034
FXUS61 KBOX 151509
AFDBOX

Area Forecast Discussion
National Weather Service Boston/Norton MA
1109 AM EDT Thu Aug 15 2024

.SYNOPSIS...
Scattered showers thunderstorms are expected this afternoon and
evening. Dry weather returns Friday and may linger into
Saturday, especially across RI and eastern MA. Then a frontal
system may bring scattered showers and thunderstorms Sunday
through Tuesday. Probably not a washout, with periods of dry
weather too during this time. Meanwhile, Ernesto will track well
southeast of New England, but it will bring rough surf and
strong rip currents to south-facing ocean beaches of RI and MA
this weekend.

&&

.NEAR TERM /THROUGH TONIGHT/...
1105 am update...

Forecast tracking along pretty well to observations, so no
changes have been made. Think the primary "show" this afternoon
will be the cluster of convection that is tracking southward in
Maine and NH at this time. Hi-res models are struggling with the
convection right now, and the belief is that the models are a
little slow with when it depicts convection across southern New
England. Tracking the convection to the north, which should
maintain itself as it`s associated with the shortwave, it
should reach northeast MA about 17z (1pm). As instability
develops this afternoon, we should see additional convection as
well. Environment will support a few strong t-storms, with the
primary threat being local downbursts, given semi-decent mid
level lapse rates around 6.5C and DCAPE progged to be in the
800-1000 J/kg range.


Previous discussion....

Still expecting scattered showers and
thunderstorms today as a cold pool aloft nudges closer to
southern New England. Decent instability in most model outputs
with most unstable CAPE values between 1,000-1,500 J/kg. Shear
values of 20-30 kt and fairly straight hodographs suggest more
of wind threat. Wet-bulb freezing level is projected to be less
than 10 kft, which also suggests that some hail is a
possibility. The lack of a major focus should lead to rapid
weakening near and after sunset.

Despite more clouds today, high temperatures should be near
normal. Seabreezes develop once again, keeping the coasts cooler
for a time this afternoon.

&&

.SHORT TERM /FRIDAY/...
High pressure moves in tonight into Friday. Once lingering
evening convection has ended, expecting dry weather through
Friday. Light winds will lead to another round of seabreezes
Friday. Near normal temperatures should persist.

&&

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

* Seasonable temperatures persist this weekend but with
  increased humidity

* A slow-moving frontal boundary approaching from the west will
  result in increased rain chances Sunday and Monday

* Cooler/drier conditions settle in behind a cold front by the
  middle of next week


Saturday

Latest suite of model guidance has slowed the eastward
progression of an upper-level trough and associated surface cold
front this weekend. This has resulted in a drier outlook for
Saturday with low rain chances across southern New England. Deep
southerly flow will continue to support seasonable temperatures
in the low 80s, but with increased humidity as dewpoints rise
into the mid to upper 60s. Ridging aloft should support a good
amount of sunshine, but expect at least a mix of sun and clouds
with the increased low-level moisture.

Sunday and Monday

Rain chances increase Sunday into Monday as a cold front
approaches the region from the west. Guidance has been trending
toward a later arrival of the front, thus at least some of
Sunday could feature dry weather for portions of southern New
England, mainly eastern MA and RI. Cloud cover will be driven by
how far east the front progresses by Sunday afternoon, but
generally expect more cloudiness further west with better
chances for sunshine to the east. By Monday confidence increases
in rain chances across the region as the aforementioned cold
front should push through The Northeast Monday afternoon into
Monday night. With PWATs up to 1.5", this should support a good
soaking of rainfall with scattered to numerous showers and
thunderstorms. Details in timing and precipitation amounts are
vague at this time range, so stay tuned for further details.

Next Week

As the aforementioned cold front pushes through the region
during the Tuesday/Wednesday time frame, we should trend toward
drier/cooler weather as northwest winds usher a more early fall
like air mass over The Northeast with highs/lows in the
mid 70s/mid 50s respectively.

&&

.AVIATION /15Z THURSDAY THROUGH MONDAY/...
Forecast Confidence Levels:

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

Today...Moderate Confidence.

Mainly VFR. Winds light and variable. Seabreezes developing by
this afternoon along both coasts. Risk for afternoon showers
and thunderstorms with brief MVFR conditions. Smoke aloft may
lead to visibility reductions and pseudo-overcast conditions
around 4000 ft.

Tonight and Friday...High Confidence.

VFR. Winds light and variable. Seabreezes by late morning
Friday.

KBOS TAF...Moderate Confidence.

VFR conditions prevail today, but with a risk for afternoon
showers and thunderstorms. General window is 16-00Z, but more
likely in the 17-21Z time frame.

KBDL TAF...Moderate Confidence.

VFR conditions prevail today, but with a risk for afternoon
showers and thunderstorms. General window is 16-00Z, but more
likely in the 17-21Z time frame.

Outlook /Friday Night through Monday/...

Friday Night through Saturday: VFR.

Saturday Night: VFR. Chance SHRA.

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

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

Monday: Mainly MVFR, with areas VFR possible. SHRA likely,
isolated TSRA.

&&

.MARINE...
Forecaster Confidence Levels:

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

Through Friday...High Confidence.

Relatively light winds and seas through Friday. Visibility
should be quite good as well. Risk for scattered nearshore
showers and thunderstorms this afternoon to just past sunset.

Outlook /Friday Night through Monday/...

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

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

Saturday Night: Winds less than 25 kt. Local rough seas.

Sunday through Sunday Night: Winds less than 25 kt. Areas of
rough seas. Slight chance of rain showers.

Monday: Winds less than 25 kt. Areas of rough seas. Chance of
rain showers, isolated thunderstorms.

&&

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

&&

$$

SYNOPSIS...Belk/RM
NEAR TERM...Belk/Nash
SHORT TERM...Belk
LONG TERM...RM
AVIATION...Belk/RM
MARINE...Belk/RM