842
FXUS61 KBOX 221119
AFDBOX

Area Forecast Discussion
National Weather Service Boston/Norton MA
719 AM EDT Sun Sep 22 2024

.SYNOPSIS...
Rain near the coast will slowly come to an end today as low
pressure southeast of New England will moves farther out to
sea. Weak high pressure will build over the region Monday and
Tuesday, but continued onshore winds should keep cloudiness
over southern New England, especially near the coast. Rain
chances increase again around midweek as a front approaches from
the Great Lakes.

&&

.NEAR TERM /THROUGH TONIGHT/...
The last few runs of the HRRR and RAP matched regional radar
data well for the initialization hours, and used those sources
to tweak rainfall chances this morning. Rainfall was shunted a
little farther south this morning, but expecting another round
of lower clouds and showers across southeast MA later this
morning. Still thinking more improvement for this afternoon, at
least temporarily. Gusty NE winds continue. Minor tweaks to
temperatures to bring them back in line with observed trends.

Previous Discussion...

Slow improvement is the theme for today`s forecast as offshore
low takes its time heading farther out to sea. Radar trends
continue to show erosion of its rain shield over eastern MA as
drier air aloft is working into region from north, and as
surface ridging continues to take hold today, we should see rain
continue to diminish, but probably not until around sunrise in
most of eastern MA and later this morning near Cape Cod and
Islands. It`s possible we even see some breaks of sunshine this
afternoon.

Farther west, there`s still enough low level moisture present to
maintain at least some cloudiness today, but certainly better
chances of seeing sun break out as you head toward the CT River
Valley and east slopes of the Berkshires.

Still a windy day across SE MA, especially on Cape Cod and
Islands where 25-35 mph gusts are expected most of the day.

&&

.SHORT TERM /MONDAY/...
Ridging at surface and aloft begins to take hold tonight and
Monday leading to drier weather overall. Model cross sections
still show plenty of lower level moisture, however, especially
near coast tonight which should result in low clouds and
possibly some drizzle as well. Clouds should dominate Monday but
expect breaks of sun, especially inland.

&&

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

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

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

High pressure centered over the Saint Lawrence River will nudge
its way across southern New England. While keeping the forecast
mainly dry into Wednesday, being on the southern periphery with
the weaker subsidence, along with the persistent onshore flow,
should result in plenty of clouds much of this week.

Wednesday still looks to be the transition day as this high
pressure moves farther east. Latest guidance suite has trended
slower with the arrival of showers, but may still not be quite
slow enough given the synoptic pattern. Starting to think much
of Wednesday will be dry as well, especially across the eastern
half of southern New England. Only have moderate confidence in
the current forecast timing.

Still looking more unsettled toward the end of next week as a
low pressure passes by our region. Plenty of uncertainty in the
details, but there is still plenty of time to refine the
forecast timing.

The persistent easterly onshore flow will maintain at least an
elevated risk for rip currents and rough surf into Tuesday.

&&

.AVIATION /11Z SUNDAY THROUGH THURSDAY/...
Forecast Confidence Levels:

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

12Z Update: Moderate confidence (40%) due to timing of
ceilings.

Rain and IFR ceilings near Cape Cod and Islands will linger
past sunrise before rain tapers off and ceilings improve to
MVFR where they should remain all day with NE winds gusting to
25-30kt. Rain will diminish before sunrise in much of RI and
eastern MA where MVFR ceilings should lift to VFR for a few
hours before returning 12-15z, then improving to VFR again
during afternoon. Farther west, VFR ceilings prevail except near
KORH where IFR ceilings improve to MVFR this morning and to VFR
this afternoon.

VFR tonight, but coastal areas should see MVFR ceilings with
possible drizzle at times. Improvement to VFR Monday, but
probably not until early afternoon near coast with continued NE
winds, although lighter.

BOS TAF...Moderate confidence due to timing of ceiling changes.
MVFR ceilings may not return as quickly as forecast this morning
and again tonight.

BDL TAF... High Confidence.

Outlook /Monday Night through Thursday/...

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

Tuesday: Mainly VFR, with areas MVFR possible. Breezy.

Tuesday Night: Mainly VFR, with areas MVFR possible.

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

Wednesday Night: Mainly VFR, with local IFR possible. Chance
SHRA.

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.

Overall high confidence through Monday. Maintaining SCA
headlines for all waters except Boston Harbor and Narragansett
Bay.

Low pressure offshore remains close enough today to maintain
strong NE winds gusting to 25-30kt, with strongest gusts around
Cape Cod and Islands where some marginal Gales are possible at
times today. NE winds gradually subside tonight and Monday as
low heads farther SE away from region but rough seas should
persist, especially on open waters.

Rain gradually diminishes today but may linger most of day on
waters south and east of Cape Cod.

Outlook /Monday Night through Thursday/...

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. Areas of rough seas.
Chance of rain showers.

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

&&

.TIDES/COASTAL FLOODING...
Coastal Flood Advisory remains in effect for afternoon high
tide today. While astronomical tides remain elevated, the tides
are slowly coming down from the peak Fri and Sat. Still
expecting a surge of 1-1.5 ft which will result in shallow
flooding less than one foot deep of more vulnerable locations.

High Surf Advisory remains posted due to high seas and rough
surf which will continue today.

&&

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

&&

$$

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