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364
FXUS61 KOKX 271132
AFDOKX

Area Forecast Discussion
National Weather Service New York NY
732 AM EDT Thu Aug 27 2026

.WHAT HAS CHANGED...
There have been no significant changes to the
forecast. The threat for severe thunderstorms this afternoon/evening
has increased somewhat. A flood watch remains in effect until 11pm
tonight for the Lower Hudson Valley, NE NJ, NYC, Nassau County and
Fairfield County.

&&

.KEY MESSAGES...
1) Periods of heavy rainfall and scattered thunderstorms are likely
today into early Friday, mainly for NYC and areas north and west.
Isolated instances of flash flooding and scattered strong to severe
thunderstorms are also likely, particularly west of the Hudson
River.

2) After another chance of thunderstorms on Friday, a dry and
seasonable forecast for the weekend, with a warming trend early next
week.

3) High risk for rip currents at the Atlantic facing beaches today.

&&

.DISCUSSION...
.KEY MESSAGE 1...
The ingredients continue to come together for
periods of heavy rainfall and isolated to scattered severe
thunderstorms this afternoon into early Friday.

Latest 6.95um WV imagery shows an upper low rotating over Hudson Bay
with multiple vort maxes surging through the Great Lakes and OH
Valley around the base of a mid level open trough. The region
remains on the eastern side of this trough, with deep southwest flow
advecting in moisture from the southeast US. Under this
southwesterly flow, PWATs will increase to about 1.75" under the
southerly flow, which is high (near or above the 90th percentile for
8/27 per SPC sounding climo) but not as high as previous events this
summer.

Surface low pressure with a slowly moving frontal system accompanies
this feature, and approaches the local area later this morning.

A pre-frontal trough sets up along or northwest of the i-95 corridor
this afternoon and looks to be the focus for convective activity.
The 00Z CAMS continue to vary in convective coverage, but do now
point to somewhat less activity this morning and focus more on
rounds of showers and storms this afternoon. However, State College,
PA WSR-88D is depicting some early development this morning over SE
PA which will have to be watched over the next several hours as
they head northeast.

The convective mode looks somewhat disorganized, generally, making
it difficult to pinpoint who might receive the heaviest rainfall
this afternoon. Areawide amounts from the NBM and global model suite
look to be in the range of 0.5"-1.0" through 12Z Friday; highest
amounts across the LoHud and NE NJ. There continues to be a sharp
gradient to the east, with perhaps some east of NYC not picking up
much precipitation at all. The 00Z HREF and other 00Z CAM guidance
has an PMM area of 10% of >3"/3 hrs during the event, suggesting
that any flash flooding may be more isolated in nature. However,
some CAM guidance is showing isolated amounts of 3-4", along and
just NW of i-95, so the potential remains for those higher amounts
somewhere in that vicinity. RFCFFG depicts northeast NJ and Rockland
County as the most vulnerable spots for flash flooding based on
antecedent conditions. Less than 1" in an hour, and 1.5" - 2" in
three hours for those areas. CAMs do show higher probabilities for
>1-2" an hour across NE NJ and the LoHud, adding confidence to the
flash flooding potential there. So with all this, will maintain
the existing flood watch both in space and time, and highlight
the axis from NE NJ into the LoHud as having the highest
likelihood for flash flooding impacts this afternoon. However,
anyone in the watch area has the potential to experience heavy
downpours and flooding as the convection works through.

WPC has expanded their Slight Risk (2/4) of excessive rainfall a bit
further east, which now aligns with the flood watch and includes NYC
and parts of western Long Island. A Marginal Risk (1/4) continues
for most of the rest of the area, except far eastern Long Island and
SE CT.

The threat for more widespread severe thunderstorms has increased
somewhat by this afternoon with model soundings showing both decent
instability (~1500-2500J/kg MUCAPE) and 0-6km shear in the 30-40kt
range, so cannot rule out an isolated to scattered severe
thunderstorms. Wind gusts would be the main hazard associated with
the strongest storms, with DCAPE progged to be in the 500-1000 J/kg
range. An isolated tornado or two is also possible given favorable
hodographs and increased low level directional shear. 00Z HREF
maintains STP values between 1-2, and 2-5km updraft helicities
maximized across the Lower Hudson Valley this afternoon.

SPC maintains a Slight (2/5) Risk for Severe Weather across western
portions of the area, becoming Marginal (1/5) for NYC, Nassau, and
Fairfield.

.KEY MESSAGE 2...
Cold pool aloft with main cold frontal passage Friday may spark a
few afternoon showers and thunderstorms, especially across southern
CT and and LoHud. Coverage looks isolated and mainly sub severe, at
this point.

Otherwise, mainly zonal flow behind the late week system turns into
weak ridging by late Saturday into Sunday as heights aloft rise.
Skies will clear with northerly flow on Saturday, and dry conditions
lasting into Sunday. Winds turn southerly on Sunday as the sfc high
moves offshore, and dewpoints climb a few degrees relative to
Saturday. Otherwise, near to slightly below normal temperatures both
days, with highs in the upper 70s to lower 80s. Heights continue to
build into early next week, with increasing temperatures.  Heat
indices may approach 90F for the urban corridor Monday and Tuesday.


.KEY MESSAGE 3...
Winds increase today out of the S closer to 15-20 kt. This
combined with a building swell of 3-4ft at 5s out of the S/SE
will bring a high risk of rip currents. The risk through much of
the day may end up being moderate for southeast Suffolk, but
high is possible by the late afternoon/evening.

&&

.AVIATION /12Z THURSDAY THROUGH MONDAY/...
A frontal system approaches from the west tonight and impacts
the region on Thursday.

A line of showers and thunderstorms over northern NJ will move
east this morning and should affect the metro terminals around
12Z today, bringing MVFR or lower conditions. Thereafter, the
potential exists for showers and thunderstorms throughout the
day, but exactly where and when they occur is uncertain, and so
there are multiple TEMPO groups to cover this potential. Since
thunder is occurring so early this morning, it`s reasonable to
think that any area of showers that moves through will have
embedded thunderstorms associated with them. There is a chance
for widespread MVFR or lower in fog and/or stratus tonight at
all airports, mainly after midnight, and better chances across
eastern/outlying terminals.

Generally S winds 10 kt or less tonight. Winds increase
Thursday to around 10-15 kt with some gusts into the upper
teens and lower 20 kt range. Winds decrease below 10 kt aft 00Z
Fri and shift more toward the SW/SSW, with outlying terminals
becoming light and variable.

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

Confidence in the exact timing and placement of any tstms on
today is low.

Some of the tstms could produce winds in excess of 50 kt, as
well as hvy rain reducing visibility to below 1 SM.

.OUTLOOK FOR 12Z FRIDAY THROUGH MONDAY...

Friday: Mainly VFR. MVFR or lower at times w/SHRA and TSRA.

Saturday-Sunday: VFR.

Monday: Mainly VFR. MVFR or lower in any showers or
thunderstorms, mainly across NE NJ and the Lower Hudson Valley.

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

&&

.MARINE...
Sub small craft conditions are expected through the week.

Southerly flow increases late Wednesday night into Thursday, with
ocean seas getting to around 4 ft and gusts approaching 20 kt.
Otherwise, sub advisory conditions prevail with seas and winds
diminishing for the weekend with a light pressure gradient with high
pressure building across for the weekend.


Rip Currents:

A moderate risk continues today with a weak swell component and
around 10-15 kt S/SW winds.

Winds increase on Thursday out of the S closer to 15-20 kt. This
combined with a building swell of 3-4ft at 5s out of the S/SE will
bring a high risk of rip currents. The risk through much of the day
may end up being moderate for southeast Suffolk, but high is
possible by the late afternoon/evening.

The risk lowers back to moderate on Friday with a lingering 3ft 6s
swell out of the SE.

&&

.OKX WATCHES/WARNINGS/ADVISORIES...
CT...Flood Watch from noon EDT today through this evening for
     CTZ005-009.
NY...Flood Watch from noon EDT today through this evening for
     NYZ067>075-176>179.
     High Risk for Rip Currents through this evening for NYZ075-080-081-
     178-179.
NJ...Flood Watch from noon EDT today through this evening for
     NJZ002-004-006-103>108.
MARINE...None.

&&

$$

DISCUSSION...DBR
AVIATION...JP
MARINE...DBR

Previous Forecast Discussions may be found at
NWS New York City/Upton, NY (OKX) Office Forecast Discussions.
(Click 'Previous Version' there to view past versions successively.
Some may differ only in time posted.)

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