Groton, Connecticut 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

785
FXUS61 KOKX 060905
AFDOKX

Area Forecast Discussion
National Weather Service New York NY
505 AM EDT Fri Jun 6 2025

.SYNOPSIS...
A cold front slowly approaches the area today before passing through
on Saturday afternoon into evening. Weak high pressure then briefly
follows for Sunday followed by a series of weak lows passing to the
south and east Sunday night into Monday. A slow moving frontal system
will then work across the area Tuesday into early Wednesday. High
pressure returns later in the day Wednesday and remains near the
region through Friday.

&&

.NEAR TERM /THROUGH TONIGHT/...
A surface trough lingers over or nearby the far NW portion of the
forecast area today. Meanwhile, shortwave lift approaches from the
west and passes through this afternoon into tonight. This forcing is
progged to be over the NW half of the area, and along with CAPES of
1000-2000 J/kg, this is where the better chances of showers and
thunderstorms will be during this period. Thunderstorms could be
strong given the CAPE, but shear is weak, so the threat of severe
storms is limited. The weak shear will however promote slow-moving
storm cells. PWATs will be highest (near 2 inches) in the vicinity
of the surface trough where moisture convergence will be greatest,
and the mid level flow, while weak, will still be parallel to the
horizontal orientation of this moisture convergence. This will then
promote the chances of training for any of these relatively slow-
morning cells that may develop. The highest threat of flooding
impacts will therefore be over the far NW zones, where HREF 1 and 3-
hour rainfall exceedance probabilities are the highest, and where WPC
maintains a marginal risk of flash flooding. Any flooding will more
likely be minor, but cannot rule out isolated flash flooding here.
Also can`t rule out minor/poor drainage flooding for the rest of the
Lower Hudson Valley and adjacent areas.

The rain threat then lowers late evening, but begins to increase
late at night, particularly for the NW portions where the surface
boundary remains and another shortwave approaches. CAPEs will be
much lower by this time, so left out thunder for the late night
hours. Otherwise, low temps above normal across the area and
probably at least some patchy fog overnight for parts of LI and CT
with a continued light onshore flow.

&&

.SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
A pre-frontal trough and shortwave pass through during Saturday
morning, followed by a cold front during the afternoon and evening.
Showers likely for all but eastern LI and SE CT, but even here
chances are still 30-50%. Instability will be lower this time, but
thunderstorms remain possible. Severe storms not anticipated with
lower CAPE and shear remaining weak. Flooding impacts not
anticipated either with less training potential and faster forward
motion as compared to today. There should be less in the way of
clouds during the afternoon, and high temperatures probably end up a
few degrees above normal in most cases.

High pressure builds in behind the departing cold front after
Saturday evening. This likely keeps us dry through the daytime on
Sunday, but still can`t rule out some light rain in the afternoon,
mainly from around the city to points west. Rain chances then
increase at night as a broad area of low pressure approaches from the
south and west. Have PoPs capped at 50% for the time being, but
based on trends over the past day, might need to bump up chances
with subsequent updates. Highs for Sunday near normal in spite of an
abundance of mid to high level clouds.

&&

.LONG TERM /MONDAY THROUGH THURSDAY/...
Stayed close to the NBM/previous forecast However, there continues
to be some timing and placement issues with some weather features
towards the beginning of the long term period.

The long term period starts off with a broad upper level trough over
the area with a series of weak lows expected to pass near the region
Monday into Tuesday. There is some uncertainty with the location of
a weak surface low passing to the south Sunday night into Monday
morning. Like its previous run, the 00Z GFS is far enough to the
south to keep the area dry. Meanwhile the ECMWF is far enough north
to bring some rainfall to the region, however not as wet as the 12z
run yesterday. The NBM for now has around a 20 POP for Monday
morning, with some drier conditions for Monday afternoon.

POPs increase again Monday night into Tuesday as a frontal system
works into the area. The best chances for rain at this time looks to
be Tuesday afternoon/evening. Will continue to carry a chance of
thunder, however, instability looks to be marginal at this time. The
cold front pushes across the region late Tuesday night into early
Wednesday morning. High pressure then builds in behind the front.
Can not rule out a few isolated showers Wednesday afternoon as the
upper low is a bit slower to depart. Dry weather then follows for
Thursday and Friday.

With cloud cover and rain chances, expect temperatures to remain in
the lower to middle 70s Monday and Tuesday. Temperatures then
gradually warm Wednesday through Friday, with temperatures in the
upper 70s and 80s.

&&

.AVIATION /09Z FRIDAY THROUGH TUESDAY/...
A cold front slowly approaches from the west through the TAF
period.

Mainly VFR through the TAF period. There is a chance for MVFR/IFR at
KGON and potentially KISP early this morning. There is also a chance
for showers and thunderstorms and MVFR conditions this afternoon and
evening, mainly from the NYC metro on NW. Additional MVFR cigs/vsbys
possible once again tonight into Saturday morning.

SW winds will remain less than 10 kt with most terminals becoming
light and/or variable early this morning. Winds should settle to the
SW-S by midday and remain there through the afternoon. Speeds will
be around 10 kt for most sites, but could be a few kt higher at
times near the coast. Light winds return for tonight.

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

Some wind direction variability is expected this morning, mainly
before 15z.

Amendments possible for timing of shower/thunderstorm potential
this evening.

.OUTLOOK FOR 06Z SATURDAY THROUGH TUESDAY...

Friday night: Pockets of MVFR/IFR possible. Chance of a shower or
thunderstorm, mainly NW of the NYC metro.

Saturday: MVFR/IFR and showers possible. Slight chance of a
thunderstorm.

Sunday: VFR daytime. Chance of MVFR and showers at night.

Monday: VFR. Slight chance of a shower.

Tuesday: MVFR or lower possible. Showers likely with a chance of
thunderstorms in the afternoon and evening.

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

&&

.MARINE...
Winds and waves are expected to remain below SCA levels on all
waters through at least Saturday morning. Waves may reach 5 feet on
the ocean starting midday Saturday. With it being a late 3rd period
start, have decided to hold off on a SCA to see if models trend
lower with wave height forecasts. 5 ft seas could potentially
linger into Saturday night.

Thereafter, expect sub-advisory conditions through Tuesday. Waves of
low pressure passing to the south and a southerly swell will
keep seas on the ocean 3 to 4 ft. Chances increase for marginal
SCA conditions for seas around 5 ft Tuesday night into
Wednesday. Seas should then fall below SCA conditions on
Thursday.

&&

.HYDROLOGY...
Rain amounts of a half inch to inch are expected today through
Saturday afternoon, but mainly from around the city to points north
and west. The higher amounts will more likely occur over the Lower
Hudson Valley, and amounts higher than an inch are possible here.
See the near term section above for potential impacts.

No widespread hydrologic impacts otherwise for Saturday night through
Monday.

Showers and thunderstorms Tuesday into Tuesday night may produce at
least minor nuisance flooding. Low confidence at this time regarding
potential impacts this far ahead in time.

&&

.TIDES/COASTAL FLOODING...
There is a moderate rip current risk today for the Atlantic
beaches, but a building SE swell with waves around 5 feet will
result in a high risk for Saturday.

&&

.OKX WATCHES/WARNINGS/ADVISORIES...
CT...None.
NY...None.
NJ...None.
MARINE...None.

&&

$$

SYNOPSIS...BC/JC
NEAR TERM...JC
SHORT TERM...JC
LONG TERM...BC
AVIATION...JC
MARINE...BC/JC
HYDROLOGY...BC/JC
TIDES/COASTAL FLOODING...