Weymouth Town, Massachusetts 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

201
FXUS61 KBOX 222355
AFDBOX

Area Forecast Discussion
National Weather Service Boston/Norton MA
655 PM EST Mon Dec 22 2025

.WHAT HAS CHANGED...
No significant changes. Minor snow accumulations still expected
Tuesday generally on the order of 1 to 3 inches. Potential for
accumulating snow for Friday into part of Saturday but
still a low-confidence forecast.

&&

.KEY MESSAGES...

- Minor snow accumulations of 1-3" likely Tue into Tue night.

- Intervals of snow/rain showers thru afternoon of Christmas Eve for
eastern MA coast; otherwise dry and seasonable through Christmas
Day.

- Lower-confidence forecast for the post-Christmas weekend, with
  potential for snow/ice/rain mix Fri into Sat.

&&

.DISCUSSION...
Key Message 1...Minor snow accumulations of 1-3" likely Tue into Tue
night.

Our next bout of unsettled weather arrives on Tuesday, a clipper
system that exits east into the Atlantic for the most part by early
on Wednesday. We have high confidence that this will be a low end
event, with minimal impacts, but the one wrinkle is that Tuesday is
such a big travel day ahead of Christmas. The surface low moves into
NY state early Tuesday with an isentropically forced shield of snow
overspreading SNE during the early morning (west) to mid/late
morning (east). Temperature profiles are subfreezing to start, with
warmer low level air infiltrating from the south so areas generally
south and east of the I-95 corridor will switch over to a mix and
rain. Given marginal temperatures, locations that do see
accumulation will see better accum on grassy surfaces than on the
roads. Snowfall rates also will be on the low end with poor omega in
the DGZ for most of the event. Given QPF values on the low end (0.15
to 0.30") and marginal temp profiles the most likely outcome is a
general 1-3" of snow north and west of the I-95 corridor with an
inch or less along/just south; again, accumulation likely also
struggles more on pavement. The low moves over the Atlantic
overnight taking the bulk of the moisture with it (i.e. snow/rain
comes to an end). PWATs drop below 0.25" except along the immediate
east coast where a few lingering snow/rain showers are expected to
linger. Temperatures hover near or above freezing overnight except
for the high elevations; this is where lingering moisture could
cause some slick roads.

Key Message 2...Intervals of snow/rain showers thru afternoon
of Christmas Eve for eastern MA coast; otherwise dry and
seasonable through Christmas Day.

As low pressure from Tuesday pulls away from the eastern coast,
residual/leftover ocean-enhanced bands of precip still seem possible
for the eastern coast of MA, Cape Cod/Islands into Wednesday
afternoon. Minor accums are possible but adverse travel impact isn`t
likely. High pressure then builds in from interior Southern New
England, offering dry weather with seasonable temps through
Christmas Eve night into Christmas Day (mid 30s/low 40s highs, lows
in the upper teens to mid 20s).

Key Message 3...Lower-confidence forecast for the post-
Christmas weekend, with potential for snow/ice/rain mix Fri into
Sat.

Models have picked up on a shallow cold air mass filtering southward
from Canada/northern New England Friday allowing for widespread sub-
freezing highs. More uncertainty in the details exists regarding a
wave of low pressure which treks ESE from the Gt Lakes region Fri
night into part of Sat. Models vary on the exact track of this wave,
ranging from the mid-Atlantic states to as far north as interior
SNE. Besides track differences, as well as unknown sub-synoptic-
scale details involving potential for possible bands in warm
advection pattern, some model forecast soundings suggest loss of
saturation in snow-growth-region at some point either late Fri night
or Sat, which could cut into any accums but instead force possible
freezing drizzle into the mix. Still a large amt of uncertainty
given the above for specifics on accumulations/possible impacts if
any; but based on ensemble 24-hr snow probs, moderate (25-50%) probs
for accumulating snows at plowable (2-4") levels mainly for CT
Valley, western MA/CT and into parts of RI, with low (nil to 20%)
probs of 6" or more.

&&

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

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

00Z TAF Update:

Tonight: High confidence.

VFR, though with lowering ceilings, especially toward pre-dawn
hrs at BDL. Light winds trend to S/SW around 5-10 kt by daybreak.

Tuesday into Tuesday Night: High confidence in trends but
moderate on timing.

Conditions deteriorate W to E between 13-16z from west to east
as precip moves in from NY. Most areas (except Cape/Islands as
light rain) start as IFR-visby wet snow, but BDL-PVD-BOS and
even BED to transition to a mix of rain and mixed wet snow with
visbys 3-5 SM. Ceilings lower to MVFR with initial precip onset
and eventually IFR by Tue aftn; ceilings could trend to
IFR/LIFR even as precip ends/moves offshore and visbys improve
between 22z-03z. Winds start S/SW around 5-10 kt, then become
S/SE at similar speeds, before shifting to light W by evening.

KBOS Terminal...High confidence in TAF. Moderate confidence in
start time of -SN.

KBDL Terminal...High confidence in TAF. Moderate confidence in
start time of -SN.

Outlook /Wednesday through Saturday/...

Wednesday: VFR. Windy with local gusts up to 30 kt. Chance
FZRA, slight chance SN.

Wednesday Night: VFR.

Christmas Day through Thursday Night: VFR. Breezy.

Friday: VFR. Chance SN.

Friday Night: Mainly VFR, with areas IFR possible. Breezy. SN
likely.

Saturday: Mainly VFR, with local MVFR possible. Breezy. Chance
SN.

&&

.MARINE...
Forecaster Confidence Levels...

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

W winds 10-20 kt tonight becoming S-SW Tue. Rough seas will
begin to subside below 5 ft over outer waters tonight. Rain or
mixed rain/snow develops Tue with lowering vsbys, exiting
overnight into Wednesday.

Outlook /Wednesday through Saturday/...

Wednesday: Strong winds with gusts up to 35 kt. Areas of rough
seas. Chance of rain, chance of snow.

Wednesday Night: Winds less than 25 kt. Areas of rough seas.

Christmas Day: Low risk for Small Craft Advisory winds with
gusts up to 25 kt. Local rough seas. Slight chance of rain.

Thursday Night: Low risk for Small Craft Advisory winds with
gusts up to 25 kt. Seas up to 5 ft.

Friday: Winds less than 25 kt. Seas up to 5 ft. Chance of snow.

Friday Night: Winds less than 25 kt. Rough seas up to 11 ft.
Snow likely. Areas of visibility 1 nm or less.

Saturday: Winds less than 25 kt. Rough seas up to 11 ft. Chance
of snow, slight chance of rain.

&&

.BOX WATCHES/WARNINGS/ADVISORIES...
CT...None.
MA...None.
RI...None.
MARINE...Small Craft Advisory until 7 PM EST this evening for ANZ250-
     256.
     Small Craft Advisory until 1 AM EST Tuesday for ANZ254-255.

&&

$$

DISCUSSION...Loconto/BW
AVIATION...Loconto/BW
MARINE...Loconto/BW