Lexington Weather

Lexington, Massachusetts, USA

63°F

4/26/2025 8:11pm

Lexington Conditions: Overcast
Temperature: 63.0°F / 17.2°C
Dew Point: 61.5°F
Relative Humidity: 95%
Wind: SW Calm, 10-min avg: 2 mph, gust: 8 mph
Barometer: 29.62 in Steady
Visibility: 10 miles
Rain Today: 0.64 in

Area Forecast Discussion
for Boston / Norton, MA

        
000
FXUS61 KBOX 221904
AFDBOX

Area Forecast Discussion
National Weather Service Boston/Norton MA
304 PM EDT Tue Apr 22 2025

.SYNOPSIS...
Warm and dry on Wednesday followed by a chilly Wednesday night
driven by radiational cooling. Thereafter, mainly dry and warm 
conditions to round out the work week, then a frontal system 
will bring widespread rainfall around Saturday although exact 
details remain uncertain. Drying out and cooler Sunday behind 
the system, then milder early next week.

&&

.NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/...
Near Term

Key Messages

* Dry cold frontal passages supports clearing overnight

Tonight

A cold front pushes through the region overnight and removes the 
remaining fog/low stratus over The Cape/Islands region. Winds will 
shift to the northwest around 10 knots. 925 hPa temps drop to around 
5 Celsius. Although skies will be clear, steady northwest flow 
should limit maximum radiational cooling. Thus, expect low temps in 
the upper 40s to low 50s which is slightly above normal for mid-late 
April.

&&

.SHORT TERM /6 AM WEDNESDAY MORNING THROUGH WEDNESDAY NIGHT/...

Short Term

Key Messages

* Warm/dry weather on Thursday with steady northwest winds

* Below normal low temperatures Wednesday night into Thursday with
  lows in the upper 30s to low 40s


Tomorrow

Seasonable day tomorrow across southern New England. Quiet weather 
with high pressure building in from the west. Gradient wind 
continues to support steady northwest winds across the region from 5 
to 10 mph. Expect efficient mixing in the afternoon that could 
support a few 20 mph gusts, but nothing impactful. With 925 hPa 
temps around 10C we can expect high temps in the upper 60s to low 
70s. The coastal locations and especially The Cape/Islands will be 
substantially cooler in the upper 50s to low 60s. There is a chance 
for a sea-breeze tomorrow afternoon, mainly on the south shore. Model 
guidance is less aggressive for a circulation developing from Boston 
to Gloucester.

Tomorrow Night

Clear skies and light winds under high pressure should support a 
strong radiational cooling night. Expect well below normal 
temperatures on Thursday morning in the upper 30s to low 40s. The 
urban heat islands may be more mid to upper 40s after a warm day 
Wednesday.


&&

.LONG TERM /THURSDAY THROUGH TUESDAY/...

Key Messages:

* Warm and mostly dry Thursday and Friday, outside of a stray shower 
  in northern Massachusetts Thursday evening 

* Potential for widespread rainfall around Saturday, but there is 
  uncertainty with the exact timing. 

* Drier and cooler conditions Sunday 

* Mainly dry and milder early next week

Details...

Broad ridging aloft Thu into Fri will bring mainly dry and warm 
conditions for late April. A northern stream shortwave passage well 
to the north with a plume of moisture north of a weak warm front 
will impact mainly northern New Eng with some showers late Thu into 
Thu night. A few of these showers could spill into northern MA Thu 
evening, otherwise looking at dry conditions. Temps will average 
well above normal with 70s away from the south coast. Warmest day 
will be Friday where some CT valley locations could approach 80. 

The next chance for appreciable rainfall will be sometime around 
Saturday as amplifying northern stream trough moves through with a 
cold front interacting with anomalous PWAT plume approaching 1.5 
inches. There are timing differences among the global guidance with 
GFS the most progressive with bulk of rainfall Fri night. Given the 
progressive bias of the GFS, we leaned toward a slower solution 
which is consistent with deterministic ECMWF as well as EPS 
ensembles which have most of the rainfall on Saturday. The 25th to 
75th percentile of the ensemble distribution from GEFS, EPS and CMC 
is about 0.25 to 0.75" which is a reasonable first guess forecast of 
expected rainfall. There is some elevated instability which could 
lead to convective elements and locally heavier rainfall if 
convection occurs. 

Even the slower ECMWF has the cold front offshore by 12z Sun with 
mainly dry and cooler conditions Sun which is supported by large 
majority of EPS ensembles. Temps may be cooler than forecast, 
especially eastern New Eng where cooler low level temps linger. Then 
upper level ridging gradually builds eastward from the Gt Lakes Mon 
and Tue with rising heights and milder temps returning as high pres 
gradually shifts east of New Eng with SW flow developing. 


&&

.AVIATION /19Z TUESDAY THROUGH SUNDAY/...
Low - less than 30 percent.
Moderate - 30 to 60 percent.
High - greater than 60 percent.

18Z TAF Update:

Through 00Z: High Confidence

VFR across the interior with steady west winds around 10 knots
with some gusts to 20 knots. IFR/LIFR over The Cape Islands with
fog and low stratus. Sea-breeze at BOS may persist through
20-22Z. Confidence in sea-breeze activity is moderate at best.

Tonight: High Confidence

VFR. West/northwest winds 5-10 knots. IFR/MVFR cigs and vsbys
persist over The Cape/Islands through about 06Z before clearing
to VFR.

Tomorrow: High Confidence

VFR. West/northwest winds around 10 knots. About a 50/50 chance
for a sea-breeze at BOS, but likely would be after 18Z if it
develops.

Tomorrow Night: High Confidence

VFR. Light and variable winds.
 
KBOS TAF...High confidence in VFR. Lower confidence in sea-
breeze activity. Current onshore flow may persist through as
late as 22Z, but thinking closer to 20-21Z at this time.

KBDL TAF...High confidence in TAF. 

Outlook /Thursday through Sunday/...

Thursday through Friday: VFR. 

Friday Night: Mainly VFR, with local MVFR possible. Breezy.
SHRA likely.

Saturday: Mainly MVFR, with local IFR possible. Breezy. SHRA,
isolated TSRA.

Saturday Night: VFR. Breezy. Chance SHRA.

Sunday: VFR. Breezy. 

&&

.MARINE...
Forecaster Confidence Levels:

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

Tonight through Tomorrow Night

A cold front crosses the waters tonight resulting in a wind shift to 
the northwest. This will also  help usher out any remaining fog/low 
stratus over the south coastal waters. High pressure builds in from 
the west tomorrow and will support calm conditions over the coastal 
waters through Thursday.

Outlook /Thursday through Sunday/...

Thursday through Friday: Winds less than 25 kt. 

Friday Night: Winds less than 25 kt. Seas locally approaching
5 ft. Chance of rain showers. 

Saturday: Low risk for Small Craft Advisory winds with gusts up
to 20 kt. Seas up to 5 ft. Rain showers likely. 

Saturday Night: Low risk for Small Craft Advisory winds with
gusts up to 20 kt. Seas up to 5 ft. Chance of rain showers. 

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

&&

.BOX WATCHES/WARNINGS/ADVISORIES...
CT...None.
MA...None.
RI...None.
MARINE...None.

&&

$$

SYNOPSIS...KJC/RM
NEAR TERM...RM
SHORT TERM...RM
LONG TERM...KJC
AVIATION...KJC/RM
MARINE...KJC/RM