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682
FXUS61 KOKX 191951
AFDOKX

Area Forecast Discussion
National Weather Service New York NY
351 PM EDT Wed Jun 19 2024

.SYNOPSIS...
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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.
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&&

.NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
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Core of the anomalous middle and upper level anticyclone/ridge
remains overhead tonight. Strong subsidence will continue
to keep any convection well to our north this evening.

While it is how across the area, temperatures are several
degrees below any records for June 19. Some locations in the
Heat Advisory may fall just short of observing a 95 or higher
heat index before temperatures start to cool this evening. Dew
points should also start to drop into the evening as some drier
air mixes down, especially away from the immediate coast, due to
the subsidence aloft and nearby surface ridging.

Mostly clear skies are forecast tonight with just some high
cirrus clouds possible at times. Temperatures will fall into
the upper 60s for most locations with low 70s likely in urban NE
NJ and the NYC metro.
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&&

.SHORT TERM /6 AM THURSDAY MORNING THROUGH FRIDAY NIGHT/...
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The Heat Advisory has been extended into Friday evening for NE
NJ and remains in effect for much of the Lower Hudson Valley and
interior S CT through Thursday evening.

The anomalous ridging will slowly shift to our south and west
Thursday with more steadily decreasing heights aloft on Friday.
A cold front will slowly move towards the area and start moving
from north to south across the area late Friday into Friday
night.

There has not been too much change with the overall thinking for
Thursday with the likelihood of temperatures warming a couple
of degrees compared to Wednesday. 850mb temps rise slightly to
18-20C for Thursday. Dewpoints could have a difficult time
mixing out across the interior, being closer to moisture
convergence and where 850mb temps will be higher than the rest
of the area. Otherwise, most of the area except for the coast
should see dew points mix out a few degrees in the afternoon as
has been the case the last few days. The ongoing advisory looks
reasonable for Thursday and do not see a need to include any
other zones not in it since conditions have fallen short the
last few days.

The cold front starts to approach from the north late Thursday,
but think any convection will stay north during the day. An
isolated shower or storm could graze the interior zones Thursday
evening and Thursday night, but otherwise dry and muggy
conditions will continue.

Conditions should heat up quickly Friday morning and early
afternoon. Convection may begin developing just north of the
area late morning/early afternoon and then begin moving into the
interior in the afternoon. This increased cloud cover should
bring highs down a few degrees across the interior and it is
possible that they fail to reach 90 degrees. There will be more
time for heating across NE NJ and the NYC metro. Confidence is
highest across for NE NJ to once again reach advisory criteria .
Higher dew points are likely across the NYC metro which could
yield heat indices around 95, but the 2 day criteria is not
expected to be met. Therefore, no advisory has been issued for
the NYC metro. For coastal areas of CT and Long Island, Friday
will likely be the warmest day of the week with highs in the
middle and upper 80s. A few isolated spots could touch 90 across
NW Long Island and could see a heat index around 95.

The slow moving front will support the convection Friday
afternoon and evening, first across the interior and then slowly
sagging southward towards the coast. Much of the day should be
dry for the southern half of the area, but the approaching front
and subtle shortwaves around the periphery of the ridge support
potential for convection to continue past sunset down to the
coast. Shear is not strong, but a few pulse severe thunderstorms
cannot be ruled out, especially inland. Precipitable waters
around 2 inches, high freezing levels, and a weak steering flow,
could allow storms to train in some areas. WPC has the Lower
Hudson Valley and S CT in a marginal risk for excessive rainfall
with localized flash flooding a possibility. The risk could
reach the coast if convection is able to sustain itself.

Otherwise, the cold front will begin pushing across the area
Friday night with some slightly cooler and drier air beginning
to advect into Connecticut and eastern Long Island. Lows will be
in the 60s for most with lower 70s across NE NJ and NYC metro.
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&&

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

* Quite Humid through the weekend with the chance of showers and t-
  storms both days.

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

A cold front gradually slips south and through at least a portion of
the CWA, before stalling on Saturday. With the humid air mass still
in place and the boundary lingering look for a solid chance of
showers and t-storms across much of the area as the afternoon
progresses as a function of diurnally and air mass driven
instability. PWATs will be on the order of +1.75 inches, thus any
storms that fire up will contain locally heavy rain and perhaps some
gusty winds. The relatively higher chance of storms will be further
north across the area. Late Saturday night into Sunday morning the
boundary is expected to lift back north as a warm front. The front
should get well north of the area towards midday on Sunday. A lead
shortwave out ahead of the main trough / mid level shortwave is
progged by most guidance to arrive during Sunday evening. This may
prime the atmosphere just enough to lead to another round of showers
and t-storms late Sunday into Sunday night. Afterwards forcing
should increase into early Monday as the main cold front begins to
bear down on the region from the west. At this point showers and t-
storms should begin to progress a bit faster as mid and upper level
flow should start to increase. At this point SW to NE training
showers and t-storms are more likely as opposed to stalled or
slower moving activity. Refer to the Hydro section of this AFD for
details regarding potential hydrologic impacts.  ML Excessive
Rainfall progs are suggestive of a marginal to slight risk of flash
flooding for Sunday and a portion of Monday.

At this time Sunday appears to be the hottest and most humid day of
the period. Saturday will be rather warm and humid with heat indices
struggling to reach 95, even across portions of NE NJ. There may be
enough cloud cover at times on Saturday to prevent heat advisory
criteria from being met.  Sunday with thickness ridging working into
the area as the area gets purely into the warm sector and more of a
westerly component to the S to SW flow, look for a larger portion of
the area to reach 95 to 100 heat indices. Perhaps more eastern
location and closer to the ocean fall short of advisory criteria on
Sunday, but it will be muggy nonetheless.  Night time temperatures
will remain rather warm with humid conditions through the weekend.

On Monday the front begins to push through, but with differences in
the timing with global deterministic NWP. Look for Monday to be
unsettled, especially further east across the area with the PWAT
axis later in the day draped across eastern portions of the area.
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 starting to inch up into 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. Late day or evening convection is a possibility late Wed,
but much, if not all of the day will be rain free.
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&&

.AVIATION /20Z WEDNESDAY THROUGH MONDAY/...
High pressure remains over the western Atlantic through the TAF
period.

VFR conditions with winds remaining from the south to southwest,
with the highest winds during the day.


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

Occasional gusts 20 to 23 kt possible this afternoon.


OUTLOOK FOR 18Z THURSDAY THROUGH MONDAY...

Thursday afternoon: VFR. S-SW wind with occasional gusts 15-20
kt.

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

Sunday and Monday: Generally VFR with times of MVFR with a
chance of showers and thunderstorms. 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...
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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 stalled front remains nearby with more showers and t-storms
popping up Saturday afternoon and evening. Another series of showers
and storms will also be likely Sunday afternoon and evening, and
possibly into a portion of Monday as the main cold front moves
through. At any point from late Friday through the weekend, and
possibly into Monday 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. ML Excessive Rainfall progs are suggestive of a
marginal to slight risk of flash flooding for Sunday and into a
portion of Monday. The uncertainty still remains high around
potential hydrologic impacts for this time period.
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&&

.TIDES/COASTAL FLOODING...
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There will be a moderate rip current risk for all ocean beaches
on Thursday and Friday.
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&&

.CLIMATE...
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Here are current record high temperatures for Thursday 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)
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&&

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

$$

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