777
FXUS61 KBOX 211135
AFDBOX

Area Forecast Discussion
National Weather Service Boston/Norton MA
735 AM EDT Fri Aug 21 2026

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

&&

.KEY MESSAGES...

- Cooler than normal temperatures today with steady rain most
  likely towards eastern MA.

- Wet and unusually cool for the weekend.

- Drier and warmer to start next week.

&&

.DISCUSSION...
KEY MESSAGE 1...Cooler than normal temperatures today with steady
rain most likely towards eastern MA.

Weak low pressure currently centered south of Long Island is
expected to slowly shift northeastward today. As it does, eastern
MA, particularly in SE MA, Cape Cod, and the Islands, will likely
see a continuation of steadier rain. There remains a consistent
sharp gradient that starts in the northern portion of the south
shore, continues along I-95 to the RI border, then along the
northern borders of RI and CT where expected rainfall totals drop
from around 0.5" to around 0.3" to the NW, diminishing heading
further north. The NAM once again appears to be an outlier with
regards to totals, as the other models trend more towards an
additional 0.1" or less towards Boston and north and west, then up
to an additional 0.25"-0.5" towards the Cape, SE MA, and RI. The
latest HREF PMM has also kept the footprint of higher totals to SE
MA, Cape Cod, the Islands, RI, and along the south coast. With
persistent cloud cover and resultant surface cyclonic flow from the
low pressure, onshore winds will keep the region feeling much cooler
than normal for late August. Highs today will likely only get to the
low to mid 70s in the eastern part of the region, with coastal areas
possibly being cooler. Towards the interior, not much in the way of
additional precipitation is expected, though cloudier conditions are
still expected given this pattern. Temperatures there may get into
the upper 70s, particularly in the CT River Valley.

Rain should become much lighter going into tonight. Onshore winds
continue, though may start pivoting more northerly as the low
continues northeastward. Lows will generally be in the 50s for much
of the interior and the 60s further east.

KEY MESSAGE 2...Wet and unusually cool for the weekend.

The low pressure to our south will continue tracking NE heading into
Saturday. The cold front associated with it will likely stall and
linger over and around our eastern coastline, possibly crossing
right through the Cape. With the front just staying put, the more
overcast and onshore flow would persist into Saturday. Slight
discrepancies still exist within the model guidance regarding the
low`s exact location, but the general consensus is that it should be
just offshore of Nantucket sometime Saturday morning. The NAM has
this low tracking further to the northeast at a faster pace than the
other models, while the Canadian and the RAP have it tracking much
slower, still sitting just south of Long Island by that same time.
As the day goes on, the low is expected to track more north and
could reach downeast Maine by Saturday night.

The synoptic story for the weekend remains generally unchanged; a
much more amplified trough with strong cyclonic flow overhead moves
closer from the Great Lakes Saturday into Sunday. This set up in
conjunction with an anomalous moisture plume containing PWATs
approaching 2.0" favors more widespread rainfall across the region
for the weekend. NAEFS guidance indicates specific humidity and PWAT
values up to around 2 standard deviations above normal associated
with this plume, and other guidance shows favorable IVT right over
much of eastern MA and RI within the same timeframe this weekend.
Ensembles do have low probs for 1" totals in 24 hours ending Sunday,
notably towards the Cape and Islands between the ECMWF ensemble and
the Canadian ensemble. Totals reaching the 1" to 1.5" mark are not
out of the question.

Temperatures this weekend will likely continue to be below normal
for this time of year, given the onshore flow and persistent cloud
cover. Highs will likely top out in the 70s both days, with Saturday
looking to be the slightly cooler day of the two as Sunday starts to
see some drier air move in during the day, helping reduce cloud
cover. Given the continued onshore flow and the cooler temperatures,
not much in the way of instability is expected to develop. Some
embedded thunder can`t be entirely ruled out, but predominantly
stratiform rain is expected.

KEY MESSAGE 3...Drier and warmer to start next week.

The front finally shifts offshore as the trough aloft progresses
east and the surface low exits the east coast area. Post-front, much
drier air takes hold with more westerly winds, clearing out
clouds and dropping dewpoints through Wednesday. The base of the
trough tracks directly overhead into Tuesday and heights rise
behind it as it continues eastward. High pressure dominates and
high temperatures return to the 70s and 80s.

&&

.AVIATION /12Z FRIDAY THROUGH TUESDAY/...
Forecaster Confidence Levels...

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

12z TAF Update:

Today and Tonight: Moderate confidence.

Mainly MVFR with IFR intervals over PVD and Cape Cod/Islands
with 4-6 SM -SHRA. Elsewhere SCT-OVC VFR ceilings should generally
govern, with overcast bases furthest east and south one goes.
Off-and-on periods of very light rain or drizzle for ORH, BOS
and BED. NE winds 5-10 kt, strongest eastern coastal airports.

Tonight: Moderate confidence.

Categories should deteriorate down to MVFR-IFR levels northward
to BOS, BED and ORH, while continuing at MVFR-IFR levels for
the Cape airports. BDL should remain SCT VFR. Best chance for
light -SHRA mainly eastern airports. N to NE winds 5-10 kt.

Saturday...Moderate confidence.

MVFR-IFR as yet another round of rain may impact the area. Exact
timing uncertain during the daytime hours and it should be
lighter before picking up in the afternoon/evening. This timing
is subject to change with future updates. Continued cyclonic
flow will keep winds generally NE to NNE up to 10 kt,
occasionally reaching 15 kt in E MA.

KBOS Terminal...Moderate confidence in TAF. Mainly OVC VFR
ceilings today with NE winds around 10 kt, with off-and-on -SHRA
or drizzle. Categories more likely to deteriorate to sub-VFR
late today and especially tonight.

KBDL Terminal...High confidence in TAF. Stronger confidence in
prevailing VFR and relatively drier weather.

Outlook /Saturday Night through Tuesday/...

Saturday Night: MVFR/IFR conditions possible. Chance SHRA.

Sunday: Mainly VFR, with areas IFR possible. Chance SHRA,
isolated TSRA.

Sunday Night: VFR. Slight chance SHRA.

Monday: VFR. Breezy.

Monday Night: VFR.

Tuesday: VFR. Breezy.

&&

.MARINE...
Forecaster Confidence Levels...

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

Through Saturday...High confidence.

Winds and seas should remain below SCA criterion through
Friday night. Winds shift more NE today and may get up to
around 20 kt over the southern waters. Elsewhere, winds
generally range between 10-15 kt. Winds diminish slightly and
turn more N Friday night into Saturday morning. Winds over the
eastern waters maintain more of an easterly component to them,
ranging from NE to SE. The southern waters shift more W, ranging
between NW and SW by Saturday afternoon. Seas mainly 3 ft or
less for all waters with localized spots of 4 ft seas Saturday.

Main issue for mariners is reduced visibilities in rain and
mist Friday night, especially for the eastern waters.

Outlook /Saturday Night through Tuesday/...

Saturday Night: Winds less than 25 kt. Rain showers likely,
isolated thunderstorms.

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

Sunday Night: Winds less than 25 kt. Local rough seas. Chance
of rain showers, slight chance of thunderstorms.

Monday through Monday Night: Winds less than 25 kt. Seas up to
5 ft.

Tuesday: Winds less than 25 kt.

&&

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

&&

$$

DISCUSSION...Hrencecin
AVIATION...Loconto/Hrencecin
MARINE...Hrencecin