811
FXUS61 KBOX 190707
AFDBOX

Area Forecast Discussion
National Weather Service Boston/Norton MA
207 AM EST Wed Nov 19 2025

.SYNOPSIS...
High pressure builds overhead for today and Thursday, bringing
relatively light winds and continued seasonable temperatures. A cold
front will bring a period of unsettled weather Friday, which may
linger into Saturday, then high pressure returns Sunday into early
next week.

&&

.NEAR TERM /THROUGH TONIGHT/...
Key Messages:

* Cool, dry, and less windy today.

Today:

A wave of low pressure will pass just to the south of SNE today,
while high pressure is over southern New England.  Mid-level dry air
will keep rain to our south, except for Nantucket, which may see a
few light showers this morning.  Skies across the south coast will
likely remain overcast much of the day, while northern Mass should
stay mostly sunny.  Weak warm-air advection will allow highs to
reach the mid to upper 40s.

Tonight:

High pressure remains parked over northern New England.  Winds flip
more northerly overnight, but remain light.  High-level clouds do
filter late over night as a weak piece of shortwave energy traverses
the zonal flow.  Should still see fairly good radiational cooling,
with temps falling into the upper teens to mid 20s away from the
coasts and urban areas.

&&

.SHORT TERM /THURSDAY THROUGH THURSDAY NIGHT/...
Key Messages:

* Dry weather and below normal temperatures.

No weather concerns heading into Thursday. 1025mb high pressure is
over New England for most of the day and then moving towards the
Canadian Maritimes overnight. Mixture of sun and clouds during the
day, giving way to more clouds late day into the overnight due to
WAA at 850mb. Otherwise a dry period with below normal temperatures.
Highs in the 40s and lows in the 20s, coastal locations hover around
freezing. Winds remain light and from the ENE.

&&

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

* No impactful weather expected Friday through early next week. A
  chance for showers late Friday into early Saturday, otherwise a
  mainly dry period of weather.

Deterministic models and ensemble members continue to have agreement
with a northern stream shortwave moving across northern New England
Friday evening. Thus, expect the daylight hours remains dry, with a
better chance for showers overnight into early Saturday. Where there
is disagreement is among how much moisture is available. GFS is the
most robust, with PWATs above 1.0" while ECMWF, NAM, and Canadian
favor less in the way of moisture. Generally less than 0.5" for the
areas away from the south coast of CT, RI, and MA. Do think the GFS
is more robust is due to a weak low pressure system development over
southern New England during this time frame. This scenario remains
an outlier. Nevertheless, this is a weakly forced environment and do
not expect any impacts. FWIW, DESI probabilities for 0.10" are best
south of I-90 between 30 to 50 percent. A southwest flow leads to a
warmer, albeit seasonable day, temperatures on Friday reach low-50s
for the coastal plain and upper-40s across the high terrain. A cold
front swings through on Saturday, 850mb temperatures at 12z are +5C
to +7C at 12z and by 00z temperatures drop -2C to 0C. Any lingering
moisture could result in a few flurries on Saturday. Highs are in
the 30s for the high terrain and 40s for the coastal plain.

Area of high pressure builds across the eastern seaboard Sunday into
early next week. The 500mb pattern is quasi-zonal, a weak shortwave
does pass through on Sunday, but given the dry atmosphere, think it
adds more clouds than anything to the forecast, otherwise a dry day.
Monday and Tuesday there is subtle mid-level ridging and continued
surface high pressure, dry conditions remain during this period. As
for temperatures highs are generally in the upper-40s to lower-50s
and nighttime lows in the 30s.

&&

.AVIATION /07Z WEDNESDAY THROUGH SUNDAY/...
Forecaster Confidence Levels...

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

Rest of Tonight... High Confidence.

VFR. Light westerly winds under 10 knots

Today and Tonight...High Confidence.

VFR. West winds turning NW less than 10 knots. Showers possible at
ACK Wed morning, otherwise dry for the rest of the region.

Thursday... High Confidence.

VFR. Variable wind direction across much of the region with speeds
less than 5 knots. Across eastern MA and RI, wind direction are from
the NE with speeds less than 8 knots.

KBOS Terminal...High confidence in TAF.

VFR. W winds turning NW around 10 knots.

KBDL Terminal...High confidence in TAF.

VFR. Light NW winds around 5 knots.

Outlook /Friday through Sunday/...

Friday through Friday Night: Mainly VFR, with local MVFR
possible. Slight chance RA.

Saturday through Sunday: VFR. Slight chance RA.

&&

.MARINE...
Forecaster Confidence Levels...

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

Today through Thursday... High Confidence.

Weak low pressure system passes south of the waters today, bringing
shower activity to the southern outer waters. High pressure returns
tonight into Thursday with tranquil conditions.

Seas today and Thursday are less than 3 feet. Light NW to NNW wind
with gusts less than 15 knots today. Wind becomes calm overnight and
then going NNE to NE Thursday with gusts less than 10 knots.

Outlook /Friday through Sunday/...

Friday: Winds less than 25 kt. Slight chance of rain.

Friday Night: Winds less than 25 kt. Seas locally approaching
5 ft. Chance of rain.

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

Saturday Night through Sunday: Winds less than 25 kt. Slight
chance of rain.

&&

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

&&

$$

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