-- Discussion containing changed information from previous version are highlighted. --
614
FXUS61 KBOX 020530
AFDBOX

Area Forecast Discussion
National Weather Service Boston/Norton MA
130 AM EDT Thu May 2 2024

.SYNOPSIS...
A weak low pressure will bring scattered showers near the coast
Thursday. High pressure north of our region will bring dry and
seasonable weather Friday and most of Saturday with onshore
winds. An approaching front should bring showers late Saturday
into Sunday. Dry and warmer weather is expected early next week.

&&

.NEAR TERM /UNTIL 6 AM THIS MORNING/...
Loss of daytime heating is leading to clearing skies this
evening. However, stratus was lurking just offshore. This
stratus is expected to return later tonight once the flow turns
first light SE then S. Will also need the boundary layer to
cool a little bit, decreasing the dew point depressions.

Mainly dry overnight, except for the risk of some passing
showers towards daybreak across the eastern half of MA.

Previous Discussion...

Mainly dry the rest of today with a low chance for an isolated
shower across the Berkshires and CT river valley this afternoon
as 100-200 J/kg of SBCAPE builds with some sunshine. Low clouds
and pockets of fog form again overnight as surface winds turn
south and bring in low level moisture. Overnight lows again stay
in the mid to upper 40s with low cloud cover and weak warm air
advection.

&&

.SHORT TERM /6 AM THIS MORNING THROUGH 6 PM FRIDAY/...
Tomorrow:

Shortwave trough and associated surface low drops south from
northern New England. An area of light showers associated with a
cold front move through tomorrow morning, however, guidance is
mixed on the extent south and intensity of these showers. The
best forcing for showers looks to mainly stay confined to
northeast MA. Later in the afternoon, the center of the low
pressure and core of shortwave energy passes over eastern MA. At
this point, 100-200 J/kg of MUCAPE will be able to build,
allowing for isolated convective showers to form across eastern
MA, with the best chance over northeast MA again. With the low
amount of instability, there is a low chance for a rumble of
thunder with any showers tomorrow afternoon. Confidence was not
high enough to include mention in the forecast database at this
point.

High temperatures have trended warmer tomorrow with SSW flow,
and increasing chances for sunny to partly sunny skies across
western MA and CT. Stuck with the NBM for temperatures tomorrow
with highs in the mid to upper 70s in the CT river valley, and
upper 60s to low 70s in RI and Eastern MA away from the coasts.

Tomorrow night:

Winds shift NE overnight as the center of the low moves south
offshore and high pressure builds in to the north. This will
bring all the low clouds and fog back onshore, eventually
pushing west over much of the region. This keeps low temps mild
once again only dropping into the upper 40s to low 50s. Rain and
shower chances quickly decrease as the low exits and upper
level ridge builds in.

&&

.LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/...
Key Points:

 * Overall quiet weather pattern ahead
 * Scattered showers late Saturday into Sunday
 * Warmup early next week

Still have the greatest confidence in dry weather persisting
through most of Saturday. Still some disagreement in when
showers could arrive late Saturday into Sunday. Both the 01/12Z
GFS and CMC suggest at least a risk for showers along the east
coast of MA late Saturday afternoon, while the larger
NationalBlend ensemble maintains dry weather for the same time
frame. Given the synoptic pattern, with a high pressure just to
the east of New England, favoring the drier NationalBlend
solution into Saturday night. This still pushes the focus for
weekend showers into Sunday.

Trickier forecast for earlier next week. Latest guidance suite
still exhibited some timing and amplitude differences with the
evolution of a mid level longwave trough near the Rockies. This
will eventually impact our weather downstream. Our proximity to
a surface front will be critical to our forecast outcome. At
present, thinking this front will be pushed far enough south
where mainly dry weather prevails Monday and Tuesday, before
returning north as a warm front some time Tuesday night into
Wednesday.

Near normal temperatures expected through Saturday, before
briefly trending below normal Sunday. Likely to see above normal
temperatures early next week.

&&

.AVIATION /05Z THURSDAY THROUGH MONDAY/...
-- Changed Discussion --
Forecast Confidence Levels:

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

06Z TAF

Through 12Z...Moderate Confidence

GOES nightime microphysics is beginning to show SCT to BKN lower
cloud bases filling in across southern New England. Still
expecting VFR ceilings to fall to IFR as we approach sunrise
and likely by 12Z. Light south winds.


Today...High Confidence in Trends

MVFR/IFR ceilings will lift/scatter out late morning/early
afternoon from west to east. Thus, VFR conditions should
prevails for most of the day. Winds increase close to 10 knots
and shift form south to southwest through about 18Z. Thereafter,
a weak low-pressure circulation will move over east/northeast MA
resulting in winds shifting to east and eventually northeast by
00Z. A few showers will be possible at BOS/BED and The
Cape/Islands terminals between 21 and 00Z.


Tonight...High confidence

IFR ceilings return overnight with steady northeast winds from
5 to 10 knots.

Tomorrow... High confidence.

MVFR/IFR ceilings lift/scatter out to VFR by mid-morning. Steady northeasterly winds becoming more
easterly after 18Z.


KBOS TAF...Moderate confidence

Not expecting LIFR ceilngs for the morning push. MVFR should be
the prevailing flight category, but can`t rule out cloud bases
getting just below 1000 feet.

KBDL TAF...Moderate confidence.

IFR ceilings likely develop between 06-12Z but will improve to
VFR by 15Z.


Outlook /Friday Night through Monday/...

Friday: Mainly VFR, with local MVFR possible.

Friday Night: VFR.

Saturday: Mainly VFR, with local MVFR possible.

Saturday Night: Mainly VFR, with local IFR possible. Slight
chance SHRA.

Sunday: MVFR/IFR conditions possible. Chance SHRA.

Sunday Night: Mainly VFR, with areas IFR possible. Chance SHRA.

Monday: 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.

Tonight: Winds shift south tonight remaining 10 knots or less
with calm seas.

Tomorrow:

Weak low pressure brings scattered showers and a low chance for
a rumble of thunder mainly across the northern waters. Winds
remain south at 10-15 knots gusting 20 knots. Light seas of 1-3
feet.

Tomorrow night: Low clouds and fog possible overnight. Winds
turn ENE again at 5-10 knots and seas remain 1-3 feet.

Outlook /Friday Night through Monday/...

Friday through Saturday: Winds less than 25 kt.

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

Sunday: Winds less than 25 kt. Chance of rain showers.

Sunday Night: Winds less than 25 kt. Seas locally approaching
5 ft. Chance of rain showers.

Monday: Winds less than 25 kt. Seas locally approaching 5 ft.
Slight chance of rain showers.
-- End Changed Discussion --

&&

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

&&

$$

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