Lexington Weather

Lexington, Massachusetts, USA

27°F

12/3/2024 1:10am

Lexington Conditions: Partly cloudy
Temperature: 26.8°F / -2.9°C
Dew Point: 19.2°F
Relative Humidity: 73%
Wind: Calm, 10-min avg: Calm, gust: None
Barometer: 30.08 in Steady
Rain Today: 0.00 in

Area Forecast Discussion
for Boston / Norton, MA

        
000
FXUS61 KBOX 291134
AFDBOX

Area Forecast Discussion
National Weather Service Boston/Norton MA
634 AM EST Fri Nov 29 2024

.SYNOPSIS...
Drying out today with seasonable temperatures, then colder but 
mainly dry weather follows this weekend and into much of next 
week.

&&

.NEAR TERM /THROUGH TONIGHT/...
Main tweaks this morning were to sky cover and temperatures to
reflect observed trends. Some lake effect clouds had made it 
over the Berkshires into the CT RIver Valley. Already seeing 
signs of these clouds dissipating from the south, and 
expecting this trend will continue once more boundary layer 
mixing commences. More clouds still expected to arrive later
this afternoon.

Previous Discussion...

Southern New England should be between most major weather
features today. Yesterday's low pressure is now over the
Maritimes. Another low pressure will be near James Bay. This
will maintain a general cyclonic flow across our region, but
provide no real focus to trigger showers. A lack of moisture for
most of the daylight hours will not help to generate showers
either. A sheared mid level shortwave and increased humidity may
reach western MA late today, which is when showers would be 
more of a possibility.

The other aspect we will need to monitor today is the 
possibility for ocean-effect showers. With a general west wind
today, the majority of these showers would be either well
offshore or south of New England, where the fetch will be
better.

Near normal high temperatures for late November.

&&

.SHORT TERM /SATURDAY/...
Not much change to the overall pattern tonight into Saturday, so
not much change to the overall forecast. Showers towards western
MA should diminish this evening as the mid level shortwave moves
on. Ocean-effect showers should still come and go south of New
England, and perhaps may extend far enough north to reach the
Vineyard and Nantucket at times. This is just a low chance for
showers, and weather should be dry most of this time. Turning
colder tonight into Saturday, but just slightly below normal
temperatures expected.

&&

.LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/...
Key Points

 -Mainly dry and cold for the weekend and into the middle of
  next week.

 -Next chance for precip could be sometime late next week.

The upper air pattern remains stalled out through the end of the 
weekend and into next week, with a blocking ridge over the
western CONUS keeping us in the east under a troughing pattern. 
This will result in several days of dry, cold, and at times
blustery weather. High temperatures will struggle to reach 40F, 
with below-freezing temps in the high terrain of NW
Massachusetts. Low temperatures will drop into the high teens to 
low 20s across the region. There could be some ocean effect
rain/snow showers, but most should end up well offshore of the
coastal waters.

The next chance for measurable precipitation comes sometime in
the middle to end of next week as the upper level blocking
pattern begins to break down. The deterministic GFS consistently 
brings a low-pressure system through Thursday. However, this
appears to be an outlier compared to the GEFS system, with very 
few members showing a low-pressure system near SNE. Temperatures
remain uncertain at this time range, but there are some early 
indications for an arctic airmass moving in late next week into 
the following weekend. Both the GEFS and Euro ensembles
currently show a 10 to 30% chance for a - 20 degree temperature
anomaly.

&&

.AVIATION /12Z FRIDAY THROUGH TUESDAY/...
Forecast Confidence Levels:

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

Through Saturday: High Confidence

VFR for most of this time. Local MVFR in spotty showers towards
western MA late this afternoon into this evening. Areas MVFR
possible south of New England, which could impact ACK at times,
late tonight into Saturday. 

Gusty west winds through this portion of the forecast, but not
quite as gusty at night.

KBOS Terminal...High confidence in TAF.

KBDL Terminal...High confidence in TAF.

Outlook /Saturday Night through Tuesday/...

Saturday Night: VFR. Breezy. Slight chance FZRA.

Sunday: VFR. Breezy. 

Sunday Night through Tuesday: VFR.

&&

.MARINE...
Forecaster Confidence Levels:

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

Through Saturday...

Low pressure over the Maritimes, and another low pressure over
James Bay, will maintain a general gusty west wind across the 
waters, but not quite as strong as yesterday. Seas will take
longer to subside, especially across the outer coastal waters.
Adjusted the timing of Small Craft Advisories based on recent
observations. This included extending the advisory for Rhode
Island Sound a little longer. Further extensions to the timing
for the outer coastal waters are likely.

Outlook /Saturday Night through Tuesday/...

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

Sunday: Winds less than 25 kt. Local rough seas. Slight chance
of rain showers. 

Sunday Night: Winds less than 25 kt. Areas of seas approaching
5 ft. Slight chance of rain showers. 

Monday: Winds less than 25 kt. Seas locally approaching 5 ft.
Slight chance of rain showers. 

Monday Night through Tuesday: Winds less than 25 kt. Slight
chance of rain.

&&

.BOX WATCHES/WARNINGS/ADVISORIES...
CT...None.
MA...None.
RI...None.
MARINE...Small Craft Advisory until 7 AM EST this morning for ANZ232-
     233-237-251.
     Small Craft Advisory until 10 AM EST this morning for ANZ235.
     Small Craft Advisory until 4 PM EST this afternoon for ANZ250.
     Small Craft Advisory until 7 PM EST Saturday for ANZ254>256.

&&

$$

SYNOPSIS...Belk/KP
NEAR TERM...Belk
SHORT TERM...Belk
LONG TERM...KP
AVIATION...Belk/KP
MARINE...Belk/KP