Groton Long Point Connecticut Weather Forecast Discussion

143
FXUS61 KOKX 062320
AFDOKX
Area Forecast Discussion
National Weather Service New York NY
720 PM EDT Mon Oct 6 2025
.SYNOPSIS...
High pressure will move offshore through Tuesday. A cold front
approaches Tuesday night and passes through late Tuesday night
into early Wednesday. Strong high pressure then builds in from
Wednesday night through early Friday. The high pressure
weakens into the weekend and potentially gives way to an
approaching low for the latter half of the weekend into early
next week.
&&
.NEAR TERM /THROUGH TUESDAY/...
High pressure moves offshore tonight into Tuesday, as the upper
ridge axis also moves further east of the region. South to
southwest winds will remain through the night, but weaken with
increasing high cloudiness. This combination will keep
temperatures slightly higher than Sunday night/Monday morning.
Stronger flow above the surface and turbulent mixing will keep
radiational fog from developing. While there may be some
valley/river fog, especially across the interior, widespread fog
is not expected. The NBM and MAV/MET guidance look reasonable
for overnight lows. And highs Tuesday will be a few degrees
lower than the previous days. Also leaned toward the NBM and
MAV/MET guidance for highs. With the approach of the front
showers should hold off until Tuesday evening.
&&
.SHORT TERM /TUESDAY NIGHT THROUGH WEDNESDAY/...
Showers move in with the cold front Tuesday night and Wednesday,
and will be fairly quick moving, and precipitation could be
ending across eastern Long Island before dark. Have removed the
mention of thunder as any that may occur will be isolated, and
mainly across northeastern New Jersey into NYC, and the chances
will be during a brief period around daybreak Wednesday.
Elevated CAPE is minimal, with little to no instability.
Isolated convective cells could also produce briefly heavy
rainfall and will be enhanced with a low level jet of 35 to 45
kt, and precipitable water increasing to around 1.75 inches.
With a rather quick movement of the front, leaned toward some
of the faster CAMs, along with the NBM. Hydrologic issues are
not expected, see HYDROLOGY section.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/...
Key Points
* Very cool airmass moving in Wednesday night into early Friday,
  possible frost for parts of the interior early Friday morning.
* Potential coastal storm for the latter half of the weekend, with
  potential for gusty winds and widespread rain.
Wednesday night through early Friday, a trough exits and ridge
builds aloft. At the surface, a strong 1030+mb high builds
southeast into the region from Southeast Canada and the Great
Lakes. This high pressure area will center across the local area
late Thursday night into early Friday morning.
Dry conditions with cooler temperatures expected with new
airmass building in Wednesday night through early Friday. Models
indicate relatively coldest air at 850mb arrives Wednesday
night into early Thursday. However, surface temperatures will be
limited from plummeting too much due to the boundary layer and
winds staying up.
Much cooler than normal temperature setup for Thursday and
Thursday night. Cold air will advect in from the north Thursday
with gusty northerly flow, with forecast highs only in the upper
50s to lower 60s, roughly 10 degrees below normal. For Thursday
night with the decrease in pressure gradient as high pressure
settles overhead, northerly winds become very light to calm and
sky conditions will be mostly clear, setting up efficient
radiational cooling.
Already noting MEX guidance and NBM 50th percentile lower than
NBM alone, went with a blend of NBM 50th percentile and NBM for
low temperatures Thursday night. This results in temperatures
slightly colder than NBM alone. The range of lows is from the
lower 30s in outlying areas within interior to upper 40s within
much of NYC. Across parts of the interior, there will be
potential for some frost to form.
Ridge axis shifts east of the region aloft Friday into Friday
night. Cutoff low aloft develops and approaches from the south
and west for the weekend. Models indicate an approaching surface
low pressure from the south for the weekend.
Models are conveying a consensus of growing chances for rain
associated with the closer proximity of the low. The low has
potential to be a strengthening coastal low. Went with NBM and
higher percentiles of NBM (75th and 90th) for the winds to
reflect the steeper pressure gradient. Forecast has trended
wetter with more winds especially for the second half of the
weekend. Subsequent cycles of models will need to be monitored
for positions and strength of the low and nor`easter potential.
&&
.AVIATION /00Z TUESDAY THROUGH SATURDAY/...
High pressure will continue to move offshore through Tuesday. A
cold front approaches Tuesday night.
Mainly VFR through the TAF period. IFR, potentially LIFR
conditions are expected to develop at KGON late tonight/early
Tuesday morning with a lower chance for MVFR-IFR at KISP.
S winds around 10 kt to start will diminish this evening,
becoming SW around 5 kt or less overnight. SW-S winds increase
Tuesday morning, becoming 10-13 kt with gusts around 20 kt in
the afternoon.
Showers may begin developing after 03z Wednesday from NYC
terminals on north and west.
...NY Metro (KEWR/KLGA/KJFK/KTEB) TAF Uncertainty...
Wind speeds could remain around 10 kt a few hours longer this
evening at KJFK and KLGA. An occasional gust at KLGA possible
through 01z.
Timing of gusts on Tuesday may be off by 1-3 hours.
.OUTLOOK FOR 00Z WEDNESDAY THROUGH SATURDAY...
Tuesday night-Wednesday: MVFR, possibly IFR at times, with
showers, ending Wednesday afternoon. VFR returns Wednesday
afternoon and evening. NW-N wind gusts 15-20kt Wednesday
afternoon into night.
Thursday: VFR. N gusts 15-20 kt possible in the morning.
Friday-Saturday: VFR. Slight chance of showers late Saturday.
Detailed information, including hourly TAF wind component
forecasts, can be found at: https:/www.weather.gov/zny/n90
&&
.MARINE...
With retreating high pressure and the approach of a cold front
during Tuesday, occasional wind gusts will be nearing 25 kt by
late Tuesday afternoon across the western ocean waters, and then
into Tuesday night across the eastern ocean waters. In addition,
with an increasing southerly flow, ocean seas will be building
to SCA levels by late Tuesday night. There is still some
uncertainty as to how high winds and gusts will be over the
ocean waters, and with seas building later in the third period,
will hold off on issuing an advisory. Ocean seas may remain at
SCA levels through much of Wednesday and then fall below with a
northwest to north flow behind a cold front passing east early
Wednesday.
SCA wind gusts on at least the ocean waters for Wednesday night
into early Thursday. Potential widespread SCA level wind gusts,
approaching gales for Saturday night, mainly late.
SCA level ocean seas forecast Wednesday night and Thursday,
then below SCA for Thursday night through Saturday morning.
Thereafter, ocean seas build in advance of low getting above SCA
thresholds, maybe even up to near 10 to 12 ft by late Saturday
night.
&&
.HYDROLOGY...
Rainfall with a cold front passage Tuesday night through
Wednesday could range from around 3/4`s of an inch to as much as
1 1/4 inches, with the highest amounts across southeastern
Connecticut into eastern Long Island. There is the potential
for isolated and brief heavy rainfall late Tuesday night into
early Wednesday. At this time no hydrologic issues are expected.
Uncertainty increases this weekend with a potential coastal low,
but at this time no hydrologic impacts are expected.
&&
.TIDES/COASTAL FLOODING...
Tuesday morning looking like total water levels end up being
less than minor coastal flood benchmarks from recent surge
guidance. However, there is potential for minor coastal flooding
mid to late week and even perhaps late this weekend.
The recent Stevens surge model guidance indicates potential for
minor coastal flooding for early Wednesday high tide cycles but this
is more from the higher end portions of the NY HOPS ensemble.
Also indicating potential for minor coastal flooding early
Wednesday is the ESTOFS. ETSS has lower total water levels and
thereby less than minor coastal flood benchmarks.
Surge models showing a greater potential for higher total water
levels for early Thursday high tide cycles from the ESTOFS, ETSS and
Stevens and chances for coastal flooding. However, northerly flow
Thursday morning could very well limit the total water levels.
Stevens also showing potential for higher total water levels for
early Friday high tide cycles with another chance for coastal
flooding.
There is a recent full moon leading to the higher astronomical
levels with only around a half foot needed for the astronomical
departures to reach minor coastal flooding. Potentially leading to
water levels being higher early Friday is the switch to more
easterly flow forecast on Friday. At this point, the potential is
mainly for minor coastal flooding in the more vulnerable areas for
coastal flooding along the shorelines of Western Long Island Sound
along Southern Fairfield CT as well as the South Shore Bays of Long
Island looking at Wednesday through Friday.
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
CT...None.
NY...None.
NJ...None.
MARINE...None.
&&
$$
SYNOPSIS...JM/MET
NEAR TERM...MET
SHORT TERM...MET
LONG TERM...JM
AVIATION...DS
MARINE...JM/MET
HYDROLOGY...JM/MET
TIDES/COASTAL FLOODING...

NWS OKX Office Area Forecast Discussion