Lexington Weather

Lexington, Massachusetts, USA

41°F
3/29/2024 3:23am 
  • Lexington Conditions: Light rain, Overcast
  • Temperature: 41.4°F / 5.2°CColder 1.4°F than last hour.
  • Dew Point: 40.3°FDecreased 1.8°Fsince last hour.
  • Relative Humidity: 96%Decreased 1.0% since last hour.
  • Wind: Calm, 10-min avg: Calm, gust: 5 mph
  • Barometer: 29.63 in Steady
  • Visibility: 10 miles
  • Rain Today: 0.16 in
  •   
Southeast Middlesex County, MA - Flood Watch
 - SEE ALL NEARBY ALERTS -

Area Forecast Discussion
for Boston / Norton, MA

        
000
FXUS61 KBOX 270735
AFDBOX

Area Forecast Discussion
National Weather Service Boston/Norton MA
335 AM EDT Wed Mar 27 2024

.SYNOPSIS...
Damp and chilly with patchy drizzle and fog Wednesday morning, gives 
way to a period of dry and milder weather from late morning into the 
afternoon.  A frontal wave will bring more widespread rain to the 
region from late Wednesday, through Thursday and possibly lingering 
into early Friday. This additional rainfall may lead to renewed 
flooding concerns. Drying out later Friday and remaining mainly dry 
over the weekend into early next week. Temperatures will be 
seasonable, but remaining breezy at times.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
Key Messages...

* Much milder this afternoon, 15-20 degs warmer than Tue
* Mainly dry weather late morning into early/mid aftn

2 AM update...

1040 mb high over southeast Quebec early this morning wedge down 
into SNE is providing shallow cool air across the region, with NE 
flow and temps in the 30s. Meanwhile, SW flow aloft overriding this 
shallow cool layer is providing WAA spotty light rain/mist/drizzle, 
along with areas of fog.  Thus, another dreary morning on tap. 
However, all models agree on mid level dry air overspreading the 
region this afternoon. This won't result in sunshine (although, some 
brightening in the overcast is possible at times), but a period of 
dry weather is expected from late morning into the afternoon. This 
will be short lived, as deeper moisture and lift arrive later in the 
day in the SW flow aloft. This will result in showers redeveloping 
between 4 pm and 8 pm from west to east. 

As NE winds this morning shift to the SSE this afternoon, combined 
with warm air aloft (925 mb temps warming from +2C 18z Tue to +10C 
Wed at 18z) will result in temps about 15-20 degs warmer than Tue 
along with lighter winds!  This will yield highs in the mid to upper 
50s. If enough breaks of sunshine burn through the clouds, a few 
locations could warm to 60. Dew pts rising from the 30s into the 40s 
will also contribute to the milder conditions.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM THURSDAY/...
Key Messages...

* Widespread rain likely
* Axis of heaviest rain remains uncertain

2 AM update...

Rain becomes more widespread Wed night, as strong subtropical jet 
(up to 140 kt) moves up the eastern seaboard and advects PWATs 
greater than 1 inch across the area. On Thu the axis of highest 
PWATs sets up across southeast MA per ensembles, however strong Fgen 
farther to the west across CT/RI into central MA, resembling a 
winter type system, but ptype all rain for this even. 00z models 
continue to disagree on the exact placement of these features, thus 
axis of heaviest rain remains uncertain. 1-2 inches of rain possible 
with locally up to 3" not out of the question given strong upper jet 
with RRQ over SNE, coupled with strong mid level Fgen and above avg 
PWATs. If 2-3" of rainfall materializes, renewed flooding is 
possible as rivers and streams are running above normal, including 
saturated soils and elevated ground water levels.  Axis of heaviest 
rain will hinge on amplitude of mid/upper level trough and how much 
mid level flow can back along the eastern seaboard. For what
it's worth, 00z HREF has heaviest rain from eastern CT into RI 
and eastern MA. 

Light winds Wed night with mild temps in response to dew pts in the 
40s. Winds remain light on Thu along with temps at or slightly 
milder than normal, with highs in the upper 40s to lower 50s.

&&

.LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/...
Highlights

Long Term

Highlights

* Drying out Friday with seasonable temperatures and windy 
  conditions through Saturday

* Seasonable temperatures and a mix of sun and clouds Sunday and 
  Monday

* Next chance for precip Monday night into Tuesday

Thursday night and Friday

Wet conditions continue Thursday night into Friday as an inverted 
trough axis associated with a coastal-low pressure system progresses 
east off the southern New England coastline. There remains 
uncertainty in how far north and west the inverted trough axis and 
associated area of precipitation reaches in southern New England, 
but steady rain is forecast at least for the east/southeastern areas 
of MA and RI through Friday morning. Precip may linger a bit longer 
over the Cape/Islands as the system continues north and east, but 
we'll begin to see some clearing across the interior zones by Friday 
afternoon. Gusty northwest winds settle in behind the departing low 
and persist into Saturday. 20 to 30 mph gusts will be possible. 
Temperatures will be near to slightly below normal Friday in the 
upper 40s to low 50s.

Friday night and Saturday

A strong low-level jet develops Friday night into Saturday as the 
pressure gradient increases in response to a mid-level ridge 
building in from the west. With a CAA regime in place over southern 
New England Friday night through Saturday, there will be a risk for 
40 to 50 knot winds in the 925 to 850 hPa layer to mix down to the 
surface. Wind headlines may be needed, especially over the higher 
terrain of The Berkshires and Worcester Hills where 40 to 45 mph 
wind gusts will be possible. As low-pressure over The Gulf of Maine 
continues northeast on Saturday afternoon, the gradient should relax 
enough to support diminishing winds Saturday afternoon and evening. 
Nonetheless, 30+ mph wind gusts will be possible for much of the day 
Saturday. Temperatures remain seasonable in the low 50s. 

Sunday through Tuesday

Winds settle down on Sunday but deep northwest flow persists. This 
will support a mix of sun and clouds with seasonable temperatures on 
both Sunday and Monday. Next chance for precipitation will be Monday 
night into Tuesday when a surface low-pressure system is forecast to 
be progressing through The Great Lakes/Midwest region. Details are 
vague at this time, but we'll have more info as we get into the 
weekend.

&&

.AVIATION /08Z WEDNESDAY THROUGH SUNDAY/...
Forecast Confidence Levels:

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

06z update...

Wednesday...high confidence on trends, lower on exact timing 
and details. 

IFR/LIFR in areas of drizzle and fog this morning, slowly lifts
to MVFR/VFR beginning 15z-18z. Mainly dry after 15z, but
scattered showers enter region 20z-00z from west to east. NNE
winds become SSE this afternoon. 

Wednesday night...high confidence. 

MVFR/VFR at 00z lowering to IFR/MVFR as showers overspread the
region tonight. LIFR possible across the hilly terrain of CT and
MA. Light SSE winds. 

Thursday...high confidence. 

Widespread IFR/LIFR in rain, heavy at times possibly across
eastern CT into RI and eastern MA. Light/variable wind becoming
NNE. 

KBOS TAF...High confidence in trends, some uncertainty in exact
timing of details.

KBDL TAF...High confidence in trends, some uncertainty in exact
timing of details. 

Outlook /Thursday Night through Sunday/... 

Thursday Night: MVFR/IFR conditions possible. Breezy. Chance
RA.

Friday: Mainly VFR, with local MVFR possible. Strong winds with
local gusts up to 40 kt. Chance RA.

Friday Night: VFR. Strong winds with gusts up to 45 kt. 

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

Saturday Night: VFR. Breezy. Slight chance RA.

Sunday: VFR. Breezy. 

&&

.MARINE...
Forecaster Confidence Levels:

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

2 AM update...

Key Messages...

* NNE winds finally shift to the SSE Wed afternoon
* Heavy rain possible late Wed night and Thursday

Wednesday...high pressure over southeast Quebec and low pressure off 
the Mid Atlantic coast both weaken today, resulting in diminishing 
winds and direction shifting from NE to SSE this afternoon. Areas of 
drizzle and fog will reduce vsby this morning, then improving this 
afternoon. 

Wed night...weak high pressure remains over the MA/RI waters, 
resulting in light winds. Showers become widespread, limiting vsby. 

Thu...low pressure near the Carolina coast intensifies as it moves 
offshore. This results in light/variable winds becoming light NNE 
across the MA/RI waters. Rain, heavy at times limits vsby. 

Outlook /Thursday Night through Sunday/...

Thursday Night: Low risk for Small Craft Advisory winds with
local gusts up to 30 kt. Seas up to 5 ft. Rain. Local
visibility 1 to 3 nm.

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

Friday Night: Moderate risk for gale force winds with gusts up
to 45 kt. Rough seas up to 10 ft. Slight chance of rain. 

Saturday: Low risk for gale force winds with gusts up to 40 kt.
Areas of rough seas. 

Saturday Night: Moderate risk for Small Craft Advisory winds
with gusts up to 30 kt. Seas up to 5 ft. Slight chance of rain.

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

&&

.BOX WATCHES/WARNINGS/ADVISORIES...
CT...None.
MA...None.
RI...None.
MARINE...Small Craft Advisory until 9 AM EDT this morning for ANZ230.
     Small Craft Advisory until 8 AM EDT Thursday for ANZ250-251-
     254>256.

&&

$$

SYNOPSIS...Nocera
NEAR TERM...Nocera
SHORT TERM...Nocera
LONG TERM...RM
AVIATION...Belk/Nocera
MARINE...Belk/Nocera
      

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