604
FXUS61 KBOX 111852
AFDBOX

Area Forecast Discussion
National Weather Service Boston/Norton MA
252 PM EDT Mon Aug 11 2025

.SYNOPSIS...
Heat and humidity on the rise this week, peaking on Wednesday,
but not as oppressive as it was earlier in the summer. Scattered
showers and thunderstorms are expected ahead of a cold front
later Wednesday and Thursday, then dry and cooler weather
follows Friday into the weekend, but heat could return Sunday.

&&

.NEAR TERM /UNTIL 6 AM TUESDAY MORNING/...
Key Message:

* Hot and humid today with clear skies.

High pressure building south of our waters is providing
southwesterly flow (with the exception of sea breezes along the
coasts)... bringing hot and humid air over southern New England.
This afternoon`s temperatures will peak in the low 90s for most
areas... upper 80s for the South Coast, Cape and Islands.

Another mainly clear night ahead with patchy fog possible near
Cape Cod/Islands and perhaps inland as well. Given the clear
skies and low winds, expecting some radiational cooling tonight
allowing the CT River Valley and Merrimack Valley to drop into
the low 60s.

&&

.SHORT TERM /6 AM TUESDAY MORNING THROUGH TUESDAY NIGHT/...
Key Messages:

* Heat and humidity continue to rise Tuesday, but still short of
  a Heat Advisory.

While heat and humidity continue to rise through midweek,
forecast soundings on Tuesday indicate fairly deep mixing...
bringing down drier air from aloft and lowering afternoon
dewpoints into upper 50s and lower 60s. This will reduce the
apparent temperatures Tuesday afternoon. While we`ll come close
to Heat Advisory criteria (heat index of 95-100F for 2 or more
hours) still thinking we`ll fall short of the 2 consecutive day
threshold. Regardless, it will be hot and humid, although not to
extent as what we experienced earlier in the summer.

&&

.LONG TERM /WEDNESDAY THROUGH MONDAY/...
Key Messages:

* Warm/humid with elevated heat indices Wed, but cold front brings a
  risk for t-storms Wed late-day into early Thurs.

* Cooler with lower humidity levels Fri/Sat with drier weather.

* Warming trend with rising humidity levels Sun.

Details:

Most active portion of this period is on Wed, with another day of
very warm to hot temperatures and some humidity leading to elevated
heat indices. With strong heating likely to permit mixing of drier
air aloft, still think modeled dewpoints (mid 70s) from the NBM are
running a bit high and ended up undercutting these by a few degrees,
which keeps heat indices in the mid to mid/upper 90s. A cold front
will also be arriving later in the day which will bring with it the
risk for thunderstorms given the warmth and humidity; however the
front`s timing looks offset from peak heating which could limit the
potency of any storms. The front won`t clear our area until Thurs,
which could bring additional showers or thunderstorms to eastern
MA/RI.

We then return to drier weather Fri through the weekend. Cooler
temperatures along with much lower levels of humidity are then
expected for Fri into Sat. However southwest flow returns on
Sun, which will bring a warming trend to temperatures along with
rising humidity levels.


&&

.AVIATION /19Z MONDAY THROUGH SATURDAY/...
Forecaster Confidence Levels...

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

18z TAF Update: High confidence.

VFR. Light S/SW winds with sea breezes along both coasts today
and Tue.

KBOS terminal...High confidence in TAF.

KBDL terminal...High confidence in TAF.

Outlook /Wednesday through Saturday/...

Wednesday: VFR. Breezy. Slight chance SHRA, slight chance TSRA.

Wednesday Night: VFR. Breezy. Chance SHRA, slight chance TSRA.

Thursday: VFR. Chance SHRA, slight chance TSRA.

Thursday Night: VFR. Slight chance SHRA.

Friday through Saturday: VFR.

&&

.MARINE...
Forecaster Confidence Levels...

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

High confidence through the period.

Weak gradient will allow for sea breezes near shore today and
Tue before high pressure offshore brings increasing SW flow
thereafter, though winds and seas should remain below SCA
levels. Patchy fog may limit visibility later at night and early
in morning for much of this week.

Outlook /Wednesday through Saturday/...

Wednesday: Winds less than 25 kt.

Wednesday Night: Winds less than 25 kt. Seas locally
approaching 5 ft. Chance of rain showers, slight chance of
thunderstorms.

Thursday: Winds less than 25 kt. Chance of rain showers.

Thursday Night: Winds less than 25 kt. Slight chance of rain
showers.

Friday through Saturday: Winds less than 25 kt.

&&

.BOX WATCHES/WARNINGS/ADVISORIES...
CT...Air Quality Alert until 11 PM EDT this evening for CTZ002>004.
MA...Air Quality Alert until 11 PM EDT this evening for MAZ004>016-
     026.
RI...None.
MARINE...None.

&&

$$

SYNOPSIS...Loconto/McMinn
NEAR TERM...McMinn
SHORT TERM...McMinn
LONG TERM...Loconto
AVIATION...Loconto/McMinn
MARINE...Loconto/McMinn