248
FXUS61 KBOX 030611
AFDBOX

Area Forecast Discussion
National Weather Service Boston/Norton MA
211 AM EDT Thu Sep 3 2026

.WHAT HAS CHANGED...
In addition to the risk for dangerous rip currents this Holiday
Weekend there will be a risk for Small Craft Advisory conditions
on Sunday.

&&

.KEY MESSAGES...

- Rounds of showers and thunderstorms impact the region today. The
first arrives this morning and the second arrives later in the
afternoon.

- Mainly dry & very pleasant Fri into early next week except for
some diurnally scattered showers mainly on Sat. Pleasant temps too
with highs in the 70s...but lower-middle 80s Fri.

- Elevated risk for dangerous rip currents for the Holiday Weekend
especially by Sun into Mon.


&&

.DISCUSSION...
KEY MESSAGE 1... Rounds of showers and thunderstorms impact the
region today. The first arrives this morning and the second arrives
later in the afternoon.

Impacts from a frontal wave continue through this morning with
scattered showers and thunderstorms possible. Activity overspreads
western parts of our CWA between 2 and 3 AM before it overspreads
the entire region by daybreak. Heavy downpours are likely with rich
moisture in place. There is a marginal risk for flash flooding
across western MA/CT in the Springfield/Hartford areas, but there is
no strong signal for anything overly impactful at this time.
Elevated instability will support some rumbles of thunder as showers
move across the region, but deep layer shear and low/mid-level lapse
rates do not appear to be favorable for deep moist convection
capable of producing strong to severe storms.

The passage of the frontal wave brings significant mid-level drying
with 700-500 mb RH values falling below 35 percent. The drier
airmass aloft will result in clearing and strong diurnal heating.
High temperatures will be warmer than they`ve been over the last
several days with widespread readings in the lower to mid 80s
likely. Warmer temps and dew points in the upper 60s to low 70s
result in CAPE values climbing to between 1500 and 2000 J/kg around
the region. Still, expecting any convection to be isolated to
scattered in nature with low mid-level RH values. High-Res guidance
has generally trended towards this solution with the NAM showing
isolated convection. The HRRR and RRFS are a bit more aggressive
and depict clusters of storms developing after 2 pm. Think the
NBM has a good handle on POPs with widespread values between 35
and 45 percent throughout the CWA. Greatest chance for any storm
activity will be along and S of a frontal boundary at it makes
its way SE. Guidance generally shows this boundary S of the Mass
Pike by 18z tomorrow thus, the greatest chance of storms will
likely be S of the Mass Pike.


KEY MESSAGE 2...Mainly dry & very pleasant Fri into early next week
except for some diurnally scattered showers mainly on Sat. Pleasant
temps too with highs in the 70s...but lower-middle 80s Fri.

Upper level shortwave energy will close off over the Canadian
Maritimes over the Holiday Weekend. This will carve out an upper
trough over the northeast resulting in pleasant weather. Mainly dry
weather expected over the majority of this time. However...some
northern stream shortwave energy will probably result in diurnally
driven scattered showers mainly on Sat...but can not rule out a few
on Fri. High pressure building southward from eastern Canada Sun
into Mon should bring an end to this risk for the latter half of the
Holiday Weekend. Highs on Fri will mainly be in the lower to middle
80s...but generally 70s to near 80 this weekend into early next
week. In fact...coolest days will be Sat and Sun as the eastern MA
coast/Cape and Islands probably only see highs in the upper 60s to
the lower 70s with a stiff northeast afternoon breeze. Overnight
lows mainly in the 50s to the lower 60s...but there might be some
40s in the normally coolest outlying locations by Sun night/Mon AM
as high pressure builds across the region.

KEY MESSAGE 3...Elevated risk for dangerous rip currents for the
Holiday Weekend especially by Sun into Mon.

Given persistent NE low level flow and swell...we do expect an
elevated risk for dangerous rip currents for the Holiday Weekend.
This is especially true by Sun into Mon on east facing ocean exposed
beaches.

&&

.AVIATION /06Z THURSDAY THROUGH MONDAY/...
Forecaster Confidence Levels...

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

06z TAF Update..

Through this Afternoon...High confidence in trends, moderate
confidence in timing.

First batch of showers continues to push into the area and will
make it to the BOS terminal by 07-09z. Ares of MVFR to IFR
conditions as well as heavy rainfall are possible with this
activity along with a few embedded t-storms. LLWS is also a
concern near daybreak given a modest southwest LLJ. Additional
areas of -SHRA and -TSRA are possible thru 14z as activity
continues to build across NY.

Bulk of the showers should exit the coast by mid-late morning.
We may see a few widely scattered showers/t-storms re-develop
during the afternoon...but areal coverage should remain
limited. Otherwise...gradual improvement should occur in
ceilings from west to east but timing remains uncertain. Some
locations especially northwest of I-95 may improve to VFR by
mid-late afternoon, but IFR conditions may persist well into the
afternoon near the Cape and Islands.

Southeast winds tonight gradually turn westerly on
Thursday...mainly at speeds of 6-12 knots or less.

Tonight...High Confidence.

Mainly VFR except low clouds may hang tough near the Cape and
Islands. In addition...we will need to watch for localized
patchy ground fog developing late in the typically prone
locations.

KBOS Terminal...Moderate confidence in TAF. Main concern for
showers and perhaps an embedded t-storm in the vicinity of the
terminal will be from 08z to 14z.

KBDL Terminal...Moderate confidence in TAF. Main concern for
showers and perhaps an embedded t-storm in the vicinity of the
terminal will be from now to 12z.

Outlook /Friday through Monday/...

Friday: VFR. Slight chance SHRA.

Friday Night: VFR.

Saturday: VFR. Breezy. Chance SHRA.

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

Sunday: VFR. Breezy.

Sunday Night through Labor Day: VFR.

&&

.MARINE...
Forecaster Confidence Levels...

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

Today through Friday Night

A frontal wave moves over the coastal waters early this
morning. This will be accompanied by heavy downpours and
possibly some thunder/lightning. Some locally stronger wind
gusts to 20 knots are possible, but otherwise expect modest but
steady southeast flow around 10 knots with gusts from 15 to 20
knots possible. Seas stay at sub SCY levels. Winds shift to the
west/northwest tomorrow afternoon and carry into Friday with
generally tranquil conditions. Tranquil conditions continue
overnight Friday as high pressure builds in.

Outlook /Friday through Monday/...

Friday: Winds less than 25 kt. Slight chance of rain showers,
patchy fog.

Friday Night: Winds less than 25 kt.

Saturday: Low risk for Small Craft Advisory winds with gusts up
to 30 kt. Areas of seas approaching 5 ft.

Saturday Night: Low risk for Small Craft Advisory winds with
gusts up to 30 kt. Local rough seas.

Sunday: Low risk for Small Craft Advisory winds with gusts up
to 25 kt. Areas of rough seas.

Sunday Night: Winds less than 25 kt. Local rough seas.

Labor Day: Winds less than 25 kt. Areas of seas approaching
5 ft.

&&

.BOX WATCHES/WARNINGS/ADVISORIES...
CT...None.
MA...None.
RI...None.
MARINE...None.

&&

$$

DISCUSSION...Frank/FT
AVIATION...Frank/FT
MARINE...Frank/FT