391
FXUS61 KBOX 010652
AFDBOX

Area Forecast Discussion
National Weather Service Boston/Norton MA
152 AM 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 /THROUGH TONIGHT/...

Key Message...

* Dry and seasonable with breezy winds.

High pressure crosses overhead Monday so subsidence beneath the high
will keep skies clear and dry while gusty NW winds will persist for
the first half of the day. Winds diminish through the afternoon as
the center of the high moves directly overhead and the pressure
gradient drops. This will lead to a decoupled boundary layer and
calm winds overnight which would lend to some radiational cooling
early before cloudcover increases as the high moves offshore. Lows
dip into the low to mid 20s.

&&

.SHORT TERM /TUESDAY THROUGH TUESDAY NIGHT/...

Key Messages:

* Coastal system Tuesday morning and night brings plowable snow
  to higher elevations of southern New England. Winter Storm
  Watch issued for the central and western regions of
  Massachusetts.

A mid level shortwave over the Great Plains on Monday then moves
into the eastern U.S. Tuesday. As it digs into the southeast it
induces a deepening surface low off the Mid-Atlantic coast that
lifts up along the New England coast Tuesday into Nova Scotia by
early Wednesday. Guidance is in fairly good agreement at this point
that the low tracks along or just inside the 70/40 benchmark.
However, there are several factors that point to this being a
largely high elevation snow/low elevation rain storm. First, this is
a progressive system with no high pressure over Quebec to block its
exit and keep sub-freezing air locked in at the surface. As such,
warm advection kicks in quickly on southerly LLJ; so while we start
off below freezing in the low levels temps will quickly warm above
freezing outside of the Berkshires and Worcester Hills. This is
especially true along the south coast as SSTs remain in the 50s.
Even if precip starts as snow initially, accumulation is unlikely,
or, worst case would likely be some coatings on grassy surfaces. The
timing of this system (largely during the day) doesn`t bode well for
snow chances in the low elevations. In these early season cases
"positive snow depth change" products are often more representative
in the numerical guidance. This setup featuring an open wave at 750
mb until downstream of SNE isn`t typically a good indicator of a big
snow storm. Where we do see snow, snow ratios in the guidance have
trended down over the last 24-48 hours and model soundings indicate
max omega/lift misses the DGZ so excessively heavy snowfall rates
aren`t expected. The trend with this forecast update was to lower
the snowfall totals based on the factors discussed above.

Regardless, there is a lot of moisture available (PWATs over 1.25"
over the Cape and islands) and strong forcing for ascent; we
previously mentioned the strong LLJ, and we`ll also benefit from a
coupled upper jet streak (SNE placed between the RRQ of an exiting
jet and a LFQ of another). This will lead to rainfall totals of over
an inch in southeast MA by the time precip comes to an end early
Wednesday morning. While colder temps pulled in on the backside may
produce a flip to snow briefly on the tail end, QPF will be tapering
off and not expecting appreciable accumulations.


&&

.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
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 by next 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.

Wednesday through Sunday is quiet and cold. 500mb pattern
becomes somewhat zonal across much of the CONUS with surface
high pressure builds in behind the departing coastal low on
Wednesday. Then an Arctic cold frontal passage late in the day
Thursday. Moisture is limited, PWATS less than 0.6" should be
enough for snow showers with the frontal passage. With the
Arctic cold front, 925mb temperatures fall to -20C to -15C
Thursday night, temperatures lower into the single digits to low
teens. But, a gusty northwest wind makes it feel much colder,
wind chills are below 0F across the higher terrain and well into
the single digits for the coastal plain. Towards the end of the
extended, guidance shows a more active pattern, leading to
unsettled conditions come next weekend.

&&

.AVIATION /06Z MONDAY THROUGH FRIDAY/...
Forecaster Confidence Levels...

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

06Z update...

Through 12Z...High confidence.

Rain exits Cape Cod/ACK by 08Z followed by clearing and VFR. S
gusts 20-25 kt with areas of LLWS this evening over Cape/Islands
associated with a low level jet.

Today...High Confidence.

VFR. NW gusts to 25 kt, diminishing late afternoon.

Tonight...High confidence.

VFR. Light to calm wind.

Tuesday...Moderate Confidence.

SN for BDL/BAF/ORH and rain for other terminals arrives 12-18z.
VFR lowers to IFR by 18Z. Lower confidence in whether
BOS/BED/PVD may see some SN...more than likely RA or some non-
accumulating SN.

KBOS Terminal...High confidence in trends.

KBDL Terminal...High confidence in trends.

Outlook /Wednesday through Friday/...

Wednesday: VFR. Breezy. Patchy BR.

Wednesday Night through Thursday: VFR. Breezy.

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

Friday: VFR.

&&

.MARINE...
Forecaster Confidence Levels...

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

Through Tuesday...High confidence.

W winds become NW through the day today with gusts 25-30 kt
continuing. SCA for all waters. Winds quickly diminish through Mon
afternoon as high pres builds in from the west. Light winds Mon
evening becoming S-SE toward daybreak. Rough seas over southern
waters will begin to subside during Mon and fall below 5 ft by Mon
evening. Periods of rain ending tonight from W to E. Dry with good
vsbys Mon and Mon night.

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.

Outlook /Wednesday through Friday/...

Wednesday: Low risk for Small Craft Advisory winds with gusts
up to 25 kt. Rough seas up to 11 ft. Widespread fog.

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.

Thursday Night: Strong winds with gusts up to 35 kt. Rough seas
up to 13 ft.

Friday: Winds less than 25 kt. Local rough seas.

&&

.BOX WATCHES/WARNINGS/ADVISORIES...
CT...None.
MA...Winter Storm Watch from Tuesday morning through late Tuesday
     night for MAZ002>006-008>012-026.
RI...None.
MARINE...Small Craft Advisory until 3 PM EST this afternoon for ANZ230-
     232>235-237.
     Small Craft Advisory until 5 PM EST this afternoon for ANZ231-
     250-251-254>256.
     Small Craft Advisory until 1 PM EST this afternoon for ANZ236.

&&

$$

SYNOPSIS...BW
NEAR TERM...BW
SHORT TERM...BW
LONG TERM...Dooley
AVIATION...BW
MARINE...BW