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 240538
AFDBOX

Area Forecast Discussion
National Weather Service Boston/Norton MA
1238 AM EST Sat Jan 24 2026

.WHAT HAS CHANGED...
Little change to the forecast. Winter Storm Warnings have been 
issued for all of southern New England since confidence is high
for heavy snow with snowfall rates as high as 1 to 2 inches per
hour during the peak of the storm Sunday night. There is still 
some uncertainty if snow mixes with or changes to sleet near the
South Coast which could limit snowfall totals somewhat there.

&&

.KEY MESSAGES...

- Dangerously cold wind chills tonight into Saturday. 

- Significant icing from freezing spray on the coastal waters 
  tonight into Saturday.

- A winter storm looks to bring a substantial accumulation of
  dry, powdery snowfall 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, and near-blizzard
  conditions could develop in short intervals.

&&

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

Arctic cold front remains on schedule to cross southern New England 
later this afternoon and early this evening. Strong cold advection 
will produce deep mixing up to 850 mb resulting in 30-40 mph gusts 
for much of the night. Temperatures dropping below zero across the 
interior and into single numbers closer to the coast will result in 
dangerous wind chills down to -25F along east slopes of Berkshires
and to -10F to -15F elsewhere, including Cape Cod and the 
Islands where we have expanded the Cold Weather Advisory. Some 
recovery in wind chills Saturday as winds slowly diminish but 
actual highs will only reach the teens, with single numbers in 
the higher elevations.


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

NW Gale force winds up to 40kt on the coastal waters combined with 
the arctic cold is expected to lead to moderate to heavy freezing 
spray tonight into Saturday. Vessels encountering heavy freezing 
spray could see dangerous ice accretion rates of 0.8"-1.6" per hour. 
The more favored areas for heavy freezing spray include the eastern 
MA waters and waters around Cape Cod and the Islands, especially 
Nantucket Sound. Light freezing spray should persist much of 
the day Saturday.


KEY MESSAGE 3...A winter storm looks to bring a substantial 
accumulation of dry, powdery snowfall 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, and near-
blizzard conditions could develop in short intervals.

A large winter storm impacting the Southern Plains, Mid-South 
and the Appalachians/Mid-Altc region tonight into Saturday 
remains poised to affect Southern New England Sunday, continuing
into Monday before tapering off Monday evening. An anomalous 
amount of deep moisture falling into an antecedent frigid, 
Arctic airmass is likely to produce a substantial accumulation 
of dry, powdery snow for much of Southern New England. With the 
700 mb trough positioned to our northwest into Upstate NY 
allowing for some intrusion of warmer air aloft from the mid-
Atlantic/waters, the potential exists for sleet to still mix in 
along the immediate south coast and the Islands. Although that 
could cut into accumulations for those locations, it's 
anticipated that warning-criteria snowfall should be met before 
that transition potentially happens and won't significantly 
affect messaging. Weighing that, Winter Storm Warnings have now 
been posted for all of Southern New England, segmented out in 
such a way that Block Island, Martha's Vineyard and Nantucket 
which have the best shot at periods of sleet with lower (7-10") 
accumulation, with all snow indicated for the large remainder of
Southern New England, with snow totals in the 12" to 17" range.
The potential exists for localized, isolated totals higher than
that could develop pending placement of heavier snowbands, 
which is still uncertain at this day- 3 timeframe. 

Overall no major changes on the synoptic scale with some subtle 
wobbles in the storm track. Besides the still-credible potential for 
sleet to mix in along the immediate south coast/the Islands, there 
has been a few other changes to take note of. Period of heaviest 
snowfall still looks to develop Sunday early evening through early 
Monday morning, where the combination of strong frontogenetic 
forcing and heaviest liquid-equivalent QPF produces bands of heavy 
snow potentially with snow rates in the 1-2" per hour neighborhood. 
Travel is likely to be very difficult to nigh-impossible during this 
period of time. However as illustrated across several model outputs, 
it now looks like a dryslot aloft sapping RH in the snow growth 
layer races ENE across the southern roughly two-thirds of Southern 
New England Monday morning - the implication being that snow 
accumulations for Monday mid-morning to Monday afternoon could be 
lighter. Models are also now showing stronger ENE wind gusts in the 
25-30 to 35-40 mph range Sunday night to early Monday with the 
strongest gusts over the Cape and Islands. That could open the door 
for areas of blowing snow to develop and this was indicated in the 
weather grids moreso along the immediate coastlines. Brief periods 
of near-blizzard conditions could be possible if stronger gusts 
materialize. The other uncertainty is the exact placement of 
mesoscale snowbands; we probably won't have a solid grasp on where 
these localized bands may develop for another day or two, but one 
area which could be favored is just west of a modeled intense 
coastal front roughly along the I-495 to I-95 corridors. Further 
adjustments to the snow forecast could be possible pending the 
extent of sleet mixing in and the location/placement of heavier 
snowbands.

Snow develops Sunday morning to early afternoon from SW to NE, 
becoming steady into Sunday afternoon. In most areas, snow will be 
falling with temperatures in the teens, which will favor a drier 
snow. As mentioned, the period of heaviest snowfall and most 
treacherous travel conditions looks to be from Sunday early evening 
to early Monday morning, with snow rates in the 1 to 2 inch per hour 
range possible. As sleet mixes in along the South Coast and the 
dryslot moves in aloft into Monday morning, we should then see 
lighter-accumulating snow for Monday/Monday afternoon before 
tapering off into Monday evening.  

Even though easterly winds are a little stronger, the risk for 
coastal flooding is minimal as astro tides are low.

&&

.AVIATION /06Z SATURDAY THROUGH WEDNESDAY/...
Forecaster Confidence Levels...

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

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 gusts
up to 30 kt. SN.

Monday Night: Mainly VFR, with local MVFR possible. Windy with
gusts up to 35 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 surges into region tonight and Saturday on Gale force
NW winds, resulting in moderate to heavy freezing spray, which
becomes lighter Saturday but should persist all day. Winds
diminish Saturday night.

Winter storm expected Sunday into Monday with poor visibility in
heavy snow and perhaps sleet on south coastal waters. NE winds
may reach SCA Sunday, but of more concern is for a period of 
Gale force W/NW 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 13 ft. Snow, rain, sleet. Visibility
1 nm or less.

Monday: Strong winds with gusts up to 35 kt. Rough seas up to
13 ft. Snow, rain likely. Visibility 1 to 3 nm.

Monday Night: Moderate risk for gale force winds with local
gusts up to 45 kt. Rough seas up to 16 ft. Chance of snow,
chance of freezing spray. Local visibility 1 to 3 nm.

Tuesday: Strong winds with gusts up to 40 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. Rough seas up to 11 ft. 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...McMinn
MARINE...McMinn