Old Res Weather

Lexington, Massachusetts, USA

35°F

2/16/2025 7:17pm

Lexington Conditions: Light snow, Overcast
Temperature: 35.1°F / 1.7°C
Dew Point: 32.4°F
Relative Humidity: 90%
Wind: Calm, 10-min avg: Calm, gust: None
Barometer: 29.00 in Falling Slowly
Visibility: 3 miles
Rain Today: 0.01 in
UV Index: $VPuv None

Area Forecast Discussion
for Boston / Norton, MA

        
000
FXUS61 KBOX 231644
AFDBOX

Area Forecast Discussion
National Weather Service Boston/Norton MA
1144 AM EST Fri Jan 23 2026

.WHAT HAS CHANGED...
The forecast remains on track, with minimal changes since the 
previous update.

&&

.KEY MESSAGES...

- Dangerously cold wind chills tonight into Saturday. 

- Significant icing possible from freezing spray on the coastal 
waters.

- A late- weekend coastal storm will bring high impact snow to
  Southern New England Sunday into Monday.

&&

.DISCUSSION...
Key message 1...Dangerously cold wind chills tonight into 
Saturday.

Continue to expect an arctic front passing through southern New 
England later this afternoon. Hi-res guidance continues to indicate 
850 mb and 925 mb temps tanking to -23C to -27C across southern New 
England Saturday morning. Deep mixing to near 850mb will bring gusts 
of 30-40 mph to the surface through the night. Prolonged gusty winds 
in combination with already frigid temperatures in the single digits 
after sunset will bring wind chills as low as -25F tonight into 
Saturday in the eastern slopes of the Berkshires, -15F everywhere 
else (except -10F for Cape Cod and Islands). Temperatures Saturday 
will struggle to improve, with highs expected in the low to mid 
teens... except single digits in the high elevations.

Key Message 2...Significant icing possible from freezing spray 
on the coastal waters.

Gale force winds of up to 40kt over the coastal waters combined with 
the arctic cold is expected to lead to moderate, possibly even 
heavy, freezing spray tonight into Saturday. Vessels encountering 
heavy freezing spray could see ice accretion rates of 0.8"-1.6" per 
hour. The possibility for heaviest freezing spray is expected along 
the southern and easter waters, particularly within Nantucket Sound.
Light freezing spray should persist much of the day Saturday.

Key Message 3...A late- weekend coastal storm will bring high impact 
snow to Southern New England Sunday into Monday.

A major storm that will bring winter weather stretching from the 
southern plains through the southeast then reaches New England by 
Sunday. A Winter Storm Watch remains in effect for all of SNE for 
significant snow potential. The system moving out of the plains will 
direct a plume of deep moisture and warm air into/over top of a dome 
of subfreezing air associated with a sprawling high pressure over 
the northeast which will lead to a prolonged period of snowfall, 
some of it heavy. We have the necessary ingredients with a very cold 
antecedent airmass, plume of subtropical moisture, and strong warm 
advection/frontogenetical forcing. Most recent (00z) runs of 
deterministic guidance crucially keep a low track near the 70/40 
benchmark (no wholesale shifts) but its still better to focus on 
ensemble guidance which, depending on the model, indicates varying 
degrees of spread remaining. This is one factor that would lead us 
to be cautious in declaring exact snowfall amounts as the track is a 
factor. Another related factor is the presence/strength of a 700 mb 
warm nose which could lead to a period of mixed precipitation on the 
south coast overnight, potentially up into the south shore of 
eastern MA and northern RI. 

We are just beginning to get into the reach of some high 
-resolution guidance which will shed more light on this, among 
other details, so check back periodically for updated snow 
forecast maps. Confidence in the onset time is moderate to high,
with snow moving in Sunday morning into early afternoon. Some 
locations will have stronger omega within the DGZ than others 
(this means bigger dendrites/higher snowfall rates) but where 
the heaviest bands will set up and when remains uncertain. What 
is better known is that the period of heaviest snow should be 
Sunday evening through the first half of the overnight. The low 
then pulls east and we'll see lighter wrap-around moisture in 
the form of light snow continue into the day on Monday. At the 
moment the most likely snowfall totals are in the 8-14 inch 
range. Whatever snow does fall isn't going anywhere fast as a 
cold airmass remains entrenched over the northeast next week 
(highs in the teens and 20s).

&&

.AVIATION /18Z FRIDAY THROUGH WEDNESDAY/...
Forecaster Confidence Levels...

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

18Z Update: High confidence.

VFR. Arctic cold front crosses southern New England 21z-00z with
wind shift to NW and increasing winds of 15-25kt with gusts to
30-35kt which persists through most of the night. NW winds
gradually subside Sat but 20-25kt gusts should continue through
midday.

KBOS Terminal...High Confidence in TAF. 

KBDL Terminal...High Confidence in TAF.

Outlook /Saturday Night through Tuesday/...

Saturday Night: VFR. Breezy. 

Sunday: Mainly VFR, with areas IFR possible. Windy with local
gusts up to 30 kt. SN.

Sunday Night: Mainly IFR, with local MVFR possible. Windy with
gusts up to 35 kt. SN.

Monday: Mainly IFR, with local MVFR possible. Windy with local
gusts up to 30 kt. SN.

Monday Night: Mainly VFR, with local IFR possible. Windy with
gusts up to 35 kt. Chance SN.

Tuesday: VFR. Windy with local gusts up to 30 kt. 

&&

.MARINE...
Forecaster Confidence Levels...

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

High confidence through the weekend.

Northwesterly gale force winds up to 40kts contribute to heavy 
freezing spray tonight into Saturday with the passage of an arctic 
front. Seas on the outer waters 5-7 ft this morning build throughout 
today to 7-10 ft while the inner, coastal waters remain 3-5 ft.

Expecting winds to diminish Saturday evening and remain below SCA 
levels with the arrival of snow.

Outlook /Saturday Night through Tuesday/...

Saturday Night: Winds less than 25 kt. Seas locally approaching
5 ft. Slight chance of snow. 

Sunday: Low risk for Small Craft Advisory winds with gusts up
to 30 kt. Seas locally approaching 5 ft. Snow. Visibility 1 nm
or less.

Sunday Night: gale force winds with gusts up to 40 kt. Areas of
rough seas. Snow, rain, sleet. Visibility 1 nm or less.

Monday: Strong winds with gusts up to 35 kt. Rough seas up to
12 ft. Snow. Visibility 1 to 3 nm.

Monday Night: gale force winds with local gusts up to 45 kt.
Rough seas up to 13 ft. Chance of snow. Areas of visibility
1 nm or less.

Tuesday: Strong winds with gusts up to 35 kt. Rough seas up to
12 ft. Chance of freezing spray, slight chance of snow. 

&&

.BOX WATCHES/WARNINGS/ADVISORIES...
CT...Cold Weather Advisory from 10 PM this evening to 10 AM EST 
     Saturday for CTZ002>004.
     Winter Storm Watch from Sunday morning through Monday evening 
     for CTZ002>004.
MA...Cold Weather Advisory from 10 PM this evening to 10 AM EST 
     Saturday for MAZ003>007-010>024-026.
     Winter Storm Watch from Sunday morning through Monday evening 
     for MAZ002>024-026.
     Extreme Cold Warning from 7 PM this evening to 1 PM EST 
     Saturday for MAZ002-008-009.
RI...Cold Weather Advisory from 10 PM this evening to 10 AM EST 
     Saturday for RIZ001>008.
     Winter Storm Watch from Sunday morning through Monday evening 
     for RIZ001>008.
MARINE...Gale Warning until 7 AM EST Saturday for ANZ230>237-250-251-
     254>256.
     Freezing Spray Advisory from 10 PM this evening to 4 PM EST 
     Saturday for ANZ230-233>237-256.
     Heavy Freezing Spray Warning from 10 PM this evening to 1 PM 
     EST Saturday for ANZ231-232-250-251-254-255.

&&

$$

DISCUSSION...BW/McMinn
AVIATION...JWD
MARINE...BW/McMinn