480
FXUS61 KBOX 051736
AFDBOX

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

.SYNOPSIS...
Warm and humid conditions briefly return to the region Friday and
Saturday, ahead of an approaching cold front. A cold front brings
the risk of scattered showers and isolated severe thunderstorms
Saturday afternoon and evening, mainly across the interior locations
of southern New England. Showers 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 /THROUGH TONIGHT/...
Key Messages:

* Rain this morning will give way to dry conditions this afternoon.

Frontal boundary continues to move from west to east across southern
New England this morning with periods of moderate rainfall. Cannot
rule out a rumble of thunder as well with marginal instability. Rain
moves out early this morning with clearing skies. Isolated warm
advection showers cannot be ruled out this afternoon 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 sun and clouds. 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, have breezy S to SSW winds 10-15 mph and gusts
up to 25 mph.

Dry tonight, increasing low level moisture along the south coast may
lead to areas of fog/stratus. Mild and muggy overnight, lows fall to
the middle and lower 60s.

&&

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

* Dry to begin, strong to severe storms develop Saturday afternoon
  across southern New England interior.

* Cold front is slow to exit and leads to continued rain showers
  overnight through Sunday morning.

Summer heat and humidly stretches into Saturday with highs returning
to the low to middle 80s! Plus, dew points are into the upper 60s to
perhaps as high as 70F. This helps fuel convective storms during the
afternoon as a mid-level trough and cold front approach, leading to
isolated severe thunderstorms across interior New England. SPC does
highlight the area of greatest risk well with the Day 2 Outlook. If
you are planning to spend the day outdoors, remember to be weather
aware!

Early sunshine will help to warm things up as mentioned, also help
to build instability, with 1,500 J/kg of mean CAPE based off of HREF
with values as high as 2,000 units. The wind field is also looking
more impressive with effective shear 35-45 knots and the effective
SRH 100+ units. SREF shows modest probabilities for severe weather
and the low chance for a tornado for areas of interior southern New
England. The fly in the ointment will be timing of the best forcing,
as the best lift arrives mid to late afternoon. Area of risk is
shown well on the Day 2 Outlook from SPC. Storms are likely to fall
apart as the move east and towards the I-95 corridor. Bit of better
news, feel that the I-95 corridor will remain free of rain for much
of the daylight hours. Tonight there was a discussion whether to
upgrade from a Marginal Risk to a Slight Risk but held off due to
lower confidence. That said, there will be a reevaluation on the day
shift, which could lead to an upgrade in category. Primary hazards
are straight-line damaging wind gusts as the DCAPE values are 900-
1,000 J/kg, hail, heavy downpours and a lower risk, as we like to
say, a non-zero chance for a tornado. With PWATs nearing 1.8" with
isolated area of 2.0" localized flash flooding is possible,
especially for urban locations and areas with poor drainage. WPC
expanded a Marginal ERO into much of southern New England for areas
west of I-95. Timing the convection, reviewing the 00z CAMs storms
could fire in eastern NY/western MA as early as 12-2pm with activity
continuing through the evening hours. Given poor mid-level lapse
rates these storms will likely start to fall apart shortly after
sunset. The cold front is slow to exit and leads to showers
overnight into the start of Sunday.

&&

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

* Feeling cool and raw on Sunday with showers activity through the
  first-half of the day.

* Fall feel returns for next week along with mostly dry weather.

Areas of rain will continue Sunday morning, with showers lingering
the longest on the Cape and Islands. The cold front finally shifts
out to sea with clearing skies Sunday night into Monday. Sunday will
feel much cooler as the region is on the cold side of the front with
temperatures in the lower 70s and upper 60s.

Surface high pressure and rising mid-level heights Monday into the
middle part of next week. Dry fall-like conditions are anticipated
as highs only reach the lower 70s and upper 60s and overnight lows
in the low 50s to upper 40s. Next chance for rain could come late
Wednesday night into Thursday with the passage of a weak low
pressure system.

&&

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

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

18z TAF Update...

Today... High Confidence. Moderate on timing of improvements to
VFR.

IFR cigs scatter out this morning bemusing VFR for the
afternoon. 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-IFR 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. Storms likely develop into a squall line after 19z
and move west. Gusty SSW wind 10-15 knots, gusting 25 knots.


KBOS Terminal...Moderate confidence in TAF.

Likely VFR through the overnight and into tomorrow morning.
Gusty SSW winds, 15-20 knots, gusting to 30 knots. Possible
-SHRA and -TSRA activity after 22z as a line of storms moves
 from west to east.

KBDL Terminal...High confidence in TAF.

Outlook /Sunday through Tuesday/...

Saturday Night: MVFR/IFR conditions possible. Breezy. SHRA
likely, isolated TSRA, patchy BR.

Sunday: Mainly VFR, with local IFR possible. Chance SHRA,
patchy BR.

Sunday Night: VFR. Slight chance SHRA.

Monday through Tuesday: VFR.

&&

.MARINE...
Forecaster Confidence Levels...

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

* A Small Craft Advisory is in effect for all waters beginning
  today and will carry through Saturday evening.

Friday and Saturday... High Confidence.

A few showers are possible overnight into Friday morning and areas
or marine fog. Wind shifts to the SSW for today with sustained winds
of 15-20 knots, with gusts 25-30 knots through Saturday. Seas on the
outer waters are building 4-5 feet and near shore waters are 3-4
feet. A strong cold front will move across the waters late Saturday
into Sunday morning, rain and thunderstorms are possible.

Outlook /Sunday through Tuesday/...

Saturday Night: Winds less than 25 kt. Areas of seas
approaching 5 ft. Chance of rain showers, isolated
thunderstorms, patchy fog. Visibility 1 to 3 nm.

Sunday: Winds less than 25 kt. Areas of seas approaching 5 ft.
Rain showers likely, patchy fog. Visibility 1 to 3 nm.

Sunday Night: Winds less than 25 kt. Areas of seas approaching
5 ft. Chance of rain showers. Local visibility 1 to 3 nm.

Monday: Winds less than 25 kt. Seas locally approaching 5 ft.

Monday Night through Tuesday: Winds less than 25 kt.

&&

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

&&

$$

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