963
FXUS61 KBOX 121841
AFDBOX

Area Forecast Discussion
National Weather Service Boston/Norton MA
241 PM EDT Sun Oct 12 2025

.SYNOPSIS...
A coastal storm brings rain and strong coastal winds into Monday
night, along with the minor coastal flooding and erosion.
Coastal low then begins to pull away for Tuesday, with decreasing
rains and easing northerly winds. However an unseasonably cool
airmass brings dry weather with below normal temperatures and a
return of breezy northwest winds for mid to late next week.
Temperatures then rebound back to above normal levels for the
weekend.

&&

.NEAR TERM /THROUGH MONDAY NIGHT/...
Key Messages:

* Rain, heavy at times tonight into Monday with additional heavy
  rain Mon night across eastern MA

* Gusty NE winds peak tonight into Monday morning. Strongest winds
  over Cape/Islands where gusts to 50+ mph expected with some power
  outages possible

* Pockets of minor coastal flooding during high tide

The brunt of the wind and rain impacts from this coastal storm will
be felt tonight into Monday, although potential for heavy rain will
linger into Mon night across eastern MA. Strong moisture inflow and
convergence from easterly low level jet acting on PWATs 150-200% of
normal will result in widespread rainfall which will fall heavy at
times. Duration will be a factor to realizing heavy rainfall amounts
as blocking ridge over Maritimes keeps coastal low will be quasi-
stationary off the mid Atlc coast.

Rainfall...

Rain shield is slowly lifting north along the coast but steadier
rain struggling to move into the interior as there is a dry layer in
the low levels that will need to be overcome. The leading edge of
the steady rain will gradually overspread the interior through the
afternoon while heavier rain develops over the Cape/Islands.
Heaviest rain will be tonight and Monday, with locally heavy rain
lingering into Mon night across eastern MA. Deep moisture plume sets
up across SNE tonight with increasing low level frontogenesis during
Monday as the 850 mb front lifts north into SNE. Rain will gradually
become more convective during Monday as elevated instability
increases at the edge of a pseudo dry slot. Best chance of heavier
convective showers and possible elevated thunder will be Monday
afternoon and night, mainly eastern MA where heaviest rain is
expected. HREF indicating 30 percent probs of 3 hr rainfall of 1"+
in eastern MA Mon afternoon, increasing to 50-70 percent across SE
coastal MA and Cape/Islands Mon night. Rainfall will being to taper
off in western New Eng Mon night, but convective showers will
persist in eastern MA. Heaviest storm total rainfall through Tue
will be across eastern MA/RI where widespread 2-3 inch amounts are
expected, but locally 4-5 inches is possible in eastern MA. Hi-res
guidance is targeting the eastern MA coast where locally heavy
convective showers may contribute to higher amounts. Since the
rainfall will be spread out over 48+ hours, significant flooding
impacts are not expected, although some minor poor drainage street
flooding is possible. Lesser rainfall amounts in western New Eng.

Strong winds...

No changes to the wind forecast. Strongest winds will be tonight
into Mon morning across the Cape/Islands which will be within the
axis of a gradually weakening 60-65 low level jet. Soundings show a
shallow mixed layer supporting wind gusts to 50-60 mph over the
Islands and up to 50 mph over Cape Cod. No changes to wind
headlines. As the jet weakens as it lifts northward into SNE wind
gusts will be less across rest of SNE with gusts to 35-45 mph along
the immediate coast and 25-35 mph further inland.  Given most trees
remain fully leaved, some tree damage and power outages are
possible, mainly over the Cape and Islands.

Winds will diminish Mon afternoon through Mon night as the low level
jet continues to weaken, but winds will remain gusty along the
coast.

&&

.SHORT TERM /TUESDAY THROUGH TUESDAY NIGHT/...
Key Messages:

* Rain with northeast to northerly breezes continue Tue, easing Tue
  night.

Details:

Still contending with lingering impacts from the coastal storm Tue,
in the form of continued areas of rain and northerly breezes. The
character of the rain trends more intermittent or even drizzle as
drier air aloft works in on the northwest periphery of the coastal
low`s circulation; steady light rains continuing for eastern/coastal
MA and portions of eastern RI. NE to N winds gusting around 20-25
mph, but still up to 30 mph over the Cape and Islands during the
day. Highs mid 50s to lower 60s are cooler than normal but will feel
quite a bit cooler with the continued northerly breezes.

Coastal low then finally pulls away Tue evening; rain then starts to
taper off Tue night from W to E, although intermittent showers may
still hold on overnight across the Cape and Islands. N to NW wind
gusts will also be easing up Tue evening as well. Still possible
we`ll have to watch for splashover around Nantucket for the Tue
evening high tide, but easing NW winds lead to somewhat lower storm
surge values at around a foot; with astro tide of 3.81 ft and would
need a little higher storm surge to get to minor. Lows mid 40s to
lower 50s.

&&

.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
Key Messages:

* Below normal temps Wed thru Fri, with cloudy conditions and gusty
  north winds returning near the Cape and Islands. Minor coastal
  flooding possible for Nantucket.

* Pattern change toward above normal temps by next weekend.

Details:

Wednesday through Friday:

While the coastal low from the weekend/early in the week slowly
meanders in the Canadian Maritimes early on Wed, a deep upper trough
establishes itself over the Northeast. This feature per good
agreement in ensembles, "catches" the coastal low and begins to pull
it north or north-northwest toward Nova Scotia, which helps to
tighten the NW pressure gradient again. This deep upper trough also
ushers in an unseasonably cool airmass for mid to late in the week.

Blustery and dry weather with below normal temperatures can be
expected in this period for the interior and coastal plain. However
some greater impacts for the Cape and Islands: below normal temps
are expected here too, but will also be accompanied by cloudy
weather, stronger north/northwest winds even some ocean-effect
showers possible. Northerly winds could gust up to 30 mph over land,
with gusts to gale force over the waters. These stronger northerly
winds could also lead to renewed minor coastal flooding Wed-Thu for
at least Nantucket and possibly some splashover for areas around
Cape Cod Bay. High temps in the mid 50s though it may feel like the
40s with the breezes.

Next Weekend:

Significant pattern change indicated in ensembles in this forecast
period as the deep upper trough moves offshore, and allows for
strong 500 mb height rises and warmer temps to return. Full sun and
dry weather are expected for the weekend. However 850 mb temps rise
to above +10C by Sunday! Depending on how deep we can mix to, we may
go from highs in the 50s Thurs to well into the 70s by the
weekend.

&&

.AVIATION /18Z SUNDAY THROUGH FRIDAY/...
Forecaster Confidence Levels...

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

Today: High confidence in trends. Moderate confidence in
timing.

Continued deterioration toward MVFR-IFR through 20z from south
to north as wind-driven rain moves in. Steady increase in E-NE
wind speeds to around 15 kt with gusts is the 20s kt range
interior airports. E-NE winds near the coastal airports pick up
to around 20-25 kt with gusts to 35 kt by this afternoon, with
gusts 35-40 kt Cape and Islands.

Tonight through Monday: High confidence in trends but lower
confidence on the timing.

IFR-LIFR ceilings with IFR-MVFR visibilities in steady rain.
Rain could lighten up some for the interior airports later Mon.
E-NE winds 15-25 kt with gusts 25-30 kt inland, and around 35-50
kt near the coasts. Strongest gusts over the Cape and Islands.
Strong LLWS up to 60 kt possible, especially towards the Cape
and Nantucket tonight into Monday morning.

KBOS Terminal...High confidence in TAF trends. Moderate confidence in
timing.

KBDL Terminal...High confidence in TAF trends. Moderate confidence in
timing.

Outlook /Wednesday through Friday/...

Wednesday: VFR. Breezy.

Wednesday Night: VFR. Windy with local gusts up to 30 kt.

Thursday through Thursday Night: VFR. Windy with gusts up to
35 kt.

Friday: VFR. Windy with local gusts up to 30 kt.

&&

.MARINE...
Forecaster Confidence Levels...

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

Storm and Gale warnings continue across the coastal waters into
Monday. Expecting the strongest winds tonight, with gradual
improvement Monday. Visibility reduced in rain and fog into Mon.
Seas of 15-20 ft expected across the outermost coastal waters.

Outlook /Wednesday through Friday/...

Wednesday: Low risk for Small Craft Advisory winds with local
gusts up to 30 kt. Areas of rough seas. Slight chance of rain
showers.

Wednesday Night: Strong winds with gusts up to 30 kt. Rough
seas up to 9 ft. Chance of rain showers.

Thursday: Strong winds with gusts up to 45 kt. Rough seas up to
10 ft. Chance of rain showers.

Thursday Night: Moderate risk for gale force winds with gusts
up to 40 kt. Rough seas up to 11 ft. Chance of rain showers.

Friday: Low risk for gale force winds with gusts up to 35 kt.
Areas of rough seas. Slight chance of rain showers.

&&

.TIDES/COASTAL FLOODING...
The biggest impact from this coastal storm will be beach
erosion as significant wave action impacts the next 2 high tide
cycles tonight into Monday.

Storm surge along the RI south coast has been slower to ramp up
and as a result little to no inundation occurred at high tide
earlier this afternoon along the RI coast. The high tide along
the east coast is later this afternoon and expect minor
splashover here from the combination of a 1-1.5 ft surge and
wave action. The greatest impacts will be over Nantucket and
Edgartown on Martha`s Vineyard where a surge around 1.5 ft is
expected. Current surge at Nantucket is 1.3 ft.

The high tide tonight is lower, especially along the eastern MA
coast where inundation is not expected. However, higher surge and
waves will likely lead to minor inundation at Nantucket, Marthas
Vineyard and ocean exposed RI south coast.

The Monday afternoon high tide is also expected to be impacted
with widespread minor inundation along the east coast and
ocean exposed RI south coast. Storm surge of 1.5-2 ft will
coincide with the highest seas during this time.

Coastal Flood Advisories for future tides of concern will likely
be issued with later forecasts as we move past each high tide
where inundation is possible.

&&

.BOX WATCHES/WARNINGS/ADVISORIES...
CT...None.
MA...Coastal Flood Advisory until 6 PM EDT this evening for MAZ007-
     015-016-019-022>024.
     Wind Advisory until 8 PM EDT Monday for MAZ022.
     Coastal Flood Advisory from 4 AM to 8 AM EDT Monday for MAZ023-
     024.
     High Wind Warning until 2 PM EDT Monday for MAZ023-024.
RI...High Wind Warning until 2 PM EDT Monday for RIZ008.
     Coastal Flood Advisory from midnight tonight to 4 AM EDT
     Monday for RIZ006>008.
MARINE...Gale Warning until 8 PM EDT Monday for ANZ230-233-234.
     Gale Warning until 2 AM EDT Tuesday for ANZ231-250-251-254.
     Storm Warning until 8 AM EDT Monday for ANZ232-235-237-255-256.
     Gale Warning until 2 PM EDT Monday for ANZ236.

&&

$$

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