Groton, Connecticut 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

396
FXUS61 KOKX 252029
AFDOKX

Area Forecast Discussion
National Weather Service New York NY
429 PM EDT Wed Jun 25 2025

.SYNOPSIS...
A cold front will move through from the north and east tonight,
then remain to the south through Thursday night. The front will
return north as a warm front and stall nearby Friday night
through Sunday night, then eventually lift north early next week
with a passing low in Canada. This low will drag a cold front
through late Tuesday into Tuesday night.

&&

.NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
Heat advisory remains in effect through 7 PM. Newark and JFK
both surpassed 100 degrees as expected, and heat index values
also over-peformed, with 105+ values in spots across NYC metro
and Long Island.

This will be the last day of the heat wave as a confluent upper
flow across eastern Canada and into the Northeast allows high
pressure to build to the north. This will allow a cold front to sag
south and west across the area tonight. Isolated to widely sct
showers/tstms possible late today into this evening. In
addition, a few showers/tstms possible along the eastern flank
of the cold front which backs in from the NE this evening.
Instability will be greatest across the Lower Hudson Valley and
interior NE NJ, and any storms that manage to develop could
have gusty winds given dry sub-cloud air and relatively dry mid
levels.

Chance for showers and isolated tstms will continue overnight as
weak impulses ride long the frontal boundary from the west and
weak warm advection continues as cooler maritime air undercuts
the warmer westerlies aloft. Brief downpours will be possible
late tonight, especially across NYC metro area, Long Island, and
the lower Hudson Valley. Meanwhile, the low levels will continue
to stabilize overnight in a NE-E flow. It will be noticeably
cooler tonight, but still several degrees above normal, with
lows mostly in the upper 60s/lower 70s.

&&

.SHORT TERM /6 AM THURSDAY MORNING THROUGH THURSDAY NIGHT/...
Following consistent 00Z/12Z HREF signaling potential for a band
of locally heavy showers and isolated tstms in the morning,
mainly across NE NJ, the NYC metro area and western Long Island.

Thereafter, convective complexes working in from the west will
likely dissipate, with the better chances for showers and
possible tstms north and west of NYC. Rainfall amounts will
generally be on the light side.

High temps on Thu will be in the lower 80s from NYC west, and
in the 70s across Long Island and S CT. Continued cool advection
Thu night will lead to a downright chilly night compared to
recent ones during the heat wave, with lows in the upper 50s and
lower 60s.

&&

.LONG TERM /FRIDAY THROUGH WEDNESDAY/...
Key Messages:

* Wet, unsettled weather late Friday into Saturday night.

* Mostly dry Sunday into Monday.

* Low confidence temperature forecast Saturday through Monday.

* Warm & wet Monday Night into Tuesday.

A stalled frontal boundary draped over the Mid-Atlantic states
Friday morning pushes back northward Friday afternoon into
Friday night. This warm front is then expected to stall nearby
Friday night through the weekend. Simultaneously, weakly
amplified mid-level shortwave passes to our north late Friday
into Saturday night within mainly zonal flow. Weakly amplified
ridging aloft may return on Sunday into Monday.

Given the nearby frontal boundary and the passing shortwave
bringing pockets of midlevel energy through the area,
unsettled weather is anticipated to start late Friday and linger
into Saturday night. While not a total washout, periodic
passing showers are expected. This is aided by PWATs of 1.75 to
2.25" through this period.

Thunderstorm chances and temperatures are harder to pinpoint
Friday night into the weekend. It is all dependent on if the
warm front will pass north of our area before stalling nearby or
stall south of our area. Among the available guidance, the
timing and location of the warm frontal passage varies, with
some bringing it through Friday night and others not bringing it
through until Sunday night or Monday. Should it stall south,
easterly flow would lead to cooler temperatures & showers Friday
afternoon into Saturday night. Should it advance north,
southerly flow would lead to warmer temperatures & dewpoints,
better aiding in not only shower coverage, but also a better
environment for thunderstorm development.

Nothing paints this uncertainty better than looking at the NBM`s
25th and 75th percentiles for temperatures which vary by more
than 10-15 degrees Saturday through Monday. Meaning highs could
end up in the upper-70s/lower-80s or the upper-80s/lower-90s on
these days, solely depending on the stalled front`s location.

Regardless, confidence in mostly dry weather Sunday into Monday
is more confident given weak ridging aloft anticipated by most
guidance.

An occluded low in Canada should capture the warm front on
Monday, dragging it northward. This will leave us warm-
sectored with a period of wet, unsettled weather Monday night
into Tuesday. A cold front Tuesday night should lead to cooling
temperatures and drier weather by Wednesday.

Temperatures and POPs in the long-term forecast were driven
mostly by NBM due to low confidence.

&&

.AVIATION /20Z WEDNESDAY THROUGH MONDAY/...
High pressure remains in control this afternoon. A cold front
then moves through the terminals late this evening, slowly
pushing south through Thursday.

Mainly VFR.

NW winds around 10 kt this afternoon. Winds veer N-NE late this
evening, then more NE-E for Thursday.

Isolated showers or thunderstorms cannot be ruled out into this
evening, but not enough probability and coverage to include in
TAFs at this time. Better chance toward the Thursday morning
push, so have included PROB30 for this potential.

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

Occasional gusts 15-19kt possible until around 22Z. Only
moderate confidence that sea breeze crosses KJFK. The sea
breeze may pass through, then thereafter shift back south
through the terminal and cause winds to shift back W to NW late
this afternoon/early evening.

.OUTLOOK FOR 18Z THURSDAY THROUGH MONDAY...

Thursday PM: VFR.

Friday through Sunday: MVFR or lower possible. Chance of
showers.

Monday: Mainly VFR.

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

&&

.MARINE...
A strengthening E flow on the ocean waters will lead to gusts
up to 20 kt and seas up to 4 ft daytime Thu. SCA cond then
expected on the ocean waters Thu night into Fri, with seas
building to 5-6 ft and gusts up to 25 kt.

&&

.HYDROLOGY...
Localized downpours of 1-1.5 inches may be possible somewhere
across NE NJ over to the NYC metro area and western Long Island
Thu morning, leading to localized instances of urban and poor
drainage flooding, with a marginal risk of flash flooding.

&&

.TIDES/COASTAL FLOODING...
Persistent E flow after a cold frontal passage should lead to
widespread minor coastal flooding in NY Harbor, the back bays of
S Queens/Nassau, Peconic Bay, and the Westchester/SW CT
coastline with the Thu night high tide cycle.

There is a moderate rip current on Thursday due to a building E
swell and 2-ft breakers in the surf zone.

&&

.CLIMATE...
Today`s Daily Record High Temperatures:
EWR  100 / 2025 (ties 1943)
BDR   95 / 2025 (was 94 / 1952)
NYC   99 / 1943, 1952
LGA   99 / 2025 (ties 1943, 1952)
JFK  102 / 2025 (was 98 / 1952)
ISP   95 / 2025 (was 92 / 2003)

&&

.OKX WATCHES/WARNINGS/ADVISORIES...
CT...Heat Advisory until 7 PM EDT this evening for CTZ005>012.
     Air Quality Alert until 11 PM EDT this evening for CTZ009>012.
NY...Heat Advisory until 7 PM EDT this evening for NYZ067>075-
     078>081-176>179.
     Air Quality Alert until 11 PM EDT this evening for NYZ069>075-
     078>081-176>179.
NJ...Heat Advisory until 7 PM EDT this evening for NJZ002-004-006-
     103>108.
     Air Quality Alert until 11 PM EDT this evening for NJZ004-006-
     103>108.
MARINE...None.

&&

$$

SYNOPSIS...BG/BR
NEAR TERM...BG
SHORT TERM...BG
LONG TERM...BR
AVIATION...JC
MARINE...BG/BR
HYDROLOGY...BG/BR
TIDES/COASTAL FLOODING...BG
CLIMATE...BG