947
FXUS61 KOKX 210740
AFDOKX
Area Forecast Discussion
National Weather Service New York NY
340 AM EDT Sat Jun 21 2025
.SYNOPSIS...
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Western Atlantic high pressure will become more established
through the weekend. A few disturbances will pass through this
weekend. High pressure just southwest of the area will be in
control for the first half of next week. A front will draw closer
from the north on Wednesday and may remain nearby into late week.-- End Changed Discussion --
&&
.NEAR TERM /THROUGH TONIGHT/...
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Generally tranquil conditions are expected today with a departing
trough pulling east of the area with higher heights building in from
the west. High pressure builds south of the area, resulting in
mostly sunny conditions with highs today in the middle to upper 80s.
While no PoPs are in the forecast today and this evening, an
isolated shower can`t be entirely ruled out. A developing SW flow
this afternoon and tonight will advect moisture back into the area.
There is substantial uncertainty with the possible development of a
convective MCS that rides over the northern portion of the developing
ridge. Some CAMs indicate that this MCS that develops over southern
Canada this afternoon may quickly traverse through the Northeast and
may approach the area from the north sometimes late tonight into
Sunday morning. Despite the indication fro a select few models,
opted to not go higher than a slight chance as the potential MCS is
expected to rapidly weaken as it approaches, if it even is able to.
Best chance to see any sort of precipitation would be for areas
north and east, but once again, confidence in the occurrence of this
is much lower than normal at this time frame.-- End Changed Discussion --
&&
.SHORT TERM /SUNDAY THROUGH MONDAY/...
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* Extreme Heat Warning for much of the region from Sunday
afternoon through 8PM Tuesday.
* Extreme Heat Watch remains in effect for NYC, portions of Long
Island, and coastal New London County from Sunday afternoon
through 8PM Tuesday.
By Sunday morning, the development of the ridge will be well
underway with heights continuing to rise aloft and high pressure
strengthening to the south. The uncertainty of any morning
cloud cover or showers from a potential decaying MCS approaching
from the north may result in a temperature forecast that is too high
for Sunday, but given the drier forecast, Sunday is expected to be
the beginning of what may very well be a record setting heatwave for
some locations.
SW flow will continue to allow an advection of low level moisture
Sunday so that dew points climb into the upper 60s and lower 70s.
As the ridge axis approaches the area on Sunday, heights aloft will
continue to increase resulting in generally warmer air aloft. This
should mix down enough to allow surface temperatures to climb into
the 90s for much of the area. Some of the hottest spots near the NYC
metro may approach 100 degrees. Heat index values will be generally
100-105 for much of the area. For areas closer to the coast, heat
index values of 95-100 will be expected.
The heat continues on Monday with temperatures even hotter than
Sunday. High temperatures are expected to once again be in the 90s
though upper 90s is expected for most immediately away from the
coast. temperatures in the low 100s are possible for NE NJ and the
Lower Hudson Valley. Heat Index values Monday will peak in the 105-
110 range inland and 95-105 along the coast.
Lows at night will not offer much relief as low temperatures will
only be in the 70s with more urban locations possibly not dropping
below 80.
Given the expected excessive heat, the Extreme Heat Watch that was
in effect for the inland locations has been upgraded to an Extreme
Heat Warning for Sunday through Tuesday. THe highest heat index
values will occur each afternoon, but especially on Monday and
Tuesday. An Extreme Heat Watch remains in effect for NYC, portions
of Long Island, and coastal New London County in CT.-- End Changed Discussion --
&&
.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
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Key Messages:
* At least one more day of extreme heat/humidity for Tuesday.
* Not quite as hot/humid on Wednesday, but there is some potential
for Wed to be almost as hot as Tue.
* Cold front sagging near/into the area may bring some relief later
in the week.
An anomalously strong heat ridge (H5 heights 599 dm) to start will
very slowly shift south and weaken through the period, eventually
allowing a cold front in response to a closed low over the Atlantic
and shortwave energy streaming across Canada. This will eventually
allow a cold front to sag southward during mid to late week with
chances for diurnal convection.
Tue should be another very hot day, with high temps at or over 100
in NE NJ and parts of the CT River valley, mid/upper 90s most
elsewhere, and cooler near the water in SE CT and across the
forks/south shore of Long Island. Afternoon dewpoints should lower
somewhat via vertical mixing into the mid/upper 60s, but given the
expected heat, max heat index values should surpass 105 in many
inland spots, reach 100-104 in NYC/western Long Island/coastal CT,
and the mid/upper 90s most elsewhere except maybe the south fork of
Long Island. The above numbers come from straight NBM guidance; was
reluctant to go with a blend of the NBM and its 90th percentile
which has worked better for high temps recently because its numbers
get very close to all time high temps at some interior climate sites
such as POU/BDL just outside our CWA. This looks overdone given
model fcst H8 temps, which better support the straight NBM guidance.
Wed still looks hot/humid with high temps 90-95 for NYC metro and
away from the coast, with heat index values a few degrees higher.
There is some uncertainty here, so there is still potential for this
day to be nearly as hot as Tue since NWP guidance often under-
predicts temps on the last day of heat ahead of approaching cold
fronts.
Have cautiously higher confidence in temps/heat index values Thu/Fri
below warning/advy criteria with the front likely remaining in the
vicinity, bringing diurnal convection both days.-- End Changed Discussion --
&&
.AVIATION /07Z SATURDAY THROUGH WEDNESDAY/...
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VFR with high pressure in control.
Light WNW-WSW flow to start should become SW-S into the afternoon,
increasing to 8-12 kt. Sea breeze development is likely at the
coastal terminals, getting to KHPN late.
...NY Metro (KEWR/KLGA/KJFK/KTEB) TAF Uncertainty...
S-SE harbor breeze should hold just E of KEWR this afternoon, but
may make it in there and at KTEB toward 00Z Sunday.
.OUTLOOK FOR 06Z SUNDAY THROUGH WEDNESDAY...
Late Saturday night: VFR.
Sunday: Slight chance of showers/tstms mainly in the morning. WSW-SW
winds G15-20kt in the afternoon.
Monday and Tuesday: VFR.
Wednesday: Chance of showers/tstms in the afternoon/evening mainly
for KHPN/KSWF.
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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Other than some 5-ft seas late day Sunday into Sunday evening
for the ocean waters E of Moriches Inlet, sub-SCA conditions
expected through Wed night. Ocean seas should settle in around
2 ft on Monday.-- 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...
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Low risk for rip currents 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.-- End Changed Discussion --
&&
.CLIMATE...
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Increasing heat may result in record high temperatures Sunday
through Tuesday.
Sunday`s Record Highs (June 22):
EWR 101/ 1988
BDR 93 / 1949
NYC 98 / 1988
LGA 99 / 1988
JFK 94 / 2012
ISP 94 / 2012
Monday`s Record Highs (June 23):
EWR 99 / 2024
BDR 91 / 2010
NYC 96 / 1888
LGA 95 / 2024*
JFK 94 / 2010
ISP 91 / 1999
Tuesday`s Record Highs (June 24):
EWR 97 / 1966
BDR 94 / 1966
NYC 96 / 1888
LGA 96 / 2013
JFK 97 / 2010
ISP 96 / 1966-- End Changed Discussion --
&&
.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 Warning from noon Sunday to 8 PM EDT Tuesday for
CTZ005>010.
Extreme Heat Watch from Sunday afternoon through Tuesday
evening for CTZ011-012.
NY...Extreme Heat Warning from noon Sunday to 8 PM EDT Tuesday for
NYZ067>071.
Extreme Heat Watch from Sunday afternoon through Tuesday
evening for NYZ072>075-078-080-176>179.
NJ...Extreme Heat Warning from noon Sunday to 8 PM EDT Tuesday for
NJZ002-004-006-103>108.
MARINE...None.-- End Changed Discussion --
&&
$$
SYNOPSIS...BG/MW
NEAR TERM...MW
SHORT TERM...MW
LONG TERM...BG
AVIATION...BG
MARINE...BG/MW
HYDROLOGY...BG/MW
TIDES/COASTAL FLOODING...
CLIMATE...