385
FXUS61 KBOX 211747
AFDBOX

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

.SYNOPSIS...
Offshore low remains stagnant through this evening and begins
to move to the southeast Sunday and continue through Monday.
While dry weather is expected Sunday through Tuesday, cloudier
conditions and onshore breezes are expected, along with a risk
for higher surf through Monday. Rain chances then increase again
for midweek as a frontal system moves in from the Great Lakes.
Near to slightly below normal temperatures are expected into
midweek.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
10 AM update...

Quasi-stationary coastal storm east of the Benchmark will
continue to bring bands of windswept rain to eastern MA today.
Rain will be heavy at times across SE MA and Cape Cod as decent
area of 850 mb frontogenesis persists across this area.
Additionally, there is some elevated instability just offshore
which may lead to an isolated t-storm across the Cape/Islands.
Visible satellite loop indicates convective clouds just east of
Cape Cod. Additional rainfall today of 0.50-1.00" is likely
across coastal SE MA, heaviest from Plymouth county to Cape Cod
where locally more than an inch is possible. Total rainfall
since Thursday night is 4-7 inches over the outer Cape, with
1-3 inches from Plymouth county to the upper Cape.

Further W, expect scattered showers from central MA to eastern
CT with dry conditions with partial sunshine across CT valley.

Temps will hold steady in the upper 50s and lower 60s across
eastern MA with highs reaching upper 60s to around 70 in CT
valley. Gusty NE winds with gusts to 35 mph across Cape Cod will
slowly diminish this afternoon. Otherwise, expect 20-30 mph
gusts along the immediate coast.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM SUNDAY/...
Tonight and Tomorrow

Area of low pressure south of Nantucket slowly retrogrades
southeast. Latest model guidance suggests it will regress far
enough that low-level jet will shift south off the south coast
bringing an end to the steady rainfall and stronger northeast
wind gusts. Nonetheless, elevated northeast winds persist
tonight from 10 to 20 mph with some gusts in the 20 to 30 mph
range near the coast. Lows bottom out in the mid too upper 50s
across eastern MA and RI. Areas to the west may see some
clearing overnight, particularly areas near the CT River Valley.
This would allow for slightly cooler temperatures in the lows
50s overnight.

Sunday will feature very slow improvements to the cloudy/dreary
pattern we`ve been stuck in since mid-week. Not expecting any
precipitation, but overcast skies will be likely across eastern
MA and RI for most of the day. Should see some breaks of sun
west of Worcester where high temperatures will be pleasant in
the upper 60s to low 70s. Can`t rule out some late sunshine for
areas east of Worcester as skies gradually clear with the area
of low-pressure off the south coast continuing to move out to
sea.

&&

.LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/...
Highlights:

* While dry, still a cloudier-than-not period with continued NE
  breezes through Tue. High surf and/or elevated risk for rip
  currents as well through at least early next week, and minor
  coastal flooding on east-facing coasts again possible into
  Sun.

* Frontal system around Wed or Thu offers the next chance for
  rainfall, although the timing remains uncertain.

* Temperatures near to slightly below normal.

Details:

The stagnant low pressure finally gets kicked out to sea as a
high pressure builds over southern New England from eastern
Canada. This high pressure will dominate our weather with drier
and cooler conditions into at least early Wednesday. Some
question after then about how quickly this high pressure will
move off to the east and permit a low pressure to move into the
Great Lakes. Latest guidance suite may be a little too fast
returning a risk for showers Wednesday given the synoptic
pattern. Given the uncertainty in the details, stayed closer to
the NationalBlend solution. More confident in unsettled weather
redeveloping late next week as a low pressure passes by.

With the continued northeasterly flow and elevated seas, there
will continue to be a risk for rip currents and high surf with
a need for rip current and/or surf headlines for the eastern
coast. While astronomical tides trend lower each day, we could
still have pockets of minor coastal flooding and/or washover
onto vulnerable shoreline roads Monday, but the risk is
considerably lower than this weekend.

Northeast winds become east Tuesday, then persist into late next
week. This will keep temperatures near to slightly below normal.

&&

.AVIATION /18Z SATURDAY THROUGH WEDNESDAY/...
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 Wednesday/...

Monday: VFR. Breezy.

Monday Night: Mainly VFR, with local MVFR possible.

Tuesday: Mainly VFR, with areas MVFR possible.

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

Wednesday: Mainly VFR, with areas MVFR possible. Chance SHRA.

&&

.MARINE...
Forecaster Confidence Levels:

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

Today through Sunday

Gale force wind gusts gradually die down today over the south
coastal waters, but seas remain elevated with significant wave
heights continuing to range from 6 to 10 feet over the marine zones.
While gale force gusts should diminish by this afternoon, still
expect persistent northeast winds with gusts up to 30 knots. This
pattern will continue through at least Sunday.SCY headlines will be
needed through this time frame. A High Surf Advisory remains in
effect for the southern New England coastline.

Outlook /Sunday Night through Wednesday/...

Sunday Night: Low risk for Small Craft Advisory winds with
gusts up to 30 kt. Rough seas up to 11 ft.

Monday: Winds less than 25 kt. Rough seas up to 10 ft.

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

Tuesday through Tuesday Night: Winds less than 25 kt. Areas of
rough seas.

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

&&

.TIDES/COASTAL FLOODING...
Coastal Flood Advisory remains in effect for this afternoons high
tide. Storm surge associated with the area of low-pressure south of
Nantucket likely peaked yesterday around 1.6-1.7 feet. There were
several reports of minor coastal flooding along the east coast. With
total water levels slightly lower today, we don`t anticipate impacts
any worse than what was observed yesterday, but we do expect another
round of minor coastal flooding with todays high tide. With the area
of low-pressure slowly retrograding southeast, the elevated water
levels will persist into tomorrow afternoons` high tide when another
Coastal Flood Advisory will be in effect.

In addition...because this is a long duration event there is
also concern for beach erosion. This is especially true for
areas that were hard hit by the storms of last winter.

Lastly...we have gone with High Surf Advisories for all ocean
exposed beaches along both coasts given the rough seas offshore.

&&

.BOX WATCHES/WARNINGS/ADVISORIES...
CT...None.
MA...High Surf Advisory until 7 PM EDT this evening for MAZ007-019-
     020-022>024.
     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.
RI...High Surf Advisory until 7 PM EDT this evening for RIZ006>008.
MARINE...Small Craft Advisory until 4 PM EDT this afternoon for ANZ230-
     236.
     Small Craft Advisory until 8 PM EDT Sunday for ANZ231>235-237-
     250-251-254>256.

&&

$$

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