868
FXUS61 KOKX 162002
AFDOKX

Area Forecast Discussion
National Weather Service New York NY
402 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/...
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 some 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. Lows will be in the upper
50s for interior and eastern portions of the area with the NYC
metro only falling into the low to middle 60s.

&&

.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 SUNDAY/...
**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 /20Z SUNDAY THROUGH FRIDAY/...
High pressure off the coast will remain in place through
Sunday.

SE-S flow 8-12 kt should diminish this evening and veer more S
overnight. S-SW winds then increase to 5-10 kt Mon morning and
then to around 10 kt with G15-20kt at the metro and coastal
terminals by 16Z Mon.

Still a chance of some low stratus development with IFR
cigs in and around the NYC Metro area overnight. Confidence
remains low to medium and so have continued mention via TEMPO,
generally from about 06Z-10Z but possibly as early as 03Z. Any
low stratus should clear to VFR before the morning push.

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

Low to medium confidence in low stratus development overnight
with IFR cig potential.

OUTLOOK FOR 18Z MONDAY THROUGH THURSDAY...

Monday afternoon and night...Mainly VFR. S-SW winds G20-25kt,
diminishing during the evening.

Tuesday through Friday: VFR.

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
SHORT TERM...JC
LONG TERM...MET
AVIATION...BG
MARINE...JC/MET
HYDROLOGY...JC/MET
TIDES/COASTAL FLOODING...MET