920
FXUS61 KBOX 211943
AFDBOX

Area Forecast Discussion
National Weather Service Boston/Norton MA
343 PM EDT Sat Sep 21 2024

.SYNOPSIS...
Offshore low remains stagnant through this evening and begins
to move further offshore Sunday and continue through Monday.
While mainly dry weather is expected Sunday through Tuesday,
cloudier conditions and onshore breezes are expected. Rain
chances then increase again for midweek as a frontal system
moves in from the Great Lakes. Temperatures will be below
normal.

&&

.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
Widespread rain continues to back in from the ocean, impacting
eastern MA and RI. Well defined trowal across eastern New Eng on the
NW periphery of the upper low with excellent easterly inflow tied to
a 40 kt low level jet contributing to occasional heavy rain across
SE MA and Cape Cod where PWATs 1.5"+. So a situation where we have
fall dynamics acting on late summer moisture to bring heavy
rainfall. Rainfall amounts of 1-2 inches since 12z across portions
of Cape Cod and Plymouth county.

The ocean storm east of the benchmark will slowly push further
offshore tonight as it drifts SE. Deep moisture plume and low level
jet will slowly move offshore so rain will gradually taper to
scattered showers from N to S through the night across RI and
eastern MA. It will be a wet evening but expect some improvement
overnight, although the steady rain will likely persist through the
night across Cape/Islands. Dry conditions expected across western MA
and much of northern CT with varying amounts of clouds. Some late
patchy fog is possible

Lows will be in the 50s. Gusty NE winds near the coast will slowly
diminish but remain gusty with 20-30 mph gusts Cape/Islands.

&&

.SHORT TERM /6 AM SUNDAY MORNING THROUGH SUNDAY NIGHT/...
Sunday...

Continued improvement expected as offshore low pres continues to
move offshore. Good drying in the column moves in from the north
across the interior in the afternoon so clouds should give way to
partly sunny skies here. However, closer to the coast, deeper
moisture will be slower to depart so clouds will dominate across RI
and eastern MA and can`t rule out a few lingering showers across SE
MA and Cape Cod, especially in the morning. It will remain breezy
near the coast as strong pressure gradient in place on NW periphery
of the ocean storm. NE gusts to 20-30 mph expected along the coast,
strongest gusts over the Cape/Islands. Another cool day with below
normal temps, with highs mid-upper 60s. with some lower 70s in the
CT valley.

Sunday night...

Surface and mid level ridging builds into the region Sun night with
continued drying. Dry conditions expected with partly cloudy skies,
but patchy fog and stratus may develop overnight. Lows will drop
into the 40s, except low-mid 50s near the coast where a steady NE
wind will continue. NE winds will diminish but still expect gusts to
15-25 mph along the SE New Eng coast.

&&

.LONG TERM /MONDAY THROUGH SATURDAY/...
Highlights...

* Onshore surface flow much of the week will yield generally dreary
  conditions

* Frontal system sometime mid to late week brings another chance for
  rain

Low pressure that brought much needed rainfall to eastern southern
New England over the weekend will continue to shift to our
southeast, out into the more open Atlantic, early next week. While
the low wont have a dominant effect on our weather for next work
week, it will meander around the Bermuda area for a good portion of
the week. For Tuesday and Wednesday, mid level ridging will build
across the mid-Atlantic, leaving us in the northern fringes of the
ridge, but onshore surface flow will counteract any expected warming
effects from the ridge. Given onshore flow, expecting considerable
cloudiness much of the week.

Mid level cutoff low begins to develop mid week and its associated
trough will cut south into southern Quebec and northern New England
on Wednesday and Thursday. Front associated with this cutoff will
bring our next best chance for rain. Trough remains draped over
southern New England through at least Saturday, which will support
unsettled, showery conditions to round out the work week and start
the weekend.

Temperatures look to respect the page turn from astronomical Summer
to astronomical Fall, which occurs on Sunday the 21st. Highs will be
below normal to start the week ranging from the upper 50s in the
high terrain of western and central MA to the mid 60s to low 70s
elsewhere the first half of the week. Gradual warming trend is
possible late week, with widespread highs in the 70s expected Friday
and Saturday.

As mentioned by the previous forecaster, persistent onshore flow
will lead to a continued risk for rip currents and high surf through
at least Tuesday. With the Harvest Moon waning, coastal flooding
concerns will decrease each day, though it is possible some
splashover occurs during the Monday daylight high tide.

&&

.AVIATION /20Z SATURDAY THROUGH THURSDAY/...
Forecast Confidence Levels:

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

Through 00z...

MVFR-IFR conditions in rain eastern MA/RI. VFR CT valley. N-NE
wind gusts 20-30 kt with higher gusts Cape/Islands.

Tonight...Moderate Confidence.

MVFR-IFR conditions eastern MA and RI improving to VFR in NE MA,
but MVFR persisting SE MA and RI. VFR CT valley but patchy late
night fog possible. Rain gradually tapers off to scattered
showers overnight in eastern MA/RI, but rain persisting
Cape/Islands. Diminishing N-NE wind, but gusts 25-30 kt
Cape/Islands.

Sunday...Moderate Confidence.

Mainly MVFR cigs central-E MA and RI and VFR CT valley.
Scattered showers lingering Cape/Islands and SE MA in the
morning. NE wind gusts to 25 kt Cape/Islands and up to 20 kt
near the coast.

Sunday night...Moderate Confidence.

Mainly VFR, but areas of MVFR cigs may linger RI and SE MA.
Diminishing NE wind.

BOS TAF...Moderate confidence.

MVFR conditions with occasional IFR possible should improve
tonight, but cigs may vary between MVFR-VFR into Sunday.

BDL TAF... High Confidence. VFR.

Outlook /Monday through Thursday/...

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

Monday Night: VFR.

Tuesday: Mainly VFR, with areas MVFR possible.

Tuesday Night: Mainly VFR, with local IFR possible.

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

Wednesday Night through Thursday: Mainly VFR, with areas IFR
possible. Chance SHRA.

&&

.MARINE...
Forecaster Confidence Levels:

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

Tonight through Sunday Night...

NE gusts to 25-30 kt will continue into Sun, especially across
southern waters and waters E of Cape Cod with 8-10 ft seas over the
outer waters. Winds will slowly subside late Sunday night but rough
seas will continue.

Outlook /Monday through Thursday/...

Monday: Winds less than 25 kt. Rough seas up to 11 ft.

Monday Night: Winds less than 25 kt. Rough seas up to 9 ft.

Tuesday through Tuesday Night: Winds less than 25 kt. Rough
seas up to 8 ft.

Wednesday: Winds less than 25 kt. Areas of rough seas.

Wednesday Night: Winds less than 25 kt. Seas up to 5 ft. Chance
of rain showers.

Thursday: Winds less than 25 kt. Areas of rough seas. Chance of
rain showers.

&&

.TIDES/COASTAL FLOODING...
Coastal Flood Advisory remains in effect for Sunday afternoon high
tide. While astronomical tides remain elevated, the tides are slowly
coming down from the peak Fri and Sat. With a 1-1.5 ft surge
anticipated, we expect areas of very minor inundation or splashover
during the Sun afternoon high tide for vulnerable shoreline roads
across east coastal MA.

The High Surf Advisory was extended through Sunday due to high seas
and rough surf which will continue.

&&

.BOX WATCHES/WARNINGS/ADVISORIES...
CT...None.
MA...Coastal Flood Advisory until 5 PM EDT this afternoon for
     MAZ007-015-016-019-022>024.
     Coastal Flood Advisory from noon to 6 PM EDT Sunday for MAZ007-
     015-016-019-022>024.
     High Surf Advisory until 8 PM EDT Sunday for MAZ007-019-020-
     022>024.
RI...High Surf Advisory until 8 PM EDT Sunday for RIZ006>008.
MARINE...Small Craft Advisory until 10 PM EDT this evening for ANZ230-
     236.
     Small Craft Advisory until 8 AM EDT Monday for ANZ231-232-250-
     251-254>256.
     Small Craft Advisory until 2 AM EDT Monday for ANZ233>235-237.

&&

$$

SYNOPSIS...KJC/KS
NEAR TERM...KJC
SHORT TERM...KJC
LONG TERM...KS
AVIATION...KJC/KS
MARINE...KJC/KS
TIDES/COASTAL FLOODING...KJC