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747
FXUS61 KBOX 030642
AFDBOX

Area Forecast Discussion
National Weather Service Boston/Norton MA
242 AM EDT Thu Jul 3 2025

.SYNOPSIS...
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Hot temperatures today will likely trigger a round of scattered
showers & t-storms between 2 and 10 PM, some of which may be severe.
Quiet for Independence Day heading into the weekend, then heat and
humidity kick up for Sunday and the start of next week. Unsettled
weather may make a return Tuesday into Wednesday.
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&&

.NEAR TERM /THROUGH TONIGHT/...

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Key Messages...

* Hot today with a line of showers and thunderstorms moving through
  from west to east, generally 2 PM to 10 PM. Greatest risk in
  interior MA/CT.

* Drying out and becoming cooler overnight.

Another warm and humid (relative to Friday) day ahead before some
drier and more seasonable air arrives behind a sweeping cold front.
This extends from a low moving through southern Quebec slightly
ahead of a neutrally tilted mid level shortwave. These features will
provide the large scale forcing necessary to take advantage of
existing moisture (dewpoints in the 60s and PWATs of 1.25") and
instability (MUCAPE values toward 1500 J/kg, mid level lapse rates
toward 6.5 c/km). The resulting round of thunderstorms will move
through from west to east ahead of the cold front, generally between
2 and 10 PM. While bulk shear values are better than we saw on
Tuesday (30-40 kts), a limiting factor will be the amount of
moisture and instability available, as well as marginal surface
convergence given winds veering to the W/NW ahead of the mid level
front. Even so, parameters are favorable for at least a few isolated
severe storms, the main threats being damaging winds and large hail.
Storms exit and die down following sunset and loss of diurnal
heating. The post frontal airmass then settles in with dewpoints
dropping into the 50s for most (outside of the south coast). This
allows low temps to be several degrees cooler than the night
previous as well, in the upper 50s/low 60s.
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&&

.SHORT TERM /FRIDAY/...

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Key Messages...

* Dry, sunny, and less humid for Independence Day.

Just in time, a beautiful and more comfortable airmass arrives for
much of the holiday weekend. Friday looks to be sunny and dry under
surface high pressure while the lingering mid level trough and NW
flow will help keep temps more seasonable, in the low to mid 80,
even upper 70s in the high terrain.
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&&

.LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/...

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Key Messages...

* Dry and sunny through the weekend.

* Heat and humidity increase Sunday into early next week.

* Unsettled weather returns around late Mon/Tue but low confidence
  in timing/location details.

The mid level trough finally exits east on Saturday with ridging
building in followed by a weak shortwave early next week. This will
pump up the heat and humidity, really starting on Sunday when the
90s return and continuing until at least Monday. Beyond that there
is some uncertainty owing to the timing of a frontal system which
may bring down temperatures while also introducing a chance for
showers and thunderstorms as early at late Monday. For now, best
chance of unsettled weather looks centered on Tuesday, which would
bring down temperatures.
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&&

.AVIATION /07Z THURSDAY THROUGH MONDAY/...
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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 except moderate confidence
on thunderstorm potential areal coverage as well as timing.

VFR outside of any scattered t-storm threats after 18z into the
first half of the evening. Areal coverage and timing remains
uncertain with this activity...but a few strong t-storms are
possible which may contain locally strong wind gusts and hail
too. The greatest risk is across interior MA and CT terminals.
W winds generally 5-10 knots becoming more NW later tonight.

Independence Day...High confidence.

VFR. NW winds 5-10 kts at most terminals.

KBOS Terminal...High confidence in TAF. Main concern is the risk for
a t-storm in the vicinity of the terminal after 19z/20z into
the early evening hours.

KBDL Terminal...High confidence in TAF. Main concern is the risk for
a t-storm in the vicinity of the terminal after 18z/19z into
the early evening hours.

Outlook /Friday Night through Monday/...

Friday Night through Saturday Night: VFR.

Sunday through Sunday Night: VFR. Breezy.

Monday: VFR. Breezy. Slight chance SHRA, slight chance TSRA.
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&&

.MARINE...
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Forecaster Confidence Levels...

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

Today through Independence Day...High confidence.

Winds/seas stay below small craft advisory thresholds through
Friday. The main concern for mariners will be areas of fog
redeveloping mainly across our southern waters early this morning
which may become locally dense. Winds will generally be in SW
direction on the order of 7-15 knots before switching too a more NW
direction tonight behind the cold front.

Outlook /Friday Night through Monday/...

Friday Night through Saturday Night: Winds less than 25 kt.

Sunday: Low risk for Small Craft Advisory winds with gusts up
to 30 kt. Seas locally approaching 5 ft.

Sunday Night: Low risk for Small Craft Advisory winds with
gusts up to 30 kt. Areas of seas approaching 5 ft.

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

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

&&

$$

SYNOPSIS...BW
NEAR TERM...BW
SHORT TERM...BW
LONG TERM...BW
AVIATION...BW
MARINE...BW