053
FXUS61 KBOX 220757
AFDBOX

Area Forecast Discussion
National Weather Service Boston/Norton MA
357 AM EDT Fri Aug 22 2025

.SYNOPSIS...
Hurricane Erin will pass well southeast of Nantucket today,
with the only impacts being limited to southeast coastal New
England. High surf and dangerous rip currents along with areas
of coastal flooding and beach erosion are anticipated on south-
facing beaches. Dangerous marine conditions from gale force wind
gusts and high offshore waves, and potential minor coastal
flooding are also expected impacts, though winds will continue
to diminish through the day today. Seasonable weather expected
today and Saturday with breezy conditions. Turning more
unsettled for Sunday night through Monday chances for showers
and thunderstorms before dry weather returns midweek.

&&

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

* Winds gradually diminish across the region today, including over
  the Cape and Islands as Erin continues to the northeast

* High surf, dangerous rip currents, coastal flooding, and the
  chance for beach erosion continue

Erin made its closest pass to southern New England this morning and
will continue its track to the northeast away from the coasts.
Erin`s influence is expected to continue to diminish today, with the
pressure gradient between it and the high over New England beginning
to slacken. Winds will be the first to decrease, first across the
interior then coming down to 10 mph and less over the Cape and
Islands heading into tonight. However, the chance for beach erosion,
threats from high surf, coastal flooding, and dangerous rip currents
will continue a bit longer. More details regarding coastal flooding
and beach erosion can be found in the coastal flooding section of
this discussion.

High pressure maintains its influence over the region with dry
conditions aloft and at the surface. Highs today will be higher than
yesterday with clearer skies allowing temperatures to rise into the
low 80s across southern New England.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM SATURDAY/...
Key Messages:

* Evening high tides tonight will carry the risk for coastal
  flooding in some areas

* Warmer, more seasonable temperatures to start the weekend as south
  to southwest winds kick in

With Erin off and away from the coasts, winds will go light across
all of the region tonight. Lows are expected to stay above the mid
50s even with clearer skies and lighter winds. Minor coastal
flooding in more vulnerable spots will remain possible with the high
tide cycle tonight, along with higher surf and dangerous rip
currents through Saturday.

Another area of high pressure will pass along the east coast through
the day Saturday, encouraging some breezier S to SW flow. The
warming trend continues with more seasonable highs up to the mid
80s.

&&

.LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/...
Key Messages:

* Lingering coastal and marine threats from Erin will start to
  diminish Saturday night

* More seasonably normal temperatures continue through the weekend

* Unsettled conditions expected for the start of next week as a cold
  front approaches

High surf and dangerous rip currents will start to decrease Saturday
night into Sunday as Erin continues to move into the North Atlantic.
Seasonable temperatures continue into Sunday as 925 mb temperatures
remain around 20C and mix to the surface. Lows rise into the low 60s
for Sunday night.

The pattern turns more unsettled Sunday through Monday night as a
cold front approaches the region. Guidance is increasingly
indicating that this front may end up stalling over the Mid Atlantic
before moving towards southern New England Sunday night. Southerly
winds will also amplify ahead of this front Sunday afternoon and the
chances for rain increase for Monday. Forcing from the passing front
coupled with CAPE values exceeding 500 J/kg could lead to some
rumbles of thunder Monday afternoon; ensembles and deterministic
guidance continue to hint at the chance for some thunderstorms with
these signals. Whether some of these turn severe or not is still
undetermined. High pressure makes a return following the cold
front`s passage, leading to a more quiet week. High temperatures
dip more into the mid 70s midweek as a cooler post-frontal
airmass remains over the region.

&&

.AVIATION /08Z FRIDAY THROUGH TUESDAY/...
Forecaster Confidence Levels...

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

06z Update...

Through 12z...High confidence.

VFR. N to NE winds continue to gust over PVD 20-25 kts tonight,
with more infrequent ones possible over BOS. These have now
diminished over interior terminals. Stronger gusts up to 40 kts
for the Cape/Islands expected to remain possible.

Friday...High confidence.

VFR. N winds sustained at 10 kts across much of the region,
25 kts over the Cape and Islands in the morning. Gusts start
around 20 kts for BOS/PVD and up to 40 kts over the Cape and
Islands before overall winds diminish heading into the afternoon
and evening.

Friday Night...High confidence.

VFR. Winds become light overnight, varying between S and W.

Saturday...High confidence.

VFR. Winds from the S/SSW up to 10 kts with occasional gusts
close to 20 kts over eastern MA.

KBOS Terminal...High confidence in TAF.

KBDL Terminal...High confidence in TAF.

Outlook /Saturday Night through Tuesday/...

Saturday Night: VFR. Breezy.

Sunday: VFR. Breezy. Slight chance SHRA.

Sunday Night: Mainly VFR, with local MVFR possible. Breezy.
Chance SHRA.

Monday: Mainly VFR, with local IFR possible. Chance SHRA,
chance TSRA.

Monday Night: VFR. Chance SHRA.

Tuesday: VFR. Breezy.

&&

.MARINE...
Forecaster Confidence Levels...

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

Through Saturday...High confidence.

Seas will begin to diminish today, continuing to fall through
Saturday down to more Small Craft Advisory conditions. Seas in
the outer waters will be around 8 ft by tonight, then down to 5
ft in spots by Saturday.

A High Surf Advisory remains in effect for southern coastal
areas, including the Cape and Islands. Waves will gradually
decrease Friday, though they will still be 10-15 ft offshore.
Rip currents will stay a significant concern with the elevated
surf through at least the first half of the weekend. High Surf
Advisories continue through Saturday evening.

A Gale Warning will remain in effect through Friday afternoon
with potential for gusts to 40 kts as the gradient between the
high pressure over southern New England and passing Erin will
tighten greatly. With Erin having passed this morning, winds
will start to diminish during the day but will still be gusty
until tonight. Elsewhere will see Small Craft Advisories to
cover the high waves and elevated wind gusts.

Outlook /Saturday Night through Tuesday/...

Saturday Night: Winds less than 25 kt. Seas up to 5 ft.

Sunday: Low risk for Small Craft Advisory winds with gusts up
to 25 kt. Seas up to 5 ft.

Sunday Night: Winds less than 25 kt. Areas of seas approaching
5 ft. Chance of rain showers.

Monday: Winds less than 25 kt. Seas locally approaching 5 ft.
Chance of rain showers.

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

Tuesday: Winds less than 25 kt. Local rough seas.

&&

.TIDES/COASTAL FLOODING...
Key Messages:

* Significant beach and dune erosion on south facing ocean
  beaches.

* Minor coastal flooding for Martha`s Vineyard, Nantucket, and
  MA/RI South Coast including Narragansett Bay.

The main concern is for significant beach and dune erosion along
south facing ocean beaches, especially along the south coasts of
Martha`s Vineyard and Nantucket, as well as South County (RI)
due to persistent long-period southerly swells that will peak on
Friday, before slowly subsiding Saturday. Offshore buoys are
already showing significant wave heights around 15 ft at periods
of 10-15 seconds, which is indicative of a lot of swell energy.

Breaking waves on the ocean beaches could get as high as 15 to
20 feet resulting in significant beach and dune erosion or
loss. It is tough to determine how much loss could occur but
this could rival what we normally see with stronger nor`easters
during the winter. Both of these islands and the South Coast
have already seen significant beach, dune, and shoreline loss
over the past few winters and are especially vulnerable to
further loss.

Regarding coastal flooding, we`ve added South Coastal MA/RI,
including Narragansett Bay communities, to the Coastal Flood
Advisory. The high tides of concern are Friday morning and
especially Friday evening when we should see a storm surge of 1
to 2 feet (2 feet being the higher end). Normally we`re not
concerned with the South Coast with an offshore (N/NE) wind, but
the combination of persistent southerly swell and the large
envelope of wind on the fringes of Hurricane Erin are expected
to be sufficient to produce this amount of surge.

Flooding should remain well within the Minor category with
flooding up to one foot deep confined to vulnerable shore
roads and low lying areas.

For Martha`s Vineyard and Nantucket, we expect a similar surge
of 1 to perhaps 2 feet during high tides late tonight and late
Friday night. Minor coastal flooding (up to one foot deep)
should occur in the more vulnerable sections of Nantucket
Harbor, Edgartown Harbor, Vineyard Haven, and Oak Bluffs around
high tide. Seas up to 8 feet on Nantucket Sound could bring some
debris onto coastal roads such as Seaview Avenue in Oak Bluffs
near the seawall.

Along the E MA coast including Cape Cod, no significant coastal
flooding is expected but water levels could reach Action stage
due storm surge of 1 to 1.5 ft combined with somewhat high
astronomical tides. We would be more concerned if we had
stronger pressure falls and higher surge ahead of the hurricane,
or higher seas into the eastern MA waters, which are all
unlikely given the track well offshore.

&&

.BOX WATCHES/WARNINGS/ADVISORIES...
CT...None.
MA...High Surf Advisory until 8 PM EDT Saturday for MAZ007-019>024.
     Coastal Flood Advisory until 10 AM EDT this morning for MAZ020.
     Coastal Flood Advisory from 6 PM to 10 PM EDT this evening for
     MAZ020.
     Wind Advisory until 2 PM EDT this afternoon for MAZ022>024.
     Coastal Flood Advisory from 10 PM this evening to 2 AM EDT
     Saturday for MAZ023-024.
RI...High Surf Advisory until 8 PM EDT Saturday for RIZ006>008.
     Coastal Flood Advisory until 10 AM EDT this morning for RIZ002-
     004>008.
     Coastal Flood Advisory from 6 PM to 10 PM EDT this evening for
     RIZ002-004>008.
MARINE...Small Craft Advisory until 2 PM EDT this afternoon for ANZ230-
     236.
     Gale Warning until 8 PM EDT this evening for ANZ231-232-250-
     254-255.
     Gale Warning until 2 PM EDT this afternoon for ANZ233>235-237-
     256.
     Small Craft Advisory until 8 PM EDT this evening for ANZ251.

&&

$$

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