751
FXUS61 KBOX 151737
AFDBOX

Area Forecast Discussion
National Weather Service Boston/Norton MA
137 PM EDT Sat Aug 15 2026

.WHAT HAS CHANGED...
No significant changes to the forecast.

&&

.KEY MESSAGES...

- Very comfortable temperatures this weekend with mainly dry
  conditions. There is a moderate risk for rip currents as well
  this weekend.

- Rain returns late Sunday into Monday, followed by quieter
  weather through most of next week.

- Seasonably warm temperatures and moderate humidity return
  through the middle of next week, followed by increasing shower
  chances late in the week.

&&

.DISCUSSION...
KEY MESSAGE 1...Very comfortable temperatures this weekend with
mainly dry conditions.

Clear skies and light winds early this morning are supporting
effective radiational cooling. Lows fall into the 50s across the
cooler outlying locations, while urban centers remain near 60
degrees by sunrise. Given these conditions, areas of valley fog have
begun to develop and can be seen on satellite imagery using the
Nighttime Microphysics RGB, with fog gradually filling the valleys.
Any morning fog will erode with daytime heating and lift by mid-
morning.

Quiet weather is the theme for the weekend as high pressure
originating from northern Canada settles across the Northeast
through the first half of Sunday. However, there remains a very low
chance for an isolated shower from mid to late afternoon, mainly
across eastern Massachusetts, as a potent mid-level shortwave with
an associated cold pool of -18C brushes the eastern fringes of the
region. Given PWATs are quite low, between 0.6 and 0.8 inches, and a
notably dry airmass remains in place, the threat for a stray shower
is very low. Our thinking is that this robust shortwave will result
in more cloud cover than anything else across eastern areas.

Temperatures remain seasonable, with highs generally ranging from
the upper 70s to lower 80s. Another cool night is expected Saturday
night, with clear skies and light winds supporting effective
radiational cooling. Lows fall into the lower to middle 50s across
the cooler outlying locations, while urban centers remain near 60
degrees.

Despite the pleasant weather, a moderate risk for rip currents is
expected today and Sunday. Those heading to the beach should
remain aware of local conditions and check with lifeguards or
beach staff regarding rip current risks at their specific
location.

High pressure begins to shift offshore Sunday as a low pressure
system approaches from the Great Lakes. Increasing warm air
advection will bring increasing clouds through the afternoon, while
temperatures remain seasonable in the upper 70s and lower 80s.
Humidity will gradually increase as dew points rise into the lower
60s. Most, if not all, of the daylight hours remain dry, with the
next opportunity for rainfall arriving Sunday night into Monday.

KEY MESSAGE 2...Rain returns late Sunday into Monday, followed by
quieter weather through most of next week.

Confidence remains high that most, if not all, of the daylight hours
Sunday remain dry. Rainfall arrives late Sunday, with the steadiest
rain anticipated overnight through early Monday. We are now entering
the time range where high-resolution guidance can begin to better
resolve this period. While some guidance brings rain into western
Massachusetts and western Connecticut as early as late afternoon,
prior to sunset, ensemble guidance supports a later arrival, with
measurable rainfall generally arriving between 8 PM and midnight.

There is increasing certainty in the overall evolution of this
system, with one area of low pressure likely passing across northern
New England and a secondary low tracking south of New England across
the Mid-Atlantic. This evolution is also supported by the ECMWF EFI
and Shift of Tails for QPF, which highlight both of these regions.
With southern New England positioned between these two areas,
confidence in the highest rainfall totals occurring across the
region has diminished, lowering the threat for widespread flash
flooding.

However, PWATs increase to between 1.8 and 2.1 inches overnight into
Monday, supporting the potential for locally heavier downpours. A
Marginal Risk for Excessive Rainfall (level 1 of 4) remains in place
for much of New England Sunday night into Monday, primarily due to
the potential for localized flash flooding. Ensemble guidance
currently supports a general range of 0.25 to 0.50 inches across
southern New England, though localized higher amounts are possible,
especially beneath heavier downpours.

Given the expected cloud cover and showers, Monday will be cooler,
with highs generally ranging from the mid-70s to around 80 degrees.
It will also be fairly humid, with dew points remaining elevated and
resulting in rather sticky conditions.

KEY MESSAGE 3...Seasonably warm temperatures and moderate humidity
return through the middle of next week, followed by increasing
shower chances late in the week.

Drier air advects in from the northwest beginning Monday night into
Tuesday, leading to another dry stretch Tuesday through Wednesday,
and possibly into the first half of Thursday, as surface high
pressure builds back into the region. Temperatures remain
seasonable, with highs in the lower to middle 80s and tolerable
humidity as dew points remain in the lower to middle 60s. Ensemble
guidance continues to signal a transition toward more unsettled
weather late in the week, with shower chances returning and
temperatures potentially trending slightly below normal.

&&

.AVIATION /18Z SATURDAY THROUGH THURSDAY/...
Forecaster Confidence Levels...

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

18z TAF Update...

Today...High confidence.

VFR. NW winds 5 to 10 kt. Sea breeze kicks out around sunset.

Tonight...High confidence.

VFR outside some touch of very localized ground fog possible
near daybreak in typically most prone low-lying locations.
Calm-light NW winds.

Sunday...High confidence.

VFR. S-SW winds 7-12 kt...except for a period of localized sea
breezes on the very immediate eastern MA coast.

KBOS Terminal...High confidence in TAF.

KBDL Terminal...High confidence in TAF.

Outlook /Sunday Night through Thursday/...

Monday: Mainly VFR, with local IFR possible. Breezy. Chance
SHRA.

Monday Night through Wednesday: VFR.

Wednesday Night: VFR. Slight chance SHRA.

Thursday: VFR. Breezy. Chance SHRA, slight chance TSRA.

&&

.MARINE...
Forecaster Confidence Levels...

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

Through Sunday...High confidence.

Tranquil boating conditions are expected as high pressure traverses
the Northeast through the weekend. Unsettled conditions arrive late
Sunday into Monday with the passage of a low pressure system. Winds
from the north today become somewhat variable as surface high
pressure moves overhead. Nearshore sea breezes develop, with winds
generally 10 to 15 kt.

On Sunday, winds shift to the south and increase to less than 20 kt.
Sunday night into Monday, seas build to 4-6 ft with wind gusts up to
25 kt. These are marginal conditions for a Small Craft Advisory, but
one may need to be considered for Sunday night into Monday.

Outlook /Sunday Night through Thursday/...

Monday: Moderate risk for Small Craft Advisory winds with gusts
up to 30 kt. Seas up to 5 ft. Rain showers likely.

Monday Night: Winds less than 25 kt. Areas of seas approaching
5 ft. Slight chance of rain showers.

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

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

Wednesday: Winds less than 25 kt.

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

Thursday: Winds less than 25 kt. Seas locally approaching 5 ft.
Chance of rain showers.

&&

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

&&

$$

DISCUSSION...Dooley
AVIATION...McMinn
MARINE...Dooley