399
FXUS61 KBOX 050536
AFDBOX

Area Forecast Discussion
National Weather Service Boston/Norton MA
136 AM EDT Fri Sep 5 2025

.SYNOPSIS...
Warm and humid conditions briefly return to the region Friday and
Saturday, ahead of an approaching cold front. The cold
front brings the risk of scattered showers and thunderstorms
Saturday afternoon and evening...mainly across the interior. There
is the potential for some severe weather Saturday afternoon and
evening across interior southern New England. Some showers may
linger behind the cold front late Saturday night into part of
Sunday as much cooler & less humid air works into the region.
Dry and beautiful weather is expected for the first half of next
week with cool nights and mild days.

&&

.NEAR TERM /UNTIL 6 AM THIS MORNING/...
Key Messages:

* Pleasant temps and increasing dewpoints

* Warm front moves through with scattered showers overnight

Overnight, a weakening cold front extending south from an area of
low pressure over Ontario approaches the area. Guidance indicates a
batch of elevated showers and isolated thunderstorms ahead of this
feature. Generally agree with this as there will be some elevated
instability (MLCAPE ~200-300 J/kg). Best areal coverage of showers
will be found across northwest and central Massachusetts before the
majority of the activity decays as it moves east. Rain totals should
be light with ensemble guidance generally showing >0.25" of QPF for
most locations. Low temperatures will run near average, generally
falling into the upper 50s and low 60s.

&&

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

* Warm and muggy day Friday

* Increasing winds w/ gusts up to 25 mph by the afternoon

Outside of a lingering shower on Friday morning, rest of the day is
shaping up to be a dry one. A few warm advection showers cannot be
ruled out for areas north of Route 2 in northern Massachusetts, as
the best forcing is across northern New England. Otherwise, it`s a
warm and muggy afternoon, a blend of clouds and sun. Temperatures
reach the low to middle 80s, the south coast remains less warm with
highs in the upper 70s to 80F. Dew points are noticeably higher and
range between the low 60s across interior locations with middle to
upper 60s for the coastal plain. Additionally, BUFKIT profiles show
a deep mixed layer as high as 850mb across the interior. Increasing
gradient flow in this thermodynamic environment could favor 10-15
mph sustained winds with gusts as high as 30 mph. Increasing
pressure gradient Friday night between an approaching cold front to
the west and departing high pressure keeps breezy conditions going.
Temps will likely be above average, only falling into the lower to
mid 60s for much of the region.

&&

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

* Breezy, warm & humid Sat with highs well into the 80s
* Scattered severe t-storms possible Sat PM...mainly in the interior
* Some showers persist overnight Sat into Sun & turning much cooler
* Dry weather with cool nights & mild days first half of next week

Details...

Saturday...

the main concern revolves around the severe weather threat Saturday
afternoon and evening...mainly across the interior which we will
discuss in the following paragraph. Otherwise...a brief return to
summerlike weather is in store for Saturday. Southwest flow ahead of
an approaching cold front will allow a return of low level moisture
and some humidity too. In fact...modest southwest LLJ and good
mixing shield yield SW wind gusts of 20-30 mph by afternoon with
even a few gusts near 35 mph. 850T around +16C with partial sunshine
will allow highs to reach the middle to upper 80s away from the
immediate south coast, Cape, and Islands.

As mentioned earlier...the main concern is the potential for
scattered severe thunderstorms Saturday afternoon and evening. This
risk will be mainly across the interior. The return of low level
moisture and heating ahead of the approaching cold front should
yield 1000 to 2000 J/KG of Cape...despite poor mid-level lapse
rates. Wind fields are looking impressive and SPC SREF indicating
modest probabilities of Capes of 1000+ J/KG overlapping with
effective shear of 40+ knots which is often a good signal. The CSU
machine learning probabilities also indicated a severe weather risk
across interior southern New England. The best forcing will remain
northwest of I-95 through 00z Sunday...so thinking that the main
severe weather risk will be across the interior. In fact...much of
the I-95 corridor may remain dry into early Saturday evening.

The main severe weather risk will be strong to damaging straight
line wind gusts given the amount of effective shear. That being
said...there is also modest 0-1 KM helicity and the SPC SREF does
have the significant tornado parameter highlighted across the
interior. While that does not mean there will be a tornado...it
often indicates a severe weather risk and flags at least the low
risk for a tornado exists. Something will need to watch closely.

Late Saturday night and Sunday...

The cold front will be slow to progress east giving the upper level
ridge over the Atlantic. Some of the guidance also indicates a
period of southwest flow aloft lingering even behind the cold front
with an anafrontal wave. This could yield some anafrontal showers
late Saturday night into at least the first half of Sunday. It will
also be turning quite a bit cooler and less humid behind the cold
front for Sunday. Highs on Sunday will probably be only in the lower
70s for much of the region.

Monday through Thursday...

A large ridge of high pressure builds in from the west for the first
half of next week. This will result in dry weather with slightly
cooler than normal temperatures...but beautiful early September
weather. Cool nights with lows mainly in the 40s to the lower 50s
and mild days with highs mainly in the lower to middle 70s along
with comfortable humidity.

&&

.AVIATION /06Z FRIDAY THROUGH TUESDAY/...
Forecaster Confidence Levels...

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

06z TAF Update...

Through 12z... Moderate Confidence.

VFR deteriorate to mainly MVFR from west to east overnight from low
clouds with the returning low level moisture. Localized IFR are also
possible toward morning across parts of the interior. S wind 5-10
knots.

Today... High Confidence.

Becoming VFR by mid to late morning. Breezy, SSW wind 10-15 knots
with gusts around 25 knots. A few brief gusts approaching 30 knots
are also possible during the afternoon.

Tonight... High Confidence.

VFR, areas of MVFR are possible across south coast, Cape Cod, and
the Islands. SW wind 8-12 knots.

Saturday... Moderate Confidence.

VFR, becoming MVFR with afternoon thunderstorms. Area of greatest
risk for strong to severe storms are interior southern New England
terminals. Gusty SSW wind 10-15 knots, gusting 25 knots.

KBOS Terminal...High confidence in TAF.

KBDL Terminal...High confidence in TAF.

Outlook /Saturday Night through Tuesday/...

Saturday: Mainly VFR, with local MVFR possible. Breezy. Chance
SHRA, chance TSRA.

Saturday Night: Mainly MVFR, with areas VFR possible. Breezy.
Chance SHRA, isolated TSRA, patchy BR.

Sunday: Mainly VFR, with areas MVFR possible. Chance SHRA,
patchy BR.

Sunday Night through Tuesday: VFR.

&&

.MARINE...
Forecaster Confidence Levels...

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

Through Friday... High Confidence.

Area of high pressure moves east of the coastal waters today with
increasing S to SE winds of 10-15 knots with occasional gusts less
than 25 knots. Seas today are increasing 3-4 feet. A few showers are
possible overnight into Friday morning and areas or marine fog.

Wind shifts to the SSW for Friday, sustained winds are 15-20 knots,
with gusts 25-28 knots. Seas on the outer waters are building 4-5
feet and near shore waters are 3-4 feet. Conditions are marginal for
a Small Craft Advisory, no headlines will be issued now, but could
be issued during subsequent forecast updates.

Outlook /Saturday Night through Tuesday/...

Saturday: Low risk for Small Craft Advisory winds with gusts up
to 30 kt. Seas up to 5 ft.

Saturday Night: Winds less than 25 kt. Areas of seas
approaching 5 ft. Chance of rain showers, patchy fog.

Sunday: Winds less than 25 kt. Seas locally approaching 5 ft.
Chance of rain showers, patchy fog.

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

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

Monday Night through Tuesday: Winds less than 25 kt.

&&

.BOX WATCHES/WARNINGS/ADVISORIES...
CT...None.
MA...None.
RI...None.
MARINE...Small Craft Advisory from 11 AM this morning to 7 PM EDT this
     evening for ANZ230-236.
     Small Craft Advisory from 11 AM this morning to 8 PM EDT
     Saturday for ANZ231>235-237-250-251-254>256.

&&

$$

SYNOPSIS...Frank/FT
NEAR TERM...FT
SHORT TERM...FT
LONG TERM...Frank
AVIATION...Frank/Dooley/FT
MARINE...Frank/FT