Area Forecast Discussion
Issued by NWS Boston, MA

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429
FXUS61 KBOX 130819
AFDBOX

Area Forecast Discussion
National Weather Service Boston/Norton MA
419 AM EDT Mon Oct 13 2025

.SYNOPSIS...
A coastal storm brings rain and strong coastal winds into tonight,
along with the minor coastal flooding and erosion. This coastal
low then begins to move farther offshore 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 this week. Temperatures then rebound back to above normal
levels for this weekend.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
Key Messages:

* Rain, heavy at times today, with additional heavy rain tonight
  across portions of eastern MA

* Gusty NE winds peak this 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

No significant changes to the ongoing forecast. Did make some
tweaks to timing based on the latest guidance suite. Thinking
rainfall chances decrease more quickly this afternoon across the
western half of southern New England. That said, it`s not to be
taken that it will be completely dry. Expecting up to an
additional 0.75 inch of rainfall across the western half of our
region today. Farther east, rainfall up to 1.50 inches is
expected, especially across portions of southeast MA. Nay
actually see a little break in the rainfall towards the Cape and
islands this morning, which will help to lower rainfall totals
there today.

Still not overly concerned about the possibility of
thunderstorms today, but the risk is not negligible. The most
likely area would be across southeast MA, and perhaps RI.
Thinking the nature of the precipitation will be more showery
than stratiform. So there should be some periods of drier
weather between these showers.

No changes to the wind forecast into this morning, at least for
now. Thinking the High Wind Warning can be downgraded later
this morning. Will let a later shift fine-tune the timing of any
such change. Given most trees remain fully leaved, some tree
damage and power outages are possible, mainly over the Cape and
Islands.

&&

.SHORT TERM /6 PM THIS EVENING 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
tonight into Tuesday night, 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 this 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 Tuesday evening; rain then
starts to taper off Tuesday 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 Tuesday 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 flood stage.

&&

.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 /07Z MONDAY 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 but lower confidence on the
timing.

IFR-LIFR ceilings with IFR-MVFR visibilities in steady rain
becoming more shower later this morning. 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 this
morning.

Tonight and Tuesday: High confidence in trends but lower
confidence in the timing.

IFR/LIFR ceilings tonight become MVFR/IFR late Tuesday morning
into the afternoon. Coverage of showers decreasing across
the interior, but still widespread towards eastern MA. gusty N
to NE winds continue, but not as strong as today.

Tuesday Night: High confidence.

MVFR ceilings becoming VFR. Decreasing N to NW winds.

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 through Wednesday Night: VFR. Breezy. Slight chance
SHRA.

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

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
this morning. Will likely downgrade the Storm Warnings to Gale
Warnings later this morning. Expecting winds below gale force by
sometime Tuesday morning. Visibility reduced at times in rain
and fog. Rough seas gradually decrease across the outer coastal
waters into Tuesday night.

Outlook /Wednesday through Friday/...

Wednesday: Low risk for Small Craft Advisory winds with gusts
up to 30 kt. Areas of rough seas. 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 40 kt. Rough seas up to
10 ft. Chance of rain showers.

Thursday Night: Strong winds with gusts up to 40 kt. Rough seas
up to 11 ft. Chance of rain showers.

Friday: Moderate risk for Small Craft Advisory winds with gusts
up to 30 kt. Rough seas up to 11 ft. 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 high tide cycles
today.

This afternoon`s 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...Wind Advisory until 8 PM EDT this evening for MAZ022.
     High Wind Warning until 2 PM EDT this afternoon for MAZ023-024.
     Coastal Flood Advisory until 8 AM EDT this morning for MAZ023-
     024.
     Coastal Flood Advisory from 3 PM this afternoon to 7 PM EDT
     this evening for MAZ023-024.
RI...High Wind Warning until 2 PM EDT this afternoon for RIZ008.
     Coastal Flood Advisory from noon today to 4 PM EDT this
     afternoon for RIZ006>008.
MARINE...Gale Warning until 8 PM EDT this evening for ANZ230-233-234.
     Gale Warning until 2 AM EDT Tuesday for ANZ231-250-251-254.
     Storm Warning until 8 AM EDT this morning for ANZ232-235-237-
     255-256.
     Gale Warning until 2 PM EDT this afternoon for ANZ236.

&&

$$

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