521
FXUS61 KBOX 261106
AFDBOX

Area Forecast Discussion
National Weather Service Boston/Norton MA
706 AM EDT Sat Jul 26 2025

.SYNOPSIS...
Showers and areas of severe thunderstorms continue this
afternoon with a cold front. Cooler and mainly dry Saturday
with showers and thunderstorms returning for Sunday. Outlook for
early next week shows summerlike warmth and humidity, with
generally dry weather for the majority of the time. Showers and
thunderstorms return for Sunday. Outlook for early next week
shows summerlike warmth and humidity, with generally dry weather
interrupted by a few shots at scattered showers and
thunderstorms, mainly Tuesday and late Wednesday into Thursday.
Trending drier and cooler Friday into the weekend.

&&

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

Key Messages:

* Dry conditions and cooler today
* Some near surface smoke/haze especially this morning

Details:

We added some near surface smoke and haze to the grids this
morning as a result of distant Canadian Wildfires. The latest
HRRR/RAP indicate that the worst of the smoke will be this
morning with gradual improvements later today and especially by
this evening.

Otherwise...behind Friday`s front, high pressure shifts east
over the region bringing in a dry airmass and generally light
easterly component flow. Temperatures will be considerably
cooler in the post-frontal airmass with 850mb temperatures 5-8
degrees cooler than Friday. This will equate to high
temperatures in the 80s across the interior with some upper 80s
possible in the valleys. E/SE onshore flow will keep the
immediate coastal areas cooler today with highs in the upper 70s
to around 80.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM SUNDAY/...

Key Messages:

* Showers and a few embedded thunderstorms return on Sunday. Severe
  weather is not expected at this time.

* Pockets of localized heavier rainfall possible in any embedded
  thunderstorms.


Tonight:

A warm front approaches the region tonight ahead of our next
approaching system. This will increase cloud cover as the night
wears on. Low temperatures will be seasonable in the mid 60s.

Sunday:

Unsettled weather returns for Sunday as a weak shortwave trough
moves through the quasi-zonal mid-level flow. Weak synoptic ascent
will be accompanied by a plume of above normal moisture (150-170% of
normal) to support increased cloudiness and precipitation. Given the
limited upper level support, instability will be marginal/limited
which reduce the risk for severe weather. Given marginal elevated
instability, can`t rule out a few embedded convective showers or
thunderstorms.

For timing, HREF guidance shows the most likely window for rain
arriving between 6AM and 11AM (little later for Cape) spreading
from west to east. Can`t rule out scattered showers before the
main bulk of precipitation arrives which has been hinted at by
individual CAMs, but with varying timing. High resolution
guidance shows precipitation exiting mid-late afternoon with
some showers lingering over the Cape/Islands in the early
evening. The presence of above normal moisture and marginal
instability does raise some risk for pockets of locally heavy
rainfall in any embedded thunderstorms. Model guidance hints at
better forcing mainly north of southern New England; however, it
may position close enough to bring additional lift/instability
for more moderate to heavy rainfall. HREF PMM means highlight
western MA in particular for higher amounts of rainfall with
some isolated 1-1.5" bullseyes. Overall, we`ll interpret this
as a general signal for seeing a higher probability for locally
heavier amounts. Across ensemble guidance, means show a range of
QPF from 0.10"-1.0" with again the higher range of amounts
across western MA. Rain and cloudiness will result in a cooler
day with highs in the

&&

.LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/...

Key Messages...

* Showers and a few embedded thunderstorms return on Sunday.
 Severe weather is not expected at this time.

* Temps warm up into the 90s through mid week but cooler weather
  arrives late week into the weekend.

* Mostly dry this week with a chance of showers and t-storms around
  Tuesday and late Wed/Thu.

A mid-level ridge pushes east into the region Monday which will
start the week off dry. 850mb temperatures warm back up to around 18-
20C again trending temperatures back up from the weekend. Highs will
likely range in the upper 80s to low 90s for the interior while the
coastal areas will stay cooler in the low to mid 80s from sea
breezes.

Ensemble guidance shows anomalous temperatures sticking around
Tuesday and potentially into Wednesday to some extent. Tuesday, a
weak shortwave trough moves through the flow aloft which will bring
isolated to scattered showers and thunderstorms in the afternoon.
Ensemble guidance shows a more substantial wave moving through in
the Weds-Thurs timeframe. Still uncertainty in the details such as
timing, precipitation chances/amounts. What makes this wave also
more substantial aside from increased precipitation chances will be
the cooler airmass pushing in behind it. This will break the above
normal temperatures from earlier in the week. Ensemble guidance
shows good agreement with a transition to even below normal
temperatures by Friday. This airmass will feel almost Fall-like! We
are a little far away for any tinier details, but trends show
potential for highs in the 70s by Friday.

&&

.AVIATION /11Z SATURDAY THROUGH WEDNESDAY/...
Forecaster Confidence Levels...

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

06Z Update:

Through 12z: High Confidence.

Ceilings are generally VFR. Still can`t rule out a brief period
of BR for the Cape and Islands early this morning as there is
still some residual moisture/clouds lingering. Dry air should
clear any residual patchy fog by 12z.

Saturday: High Confidence.

VFR with upper level clouds arriving throughout the afternoon.
Winds start NNE this morning then turning more easterly in the
early-late afternoon. Speeds 5-8 kts for the interior and 6-12
kts closer to the coast. There may be a brief period of light
VRB winds at the interior terminals (BDL, BAF, ORH) early
afternoon.


Saturday Night: High Confidence

VFR. Light SE at 5-8 kts winds early evening become light SSW by
midnight. Rain should begin to move in across southern New
England from west to east after 08z. Mid-level ceilings push
across region ahead of the showers.

Sunday:

Mainly mix of low end VFR to MVFR as rain moves across southern
New England on Sunday. S/SSW winds 8-13 kts.

KBOS terminal...High confidence.

KBDL terminal...High confidence.

Outlook /Sunday Night through Wednesday/...

Sunday Night: Mainly VFR, with local MVFR possible. Chance
SHRA.

Monday through Tuesday Night: VFR.

Wednesday: VFR. Slight chance SHRA, slight chance TSRA.

&&

.MARINE...
Forecaster Confidence Levels...

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


Through Sunday...High Confidence.

NNE/NE winds at 10-15 kts this morning, closer to 20 kts for the
southern waters. Gusts around 25 kts this morning. This should
be short-lived as wind speeds trend downward after 12z becoming
light E in the afternoon 8-12 kts. Winds veer SSW Saturday
evening. Rain expected Sunday with S/SSW winds 10-15 kts. Gusts
up to 20 kts for the norther outer water.

Outlook /Sunday Night through Wednesday/...

Sunday Night: Winds less than 25 kt. Chance of rain showers,
slight chance of thunderstorms.

Monday through Wednesday: Winds less than 25 kt.

&&

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

&&

$$

SYNOPSIS...Mensch
NEAR TERM...Frank/Mensch
SHORT TERM...Mensch
LONG TERM...Mensch
AVIATION...Mensch
MARINE...Mensch