Office: BOX
FXUS61 KBOX 092249
AFDBOX
Area Forecast Discussion
National Weather Service Boston/Norton MA
549 PM EST Tue Dec 9 2025
.SYNOPSIS...
A moisture starved shortwave crosses the region tonight with a
period of mainly scattered light snow showers. A more
significant disturbance brings much milder temperatures and a
period of mainly rain Wednesday afternoon and evening with any
snow confined to the highest terrain of the Berkshires and
northern Worcester Hills. A cold front crosses the region later
Wednesday night...bringing mainly dry, but blustery and cold
weather returning Thursday into Friday. Low pressure may bring
snow with even some ice/rain to the region Saturday night into
Sunday depending on its track. This will be followed by another
shot of arctic air and well below normal temperatures early next
week.
&&
.NEAR TERM /THROUGH WEDNESDAY/...
Key Messages...
* Cold/dry conditions persist for the rest of the afternoon
* Southerly winds support increasing temperatures overnight
* Slight chance for some snow showers mainly across eastern MA
Rest of Today and Tonight
High pressure continues to support sunny skies, light winds, and
dry weather for the rest of the afternoon. As high pressure
shifts east overnight, return flow from the south will support
increasing temperatures through day break. Thus, we can actually
expect the overnight low to occur around midnight. A moisture
starved short-wave disturbance aloft moves overhead after
midnight. This may support a few widely scattered snow showers,
mainly across eastern MA. Not expecting any significant impacts
or accumulations with only a dusting at locations where snow
showers develop. Temperatures rise to the mid to upper 20s
across most of interior southern New England by sunrise. Low 20s
for northwest MA/high elevations and upper 30s to low 40s for
Cape/Islands.
&&
.SHORT TERM /WEDNESDAY NIGHT/...
Key Messages...
* Increasing cloudiness tomorrow with more mild temperatures
during the day
* Rain/snow Showers overspread the region from west to east
tomorrow afternoon and evening
* Cold front clears clouds/showers out overnight and is followed
by cold/blustery conditions
Wednesday and Wednesday Night
Warm advection and strong southerly winds support increasing
temperatures tomorrow with 925 and 850 hPa temps rising to near 0C
by the afternoon. This will support mild surface temperatures in the
upper 40s to low 50s across southeastern MA and RI tomorrow. Areas
across western MA and CT will be much cooler in the upper 30s to low
40s. Rain/snow showers begin to overspread the region from west to
east tomorrow afternoon into tomorrow evening. Mainly expecting
rain with some snow showers possible at the higher elevations
of The Berkshires and northern Worcester Hills. Accumulations
will be minor, but may approach 1-2 inches on the east slopes of
The Berks. Elsewhere, mainly in Worcester County, only
expecting a dusting if any accumulation at all.
A cold front moves over the region tomorrow night and clears
skies from west to east after midnight. This will be followed by
a brisk west/northwest wind and temperatures dipping back down
into the upper 20s/low 30s by Thursday morning.
&&
.LONG TERM /THURSDAY THROUGH TUESDAY/...
Key Messages:
* Falling temps Thurs with very cold and windy conditions Thurs aftn
to evening.
* Dry with modifying temps starting Fri into early Sat.
* Still monitoring low pressure which may bring accumulating snow
and/or a wintry mix of precip types to Southern New England Sat
night or into Sun, but the storm's track and strength are both
uncertain.
* Another shot of modified-Arctic air and blustery winds for early
next week.
Details:
Thursday:
Closed 500 mb low and its associated reservoir of modified-Arctic
air will entrench itself into Southern New England on Thurs.
Tightening NWly pressure gradient combined with a deepening mixed
layer supporting enhanced NW wind gusts will make for a windy and
very cold day. Wind gusts at top of the mixed layer are progged
around 45 to 50 kt, and efficient mixing should allow for gusts to
near-Advisory levels (35 to 45 mph). The bigger impact though is
that it will lead to falling temperatures and biting wind chills
through the afternoon; expect mid-morning highs then temps fall
though the teens to mid 20s by early evening. By early evening, wind
chills run in the single digits above zero in the terrain to the
mid/upper teens above zero for the remainder of Southern New
England, including the Cape and Islands. Because the NW winds stay
up for the entire evening under a continued tight NW pressure
gradient, nighttime lows may only fall into the teens above zero,
but wind chills in the 5 above to 5 to 10 below zero range by
sunrise Fri.
Friday:
Frigid start, although we enter into a warm advection pattern
starting Fri; while temps are still below normal, easing winds will
help take the edge off the wind chill. Full sun should allow highs
in the 20s to around freezing in/around the terrain and in the low
to mid 30s for lower elevations and the coasts. Dry weather for the
evening despite a modest increase in clouds, so some radiational
cooling likely to be offset by the warmer profiles (925 mb temps
warming to around -4 to -6C) and the cloud cover for lows in the mid
teens to lower to mid 20s.
The Weekend:
Increasing cloud cover on Sat but generally dry during the daytime
hours aside from a spot, non-impactful snow shower underneath the
cloud cover, with highs in the 30s, to near 40 along the south
coast.
Still monitoring developments regarding a potential storm system
that could threaten Southern New England later Sat night and/or
Sunday, as active northern stream energy pattern continues to favor
Clipper type systems. Besides the usual timing and storm track
uncertainties at this time range, global models still show a
disparity of potential outcomes due to differences in phasing
between a closed low over central Canadian Prairies and a weak vort
max coming around the northern Rockies/central Plains/upper Midwest.
These outcomes range from not much at all as phasing between the two
streams occurs too late/offshore (e.g. GFS/its ensemble) to
stronger/earlier phasing between the two energy streams (e.g.
ECMWF/Canadian camp) leading to a more robust low pressure which
treks somewhere ranging from interior northern New England and/or as
far south as the CT-RI-MA I-95 corridor. Depending on the exact
track...the international model solutions could favor an
accumulating snow for parts of or much of Southern New England
Sunday, with better chance for interior Southern New England,
although a more interior storm track would introduce more wintry mix
(PL/FZRA) or rain into the mix. Thus as mentioned, quite a few
uncertainties that still need to be ironed out, but these are
details we'll be keeping tabs on as we move through the workweek and
it is too early to lock into any one outcome as yet.
Monday and Tuesday:
System exits early on Monday which brings decreased cloudiness, but
with it comes another dump of colder, modified-Arctic air and
blustery conditions.
&&
.AVIATION /00Z WEDNESDAY THROUGH SUNDAY/...
Forecaster Confidence Levels...
Low - less than 30 percent.
Moderate - 30 to 60 percent.
High - greater than 60 percent.
00Z TAF Update...
VFR. Light southwest winds
Tonight...High Confidence
Mainly VFR with some MVFR cloud bases right around 3000-4000
feet possible. Low chance for some snow showers between roughly
02-07Z as a weak disturbance moves over the region. Winds
becoming more steady out of the southwest with speeds increasing
to around 10 knots with some 20 knot gusts possible over The
Cape/Islands.
Tomorrow... High Confidence in trends, moderate in timing
VFR likely through 18Z, then MVFR ceilings overspread the region
from west to east with -RA. Not expecting MVFR ceilings to reach
BOS/PVD until 20-22Z time frame. Cape/Islands terminals don't
fall below VFR until after 00Z.
Tomorrow Night... High Confidence
MVFR ceilings reach Cape/Islands between 00-06Z. Conditions
gradually improve back to VFR between 06-12Z as a cold front
sweeps across the region. Winds shift to the west/northwest
behind the front with sustained winds around 15 knots.
KBOS Terminal...Moderate Confidence in TAF.
Low chance for -SN overnight between roughly 03-09Z.
KBDL Terminal...High Confidence in TAF.
Outlook /Thursday through Sunday/...
Wednesday Night: Mainly VFR, with local IFR possible. Windy
with areas of gusts up to 35 kt. Chance RA, slight chance FZRA,
patchy BR.
Thursday through Thursday Night: VFR. Windy with gusts up to
35 kt.
Friday: VFR. Windy with local gusts up to 30 kt.
Friday Night through Saturday: VFR. Breezy. Slight chance SN.
&&
.MARINE...
Forecaster Confidence Levels...
Low - less than 30 percent.
Moderate - 30 to 60 percent.
High - greater than 60 percent.
Tonight through Wednesday night...High confidence.
Gale Watch upgraded to gale warning for tonight and tomorrow as
a LLJ allows for SW wind gusts of 35 knots to develop over the
coastal waters. Showers move over the coastal waters tomorrow
evening and tomorrow night. Gale force winds mainly from the
southwest through Thursday morning.
Outlook /Thursday through Sunday/...
Wednesday Night: Low risk for gale force winds with gusts up to
35 kt. Rough seas up to 12 ft. Chance of rain, patchy fog.
Thursday: Moderate risk for gale force winds with gusts up to
35 kt. Areas of rough seas. Slight chance of rain.
Thursday Night: Moderate risk for gale force winds with gusts
up to 40 kt. Areas of rough seas. Slight chance of snow.
Friday: Strong winds with gusts up to 35 kt. Areas of rough
seas.
Friday Night: Low risk for Small Craft Advisory winds with
gusts up to 25 kt. Local rough seas. Slight chance of rain.
Saturday: Low risk for Small Craft Advisory winds with gusts up
to 25 kt. Local rough seas. Chance of rain, slight chance of
snow.
&&
.BOX WATCHES/WARNINGS/ADVISORIES...
CT...None.
MA...None.
RI...None.
MARINE...Small Craft Advisory from 10 PM this evening to 6 AM EST
Thursday for ANZ230-236.
Gale Warning from 1 AM Wednesday to 6 AM EST Thursday for
ANZ231>235-237-250-251-254>256.
&&
$$
SYNOPSIS...Frank/RM
NEAR TERM...RM
SHORT TERM...RM
LONG TERM...Loconto
AVIATION...Loconto/FT
MARINE...Loconto/RM
