109
FXUS61 KBOX 271743
AFDBOX

Area Forecast Discussion
National Weather Service Boston/Norton MA
143 PM EDT Wed Aug 27 2025

.SYNOPSIS...
Scattered showers or thunderstorms will come to an end early
this evening, followed by dry weather Thursday as high pressure
builds into the region. A cold front should bring another round
of showers and thunderstorms Friday. A dry weather pattern
should prevail over the weekend and into next week, along with a
gradual warming trend.

&&

.NEAR TERM /THROUGH TONIGHT/...
Updated 145 PM Wed

Key Message:

* Scattered showers/storms through early evening, some could
  produce small hail or briefly gusty winds.

Convection has begun to fire across southern New England this
afternoon, associated with upper trough moving through region.
Overall, parameters are less than impressive with weak
instability, but combined with sufficient large scale lift it`s
enough to produce scattered showers or even a few thunderstorms
through early this evening, as activity slowly shifts toward
coast.

Given colder air aloft, we could see small hail or even briefly
gusty winds (sub-severe) should some higher cores manage to
develop. This seems to be more likely to our north, in closer
proximity to upper cold pool, but many of the high-res models
show this potential across MA as well (especially NE MA).

Activity should diminish quickly toward sunset as we lose what
instability we have and upper trough heads offshore, resulting
in subsidence across region. Expecting skies to clear tonight
and we may see patchy fog in those locations that receive
rainfall.

&&

.SHORT TERM /THURSDAY THROUGH THURSDAY NIGHT/...
Updated 145 PM Wed

Key Message:

* High pressure brings dry weather.

Fairly quiet weather expected as upper ridging works into region
ahead of closed low digging into SE Canada. At surface, high
pressure briefly dominates and weak gradient will support
coastal sea breezes. This will be short lived, however, as an
approaching cold front brings increasing cloudiness Thu night
and perhaps a few showers toward daybreak Fri.

&&

.LONG TERM /FRIDAY THROUGH WEDNESDAY/...
Updated 145 PM Wed

Key Messages:

 * Scattered showers and thunderstorms Friday, timing still
   uncertain

 * Extended period of dry and pleasant weather starting Saturday
   through much of next week

An upper-level closed low and cold pool will stall over Northern New
England on Friday, sending some pieces of shortwave energy down into
Southern New England.  The timing of the shortwave energy is still
uncertain at this point and will likely be ahead of a cold front,
which will be the focus for thunderstorm activity.  Hi-res guidance
sources that extend through Friday indicate thunderstorms forming as
early as 8 am and as late as 1 pm across Southern New England.
Thunderstorms are unlikely to be severe on Friday, as shear will be
under 30 knots and instability appears limited, likely below 1000
J/kg.  The upper-level forcing may also be lacking should it move
through early in the day, ahead of the cold front.

Friday will likely be our last chance for any measurable
precipitation for the foreseeable future, as surface high pressure
parks itself over southern New England starting this weekend and
continuing into early next week.  High temperatures on Friday and
Saturday remain in the upper 60s to low 70s, with the cold pool
aloft and weak CAA behind the cold front.  The cold pool moves
offshore Sunday into Monday, allowing for a slight warming trend of
high temps in the upper 70s to low 80s through the middle of next
week.

&&

.AVIATION /17Z WEDNESDAY THROUGH SUNDAY/...
Forecaster Confidence Levels...

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

18z TAF Update: High confidence.

Scattered showers/thunder expected through early this evening
which may bring brief MVFR conditions. Most sites will have a
PROB30 for -SHRA since confidence in TS is fairly low, but more
likely across northern MA. It`s also possible we see some patchy
fog with MVFR/IFR late tonight, mainly in areas that receive
rainfall. Otherwise VFR through Thu night. W/NW winds become SW
Thu with coastal sea breezes.

KBOS TAF...High confidence. Weak sea breeze should quickly give
way to W winds 18-19z.

KBDL TAF...High confidence.

Outlook /Friday through Monday/...

Friday: Mainly VFR, with local MVFR possible. Breezy. Chance
SHRA, slight chance TSRA.

Friday Night: VFR. Chance SHRA.

Saturday through Sunday Night: VFR.

Labor Day:

&&

.MARINE...
Forecaster Confidence Levels...

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

Updated 145 PM Wed

High confidence through the weekend as winds and seas remain
below SCA.

Scattered showers or a thunderstorm are expected through early
evening, then high pressure builds over the waters Thu. A cold
front should bring another round of showers and thunderstorms
Fri, followed by a large area of high pressure which should
prevail into most of next week.

Outlook /Friday through Monday/...

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

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

Saturday: Winds less than 25 kt. Slight chance of rain showers.

Saturday Night through Labor Day: Winds less than 25 kt.

&&

.BOX WATCHES/WARNINGS/ADVISORIES...
CT...None.
MA...None.
RI...None.
MARINE...None.

&&

$$

SYNOPSIS...KP/JWD
NEAR TERM...JWD
SHORT TERM...JWD
LONG TERM...KP
AVIATION...JWD
MARINE...KP/JWD