Flood Watch 2, NWS Boston/Norton, MA

Area Forecast Discussion
National Weather Service Boston/Norton MA
715 PM EDT Sat Jul 4 2026

.WHAT HAS CHANGED...
No significant changes with this forecast update.

&&

.KEY MESSAGES...

- Significant heat and humidity continues for the rest of this
  afternoon and evening. Scattered showers and thunderstorms
  possible through the evening. A storm or two may produce
  strong to damaging wind gusts.

- Cooler temperatures are forecast for the first half of the
  week. Temperatures have the potential to be much cooler as a
  soaking rain is becoming more likely in the late Sunday
  through Tuesday time frame.

&&

.DISCUSSION...
KEY MESSAGE 1...Significant heat and humidity continues for the
rest of this afternoon and evening. Scattered showers and
thunderstorms possible through the evening. A storm or two may
produce strong to damaging wind gusts.

Hot and humid conditions ongoing across southern New England,
with temperatures and heat indices alike well into the mid-to-
upper 90s. Heat Advisory in effect for northern CT, majority of
MA, and RI until 8 PM EDT this evening.

Elsewhere, convection is continuing across upstate NY and
central/south VT. This activity is trying to "split the gap"
between southern MA/northern CT/RI and northeastern MA. The
northeastern MA solution is winning at the moment, with a
cluster of storms crossing over into parts of Essex County as of
2:45 PM EDT.

High-resolution guidance has been rather ugly in trying to
picture how the rest of this afternoon and evening unfolds.
Overall, ultimately think that this splits up into two different
"events" (such that they are): this afternoon between now and
5-6 PM, and another between 8-11 PM. Firework shows this evening
could be dicey at times, particularly for eastern MA. Showers
and storms move offshore by 2 AM EDT at the latest.

Cold front due before sunrise Sunday morning, where a wind shift
from the NNE will kick in, veering to the ENE throughout the
day. Highs much more reasonable in the low-to-mid 80s.

KEY MESSAGE 2...Cooler temperatures are forecast for the first
half of the week. Temperatures have the potential to be much
cooler as a soaking rain is becoming more likely in the late
Sunday through Tuesday time frame.

High confidence remains that temps will cool down and return to
more seasonable summer readings thru next week. For starters
850 mb temps are forecast to cool to between +12 to +15C. That
will be enough to get temps back into the 80s on its own.
Dewpoints are also forecast to cool down as well, which will
make things feel more comfortable than it has been.

Temps may also be much cooler if we can get substantial cloud
cover and rain into the forecast area. Overnight guidance has
doubled the number of ensemble members with more than 1 inch of
QPF. Now nearly all of the ECMWF ensemble members are in that
camp around BDL, with roughly half of members greater than 1
inch as you move northeast to BOS. However the GEFS has also
moved on board with roughly half of all members at or above 1
inch QPF across southern New England. Deterministic model
guidance is forecasting mid level warm advection to produce an
area of frontogenesis, giving this a little more synoptic
support for rainfall than the more typical scattered summertime
convective pattern to rainfall. NBM PoP looks pretty good at
this range, with categorical across the southwestern forecast
area and likely farther northeast, given the timing uncertainty.
Rain could begin as early as late Sun night and continue thru
Tue. Right now 6 hr FFG across much of the forecast area is at
least 3 inches, so I am not anticipating flooding unless we see
guidance really start to ramp up QPF numbers.

&&

.AVIATION /00Z SUNDAY THROUGH THURSDAY/...
Forecaster Confidence Levels...

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

00Z TAF Update...

Today through Sunday...High confidence.

VFR conditions dominate through Sunday except during any TSRA.
Storms should move off the northeastern shore by 01-02z, but
moving into western CT/MA 00-02z. Storms should move eastward
off the Cape/Islands by 06Z at the latest tonight. Frontal
passage expected before sunrise Sunday morning, where a wind
shift from the NNE is expected. Winds will continue to veer
towards the ENE throughout the day.

KBOS Terminal...Moderate confidence in TAF. Uncertainty
surrounding thunderstorm coverage and duration.

KBDL Terminal...Moderate confidence in TAF. Uncertainty
surrounding thunderstorm coverage and duration.

Outlook /Monday through Thursday/...

Monday: Mainly VFR, with local IFR possible. Breezy. SHRA
likely, slight chance TSRA.

Monday Night: Mainly MVFR, with local IFR possible. Breezy.
SHRA likely, slight chance TSRA.

Tuesday: Mainly VFR, with local IFR possible. Breezy. SHRA
likely, chance TSRA.

Tuesday Night: Mainly VFR, with local IFR possible. Breezy.
Chance SHRA, slight chance TSRA.

Wednesday: VFR. Slight chance SHRA.

Wednesday Night: VFR.

Thursday: VFR. Breezy.

&&

.MARINE...
Forecaster Confidence Levels...

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

Today through Sunday...High confidence.

A relatively weak pressure gradient will keep winds/seas below small
craft advisory thresholds this holiday Weekend. Some 20+ knot
WNW wind gusts over the land this afternoon may result in some
nearshore chop...but no headlines will be needed for the waters
this weekend with seas generally 3 feet or less.

Outlook /Monday through Thursday/...

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

Monday Night: Winds less than 25 kt. Areas of seas approaching
5 ft. Rain showers likely, slight chance of thunderstorms.

Tuesday: Moderate risk for Small Craft Advisory winds with
gusts up to 25 kt. Seas up to 5 ft. Rain showers likely, chance
of thunderstorms.

Tuesday Night: Winds less than 25 kt. Seas up to 5 ft. Chance
of rain showers, slight chance of thunderstorms.

Wednesday: Winds less than 25 kt. Seas up to 5 ft. Chance of
rain showers.

Wednesday Night: Winds less than 25 kt. Seas up to 5 ft.

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

&&

.BOX WATCHES/WARNINGS/ADVISORIES...
CT...Heat Advisory until 8 PM EDT this evening for CTZ002>004.
MA...Heat Advisory until 8 PM EDT this evening for MAZ002>023-026.
RI...Heat Advisory until 8 PM EDT this evening for RIZ001>007.
MARINE...None.

&&

DISCUSSION...Guest
AVIATION...McMinn/Guest
MARINE...Guest

Preliminary Local Storm Report
National Weather Service Boston/Norton MA
857 PM EDT Sat Jul 4 2026

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0807 PM     Tstm Wnd Dmg     Southington             41.60N 72.88W
07/04/2026                   Hartford           CT   Law Enforcement

            In Southington, multiple trees and wires
            down blocking Andrew St. Relayed via Amateur
            Radio.

0840 PM     Tstm Wnd Dmg     Bristol                 41.68N 72.94W
07/04/2026                   Hartford           CT   Fire Dept/Rescue

            In Bristol, multiple power lines down across
            town. Relayed via Amateur Radio.

&&

Preliminary Local Storm Report
National Weather Service Boston/Norton MA
907 PM EDT Sat Jul 4 2026

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0907 PM     Marine Tstm Wind 4 S South Kingstown     41.37N 71.54W
07/04/2026  M42 MPH          ANZ237             RI   Mesonet

            Mesonet on Matunuck Beach.

&&

Legro

Preliminary Local Storm Report
National Weather Service Boston/Norton MA
932 PM EDT Sat Jul 4 2026

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0840 PM     Tstm Wnd Dmg     Southington             41.60N 72.88W
07/04/2026                   Hartford           CT   Fire Dept/Rescue

            In Southington, multiple trees reported down
            on I-84. Relayed via Amateur Radio.

&&

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