Area Forecast Discussion
National Weather Service Boston/Norton MA
612 AM EST Mon Dec 15 2025
SYNOPSIS
Arctic airmass moves in this morning and for much of the day today
with wind chill values dropping to between 0 to 10 below. Cold
weather continues tonight into Tuesday but with much lighter
winds. Dry weather continues on Wednesday but with
significantly milder temperatures. Unseasonably mild
temperatures Thursday into early Friday will be accompanied by a
period of heavy rain and potentially a brief period of strong
southerly wind gusts. Sharply colder air works back into the
region later Friday into early Saturday with a second round of
strong northwest wind gusts. This cold will not last long with
milder temperatures returning by the end of next weekend.
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
Key Messages...
* Bitterly cold wind chills between 0 and 10 below zero this morning
* Gusty WNW winds through this afternoon with highs mainly in
the 20s
Very cold temps early this morning coupled with the blustery
winds were resulting in bitterly cold wind chills between 0 and
10 below zero. Ocean effect clouds across the outer-Cape and a
few lingering light snow showers/flurries should come to an end
by mid-morning.
Otherwise...sunshine to start the day with some scattered
clouds during the afternoon. Steep pressure gradient and decent
mixing brings down some gusty winds from a 40-50kt low level
jet. Expecting gusts between 25 and 35 mph around the region
especially across the higher terrain. Coldest day of the season
so far ahead with 850s struggling to rise much above
-15C. Highs should be held in the 20s across the region. Stiff
winds keep wind chill temperatures firmly in the upper single
digits and lower teens during the afternoon.
.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM TUESDAY/...
Key Messages...
* Diminishing winds and cold tonight
* Final day of near or below freezing temperatures before a warm up
for the rest of the week
Tonight...
Mostly cloudy skies expected overnight but not much in the way of
precipitation. There is a low chance for a stray snow shower from
the Great Lakes to make it into the Berkshires later tonight as a
weak mid level disturbance passes well to the north. Should see
gusty winds quickly wind down after sunset as model soundings show
the boundary layer decoupling. Another cold night ahead with thinning
cloud cover bringing increasingly favorable conditions for
radiational cooling. Should see lows in the upper single digits
in the terrain and upper teens along the coastal plain.
Tuesday...
Final day near freezing temps for the rest of the week for most of
us except near the coast where temps will climb near 40.
Temperatures aloft warm quite a bit from around -10C Tuesday morning
to perhaps as high as +3C by 00z. Surface high pressure positioned
to the south will support mainly dry conditions and light
southwesterly winds.
.LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/...
Key Messages...
* Dry, breezy & significantly milder Wed with highs well into the
40s to perhaps near 50 in a few spots
* Unseasonably mild late Thu into Fri morning with showers and
potentially a period of heavy rain/briefly strong wind gusts
* Brief shot of much colder air later Fri/Fri night with high
confidence in a period of strong northwest wind gusts
* A few brief rain/snow showers possible Sat night into Sun,
otherwise turning milder again with highs Sun in the 40s to near 50
Details...
Tuesday night and Wednesday...
High pressure off the mid-Altantic coast moves further east out into
the Atlantic Tue night into Wed. The result will be a southwest flow
of milder air working into southern New England. Lows Tue night will
be in the upper teens and 20s...but temps should begin to rise near
the south coast as southwest winds pickup. A mixture of clouds and
sunshine Wed with gusty SW winds and 850T rising above 0C will
result in a significantly milder afternoon. High temps Wed should
reach well into the 40s...perhaps even flirting with 50 in a few
spots.
Thursday into Friday...
Given that the pattern has flipped to a -PNA...a strong upper level
disturbance will race across the U.S./Canadian border. This will
spawn a strong surface low pressure system that will track well to
our north across Quebec late Thu into early Fri. The magnitude of
this surface low pressure system will result in a strong southerly
LLJ ahead of the approaching cold front. The ensemble situational
awareness table indicates this LLJ 2-3 standard deviations above
normal with Pwats of 1+ inches. The combination brings a round of
showers with potentially brief heavy rainfall sometime in the late
Thu to early Fri time frame. Temperatures will likely rise into the
50s and perhaps even approach 60 out ahead of the cold front Thu
night into early Fri. The GFS/EC/CMC all indicate a southerly LLJ of
nearly 80 knots. The global guidance often underestimates the
magnitude of the LLJ...but we are way outside the window of any high
resolution guidance. Nonetheless...that is a pretty strong signal
from the global guidance. So we will have to watch for a brief
period of strong southerly wind gusts if we are able to mix out the
inversion. Always difficult to determine...and sometimes strongest
winds remain just off the deck but we will need to watch this in the
coming days.
Behind this cold front...there is a brief shot of much colder air
that will surge into the region late Fri/Fri night. The pressure
rise/fall couplet and a sharp drop in temperatures will result in a
period of strong WNW wind gusts behind the front. We are much more
confident in this second round of strong wind gusts because the
atmosphere will be so well mixed.
Next Weekend...
Brief shot of colder weather follows on Saturday...with dry weather
and high temperatures mainly in the 30s to near 40. Given that we
are now in zonal flow aloft...this return to chilly temperatures
will be short-lived. Shortwave trough departs and a warm front may
bring a few brief rain/snow showers to the region late Sat night
and/or Sun. Otherwise...breezy and milder Sun with highs well into
the 40s.
.AVIATION /12Z MONDAY THROUGH FRIDAY/...
Forecaster Confidence Levels...
Low - less than 30 percent.
Moderate - 30 to 60 percent.
High - greater than 60 percent.
12z TAF Update...
Today...High Confidence
Lingering marginal MVFR ocean effect clouds/flurries across the
outer-Cape/ACK dissipate by mid morning or so. Otherwise...VFR
with NW winds gusts of 25 to 35 knots.
Tonight...High Confidence.
VFR with just a low risk for very brief MVFR cigs flirting with
the Islands. Diminishing winds become light from a WSW
direction.
Tuesday... High Confidence
VFR. SW winds 5-10 knots.
KBOS Terminal...High confidence in TAF
KBDL Terminal...High confidence in TAF.
Outlook /Tuesday Night through Friday/...
Tuesday Night: VFR. Breezy.
Wednesday: VFR. Windy with local gusts up to 30 kt.
Wednesday Night through Thursday: VFR. Breezy.
Thursday Night: MVFR/IFR conditions possible. Strong winds with
gusts up to 45 kt. SHRA.
Friday: Mainly VFR, with local IFR possible. Strong winds with
gusts up to 45 kt. SHRA.
.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.
Northwest Gales continue through 20z this afternoon with wind
gusts between 25 and 35 kt. Areas of light to moderate freezing
spray will finally dissipate by afternoon. Elsewhere, small
craft advisory conditions expected in Narragansett Bay and
Boston Harbor. Gales subside to small craft advisory by late
afternoon/early evening and further diminish tonight.
Outlook /Tuesday Night through Friday/...
Tuesday Night: Moderate risk for Small Craft Advisory winds
with areas of gusts up to 30 kt. Seas locally approaching 5 ft.
Wednesday: Strong winds with gusts up to 35 kt. Areas of rough
seas.
Wednesday Night: Low risk for Small Craft Advisory winds with
gusts up to 25 kt. Areas of rough seas.
Thursday: Low risk for Small Craft Advisory winds with gusts up
to 30 kt. Areas of seas approaching 5 ft.
Thursday Night: Moderate risk for gale force winds with gusts
up to 45 kt. Areas of rough seas. Rain showers.
Friday: gale force winds with gusts up to 45 kt. Rough seas up
to 16 ft. Rain showers.
.BOX WATCHES/WARNINGS/ADVISORIES...
CT...None.
MA...None.
RI...None.
MARINE...Small Craft Advisory until 3 PM EST this afternoon for ANZ230-
236.
Gale Warning until 1 PM EST this afternoon for ANZ231>235-237-
250-251-254>256.
Freezing Spray Advisory until 10 AM EST this morning for
ANZ232>234.
SYNOPSIS...Frank/FT
NEAR TERM...FT
SHORT TERM...FT
LONG TERM...Frank
AVIATION...FT/Frank
MARINE...FT/Frank
Forecast And Data Provided By NOAA-NWS Boston / Norton, MA