Lexington Weather

Lexington, Massachusetts, USA

63°F

4/26/2025 8:21pm

Lexington Conditions: Overcast
Temperature: 63.0°F / 17.2°C
Dew Point: 61.5°F
Relative Humidity: 95%
Wind: Calm, 10-min avg: Calm, gust: None
Barometer: 29.62 in Steady
Visibility: 10 miles
Rain Today: 0.64 in

Area Forecast Discussion
for Boston / Norton, MA

        
000
FXUS61 KBOX 231953
AFDBOX

Area Forecast Discussion
National Weather Service Boston/Norton MA
353 PM EDT Wed Apr 23 2025

.SYNOPSIS... 

Chilly tonight as a result of radiational cooling. Pleasant and dry 
under high pressure continuing through Thursday, with the exception 
of a slight chance of showers Thursday evening/night across northern 
Massachusetts. Unseasonably warm on Friday before A system on
Saturday brings the next chance for widespread rainfall, though
exact details remain uncertainty. Drier conditions return late 
this weekend into early next week.

&&

.NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...

Key Messages...

* Clear skies, light winds, and cooler temps tonight. 

Zonal flow in the mid- and upper- levels continues tonight as a 
surface high builds to the south. Decreasing winds and clear skies 
will allow for a good amount of radiational cooling and decoupling 
of the boundary layer, leading to  overnight lows in the high 30s to 
low 40s outside of the typical urban corridors to cool into the 
upper 30s and low 40s.

&&

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

Short Term

Key Messages...

* Warmer, clear skies, and light winds for a pleasant Thursday.

* Chance of showers Thursday evening north of the Mass Pike.

A mid-level ridge stretching into southern Quebec together with 
surface high pressure just offshore will prolong the quiet and dry 
weather through Thursday. The only exception is for western and 
central MA which may be in close enough proximity to a weak 
shortwave and moisture plume to our north to support widely 
scattered showers Thursday evening north of the Mass Pike. 
Temperature-wise, we will warm a few degrees on Thursday afternoon 
as warm advection in the low levels pushes 925 mb temps to 12-15C 
which would result in highs in the upper 60s and mid 70s across the 
interior and high 50s to mid 60s along the immediate coasts, Cape, 
and Islands. Wind gusts pick up a little for Thursday night along 
the south coast, Cape, and Islands as a warm front approaches 
southern New England.

&&

.LONG TERM /FRIDAY THROUGH WEDNESDAY/...

Key Messages:

* Unseasonably warm Friday    

* Soaking rain Saturday, but timing remains uncertain 

* Drying out Sunday with cool and blustery conditions
 
* Mainly dry with warming temperatures Monday through Wednesday


Unseasonably warm on Friday as flow turns SW and 850mb temps warm to 
+10C. Even with partly to mostly cloudy skies due to weak WAA, high 
temps will reach the mid to upper 70s to even low 80s near the CT 
river valley. Closer to the coasts, highs will struggle to jump out 
of the low to mid-60s with a modest southerly breeze.  

A short wave trough exits the Great Lakes Saturday as a surface low 
out ahead of it passes over northern New England. This system will 
bring our next round of precipitation to the region as PWATs 
increase to 1.3 to 1.5 inches. The timing of the rain remains 
uncertain as the GFS remains faster than the Euro and Canadian. 
However, the 12z run has started to trend slower, with the bulk of 
the precipitation falling during the daylight hours on Saturday. 
There could be a rumble or two of thunder, as steep mid-level lapse 
rates allow for elevated instability to build to 100-300J/kg. As of 
now, still expecting a modest rainfall as ensemble probs from the 
12z GEFS and ECWMF show moderate to high probs of 40-70% for a half 
inch of rain. Ensemble probs drop off significantly for greater than 
1 inch, ranging between 0-10%. Thinking there will be pockets of 
greater than 1 inch, but they will be more localized to pockets 
where convection can help increase rain rates. It will be quite 
windy on Saturday as a southerly LLJ of 45-55 knots develops over 
eastern MA and RI. With cold ocean waters still in the 40s, it will 
be tough to mix down much of that wind. Hence, gusts should stay in 
the 25-35mph range. High temps range from the low to upper 60s. 

Drying out Sunday as cool and dry air advects in from the north. 
Winds turn gusty again around 30-40mph as the pressure gradient 
remains tight, and northerly winds promote good mixing.  High temps 
will struggle to top the low 60s even with mostly sunny skies.

Upper-level ridge builds back in to start the week with mainly dry 
conditions through Wednesday.  High temperatures quickly moderate 
back into the low 70s on Monday, with mid to upper 70s on Tuesday 
and Wednesday.

&&

.AVIATION /20Z WEDNESDAY THROUGH MONDAY/...
Low - less than 30 percent.
Moderate - 30 to 60 percent.
High - greater than 60 percent.

18Z TAF Update:

Today through 00Z: High Confidence

VFR. W-NW winds 5-10kts with some sea breezes near the south
coast and Cape.

Tonight: High Confidence

VFR. Northerly winds 5-10kts becoming light and variable in the
early morning hours.

Thursday: High Confidence. 

VFR. Winds light and variable, becoming southerly 5-10 kts in
the afternoon.

Thursday Night: High Confidence.

VFR. Primarily SSWly winds 5-10kts with a few sporadic gusts up
to 15kts.
 
KBOS TAF...High confidence in flight categories. Low confidence
in sea breeze... chance it could come in later around 21-22Z.
Onshore flow/sea breezes likely Thursday.

KBDL TAF...High confidence in TAF. 

Outlook /Friday through Monday/...

Friday: VFR. Breezy. 

Friday Night: Mainly VFR, with local IFR possible. Breezy.
Chance RA.

Saturday: Mainly MVFR, with local IFR possible. Windy with
gusts up to 30 kt. RA likely, slight chance TSRA.

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

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

Sunday Night through Monday: VFR. 

&&

.MARINE...
Forecaster Confidence Levels:

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

Key Messages

* Generally quiet conditions over the coastal marine zones through 
  Thursday night.

Tonight

Quiet and calm across the coastal waters tonight with winds becoming 
light south/southwest winds becoming northeast by tomorrow morning. 
Seas generally 2 feet or less.

Tomorrow

High pressure to the south of the coastal waters will support 
another calm day with light northeast winds in the morning becoming 
steady out o of the south during the afternoon from 10 to 15 knots. 
Seas remain 2 feet or less.

Tomorrow Night

South/southwest winds up to 10 knots with seas building to 2-3 feet.

Outlook /Friday through Monday/...

Friday: Winds less than 25 kt. 

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

Saturday: Moderate risk for Small Craft Advisory winds with
local gusts up to 30 kt. Areas of rough seas. Rain, slight
chance of thunderstorms. 

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

Sunday: Moderate risk for Small Craft Advisory winds with gusts
up to 30 kt. Areas of seas approaching 5 ft. 

Sunday Night: Winds less than 25 kt. Seas locally approaching
5 ft. 

Monday: Winds less than 25 kt. 

&&

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

&&

$$

SYNOPSIS...McMinn/KP
NEAR TERM...McMinn/RM
SHORT TERM...McMinn/RM
LONG TERM...KP
AVIATION...McMinn/KP
MARINE...McMinn/KP/RM