836
FXUS61 KBOX 012025
AFDBOX

Area Forecast Discussion
National Weather Service Boston/Norton MA
425 PM EDT Tue Sep 1 2026

.WHAT HAS CHANGED...
Small Craft Advisory remains in effect for the southern waters
through at least tomorrow morning.

&&

.KEY MESSAGES...

- Scattered showers tapering off tonight. Mainly dry conditions
  Wednesday with scattered showers and storms arriving overnight
  into Thursday.

- Still unsettled Thursday with showers and thunderstorms, with a
  low chance that some storms could become strong.

- Mix of clouds and sun with diurnally driven spot showers
  Friday into the early part of Labor Day Weekend, but drier
  weather most of the time. Dry and seasonable Sunday and on the
  Monday holiday, with onshore breezes.

&&

.DISCUSSION...
KEY MESSAGE 1...Scattered showers tapering off tonight. Mainly
dry conditions Wednesday with scattered showers and storms
arriving overnight into Thursday.

Expect scattered showers for the remainder of the afternoon,
decreasing in coverage this evening as higher pressure builds in
from the west. Can`t rule out a few isolated showers overnight,
otherwise most locations remain dry.

High pressure remains in place Wednesday supporting mainly dry
conditions with temperatures in the upper 60s and low 70s. A surface
low pressure system tracks across Canada bringing a series of fronts
across the region later Wednesday through Thursday. A warm front
pushes into southern New England Wednesday night accompanied by
advection of a plume of above normal moisture. Precipitable water
values rise to 1-1.8" overnight. Lift provided by the jet positioned
to the west and warm front will support the return of showers and
perhaps some embedded storms. There is uncertainty regarding the
finer details such as timing and thunderstorm probabilities due
to spread across model guidance. Showers/storms more likely
arrive in west and central portions of southern New England 11
PM to 2 AM arriving in the I-95 corridor 09-12Z. There are
indications of marginal elevated instability that accompanies
the plume of richer moisture. This may support a few embedded
thunderstorms. This has been reflected across the simulated
reflectivity in the high-res guidance, some more aggressive than
others. This has led to lower confidence on how widespread
embedded storms/heavy downpours will be. Steering flow appears
strong enough to support quicker storm motion which would limit
the risk for flash flooding. If there are embedded storms and
downpours, can`t rule out the potential for poor drainage/urban
flooding in the more vulnerable spots.

KEY MESSAGE 2...Still unsettled Thursday with showers and thunderstorms,
with a low chance that some storms could become strong.

Carrying over from Wednesday night is a continued risk for showers
and thunderstorms into Thursday, as a stronger shortwave impulse
moves through. The main question mark is on if storms could become
strong in this timeframe. Although the airmass is plenty humid and
mid and upper level wind fields are seasonably strong, considerable
cloud cover could temper how much destabilization occurs. GFS-
based CAPE profiles show about 800-1600 J/kg of most-unstable
CAPE with moist-adiabatic mid-level lapse rates also tempering
instability. It`s still debatable if storms could become strong
but the chances seem low with more tempered instability favored.
Still, Thursday looks to be a washout with good chances for
rains during the daytime hours, with more substantial clearing
taking place Thursday evening.

KEY MESSAGE 3...Mix of clouds and sun with diurnally driven spot showers
Friday into the early part of Labor Day Weekend, but drier
weather most of the time. Dry and seasonable Sunday and on the
Monday holiday, with onshore breezes.

Still under cyclonic flow aloft for Friday into the early part of
Labor Day Weekend. This will keep weather pattern somewhat unsettled
with a mix of clouds and sun. Spot showers are possible Friday
and Saturday afternoon but drier weather prevails most of the
time. much of the time. Broad high pressure then works in from
the north Sunday into Labor Day, leading to onshore breezes, but
with partly sunny skies and dry conditions.


&&

.AVIATION /20Z TUESDAY THROUGH SUNDAY/...
Forecaster Confidence Levels...

Low - less than 30 percent.
Moderate - 30 to 60 percent.
High - greater than 60 percent.

18z TAF Update...

Through 00Z...Moderate confidence in trends, lower confidence in
timing.

Mixture of IFR and MVFR ceilings with periodic showers and isolated
TSRA. East-southeast winds of 10-15 kt are expected at coastal
terminals and 6-10 kt for interior terminals.

Tonight...Moderate confidence.

MVFR ceilings generally prevail along and east of I-95, while areas
farther inland remain IFR to LIFR. Localized fog possible. Onshore
easterly winds and chances for SHRA ending after 06z.

Wednesday...High confidence.

VFR after 15z, however, mid-level clouds remain throughout the day.
Easterly to east-southeasterly wind prevail.

Wednesday Night...High confidence in trends, moderate confidence in
timing.

Showers returning overnight with embedded thunder, ceilings lowering
to IFR/LIFR. Southeast winds.

KBOS Terminal...High confidence in trends, moderate confidence
in timing.

KBDL Terminal...High confidence in trends, moderate confidence
in timing.

Outlook /Wednesday Night through Sunday/...

Thursday: Mainly VFR, with local IFR possible. Breezy. SHRA
likely, chance TSRA.

Thursday Night: VFR. Chance SHRA.

Friday through Friday Night: VFR.

Saturday: VFR. Breezy. Slight chance SHRA.

Saturday Night through Sunday: VFR. Breezy.

&&

.MARINE...
Forecaster Confidence Levels...

Low - less than 30 percent.
Moderate - 30 to 60 percent.
High - greater than 60 percent.

Through Wednesday Night...High confidence.

Scattered showers across the water this afternoon and evening, a
few showers moderate at times. Low chance for an embedded
thunderstorm. Easterly flow less than 25 kts across the eastern
waters. There is potential for a period of SCA gusts (~25 kts)
this evening and overnight for the southern waters tonight with
seas 3-5 ft. A SCA is in effect for the southern waters through
Wednesday morning. It is possible this may need to be extended
if 5 ft seas linger across southern outer waters off Block
Island Wednesday.

Outlook /Wednesday Night through Sunday/...

Thursday: Winds less than 25 kt. Seas locally approaching 5 ft.
Rain showers likely, slight chance of thunderstorms.

Thursday Night: Winds less than 25 kt. Seas locally approaching
5 ft. Chance of rain showers, slight chance of thunderstorms.

Friday: Winds less than 25 kt.

Friday Night: Winds less than 25 kt. Seas locally approaching
5 ft.

Saturday: Winds less than 25 kt. Areas of seas approaching
5 ft.

Saturday Night: Low risk for Small Craft Advisory winds with
gusts up to 25 kt. Local rough seas.

Sunday: Low risk for Small Craft Advisory winds with gusts up
to 25 kt. Areas of rough seas.

&&

.BOX WATCHES/WARNINGS/ADVISORIES...
CT...None.
MA...None.
RI...None.
MARINE...Small Craft Advisory until 8 AM EDT Wednesday for ANZ235-237-
     255-256.

&&

$$

DISCUSSION...Loconto/Mensch
AVIATION...Dooley
MARINE...Loconto/Mensch