117
FXUS61 KBOX 301453
AFDBOX

Area Forecast Discussion
National Weather Service Boston/Norton MA
1053 AM EDT Mon Jun 30 2025

.SYNOPSIS...
Sunshine with warm temperatures, but high pressure exits east of the
region late Monday and clouds increase late in the day. Potential of
strong to severe storms Tuesday, a cold front clears the coast by
early Wednesday. Drying out and more seasonable temperatures heading
toward the 4th of July. Rain chances late week look low, but will
watch a shortwave move across the region Thursday/Friday timeframe
which may bring isolated activity.

&&

.NEAR TERM /THROUGH TONIGHT/...
Key Messages:

* No real weather concerns for today, sunshine, and seasonably warm
  conditions and somewhat sticky to muggy.

Coastal fog/stratus is having a challenging time moving on shore as
of writing this, 4am. 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 1.5 hours
away from sunrise. If were to get any expansion do think it would be
for the immediate 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.

Warm and somewhat sticky to muggy today, depending on your tolerance
for heat and humidity. Dew points vary across southern New England,
higher values around 65F to 68F mainly in the lower terrain, while
the higher elevations of Worcester County and the Berkshires see
slightly drier dew points of 58F to 62F. 925mb temps top out around
+22C to +24C, supporting surface highs in the upper 80s to lower
90s. With localized high pressure over the region and a weak
pressure gradient, winds start off light. 00z high-res guidance
shows a trend toward light southerly winds developing late morning
into the afternoon across the south coast, and southeast winds near
the eastern MA coast. This should keep coastal communities a bit
cooler, generally in the upper 70s to lower 80s.

Overall, a mainly sunny day, though expect high cirrus clouds to
stream in from southwest to northeast during the afternoon, giving
the sky a milky look. These clouds are out ahead of a quasi-
stationary boundary to the south that will lift north as a warm
front overnight, which could bring scattered showers and
thunderstorms early Tuesday morning, but more on that in the short
term section. 1020mb high pressure gradually becomes absorbed into
the broader Bermuda high to our south. With clouds holding on to the
day time heating, overnight lows should fall back into the mid-60s
to around 70F.

&&

.SHORT TERM /TUESDAY/...
Key Messages:

* An active weather day with periods of rain and thunderstorms.

* Warm and humid conditions, feel like temperatures 90F-95F

Think there will be three instances for activity on Tuesday, with
the warm front in the morning, a prefrontal trough midafternoon, and
a cold front late afternoon into the early evening. On top of this
active weather it will be very warm with high dew points. Let`s
break down these details below.

Showers and Thunderstorms:

Boundary to the south advances north as a warm front early Tuesday
morning and is a triggering source. SREF probs of MUCAPE of greater
than 500 J/kg and 0-6 km shear of at least 30 knots is in the range
of 20-40%, so, in addition to showers during the predawn and early
morning hours, cannot rule out isolated thunderstorms, and heavy
downpours with PWATs increasing to 2.25". As the warm front pushes
north, a forecast challenge is whether or not we clear out enough to
destabilize the atmosphere for additional rounds of convection. The
high-res models are able to capture the tail end of Tuesday and
there are inconsistencies on scattering out the clouds. While the
NAM3km is optimistic, the HRRR and HREF are a bit pessimistic. Think
if we stay socked in the clouds will limit our potential for severe
weather come the afternoon.

During the afternoon there is uncertainty with exact timing given
there is still a good amount of spread amongst the 00z CAMs per the
HREF. That said, vast majority show an active afternoon with the one
exception of the NAM Nest. In addition, these convection-allowing
models appear to develop a prefrontal trough, this could lead to a
few discrete cell development. Now, with the cold front the timing
on this has trended a little later, closer to sunset, based on the
00z guidance. And there has been little change in the severe weather
probabilities per the SREF, as noted by the previous forecaster,
SREF probabilities for MUCAPE of 1000 J/kg and 0-6 km shear of 30
kts are around 20-40% and probabilities for 2000 J/kg of Cape and 40
knots of shear are below 10%. Still, feel this is a good enough
signal for scattered thunderstorms with isolated severe storms
possible with aligns with SPC day two outlook which has maintained
our Marginal Risk.

Primary hazard at this time appears to be damaging straight-lined
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" and warm cloud depths around 12 to 14 kft, this
matches up with with the Marginal ERO from WPC. 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.

Temperatures:

As advertised, it`s another hot and pretty humid day. Mixing of the
boundary layer is limited to 950mb to 900mb, and temperatures aloft
are similar to Monday +22C to +24C, while today it is good enough to
give upper 80 and lower 90s, will have more cloud cover on Tuesday.
Think we knock off a few degrees for most places, but not by much,
high reach the mid to upper 80s, while at the south coast a bit
cooler with the on shore winds, there upper 70s and lower 80s.

Dew points increase to the low 70s, which is very noticeable, and
will make it feel warmer. Have heat index values between 90F and
95F. As noted yesterday, no need for heat advisories at this time.

&&

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

* Seasonable temperatures and lower humidity.

* Chance for showers or thunderstorms Thursday into Friday with the
  passage of shortwave.

In general, the rest of the week is shaping up well as we approach
the 4th of July! The set up going forward features troughing in the
east and northwest flow. This dries out the atmosphere as PWATs fall
below an inch and dew points fall into the 60s and upper 50s. As of
now there is no significant rain makers on the way, will watch for
Thursday into Friday as a shortwaves moves in from the northwest
this could lead to pop up showers or storms, but too early to get
into exact details. That said, PWATs remain low, so these storms
would not have much moisture to work with.

Additionally, temperatures are more seasonable weather behind the
cold front with high temperatures in the mid 80s for Wednesday and
Thursday, then the lower 80s and upper 70s Friday and Saturday. As
for nighttime lows, those hold steady in the 60s.

&&

.AVIATION /15Z MONDAY THROUGH FRIDAY/...
Forecaster Confidence Levels...

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

15z TAF Update:

Today: High confidence.

VFR. Southeast wind 8 to 12 knots.

Tonight...Moderate confidence.

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

Tuesday...Moderate confidence.

MVFR/IFR, periods of SHRA and isolated/scattered TSRA during
the afternoon, gusty SW winds 10 to 15 knots.

KBOS Terminal...Moderate confidence in TAF.

VFR with ESE winds, becoming SE then S heading into tonight.
Slight chance for SHRA going into Tuesday morning.

KBDL Terminal...High confidence in TAF.

Outlook /Tuesday Night through Friday/...

Tuesday Night: Mainly VFR, with local IFR possible. Breezy.
Chance SHRA, isolated TSRA.

Wednesday through Wednesday Night: VFR.

Thursday through Thursday Night: VFR. Slight chance SHRA,
isolated TSRA.

Independence Day: VFR.

&&

.MARINE...
Forecaster Confidence Levels...

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

Today...High confidence.

Dry. Any morning fog erodes. SW wind 10 to 15 knots with gust under
20 knots. Seas 2 to 3 feet.

Tonight and Tuesday...Moderate confidence.

Showers and thunderstorms developing overnight and through the day
on Tuesday. Southwest wind will gust 25 to 30 knots, seas building
on the outer waters to 4 to 6 ft. Have issued a Small Craft Advisory
from Tuesday late morning through Wednesday morning.

Outlook /Tuesday Night through Friday/...

Tuesday Night: Low risk for Small Craft Advisory winds with
gusts up to 25 kt. Seas up to 5 ft. Chance of rain showers,
isolated thunderstorms. Local visibility 1 to 3 nm.

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

Wednesday Night: Winds less than 25 kt. Areas of seas
approaching 5 ft.

Thursday: Winds less than 25 kt.

Thursday Night: Winds less than 25 kt. Slight chance of rain
showers, isolated thunderstorms.

Independence Day: Winds less than 25 kt.

&&

.BOX WATCHES/WARNINGS/ADVISORIES...
CT...None.
MA...None.
RI...None.
MARINE...Small Craft Advisory from 11 AM Tuesday to 6 AM EDT Wednesday
     for ANZ250-254>256.

&&

$$

SYNOPSIS...Dooley
NEAR TERM...Dooley
SHORT TERM...Dooley
LONG TERM...Dooley
AVIATION...Loconto/Dooley/Hrencecin
MARINE...Loconto/Dooley