232
FXUS61 KOKX 170254
AFDOKX

Area Forecast Discussion
National Weather Service New York NY
1054 PM EDT Sun Jun 16 2024

.SYNOPSIS...
High pressure remains centered off the mid Atlantic coast
through Thursday, and weakens Friday through Saturday.
Meanwhile, weak disturbances pass near or just to the north of
the area Friday and Saturday. A stronger wave of low pressure
approaches Sunday.

&&

.NEAR TERM /UNTIL 8 AM MONDAY MORNING/...
Adjusted cloud coverage up for the next few hours to account
for widespread cirrus with a decreasing trend overnight. Despite
this, still had enough radiational cooling to make for
relatively lower temperatures for min temperatures than
previously forecast. Lowered min temperatures a few degrees
overall across the region. Lows forecast range from lower 50s
within parts of the Pine Barrens of Long Island and some
interior areas to lower 60s across NYC and urban NE NJ.

High pressure centered just off the southern New England coast
will slowly drift east tonight. Low level moisture gradually
increases tonight with a SE-S flow advecting higher dew points
into the area. Not so sure there`s going to be low stratus
development to the extent that some guidance, particularly NAM,
is showing overnight with this being the first night of
southerly flow with an antecedent dry airmass. Will include more
clouds cover for parts of the interior, but not to the extent of
NAM. Could be some patchy fog too, but will leave it out for
now.

&&

.SHORT TERM /8 AM MONDAY MORNING THROUGH WEDNESDAY/...
Deep-layered ridging for Monday keeps us rain-free, but it will feel
more muggy than the past couple of days. It`ll be warmer as well as
temps through the boundary layer rise. Expecting highs in the low
80s for a good portion of LI and CT, with middle and upper 80s
elsewhere.

A strong ridge will then be in place Tuesday through Wednesday with
a 500mb high centered near or over us and the surface high offshore
to our east. This should be enough to keep any shower activity out
of the area during this period.

Noted trends in the global models from past 48 hours are that
forecast 850mb temperatures/dewpoints for both Tuesday and Wednesday
have been lowering. This brings some uncertainty regarding how much
surface dewpoints will mix out with daytime heating and resulting
heat indices. Granted not everywhere will be mixing up to 850mb,
particularly for coastal areas where a more southerly flow arrives
off upper 60s water temperatures. But even for the inland areas that
remain with a SW flow, thinking that mixing to this level can occur.
Additionally, without a cold front or significant trough nearby and
thus a lack of moisture convergence, surface dewpoints can mix out a
few degrees from the morning dewpoints on a SW flow both days. Would
be more confident in the higher NBM surface dewpoints (which have
been trending lower as well) if 850mb dewpoints were progged more in
the order of 16-18C instead of the currently progged 10-14C. Have
therefore blended the NBM with some of the lower global guidance MOS
numbers.

Regarding ambient temperatures, 850mb temps are progged at 17-19C
for both Tuesday and Wednesday. With the flow off the cool waters,
expecting highs mostly 85-90 for LI and coastal CT and around 90 for
NYC both days. Otherwise, for inland areas, highs mostly in the mid
90s. It appears that the NBM percentiles may be skewed too warm due
to bias correction methods, so the deterministic NBM, which has been
generally closer to lower end of the distribution for the past
several weeks, was followed more closely, and is more in line with
the anticipated temperatures aloft and low level winds.

After collaboration with the surrounding offices, have decided to go
with heat advisories where there was high enough confidence in
reaching criteria for the two days. This includes all of our NJ
zones and most of our NY zones. Heat indices here expected mostly in
the 95-100 range.

&&

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

* A long duration heat wave is expected through Saturday, possibly
  into Sunday.

* The combination of the heat and humidity will produce heat index
  values of 95 to potentially around 103 during this time.

* Not much relief at night as overnight lows will be in the upper
  60s to the mid 70s, with dew points remaining in the 60s.

A deep layered, and strong upper ridge along the east coast begins
to weaken and flatten across the northeast Wednesday night into
Thursday night as surface high pressure remains anchored off
the mid Atlantic coast. The flow will be more zonal across the
northeast Thursday into the upcoming weekend allowing weak
disturbances in the mid and upper levels to track near or just
north of the region Friday and Saturday. A stronger wave
approaches for Sunday. While the heat and humidity are expected
to continue possibly into the upcoming weekend, the peak is
likely Thursday into Friday. With the anomalous strength of the
ridge there is a chance that temperatures across the interior
may even peak near 100 degrees Thursday and Friday. . Also,
there will not be much relief at night as overnight lows drop
into the mid 60s and lower to mid 70s, especially Thursday night
and Friday night. Also, humidity levels will remain elevated
with dew points mostly in the lower to mid 60s. No record high
temperatures are expected to be set during this time, however
with overnight temperatures remaining elevated a few locations
may set record high minimum temperatures Thursday, and possibly
Saturday. The peak of the heat wave and high heat indices will
be occurring as the transition from spring to summer occurs,
with the solstice Thursday, June 20th at 446 PM EDT. There is a
chance that temperatures do not reach the forecast highs Friday
with the possibility of increased cloud cover, and the chance of
thunderstorms, especially across the northern tier. And desi is
now showing a 90% chance of heat indices reaching 95 or higher
only across portions of northeastern New Jersey. And then with
additional thunderstorms Saturday desi is showing that
northeastern New Jersey will be more marginal for reaching
advisory criteria. So for now advisory headlines may be extended
into Thursday for just about all of the forecast area, and then
possibly for a portion of the area Friday and Saturday.

With the intense heat and high humidity it is important to take
precautions to protect one`s health, particularly those without
effective cooling and/or adequate hydration.

&&

.AVIATION /03Z MONDAY THROUGH FRIDAY/...
Offshore high pressure remains through the TAF period.

Mainly VFR conditions are expected but there is a chance for
some IFR stratus late tonight into early Monday, mainly between
06Z and 12Z. This is indicated by a TEMPO group in the TAF.
Confidence is low to moderate on the stratus occurrence.

Winds will become more southerly tonight and remain southerly
through the rest of the TAF period. Wind speeds tonight will be
near 5-10 kt and then increase Monday to 10-15 kt range with
some slightly higher wind speeds for NYC terminals. Wind gusts
Monday afternoon into early Monday evening are expected to be
near 20-25 kt.

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

Timing of stratus could be a few hours off from TAF. Timing of
gusts on Monday could be a few hours off from TAF as well.

OUTLOOK FOR 00Z TUESDAY THROUGH THURSDAY...

Monday night through Friday: Mainly VFR. Wind gusts subside
early Monday evening. S-SW wind gusts 15-20 kt afternoon into
early evening for Tuesday and Wednesday.

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

&&

.MARINE...
With high pressure remaining in control, sub SCA conditions are
expected on all waters through the end of the week.

&&

.HYDROLOGY...
There are no hydrologic concerns through the end of next week.

&&

.TIDES/COASTAL FLOODING...
A moderate risk of rip currents at the ocean beaches continues
through Tuesday with a southerly flow, and southeast to south swells.

&&

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

&&

$$

SYNOPSIS...JC/MET
NEAR TERM...JC/JM/MET
SHORT TERM...JC
LONG TERM...MET
AVIATION...JM
MARINE...JC/MET
HYDROLOGY...JC/MET
TIDES/COASTAL FLOODING...