316
FXUS61 KBOX 240852
AFDBOX

Area Forecast Discussion
National Weather Service Boston/Norton MA
452 AM EDT Tue Jun 24 2025

.SYNOPSIS...
Dangerous heat and humidity peaks today, though Wednesday is less
hot, it is still very warm and humid. Scattered thunderstorms are
possible Wednesday afternoon as a cold front moves from north to
south across the region. Finally turning cooler Thursday through the
upcoming weekend with daily chances of showers and
thunderstorms.

&&

.NEAR TERM /THROUGH TONIGHT/...
330 AM UPDATE

Key Messages:

* Dangerous heat and unhealthy air quality continues Tuesday.

* Will challenge warmest June day record at the four climate sites.

A warm and muggy morning across southern New England with many spots
in the 70s early this morning. Patchy radiational fog developed in
spots, but do expect that and any patchy coastal stratus to erode
during the morning.

This afternoon will be the warmest thus far, 00z guidance shows a
vast mid-level ridge across the eastern CONUS and the temperatures
at 925mb over southern New England are +28C to +30C! Incredible heat
and resulting temperatures are in the upper 90s to lower 100s. Areas
along coast of Rhode Island and south coastal Massachusetts are in
the lower to middle 90s, while the "least hot" locations are the
islands, which are in the 80s. A breezy west/northwest wind provides
a bit of downsloping and will be able to mix out some "drier" dew
points around 68F to 72F. Still, the combination of the record heat
and dew points will lead it to feel like 100F to 110F for much of
the region. NWS HeatRisk places majority of the region under a major
risk and urban locations under an extreme risk. Anyone spending any
amount of time outdoors today needs to be self aware of heat-related
illnesses. Also, check in on those family and friends who may not
have access to a place to cool off.

Beyond daily records will be challenged today, each of the climate
sites (BOS, ORH, PVD, BDL), will challenge the warmest June day on
record.

* BOS: 100F set in 2021, 1952, and 1925
* ORH: 98F set in 1952
* PVD: 98F set in 1945 & 1943
* BDL: 100F set in 1964 & 1952

There are no changes to ongoing Extreme Heat Warning & Heat Advisory
these remain in effect through this afternoon. As well, an Air
Quality Alert is in effect through 11pm in collaboration with
Massachusetts Department of Environmental Protection and Rhode
Island Department of Environmental Management for ground level ozone
concentrations to approach or exceed unhealthy standards.

Heading into the late afternoon a few showers may try to develop
mainly across northern New England, a rouge shower cannot be ruled
out for extreme northern Massachusetts. As for overnight relief, no
such luck, overnight lows hover in the middle to upper 70s, slightly
less warm at the south coast in the lower 70s.

&&

.SHORT TERM /WEDNESDAY THROUGH WEDNESDAY NIGHT/...
330 AM UPDATE

Key Messages:

* Less hot for Wednesday, though feels like temperatures are still
  95F to 100F.

* Scattered thunderstorms possible Wednesday afternoon, though not
  every town of city sees one.

Another hot and humid day is on tap for Wednesday, but not expected
to be a severe as Tuesday. 925mb temperatures are decreasing and are
settled around +22C to +24C, yields highs in the upper 80s to middle
90s. Though, with the higher dew points, which increase to the lower
70s, heat index during the early to mid-afternoon are 95F to 100F,
and likely need a Heat Advisory as a result. Expecting the day crew
to reassess and issue during the afternoon forecast package. The
cold front will bring the chance of hit-or-miss thunderstorms, which
have the potential to become strong or borderline severe. SPC does
have southern New England under a Marginal Risk (level 1 of 4) for
severe weather. After reviewing the 00z CAMs have opt`d to bump the
POPs up from the previous forecast, between 35% and 45%. If those
storms fire up earlier this could result in lower than expected high
temperatures.

Overnight will have clouds and spotty showers in the vicinity of the
stalled cold front, out over the southern waters. Best chance for
any showers overnight will be the immediate south coast of Rhode
Island and Massachusetts, which includes the Cape and Islands. Look
for overnight temperatures in the middle to upper 60s.

&&

.LONG TERM /THURSDAY THROUGH MONDAY/...
330 AM UPDATE

Key Messages:

* Cooling trend Thursday through Saturday, slightly warmer by late
  weekend.

* Daily chances of rain and/or thunderstorms Thursday through the
  weekend as well.

Much needed relief from the heat comes on Thursday as high pressure
moves off the coast of eastern Canada, bringing northeast flow off
the North Atlantic Ocean. This set up last Thursday and Friday with
highs in the 70s. Will see a slow rise in temperatures Saturday to
the mid 70s and the 80s on Sunday. Cold front to our south will
become quasi-stationary, becoming a source area for shower activity
Thursday into the upcoming weekend. Though, no significant systems
or washouts are on the horizon.

&&

.AVIATION /09Z TUESDAY THROUGH SATURDAY/...
Forecaster Confidence Levels...

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

Through 12z: High Confidence. Moderate Confidence (ceilings at ACK)

Mainly VFR. Patchy BR/FG possible again along the South Coast, with
better chance for the Cape airports. ACK could see a period of lower
ceilings overnight as a SCT-BKN deck tries to push in, but
confidence is currently low to moderate. Light west winds,
increasing in speed toward morning to around 5-10 kt.

Today: High Confidence.

Any BR/FG from overnight disperses shortly after sunrise with VFR
thereafter. W winds increase to around 8-12 kt with gusts to 20 kt.

Tonight: High confidence.

VFR. W winds around 10 kts with gusts up to 20 kts possible across
the interior terminals.

Wednesday and Wednesday Night: Moderate Confidence.

VFR. Scattered early to mid afternoon showers and thunderstorms. A
few showers linger across the islands and Cape Cod overnight. Light
and variable winds depending on placement of the cold front. Becoming
northeast Wednesday night.

KBOS Terminal...High confidence in TAF. Some gusts up to 20 kts
possible tomorrow afternoon.

KBDL Terminal...High confidence in TAF. VFR. Hazy conditions
possible given hot and humid weather.

Outlook /Thursday through Saturday/...

Thursday: Mainly VFR, with local MVFR possible. Breezy. Chance
SHRA.

Thursday Night: Mainly VFR, with local MVFR possible. Slight
chance SHRA.

Friday: Mainly VFR, with areas MVFR possible. Slight chance
SHRA.

Friday Night: Mainly VFR, with local IFR possible. Chance SHRA.

Saturday: MVFR/IFR conditions possible. Breezy. Chance SHRA,
slight chance TSRA.

&&

.MARINE...
Forecaster Confidence Levels...

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

Today through Wednesday: High Confidence.

Tuesday begins with areas of low clouds and fog, but erodes during
the mid-morning hours, otherwise, mainly clear skies on Tuesday. A
southwest wind of 10 to 15 knots will be accompanied by gusts up to
20 knots. Where gusts could be locally stronger are the southern
waters from Block Island Sound to Nantucket sounds, it is here where
gusts could approach 25 knots. Seas remain less than 2 feet. These
conditions are sub-criteria for a Small Craft Advisory, but boaters
should be aware of infrequent gusts to near advisory criteria.

Weak cold front approaches from the north on Wednesday, increasing
clouds and a few pop-up showers and thunderstorms. Northern waters
have northerly winds while the southerly waters have a southerly
wind. Wind becomes northeast for all waters Wednesday night and
increase to 10 to 15 knots. Seas are less than 2 feet.

Outlook /Thursday through Saturday/...

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

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

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

Friday Night: Winds less than 25 kt. Seas locally approaching
5 ft. Chance of rain showers.

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

&&

.BOX WATCHES/WARNINGS/ADVISORIES...
CT...Extreme Heat Warning until 8 PM EDT this evening for
     CTZ002>004.
MA...Extreme Heat Warning until 8 PM EDT this evening for
     MAZ003>007-010>021-026.
     Heat Advisory until 8 PM EDT this evening for MAZ002-008-009.
     Air Quality Alert from 11 AM this morning to 11 PM EDT this
     evening for MAZ017>024.
     Heat Advisory from 10 AM this morning to 8 PM EDT this evening
     for MAZ022.
RI...Extreme Heat Warning until 8 PM EDT this evening for
     RIZ001>007.
     Air Quality Alert from 11 AM this morning to 11 PM EDT this
     evening for RIZ001>008.
MARINE...None.

&&

$$

SYNOPSIS...Dooley
NEAR TERM...Dooley
SHORT TERM...Dooley
LONG TERM...Dooley
AVIATION...Dooley
MARINE...Dooley