Old Res Weather

Area Forecast Discussion
for Boston / Norton, MA

        
000
FXUS61 KBOX 250658
AFDBOX

Area Forecast Discussion
National Weather Service Boston/Norton MA
258 AM EDT Sat Apr 25 2026

.WHAT HAS CHANGED...
Increases to rain chances and northeast wind speeds and gusts 
for Sunday into Monday for southeast New England. While these 
changes were minor, more significant increases could be needed 
pending the track of coastal low pressure to Southern New 
England. 

&&

.KEY MESSAGES...

- Increasing cloudiness today and generally dry with cooling 
  onshore breezes, although light rain showers develop late 
  today and tonight in western MA into portions of CT and 
  southern RI. 

- Coastal low pressure just to our south brings cloudy and cool
  weather, northeast breezes and periods of rain showers to 
  southeast New England Sunday, possibly into Monday.

- Dry weather with onshore breezes resume early to middle of
  next week with a warming trend to temps, before weather turns
  more unsettled late in the week. 

&&

.DISCUSSION...
KEY MESSAGE 1...Increasing cloudiness today with cooling onshore 
breezes, although light rain showers develop late today and 
especially tonight for western MA and portions of CT and southern 
RI. 

Sfc ridge in place across most of Southern New England will supply 
another round of modest onshore flow/seabreezes today, with cool 
temperatures in part from a upper-level low parked over the Canadian 
Maritimes. To our west is a stream of mid to high level moisture 
across western NY, which will be advancing across our area through 
today. Expect increasing cloudiness toward an overcast look by this 
afternoon, although for the vast majority of Southern New England, 
that "overcast" is really a pretty extensive canopy of mid to high 
cloud cover. With mid to high clouds and onshore flow, I kept highs 
on the cooler end of guidance in the mid/upper 40s for eastern MA 
and the South Coast, and lower to mid 50s further into the interior.

Although much of the area is dry today/tonight, the exception is in 
far western MA and adjacent Hartford County in CT, and eventually 
into Tolland County RI and southern RI late tonight. Showers 
associated with an initially weak mid-level shortwave trough over MI 
end up shifting ESE today, and some of those showers should be able 
to make it into western MA/Hartford County area late in the day 
(shortly before sundown), then expand ESE toward southern RI 
tonight. The eastern and northern extent of these showers should be 
stunted by northwesterly confluent mid-level flow and the drier air 
in place; most BUFKIT profiles show a pretty robust plume of 
dry air below 850 mb in central/eastern MA and northern RI. The 
NAM still remains a more bullish outlier on QPF, and even though
the GFS did tick upward some, some of that QPF will be lost to 
saturate the profile. Offering periods of light rain from about 
Westfield to Willimantic south and west thru midnight, then 
expanding southeast towards southern RI/Newport area overnight. 
Possible that some of that could mix with wet snowflakes in the 
terrain in Tolland County but really not of much impact. High 
res guidance also shows a rather sharp precip cutoff, far more 
so than the coarser-res global models show and that probably is 
what transpires. This then sets us up for a lower-confidence 
forecast as we head into Sunday and Monday, to be addressed in 
the next Key Message. 

KEY MESSAGE 2...Coastal low pressure just to our south brings cloudy 
and cool weather, northeast breezes and periods of rain showers to 
southeast New England Sunday, possibly into Monday.

Low pressure south of Long Island Sunday morning, on the southern 
periphery of the high pressure in place over New England, should 
still favor at least overcast with best chance for rain along the 
South Coast, Cape and Islands, to go along with enhanced NE winds. 
Devil's in the details and the main issue is how far north and how 
quickly will this low pressure get to at least southeast New England 
for Sunday and possibly into Monday. Seemingly key in that evolution 
is how quickly will the trough over MI today become entrained with 
the circulation over Atlantic Canada and close off. The NAM, SREF 
and to a more limited extent the 12z ECMWF show the trough closing 
off soonest, producing a slow-moving gale low south of Nantucket, 
which then slowly meanders NNE into Monday. Were this to verify, 
much of southeast New England would see a chilly, raw and wet Sunday 
and Monday with periods of rain and NE gusts to near gale force 
(e.g. NAM shows 950 mb NE winds 55-60 kt). The risk for rain in that 
outcome would also extend as far north as the Mass Pike, and 
especially eastern MA. Though I think it's too early to outright 
dismiss this, it doesn't have much support from the 
GFS/Canadian/more recent 00z ECMWF camp, which closes off the mid-
level shortwave too late to a more offshore solution, keeping 
lighter rain showers to the coastal waters, Martha's Vineyard, 
Nantucket and Cape Cod with NE breezes, with mostly cloudy but 
generally dry conditions elsewhere for Sunday into Monday. Cluster 
analyses also suggest the NAM solution is more of an outlier. Will 
weight the forecast closer to the GFS/Canadian more offshore idea, 
but still shows chance to borderline likely PoP and NE winds 
increasing Sunday night into Monday for southeast New England. If 
other guidance were to come on board with the NAM in subsequent 
guidance, then the potential for more substantial forecast changes 
would be in the cards. Astro tides are decreasing so really no risk 
for coastal flooding. Highs in the 40s to lower-mid 50s Sunday, 
coolest southeast New England, and in the 50s to lower 60s for 
Monday, though in the lower 50s for eastern MA with NE breezes.

KEY MESSAGE 3...Dry weather with onshore breezes resume early to 
middle of next week with a warming trend to temps, before weather 
turns more unsettled late in the week. 

High pressure then reasserts itself once the coastal low pulls away 
either Monday or Tuesday - viewed as more likely Monday. This brings 
what should be nice weather with onshore breezes and temperatures 
gradually modifying, although still slightly cooler than normal. Our 
weather pattern then turns more unsettled for mid to late in the 
week, with a possible risk for coastal cloudiness/rain showers
Wednesday, and then troughing and a cold front around 
Thursday/Friday.

&&

.AVIATION /06Z SATURDAY THROUGH WEDNESDAY/...
Forecaster Confidence Levels...

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

06z TAF Update: 

Today and Tonight: High confidence. 

VFR, increasing coverage of mid to high clouds. Ceilings start
to lower to lower-end VFR/MVFR levels near BDL around 22-00z
with rain showers. VFR-visby rain showers and MVFR ceilings then
expand southeast to near PVD overnight. NE winds 5-10 kt 
shifting to SE late morning into the afternoon, then becoming 
light southerly (calm at times) early tonight before returning 
back to NE 5-10 kt toward daybreak Sunday.

Sunday and Sunday Night: High confidence for most, but low to
moderate confidence for the Cape and Islands. 

BKN/OVC VFR for most, with NE winds 5-10 kt. Lowest
ceilings/categories (MVFR levels) and stronger NE winds around
10-15 kt for the Cape and Islands, to go along with periods of 
showers as low pressure passes to our south. If the low pressure
were to track closer to Southern New England's waters, then
ceilings would trend closer to IFR/LIFR, MVFR visby rain and NE
winds in the 20 kt range for the Cape and Islands, with MVFR
ceilings northward to the I-95 corridor, but this is viewed as
unlikely.

KBOS Terminal...High confidence in TAF. VFR through the period. 
NE winds 5-10 kt trend to ESE by late morning, then shifting to 
light southerly (calm at times?) late tonight before returning 
back to NE overnight.

KBDL Terminal...Moderate confidence in TAF. VFR through at least
late this afternoon. Ceilings lower to MVFR ranges with VFR
visby rain showers 23-01z, which continue through 12z Sunday.
ESE winds trend light southerly tonight, then return to ENE
winds overnight. 

Outlook /Sunday through Wednesday/...

Sunday: Mainly VFR, with local MVFR possible. Slight chance RA.

Sunday Night through Monday: VFR. Breezy. Slight chance SHRA.

Monday Night through Tuesday: VFR. Breezy. 

Tuesday Night through Wednesday: Mainly VFR, with local MVFR
possible. Chance SHRA.

&&

.MARINE...
Forecaster Confidence Levels...

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

Today and Tonight: High confidence. 

Winds and seas are below SCA criterion through tonight, with
E/SE winds around 10-15 kt and seas 3 ft or less, building to
around 4 ft on southern waters. Dry weather today, although a
risk for showers on the southern waters tonight. 

Sunday and Sunday Night: Moderate confidence. 

Coastal low pressure passes over the southern waters Sunday into
Sunday night. Expect increasing northeast winds to around 20-25
kt and building seas, which could warrant SCAs on the southern 
waters if the low pressure passes closer to Southern New 
England's waters. NE winds around 10-20 kt northeast waters. 
Though it is unlikely, a period of stronger northeast winds 
possibly into the 30 kt range could develop Sunday night 
southeast of Cape Cod. Rain showers southern waters, but mainly 
dry eastern waters.

Outlook /Sunday through Wednesday/...

Sunday: Winds less than 25 kt. Chance of rain. 

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

Monday: Low risk for Small Craft Advisory winds with gusts up
to 25 kt. Areas of seas approaching 5 ft. Chance of rain
showers. 

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

Tuesday: Winds less than 25 kt. Local rough seas. Slight chance
of rain showers. 

Tuesday Night: Winds less than 25 kt. Areas of rough seas.
Slight chance of rain showers. 

Wednesday: Winds less than 25 kt. Rough seas up to 8 ft. Chance
of rain showers. 

&&

.BOX WATCHES/WARNINGS/ADVISORIES...
CT...None.
MA...None.
RI...None.
MARINE...None.

&&

$$

DISCUSSION...Loconto
AVIATION...Loconto
MARINE...Loconto