918
FXUS61 KBOX 052324
AFDBOX

Area Forecast Discussion
National Weather Service Boston/Norton MA
724 PM EDT Fri Jun 5 2026

.WHAT HAS CHANGED...
The Level 2 of 5 (Slight Risk) for severe weather for Saturday
late-afternoon to evening has been adjusted eastward into
eastern Massachusetts for localized straight-line wind damage.
Additional storms are expected starting early Sunday afternoon
as well, but these storms should be in the sub-severe range.
Finally, small craft advisories have been posted for the
southern waters for Saturday.

&&

.KEY MESSAGES...

- Warm temperatures this weekend, with scattered thunderstorms
  (some strong to severe) late in the day into the evening
  Saturday. Another round of afternoon showers and thunderstorms
  in greater coverage is expected Sunday, mainly into
  central/eastern MA and RI.

- Cooler start to the workweek gives way to a warming trend
  with summer-like warmth mid to late week.

&&

.DISCUSSION...
KEY MESSAGE 1...Warm temperatures this weekend, with scattered
thunderstorms (some strong to severe) late in the day into the
evening Saturday. Another round of afternoon showers and
thunderstorms in greater coverage is expected Sunday, mainly into
central/eastern MA and RI.

For Saturday...we`ll still be awaiting the arrival of an initial
cold front which will be working its way into northwestern MA later
in the day. Until then, very warm to hot temperatures are expected
Saturday under full sunshine, reaching into the mid 80s to low 90s
with a touch of humidity, but not oppressive or enough to raise heat
indices to the point of needing heat headlines. The approach of the
cold front will be moving into an environment characterized by
moderate instability (CAPEs on the order of 1000-1500 J/kg north and
west of I-95) and a well-mixed atmosphere favoring strong downdrafts
with progged downdraft CAPE values around 700-900 J/kg. There is
also some steeper mid-level lapse rates around 6.5-7 C/km, which
linger well into the evening hours. Often with mid-level lapse rates
at that level, it can sustain thunderstorms even into the evening
hours. Wind fields aloft increase some but are not necessarily eye-
popping, with 0-6 km shear values around 30-40 kt. The cold front`s
late timing and that moisture levels are sub-par are main limiting
factors to a more organized severe weather threat. We`ll probably be
waiting for storms to develop and/or move east into western New
England until 5-8 PM, and then slowly evolve into a broken line
of storms moving ESE through interior Southern New England to
the I-95 corridor between 8 pm to midnight, then moving offshore
shortly after midnight for the coasts. A Slight Risk (Level 2
of 5) for severe weather has been expanded eastward from central
MA/CT and on into the eastern MA metro areas, and the main
severe weather risk is for straight-line wind damage and gusty
outflow/"microburst" winds which could down trees and
powerlines. Thinking the window for storms to become severe is
in the 6-9 PM timeframe, then as conditions stabilize, we should
see a continued risk for thunderstorms as they move offshore
but could still be capable of heavy downpours, lightning and
sub- severe wind gusts. Of the two weekend days, it`s late
Saturday and into early Saturday night that harbors the greatest
potential for storms to produce severe weather. The front moves
offshore overnight, and with it brings at least a brief period
of drier conditions which continues into Sunday morning.

For Sunday...we`ll start off with drier conditions during the
morning hours as temperatures start to warm into the lower to mid
80s with some humidity. We then await a stronger mid-upper level
disturbance aloft with a cool pocket of air aloft, which will be
digging southward during the early afternoon hours into NH. There
should be enough instability around to go along with increasing
mid/upper level support from the disturbance aloft and weak
inhibition to generate showers and thunderstorms in scattered to
even numerous coverage by early afternoon (as soon as noon), then
building southeast toward the southern coast thru late
afternoon. Instability values look less compared to Saturday,
which should temper the severe threat, but storms could still be
capable of small hail with the cooler air aloft and localized
gusty winds. With not much to force storms other than the
disturbance aloft, we couldn`t say no to a storm occurring
virtually anywhere, but the greatest risk looks to be centered
from a Fitchburg- Worcester-Willimantic line eastward to the
eastern/southern coast, and a lesser risk westward into the CT
Valley/Berkshires. In sum, Sunday could offer a greater
thunderstorm coverage than Saturday, but the chances any
individual storm reaches severe limits is lower.

KEY MESSAGE 2...Cooler start to the workweek gives way to a
warming trend with summer-like warmth for the mid to late week.

The workweek starts on a cooler note as northerly flow behind a
departing trough keeps cooler temperatures aloft. At the surface,
onshore flow keeps temps in the 70s at the coast. Further inland,
temps warm into the low 80s away from the marine influence. The
column quickly warms Tuesday and stays that way through middle of
next week as an expansive upper-level ridge builds over the central
CONUS. Aloft, 850 mb temperatures soar to +15-18C. Unsurprisingly,
dry conditions are likely through much of next week as surface high
pressure builds overhead. Bigger story will be the increasing heat
starting Tuesday through much of the upcoming week. Ensemble
guidance shows somewhat impressively high probabilities for high
temps >90F with values between 50 and 60% in the CT and Merrimack
River Valleys Tues-Fri.

&&

.AVIATION /00Z SATURDAY THROUGH WEDNESDAY/...
Forecaster Confidence Levels...

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

00z TAF Update:

Tonight: High confidence.

VFR. Winds tonight turn light SW for interior terminals with
ENE winds for NE MA/BOS.


Saturday: High confidence.

VFR for most of the time, although the risk for isolated to
scattered thunderstorms increases after 21z from ORH westward.
Some storms could turn strong with gusty winds leading to local
turbulence being the main risk. A greater storm coverage is more
likely after 00z eastward. Winds become SW and increase to
around 10-12 kt with gusts 20-25 kt.

Saturday Night: Moderate confidence.

VFR outside of scattered thunderstorms which could bring local
IFR visby restrictions. Initial widely scattered storms should
turn into a broken line of storms moving eastward into the
ORH-BED-BOS-PVD corridor between 00-03z, then move offshore. A
couple storms could still be strong early with localized gusty
winds, but general weakening trends are more likely. Brief
clearing between 04-08z north to south as front moves offshore.
SW winds around 10 kt then shift to W/WNW 5-10 kt.

Sunday: High confidence in trends but moderate on timing.

VFR initially, though SHRA/TS develops as soon as 16z Sunday in
the MA/VT/NH border area and progresses south/southeast.
SHRA/TS could be greater in coverage compared to Saturday, with
best chances from ORH eastward to the Cape and Islands (lesser
chance/coverage west), and a couple could be strong. Thinking
decreased coverage after 21z Sunday. Winds become NW around
10-13 kt, with winds coming NE late in the day.

KBOS...High confidence in TAF but moderate on timing of wind
directions. VFR through 00z Sunday. ENE winds overnight tonight
before turning SW around 16-17z Sat.

KBDL...High confidence in TAF. VFR, with SW winds overnight. TS
possible after 22z Saturday.

Outlook /Saturday Night through Wednesday/...

Sunday: VFR. Breezy. Chance SHRA, slight chance TSRA.

Sunday Night: VFR. Breezy. Slight chance SHRA.

Monday: VFR. Breezy.

Monday Night through Tuesday Night: VFR.

Wednesday: VFR. Breezy.

&&

.MARINE...
Forecaster Confidence Levels...

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

Through Sunday Night: High confidence.

Small Craft Advisories have been posted for Saturday afternoon
into Saturday night for the southern waters as the combination
of SW winds gusts to 25 kt and building seas to around 4-6 ft.
A risk for thunderstorms capable of lightning, heavy downpours
and localized strong wind gusts too mainly after 7 PM on both
southern and eastern waters.

Another round of scattered showers and thunderstorms develops
Sunday afternoon. There could be a period Sunday late afternoon
and evening where the eastern waters could see northerly to
northeast wind gusts to 25 kt, which could prompt the need for
small craft advisories on most if not all waters.

Outlook /Saturday Night through Wednesday/...

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

Sunday Night: Low risk for Small Craft Advisory winds with
gusts up to 25 kt. Areas of rough seas. Slight chance of rain
showers.

Monday: Low risk for Small Craft Advisory winds with gusts up
to 25 kt. Areas of rough seas.

Monday Night: Winds less than 25 kt. Areas of seas approaching
5 ft.

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

Tuesday Night through Wednesday: Winds less than 25 kt.

&&

.BOX WATCHES/WARNINGS/ADVISORIES...
CT...None.
MA...None.
RI...None.
MARINE...Small Craft Advisory from 2 PM Saturday to 8 AM EDT Sunday for
     ANZ232>235-237-254>256.

&&

$$

DISCUSSION...Loconto/FT
AVIATION...Loconto/FT
MARINE...Loconto/FT