Lexington Weather

Lexington, Massachusetts, USA

31°F

12/14/2025 2:18pm

Lexington Conditions: Light snow, Mist, Overcast
Temperature: 30.7°F / -0.7°C
Dew Point: 28.2°F
Relative Humidity: 90%
Wind: Calm, 10-min avg: Calm, gust: 1 mph
Barometer: 29.79 in Steady
Visibility: 2 miles
Snow Today: 0.7 in

Area Forecast Discussion
for Boston / Norton, MA

        
000
FXUS61 KBOX 141519
AFDBOX

Area Forecast Discussion
National Weather Service Boston/Norton MA
1019 AM EST Sun Dec 14 2025

.SYNOPSIS...
Fast moving low pressure will bring accumulating snow to the 
region into midday, especially south of the Massachusetts 
Turnpike. This snow will linger into this afternoon across 
Rhode Island, and especially across far eastern Massachusetts, 
where it may persist into this evening. A brief shot of arctic
air follows tonight into Monday, with wind chill values dropping 
to between 0 to 10 below zero. Cold weather continues Monday
night into Tuesday but with much lighter winds. A warming trend 
begins Wednesday and especially by Thursday when high
temperatures of 50+ are possible. Unseasonably mild temperatures 
will be accompanied by a round of showers sometime later
Thursday into early Friday with perhaps a period of strong
southerly winds and heavy rain. A brief shot of much colder
weather with another period of strong winds possible later
Friday into Saturday.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
Key Messages...

* Accumulating snow ends by lunchtime across western MA/CT, but 
  persists into the afternoon especially across eastern MA

* Hourly snowfall rates generally on the lighter side, but 
  brief bursts of moderate snow possible near the south coast

Heaviest snowfall band established along the south coast of New
England and across the Cape Cod Canal. Observed snowfall ratios
prior to daybreak were a little lower than projected, which can
make a difference over a longer period of time. Snowfall rates
were not remarkable across most of our region. Will have to see
if the longer duration during the daytime can compensate for the
lower snowfall ratios overnight.

Still expecting snowfall to diminish from NW to SE this
afternoon. Will continue the Winter Weather Advisories as they
are for now. Will likely be able to cancel some of these
advisories prior to the 7 PM expiration time.

Previous Discussion...

Trend in high res guidance has been to shift the timing of the
end of the steadiest snow from mid morning to the afternoon for
much of Rhode Island and Eastern Massachusetts. Model guidance,
namely the HRRR and NAM3km have also begun to resolve an
inverted trough and wrap around ocean effect snow extending from 
low pressure as it pulls away. Trough will be a good focus for 
vertical motion and moisture as omega increases to -10 to -15  
ubar/sec. Sharply colder air filtering behind departing low
pressure will introduce non-zero MLCAPE values which could help 
with ocean enhancement of any snow bands. Despite these 
favorable parameters, daytime will likely be limited by marginal
sfc temps in the mid and even upper 30s. Temps may be locally 
lower under any ocean effect bands but its really going to take 
considerable rates to cool the PBL from the influence of 45-47F 
water temps. As a result, still think that advisory level snow 
totals 2-4" for RI/SE MA with localized 5-6" amounts possible 
near the south coast and Cape Cod.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM MONDAY/...
Key Messages...

* Very cold with wind chill values near or below zero

* Windy conditions with gusts up to 40 mph Sunday Night and Monday

The coldest airmass of the season thus far will move in behind
the snow for Sunday night as 850mb temps crash into the -15C 
to -20C range. This will result in overnight low temperatures
bottoming out in the single digits across the interior, to the
lower teens near the coastal plain. A strong pressure gradient
will result in gusty winds overnight, around 25-40 mph. This
will bring the windchill index/feels-like temperatures down to
the 0F to -5F range, with -5F to -15F in the high terrain. 

Monday

High pressure helps to keep an Arctic air mass in place through
the day on Monday as GFS and Euro ensembles keep temperature
anomalies near 10 degrees colder than normal. Other story Monday 
will be a steep pressure gradient keeping a stiff NW wind in
place for the region. Wind gusts between 25 and 35 mph will make 
high temperatures in the teens (at higher elevations) and 20s 
elsewhere feel more like the single digits to lower teens at 
their warmest.

&&

.LONG TERM /MONDAY NIGHT THROUGH SATURDAY/...
Key Messages...

* A few brief snow showers possible Mon night, otherwise
  diminishing winds with low temps mainly in the teens

* Dry & chilly Tue. Highs mainly in the lower to middle 30s

* Turning milder Wed with continued dry weather & highs into the
  40s 

* Showers with heavy rain & potential briefly strong southerly
  wind gusts later Thu into early Fri with unseasonably mild  
  temps

* Brief shot of much colder temps returns behind the front later
  Fri into Sat with another round of strong winds possible

Details...

Monday night into Tuesday...

A weak shortwave may bring a few brief snow showers to the
region Monday night. Otherwise...still chilly Mon night into 
Tue but with light winds. Low temperatures Mon night will mainly
be in the teens. Highs on Tue will range from the upper 20s in 
the highest terrain to mainly the lower to middle 30s elsewhere.

Wednesday...

The developing -PNA and high pressure to our south sliding
further east will allow for the beginning of a pattern change 
and milder temperatures. While it will remain dry on Wed, gusty 
southwest winds developing will push high temperatures well into
the 40s.

Thursday into Friday morning...

Strong shortwave energy over the northern plains will move
eastward into the Great Lakes. As this happens, strong surface 
low pressure perhaps sub 980 mb will pass well to our north 
across Quebec. Given the potential strength of the surface low 
pressure system...the long range guidance is indicating a strong
southerly LLJ nearly 3 standard deviations outside climatology.
Not only will this bring up unseasonably mild temperatures and 
Pwats exceeding 1 inch. This will combined with strong forcing 
ahead of the cold front and bring showers with perhaps brief 
heavy rain sometime later Thu into Fri. In addition...given the 
magnitude of the southerly LLJ we will have to watch for a brief
period for strong surface wind gusts if the inversion is able 
to mix out. It is way too early to assess that...but depending 
on the timing temperatures may rise well into the 50s Thu 
night/early Fri and may even flirt with 60 degrees. If we are 
able to get mild enough...the potential for a period of strong 
winds to be realized will increase. Again...way too early to say
much more than that but something to watch in the coming days.

Later Friday into Saturday...

Briefly turning much colder later Friday into Saturday behind the 
cold front. Mainly dry weather expected, but another period of
strong winds this time from the west is possible immediately 
behind the cold front.

&&

.AVIATION /14Z SUNDAY THROUGH THURSDAY/...
Forecaster Confidence Levels...

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

Today...Moderate Confidence 

Light snow will result in a lot of IFR conditions this morning
with vsbys in the 1-3 mile range. Bands of moderate snow and and
LIFR conditions should mainly be confined to RI/SE MA. The light
snow will end across western MA/CT by lunchtime, but linger into
this afternoon east of the CT River Valley, especially across 
eastern MA. So improvement to MVFR and even VFR conditions will 
be confined to mainly interior southern New England this 
afternoon.

Tonight...High Confidence 

MVFR-IFR and even brief LIFR conditions are expected in areas
towards the Cape and Islands in ocean effect snow showers. This
activity should dissipate though after midnight. Otherwise, NW 
wind gusts of 20 to 25 knots with a few gusts near 30 knots 
across the high terrain and near the coast develop tonight.

Monday...High Confidence 

Mainly VFR with NW gusts of 30-35 knots. A few CU but should be 
above MVFR ceilings. 

KBOS Terminal...Moderate confidence in TAF. Light snow continues
much of the day with vsbys generally in the 1-3 mile range. The
steady light snow should finally come to an end by late
afternoon/early evening. Total snow accumulations of 1-3".

KBDL Terminal...Moderate confidence in TAF. Light snow ends by
lunchtime with snow accumulations of 1-2" expected.

Outlook /Monday Night through Thursday/... 

Monday Night: VFR. Breezy. Slight chance SHSN.

Tuesday: VFR. 

Tuesday Night: VFR. Breezy. 

Wednesday: VFR. Windy with areas of gusts up to 30 kt. 

Wednesday Night through Thursday: VFR. Breezy.

&&

.MARINE...
Forecaster Confidence Levels...

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

Today Through Monday Night  ...High confidence.

Light N/NW winds through the early afternoon. Winds quickly increase 
to gales around 21z and gales continue through 20z Monday. Strong 
cold advection allows for ample mixing resulting in wind gusts 
between 35-40kts Sunday evening through Monday afternoon. Areas of 
very light freezing spray possible 00z Monday - 19z Monday. 
Elsewhere, small craft advisory conditions expected in Narragansett 
Bay and Boston Harbor.

Outlook /Monday Night through Thursday/...

Monday Night: Moderate risk for Small Craft Advisory winds with
gusts up to 25 kt. Local rough seas. Slight chance of snow
showers. 

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

Tuesday Night: Low risk for Small Craft Advisory winds with
gusts up to 30 kt. Seas locally approaching 5 ft. 

Wednesday: Strong winds with gusts up to 30 kt. Areas of rough
seas. 

Wednesday Night: Low risk for Small Craft Advisory winds with
gusts up to 25 kt. Local rough seas. 

Thursday: Low risk for Small Craft Advisory winds with gusts up
to 30 kt. Areas of seas approaching 5 ft.

&&

.BOX WATCHES/WARNINGS/ADVISORIES...
CT...None.
MA...Winter Weather Advisory until 7 PM EST this evening for 
     MAZ017>024.
RI...Winter Weather Advisory until 7 PM EST this evening for 
     RIZ001>008.
MARINE...Small Craft Advisory from 4 PM this afternoon to 3 PM EST 
     Monday for ANZ230-236.
     Gale Warning from 7 PM this evening to 1 PM EST Monday for 
     ANZ231>235-237-250-251-254>256.

&&

$$

SYNOPSIS...Frank/FT
NEAR TERM...Belk/FT
SHORT TERM...FT
LONG TERM...Frank
AVIATION...Frank/FT
MARINE...Frank/FT