Lexington Weather

Lexington, Massachusetts, USA

37°F
3/29/2024 9:59am 
  • Lexington Conditions: Light rain, Overcast
  • Temperature: 37.0°F / 2.8°CColder 0.2°F than last hour.
  • Dew Point: 36.0°FDecreased 0.1°Fsince last hour.
  • Relative Humidity: 96
  • Wind: Wind from NNW NNW 4 mph, 10-min avg: 2 mph, gust: 8 mph
  • Barometer: 29.55 in Steady
  • Visibility: 8 miles
  • Rain Today: 0.31 in
  •   

Area Forecast Discussion
for Boston / Norton, MA

        
000
FXUS61 KBOX 270551
AFDBOX

Area Forecast Discussion
National Weather Service Boston/Norton MA
151 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 /THROUGH TODAY/...

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 /TONIGHT 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

* Heavy precipitation late week may lead to an elevated risk for 
  flooding across RI and southeastern MA

* Trending drier with near normal temperatures this weekend

Looking like southern New England is heading into a prolonged
period of unsettled weather late this week. Significant ensemble 
signals in the NAEFS, with standardized anomalies of 3-4
standard deviations. We're looking at quite a bit of moisture
and lift sometime from Thursday into Friday a a coastal low
pressure moves by to our east. Given this storm track, the
greatest risk for rainfall will be across the Cape and islands, 
but there should be at least some rainfall across most of
southern New England during this time. There is potential for
another 1-2 inches of rainfall in our region, which will need to 
be monitored with area waterways already running high from the 
rainfall this past Saturday. Should confidence in significant 
rainfall continue to increase, Flood Watch headlines may be 
needed for portions of southern New England.

Still thinking this weekend remains mainly dry, but the picture
is not as clear as it once was. A low pressure should move into
the Maritimes from east of New England by Saturday. The question 
then becomes where exactly will the cold front of this low
pressure be. At this time, thinking it stalls just to the south 
of New England. With another low pressure projected to develop 
over the central USA at this time, providing another mechanism 
to keep this front nearby. This low pressure itself is projected
to pass by to our south on Sunday, but not far enough south to 
prevent some clouds from reaching our region. Saturday looks to 
be the windier of the two days, as some cooler air arrives on 
the back side of the departing low pressure.

Weak high pressure should then continue into Monday, before
another low pressure possibly arrives towards next Tuesday.

Near to slightly above normal temperatures anticipated through
this portion of the forecast.

&&

.AVIATION /06Z 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. Windy with local
gusts up to 30 kt. Chance RA.

Friday: VFR. Windy with gusts up to 35 kt. Chance RA.

Friday Night: VFR. Windy with gusts up to 35 kt. 

Saturday: VFR. Windy with gusts up to 30 kt.

&&

.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/...

Wednesday Night: Winds less than 25 kt. Local rough seas. Rain
likely, patchy fog. Visibility 1 to 3 nm.

Thursday: Winds less than 25 kt. Seas up to 5 ft. Rain. Local
visibility 1 to 3 nm.

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

Friday: Strong winds with gusts up to 30 kt. Rough seas up to
9 ft. Chance of rain. 

Friday Night: Low risk for gale force winds with gusts up to
35 kt. Rough seas up to 8 ft. Slight chance of rain. 

Saturday: Low risk for gale force winds with gusts up to 35 kt.
Areas of rough seas.

&&

.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...Belk
AVIATION...Belk/Nocera
MARINE...Belk/Nocera
      

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