Lexington Weather

Lexington, Massachusetts, USA

66°F

5/20/2024 3:06pm

Lexington Conditions: Clear
Temperature: 65.8°F / 18.8°C
Dew Point: 56.5°F
Relative Humidity: 72%
Wind: Calm, 10-min avg: Calm, gust: 3 mph
Barometer: 29.99 in Steady
Visibility: 10 miles
Rain Today: 0.00 in

Area Forecast Discussion
for Boston / Norton, MA

        
000
FXUS61 KBOX 132311
AFDBOX

Area Forecast Discussion
National Weather Service Boston/Norton MA
711 PM EDT Mon May 13 2024

.SYNOPSIS...
A warm front brings widely scattered showers tonight followed 
by much warm weather tomorrow, a couple of showers and/or an
isolated thundershower are possible in the interior Tuesday 
afternoon. Unsettled weather Wednesday through the weekend with
more clouds than sun and periods of rain. Seasonable 
temperatures through the upcoming weekend.

&&

.NEAR TERM /THROUGH TUESDAY/...
Update: 3PM

Overall a stunner of an afternoon with many enjoying a sun-filled
afternoon while others are stuck beneath diurnal cumulus which 
developed along the sea-breeze boundary. As these diurnal clouds
wane this afternoon, mid and high clouds increase from the west
ahead of a warm front. Stepping outside this evening should 
enjoy temperatures in the low 60s and falling into the upper 50s
shortly after sunset. 850mb jet advects higher PWATs between 
1.0 and 1.3 inch tonight and with the warm front passing through
a few showers possible, though the best forcing looks to be 
limited to northern Massachusetts and points north into Vermont 
& New Hampshire. No washouts are expected, QPF is in the 
neighborhood of a few hundredths of an inch. South to southwest 
winds overnight are less than 10 mph. Nighttime lows are on 
either side of 50 degrees.

&&

.SHORT TERM /TUESDAY NIGHT THROUGH 6 PM TUESDAY/...
Update: 3PM

A warm and summer-like head is on tap! With the passage of the warm 
front Monday night, we are placed in the warm sector. Clouds from 
overnight do linger across northern Massachusetts, but will give way 
to partly sunny skies and fairly mild temperatures. Deep southwest 
flow usher in warmer and a more humid air mass. 925mb temperatures 
climb to +14C to +18C and BUFKIT shows a well mixed boundary layer 
tomorrow, highs will easily climb into the middle 70s away from the 
coast. It's not out of the question a few spots like the Merrimack 
and Connecticut River Valley top out around 80 degrees. Back to the 
coast, the southwest flow is an onshore wind for coastal Rhode 
Island and southeast Massachusetts, here the temperature Tuesday 
afternoon only reaches the upper 60s and low 70s. Southwest winds 
become gusty as well, 15 to 25 mph. Shower are limited to northwest 
Massachusetts during the late afternoon where the best moisture and 
instability are located. HREF ensembles have roughly 500-1000 units 
of MUCAPE along and west of the Berkshires, so it's possible there 
may be an iso. non severe thunderstorm. Rain chances expand 
throughout the overnight hours with a mid-level trough and frontal 
boundary approaching from the west. Winds ease overnight becoming 
more south less than 10 mph. Night lows fall into the middle and 
upper 50s.

&&

.LONG TERM /TUESDAY NIGHT THROUGH MONDAY/...
Update: 3PM

Highlights

* Unsettled weather Wednesday through the weekend with more clouds 
  than sun and periods of rain

* Seasonable temperatures through the weekend

Wednesday and Thursday

A coastal low pressure system will pass well south of southern New 
England during the day Wednesday. Nonetheless, modest synoptic 
forcing and PWATs greater than 1 inch should support periods of rain 
during the day Wednesday. Accumulations will be modest with the 
strongest forcing to our south, but somewhere between 0.1 and 0.25 
inches between Wednesday and Thursday morning should be in the cards 
for portions of southern New England. Downstream blocking has 
resulted in model guidance trending toward a slower departure of 
this system with cloud cover and showers lingering into the first 
half of Thursday for much of the forecast area. A mid-level ridge 
building in from the west may salvage a partly sunny day for the 
western areas on Thursday afternoon. Expect somewhat gusty southwest 
winds on Wednesday with northeast gusts along the east coast on 
Thursday. 

Friday through the weekend

The forecast remains unsettled late week through the weekend. As the 
mid-week coastal low departs over the Atlantic Friday afternoon, a 
short-wave dropping down from The Great Lakes will support the 
development of another surface low-pressure system that is likely to 
bring cloudiness and periods of rain to southern New England this 
weekend. Confidence in timing, duration, and intensity of potential 
rainfall is low at this time so we have leaned on the NBM for 
guidance at this time range. Temperatures look to be seasonably 
persistent through the weekend with daily lows in the low to mid 50s 
and daily highs ranging from the low 60s to low 70s. Coastal 
locations continue to run cooler  with highs in the upper 50s/low 
60s more common on days with onshore flow.

&&

.AVIATION /23Z MONDAY THROUGH SATURDAY/...
Forecast Confidence Levels:

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

00Z TAF Update

Tonight...High confidence.

VFR. Scattered showers are possible across northern MA, with at
times briefly lower VFR CIGs 3-5k ft. Winds are south to
southwest 5 to 10 knots.

Tuesday...High confidence.

VFR. A few convective showers possible across interior MA and
northern CT during the afternoon. Steady southwest winds with
gusts developing in the afternoon 20 to 25 knots. 

Tuesday Night...Moderate confidence. 

VFR to start, becoming MVFR/IFR heading later into the night
with increasing rain chances from west to east. Southwest winds
8 to 12 knots early, becoming south 5 to 10 knots. 

KBOS TAF...High confidence in TAF. 

VFR. Breezy southwest winds with gusts 20 to 25 knots fend off
any sea-breeze potential on Tuesday. Rain chances increase 
Tuesday night.


KBDL TAF...High confidence in TAF. 

Increasing wind speeds Tuesday with gusts 20 to 25 knots 
possible. Dry for most of Tuesday as well, rain arrives after 
00z. 

Outlook /Tuesday Night through Saturday/... 

Tuesday Night: Mainly VFR, with local IFR possible. Breezy.
Chance SHRA.

Wednesday: Mainly MVFR, with local IFR possible. Chance SHRA.

Wednesday Night: Mainly VFR, with local IFR possible. Breezy.
Chance SHRA.

Thursday: Mainly VFR, with local MVFR possible. Windy with
local gusts up to 30 kt. Chance SHRA.

Thursday Night: VFR. Breezy. Chance SHRA.

Friday: VFR. Breezy. Slight chance SHRA.

Friday Night: VFR. Chance SHRA.

Saturday: Mainly VFR, with local IFR possible. Chance SHRA.

&&

.MARINE...
Forecaster Confidence Levels:

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

Update: 3PM

Tonight through Tuesday night....

Southwest to south winds this evening with winds speeds between 10 
and 15 knots, seas area generally less than 3 feet, near 4 feet on 
the outermost waters. A robust southwest jet brings period of more 
gusty winds Tuesday afternoon between 20 and 35 knots and seas 
building to 4 feet, it is possible later crew could issue a Small 
Craft Advisory, especially for the northeast waters where there is a 
greater likelihood. Winds diminish Tuesday night with rain chances 
during the second-half of the night. 

Outlook /Tuesday Night through Saturday/... 

Tuesday Night: Winds less than 25 kt. Seas locally approaching
5 ft. Slight chance of rain showers. Local visibility 1 to
3 nm.

Wednesday: Winds less than 25 kt. Chance of rain showers. 

Wednesday Night: Winds less than 25 kt. Local rough seas.
Chance of rain showers. 

Thursday: Moderate risk for Small Craft Advisory winds with
gusts up to 30 kt. Areas of rough seas. Chance of rain showers.

Thursday Night: Low risk for Small Craft Advisory winds with
gusts up to 30 kt. Areas of rough seas. Chance of rain showers.

Friday: Low risk for Small Craft Advisory winds with gusts up
to 25 kt. Seas up to 5 ft. Slight chance of rain showers. 

Friday Night: Winds less than 25 kt. Seas up to 5 ft. Slight
chance of rain showers. 

Saturday: Winds less than 25 kt. Seas up to 5 ft. Chance of
rain showers.

&&

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

&&

$$

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