-- Discussion containing changed information from previous version are highlighted. --
044
FXUS61 KBOX 300545
AFDBOX

Area Forecast Discussion
National Weather Service Boston/Norton MA
145 AM EDT Mon Jun 30 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 THIS MORNING/...

-- Changed Discussion --
Coastal fog/stratus is having a challanging time moving on shore
as of writing this, 145am. And at this hour the only location
that is experiencing localized dense fog is Nantucket, ASOS
reporting 1/4 to 1/2 mile of visibility. Have lower confidence
in the fog expanding to the levels seen on Sunday morning as we
are less than 3.5 hours away from sunrise. If were to get any
expansion do think it would be for the immedate coastal areas
and those inland protected areas. Good news, there is little to
no cloud cover so any morning fog will quickly erode with
daytime heating.
-- End Changed Discussion --

&&

.SHORT TERM /6 AM THIS MORNING THROUGH 6 PM TUESDAY/...
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 NIGHT 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 /06Z MONDAY THROUGH FRIDAY/...
-- Changed Discussion --
Forecaster Confidence Levels...

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


Tonight...Low confidence.

Guidance has really reversed course on tonight, once very
pessimistic brining in LIFR conditions to much of eastern MA
and RI, now leaning VFR as surface winds flip more westerly.
Still don`t have alot of confidence as the HRRR is still
hitting the low status and fog hard, but light westerly winds
favor clearer conditions. If conditions remain clear, could see
radiation for in our low lying areas

Monday...High confidence.

Any fog that forms overnight should burn of quickly with
sunrise. otherwise 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...Low confidence in TAF.

Guidance seems to be trending more VFR as winds try to turn more
westerly. However, if winds stay onshore again tonight, could
see low status and fog move back in.

KBDL Terminal...High confidence in TAF.

VFR. Light NW winds turning SW tomorrow.

Outlook /Tuesday Night 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.
-- End Changed Discussion --

&&

.MARINE...
-- Changed Discussion --
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 Night 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.
-- End Changed Discussion --

&&

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

&&

$$

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