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: 1½ miles
Rain Today: 0.01 in
UV Index: $VPuv None

Area Forecast Discussion
for Boston / Norton, MA

        
000
FXUS61 KBOX 241040
AFDBOX

Area Forecast Discussion
National Weather Service Boston/Norton MA
540 AM EST Sat Jan 24 2026

.WHAT HAS CHANGED...
The forecast remains on track, with minimal changes to Sunday's 
snowstorm.

&&

.KEY MESSAGES...

- Dangerously cold wind chills linger through Saturday. 

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

- A coastal storm will bring heavy snow to Southern New England 
Sunday into Monday. Heavy snow with 1"+  inch per hour snow rates 
Sunday early evening to early Monday morning will make travel very 
difficult. Increasing easterly  winds could produce areas of blowing 
snow.

- Cold and mostly dry mid week then there is potential for some
  unsettled weather the latter half of the week.

&&

.DISCUSSION...
Key message 1...Dangerously cold wind chills linger through 
Saturday.

The arctic front has now passed through southern New England, 
bringing gusty winds and plummeting temperatures. 00z soundings from 
OKX and ALY show 850mb temperatures of -11C and -21C, and expecting 
temperatures aloft to continue falling to -25C to -27C throughout 
the night and into the 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 surface temperatures in the 
negatives to low single digits will bring wind chills as low as 
-25F in the eastern slopes of the Berkshires and -10F to -15F 
everywhere else. 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.

Northwesterly 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 through 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 coastal storm will bring heavy snow to Southern 
New England Sunday into Monday. Heavy snow with 1"+  inch per hour 
snow rates Sunday early evening to early Monday morning will make 
travel very difficult. Increasing easterly  winds could produce 
areas of blowing snow.

Guidance continued to hold steady overnight with no significant 
changes to thinking with regard to our upcoming snowstorm. This 
major storm, the largest we've experienced in several years, 
originates as a multifaceted winter storm over the southern Plains 
and southeast U.S. later today. The plume of subtropical moisture 
will then move up through the mid-Atlantic and into New England on 
Sunday. As it does, strong warm advection will encounter the dome of 
arctic air currently overhead and be lifted, squeezing out copious 
amounts of moisture in the form of snow. All the ingredients for 
heavy snow are there, with a very cold antecedent airmass, plume of 
subtropical moisture, and strong warm advection/frontogenetical 
forcing in the low/mid levels. Models indicate a very strong band of 
frontogenesis at 700mb and 850 mb lifting north Sunday afternoon 
while BUFKIT soundings show a period of strong omega within the -12 
to -18F dendritic growth zone. Together with the anomalous moisture 
present this will result in a period of snowfall rates 1-2 inches 
Sunday afternoon through around midnight for various parts of SNE. 
After midnight a dry slot moves overhead desaturating the DGZ so 
snow is expected to become lighter (with smaller dendrites), 
continuing through the day on Monday as moisture wraps around the 
exiting low. Given the strong forcing in the DGZ and the cold 
temperatures, expecting very fluffy snow during the bulk of the 
event. This will lead to very hazardous driving conditions centered 
around Sunday evening/early overnight. Generally expecting 13-18 
inches of snow for most, with some locations especially in eastern 
MA and the Berkshires seeing localized amounts closer to 20 inches 
thanks to ocean and orographic enhancement respectively. We also 
have to watch for some mesoscale banding which is where we'd more 
likely see these higher totals. These bands tend to set up NW of the 
frontogenesis maxima, so this would suggest somewhere in the central 
MA region. Also a coastal front over southeast MA could also make 
that area favorable. It is next to impossible to nail the exact 
placement of these with much lead time. 

We continue to see signs of a 700 mb warm nose moving up into the 
south coast during the early overnight hours, which may cause some 
sleet to mix in and bring down totals in RI and southeast MA. 
Regardless, though, highly impactful snow is expected everywhere. 

Finally, while we're not expecting a big power outage risk from this 
system thanks to the fluffy nature of the snow and the lack of 
damaging wind gusts, winds will still be quite gusty. 30-40 mph 
gusts Sunday evening could lead to some localized blowing snow and 
reduced visibility for a time. 


Key Message 4...Cold and mostly dry mid week then there is potential 
for some unsettled weather the latter half of the week. 

The snow isn't going anywhere fast as the subfreezing airmass sits 
overhead well into next week thanks to a lingering mid level trough. 
Expecting dry NW flow through at least Wednesday before our next 
disturbance rounds the base of the trough bringing precipitation 
chances back to the forecast around Thursday.

&&

.AVIATION /12Z SATURDAY THROUGH WEDNESDAY/...
Forecaster Confidence Levels...

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

12Z update...

Today and Tonight: High Confidence.

VFR. Northwesterly winds 15-25kt with gusts 25-35kt persist 
into the morning. Winds gradually subside today, but 20-25kt 
gusts should continue through midday. Winds diminish to 5-10kt
this evening.

KBOS Terminal...High Confidence in TAF. 

KBDL Terminal...High Confidence in TAF.

Outlook /Sunday Night through Wednesday/...

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

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

Monday Night: Mainly VFR, with local MVFR possible. Windy with
areas of gusts up to 30 kt. Chance SN.

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

Tuesday Night through Wednesday: VFR. Breezy.

&&

.MARINE...
Forecaster Confidence Levels...

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

High confidence through the weekend.

Arctic air arrives into Saturday morning along with northwesterly 
Gale force winds, resulting in moderate to heavy freezing spray. 
Freezing spray will become lighter throughout Saturday afternoon, 
but should still persist all day. Winds diminish Saturday night.

A winter storm arrives Sunday into Monday with poor visibility 
during heavy snow. Sleet may mix into the snow at some point in the 
later half of the storm over south coastal waters. Northeasterly 
winds may reach SCA Sunday, but of more concern is for a period of 
Gale force west-northwesterly winds behind storm later Sunday night 
into Monday.

Outlook /Sunday Night through Wednesday/...

Sunday Night: Moderate risk for gale force winds with gusts up
to 40 kt. Rough seas up to 12 ft. Snow, rain, sleet. Visibility
1 nm or less.

Monday: Moderate risk for Small Craft Advisory winds with gusts
up to 30 kt. Rough seas up to 13 ft. Snow, rain likely.
Visibility 1 to 3 nm.

Monday Night: Strong winds with gusts up to 40 kt. Rough seas
up to 15 ft. Chance of snow, chance of freezing spray. Areas of
visibility 1 to 3 nm.

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

Tuesday Night: Moderate risk for Small Craft Advisory winds
with gusts up to 30 kt. Areas of rough seas. Chance of freezing
spray, slight chance of snow. 

Wednesday: Low risk for Small Craft Advisory winds with gusts
up to 25 kt. Local rough seas. Chance of freezing spray.

&&

.BOX WATCHES/WARNINGS/ADVISORIES...
CT...Cold Weather Advisory until 10 AM EST this morning for 
     CTZ002>004.
     Winter Storm Warning from 7 AM Sunday to 8 PM EST Monday for 
     CTZ002>004.
MA...Cold Weather Advisory until 10 AM EST this morning for 
     MAZ003>007-010>024-026.
     Winter Storm Warning from 7 AM Sunday to 8 PM EST Monday for 
     MAZ002>024-026.
     Extreme Cold Warning until 1 PM EST this afternoon for MAZ002-
     008-009.
RI...Cold Weather Advisory until 10 AM EST this morning for 
     RIZ001>008.
     Winter Storm Warning from 7 AM Sunday to 8 PM EST Monday for 
     RIZ001>008.
MARINE...Gale Warning until 7 AM EST this morning for ANZ230>237-250-
     251-254>256.
     Freezing Spray Advisory until 4 PM EST this afternoon for 
     ANZ230-233>237-256.
     Gale Watch from Sunday afternoon through Monday afternoon for 
     ANZ230>237-250-251-254>256.
     Heavy Freezing Spray Warning until 1 PM EST this afternoon for 
     ANZ231-232-250-251-254-255.

&&

$$

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