Old Res Weather

Lexington, Massachusetts, USA

35°F

2/16/2025 7:17pm

Lexington Conditions: Light rain, Mostly cloudy
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: 10 miles
Rain Today: 0.01 in
UV Index: $VPuv None

Area Forecast Discussion
for Boston / Norton, MA

        
000
FXUS61 KBOX 172343
AFDBOX

Area Forecast Discussion
National Weather Service Boston/Norton MA
743 PM EDT Wed Jun 17 2026

.WHAT HAS CHANGED...

Chance for severe weather continues to be present for Thursday
afternoon and evening. Damaging winds and an isolated tornado
are possible.

&&

.KEY MESSAGES...

- Gusty southerly winds with some showers and perhaps a few
  afternoon thunderstorms Thursday. Main threat for severe
  weather still looks to be to our west and south but is
  possible across SNE. 

- Beautiful weather Fri into the weekend despite gusty west winds 
  Fri-Sat. Highs mainly between 75 and 85 with low humidity.

- Potential for a much needed soaking rain to kick off the start of 
  the next work week...But that is not set in stone.

&&

.DISCUSSION...

KEY MESSAGE 1...Gusty southerly winds with some showers and perhaps 
a few afternoon thunderstorms Thursday. Main threat for severe 
weather still looks to be to our west and south but is possible 
across SNE. 

After a mostly dry day Wednesday save for some isolated showers over 
western/central MA our next impactful bout of weather arrives 
overnight and Thursday. In the mid-levels a positively tilted trough 
digs into the eastern Great Lakes early Thursday moving then over 
New England later Thursday into Friday. This directs a plume of deep 
moisture and strong low to mid level winds overhead. A strong W/SW 
jet stretches from 850mb (50-60kts) to 500mb (80-95kts) contributing 
to some very strong wind shear values. 0-6km bulk shear values are 
on the order of 70-80kts with even more impressive low level shear 
values (0-1km SRH 300-400m2s2). The limiting factor for severe 
thunderstorm development will be (potentially) very marginal 
instability. The previously mentioned LLJ will act on an early 
morning warm front to bring a round of widespread showers and 
potentially some embedded thunderstorms after midnight through mid 
to late morning. These showers and associated lingering cloudcover 
will act to limit heating and destabilization for some time. Much 
will depend on if we get many breaks in the clouds in which highs 
initially expected in the 70s could jump up coincident with higher 
instability values. At the moment, thinking that the true warm 
sector/highest instability values, and greatest severe potential 
remains just to our south and west. However, it won't take much for 
such a borderline atmospheric setup to become much more volatile. 
Historically even low instability environments have been able to be 
overcome by particularly strong shear, so a Slight Risk (level 2 of 
5) of severe weather remains in effect. The greatest threat would be 
from damaging winds, then tornado potential given the extreme low 
level shear values. For SNE, the most likely intersection of 
instability and strong shear (aka greatest severe threat) would be 
western MA and western CT during the mid afternoon to early evening. 
In sum, low confidence that severe weather materializes but high 
potential impact if it does. Timing is generally noon to 9pm 
(earlier west, later east). 

Finally, regardless, Thursday will be gusty thanks to the strong LLJ 
overhead. Much will depend on amount of clearing and resultant 
diurnal heating as to how well the BL mixes, but BUFKIT soundings 
indicate potential for wind gusts of 25 to 35 mph, even up to 40 
mph at times. 

KEY MESSAGE 2...Beautiful weather Fri into the weekend despite gusty 
west winds Fri-Sat. Highs mainly between 75 and 85 with comfortable 
humidity.

A beautiful post-frontal airmass works into southern New England Fri 
and Sat. Low pressure tracking from Quebec into the Canadian 
Maritimes will result in gusty west winds of 25 to 35 mph Fri/Sat 
afternoons with perhaps even a few spots briefly gusting up to 40 
mph. Winds should be a bit less on Sunday as the pressure gradient 
weakens.

Otherwise...beautiful weather expected Fri into the weekend with 
highs generally between 75 and 85 degrees and low humidity. Low 
temps will be pleasant too...mainly in the 50s to the lower 60s. 

The weather will be dry for all intensive purposes. Some moisture 
starved northern stream energy may trigger a brief diurnally driven 
spot shower or two this weekend. But again it is pretty much a 
beautiful dry stretch of weather into the weekend.

KEY MESSAGE 3...Potential for a much needed soaking rain to 
kick off the start of the next work week...But that is not set 
in stone.

The potential continues for a much needed soaking rain to kick off 
the start of the next work week...But that will depend upon the 
track of low pressure. This still remains uncertain given these 
tracks are usually impacted by convective processes this time of 
year. Limited baroclinicity during the summer can also result in 
more difficulties...Not to mention we are still 5 days out in the 
future. Certainly the potential remains for a soaking rainfall and 
some of our guidance continues to indicate that potential...But 
whether or not that comes into fruition remains uncertain. 

Drier and very pleasant summerlike weather should return Tue into 
Wed as high pressure builds in from the west. Temperatures look to 
be rather seasonable with comfortable humidity by the middle of next 
week.

&&

.AVIATION /00Z THURSDAY THROUGH MONDAY/...

Forecaster Confidence Levels...

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

00z TAF Update...

Tonight...High Confidence.

Mainly VFR for most of tonight...But some scattered showers 
along with localized MVFR conditions will be possible across the
interior after 08z/09z. S winds generally 10 knots or less. 

Thursday...Moderate confidence.

A period of MVFR with even localized IFR conditions possible Thu
morning with a round of showers. While a few showers possible
anywhere Thu morning...the focus for them will likely be
northwest of I-95 and especially across interior MA. The main
threat for scattered showers and t-storms will be Thu
afternoon/early evening ahead of the cold front. A few strong to
severe thunderstorms are possible too...But that will depend on
how much instability is generated ahead of the front. 

A strong LLJ will result in southerly wind gusts of 25 to 35
knots developing by afternoon with a few gusts perhaps near 40
knots. Localized/brief stronger winds possible if any severe
thunderstorms develop. 

Thursday night...High confidence. 

Any lingering SHRA/TSRA should depart the coast early-mid Thu 
evening with conditions quickly improving to VFR. Lower
cigs/vsbys may linger until midnight or so for parts of the 
Cape and Islands. SW winds 7-15 knots shift to the W overnight.

KBOS Terminal...Moderate confidence in TAF. 
 
KBDL Terminal...Moderate confidence in TAF.

Outlook /Friday through Monday/...

Wednesday through Friday Night: VFR. Breezy. 

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

Saturday Night: VFR. Breezy. 

Sunday: VFR. Breezy. Slight chance SHRA.

&&

.MARINE...
Forecaster Confidence Levels...

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

Through Thursday night: High confidence. 

Gusty southwest winds expected Thursday. Much will depend on 
how warm we can get. Have high confidence in at least Small 
Craft Advisory conditions, with moderate confidence for gale 
force gusts across some of the eastern coastal waters. Gale 
Watches expanded to interior easter MA waters where proximity to
land/better warming may help mix down marginal gale force 
winds.

Outlook /Thursday Night through Monday/...

Thursday Night: Low risk for Small Craft Advisory winds with
gusts up to 30 kt. Rough seas up to 8 ft. Slight chance of rain
showers. 

Juneteenth: Low risk for Small Craft Advisory winds with gusts
up to 25 kt. Rough seas up to 7 ft. 

Friday Night through Saturday: Low risk for Small Craft
Advisory winds with gusts up to 25 kt. Seas up to 5 ft. 

Saturday Night: Winds less than 25 kt. Seas up to 5 ft. 

Sunday: Winds less than 25 kt. Areas of seas approaching 5 ft.

&&

.BOX WATCHES/WARNINGS/ADVISORIES...
CT...None.
MA...None.
RI...None.
MARINE...Small Craft Advisory from 11 AM to 7 PM EDT Thursday for 
     ANZ230-236.
     Gale Watch from Thursday morning through Thursday evening for 
     ANZ231-234-250-251-280.
     Small Craft Advisory from 11 AM Thursday to 1 AM EDT Friday 
     for ANZ232-233.
     Small Craft Advisory from 11 AM Thursday to 8 PM EDT Friday 
     for ANZ235-237-255-256.
     Small Craft Advisory from 2 PM Thursday to 8 PM EDT Friday for 
     ANZ254.

&&

$$

DISCUSSION...BW/Frank
AVIATION...BW/Frank
MARINE...BW/Frank