145
FXUS61 KBOX 280654
AFDBOX

Area Forecast Discussion
National Weather Service Boston/Norton MA
254 AM EDT Thu Aug 28 2025

.SYNOPSIS...
Dry weather returns today, with modest southerly winds. A cold
front should bring another round of showers and thunderstorms
on Friday, with thunderstorms more likely across central and
eastern portions of Southern New England. A dry weather pattern
should prevail over the weekend and into next week, along with
a gradual warming trend.

&&

.NEAR TERM /THROUGH TONIGHT/...
230 AM Update:

Key Messages:

* Filtered sun today through high clouds with modest southerly
  breezes. Highs in the 70s, with cooler seabreezes for eastern MA.

* Quite a bit milder tonight, with spotty rain showers developing
  toward daybreak. Lows in the upper 50s to lower 60s, some 10
  degrees warmer than previous nights.

Details:

Lead shortwave disturbance at 500 mb, responsible for yesterday`s
scattered showers and small-hail-producing t-storms, is now offshore
as of early this morning. Weak shortwave ridging is now building in
with sfc high pressure in control. Water vapor satellite imagery
shows the next reinforcing mid-level trough now over Hudson Bay,
with axis extending through the Gt Lakes region. This feature and
its associated sfc cold front will play a larger role in the weather
for tonight and especially into Fri.

For today though, an area of high clouds over the OH Valley is
expected to stream N/NE during the morning to early afternoon hours.
These clouds won`t amount to much more than a filtered-sun look for
today though, with dry weather the rule. A gradually increasing SWly
pressure gradient through the day will allow for SW winds to perk up
some, to around 5-10 mph with some occasional gusts to no more than
20 mph. These SWlys cast some question as to how long a seabreeze on
the eastern MA coast can develop and/or be sustained; it most likely
ends up being fairly brief, except for those along the North
Shore/Cape Ann. But other than that though, a return to quiet
weather with thermal advection turning to weak warm advection but
the high cloud canopy should keep temps closer to the mid/upper 70s
for most. Coastal seabreezes along the North Shore and along the
immediate south coast/Cape Cod should lead to slightly cooler temps
in the lower 70s.

For tonight...we enter into a warm-sector airmass, with accompanying
rising dewpoints and increased cloud cover (especially toward
daybreak). When combined with southerly winds around 5-10 mph during
the evening and overnight, this is a setup which favors a slow fall
in temps and have added a few degrees to NBM lows to account for
this. It looks as though cold-frontal showers should hold off into
western New England until daybreak Friday. However there are some
hints at warm-advection rain showers in some of the 00z NWP output
along the south coast and southern coastal waters, and even into
parts of the I-95 corridor. So started to introduce a slight chance
PoP for showers between 08-12z. Regardless, tonight will be quite a
bit warmer with a little bit more humidity too but I`d hesitate to
call it "muggy" with dewpoints in the upper 50s/around 60. Lows
tonight in the upper 50s to lower 60s.

&&

.SHORT TERM /FRIDAY THROUGH FRIDAY NIGHT/...
230 AM Update:

Key Messages:

* Scattered showers and thunderstorms on Fri, with better chances
  for thunderstorms from central MA/eastern CT into RI/eastern MA
  during the early to midafternoon. Severe weather isn`t expected,
  but a couple storms may produce briefly strong wind gusts and
  small (sub-severe) hail. Highs in the 70s.

* Clearing/drying Fri night, lows in the 50s.

Details:

Sfc cold front or frontal occlusion will be moving eastward
from eastern NY through the New England states on Fri. While
there might be some showers ongoing by daybreak, pretty good
frontal convergence as sfc winds back to SE ahead of the front
fosters showers and thunderstorms to develop in greater numbers.
The biggest question mark is the timing of the front`s progress
through Southern New England; while a few solutions are slower,
a rough consensus seems to be during the mid morning into the
Berkshires and to the eastern coastal waters by mid/late
afternoon. Thinking it`s more likely that areas east of I-91
have the better chance at seeing some weak destabilization and
some thunderstorms. Similar to yesterday, wet bulb zero heights
are quite low at around 7000-8000 ft AGL. Even still, CAPE
values are less than 1000 J/kg in all areas, and while there is
some speed shear, shear magnitudes of around 30 to 35 kts are
not suggestive of severe weather potential. A couple storms
could become strong and capable of briefly strong gusts and
small hail, mainly from central MA, eastern CT, RI and eastern
MA/North Shore area, but severe weather potential looks very low
to nil. PoPs in the Likely range, which decrease from west to
east late in the day. Partly cloudy with highs in the mid 70s.

Cold front then moves offshore with some residual showers or t-
storms for the Cape and Islands early tonight. We then start to
become governed by troughing associated with a closed upper low
which is forecast to meander around northern New England.
Cooler air filters in on modest northwest winds post-frontal,
along with falling dewpoints. We should see mostly clear skies,
but may trend partly cloudy in NW MA closer to the upper low and
its associated cold pocket and related moisture. Lows upper 40s
to the mid 50s, with mid/upper 50s over Cape Cod and the
Islands.

&&

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

* Extended stretch of tranquil/dry weather this weekend into the
  middle of next week, with seasonable days and cool nights.

* Next chance for rain may hold off until late next week.

Details:

Entering into an extended stretch of dry weather in this
period, as a broad area of surface high pressure moves in from
the Gt Lakes this weekend and then parks itself over Nova
Scotia/Canadian Maritimes into the middle of next week.
Initially we`re under deep cyclonic flow aloft from a closed
upper low over northern New England; aside from diurnally driven
cumulus clouds, no impacts to sensible weather are expected
with the main threat for showers being in far northern New
England. While the 500 mb pattern becomes more complex/blocky as
we move into early next week, it doesn`t look like rain will be
in the offing for quite some time, potentially not until late
next week.

Temperatures start off a little cooler than normal, then a
modest warm up as we move into the early to middle part of the
workweek. Expect strong diurnal ranges to high and low temps
(mild days, cool nights). All told, pretty nice weather to close
out August and flip the calendar to September.

&&

.AVIATION /07Z THURSDAY THROUGH MONDAY/...
Forecaster Confidence Levels...

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

00z TAF Update: High confidence.

Through 12z Thursday: High confidence.

Mainly VFR, though BAF/BDL and BED could see fog develop around
08-09z. Light/calm winds.

Today: High confidence, though moderate on seabreeze
development.

VFR, SCT-BKN high clouds. Light winds become S/SW around 10 kt
this aftn. Possible seabreeze 14-17z at BOS but would be brief
or stays just offshore.

Tonight: High confidence.

Mainly VFR, though some coastal fog/stratus could be possible
for the Cape as moisture levels rise. Possible SHRA 08-12z for
the south coast and the I-95 corridor, but this is still
uncertain. SW winds 5-10 kt.

Friday: Moderate confidence.

Mainly VFR, though some brief sub-VFR restrictions possible in
SHRA/TS as cold front moves through ~14-22z. Best chance for TS
mainly ORH eastward, a couple strong TS possible but severe not
expected. S to SE winds 5-10 kt before frontal passage, then
shifting to W/WNW late in the day after frontal passage.

KBOS TAF...High confidence in TAF, moderate on seabreeze. Brief
window for seabreeze between 14-17z (or possibly just offshore)
before SW winds pick up to around 10 kt thereafter.

KBDL TAF...High confidence in TAF.

Outlook /Saturday through Monday/...

VFR.

&&

.MARINE...
Forecaster Confidence Levels...

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

Overall high confidence.

Winds and seas remain below SCA through Fri.

South winds are expected today around 10-15 kt, increasing to
around 15-20 kt Fri. Possible fog tonight over the the south-
coastal waters. Potential for a few thunderstorms Fri into Fri
night over the waters, before a windshift to W Fri night.

Outlook /Saturday through Monday/...

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...Loconto
NEAR TERM...Loconto
SHORT TERM...Loconto
LONG TERM...Loconto
AVIATION...Loconto
MARINE...Loconto