and Thursday.

*Temperatures in the NYC metro should reach 88-93, highest on
 Thursday. Peak heat index values in NYC metro now look to be
 91-94 on Thursday with some isolated areas touching 95. Due to
 limited coverage of reaching 95, have held off on expanding
 the heat advisory into the NYC metro.

*Onshore flow will keep much of Long Island and coastal CT a bit
 cooler both Wednesday and Thursday. Highs should top out in the
 middle to upper 80s with heat indices around 90. Portions of
 NW Long Island may be a bit warmer, but should fall short of 95
 heat index.

The core of the upper anticyclone/ridge will set up right over
the region on Wednesday. A general consensus of the latest
guidance indicates 500 mb heights will peak around 596dm-598dm
Wednesday into Wednesday night, which is close to the observed
max for KOKX per the SPC Sounding Climatology. However, the
highest temperatures and dew points look to remain north of the
area due to the orientation of the flow around the upper
anticyclone. The center of the anticyclone will start to shift
to the south and west on Thursday, but moreso Thursday night
into the end of the week.

The NBM has continued to shrink the spread in the temperature
distribution for both Wednesday and Thursday with the
deterministic nearly the 50th percentile for both days. This
has led to increased confidence that the current heat advisory
looks good with locations across NE NJ, Lower Hudson Valley, and
interior CT reaching the lower to middle 90s and heat indices
in the mid to upper 90s. Onshore flow likely holds temperatures
down just enough over much of the NYC metro and coast to prevent
heat indices from reaching 95 on Wednesday. In fact, highs for
the NYC metro have trended down and could struggle to exceed 90
on Wednesday.

Similar concerns are present on Thursday. While actual air
temperatures may rise another few degrees from Wednesday, they
still have lowered in the NBM with much smaller spread. Dew
points should be a bit higher, but not seeing widespread upper
60s and lower 70s to help push max heat indices into advisory
levels for the metro. Higher temperatures for NE NJ and inland
areas in combo with middle to upper 60s dew points will help
heat indices reach the middle to upper 90s supporting the
ongoing Advisory. It looks like the higher dewpoint/humidity air
will begin pooling to our north along an approaching front from
the north on Thursday, but any convection should remain outside
of the area.

&&

.LONG TERM /FRIDAY THROUGH TUESDAY/...
**Key Points**

* Heat wave will likely be broken up to some degree Friday and
  Saturday, but still quite warm and humid. The chances for showers
  and thunderstorms has increased for the second half of Friday into
  a portion of Saturday.

* Sunday looks to likely be the hottest day with more widespread
  heat and humidity.

* The humidity gets broken late Monday into Tuesday, with a round of
  showers and thunderstorms.

The latest trend of note in the numerical guidance is a trending
further south of a cold front into our area during Friday and into
the early portion of the weekend.  NWP global guidance and some of
the short range guidance like the RGEM point to a cold front sagging
further south now, with QPF and reflectivity output pointing towards
showers and storms for Friday afternoon and evening. With PWATs
rather high, 1.75 to 2 inches any storms to begin the period could
produce locally heavy rainfall as a cold front sags south and likely
stalls to some degree into Friday evening / night. See hydro section
for further details. With the front nearby and the area still not
out of the humid air mass on Saturday look for more showers and
storms to fire up and likely be scattered across the area. Not a
wash out, but in and out of sun and clouds with scattered convection
still being a good bet.

By Saturday night into Sunday morning thickness ridging is indicated
by the consensus of the guidance. This should lead to the warm front
lifting north and putting our areas purely in the warm sector. 5kft
temps are progged by global NWP to get to around 19-20 C. If this
transpires on more of a lower level SW flow Sunday looks to be the
warmest day of the heat spell in terms of widespread 95 heat
indices. Interior portions of the area and possibly the metro could
very well see heat indices between 100 and 105 given the warm front
getting well to the north. Questions remain around the timing of a
lead shortwave / pre-frontal trough ahead of the main mid / upper
level shortwave feature for late Sunday.  Thought it prudent to at
least carry chance PoPs, especially further NW for later Sunday as
things destabilize through the day.  The primary threats for any
storms later Sunday would likely be strong winds and heavy rain. The
main shortwave / trough then pivots through into Monday as a
stronger cold front pushes through with the ongoing chance of
convection. By Monday night into Tuesday things should improve from
west to east, with less humid conditions with clearing skies. It
will still be quite warm on Tuesday with increased mixing and
downsloping on a westerly component to the wind, but the humidity
should be lower.

&&

.AVIATION /19Z TUESDAY THROUGH SUNDAY/...
High pressure remains in place offshore midweek.

VFR through the TAF period.

S-SW flow 10-15 kt into the early evening, and gusts 20-25 kt at
coastal terminals. Winds drop below 10 kt tonight. Speeds just a tad
lighter on Wednesday, near 10 kt, with gusts up to 20 kt possible by
late afternoon.

An isolated shower or thunderstorm remains possible at KSWF late
this afternoon, but confidence is low in occurrence.

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

Start and end timing of gusts could be a couple of hours.

The afternoon KJFK, KLGA, and KEWR haze potential is YELLOW,
which implies slant range visibility 4-6SM outside of a cloud.

OUTLOOK FOR 18Z WEDNESDAY THROUGH SUNDAY...

Wednesday PM and Thursday: VFR. S-SW wind gusts 15-20 kt afternoon
into early evening.

Friday thru Sunday: Potential for MVFR or lower conditions in
showers and thunderstorms, mainly in the afternoon/evening hours.

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

&&

.MARINE...
Strong S flow due to afternoon sea breeze circulations may push wind
gusts around 20 kt nearshore across the NY Harbor and ocean waters
into this evening and then again both Wednesday and Thursday
afternoons. Otherwise, conditions will remain below SCA levels
through the end of the week.

Sub small craft conditions will continue through Friday night with a
S to SW wind. As a cold front moves nearby and perhaps over the
waters the winds will likely be more out of the SE for Saturday with
ocean seas getting closer to 4 ft. Marginal small craft seas for the
ocean waters are then expected Saturday night into Sunday. Marginal
small craft gusts are then possible for the ocean waters during
Sunday afternoon.

&&

.HYDROLOGY...
A cold front will bring scattered showers and t-storms for Friday
and possibly Friday night. Some storms could linger, although likely
won`t be as widespread on Saturday. Any stronger storms will likely
produce locally heavy rainfall with a low risk of localized flash
flooding. This will depend on the speed of the storms which is too
early to assess at this time.  Another round of storms is possible
late Sunday and again into Monday with uncertainty around potential
hydrologic impacts.

&&

.TIDES/COASTAL FLOODING...
There is a moderate rip current risk for the western ocean beaches,
and a low rip current risk for the Suffolk ocean beaches on
Wednesday. There will be a moderate rip current risk for all ocean
beaches on Thursday.

&&

.CLIMATE...
Here are current record high temperatures for Wednesday through
Friday.

Wednesday, June 19

NYC: 98(1994)
LGA: 97(1994)
JFK: 98(1994)
EWR: 102(1994)
ISP: 96(1994)
BDR: 96(1994)

Thursday, June 20

NYC: 98(1923)
LGA: 98(2012)
JFK: 94(2012)
EWR: 98(2012)
ISP: 93(1995)
BDR: 93(1953)

Friday, June 21

NYC: 97(1988)
LGA: 98(2012)
JFK: 97(2012)
EWR: 100(1953)
ISP: 95(2012)
BDR: 96(2012)

&&

.OKX WATCHES/WARNINGS/ADVISORIES...
CT...Heat Advisory until 8 PM EDT Thursday for CTZ005-006.
     Heat Advisory from noon Wednesday to 8 PM EDT Thursday for
     CTZ007-008.
NY...Heat Advisory until 8 PM EDT Thursday for NYZ067>070.
NJ...Heat Advisory until 8 PM EDT Thursday for NJZ002-004-006-
     103>108.
MARINE...None.

&&

$$

SYNOPSIS...JE/DS
NEAR TERM...DS
SHORT TERM...DS
LONG TERM...JE
AVIATION...DR
MARINE...JE/DS
HYDROLOGY...JE/DS
TIDES/COASTAL FLOODING...
CLIMATE...