-- Discussion containing changed information from previous version are highlighted. --
314
FXUS61 KBOX 280541
AFDBOX

Area Forecast Discussion
National Weather Service Boston/Norton MA
141 AM EDT Sun Apr 28 2024

.SYNOPSIS...
Warm but unsettled conditions for Sunday with a few chances for
widely scattered showers through early Monday. Mainly dry and
warm weather is on tap for Monday, except it will be
considerably cooler along portions of the immediate coast. A
backdoor cold front will bring cooler temperatures Tuesday and
Wednesday before it warms up again by late in the week. The
greatest risk for a period of showers will be later Tuesday into
Wednesday.

&&

.NEAR TERM /UNTIL 6 AM THIS MORNING/...
Update: 10PM

Warm frontal showers mainly west of KFIT, KORH, and KIJD are
falling out of high clouds base - Many of the ASOS west have
reported light rain with not much more than `T` accumulation.

KBOX shows widespread light rain west of the CT River, but this
is deceiving. Surface observations reveal a significant T/Td
spread of 15 degrees west and 30 degrees east. Clearly the lower
levels would need to saturate before a steady light rain were to
take hold.

Any way you slice it, no impactful weather coming from these
showers. No changes overall for this update as the forecast is
on track.

See previous forecast discussion below.

7 PM Update...

* A round of scattered showers especially inland from the coast
  later this evening and esp after midnight

Approaching mid level warm front/shortwave was resulting in
showers breaking out across NY State early this evening. This
will result in enough forcing/lift for a period of scattered
showers later this evening and particularly after midnight. The
showers will gradually weaken as they move east into some upper
level ridging...so showers will be more numerous inland from
the coast. However...a few brief showers will probably survive
it onto the coastal plain after midnight.

Shower activity is expected to come to an end by daybreak, but low
to mid level clouds will develop thanks to a significant jump in
moisture in the column. Given increasing cloud cover and dewpoints,
overnight lows tonight will be much milder than the last several
days, generally in the 40s, with no risk of frost across the
area!

&&

.SHORT TERM /6 AM THIS MORNING THROUGH 6 PM MONDAY/...
Sunday will be bit of an odd day with widespread morning cloud cover
giving way to above normal temperatures by mid afternoon. Mid-level
ridge regenerates and broadens allowing mild temperatures aloft, up
to 11C, but daytime heating will be slow through ~15Z before breaks
in the low/mid level cloud deck begin to develop. Once some sunshine
is able to break through the clouds, we will see temps warm quickly
into the upper 60s to low and perhaps even mid 70s, warmest across
the CT River Valley, by early afternoon. Humidity will be quite
noticeable, as dewpoints climb into the 50s by late afternoon
thanks to prolonged SW/S flow.

Convection will generate another round of afternoon showers across
upstate NY, but with limited instability, up to 100J/kg MUCAPE just
barely scraping the northwestern edge of MA, not expecting that
thunderstorms will survive a trip over the Berkshires into our
region. With that said, convective showers will weaken into widely
scattered showers as they enter our western zones, highlighted well
by the 12Z HREF, primarily affecting western MA and CT from 20-00Z
tomorrow.

Dewpoints continue to climb after sunset into the mid and perhaps
upper 50s, which will lead to an unseasonably mild night. Increased
moisture along with light SW flow will likely result in some pockets
of fog along the south coast/Cape/Islands overnight, but flow across
the interior takes a turn for the W/NW, which will limit the inland
extent of fog formation.  Another weak wave of energy dropping south
into the region overnight may initiate a few scattered rain showers
between midnight and sunrise.

&&

.LONG TERM /MONDAY NIGHT THROUGH SATURDAY/...
Key Points...

* Warm on Mon with 70s/near 80...but much cooler immediate coast
* Cooler Tue & especially Wed with 50s & 60s...coolest coast
* Milder again by Thu & Fri with 70s away from the coast
* Greatest risk for a period showers later Tue/Wed

Details...

Monday...

Upper level ridge axis just to our west will result in a generally
dry/warm day away from the immediate coast. We will have to watch
for a backdoor cold front...but thinking for Mon the primary impacts
will be along the immediate coast. Temps immediately along the coast
will be in the 60s and probably fall into the 50s across much of
that region that afternoon with onshore flow. Meanwhile...the
surface flow is rather weak inland from the immediate coast and 850T
near +9C/10C. Good mixing should yield highs well into the 70s/near
80 with the warmest of those readings lower CT River Valley. That is
our thinking right now...but it will be cooler if backdoor front
moves faster than current indications.

Tuesday and Wednesday...

High pressure over eastern Canada will allow for the backdoor cold
front to have crossed the region and result in cooler temps Tue and
Wed. Highs will probably be held in the 50s along portions of the
coast and in the 60s further across the interior. A shortwave trough
also may bring a period of showers to the region sometime later Tue
into Wed...but specific timing remains uncertain.

Thursday/Friday/Saturday...

Upper trough pushes east of the region late in the week...allowing
for upper level ridging to build back into southern New England.
This should allow highs to reach well into the 70s to perhaps even
near 80 away from the immediate coast and any sea breezes. The upper
level ridging should result in generally dry weather Thu/Fri...but a
shortwave/cold front may bring an increasing chance for showers
sometime Sat.

&&

.AVIATION /06Z SUNDAY THROUGH THURSDAY/...
-- Changed Discussion --
Forecast Confidence Levels:

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

06z TAF Update...

Through 12z... High confidence.

VFR/MVFR, becoming widespread MVFR with isolated IFR within
areas of scattered light rain showers. Winds are south-southwest
5 to 10 knots, locally higher gusts to 20 knots near the coast.


Today... High confidence.

MVFR/IFR conditions early in the morning. Improving cigs after
16z, trending VFR some time after 18z/20z. Lower cigs may linger
later into the afternoon for terminals on Cape Cod & Islands
into the late afternoon. Winds are southwest 8 to 12 knots.

Tonight... Moderate confidence.

Generally VFR away from the Cape and Islands where patchy fog
will develop. Winds are southwest to start, transitioning to
the west-northwest across the interior by daybreak.

Monday... Moderate confidence.

VFR, mid-level clouds across western terminals 050-070k ft.
Northerly winds for most, but do expect a sea breeze for
eastern Massachusetts, east-northeast winds along the north and
south shore of Boston. Sea breeze may be strong enough to reach
KPVD with a east-northeast wind.

KBOS TAF...High confidence in TAF. Scattered showers possible
between 08Z and 12Z. MVFR develops behind diminishing showers
for the better part of the morning. VFR at times later this
afternoon, before returning to MVFR/IFR overnight.

KBDL TAF...High confidence in TAF. Scattered showers through
09z, becoming MVFR shortly after. VFR conditions later this
afternoon along with a low chance of a brief afternoon shower.
Trending back to MVFR tonight.

Outlook /Monday Night through Thursday/...

Monday: Mainly VFR, with local MVFR possible. Breezy.

Monday Night: Mainly VFR, with local MVFR possible. Slight
chance SHRA.

Tuesday: Mainly VFR, with areas MVFR possible. Slight chance
SHRA.

Tuesday Night: Mainly MVFR, with local IFR possible. Chance
SHRA.

Wednesday: Mainly MVFR, with local IFR possible. Breezy. Chance
SHRA.

Wednesday Night: Mainly MVFR, with areas VFR possible. Slight
chance SHRA.

Thursday: Mainly VFR, with local MVFR possible. Slight chance
SHRA.
-- End Changed Discussion --

&&

.MARINE...
-- Changed Discussion --
Forecaster Confidence Levels:

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

Through Sunday night... High confidence.

Generally tranquil boating conditions expected through Sunday
outside of a few rounds of widely scattered showers overnight
tonight and tomorrow evening. Onshore breeze across the eastern
waters will subside quickly this evening giving way to primarily
south/southwest winds for Sunday. Some patchy fog possible
Sunday night.

Seas mainly 3ft or less all waters.

Outlook /Monday Night through Thursday/...

Monday through Monday Night: Winds less than 25 kt.

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

Tuesday Night through Wednesday: Winds less than 25 kt. Chance
of rain showers.

Wednesday Night through Thursday: Winds less than 25 kt. Slight
chance of rain showers.
-- End Changed Discussion --

&&

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

&&

$$

SYNOPSIS...Frank/KS
NEAR TERM...Frank/Dooley/KS
SHORT TERM...KS
LONG TERM...Frank
AVIATION...Frank/Dooley
MARINE...Frank/KS