Lexington Weather

Area Forecast Discussion
for Boston / Norton, MA

        
000
FXUS61 KBOX 141721
AFDBOX

Area Forecast Discussion
National Weather Service Boston/Norton MA
121 PM EDT Sat Mar 14 2026

.WHAT HAS CHANGED...
Expanded the Wind Advisory into Cape Cod, Martha's Vineyard and
Nantucket for today, while also upgrading marine headlines to
Gale Warnings for all waters.

&&

.KEY MESSAGES...

- Variable amounts of cloud cover, cooler than normal with
  strong west wind gusts 35-50 mph today. 

- A period of heavy rainfall Mon into Mon night may lead to some
  river and small stream flooding. A period of strong to
  damaging wind gusts possible Mon night.

- Mainly dry weather and trending colder through midweek then 
  moderating toward the end of next week.

&&

.DISCUSSION...
KEY MESSAGE 1...Variable amounts of cloud cover, cooler than normal 
with strong west wind gusts 35-50 mph today. 

Strong Clipper low pressure system is expected to pass to our 
north and into the Canadian Maritimes by tonight. Pretty tight 
pressure gradient combined with efficient if still shallow 
mixing from a strong cold advection pattern should help to 
promote gusty to strong westerly wind gusts today. This system 
has had a history of strong westerly winds yesterday (e.g. 
several instances of 50 to 60 mph gusts) in the eastern Gt Lakes
region, but the westerly lower-level jet doesn't look nearly as
robust as it did yesterday, although is still considerable at 
around 45-50 kt at 850 mb. 

Boosted wind gusts upward some for today, and most areas should
end up gusting in the 35-45 mph range; however gusts could 
punch as high as 50 mph across the Berkshires, northern hills of
Worcester County and down across the Cape and Islands where the
existing Wind Advisory has now been expanded further into. This
is supported by BUFKIT momemtum transfer progs as well as the 
00z HRRR 10-m wind gust speeds, and the HREF ensemble minimum 
10-m gust is also around 40-45 kt in the Advisory areas. 
Westerly gusts should really pick up once the sun comes out this
morning but should peak into the afternoon as the core of the 
low-level jet crosses Southern New England. Gusts should drop 
below 40 mph by late afternoon, with a steadier decrease into 
the night as winds turn more northwesterly and lighter. 

It wouldn't take much more of an increase in gusts to warrant 
expanding the Wind Advisory further into Southern New England, 
especially given continued early-morning observations of 35-45 
kt gusts across western NY and the Gt Lakes. It does look to be 
at least a variably-cloudy day (more clouds north and fewer 
south) as moisture continues to wrap-around from the Clipper 
system, which casts some uncertainty in the mixing depth and 
that was a factor in deciding not to expand the Advisory into 
remainder of Southern New England. Other than the cloud cover, 
there may also be some scattered flurries or sprinkles dotting 
the area as this is a favorable setup for Gt Lakes moisture to 
be advected quite a distance downwind given the enhanced 
westerly jet, but this should be fewer and far betweeen and not 
impactful. Besides the windy conditions and the variable amts of
cloud cover, today is otherwise a cooler day with highs in the 
upper 30s to low 40s, a couple degrees cooler than normal but 
the wind will add a bit of chill.

KEY MESSAGE 2...A period of heavy rainfall Mon into Mon night may 
lead to some river and small stream flooding. A period of strong to 
damaging wind gusts possible Mon night.

Ensemble guidance showing a strong signal for a heavy rainfall and 
strong wind event Mon into Mon night. PWAT and low level wind 
anomalies 3-4 SD above normal which is near the maximum of the CFSR 
climatology. This occurs ahead of a deep and amplified upper trough 
over the Gt Lakes which sends anomalous moisture northward into New 
Eng. Expect numerous showers Mon as anomalous PWAT plume overspreads 
the region within the low level jet axis. There is also some 
elevated instability so potential exists for heavy convective 
showers and a few t-storms as well. These locally heavy showers and 
isolated thunder will continue into Mon night. Given the strong 
forcing along the boundary along with some elevated instability a 
fine line of convection may develop along the front as it moves 
through during Mon night. The front should be moving off the coast 
by Tue morning with rapid drying moving from west to east. We are 
still expecting average rainfall of 1-2 inches with localized 
amounts up to 3 inches. 90th percentile of the ensemble QPF 
distribution continues to show rainfall amounts up to 3 inches which 
likely represents a high end potential from convection. MMEFS 
ensemble guidance continues to target RI rivers (Pawcatuck, Wood and 
Pawtuxet) and the lower reaches of the CT River from Hartford to 
Middle Haddam with the highest probabilities for (50-80%) for minor 
flooding during Tue-Wed timeframe. 

While winds will be ramping up during Mon, the worst of the wind 
will likely be focused during the Mon night period just ahead of the 
cold front. This is when the maximum of the low level jet lifts 
across the region. NAM is indicating 85-90 kt LLJ at 925 mb moving 
across SE New Eng. Even the global guidance is showing 75-80 kt. 
Soundings do show a low level inversion which is normal with these 
southerly LLJ events so the challenge is determining how much wind 
can mix down. The key will be how mild it gets Mon evening ahead of 
the cold front and whether a fine line of convection can develop 
along the front which would increase potential for mixing strong 
winds to the surface. These are factors that should become more 
clear as we get within the hi-res window later this weekend. A quick 
look at the soundings suggest temps near 60 would increase damaging 
wind potential and there is certainly a chance we see temps get to 
60 in some locations. But just taking 50 percent of the LLJ as an 
initial estimate with a strong inversion in place would support 45-
55 mph gusts, while a weakened inversion with milder temps would 
increase potential for 55-65 mph gusts. 

KEY MESSAGE 3...Mainly dry weather and trending colder through 
midweek then moderating toward the end of next week. 

It appears the front will have moved east of New Eng before 12z Tue 
with much drier air moving in from the west so expecting mainly dry 
weather Tue. The dry weather will continue Wed & Thu and possibly 
into Fri as well but we may have to contend with a shortwave and 
cold front which could bring a low risk for showers on Fri. It will 
be trending colder with the coldest day on Wed as 850 mb temps 
bottom out around -15 to -18C at 12z Wed. Highs Wed expected to be 
mostly in the 30s to near 40. Then temps gradually moderate Thu into 
Fri getting back to seasonable normals by Fri.

&&

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

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

Rest of Today and Tonight... High Confidence

VFR. 30+ knot westerly winds remain possible through about 00Z. 
Thereafter expect winds to gradually weaken with gusts below 20 
knots by 06Z. Winds become northwest around 5 knots after 06Z.

Sunday... High Confidence

VFR. Winds becoming east/southeast between 5 and 10 knots after 15Z.

Sunday Night...High Confidence

Deteriorating conditions Sunday night into Monday as a warm front 
lifts north over the region. MVFR/IFR ceilings and visibility 
developing after 06Z as light to moderate rain overspreads southern 
New England.

KBOS Terminal...High confidence.

KBDL Terminal...High confidence

Outlook /Monday through Thursday/...

Sunday: VFR. Breezy. 

Sunday Night: Mainly VFR, with local IFR possible. Windy with
local gusts up to 30 kt. Chance RA, chance FZRA.

Monday: Mainly MVFR, with areas IFR possible. Strong winds with
areas of gusts up to 40 kt. RA, slight chance TSRA.

Monday Night: Mainly MVFR, with local IFR possible. Strong
winds with gusts up to 50 kt. RA, isolated TSRA.

Tuesday: VFR. Windy with gusts up to 35 kt. 

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

Wednesday: VFR. Breezy.

&&

.MARINE...
Forecaster Confidence Levels...

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

High confidence. 

Have upgraded SCAs/Gale Watch to Gale Warnings, which now cover
all waters for today into early tonight. Gusts look to punch a
little higher than prior expectations, with westerly gusts in 
the 35-45 kt range, but on the higher end of that range over the
southern/southeast waters. Expect rough seas especially
eastern/southern outer waters. Gradual decrease in winds and
seas through SCA range into tonight and early Sunday AM. 

Winds and seas then decrease below SCA criterion for Sunday. 

However increasing southerly winds ahead of a strong low 
pressure should take place starting Sunday night. Gale/Storm 
Watches could become necessary very late Sunday night/early 
Monday.

Outlook /Monday through Thursday/...

Sunday: Winds less than 25 kt. 

Sunday Night: Moderate risk for Small Craft Advisory winds with
gusts up to 30 kt. Local rough seas. Chance of rain. 

Monday: Moderate risk for gale force winds with gusts up to
45 kt. Rough seas up to 15 ft. Rain, slight chance of
thunderstorms. 

Monday Night: gale force winds with gusts up to 45 kt. Rough
seas up to 19 ft. Rain, isolated thunderstorms. 

Tuesday: Strong winds with gusts up to 35 kt. Rough seas up to
15 ft. Slight chance of rain. 

Tuesday Night: Moderate risk for Small Craft Advisory winds
with gusts up to 30 kt. Rough seas up to 14 ft. 

Wednesday: Winds less than 25 kt. Areas of rough seas.

&&

.BOX WATCHES/WARNINGS/ADVISORIES...
CT...None.
MA...Wind Advisory until 7 PM EDT this evening for MAZ002-004-008-
     009-022>024.
     High Wind Watch from Monday afternoon through late Monday 
     night for MAZ005>007-013>024.
RI...High Wind Watch from Monday afternoon through late Monday 
     night for RIZ001>008.
MARINE...Gale Warning until 11 PM EDT this evening for ANZ230>237-250-
     251-254>256.
     Storm Watch from Monday afternoon through Tuesday morning for 
     ANZ230>237-250-251-254>256.

&&

$$

DISCUSSION...Frank/RM
AVIATION...RM
MARINE...KJC/Loconto/RM