946
FXUS61 KOKX 201002
AFDOKX

Area Forecast Discussion
National Weather Service New York NY
602 AM EDT Thu Jun 20 2024

.SYNOPSIS...
High pressure over the western Atlantic remains in control
through late this week. A cold front slides down from the
north Friday into Friday night and stalls close by on Saturday.
The front lifts north as a warm front Sunday with a cold front
to follow on Monday. High pressure settles in Tuesday and
Wednesday.

&&

.NEAR TERM /THROUGH TONIGHT/...
The forecast is mostly on track early this morning.

High pressure weakens a little over the region today. Most of the
forecast area will be dry, but a pre-frontal trough with moisture
convergence may help spark some showers/TSTMs across the northern
zones. Any storms could produce a strong wind gust or small hail,
but with weak shear, the threat of severe thresholds being met will
be limited to just off to our north, but not completely out of the
question over here.

The trough will also make it tough for dewpoints to mix out in its
vicinity, so dewpoints across the northern zones will probably hover
around 70 for a good portion of the day. Farther south, a somewhat
drier boundary layer and lower surface dewpoints for the most part.
850mb temps at 18-20C, so ambient temperatures should be a little
higher than yesterday`s. Heat advisories for this period remain
unchanged.

&&

.SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
A cold front approaches on Friday, stalls over or near the forecast
area late in the day into Friday night, then begins to retreat north
as a warm front on Saturday. SBCAPES across the northern zones may
increase to 1000-2000 J/kg. With lift from approaching front and
subtle shortwaves aloft, showers and sct TSTMs will be likely across
these zones in the afternoon and evening. PoPs capped at chance for
now across the rest of the forecast area. While a little stronger
than today, shear remains weak, but can`t rule out a strong to
severe wind gust north of the city.

Temperatures and dewpoints for Friday continue to present some
challenges. It appears that the cold front and potential
convection/associated clouds have been delayed by a few hours from
what was progged 24 hours ago. This will give the northern zones a
little more time to heat up, but there`s discrepancy among the
models regarding how hot it can get here beforehand. 850mb temps
vary from as little as 16-17C to as high as 19-20C, with the higher
values generally towards the west. Farther south, a little more
confidence in the high temperature forecast. With the approaching
front, dewpoints in the lower 70s across the northern zones and
upper 60s for most the southern zones.

Regarding heat indices and advisories, there was enough confidence to
extend the advisory for the Lower Hudson Valley as well as Northern
Fairfield and Northern New Haven Counties. Farther east in CT,
temperatures probably not warm enough to support another day of
widespread 95+ heat indices. And while indices of at least 95 might
be widespread in NYC, parts of the north shore of LI, as well as
Southern Westchester and Southern Fairfield Counties, it`s not
anticipated to be the case today, thus falling short of the 2-day
criteria.

With the stalled front, showers and thunderstorms will remain
possible Friday night and Saturday, with generally higher chances
across the northern zones. PWATs climb to around 2 inches in the
vicinity of the front Friday through Saturday, and with a relatively
weak steering flow, slow moving storms, potentially training along
the cold front, introduce a chance of flash flooding. See the
hydrology section below for more details.

High temperatures on Saturday should be cooler than Friday`s, but
this may continue to trend warmer with a more northerly stalling of
the cold front. Heat advisories may need to be extended into
Saturday, particularly across NE NJ.

&&

.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
**Key Points**

* Hot and Humid on Sunday with showers and t-storms expected late
  Sunday into Sunday night.

* A cold front with showers and t-storms slides through Monday which
  breaks the high humidity and heat.

A warm front will lift north of the region early Sunday.  A lead
shortwave out ahead of the main trough / mid level shortwave is
progged by most guidance to arrive during Sunday evening. This will
lead to another round of showers and t-storms late Sunday into
Sunday night.

Sunday appears to be the hottest and most humid day of
the period with thickness ridging working in. The CWA gets purely
into the warm sector and more of a SW flow. Heat index values will
climb into the 90s for a good chunk of the area, with some 100
values in portions of NE NJ and the Lower Hudson Valley. Heat index
values likely remain in the 80s across eastern Long Island
eastern/coastal CT.

A cold front moves across the area on Monday. Monday will remain
unsettled, with showers likely along with the chances for
thunderstorms. The front should clear the area Monday evening, and
with that the humidity gradually falls into Tue AM. Look for a drier
W to NW flow to begin Tuesday as high pressure works in from the
west. It will only be a subtle air mass change with the humidity
dropping some. The winds will likely shift more to the south late in
the day with humidity levels rising again Tuesday night and
Wednesday. Uncertainty remains with the eastward progression of
upper level energy and the southern extent of a frontal boundary by
late Wednesday into Thursday. Late day or evening convection is a
possibility late Wed, but much, if not all of the day will be rain
free. Rain chances continue into Thursday.

&&

.AVIATION /10Z THURSDAY THROUGH MONDAY/...
High pressure remains over the Western Atlantic through the TAF
period.

VFR conditions expected. Winds will be S-SW through the TAF period.
Some gusts to 15-20 kt will be possible this afternoon into early
evening but may only be occasional. Otherwise, sustained winds will
be mainly near 5-10 kt during the TAF period.

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

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

Occasional wind gusts to 15-20kt possible this afternoon.

OUTLOOK FOR 06Z FRIDAY THROUGH MONDAY...

Thursday night: Mainly VFR. Possible patchy fog with MVFR
visibility reduction near KGON late into early Friday morning.

Friday and Saturday: Mainly VFR. There is a chance for MVFR
or lower conditions in showers and thunderstorms, mainly during
the afternoon/evening hours.

Sunday and Monday: Mainly VFR. There is a chance for MVFR or
lower conditions in showers and thunderstorms, again mainly
during afternoon/evening hours. For Sunday afternoon into early
Sunday evening, S-SW wind gusts 15-20 kt.

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

&&

.MARINE...
Strengthening S flow due sea breeze circulations could push wind
gusts occasionally to around 25kt nearshore across the NY
Harbor and the westernmost ocean waters this afternoon and
evening. Otherwise, conditions will remain below SCA levels
through at least Saturday.

Small craft seas becoming increasingly likely Sunday and Sunday
night along with marginal small craft gusts. Small craft conditions
will likely linger into Monday for a good portion of the ocean
waters, with sub small craft conditions likely continuing for the
non-ocean waters.

Conditions fall below SCA levels on Tuesday, however can not rule
out some lingering SCA seas Tuesday morning on the far eastern
ocean.

&&

.HYDROLOGY...
Showers and thunderstorms Friday afternoon through Saturday are
expected to produce an average of a half inch to an inch of rainfall
north of NYC, and lower amounts for NYC, LI and NE NJ. There is a
threat of higher amounts as the storms may redevelop along a stalled
cold front and move slowly. There is therefore at least a low risk
for localized flash flooding during this period, mainly north of the
city, where the front will be stalled.

Another round of moderate to locally heavy rainfall will be possible
Sunday and into a portion of Monday. The uncertainty remains high
around potential hydrologic impacts for this time period.

&&

.TIDES/COASTAL FLOODING...
There will be a moderate rip current risk for all ocean beaches
today through Friday with a S to SW wind wave.

&&

.CLIMATE...
Here are current record high temperatures for today and Friday.

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 Friday for CTZ005-006.
     Heat Advisory until 8 PM EDT this evening for CTZ007-008.
NY...Heat Advisory until 8 PM EDT Friday for NYZ067>070.
NJ...Heat Advisory until 8 PM EDT Friday for NJZ002-004-006-103>108.
MARINE...None.

&&

$$

SYNOPSIS...BC/JC
NEAR TERM...JC
SHORT TERM...JC
LONG TERM...BC
AVIATION...BC
MARINE...BC/JC
HYDROLOGY...BC/JC
TIDES/COASTAL FLOODING...
CLIMATE...