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 241854
AFDBOX

Area Forecast Discussion
National Weather Service Boston/Norton MA
154 PM EST Sat Jan 24 2026

.WHAT HAS CHANGED...

- Trended snowfall totals lower for the south coast of Rhode 
  Island and south coast of Massachusetts. This does include the
  Cape and Islands, due to the threat of snow turning to sleet,
  which will lower totals. 

- Freezing Spray Advisory issued for lingering moderate freezing
  spray on eastern MA waters through this evening.

- Gale Warnings issued for increasing NW winds to 40kt on
  coastal waters behind storm Sunday night into Monday.

&&

.KEY MESSAGES...

- Coastal storm will bring heavy snow to Southern New England
  Sunday into Monday. Heavy snow with 1-2"+ inch per hour snow
  rates Sunday afternoon and evening, making travel treacherous.
  Waning snow Monday followed by colder temperatures.

- Freezing spray lingers into the evening followed by another
  round of Gale force winds Sunday night into Monday.

- Cold and mainly dry this week but watching the possibility of
  another coastal low sometime later in the week.

&&

.DISCUSSION...

Key Message 1...

Quiet, very cold temperatures, and gusty conditions this afternoon as 
final preparations are made ahead of an impactful widespread winter 
storm, set to begin in less than 24-hours. 

A major winter storm will bring widespread snowfall across all of
southern New England Sunday into Sunday night, leading to dangerous
travel by Sunday afternoon and through the night. Intense snowfall
rates of 1-2" per hour will accumulate widespread 12-18" across most
of southern New England, with 8-12" across the immediate south coast,
Cape Cod, and Islands due to the transition from snow to sleet.


A dynamic winter storm moving out of the southern states will tap
into rich moisture from the Gulf and transport it north on Sunday.
Model guidance over the past 12-24 hours shows less than ideal 
conditions for a full out high-end snow event. Nevertheless there
is plenty of snow to go around. The upper- level pattern shows the
700mb wave never closes off and the 850mb low tracking either over
southern New England or just north (depending on your flavor of
guidance). The surface low pressure tracks inside of the benchmark
and remains somewhat weak, with pressure ~1000mb. What we have 
working in our favor, the Arctic air mass, moisture plume with 
PWATs 2-3 standard deviations above climo, and strong frontogenesis.
In addition, a coastal front develops, this mesoscale features may
lead to isolated heavier bursts and subsequent totals of snow. 
High-res guidance is picking up on the feature Sunday afternoon 
into the evening. Essentially this front is a dividing line 
between Arctic air and "seasonable" cold air. Along and west of 
this front, there is potential for enhanced snow amounts. With 
this setup, a front end thump is likely, with snowfall rates on 
the order of 1-2" per hour, though cannot rule out instances of 
3" per hour between 3 PM and 9 PM. These intense rates arrive to
SW CT between 3-5 PM then reaching NE MA by 7-9 PM. During this
time, it is not advisable to travel, unless absolutely necessary
as whiteout conditions are likely given the intensity of the 
snowfall rates. 

And given how dynamic the system is, thundersnow is a possibility, 
cue the excitement! It's also worth a mention, the HREF shows low 
probabilites (less than a 30/40 percent chance) of coastal area to 
reach blizzard criteria. While winds are expected to become gusty, 
feel that gusts will fall shy of criteria from the east-northeast 
around 30 mph. Don't feel it will become the dominate feature, thus 
have held off on an upgrades to the winter weather headlines. Either 
way, travel during this time will be treacherous. 

As the storm wanes, warm air becomes introduced aloft, transition 
from snow to sleet across southeast MA and southern RI. However, 
there is lower confidence in how far north/inland the sleet reaches. 
Current thought are areas to the south of a line from Willimantic, 
to Warwick, to Taunton have the greatest potential for sleet, which 
has lowered expected snow totals, as mentioned above. There is even 
potential for sleet to change to rain on the island of Nantucket, 
which would compress the snowpack, leading to a dense snow and make 
it look like "less" snow fell. Snow continues overnight and wanes on 
Monday, this is associated with a weak surface low pressure off 
shore, flipping the wind from onshore to the north-northwest with 
additional minor snow accumulation. And the current snowfall map 
issued encompasses all snowfall from Sunday through Monday afternoon. 
Snow wraps up from west to east, starting first in western areas 
late Monday morning, eastern areas by the coast are later in the 
day, later afternoon to early evening. 

By Monday night much drier air return and snow ceases. Temperatures 
Monday night falls to the single digits. 


Key Message 2...Freezing spray lingers into the evening followed
by another round of Gale force winds Sunday night into Monday.

Still seeing buoy reports of moderate freezing spray on E MA
waters including Nantucket Sound so we maintained the Freezing
Spray Advisory until this evening for these waters. 

Issued Gale Warnings for increasing NW winds to 40kt as the
storm departs later Sunday night into Monday. May also see some
additional light freezing spray during this time as another
surge of colder air works into region.


Key Message 3...Cold and mainly dry this week but watching the 
possibility of another coastal low sometime later in the week.

Mainly dry but cold NW flow is expected to persist much of next
week and some weak disturbances aloft could bring some flurries
from time to time, as well as at least some light freezing spray
on the coastal waters. Longer range ensembles show the 
potential for another southern stream low pressure system to 
move off the East Coast later in the week or perhaps even next 
weekend, but for now, it's equally possible that any system 
tracks well offshore.

&&

.AVIATION /18Z SATURDAY THROUGH THURSDAY/...
Forecaster Confidence Levels...

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

18Z Update: High confidence.

VFR through tonight as NW winds diminish by late afternoon and
veer to N/NE overnight. Light snow begins in western New England
13z-15z and 15z-17z farther east which brings a rapid drop to
IFR conditions. Expecting heavy snow to arrive within 1-3 hours
of onset with widespread LIFR conditions later Sunday afternoon
and the first part of Sunday night. Snowfall rates of 1-3" per
hour are likely. Snow lessens in intensity overnight into 
Monday but there should be a change to rain for a time on the 
Islands and possibly Cape Cod, with some sleet possible along 
the South Coast.

Snowfall totals by Monday morning should range from 6-12" along
the South Coast, Cape Cod, and Islands to 12-18" elsewhere. Much
of this will fall from later Sunday afternoon through midnight
Monday.

KBOS Terminal...High Confidence in TAF. Forecast is for 16" of 
snow at Logan Airport.

KBDL Terminal...High Confidence in TAF. Forecast is for 15" of
snow at Bradley Airport.

Outlook /Monday through Thursday/...

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

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

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

Tuesday Night through Wednesday: VFR. Breezy. 

Wednesday Night: VFR. 

Thursday: VFR. Breezy. Slight chance SN.

&&

.MARINE...
Forecaster Confidence Levels...

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

High confidence through early next week.

NW winds diminish quickly tonight and turn NE Sunday ahead of 
the coastal low pressure system heading up the coast. Snow 
arrives by early afternoon and quickly becomes heavy at times, 
before changing to rain or sleet on most of south coastal waters
Sunday night. 

Outlook /Monday through Thursday/...

Monday: Moderate risk for Small Craft Advisory winds with gusts
up to 30 kt. Rough seas up to 13 ft. Rain likely, freezing
spray, chance of snow, freezing rain likely. Local visibility
1 nm or less.

Monday Night: Strong winds with gusts up to 40 kt. Rough seas
up to 14 ft. Chance of snow, chance of freezing spray, chance
of freezing rain. Local visibility 1 to 3 nm.

Tuesday: Strong winds with gusts up to 35 kt. Rough seas up to
13 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. Seas up to 5 ft. Chance of freezing spray. 

Wednesday Night: Winds less than 25 kt. Areas of seas
approaching 5 ft. Chance of freezing spray. 

Thursday: Winds less than 25 kt. Seas locally approaching 5 ft.
Chance of freezing spray, slight chance of snow. 

&&

.BOX WATCHES/WARNINGS/ADVISORIES...
CT...Winter Storm Warning from 7 AM Sunday to 8 PM EST Monday for 
     CTZ002>004.
MA...Winter Storm Warning from 7 AM Sunday to 8 PM EST Monday for 
     MAZ002>024-026.
RI...Winter Storm Warning from 7 AM Sunday to 8 PM EST Monday for 
     RIZ001>008.
MARINE...Gale Warning from 10 PM Sunday to 5 AM EST Monday for ANZ230-
     236.
     Freezing Spray Advisory until 7 PM EST this evening for ANZ231-
     232-250-251-254-255.
     Gale Warning from 10 PM Sunday to 6 AM EST Monday for ANZ231.
     Gale Warning from 7 PM Sunday to 6 AM EST Monday for 
     ANZ232>234.
     Gale Warning from 6 PM Sunday to 6 AM EST Monday for ANZ235-
     237.
     Gale Warning from 10 PM Sunday to 7 AM EST Monday for ANZ250-
     251.
     Gale Warning from 7 PM Sunday to 7 AM EST Monday for ANZ254.
     Gale Warning from 4 PM Sunday to 7 AM EST Monday for ANZ255-
     256.

&&

$$

DISCUSSION...Dooley/JWD
AVIATION...JWD
MARINE...JWD