Lexington Weather

Lexington, Massachusetts, USA

51°F

5/23/2025 10:44pm

Lexington Conditions: Light rain, Overcast
Temperature: 50.5°F / 10.3°C
Dew Point: 48.4°F
Relative Humidity: 92%
Wind: WSW 2 mph, 10-min avg: 2 mph, gust: 4 mph
Barometer: 29.75 in Steady
Visibility: 10 miles
Rain Today: 0.35 in

Area Forecast Discussion
for Boston / Norton, MA

        
000
FXUS61 KBOX 182318
AFDBOX

Area Forecast Discussion
National Weather Service Boston/Norton MA
718 PM EDT Sun May 18 2025

.SYNOPSIS...
Breezy and unseasonably cool temperatures are on tap tonight and 
Monday with nothing more than a few brief passing showers mainly 
north of I-90. Unseasonably cool temperatures continue for the 
remainder of the week...especially later in the week when a late 
season Nor'easter may bring a cold windswept rain late Wednesday 
into early Friday.

&&

.NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
Key Messages... 

* A few passing showers this evening...mainly north of I-90
* Breezy and cool tonight with lows in the upper 40s/lower 50s

Details...

Anomalous closed upper level low pressure system over Maine will 
slowly shift east into the Canadian Maritimes tonight. The 
associated cold pool aloft coupled with diurnal heating has allowed 
a few passing showers to develop this afternoon...mainly north of I-
90 closer to the upper level low. This activity will tend to 
dissipate later this evening with the loss of daytime heating. 

The closed upper level low shifting into the Maritimes brings cool 
advection tonight and will be accompanied by a modest NW low level 
jet. Therefore...expect W winds to shift to the NW and gust between 
20 and 30 mph tonight. The cool advection aloft will result in 
overnight lows bottoming out mainly in the upper 40s to the lower 
50s...but it will feel cooler with the northwest breeze.

&&

.SHORT TERM /6 AM MONDAY MORNING THROUGH MONDAY NIGHT/...
Key Messages...

* Breezy & unseasonably cool Mon with considerable clouds with peeks 
  of sunshine...mainly dry other than a few passing showers NE MA

* Highs Mon mainly in the 60s, but some spots in northern MA may 
  struggle to reach 60 degrees

* Breezy and unseasonably cool Mon night with lows in the 40s and 
  wind chills dropping into the 30s/lower 40s by daybreak Tue

Details...

Monday and Monday night...

The closed upper level low across the Canadian Maritimes will very 
slowly shift southeast of that region Mon into Mon night. This will 
continue to result in breezy and unseasonably cool weather across 
the region. Cyclonic flow around the upper level low will result in 
a scattered to broken deck of strato-cu clouds...despite some peeks 
of sunshine at times especially in western MA and CT. A piece of 
shortwave energy will drop south from the main upper level low and 
may bring a few brief showers to mainly northeast MA on Mon...but 
the majority of the day will feature dry weather.

High temps on Mon will be below normal for this time of year only 
reaching into the 60s. In fact...portions of northern MA especially 
the high terrain may struggle to reach 60. It will also be rather 
breezy with northwest wind gusts of 25 to 30 mph and perhaps a few 
gusts near 35 mph...so it will feel cool for this time of year. Low 
temps Mon night will bottom out in the 40s with wind chills dropping 
into the 30s/lower 40s by daybreak Tue.

&&

.LONG TERM /TUESDAY THROUGH SUNDAY/...
Key Messages:

* Cooling trend starts Tuesday and continues through the rest of the 
  week, with Wednesday and Thursday struggling to reach 60 across 
  the CWA

* Another system will likely bring rain and gusty winds to southern 
  New England in the second half of the week, though exact timing 
  and track are still uncertain

Details...

Forecast remains on track for early to mid week. Northwest flow on 
the backside of the low over the Maritimes kicks in while cooler 
temperatures aloft remain... keeping the region cooler and drier. 
Winds gradually shift to the northeast throughout Tuesday as the low 
continues to push offshore. Highs Tuesday look to hover around 60, 
while temps Wednesday and Thursday will likely struggle to reach 60 
across the CWA. Friday looks to recover a bit, with highs once again 
near 60 across the area.

A surface low is expected to move up along the east coast towards 
southern New England throughout the week. This late spring 
Nor'Easter could bring significant rainfall and gusty winds starting 
sometime in the early hours of Thursday through Friday. Timing is 
starting to get more defined, with ensembles starting to agree on 
the low passing to the southeast Thursday afternoon/evening. There 
is still significant variance in its track though. The GEM tracks 
its center right over SE MA, while the GFS and ECMWF track it to the 
southeast of Nantucket (though the GFS keeps it much further 
offshore). This uncertainty is also seen in the different ensembles' 
24 hour QPF values, where they range from around 0.45" across 
southern New England (GEFS) up to an inch in some areas (ECMWF ENS). 
If the storm remains closer to the coast, we can expect more rain 
and gustier winds. Both decrease if the low tracks further offshore. 
Regardless, wetting rains can be expected. The overall consensus is 
that the end of next week will be unsettled and cool with continued 
broad cyclonic flow and cooler temperatures aloft.

&&

.AVIATION /23Z SUNDAY THROUGH FRIDAY/...
Low - less than 30 percent.
Moderate - 30 to 60 percent.
High - greater than 60 percent.

00z TAF Update...

Tonight through Monday night...High Confidence.

A scattered to broken deck of mainly VFR clouds will continue to
impact the region through Monday night...particularly in 
northern MA. We can not rule out some brief marginal MVFR 
cigs...but overall thinking conditions will maintain VFR levels
the majority of the time. A few spot showers are possible at 
times...mainly in northern MA but even in these locations the 
vast majority of this period will feature dry weather. W winds 
shift to the NW tonight continuing from that direction Mon into 
Mon night. Gusts of 20 to 30 knots will be common right through 
Mon night. Even a few brief gusts over 30 knots will be possible
at times in the high terrain.

KBOS TAF...High Confidence in TAF.  

KBDL TAF...High Confidence in TAF.

Outlook /Tuesday through Friday/...

Tuesday: Mainly VFR, with local MVFR possible. Breezy. 

Tuesday Night: Mainly VFR, with areas MVFR possible. 

Wednesday: MVFR/IFR conditions possible. Chance SHRA.

Wednesday Night: MVFR/IFR conditions possible. Breezy. SHRA
likely.

Thursday: Mainly MVFR, with areas IFR possible. Windy with
gusts up to 35 kt. SHRA.

Thursday Night: Mainly VFR, with local IFR possible. Windy with
areas of gusts up to 35 kt. SHRA likely.

Friday: Chance SHRA.

&&

.MARINE...
Forecaster Confidence Levels:

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

Tonight through Monday night...High Confidence. 

An anomalous closed upper level low over Maine will shift into the 
Maritimes tonight and then gradually move further southeast Mon into 
Mon night. The unseasonably cool airmass will result in NW wind 
gusts of 20 to 30 knots tonight into Mon night...so small craft 
headlines are posted for all our waters.

Outlook /Tuesday through Friday/...

Tuesday through Tuesday Night: Winds less than 25 kt. Areas of
seas approaching 5 ft. 

Wednesday: Winds less than 25 kt. Areas of seas approaching
5 ft. Chance of rain showers. 

Wednesday Night: Low risk for Small Craft Advisory winds with
gusts up to 25 kt. Seas up to 5 ft. Chance of rain showers. 

Thursday: Moderate risk for gale force winds with gusts up to
35 kt. Rough seas up to 11 ft. Rain showers likely. 

Thursday Night: Low risk for gale force winds with gusts up to
35 kt. Rough seas up to 11 ft. Chance of rain showers. 

Friday: Winds less than 25 kt. Rough seas up to 10 ft. Chance
of rain showers.

&&

.BOX WATCHES/WARNINGS/ADVISORIES...
CT...None.
MA...None.
RI...None.
MARINE...Small Craft Advisory until 11 PM EDT Monday for ANZ230-236.
     Small Craft Advisory until 5 AM EDT Tuesday for ANZ231>235-237-
     250-251-254>256.

&&

$$

SYNOPSIS...Frank/McMinn
NEAR TERM...Frank
SHORT TERM...Frank
LONG TERM...McMinn
AVIATION...Frank/Dooley/McMinn
MARINE...Frank/McMinn