517
FXUS61 KOKX 182030
AFDOKX
Area Forecast Discussion
National Weather Service New York NY
430 PM EDT Wed Jun 18 2025
.SYNOPSIS...
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A warm front struggles north of the region through this
evening. A cold front approaches late Thursday and moves across
the region Thursday night. High pressure builds Friday and into
the weekend. Bermuda high pressure will then settle just south
of the region for the first half of next week.-- End Changed Discussion --
&&
.NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
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A warm front struggles north of the region through this
evening. Stratus/dense fog bank across the ocean likely works
back along immediate southern and eastern coastal areas this
evening, which may bring areas of dense fog to coastal areas.
Marginal to borderline moderate surface instability for areas
west of the Hudson River, away from marine influence. Combined
with weak upper energy approaching from the SW this eve and
marginal deep layer shear, isolated to widely scattered
thunderstorms expected to slide east into the LoHud and NE NJ
through early this evening.
The severe thunderstorm threat is very marginal (less than 5%
prob for LoHud and NE NJ). Any showers and thunderstorms that
develop have the potential of producing heavy rainfall, as the
storm will be relatively slow moving (east at 20-25 mph) with
near record PWATS of 2 1/2". Isolated to widely scattered storm
coverage should limit flash flood threat to very marginal (less
than 5% prob for NYC and moreso points NW, W, SW).
Thunderstorm potential and intensity decreases working eastward
this eve through NYC/SW CT into LI/E CT with greater maritime
influence.
Weak shortwave surface/aloft slides east this evening bringing
shower/thunderstorm threat to an end. Region will become warm
sectored under a warm and muggy airmass. Light S/SW flow of
high Td airmass over low 60 degrees waters point towards
continuation of maritime stratus/fog across southern and eastern
coastal areas. Patchy fog threat elsewhere.-- End Changed Discussion --
&&
.SHORT TERM /6 AM THURSDAY MORNING THROUGH THURSDAY NIGHT/...
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* Hot and Humid on Thursday with late afternoon/evening
scattered severe thunderstorm threat *
Fairly deep Great Lakes/Ohio valley shortwave trough approaches
from the west on Thursday aft/eve, with resultant developing
low pressure tracking ne along the St Lawrence River Valley into
southern Quebec on Thursday, and associated pre-frontal trough
approaching late Thu afternoon/evening.
Coastal morning stratus/fog should quickly dissipate Thursday
morning with strengthening deep SW flow. Deep mixing to at least
850mb (850mb T around 19C) will lend to widespread temps in the
lower 90s areas away from south and east coast. Potentially
approaching 95F for urban NE NJ, mid to upper 80s for south and
east coasts. Tds will also be on the increase. 75 F Tds noted
in mid-Atlantic/south Jersey this afternoon pooling up against
the warm front. Sounding indicated some drying aloft Thursday,
but lower 70s Tds seen in NBM, HRRR and MOS guidance are quite
reasonable, with worst case of 75F Tds. One day of mid to upper
90 heat indices likely for NYC/NJ metro, LoHud, and interior Sw
CT, with heat indices around 90 F for south and east coastal
areas. Southwesterly wind gusts increase to 25 to 30 mph in the
afternoon.
Shortwave approach in late afternoon, encountering a moderately
unstable and deeply sheared environment, should allow for
scattered multi-cell and supercell development along/ahead of
the pre-frontal trough across central NY/PA in the early
afternoon. This activity should work east towards the region in
the late afternoon/evening, with organization into a bowing line
segment or two possible. Scattered severe storms are possible
(SPC-WFO coordinated slight risk for the area) with damaging
wind gusts the primary threat (15% probability of occurrence w/i
25 miles of a point), particularly with any bowing segment
development. There is a marginal risk of large hail (5%
probability of occurrence w/i 25 miles of a point) with any
supercell/multi cluster activity, and an isolated tornado threat
(2% probability of occurrence w/i 25 miles of a point) along
bowing segments or supercells. Farther east across LI/CT,
expectation is that storms should gradually weaken in intensity
after 8pm as storms encounter a stabilizing environment.
With the passage of the cold front Thursday night the showers and
thunderstorms will end. High pressure then builds toward the region
for Friday, with slightly cooler temperatures.-- End Changed Discussion --
&&
.LONG TERM /FRIDAY THROUGH WEDNESDAY/...
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* PATTERN CHANGE TO HOT AND HUMID CONDITIONS BY EARLY NEXT WEEK *
Expect a significant long wave pattern change for the period. A
shortwave feature exits Northern New England and SE Canada
early on Friday. In its wake gradual height rises are expected
to take place for the most part beginning Friday and into the
weekend. Much of the NWP global guidance is suggestive of a
shortwave feature which attempts to ride and break through the
northern portion of the building ridge. This will be a transient
feature as questions remain as to how this feature will track
and whether its effects will be mainly north of the CWA towards
the middle of the upcoming weekend. For now have covered this
feature with slight chance to low end chance PoPs. In any event,
the turn to a hot and humid regime looks likely into early next
week as higher heights and thicknesses build across the region.
The warm up is expected to begin to build by late Sunday,
especially for western and southwestern most areas.
Hot and humid conditions thus are likely to prevail Monday
through Wednesday with primarily dry weather as any shower /
t-storm activity is likely to remain west and northwest of the
region. At this time it appears that a good portion of the
region will experience the first heat wave of the season, with
less certainty further east. Regardless, temperatures will
average well above normal into next week. Towards the tail end
of the period (say mid to late week) if the ridge break downs
enough, the chance of diurnally driven convection would increase
and could introduce some chance of late day and early evening
showers and t-storms.-- End Changed Discussion --
&&
.AVIATION /20Z WEDNESDAY THROUGH MONDAY/...
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Warm front will weaken as it moves through the region this
afternoon into evening.
For NYC terminals, KHPN, and KSWF, forecast has MVFR to VFR into
early evening, until around 00-01Z Thursday. However, within
this timeframe is when showers redevelop and move in along with
some embedded thunderstorms. Thunderstorms have timing of 21Z
Wednesday to 01Z Thursday. These could temporarily lower
conditions back down to MVFR to IFR for a short time. MVFR to
LIFR clouds and fog redevelop tonight and last into Thursday
morning. VFR forecast to return by late Thursday morning and
into Thursday afternoon.
For KBDR, KISP and KGON, initial conditions vary from VFR to
IFR. For these terminals, showers are still forecast mainly in
that 21Z to 03Z time window, but thunderstorms are a lower
chance. Left PROB30s for thunder for KISP and KGON (00-03Z
Thursday) and left out of KGON. For tonight, fog and low
stratus are likely with LIFR forecast into Thursday morning.
Some improvement is expected late Thursday morning into
afternoon to MVFR but not for KGON which remains LIFR to
potentially IFR.
Winds will be generally southerly at or less than 10 kt through
much of the TAF period. Winds become more SW 10-15 kt for
Thursday afternoon. Some terminals will have more variable wind
direction during times when wind speeds are at or less than 5
kts.
...NY Metro (KEWR/KLGA/KJFK/KTEB) TAF Uncertainty...
KLGA Sound breeze with NE winds near 5-7 kts possible at times
before 22Z this evening.
Amendments likely. Categories may vary between MVFR and LIFR at
times tonight into Thursday morning.
Shower and thunderstorm timing could vary by 1-2 hours compared
to TAF.
.OUTLOOK FOR 18Z THURSDAY THROUGH MONDAY...
Thursday: Lower clouds and fog scatter out with VFR by early
afternoon for most terminals. KGON may take until late afternoon.
Showers/tstms with MVFR to IFR then possible in the late
afternoon/early evening, some with locally strong winds from the
NYC metros north/west. Otherwise winds are SW near 10-15 kt with
gusts near 20 kt afternoon into evening before diminishing late
at night.
Friday through Monday: Mainly VFR.
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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A Dense Fog Advisory continues for ocean waters east of Fire Island,
southern and eastern bays of LI, and E LI Sound with stratus/dense
fog deck over lower 60 F waters (visibilities less than 1 NM). This
deck may back west for a bit late this afternoon and evening.
Winds and seas remain below advisory levels today into Thursday
morning, then with an increasing southwest flow ahead of a cold
front Thursday occasional gusts to near 25 kt are likely on the
ocean waters and southern bays. As a result ocean seas will likely
build to around 5 feet late Thu into Fri AM. Behind the cold front,
NW gusts are expected to run below 25 kt.
Winds and waves are expected to fall below Small Craft Advisory
criteria Friday afternoon and continue through early next week.
Ocean seas should settle in around 2 ft, occasionally up to 3
ft during the weekend and into early next week.-- End Changed Discussion --
&&
.HYDROLOGY...
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One quarter to three quarters of an inch rain, with locally higher
amounts, is possible across the lower Hudson Valley, northeastern
New Jersey, and New York City into this evening. The probability for
flash flooding is marginal (around 5% probability), with a higher
probability across central NJ.
Once again a marginal risk of flash flooding (around 5% probability)
on Thursday, with scattered locally heavy downpours and
thunderstorms late Thursday afternoon into the evening. The quicker
storm motion as compared to today, will limit the flash flood threat
to any localized areas of training.
There are no hydrologic concerns Friday through early next
week.-- End Changed Discussion --
&&
.TIDES/COASTAL FLOODING...
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There will be a moderate rip current risk during the morning on
Thursday, before increasing to a high risk later in the day for the
western ocean beaches. A moderate risk is expected for the Suffolk
ocean beaches for Thursday. On Friday the high risk should continue,
at least through the morning for the western ocean beaches. The high
risk on Friday will likely continue for the eastern ocean beaches
through a good portion of the day on a lingering 5 ft near buoy wave
height on a south to southeast 7 second wave period.-- End Changed Discussion --
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
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CT...Air Quality Alert from 11 AM to 11 PM EDT Thursday for
CTZ005>007-009>011.
NY...High Risk for Rip Currents from Thursday afternoon through Thursday
evening for NYZ075-178-179.
NJ...None.
MARINE...Dense Fog Advisory until 8 AM EDT Thursday for ANZ331-332-340-
345-350-353.
Dense Fog Advisory until 8 AM EDT Thursday for ANZ335.-- End Changed Discussion --
&&
$$
SYNOPSIS...JE/NV
NEAR TERM...NV
SHORT TERM...NV
LONG TERM...JE
AVIATION...JM
MARINE...JE/NV
HYDROLOGY...JE/NV
TIDES/COASTAL FLOODING...JE