Lexington Weather

Lexington, Massachusetts, USA

32°F
2/14/2025 12:35am 
  • Lexington Conditions: Clear
  • Temperature: 31.5°F / -0.3°CColder 0.7°F than last hour.
  • Dew Point: 21.7°FDecreased 1.1°Fsince last hour.
  • Relative Humidity: 67%Decreased 1.0% since last hour.
  • Wind: Wind from WNW WNW 1 mph, 10-min avg: 2 mph, gust: 9 mph
  • Barometer: 29.94 inRising 0.03  inHg/hr Rising Slowly
  • Snow Today: 0.0 in
  •   
Southeast Middlesex County, MA - Wind Advisory
 - SEE ALL NEARBY ALERTS -

Area Forecast Discussion
for Boston / Norton, MA

        
000
FXUS61 KBOX 131203
AFDBOX

Area Forecast Discussion
National Weather Service Boston/Norton MA
703 AM EST Thu Feb 13 2025

.SYNOPSIS...
The mix of wintry weather exits this morning then dry, but 
windy and colder weather follows tonight into Friday. Another 
system brings a round of wintry precipitation Saturday night and
Sunday, starting as snow before changing to rain near the coast
and a wintry mix inland. A shot of arctic air follows Monday 
and Tuesday along with gusty winds for Monday.

&&

.NEAR TERM /THROUGH TONIGHT/...
Key Messages...

* A exiting storm system will continue to bring snow changing to a 
  mix of sleet and freezing rain then rain this morning. 

* Drier and windy in the afternoon, increasingly gusty overnight. 

As expected the lackluster DGZ really did a number on our snowfall 
accumulations making for smaller crystals rather than large 
dendrites. As of 4AM the 850 mb warm nose has already made its way 
well into SNE, with snow remaining just north of a Worcester to 
Beverly line and a mix of sleet/freezing rain and plain rain 
elsewhere. Temperatures at the surface are in the 33-37F range south 
and east of the I-95 corridor and areas further north will slowly 
continue to flip to rain as the warm nose advances further. A Winter 
Weather Advisory continues for the interior where it will be a 
slick and icy commute. 

Dry slot moves in by mid afternoon as the low exits into the 
maritimes and winds swing around to the NW. This will allow the 
remaining shallow cold air to be scoured out leading to highs in the 
upper 30s (high terrain) to upper 40s (south coast). Mid level cold 
advection will create a well mixed boundary layer going into the 
afternoon and overnight hours just as a 45 to 55 kt westerly LLJ 
moves over SNE. This will make for breezy conditions in the 
afternoon over the southeast coast, expanding to the rest of the 
region in the late evening and overnight. Model soundings show 
mixing up to 850 mb, tapping into that LLJ and mixing down gusts as 
strong as 50 mph. The highest confidence in these gusts 
materializing is over western and central MA where a Wind Advisory 
is in effect. Cold NW winds lead to lows in the teens and 20s, but 
it will feel more like single digits and teens thanks to the wind.

&&

.SHORT TERM /FRIDAY/...
Key Messages...

* Period of strong winds lingers into Friday morning, diminishing in 
  the afternoon and evening. 

After a cold night temperatures rebound into the upper 20s and low 
30s but the wind sticks around, making it colder. The windiest part 
of the day will be the morning, as the LLJ moves offshore by 
afternoon and the pressure gradient relaxes.

&&

.LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/...
Key Messages: 

* Next system arrives Saturday afternoon bringing snow to start 
  followed by a transition to ice and rain by mid-morning Sunday.

* Exact snow amounts uncertain. At least minor accumulations (1-3") 
  for northern CT and much of MA.  

* Windy conditions Monday. Below normal temperatures early next 
  week. 

Details: 

Friday Night: 

High pressure remains in place Friday night with increasing cloud 
cover toward sunrise. The cold airmass in place will support a 
chillier night with low temperatures dropping into the teens with 
some single digits possible for the higher elevation areas across 
the MA interior. 

Weekend: 

The pattern becomes active again for the weekend as a southern 
stream shortwave trough ejects northward ahead of a deep upper level 
trough. Ensemble means track a surface low lifting NE across the 
region by the end of the weekend. Plenty of support for widespread 
precipitation with this system with a plume of above normal moisture 
with precipitable water values 300% of normal paired with synoptic 
ascent. With model guidance still struggling to pin down the track 
of the storm, precipitation type will be the main forecast challenge.

There is good agreement among model guidance with a cool airmass in 
place ahead of the system Saturday. This will help prime the 
environment for snowfall with the arrival of the precipitation 
Saturday afternoon. Snow likely continues through the evening with 
pockets of moderate snow possible in the evening as mid-level warm 
front pushes northward. As mentioned earlier, the main complication 
will be precip-type. As warm air moves in aloft Saturday night, it 
will slowly warm the vertical column. This will bring us the classic 
change-over to a wintry mix. As a result of track/timing differences 
among guidance, the timing of the warm air is still uncertain which 
will factor into snow amounts.  

Despite disparities between guidance, there is a high chance for 
minor accumulations (1-3") for northern CT and most of MA. There are 
solutions that favor potent probability for higher amounts for 
> 6" that have been reflected in the ensemble probabilities 
ranging from 30-60% north of the Mass Pike. Some locally higher 
probs confined to the north border and higher terrain across the
interior. What we can take from this right now is that areas 
north of the MA Pike have the highest potential for Advisory 
level amounts while others it is less certain due to the timing 
of the warm air and transition to mixed precip. So for now, 1-5"
is a realistic range. By mid-morning Sunday, warm air will be 
in full force changing things to rain. Higher elevation areas 
across the interior such as the Berkshires and Worcester hills 
may lag in the change-over to rain Sunday morning with shallow 
cool air slower to erode out.

A cold front with strong CAA behind it pushes through on the 
backside of the system Sunday evening accompanied by gusty west 
winds. Model guidance hints at wrap around moisture with the exiting 
system. This may support lingering rain/snow showers Sunday evening. 

Early Next Week: 

The ECMWF EFI highlights another period of anomalously high winds 
for Monday. With strong CAA advection and a moderate LLJ overhead, 
the potential for stronger gusts should be supported. This will 
support a windy day with potential for Advisory/near Advisory winds 
for the Berkshires and Worcester Hills (45 mph+). Otherwise looking 
at gusts 25-40 mph across other spots. 

Ensemble 850mb temperature anomalies show a well below normal 
airmass overhead early next week. This will set the stage for below 
normal temperatures with highs in the 20s by Tuesday. By Wednesday 
there are some signs of upper level heights becoming more zonal 
which should help moderate temperatures back into the low 30s.

&&

.AVIATION /12Z THURSDAY THROUGH MONDAY/...
Forecast Confidence Levels:

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

12z TAF Update...

Today...High Confidence.

IFR-LIFR ceilings in ice/rain. All terminals eventually change 
to plain rain by mid-late morning although can't rule out some 
light icing persisting in the highest terrain until lunch time 
(northern Worcester Hills/Berkshires). Bulk of the steady 
precipitation will be over by early afternoon.

E wind gusts of 25 to 35 knots developing toward daybreak along
the immediate coast and between 15 and 25 knots across the 
interior. The winds will then shift to the SW late afternoon 
with gusts of 25-35 knots towards the Cape/Islands...but much 
weaker across the interior. We do expect gusty southwest winds 
to develop across the interior though by early evening. Could 
see a period of wind shear in the afternoon to early evening 
period mainly for the Cape and Island, but can't rule out 
BOS/PVD. 

Tonight...High Confidence

Gradually improvements in ceilings early evening with VFR
conditions by 03z. Gusty west winds with gusts 25-35 kts and
localized up to 40 kts for ORH and further west across the
Berkshires. 
 
KBOS TAF...High Confidence.

KBDL TAF...Moderate confidence in timing. The light freezing 
rain should change to plain rain in the 12z to 14z time range. 

Outlook /Friday Night through Monday/...

Friday Night: VFR. Windy with local gusts up to 30 kt. 

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

Saturday Night: Mainly IFR, with local MVFR possible. Breezy.
SN, RA, PL, FZRA.

Sunday: Mainly IFR, with areas MVFR possible. Windy with local
gusts up to 30 kt. RA, FZRA.

Sunday Night: Mainly VFR, with local MVFR possible. Windy with
gusts up to 35 kt. RA likely, chance SN.

Washingtons Birthday: VFR. Strong winds with local gusts up to
40 kt.

&&

.MARINE...
Forecaster Confidence Levels:

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

Through Friday...High Confidence.

Areas of rain will reduce vsbys for mariners at times this
morning as a low passes over the northern waters. This system
will bring increasingly gusty S then SW and W winds through the
day, gusting to 30 kts by this afternoon with seas 6-8 ft.
Overnight winds and seas increase further with gusts as high as
40 kts and seas 8-10 ft. Friday winds and seas remain elevated
by will slowly decrease throughout the day as high pressure
approaches. 

Outlook /Friday Night through Monday/...

Friday Night: Low risk for Small Craft Advisory winds with
gusts up to 30 kt. Local rough seas. 

Saturday: Winds less than 25 kt. Chance of snow. 

Saturday Night: Winds less than 25 kt. Seas locally approaching
5 ft. Rain, snow. Local visibility 1 nm or less.

Sunday: Strong winds with gusts up to 30 kt. Rough seas up to
14 ft. Rain. Areas of visibility 1 to 3 nm.

Sunday Night: Strong winds with gusts up to 35 kt. Rough seas
up to 14 ft. Chance of rain. 

Washingtons Birthday: Moderate risk for gale force winds with
gusts up to 40 kt. Rough seas up to 13 ft.

&&

.BOX WATCHES/WARNINGS/ADVISORIES...
CT...Winter Weather Advisory until 10 AM EST this morning for 
     CTZ002>004.
MA...Winter Weather Advisory until 10 AM EST this morning for 
     MAZ002>006-008>012-026.
     Wind Advisory from 7 PM this evening to 1 PM EST Friday for 
     MAZ002>004-008>012-026.
RI...Winter Weather Advisory until 10 AM EST this morning for 
     RIZ001.
MARINE...Gale Warning from 10 PM this evening to 1 PM EST Friday for 
     ANZ230.
     Gale Warning from 7 PM this evening to 7 PM EST Friday for 
     ANZ231-251.
     Gale Warning from 7 PM this evening to 1 PM EST Friday for 
     ANZ232>235-237-255-256.
     Gale Warning from 10 PM this evening to 7 AM EST Friday for 
     ANZ236.
     Gale Warning from 7 PM this evening to 10 PM EST Friday for 
     ANZ250-254.

&&

$$

SYNOPSIS...BW/Mensch
NEAR TERM...BW
SHORT TERM...BW
LONG TERM...Mensch
AVIATION...BW/Mensch
MARINE...BW/Mensch
      

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