599
FXUS61 KBOX 291915
AFDBOX

Area Forecast Discussion
National Weather Service Boston/Norton MA
315 PM EDT Sun Jun 29 2025

.SYNOPSIS...
Warming up Monday through much of next week, will have to watch
for a cold front on Tuesday that could bring strong to severe
thunderstorms.

&&

.NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
Key Messages:

* Stratus and fog expected to return to eastern MA and parts of
  RI

Relatively quiet weather through tonight. Light onshore winds
will help regenerate marine stratus and areas of fog across the
eastern third of southern New England. Farther inland, like in
the CT River Valley, looking at more of a radiation fog
scenario.

Anticipating near to slightly above normal temperatures.

&&

.SHORT TERM /6 AM MONDAY MORNING THROUGH MONDAY NIGHT/...
Key Messages:

* Heating up Monday with some high temperatures on either side
  of 90F.

Monday is quiet, high pressure moves across the region and will
lead to another warm day, especially away from the immediate
coastline. Any lingering stratus should dissipate during the
morning, leaving plenty of sunshine for the afternoon.
Increasing humidity through Monday night. No need for a Heat
Advisory at this time.

Slightly above normal temperatures continue.

&&

.LONG TERM /TUESDAY THROUGH SUNDAY/...
Key Messages:

* Hot and humid conditions continue on Tuesday.

* Isolated strong to severe thunderstorms possible Tuesday.

* More seasonable weather for Wednesday-Friday.

Hot and humid conditions continue on Tuesday as an upper-level
ridge builds in with southwesterly mid-level flow. 850mb
temperatures will warm to +18 to +20C, which will translate to
surface temperatures in the 90s with full sunshine. With surface
flow turning southerly, dewpoints are expected to rise into the
low to mid-70s for Tuesday. Heat advisories appear unlikely at
this time, as heat index values are not expected to rise above
100F on Tuesday and are unlikely to reach 95F for two
consecutive days.

A 500mb shortwave and surface cold front moves through late
Tuesday. With good height falls and forcing combined with decent
instability and shear, the ingredients for organized severe
thunderstorms look to be coming together for late Tuesday
afternoon to evening. SREF probabilities for MUCAPE of 1000 J/kg
and 0-6 km shear of 30 kts are around 20-40%. However, the
probabilities for 2000 J/kg of Cape and 40 knots of shear are
below 10%. This is a good signal for scattered thunderstorms
with isolated severe possible. There is still some uncertainty
regarding the timing of the cold fronts arrival before peak
diurnal heating ends. There is not much high- resolution
guidance to lean on this far out, but the Nam-3k suggests the
cold front will arrive around 4 PM, while the RRFS has it
arriving around 8 PM. The primary hazard at this time appears to
be damaging wind gusts with low-level lapse rates of 10 C/km
and strong forcing from the cold front. The secondary threat
will be heavy rain, with PWATS around 2.25 inches and warm cloud
depths around 12 kft. Thinking storm mode will be a linear line
of storms, but cant rule out isolated hail or tornado threat
should a discrete supercell form out ahead of the line.

More seasonable weather behind the cold front for the remainder
of the week, with high temperatures in the 80s and dewpoints in
the upper 50s to low 60s. A stronger shortwave and cold pool
will drop south from Canada sometime on Thursday into Friday,
which could bring another round of showers and thunderstorms,
but they are not expected to be severe at this point.

&&

.AVIATION /19Z SUNDAY THROUGH FRIDAY/...
Forecaster Confidence Levels...

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

Through 00Z...Moderate confidence.

Lingering IFR east of BOS will make a westward push into
eastern MA this evening. Just not very confident on the timing.
Tough to determine cloud bases over the ocean as well. Thinking
at least IFR, but could become LIFR quickly at BOX, as well as
the Cape terminals.

Tonight...High confidence.

VFR for some, with IFR expected for most of eastern MA and
perhaps RI. Some IFR in valley fog and stratus farther inland.
Light winds.

Monday...High confidence.

VFR and dry. Southwest wind 8 to 12 knots.

Monday Night...Moderate confidence.

VFR for most. IFR/MVFR possible towards the south coast of MA
and RI.

KBOS Terminal...High confidence in TAF trends, low in timing.

KBDL Terminal...High confidence in TAF.

Outlook /Tuesday through Friday/...

Tuesday: Mainly VFR, with areas MVFR possible. Breezy. Chance
SHRA, chance TSRA.

Tuesday Night: VFR. Breezy. Chance SHRA, slight chance TSRA.

Wednesday: VFR. Breezy.

Wednesday Night: VFR.

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

Thursday Night through Independence Day: VFR.

&&

.MARINE...
Forecaster Confidence Levels...

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

High confidence.

Areas of marine fog redeveloping tonight. Visibility 1 NM or
less in spots. Fog should dissipate Monday morning. Relatively
light winds and seas continue through Monday night.

Outlook /Tuesday through Friday/...

Tuesday: Moderate risk for Small Craft Advisory winds with
gusts up to 25 kt. Areas of seas approaching 5 ft. Slight
chance of rain showers, slight chance of thunderstorms.

Tuesday Night: Low risk for Small Craft Advisory winds with
gusts up to 25 kt. Areas of seas approaching 5 ft. Chance of
rain showers, slight chance of thunderstorms.

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

Wednesday Night: Winds less than 25 kt. Seas locally
approaching 5 ft.

Thursday through Thursday Night: Winds less than 25 kt.

Independence Day: Winds less than 25 kt. Seas locally
approaching 5 ft.

&&

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

&&

$$

SYNOPSIS...Belk/KP
NEAR TERM...Belk
SHORT TERM...Belk
LONG TERM...KP
AVIATION...Belk/KP
MARINE...Belk/KP