Lexington Weather

Area Forecast Discussion
for Boston / Norton, MA

        
000
FXUS61 KBOX 051832
AFDBOX

Area Forecast Discussion
National Weather Service Boston/Norton MA
232 PM EDT Sun Apr 5 2026

.WHAT HAS CHANGED...
No significant changes.

&&

.KEY MESSAGES...

- Rain showers with brief downpours ending early tonight, then 
  decreasing cloudiness, falling temperatures and increasing 
  westerly winds through the rest of tonight.

- Mostly sunny, cool and blustery Monday. Then increasing 
  cloudiness into the afternoon and perhaps isolated rain or 
  snow showers late in the day into Monday night. 

- Mostly dry and cool to start the week with some lingering
  showers not ruled out entirely for Tuesday.

- Temperatures increase through the second half of next week and
  conditions remain dry.

&&

.DISCUSSION...
KEY MESSAGE 1...Rain showers with brief downpours ending early 
tonight, then decreasing cloudiness, falling temperatures and 
increasing westerly winds through the rest of tonight.

After a cloudy, cool and dreary Sunday with mist/fog around, 
light to at times moderate rain showers are developing in an 
elevated-PWAT environment (around 1.2"). This is in association 
with a cold front, which as of early this afternoon was just 
approaching the Berkshires and Litchfield Hills. Rain showers 
should be rather widespread through late this afternoon as the 
frontal boundary lurches eastward toward the eastern coast; 
though some showers have produced some brief (< 5 min) 
downpours, that should be the extent of it with scant 
instability to work with. The front could be slower to exit Cape
Cod and the Islands until later this evening, but in most 
areas, rain should be coming to an end between 4-8 PM. A few 
areas could see rain totals up to a half-inch, though a quarter 
to third of an inch of rain should be more common - not too 
impactful overall.

Frontal passage will be marked with a westerly windshift around 10 
mph, falling dewpoints through the 20s and 30s and a general 
decrease in cloudiness, although sky conditions could be more partly 
cloudy than fully clear. Lows tonight cool off into the 30s, with 
mid/upper 30s Cape and Islands and temps around freezing in the 
interior higher terrain. 

KEY MESSAGE 2...Mostly sunny, cool and blustery Monday. Then 
increasing cloudiness into the afternoon and perhaps isolated rain 
or snow showers late in the day into Monday night. 

We then become entrenched in general longwave troughiness starting 
Monday, with a prominent cold pool aloft (e.g. 500 mb temps -32C!). 
While the first part of the day is mostly sunny, it will end up 
being chilly and blustery with WNW gusts 25-35 mph with mixing 
heights up to 800 mb. Sunshine offset by cold advection (925 mb 
temps dip to -4C), so offered highs closer to the 40s for most, with 
spot 50 degree readings southeast MA. Will feel cooler than that 
though with the breezes.

Later in the day, the first of a couple fast-moving 500 mb shortwave 
troughs rippling through the broader longwave trough allows for 
increasing cloud cover toward a partly to mostly cloudy look. Most 
models show at least an increase in cloud cover into the afternoon 
and carrying over into the evening - though with a dry/rather mixed 
sub-cloud layer, guidance gives mixed signals if we'd be able to 
wring out any rain or snow showers with some solutions offering 
cloudiness but dry weather while others show some precip and 
possible snow coatings overnight. Current thinking in looking at the 
12z guidance is that the potential is enough such that chance PoPs 
seem warranted for the evening into early Tuesday morning, but 
rain/snow showers probably are isolated enough such that any impact 
would be minimal at worst. With easing winds into the evening, lows 
will be quite chilly with most areas in the upper 20s to around 
freezing, except mid 30s Cape and Islands.

KEY MESSAGE 3...Mostly dry and cool to start the week with some
lingering showers not ruled out entirely for Tuesday.

Generally colder and drier conditions take hold after Monday night 
as surface high pressure starts to take hold and an upper level 
trough settles overhead. A shortwave moving through the region may 
have some lingering showers from Tuesday morning stick around 
through part of the day. Aside from that, drier conditions can be 
expected as dewpoints fall into the 20s across the region (30s over 
the Cape and Islands), and even into the teens for Tuesday night 
into Wednesday. Tuesday night will be noticeably cooler as the 
trough sits overhead and 925 mb temperatures could approach -10C 
(particularly in northern MA, but elsewhere may settle to around 
-8C to -6C) after being just at or below 0C Monday/Monday night. 
Surface lows may dip into the upper teens over the interior and the 
20s to low 30s closer to the coasts. Winds remain mostly W and NW 
Tuesday into early Wednesday in the post-frontal airmass.

KEY MESSAGE 4...Temperatures increase through the second half 
of next week and conditions remain dry.

The general trends from the previous forecast remain consistent.
High pressure moves into the Mid-Atlantic region Wednesday then 
shifts more offshore, which will aid in bringing back SW flow over 
southern New England and keep the region dry. Temperatures will 
improve as the week goes on as the upper level trough moves off to 
the east during the second half of the week. Highs will likely end 
up back in the 50s and 60s. Some uncertainty remains towards the end 
of the week as some ensemble guidance hints at another backdoor 
front moving in Saturday night into Sunday. High pressure moving 
east from just to our north could encourage onshore flow early 
Sunday morning and possibly continuing through the day before it 
shifts further offshore and winds return to SW. We should get more 
clarity on details as we get closer in time.


&&

.AVIATION /18Z SUNDAY THROUGH FRIDAY/...
Forecaster Confidence Levels...

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

18z TAF Update: 

Today: Moderate confidence. 

Still IFR/LIFR due to stratus, mist and areas of fog until cold
frontal passage. Cold front has moved into Southern New England
and is bringing widespread rains, with some brief downpours
possible. Expect rains to come to an end from 21-23z west to
east, though could linger until 02z for the Cape and Islands. 
Post-frontal, expect lifting of ceilings into the SCT- BKN VFR 
range and winds becoming NW and increasing to around 10 kt.

Tonight: High confidence. 

Leftover MVFR ceilings should scatter out to VFR all areas 
early. NW winds increase to 10-15 kt with developing gusts to 25
kt after midnight.

Monday: High confidence.

Mainly VFR; for the interior higher terrain, wouldn't rule out 
some MVFR bases interior high terrain in the aftn as disturbance
aloft approaches and there could be some hit-or-mostly-miss 
sprinkles or flurries. Main concern for aviation is gusty NW 
winds, around 12-17 kt with gusts 25-35 kt, highest at ORH. 

Monday Night: High confidence overall, though moderate on
possible precip chances. 

Disturbance aloft moves through Southern New England Mon night,
which will bring at least SCT-OVC mainly VFR ceilings. Less
clear if we can wring out any precip; if we do, potential for
brief periods of MVFR visby -SHSN. NW winds decrease to 8-12 kt
with gusts in low 20s kt range.

KBOS Terminal...Moderate confidence. IFR, widespread rain at 
MVFR visbys continue thru 23z with arrival of cold front. 
Clearing to VFR likely into the early evening with NW winds 
increasing to around 10-13 kt before midnight, with gusts to 25 
kt toward daybreak Mon.

KBDL Terminal...Moderate confidence. IFR/LIFR, widespread rain 
at MVFR visbys continue thru 22z with arrival of cold front. 
Clearing to VFR likely by sundown, with NW winds increasing to 
around 10-15 kt late evening, with gusts to 25 kt toward 
daybreak Mon.

Outlook /Monday Night through Friday/...

Tuesday: VFR. Breezy. Chance RA.

Tuesday Night through Wednesday: VFR. Breezy. 

Wednesday Night: 

Thursday through Thursday Night: Breezy. 

Friday: 

&&

.MARINE...
Forecaster Confidence Levels...

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

High confidence.

Due to combo of SW winds of 25-30 kt and building wave heights to 
around 5-10 ft (lower 1-2 ft near bays), SCAs continue on all 
waters. We'll gradually be able to peel away at the nearshore SCA 
for tonight - but it seems likely that we'll need to re-hoist SCAs 
for the nearshore waters again on Monday as NW winds increase to 
around 25 kt. Seas will also be slow to decrease into Monday, with 
SCAs on the outer waters continuing into Monday evening. Conditions 
to trend below SCA by Monday evening with NW winds around 15-20 kt 
and seas 4 ft or less. 

Foggy conditions still prevail through early tonight with 
visibilities as low as one-half mile, although widespread rains 
should develop with brief downpours this afternoon into early 
tonight. Expect better visibilities as a cold front moves east of 
the waters as winds turn northwesterly.

Outlook /Monday Night through Friday/...

Tuesday: Winds less than 25 kt. Seas locally approaching 5 ft.
Chance of rain. 

Tuesday Night: Winds less than 25 kt. Areas of seas approaching
5 ft. 

Wednesday through Thursday Night: Winds less than 25 kt. 

Friday: Winds less than 25 kt. Areas of seas approaching 5 ft. 

&&

.BOX WATCHES/WARNINGS/ADVISORIES...
CT...None.
MA...None.
RI...None.
MARINE...Small Craft Advisory until 8 PM EDT this evening for 
     ANZ230>234-236-251.
     Small Craft Advisory until 2 AM EDT Monday for ANZ235-237.
     Small Craft Advisory until 2 PM EDT Monday for ANZ250.
     Small Craft Advisory until 8 PM EDT Monday for ANZ254>256.

&&

$$

DISCUSSION...Loconto/Hrencecin
AVIATION...Loconto/Hrencecin
MARINE...Loconto/Hrencecin