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 221831
AFDBOX

Area Forecast Discussion
National Weather Service Boston/Norton MA
131 PM EST Thu Jan 22 2026

.WHAT HAS CHANGED...
Confidence continues to increase on an arctic outbreak Friday night 
and Saturday, followed by a high impact winter storm Sunday into 
Monday. Cold weather headlines and Winter Storm Watches have been 
issued, along with Gale Warnings and Freezing Spray headlines for 
the coastal waters.

&&

.KEY MESSAGES...

- Few snow or rain showers through the evening, primarily in
  western MA.

- Dangerously cold wind chills Friday night into Saturday with heavy
  icing from freezing spray on the coastal waters.

- A winter storm has the potential to bring substantial snow
  accumulations to Southern New England Sunday through much of
  Monday. Winter Storm Watches have been issued Sunday into
  Monday evening. Travel Sunday into the Monday morning commute
  is likely to be very difficult. 

&&

.DISCUSSION...

Key Message 1...Few snow or rain showers through the evening, primarily
in western MA.

Weak front and mid level short wave was producing some light
snow showers in western New England this afternoon. These
features will weaken as they approach our area through the
evening, but we could still see some light snow or rain showers
(maybe more like flurries or sprinkles) with no impact given
temperatures are all above freezing.


Key Message 2...Dangerously cold wind chills Friday night into 
Saturday with heavy icing from freezing spray on the coastal 
waters.

Arctic front still on schedule to cross southern New England Friday 
afternoon. It's possible we see a few snow or rain showers ahead of 
it during the day, especially in western New England, but for the 
most part it will come through dry.

Behind front, our well advertised shot of arctic air arrives on 
strong NW winds Fri night with core of coldest air passing over us 
on Saturday. Both 850 mb and 925 mb temps bottom out at -20C to -25C 
across southern New England which is anomalously cold (-2 to -3
standard deviations) and deep mixing will bring gusts of 35- 
45 MPH per model soundings. We've converted the Extreme Cold 
Watch along east slopes of Berkshires to an Extreme Cold Warning
for wind chills as low as -25F Friday night into Saturday, and 
we've issued a Cold Weather Advisory elsewhere (except for Cape 
Cod and Islands) for wind chills as low as -15F. Actual air 
temperatures will drop into the single numbers Friday night and 
only recover into the teens Saturday afternoon, possibly staying
just below 10 degrees in the higher elevations. 

On the coastal waters Gale force winds of up to 40kt offshore, 
combined with the arctic cold, is expected to lead to moderate 
or even heavy freezing spray Friday night into Saturday, 
resulting in dangerous icing for vessels at sea. The areas of 
greatest concern for heavy icing is on E MA waters including 
Nantucket Sound. Light freezing spray should persist much of the
day Saturday.


Key Message 3...- A winter storm has the potential to bring substantial
snow accumulations to Southern New England Sunday through much 
of Monday. Winter Storm Watches have been issued Sunday into 
Monday evening. Travel Sunday into the Monday morning commute is
likely to be very difficult. 

A potent winter storm moving through the Southern Plains, Mid-South 
and the Appalachians/Mid-Atlc states late this week/early this 
weekend is poised to affect Southern New England Sunday, continuing 
into a good portion of Monday. This system is expected to carry with 
it a copious amount of moisture from the Gulf and the southeast 
Pacific - which leads to a large amount of liquid-equivalent 
precipitation, much of if not all of which will be falling into an 
antecedent, although modifying, frigid Arctic airmass. And much of 
if not all of precipitation is expected to fall as snow, although 
there are some model-forecast outcomes which show an injection of 
above-freezing air aloft which could tilt some areas over to sleet. 

There were overall no substantial change in the forecast guidance 
compared to previous forecasts; and it looks as though the storm's 
track seems anticipated to pass eastward from the mid-Atlantic near 
40N/70W. Although this is a favorable track for accumulating snow in 
the I-95 corridor, the deeper moisture associated with this system 
looks to generate a large precipitation shield. There are still 
plenty of uncertainties that need to be ironed out specific to the 
accumulations. One is the potential for heavier mesoscale banding 
and the placement of those snowbands, which are still uncertain at 
this Day-4 to Day-5 range. There is also the possible development of 
a warm nose aloft, solutions offered by the ECMWF and Canadian-GEM 
and their ensembles, which could force some areas over to sleet for 
a time Sunday night or into Monday and that could cut into 
accumulations. The greatest risk for this appears to be in southeast 
New England, potentially as far north as the I-95 corridor. Finally, 
it isn't clear how long snow may last, with the potential for wrap-
around bands of snow lingering into Monday mainly in interior 
Southern New England along/north and west of I-95. 

We continue to take a probabilistic approach weighing the above 
uncertainties. That being said, continued high probabilities of over 
6 inches of snow and moderate probabilities of over 12 inches of 
snow led to issuance of a Winter Storm Watch for all of Southern New 
England. We are messaging the potential for snow totals in the 6 to 
12 inch range being common, with the potential for over 12 inches in 
some locations. This could be a conservative best estimate and 
additional changes are likely, and there are still some forecasts 
which are quite a bit higher than what is stated in the Winter Storm 
Watch. Although in light of the above uncertainties, it seems 
prudent to continue to watch trends. 

Snow looks to begin Sunday morning, quickly becoming heavy Sunday 
afternoon into at least Monday morning, and while snow intensity may 
ease up some into Monday for eastern/southeast New England, the 
potential for snowbands dropping additional moderate to heavy snows 
may continue into Monday. Travel is likely to become very difficult 
and treacherous, especially for overnight and continuing through the 
Monday morning commute. 

Fortunately the chances of enhanced winds with this system and its 
passage Monday evening are low. That should help with recovery, but 
it remains quite cold behind this system, so the snow is likely to 
stick around into next week.

&&

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

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

18Z TAFs: High confidence.

VFR. SW winds gust to 25kt through late afternoon, then diminish
to 5-15kt tonight. W/SW winds Fri increase during the morning
with 20-30kt gusts, then shift to NW later in the day with
25-35kt gusts into Fri night.

KBOS Terminal...High Confidence in TAF. 

KBDL Terminal...High Confidence in TAF.

Outlook /Friday Night through Monday/...

Friday Night: VFR. Windy with gusts up to 30 kt. 

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

Saturday Night: VFR. Breezy. Slight chance SN.

Sunday: MVFR/IFR conditions possible. Breezy. SN.

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

Monday: Mainly VFR, with areas IFR possible. Breezy. Chance SN.

&&

.MARINE...
Forecaster Confidence Levels...

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

High confidence through the weekend.

Main concern as outlined above is for Gale force NW winds and
moderate to heavy freezing spray Fri night and Sat as arctic air
surges into southern New England. Prior to that, gusty W/SW
winds will persist through Fri with gusts of 25-30kt at times on
coastal waters.

Concerning winter storm for Sun into Mon, not looking at strong
winds until the storm passes to our east later Mon with
potential SCA winds and seas, perhaps Gales on outer waters. 
Certainly looking at likelihood of heavy snow with poor 
visibility, although there could be mixing with sleet or even 
rain on south coastal waters.

Outlook /Friday Night through Monday/...

Friday Night: Strong winds with gusts up to 35 kt. Areas of
rough seas. Freezing spray, slight chance of snow. 

Saturday: Moderate risk for Small Craft Advisory winds with
gusts up to 30 kt. Areas of rough seas. Freezing spray. 

Saturday Night: Winds less than 25 kt. Areas of seas
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, chance of
freezing spray. Visibility 1 nm or less.

Sunday Night: Strong winds with gusts up to 35 kt. Seas up to
5 ft. Snow, chance of freezing spray. Visibility 1 nm or less.

Monday: Moderate risk for Small Craft Advisory winds with gusts
up to 30 kt. Seas up to 5 ft. Chance of snow, chance of
freezing spray. Local visibility 1 nm or less.

&&

.BOX WATCHES/WARNINGS/ADVISORIES...
CT...Cold Weather Advisory from 10 PM Friday 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 Friday to 10 AM EST Saturday 
     for MAZ003>007-010>021-026.
     Winter Storm Watch from Sunday morning through Monday evening 
     for MAZ002>024-026.
     Extreme Cold Warning from 7 PM Friday to 1 PM EST Saturday for 
     MAZ002-008-009.
RI...Cold Weather Advisory from 10 PM Friday to 10 AM EST Saturday 
     for RIZ001>007.
     Winter Storm Watch from Sunday morning through Monday evening 
     for RIZ001>008.
MARINE...Gale Warning from 1 PM Friday to 7 AM EST Saturday for 
     ANZ230>237-250-251-254>256.
     Freezing Spray Advisory from 10 PM Friday to 4 PM EST Saturday 
     for ANZ230-233>235-237-256.
     Heavy Freezing Spray Warning from 10 PM Friday to 1 PM EST 
     Saturday for ANZ231-232-250-251-254-255.

&&

$$

DISCUSSION...Loconto/JWD
AVIATION...JWD
MARINE...Loconto/JWD