Groton, Connecticut 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

831
FXUS61 KOKX 060025
AFDOKX

Area Forecast Discussion
National Weather Service New York NY
825 PM EDT Fri Sep 5 2025

.SYNOPSIS...
A strong cold front will impact the area Saturday, and pass offshore
Saturday night. High pressure builds in late Sunday and remains in
control through much of next week. A cold front approaches late
next week.

&&

.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
High pres will remain over the Atlc tngt, keeping a return sly flow
in place. This will allow for humidity to build, and for some fog to
develop overnight. Winds look like a limiting factor for fog
development, so kept coverage as patchy. Otherwise, no pcpn is
expected, and the fcst follows the NBM closely.

&&

.SHORT TERM /6 AM SATURDAY MORNING THROUGH SATURDAY NIGHT/...
A cold front will likely bring a round of severe weather to the area
on Sat.

With sufficient moisture and daytime heating, SBCAPE is modeled to
increase to around 2500 J/kg during the day on Sat from
approximately NYC to points N and W, including wrn CT. Veering winds
with height, with about 40kt at h85, yield a BRN around in the 15-30
range, indicating organized development with the potential for some
supercells. Damaging winds possible in any of these areas with the
cdfnt providing focus by 16-18Z. In addition, 0-3km ehi over 2-3
from near POU swwd thru the cwa indicates a tor risk as well.
Storm mode favors discrete and supercellular storm modes with
Supercell composite values above 3 nearby and just north of NYC.
SPC has the area in a slight risk, and the gridded fcst includes
severe wording along with the hwo.

Across ern areas, the front will be later, and the area will be a
bit more stable per the progs per the maritime sly flow. Cntrl and
ern CT N of the immediate coast will be a challenge wrt how high
CAPE gets because of this. The NAM keeps the highest CAPE confined
to just the extreme nrn border of the CWA, so the svr risk may
extend a bit later in the day in this zone.

Heavy rain a risk as well, with pwats modeled to increase to around
2.5 inches in the llvl convergence zone. Storm motion however is
progged to be around 15kt, potentially limiting the flash flood
threat. See the hydrology section for more details.

A bit breezy on Sat ahead of the tstms with deep swly flow. Went
abv the NBM in the grids during the day.

The front is progged to slide completely offshore around 6Z, so
this will end any residual severe threat. There will be chances for
additional shwrs or lgt rain however with the area in the rr quad of
the jet.

&&

.LONG TERM /SUNDAY THROUGH FRIDAY/...
Key Points:

*Trending toward more clouds and rain for Sunday, especially
 Long Island and CT.

*Mainly dry with below normal temperatures next week.

An anomalously strong upper trough lifts out to the Northeast
Sunday into Monday. Post-frontal rain will linger at least
through the first half of Sunday, especially across eastern
LI/SE CT. However, 12Z GFS showing decent deep-layered lift
behind the cold front both due to upper jet dynamics and strong
frontogenesis. Latest NBM which was followed has also trended
slower with exiting the rain on Sunday. This is where the
forecast change could be impactful. Otherwise, heights build
next week with another large high pressure system building into
the area and holding on for much of the week. Temperatures will
be on the order of 5 to 10 degrees below normal during the period.
Due to the aforementioned trends, Sunday could be cooler than
forecast.

In addition, building heights aloft through midweek will allow
the western Atlantic subtrop ridge to build closer to the east
coast. This will allow the forecast area to be close to the NW
periphery of some offshore frontal wave activity. Latest
forecast has low rain chances across LI and SE CT on Wednesday
with an increase in cloud cover across the area.

A late week cold front will bring another shot of cooler air for
next weekend.

&&

.AVIATION /01Z SATURDAY THROUGH WEDNESDAY/...
A cold front approaches tonight, getting into western portions of
the area Saturday afternoon, and further east across the area
Saturday evening / night.

VFR for tonight for most terminals. Some outlying terminals may see
some MVFR conditions with low stratus and fog just before sunrise
Saturday. There is a low chance that this may push into some of the
metro terminals late tonight, however confidence of occurrence
remains too low at this time to include for these terminals. Showers
and thunderstorms will approach towards midday. KSWF will see a
higher chance for thunder and showers earlier, and thus a PROB30 is
in place at KSWF for 16Z-18Z Saturday. There remains a low chance
they will affect the metro terminals this early, with better chances
after 18Z, and more likely towards 19-20z Saturday for the city
terminals, accompanied with MVFR conditions or lower.

Winds remain southerly overnight, but remain elevated, between 10 kt
to 15 kt, with lower winds for the outlying / interior terminals.
Southerly flow continues for Saturday 10 kt to 15 kt, with gusts 20
to 25 kt. As the front approaches later in the day and early evening
look for a wind shift, especially in any thunderstorms to the NW.
Otherwise, with the boundary settling nearby the winds likely go
variable in direction late in the TAF period for the city terminals
Saturday evening.

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

There is a low chance of MVFR or lower with fog and low stratus
overnight, mainly for KJFK, however confidence is not high enough to
include in TAFs. There remains some uncertainty with the timing of
the arrival of showers and thunderstorms Saturday afternoon with
amendments becoming increasingly likely late in the day and into the
evening.

.OUTLOOK FOR 00Z SATURDAY THROUGH TUESDAY...

Saturday night: Cold frontal passage with thunderstorms likely early
with wind shift and gusts in any storms, followed by a period of
showers later at night. Winds become NW and N at mostly 5 to 10 kt
late.

Sunday: MVFR or lower possible in the morning becoming VFR in the
afternoon from west to east.

Monday and Tuesday: VFR.

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

&&

.MARINE...
S winds will increase tngt, so with building seas, a SCA has
been issued for the ocean. Winds will be close to SCA lvls
elsewhere on Sat, particularly ern waters. In addition, strong
tstms ahead of a cdfnt will impact the waters, especially wrn
portions, Sat aftn and into the eve.

Sub-advisory conditions are expected Sunday through Tuesday as
high pressure builds into the area. Easterly winds will
strengthen on Tuesday due to a tightening pressure gradient
across the waters. E winds could gusts up to 20 kt on the ocean
waters with seas building to around 4 ft. There is a chance
that an E swell could help seas increase to around 5 ft on
Wednesday.

&&

.HYDROLOGY...
A general 1-2 inches of rain is expected Sat and Sat ngt,
particularly across the wrn 2/3 of the area. Areas of minor urban
and poor drainage flooding can be expected. There is a localized
flash flood risk as well, especially if storms concentrate over the
more flood prone areas of NJ, or if areas are impacted by numerous
rounds of activity.

Lingering post-frontal rain on Sunday does not look to pose a
flood threat at this time.

&&

.TIDES/COASTAL FLOODING...
There is a high rip current risk through Saturday evening due to
a combination of a strong onshore flow (S 15-20kt) and
southerly wind waves of 4-5ft 6S. For Sunday, the risk at the
very least will be moderate, and possibly high with a building
southerly swell of 3-4ft 7-8S. However, winds will be less of a
factor due to being offshore and generally less than 10 kt.

&&

.OKX WATCHES/WARNINGS/ADVISORIES...
CT...None.
NY...High Risk for Rip Currents through Saturday evening for NYZ075-080-
     081-178-179.
NJ...None.
MARINE...Small Craft Advisory until 6 PM EDT Saturday for ANZ350-353-
     355.

&&

$$

SYNOPSIS...JMC/DW
NEAR TERM...JMC
SHORT TERM...JMC/JE
LONG TERM...DW
AVIATION...JE
MARINE...JMC/DW
HYDROLOGY...JMC/DW
TIDES/COASTAL FLOODING...