864
FXUS61 KBOX 212255
AFDBOX

Area Forecast Discussion
National Weather Service Boston/Norton MA
555 PM EST Fri Nov 21 2025

.SYNOPSIS...
A weak wave of low pressure passes well to our south very late
tonight into Saturday morning, which will bring a brief round of
showers mainly across parts of Connecticut, Rhode Island and
southeast Massachusetts. Otherwise, dry and seasonably cool weather
is on tap for the weekend into Monday. Low pressure approaching from
the west will likely bring a period of rain later Tuesday and/or
Wednesday with drier weather favored by Thanksgiving.

&&

.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
Key Messages...

* Rather cloudy tonight with lows in the 30s to the lower 40s
* Some showers approach near daybreak...mainly across CT/RI/SE MA

Details...

Tonight...

High pressure off the mid-Atlantic coast will result in continued
warm advection tonight...resulting in rather cloudy skies. Shortwave
energy over the southern Great Lakes will move east across the mid-
Atlantic states tonight. Strong upper level energy over Quebec will
keep the mid level flow zonal and limit the northern extent of
the rain shield with this wave of low pressure. We do think some
showers will arrive near daybreak mainly across CT/RI/MA and
especially near the south coast. Some of the guidance takes a
few showers as far north as I-90...but if this occurs any
showers will be light/short-lived. Low temps should bottom out
in the 30s to the lower 40s.

&&

.SHORT TERM /6 AM SATURDAY MORNING THROUGH SATURDAY NIGHT/...
Key Messages...

* Lingering showers mainly across CT/RI/SE MA early Sat ends by
  lunchtime...followed by partial clearing & highs mainly upper 40s

* Clear & cold Sat night with lows mainly in the 20s

Details...

Saturday...

The northern edge of the showers mainly impacts portions of CT/RI/SE
MA Sat morning...but a few showers may briefly reach near I-90.
These showers will not last long and should exit the region by
lunchtime with any rainfall amounts rather light. This will be
followed by partial clearing Sat afternoon from northwest to
southeast. This partial clearing may not come in time for much
sunshine though towards the Cape and Islands with the early sunset
this time of year. High temps on Sat will mainly be in the upper 40s
with a few spots reaching near 50.

Saturday night...

A ridge of high pressure builds into the region from the west
Saturday night. This will result in mainly clear
skies...light/calm winds and an excellent night of radiational
cooling. Low temps should bottom out mainly in the 20s with some
of the normally coldest spots perhaps dipping into the upper
teens. The urban heat island of Boston will be the mild spot
with low temps bottom out in the lower 30s.

&&

.LONG TERM /SUNDAY THROUGH FRIDAY/...
Key Messages:

* Mostly dry and sunny through the weekend, but returning to
  unsettled conditions by mid-week.

Mostly dry and sunny for the remainder of the weekend as high
pressure builds and moves across southern New England. Afternoon
high temperatures expected in the mid to upper 40s (except mid to
upper 30s for higher terrain areas).

Next chance for rain showers comes mid-week as another low pressure
system passes through the James Bay and a high pressure moves
offshore. Model guidance remains uncertain... the ECMWF is
indicating a single round of showers pushing through Wednesday, but
the GFS and Canadian are showing a secondary round of showers moving
through Thursday morning. Regardless of differences in timing, there
appears to be quite a lot of consensus as to PWAT values ranging
from 0.8" in the northwest to 1.2" across the Cape and Islands.
Still expecting precip to remain as rain showers at this time as
surface temps remain above freezing, likely in the mid to upper 40s
Tuesday and Wednesday afternoons.

&&

.AVIATION /00Z SATURDAY THROUGH WEDNESDAY/...
Forecaster Confidence Levels...

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

00z TAF Update...

tonight...High confidence.

A broken to overcast deck of marginal MVFR-VFR ceilings will
persist tonight. The northern edge of the showers may approach
parts of CT/RI/SE MA near daybreak. Light SW winds.

Saturday...High confidence.

Some marginal MVFR conditions possible Saturday morning mainly
across CT/RI/SE MA on the northern edge of a shield of showers. The
best chance of these conditions are towards the south coast and any
of this activity should depart by lunchtime. Otherwise...VFR
conditions with winds becoming NW at 5-10 knots.

Saturday night...High confidence.

VFR. Calm/light NW winds.

KBOS Terminal...High confidence in TAF.

KBDL Terminal...High confidence in TAF.

Outlook /Sunday through Wednesday/...

Sunday: VFR.

Sunday Night through Monday: VFR. Breezy.

Monday Night: VFR.

Tuesday: VFR. Chance RA.

Tuesday Night: Mainly MVFR, with areas IFR possible. RA likely.

Wednesday: MVFR/IFR conditions possible. Breezy. Chance RA.

&&

.MARINE...
Forecaster Confidence Levels...

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

Tonight through Saturday night...High confidence.

Low pressure will pass well south of the waters later tonight into
Sat morning. This will be followed by a ridge of high pressure
building in from the west Sat night. We probably will see a period
of NW wind gusts of 20 to 25 knots late Sat/Sat evening in the cold
air advection pattern. While this may briefly reach marginal small
craft advisory thresholds...overall expect conditions to remain
below criteria through Sat night.

Outlook /Sunday through Wednesday/...

Sunday: Winds less than 25 kt.

Sunday Night through Monday: Winds less than 25 kt. Seas
locally approaching 5 ft.

Monday Night: Winds less than 25 kt.

Tuesday: Winds less than 25 kt. Chance of rain.

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

Wednesday: Winds less than 25 kt. Areas of seas approaching
5 ft. Rain likely.

&&

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

&&

$$

SYNOPSIS...Frank/McMinn
NEAR TERM...Frank
SHORT TERM...Frank
LONG TERM...McMinn
AVIATION...Frank/McMinn
MARINE...Frank/McMinn