-- Discussion containing changed information from previous version are highlighted. --
764
FXUS61 KOKX 191315
AFDOKX

Area Forecast Discussion
National Weather Service New York NY
915 AM EDT Wed Jun 19 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 remains over the region Saturday, then lifts
north as a warm front Sunday. A cold front approaches for Monday and
moves through Monday night. High pressure returns on Tuesday.

&&

.NEAR TERM /THROUGH TONIGHT/...
-- Changed Discussion --
The forecast is on track.

The setup looks similar to yesterday with a 500mb low overhead and
high pressure ridging in from the east. Subsidence from this
combination should be able to prevent any shower development
across the interior or weaken anything trying to approach from
the north and west.

Anticipating the overall distribution of heat indices to be
fairly similar to what was observed on Tuesday. Will leave
headlines unchanged, although between what happened yesterday
and what`s expected for today and Thursday, the 2-day criteria
for advisories will probably not be met for some zones. Heat
indices top out in the 95-100 range for portions within the
advised area. High temperatures should be in the upper 80s and
lower 90s, warmest in NE NJ, with 80s on Long Island and coastal
CT.
-- End Changed Discussion --

&&

.SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/...
High pressure weakens over the region on Thursday with the approach
of a cold front. The front may reach some of the northernmost zones
of the forecast area by sundown. Have included a slight chance of a
shower/TSTM for some of these northern zones in the afternoon and
evening. Shear is pretty weak, so any TSTM that manages to make it
here probably remains sub-severe.

850mb temps rise slightly to 18-20C for Thursday, so high
temperatures expected to be a couple of degrees warmer than today.
Dewpoints could have a difficult time mixing out across the northern
zones, being closer to moisture convergence and where 850mb temps
will be higher than the rest of the area. Other spots away from sea
breezes could see surface dewpoints mixing out by a few degrees in
the afternoon. While the coverage of heat indices of 95+ will be
more widespread, no areas currently not under a heat advisory are
forecast to meet the 2-day criteria. There could be spotty instances
of heat indices reaching 95 in NYC and southern Westchester, but
it`s not looking widespread.

The cold front sags farther into the forecast area Thursday night
and is progged to remain over us during the day Friday. Showers and
thunderstorms likely fire up along the front during the day with the
better overall chances of rain across the Lower Hudson Valley and
CT. Once again, shear doesn`t look too impressive, so severe wx
doesn`t look like much of a threat at this time. However, PWATs may
climb to around 2 inches, and with a relatively weak steering flow,
slow moving storms training along the cold front introduce a chance
of flash flooding. See the hydrology section below for more details.

As for temperatures and heat indices, high temps from the
deterministic NBM seem too warm, moreso across northern zones where
850mb temps are progged at around 17-18C and have a better chance of
a mostly cloudy afternoon with rainfall. Warmer temps aloft will be
found across the southern zones, but the threat of afternoon cloud
cover and showers spilling in, as well as a chance of sea breeze
development, make the surface temperature and dewpoint forecasts
tricky. The current forecast has heat indices of 95+ mostly in NE NJ
and adjacent areas. Given the uncertainty and lack of widespread
criteria met during the Thursday-Friday period, no expansion of
advisories in time and area are being made at this time.

&&

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

* The warm and humid conditions continue into the weekend with the
  warmest day on Sunday. A chance of showers and thunderstorms each
  afternoon.

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

A frontal system will remain over the region Saturday, with mostly
cloudy conditions expected along with chance for showers and
thunderstorms. This should help keep temperatures in the 80s
areawide. It will however remain rather humid with dew points in the
upper 60s to near 70.

By Saturday night into Sunday morning the warm front lifts north and
puts our areas purely in the warm sector. Expect Sunday to be the
warmest day of the weekend with temperatures in the 80s and lower
90s. Dew points in the 70s will make heat index values reach 80s and
90s, with a few spots in NJ coming close to 100.  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 /13Z WEDNESDAY THROUGH SUNDAY/...
High pressure over the western Atlantic through the TAF period.

VFR conditions with winds remaining from the south to southwest.

Winds will remain below 10kts this morning. Winds increase this
afternoon to near 10-12 kt with gusts up to 20 kt mainly for the NYC
and coastal terminals. Any gusts that develop will diminish around
or shortly after sunset.

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

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

Timing of gusts could be 1-2 hours off from TAF.

OUTLOOK FOR 12Z THURSDAY THROUGH SUNDAY...

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

Friday thru Sunday: Potential for MVFR or lower conditions in
showers and thunderstorms, mainly in the 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 20-25 kt nearshore across the
NY Harbor and the westernmost ocean waters for both this
afternoon and Thursday afternoon. Otherwise, conditions will
remain below SCA levels through the end of the week.

As a frontal boundary 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. Seas are forecast to reach SCA levels Sunday
through Monday night as winds increase ahead of and with a cold
front.

&&

.HYDROLOGY...
Showers and thunderstorms Friday into Friday night 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.

A chance of showers and thunderstorms will be possible both days
this weekend. 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 Monday
with uncertainty around potential hydrologic impacts.

&&

.TIDES/COASTAL FLOODING...
There is a moderate rip current risk for all ocean beaches today
and Thursday.

&&

.CLIMATE...
Here are current record high temperatures for today 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...
-- Changed Discussion --
CT...Heat Advisory until 8 PM EDT Thursday for CTZ005-006.
     Heat Advisory until 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.
-- End Changed Discussion --

&&

$$

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