443
FXUS61 KBOX 201122
AFDBOX

Area Forecast Discussion
National Weather Service Boston/Norton MA
622 AM EST Thu Nov 20 2025

.SYNOPSIS...
Aside from some rain Friday evening into Saturday ahead of a cold
front, dry and seasonably cool weather will prevail through early
next week as high pressure dominates our weather.

&&

.NEAR TERM /THROUGH TONIGHT/...
High pressure remains over the region today, but weak upper-level
energy will bring more high-level cloudiness.  As a result, high
temperatures wont be quite as warm as yesterday, staying in the low
to mid-40s.  Winds start light northerly, but become light and
variable by the afternoon.

&&

.SHORT TERM /FRIDAY/...
Tonight: Skies begin to clear this evening as the weak shortwave
energy moves offshore. With light winds again overnight, low temps
will be able to dip into the low 20s again away from the coasts and
urban areas. Hi-res guidance indicate the potential for some patchy
radiation fog along the east coast with dewpoints rising slightly
into the low 20s. With temperatures below freezing, there is a low
chance for freezing fog/drizzle in areas where fog becomes dense. If
freezing fog does form, it will likely just impact elevated surfaces
as ground temps may still be above freezing.

Friday: High pressure begins to shift offshore while a weak southern
stream shortwave approaches from the SW. WAA will bring 850mb temps
from +2C to +6C on Friday, helping high temps approach the low 50s.
Skies start mostly sunny, but more high clouds filter in late in the
day as that shortwave nears. A bit more breezy on Friday with SW
winds at 10-15mph.

&&

.LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/...
Key Messages:

* Overall, no impactful weather conditions are expected Friday night
  through early next week.

* Chance for light rain Friday night into early Saturday, otherwise
  a mostly dry extended forecast.

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 and NAM
are more robust, PWATs 0.8" to 1.0", while ECMWF and Canadian favor
less in the way of moisture. Generally less than 0.6" for the areas
away from the south coast of CT, RI, and MA. Think the GFS is more
robust due to a weak low pressure development over the waters south
of southern New England. Nevertheless, the environment is a weakly
forced and do not expect any impacts. FWIW, DESI probabilities for
0.25" are best in areas south/east of Hartford, Worcester, to Boston
with probabilities between 25 and 45 percent. Southwest flow leads
to a seasonable Friday with temperatures reaching the low-50s for
the coastal plain and upper-40s across the high terrain. Cold front
swings through on Saturday, 850mb temperatures at 12z are -2C to +2C
and by 00z Sunday temperatures drop -6C to -2C. Lingering moisture
could result in flurries. Highs are in the 30s for the high terrain
and 40s for the coastal plain.

The 500mb flow is quasi-zonal, a shortwave passage Sunday evening
into early Monday lends to added cloud cover given limited moisture
as PWATs are generally less than 0.4". Otherwise dry conditions are
expected through Tuesday with high pressure and mid-level ridging
across the east coast. Temperatures are seasonable, afternoon highs
are low-50s to upper-40s and nighttime lows are in the 30s.

By midweek, there is a shift in the pattern, a return to unsettled
conditions as the mid-level ridge and surface high shifts into the
North Atlantic. There remains a good bit of spread amongst guidance
given this timeframe is 6 to 7 days out. Something to watch as these
days lead up to Thanksgiving and busy travel days.

&&

.AVIATION /12Z THURSDAY THROUGH MONDAY/...
Forecaster Confidence Levels...

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

12z TAF Update:

Today... Moderate Confidence.

Mainly VFR. MVFR ceilings develop across the eastern waters which
could impact Cape/Islands terminals, plus Logan by 16z. Light and
variable winds, becoming NNE to NE for eastern MA terminals.

Tonight... High Confidence.

VFR. Light and variable winds.

Friday Moderate Confidence.

VFR, areas across the south coast have the best potential to lower
to MVFR after 20z. SW winds 8 to 12 knots, gusting to 20 knots at
the coast.

KBOS Terminal...Moderate confidence in TAF.

VFR. MVFR ceilings develop across the eastern waters which could
impact Logan by 16z. Light WNW winds turning more northerly by
daybreak, becoming variable Thursday afternoon.

KBDL Terminal...High confidence in TAF.

VFR. Light and variable winds.

Outlook /Friday Night through Monday/...

Friday Night: Mainly VFR, with local IFR possible. Chance RA.

Saturday: VFR. Breezy. Slight chance RA.

Saturday Night: VFR. Breezy.

Sunday through Sunday Night: VFR.

Monday: VFR. Breezy.

&&

.MARINE...
Forecaster Confidence Levels...

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

Key Messages:

* High confidence through the weekend. No headlines anticipated.

High pressure maintains light N/NE winds through Thursday with seas
less than 3 feet. An approaching cold front late Friday night into
Saturday should bring some rain, before another high builds into
region over weekend.

Outlook /Friday Night through Monday/...

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

Saturday: Winds less than 25 kt. Areas of seas approaching
5 ft. Chance of rain.

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

Sunday: Winds less than 25 kt.

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

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

&&

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

&&

$$

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