509
FXUS61 KBOX 141916
AFDBOX

Area Forecast Discussion
National Weather Service Boston/Norton MA
316 PM EDT Wed Aug 14 2024

.SYNOPSIS...

Mostly dry and pleasant weather continues this afternoon e. Another
round of scattered showers thunderstorms is expected Thursday
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 /UNTIL 6 AM THURSDAY MORNING/...

Clear skies this afternoon with some diurnal cumulus. The exception
at the moment is for far western MA and CT where terrain is helping
to kick off some scattered showers and thunderstorms. Even though
low level lapse rates are favorable, poor mid level lapse rates and
dry mid/upper levels are keeping these storms low topped and sub
severe. Garden variety t-storms will continue over the interior
until loss of daytime heating with sunset. Tonight we`ll see some
radiational cooling but incoming clouds after midnight associated
with a subtle shortwave aloft will help to stem the cooling;
expecting lows in the 60s.

&&

.SHORT TERM /6 AM THURSDAY MORNING THROUGH THURSDAY NIGHT/...

The main weather story for Thursday is the return of more widespread
thunderstorms in the afternoon and evening as the upper trough
lingers overhead with a shortwave rotating through. Skies will be
mostly clear so plenty of sun for surface heating (highs in the low
to mid 80) and with dewpoints in the mid to upper 60s this will lead
to MUCAPE values over 1000 J/kg; plenty of instability and moisture
for some thunderstorms. Fortunately shear is quite weak (20 kts or
less) and mid level lapse rates aren`t impressive so we`re not
expecting anything severe out of these storms. That said, with PWATs
over 1 inch localized heavy downpours are possible along with some
gusty winds. Storms dissipate with sunset but onshore flow may bring
low clouds into eastern MA, RI, and even CT.

&&

.LONG TERM /FRIDAY THROUGH WEDNESDAY/...

Key points:

* Drier pattern coming to an end after Friday night with surface
  high pressure moving out of SNE

* Upper level trough moving in over the weekend into early next week
  aiding in return of unsettled weather into mid-week

* Surface high pressure looking to return going into Wednesday

Details:

The drier weather we`ve been seeing for most of this week looks to
come to a close going into Friday night as the surface high pressure
begins to make its exit. In its place, an upper level trough and its
associated cold front looks to push through SNE over the weekend,
bringing with it more SW flow aloft, higher dew points, and
generally unsettled weather. PWATs during this period do not look to
be higher than seasonably average (staying within about the 1.45-
1.68" range at their highest), and nothing in the guidance overall
is indicating any high chances for heavy downpours. Highs for most
of this period look to be in the 80s for most of our area, with
Sunday being slightly cooler than the other days following the
passage of the aforementioned cold front.

This moisture looks to start moving out of SNE around Tuesday night
into Wednesday morning as a surface front passes through. Most of
the deterministic guidance suggests the return of the surface high
pressure by mid-week, with the ensembles being a bit more neutral
when looking at MSLP anomalies. Generally, there is decent support
from the guidance for more comfortable dew points and less rain
coming in mid-week.

As of right now, there is high confidence in Hurricane Ernesto
staying far offshore for New England, but there could be some slight
risks for rip currents and higher surf over the weekend along the
southern coastlines. Will continue to monitor for the possibility
for issuing headlines for the outer waters.

&&

.AVIATION /19Z WEDNESDAY THROUGH MONDAY/...
Forecast Confidence Levels:

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

18Z updates...

This afternoon...High Confidence.

VFR. Light north winds with seabreezes along the immediate
coasts.

Tonight and Thursday...High Confidence.

VFR. Winds light and variable. Seabreezes developing by
Thursday afternoon along both coasts. Risk for afternoon
showers and thunderstorms with brief MVFR conditions.

Thursday night...High Confidence.

VFR. Winds light and variable.

KBOS TAF...High Confidence

KBDL TAF...High Confidence.

Outlook /Friday through Monday/...

Friday through Friday Night: VFR.

Saturday: VFR. Breezy. Slight chance SHRA.

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

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

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

&&

.MARINE...
Forecaster Confidence Levels:

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

Through Thursday night...High Confidence.

Relatively light winds and seas through Thursday night.
Visibility should be quite good as well. Risk for a few showers
around Cape Ann this afternoon and evening, with a greater risk
for nearshores showers and thunderstorms Thursday afternoon.

Outlook /Friday through Monday/...

Friday: Winds less than 25 kt.

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

Saturday: Winds less than 25 kt. Seas up to 5 ft.

Saturday Night: Winds less than 25 kt. Local rough seas. Slight
chance of rain showers.

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

Monday: Winds less than 25 kt. Seas up to 5 ft. Slight chance
of rain showers, isolated thunderstorms.

&&

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

&&

$$

SYNOPSIS...BW/Hrencecin/KS
NEAR TERM...BW
SHORT TERM...BW
LONG TERM...Hrencecin/KS
AVIATION...BW/Hrencecin/KS
MARINE...BW/Hrencecin/KS