496
FXUS61 KBOX 041815
AFDBOX

Area Forecast Discussion
National Weather Service Boston/Norton MA
215 PM EDT Fri Jul 4 2025

.SYNOPSIS...
Tranquil weather with low humidity is expected tonight and
continues into Saturday. Very warm temperatures in the upper 80s
to lower 90s and rising humidity levels will lead to high heat
indices Sunday and Monday. Unsettled weather may make a return
Monday night through much of the week, but timing remains
uncertain.

&&

.NEAR TERM /THROUGH TONIGHT/...
200 PM Update:

Key Messages:

* Easing northwest breezes early, with clear skies with low
  humidity tonight.

* Possible early-morning patchy radiation fog in NW MA, CT
  Valley and around I-495 in MA.

It`s been a beautiful Independence Day with seasonably warm
temperatures and very low perceived humidity (dewpoints as low
as the mid 40s!). It is rather breezy with NW gusts around 25
mph, but those will subside shortly after sundown.

Dry weather remains expected for the balance of the evening and
overnight, and with a decreasing NW wind, should be ideal for
any outdoor/holiday activities. Good radiational cooling is
expected tonight with inversion developing around midnight. This
could increase the risk for patchy radiation fog in the typical
areas (NW MA, CT River Valley, around/in vicinity of I-495 in
MA), especially in light of sfc moisture fluxes from recent
rainfall. Temps from sundown to midnight in the mid 60s to
around 70, and used MOS for lows in the mid 50s to lower 60s.

&&

.SHORT TERM /SATURDAY THROUGH SATURDAY NIGHT/...
200 PM Update:

Key Messages:

* Mostly sunny and dry on Sat, possible coastal seabreezes.
  Highs mid 80s.

* Warmer lows and turning a little more humid Sat night.

High pressure in interior Southern New England early on Sat then
slides southward into the southern offshore waters, amid a
regime of rising 500 mb heights. Dry weather remains expected
for Saturday with mostly sunny skies; although a little bit
warmer than today with highs in the mid 80s, humidity levels
should still prove tolerable. One aspect of the forecast to
watch is a possible coastal seabreeze as boundary layer winds
fall to around or just lower than 10 kt. That could keep the
immediate coastal areas a little cooler but it`s not certain if
the seabreeze will materialize or if it lies just offshore.

Although we`re looking at drier weather again for Sat evening,
midlevel warm front works its way across Southern New England.
This will bring a modest increase in mid to high clouds, but
also lead to warmer nighttime lows and dewpoints in the lower
60s, which is a bit more humid.

&&

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

* Hot and humid for Sunday and Monday (especially Monday)

* Heat Advisory in effect Sunday morning through Monday for much of
  southern New England, excluding the Berkshires and south coast
  into Cape Cod and the Islands

* Unsettled weather returns starting Monday night into Tuesday

Details...

A ridge builds up along the east coast Sunday. SW flow dominates
into Monday, advecting in warm and moist air for most. Due to the
expected heat and humidity from this pattern, a Heat Advisory is in
effect from Sunday morning through Monday. Heat indices of 95-100F
are expected across much of southern New England, except for the
Berkshires and the south coast into the Cape and Islands. The south
coast will be slightly cooler than the rest of the region due to the
cooler air from over the ocean flowing over these areas. However, it
will still be humid; dew points will reach the low to mid 70s across
the region Monday, with the higher values towards the south coast.
Highs there will likely remain mostly in the low 80s Sunday and
Monday, while the rest of the region can expect highs up into the
low to mid 90s.

A cold front moves across the region Tuesday, and flow becomes more
zonal. Rain chances make a return ahead of this front Monday night
and increase during the day Tuesday. Generally, much of the week
from this point on looks unsettled as a trough digs into the Great
Lakes region and a series of shortwaves progress east along its
base. Although, a brief break looks possible for Wednesday before
the next chances for rain arrive for Thursday into Friday. More
exact timing and location details are still uncertain at this time.

&&

.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:

Through Tonight: High confidence, lower on radiation fog
potential.

VFR, with decreasing NW gusts from 20-25 kt by sundown, with
decreasing NW winds less than 5 kt overnight. Recent rainfall
and good radiational cooling could favor patchy fog 07-11z at
BAF, BED and possibly BDL.

Saturday and Saturday Night: High confidence.

VFR. Winds to become SWly around 5-10 kt, but will have to watch
for possible seabreezes at BOS and PVD as BL winds are on the
lighter side (~10 kt). Light SW winds expected Sat night.

KBOS Terminal...High confidence in TAF. VFR, NW gusts to 25 kt
decrease after sundown. Possible seabreeze Sat around 16-17z?

KBDL Terminal...High confidence in TAF. VFR, decreasing NW gusts
after sundown.

Outlook /Sunday through Tuesday/...

Saturday Night: VFR.

Sunday through Sunday Night: VFR. Breezy.

Monday: VFR. Breezy. Slight chance SHRA.

Monday Night: VFR. Slight chance SHRA, slight chance TSRA.

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

&&

.MARINE...
Forecaster Confidence Levels...

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

Through Saturday Night: High confidence.

Tranquil boating weather conditions through Saturday evening. NW
gusts around 15-20 kt through this afternoon, which then
decrease to 10 kt or less overnight. SW winds around 10-15 kt on
Sat and Sat night. Seas 4 ft or less all waters, and around 1-2
ft nearshore. No obstructions to visibility expected.

Outlook /Sunday through Tuesday/...

Saturday Night: Winds less than 25 kt.

Sunday through Sunday Night: Winds less than 25 kt. Seas
locally approaching 5 ft.

Monday: Winds less than 25 kt.

Monday Night: Winds less than 25 kt. Chance of rain showers,
slight chance of thunderstorms.

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

&&

.BOX WATCHES/WARNINGS/ADVISORIES...
CT...Heat Advisory from 7 AM Sunday to 8 PM EDT Monday for
     CTZ002>004.
MA...Heat Advisory from 7 AM Sunday to 8 PM EDT Monday for
     MAZ003>007-010>019-026.
RI...Heat Advisory from 7 AM Sunday to 8 PM EDT Monday for
     RIZ001>004.
MARINE...None.

&&

$$

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