632
FXUS61 KOKX 210342
AFDOKX
Area Forecast Discussion
National Weather Service New York NY
1142 PM EDT Fri Jun 20 2025
.SYNOPSIS...
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Western Atlantic high pressure will get more established through
the weekend. A few disturbances pass through, mainly across
northern portions this weekend. High pressure just southwest of
the area will be in control for the first half of next week. A
front draws closer from the north for mid week, and may lift
north again late in the week.-- End Changed Discussion --
&&
.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
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At least one more comfortable evening with dew point readings
still relatively low compared to past, and future evenings
ahead. At the surface, a wave of low pressure traverses through
the Canadian Maritimes with high pressure building in from the
west locally in our region.
Min temperatures tonight used a blend of MAV and MET MOS as well as
the NBM, ranging mainly from lower 60s to around 70. Winds are
expected to decrease with gusts diminishing tonight, thereby
allowing for more radiational cooling. Cloud coverage overall is
forecast to be partly cloudy.-- End Changed Discussion --
&&
.SHORT TERM /6 AM SATURDAY MORNING THROUGH SUNDAY/...
***Extreme Heat Watch begins Sunday for much of the region
starting in the afternoon and goes until 8PM Tuesday***
See long term for more details about Sunday night onward.
A building heat ridge develops Sunday and warming temperatures plus
subsidence will lead to the strengthening of this ridge. Hot
temperatures expected with a steady SW flow for much of the area.
High temperatures Sunday are forecast into the 90s for much of
the region of Western Long Island back west through NE NJ, Lower
Hudson Valley and SW CT. Parts of NYC and NE NJ forecast to
reach near 100. Dewpoints forecast to be mostly upper 60s to
near 70. Resulting heat indices reach near 100 to 105 for
locations in the extreme heat watch. The high temperature
forecast used a blend of MAV and MET MOS as well as the NBM.
Uncertainty of a few degrees in temperature and opted to go with
just one headline at this time. Subsequent forecasts could very well
partition this area based on whether heat indices are expected to
reach near 105 versus near 100.
Left out Eastern Suffolk as those locations are expected to be
cooler with more clouds and potentially some showers and
thunderstorms, as well as more maritime influence. Eastern Suffolk
more in the 80 to 90 degree range on average for highs with
corresponding heat indices mostly in the lower 90s and that is just
west of the Forks of Long Island. Forks of Long Island actually
closer to 80 for highs with that more maritime influence.
In the mid levels, a shortwave passes to the northeast of the region
Saturday with strong ridging building in thereafter through Sunday.
Models exhibit a consensus of 500mb heights exceeding 590dm.
High pressure becomes established offshore this weekend. A weak
surface disturbance passes through Saturday with another disturbance
passing by early Sunday. The center of the high pressure area pushes
farther south Sunday in response to a wave of low pressure moving
across Northern New England into the Canadian Maritimes.
In response to the passing disturbances, just enough forcing along
with building low level instability will allow for some showers and
thunderstorms for parts of the region both Saturday and Sunday. Kept
POPs at slight chance with weak forcing and ample dry air in the low
levels. That being stated, there is a conditional probability here
in that there is a marginal risk for damaging winds with some
thunderstorms that develop. Models do show some increase low to mid
level winds this weekend and with the thunderstorm and CAPE which
should easily be achieved with the warmth, that will present more
bulk shear for any thunderstorms.
Max temperatures Saturday well into the 80s. Dewpoints are
forecast to be in the low to mid 60s for much of the region
Saturday. Resulting heat indices just a few degrees above the
actual temperatures well below heat advisory thresholds. Max
heat indices Saturday reach near 90 for some parts of NE NJ.
Rest of the forecast region stays in the 80s for max heat
indices.
&&
.LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/...
Key messages:
* Confidence remains high for the first heat wave of the season
through Wednesday
* Confidence remains below average regarding the full duration of
the heat wave, and whether it lasts late in the week
The first heat wave of the season continues to look more and more
likely with each main model run cycle of the global NWP guidance.
The 500 mb heights look to peak into Monday and Tuesday. Thus during
the course of these two days look for the heat to continue to build.
Excessive Heat Watches remain in effect during this time for a large
majority of the region.
Questions begin to arise towards late Tuesday night into Wednesday
with regard to a frontal boundary north of the area. Blended
consensus guidance continues to indicate that a slow moving cold
front locks up over the area towards later Wednesday into Thursday.
However, based on the 500 mb height consensus forecast there is a
good degree of uncertainty as to how far this frontal boundary can
ultimately push. Any height falls from global NWP guidance appears
to be minimal and without a more potent shortwave feature to the
northwest that can at least temporarily knock down the East coast
heat ridge it may prove difficult to break the heat into mid to late
week. For now have gone closely to the blended guidance Wednesday
into Thursday, and with a frontal boundary suggested to be nearby
have mainly slight chance of shower / thunderstorms for this
timeframe. However, if a more potent shortwave does not show up in
future NWP runs there will be no catalyst to advect cooler air or a
cooler air mass into the region and thus the heat could get extended
further through the week. Was tempted to go warmer than guidance for
Wednesday through Friday with the lack of overall 500 mb height
falls, but will stay closer to consensus guidance for the time
being. The main theme is well above normal temperatures, with very
little if any relief at night (especially in the more urban areas
through at least Tuesday night). Thereafter confidence in forecast
temperatures and heat indices decreases due to uncertainty with the
frontal boundary.
&&
.AVIATION /04Z SATURDAY THROUGH WEDNESDAY/...
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Western Atlantic high pressure will remain in control through
the weekend.
VFR conditions through the TAF period. An isolated shower is
possible Saturday, mainly NW of the NYC metro.
WSW/SW winds continue to diminish to 5 kt or less overnight. A
light WNW-WSW flow to start Saturday morning becomes SW-S into
the afternoon, increasing to 8-12 kt. Seabreeze development is
likely at the coastal terminals, possibly getting to KHPN late.
...NY Metro (KEWR/KLGA/KJFK/KTEB) TAF Uncertainty...
Timing of S sea breezes at JFK and LGA on Saturday afternoon
may be off by 1-2 hours. Winds at EWR and TEB could become S or
SSE with sea breeze passage late Saturday afternoon.
.OUTLOOK FOR 00Z SUNDAY THROUGH WEDNESDAY...
Saturday Night-Sunday. Mainly VFR. Slight chance of showers/thunderstorms
Saturday night into early Sunday. SW wind gusts 15-20 kt on
Sunday.
Monday-Tuesday: VFR.
Wednesday: VFR. Slight chance of showers and thunderstorms in the
afternoon and evening.
Detailed information, including hourly TAF wind component forecasts,
can be found at: https:/www.weather.gov/zny/n90-- End Changed Discussion --
&&
.MARINE...
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Conditions are expected to remain below SCA thresholds on all
waters through Sunday.
Other than marginal small craft seas early Sunday night for the
eastern most ocean waters, expect sub advisory conditions to prevail
on all waters into next week. Ocean seas should settle in around 2
ft Monday and Tuesday, and occasionally up to 3 ft towards mid
week.-- End Changed Discussion --
&&
.HYDROLOGY...
There are no hydrologic concerns through the weekend. Limited
coverage and speed of showers and thunderstorms will not allow
for much rainfall accumulation.
There are no hydrologic concerns through the rest of the
forecast period with dry conditions prevailing.
&&
.TIDES/COASTAL FLOODING...
On Saturday look for a low risk for all ocean beaches with a
diminished swell and lower offshore wave heights. With an
increase in swell and wave heights for central and eastern ocean
beaches look for a moderate risk on Sunday, with a lower risk
for Brooklyn and Queens beaches.
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
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CT...Air Quality Alert from 11 AM Sunday to 11 PM EDT Monday for
CTZ005>012.
Extreme Heat Watch from Sunday afternoon through Tuesday
evening for CTZ005>012.
NY...Extreme Heat Watch from Sunday afternoon through Tuesday
evening for NYZ067>075-078-080-176>179.
NJ...Extreme Heat Watch from Sunday afternoon through Tuesday
evening for NJZ002-004-006-103>108.
MARINE...None.-- End Changed Discussion --
&&
$$
SYNOPSIS...JE/JM
NEAR TERM...JM
SHORT TERM...JM
LONG TERM...JE
AVIATION...DW
MARINE...JE/JM
HYDROLOGY...JE/JM
TIDES/COASTAL FLOODING...