Old Res Weather

Lexington, Massachusetts, USA

35°F

2/16/2025 7:17pm

Lexington Conditions: Overcast
Temperature: 35.1°F / 1.7°C
Dew Point: 32.4°F
Relative Humidity: 90%
Wind: Calm, 10-min avg: Calm, gust: None
Barometer: 29.00 in Falling Slowly
Visibility: 10 miles
Rain Today: 0.01 in
UV Index: $VPuv None

Area Forecast Discussion
for Boston / Norton, MA

        
000
FXUS61 KBOX 292341
AFDBOX

Area Forecast Discussion
National Weather Service Boston/Norton MA
741 PM EDT Wed Apr 29 2026

.WHAT HAS CHANGED...
No significant changes.

&&

.KEY MESSAGES...

- Coastal clouds, drizzle, and fog give way to widespread
  beneficial rainfall tonight into Thursday.

- Cooler and mainly dry this weekend then milder next week with
  a few showers.

&&

.DISCUSSION...
KEY MESSAGE 1...Coastal clouds, drizzle, and fog give way to 
widespread beneficial rainfall tonight into Thursday.

Low cloud deck finally eroded a bit thanks to daytime heating 
and was confined to areas near the immediate coast, although 
we're seeing some substantial breaks in cloud cover especially 
near Cape Cod and Islands. Cloud deck should begin to expand 
westward again this evening as we lose daytime heating and 
boundary layer cools, and deepening marine layer should promote
patchy fog and drizzle along coast. Farther inland, mostly clear
skies will persist with increasing mid and high clouds early 
tonight.

We're still looking at two areas of showers tonight into Thursday. 
First is later this afternoon and evening across eastern MA in 
association with surface trough from offshore low. Showers will then 
become more widespread later tonight into Thursday morning as 
we come under broad larger scale lift ahead of upper trough (as 
seen in model Q-vector fields) and primary low tracking through 
the St. Lawrence Valley. Secondary low tracking from mid 
Atlantic has trended weaker since yesterday so between that and 
the speed of the system overall rainfall will be less, on the 
order of around 0.5" for most, but still much needed given 
recent rainfall departures.

Guidance does show some marginal instability on the edge of the dry 
slot that lifts through southern New England Thursday morning, 
focused near Cape Cod and Islands, but moreso offshore. It's 
possible we see some additional showers or even a thunderstorm 
pop up in those areas but that is conditional on seeing better 
instability.


KEY MESSAGE 2...Cooler and mainly dry this weekend then turning 
milder early next week with a few showers.

Amplified pattern over the weekend should feature a building ridge 
of high pressure over central Canada which traps a closed upper low 
over southern Ontario. As mentioned before, southern New England 
should be far enough removed from coldest air aloft to keep us 
mostly dry, especially given W/NW flow, but pattern certainly favors 
diurnal clouds and perhaps a few afternoon sprinkles over weekend.

We're also watching a weak low also passing offshore that could come 
close enough to bring a few showers to parts of eastern MA and RI 
later Saturday into Sunday, but right now any rainfall looks to be 
fairly light and may end up being more focused near Cape Cod and the 
Islands or even offshore.

Pattern relaxes a bit early next week as closed low lifts farther 
north, but we remain under broad cyclonic flow aloft. Eventually 
longer range guidance shows closed low setting up near upper Great 
Lakes, putting us in SW flow aloft. This could end up bringing
more moisture into region by Tuesday/Wednesday as weak front
approaches resulting in scattered showers. Temperatures should
return to more typical levels for early May however.

&&

.AVIATION /00Z THURSDAY THROUGH MONDAY/...
Forecaster Confidence Levels...

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

00z TAF Update: Moderate confidence due to timing of flight 
categories.

MVFR/IFR closer to coast will become IFR this evening, roughly as 
far west as KORH/KIJD with VFR conditions prevailing farther to the 
west. Scattered -SHRA possible later this afternoon and evening in 
eastern MA before showers become more widespread overnight with
IFR ceilings/visibilities. Showers come to an end around midday
Thu with gradual improvement to MVFR ceilings, and possibly VFR
later in day with the exception of Cape Cod and Islands. 

KBOS Terminal...Moderate confidence. Return of IFR/LIFR could be
a few hours too fast.

KBDL Terminal...High confidence in TAF.

Outlook /Thursday Night through Monday/...

Friday: VFR. Breezy. 

Friday Night: VFR. 

Saturday: VFR. Slight chance SHRA.

Saturday Night: VFR. Chance SHRA.

Sunday: VFR. Breezy. Slight chance SHRA.

Sunday Night: VFR. 

Monday: VFR. Breezy.

&&

.MARINE...
Forecaster Confidence Levels...

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

High confidence through the end of the week.

Pressure gradient between slow-moving low pressure SE of the 40/70 
benchmark and high pressure over the Canadian Maritimes keeps E/NE 
winds in play through the end of the week. 

Main issue will be the long fetch of NE winds resulting in rough 
seas of 5 to 8 feet on outer waters through Thu where SCA remains 
posted. Areas of fog will persist through Thu along with showers, 
especially later tonight through early Thu afternoon.

Outlook /Thursday Night through Monday/...

Friday through Friday Night: Winds less than 25 kt. Seas up to
5 ft. 

Saturday: Winds less than 25 kt. Areas of seas approaching
5 ft. Chance of rain showers. 

Saturday Night: Winds less than 25 kt. Seas locally approaching
5 ft. Chance of rain showers. 

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

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

Monday: Winds less than 25 kt. Seas up to 5 ft.

&&

.BOX WATCHES/WARNINGS/ADVISORIES...
CT...None.
MA...None.
RI...None.
MARINE...Small Craft Advisory until 8 AM EDT Friday for ANZ250-254>256.

&&

$$

DISCUSSION...JWD - Last
AVIATION...Dooley/JWD
MARINE...JWD