339
FXUS61 KBOX 012006
AFDBOX

Area Forecast Discussion
National Weather Service Boston/Norton MA
306 PM EST Mon Dec 1 2025

.SYNOPSIS...
Monday brings the return to drier, colder and blustery weather. Low
pressure tracking south of New England brings accumulating snow to
interior portions of CT and MA Tuesday and Tuesday night, with rain
most likely in the lower elevations. Beyond that high pressure
brings dry weather to end the week except for a moisture starved
front Thursday.

&&

.NEAR TERM /UNTIL 6 AM TUESDAY MORNING/...
Key Message:

* Cold tonight with increasing clouds

High pres moves across New Eng this evening before shifting to
the NE overnight. We should see a brief period of decent
radiational cooling this evening with light winds and just some
thin cirrus before clouds thicken and lower overnight. Low
temps will be reached by midnight with lows ranging through the
20s with some upper teens possible across interior N MA. It
will remain dry through the night as deeper moisture stays to
the west through 12z.

&&

.SHORT TERM /6 AM TUESDAY MORNING THROUGH TUESDAY NIGHT/...
225 PM Update:

Key Messages:

* Coastal storm system to bring a higher elevation accumulating snow
  with lower elevation mainly rain event to Southern New England.

* Accumulation of wet, dense snow in the interior will make for
  difficult travel during the afternoon and Tue PM commute, and
  significant accumulations of snow in the high terrain could
  lead to tree and powerline damage due to the weight of snow.

* Mainly rain for the majority of the event in lower elevations Tue,
  with 1 to 1.5 inches of rain; however bands of light-accumulating
  greasy snow are anticipated Tue night into early Wed AM in CT,
  eastern MA and RI.

Details:

A moisture-laden area of low pressure now organizing near the
northern Gulf is expected to track ENE through the mid-Atlantic
states and then continue along the New England coast on Tue,
before pulling away into Nova Scotia late Tue night. This low
pressure is expected to bring an accumulating wet/dense snowfall
in the interior and higher terrain Tue into Tue night, with
primarily rain in the lower elevations though ending as a period
of light-accumulating snow Tue night due to wrap-around
moisture as the storm exits.

While the exact track of the low pressure is still somewhat
uncertain, today`s forecast models have shown a loose consensus
toward a track inside of the 40N/70W benchmark. This track will
allow for above-freezing temps on easterly winds to advect
inland enough to force a predominant precip type in the lower
elevations as largely rain; higher-resolution guidance 2-m temps
struggle to get the I-95 corridor down to near/below freezing
levels until Tue night. The lack of a closed 700-500 mb
circulation will also make it difficult to maintain or even
sustain colder enough air in the lower elevations. In interior
Southern New England, marginally cold enough air through the
event to lead to accumulation of wet snow, and the higher
elevations (Berkshires, eastern Franklin/northern Worcester and
northwest Middlesex) could see significant accumulations to the
point where we could have some downed trees/powerlines due to
snow loading factors in those locations.

Snow accumulations and headlines are highly driven by
elevation. We converted the Winter Storm Watch to Winter Storm
Warnings in the Berkshires and into northern MA where forecast
wet snow accumulations are in the 6 to 9 inch range. Besides
just slippery road conditions and reduced visby with snow rates
at or around 1 inch per hour, the potential exists for tree and
powerline damage, and past storms producing significant wet
snows have shown the potential for tree and powerline damage
reports as snow totals start to exceed 4 inches. Winter Weather
Advisories surround those areas with snow totals ranging from 3
to 6 inches. These headlines run from 7 AM Tue to 7 AM Wed. With
the tendency in today`s guidance to show a wrap-around band of
snow as temperatures fall Tue night into the Merrimack Valley,
Metrowest and part of northeast MA, we opted for a Winter
Weather Advisory for those areas starting around 4 PM Tue until
7 AM Wed, and it`s possible other areas may need to be added to
this Advisory in later updates. Areas in this Winter Weather
Advisory during the day on Tue should stay as rain during the
daytime hours, which explains the difference in timing.

Precipitation is not expected to begin on Tue until the mid-
morning to early afternoon, with steadier and heavier precip
breaking out during the afternoon to mid-evening hours. Thus
greater overall impacts to the Tuesday afternoon commute, and
that`s especially the case for interior Southern New England
with sustained bands of moderate to at times heavy snow with
reduced visbys. In lower elevations east and south of I-84 to
I-495, moderate to heavy rains to the tune of 1-1.4 inches of
rain are anticipated, with air temps in the upper 30s to the mid
40s. As low pressure pulls offshore Tue evening, colder air
advancing southward on the backside of the system should allow
for a changeover to wet snow, with potential for steadier light
snowbands along the Merrimack Valley to the North Shore.
Additional light, greasy snows southward into most of CT and RI
and eastern MA for the overnight as colder air works southward
and these wrap-around precip bands work through; this overnight
band of snow offers the best chance for accumulating snows at
around a half to 2 inches, and while not reaching Advisory
levels they could make for some slippery spots for the overnight
hours.

&&

.LONG TERM /WEDNESDAY THROUGH MONDAY/...
Key Messages:

* A few snow showers possible the second half of Thursday with the
  passage of an Arctic cold front, otherwise dry weather Wednesday
  through Friday. Turning unsettled for the upcoming weekend.

* Temperatures are trending well-below-average Wednesday through the
  upcoming weekend. An Arctic cold front Thursday night to bring the
  coldest air of the season, highs struggling to get above freezing
  by Friday afternoon.

Little in the way of precipitation between Wednesday and Friday with
an area of high pressure building to the southwest of the region. A
strong cold front, an Arctic Cold Front, brings a low chance for a
few snow showers Thursday afternoon and evening. PWATs values are on
the lower side 0.4 to 0.6", at this time do not expecting significant
accumulations. Probabilities for 0.1" of new snow at this time are
less than 20% for the Worcester Hills and less than 50% for the east
slope of the Berkshires. The bigger story is the cold that follows
the frontal passage. 925mb temperatures are lowering to -20C to -15C
Thursday night, temperatures lower into the single digits and teens.
But, a gusty northwest wind make it feel much colder as wind chills
are below 0F across the higher terrain and single digits for the
coastal plain. Friday afternoon, highs struggle to climb out of the
20s, "warmest" are south coast of RI/MA in the mid-30s.

Guidance trends are toward an active setup for the upcoming weekend,
especially Saturday. Global ensembles continue to develop an area of
low-pressure off the Mid Atlantic coast Saturday morning/afternoon.
It is too soon to get into any details, but there is potential for
another rain/snow/mixed event. Stay tuned!

&&

.AVIATION /20Z MONDAY THROUGH SATURDAY/...
Forecaster Confidence Levels...

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

18Z update...

Through Tonight...High Confidence.

VFR. Lowering cigs late tonight. NW gusts to 25 kt, diminishing
mid-late afternoon, then becoming light to calm tonight.

Tuesday...Moderate Confidence.

Lowering to IFR-LIFR as precip overspreads the region, 12-15z in
west and 15-18z in the east. Ptype rain for coastal terminals,
snow for BAF and ORH, and SN to RA-SN mix at BED and BDL. E-NE
wind 5-15 kt. Minor accumulations at BDL-BAF-BED with more
significant accums possible at ORH.

Tuesday night...Moderate confidence.

Widespread IFR-LIFR improving to VFR late from west to east.
Interior snow in the evening may change to a period of snow
along the I-95 corridor, including BOS and PVD for a few hours
before ending around or just after midnight. Minor accum (up to
an inch) possible at BOS. NE wind becoming N-NW with gusts to
25 kt developing, with 30-40 kt gusts possible for
Cape/Islands.

KBOS Terminal...High confidence in TAF.

KBDL Terminal...Moderate confidence in TAF. Lower confidence in
timing of ptype changes.

Outlook /Wednesday through Saturday/...

Wednesday through Wednesday Night: VFR. Breezy.

Thursday: VFR. Windy with local gusts up to 30 kt. Slight
chance SN.

Thursday Night: VFR. Windy with local gusts up to 30 kt.

Friday: VFR.

Friday Night: VFR. Slight chance SN.

Saturday: VFR. Chance RA, chance SN.

&&

.MARINE...
Forecaster Confidence Levels...

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

Today through Tuesday Night... High confidence.

Winds quickly diminish this afternoon as high pressure builds in
from the west. Light winds this evening becoming S-SE toward
daybreak Tuesday. Rough seas over southern waters will subside and
fall below 5 ft by this evening. Tuesday rain overspreads the waters
and SSE winds early increase and turn out of the east then northeast
late as a low pressure system crosses the southern waters. This
leads to gusts as strong as 25-30 kts by late Tuesday over the
southern waters and 30-40 kts for the eastern waters.

A Gale Warning has since been issued Tuesday evening through the
overnight hours for the eastern waters, while a Small Craft Advisory
is issued for the southern waters.

Outlook /Wednesday through Saturday/...

Wednesday: Low risk for Small Craft Advisory winds with gusts
up to 30 kt. Rough seas up to 11 ft.

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

Thursday: Moderate risk for Small Craft Advisory winds with
gusts up to 30 kt. Areas of rough seas. Slight chance of rain.

Thursday Night: Strong winds with gusts up to 40 kt. Areas of
rough seas.

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

Friday Night through Saturday: Winds less than 25 kt. Chance of
rain.

&&

.BOX WATCHES/WARNINGS/ADVISORIES...
CT...None.
MA...Winter Storm Warning from 7 AM Tuesday to 7 AM EST Wednesday
     for MAZ002>004-008-009-026.
     Winter Weather Advisory from 4 PM Tuesday to 7 AM EST
     Wednesday for MAZ005-006.
     Winter Weather Advisory from 7 AM Tuesday to 7 AM EST
     Wednesday for MAZ010>012.
RI...None.
MARINE...Gale Warning from 7 PM Tuesday to 7 AM EST Wednesday for
     ANZ230.
     Gale Warning from 7 PM Tuesday to 1 PM EST Wednesday for
     ANZ231-232-250-251-254-255.
     Small Craft Advisory from 4 PM Tuesday to 7 PM EST Wednesday
     for ANZ233>235-237.
     Small Craft Advisory from 4 PM Tuesday to 7 AM EST Wednesday
     for ANZ236.
     Small Craft Advisory from 4 PM Tuesday to 1 AM EST Thursday
     for ANZ256.

&&

$$

SYNOPSIS...Loconto/Dooley
NEAR TERM...KJC
SHORT TERM...Loconto
LONG TERM...Dooley
AVIATION...KJC/Loconto
MARINE...Loconto/Dooley