803
FXUS61 KBOX 111718
AFDBOX

Area Forecast Discussion
National Weather Service Boston/Norton MA
118 PM EDT Thu Jul 11 2024

.SYNOPSIS...
A few showers into mid morning will be followed by plenty of
sunshine with hot and somewhat humid weather today. Much of
Friday will feature dry weather but a few showers will be
possible during the afternoon. A frontal boundary dropping
south will bring showers and embedded thunderstorms to the
region sometime Friday night into Saturday with localized
torrential rainfall possible. Dry weather returns by
Sunday...but it will be hot and humid. The heat and humidity
will continue through the middle of next week which will require
the need for additional Heat Headlines. There also may be a
round or two of scattered showers/thunderstorms in the Monday
through Wednesday period...but timing remains uncertain.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
10am Update

Lingering low cloud cover and drizzle should come to an end by
the lunch hour as the front slowly moves offshore. Already
starting to see clearing across western MA and CT. The clearing
line should make it all the way into eastern MA and RI this
afternoon, with the Cape and Islands stuck in cloud cover as the
front stalls nearby.

Today

A weak frontal boundary pushes through southern New England this
morning with a few showers and perhaps a rumble of thunder before
stalling out offshore. Expect substantial clearing across interior
southern New England by late morning/early afternoon. Gusty
southwest winds from yesterday will persist into today as well with
a relatively impressive low-level jet for mid-July overhead. Mixing
of drier air aloft to the surface will support dewpoints falling
into the upper 60s across most of interior southern New England this
afternoon. This will support a slight improvement to the oppressive
heat and humidity that has been observed the last few days.
Dewpoints will take longer to fall across eastern MA and RI where
low do mid 70s dewpoints will persist into the early to mid-
afternoon. Lingering cloud cover across southeast MA and RI should
prevent heat indices from reaching advisory criteria, but heat
indices close to 90 are likely for these areas this afternoon.
Across northeast MA, there should be enough sunshine to support
surface temps near 90 which may allow for an additional day with a
95+ heat index. Thus, a heat advisory remains in effect for Essex
County through this evening. Overall a relatively quiet day, but it
is worth nothing that southwest wind gusts may gust to 30+ mph at
times this afternoon. Strongest winds look to be across southeastern
MA and The Cape.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM FRIDAY/...
Tonight

Quiet and relatively cooler tonight with many locations experiencing
sub-70 degree low temperatures for this first time in several
nights. Temps remain a big muggy across eastern MA an RI with lows
in the low 70s. A few showers and possibly a rumble of thunder
possible along the south coast with a stationary front just offshore.
Expect most locations to stay dry. Gusty southwest winds gradually
diminish overnight.

Tomorrow

No big change to the air mass in place over southern New England
tomorrow. Heat indices in the 90s once again with some unsettled
weather possible along a lingering stationary front. Overall forcing
looks week so not expecting a washout, but a few isolated to
scattered afternoon showers/storms will be in the cards again.
Modest southwest winds from 10 to 15 mph.

&&

.LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/...
Key Points...

* Humid with Showers & embedded t-storms Fri night into Sat with
  pockets of torrential rainfall & localized flash flooding possible

* Hot & Humid Sun through Wed of next week & Heat Headlines expected

* Potential for a round or two of scattered showers & t-storms in
  the Mon through Wed time frame...but dry weather much of the time

Details...

Friday night and Saturday...

Shortwave energy will lift northward into our region as a mid level
trough axis approaches from the west Fri night into Sat. This will
allow very humid air to return to the region with dewpoints in the
lower to middle 70s and Pwats of 2+ inches. As a surface front
begins to drop southward into this region...the forcing for ascent
will increase and allow for showers and embedded t-storms to develop
sometime Fri night into Sat. Timing still needs to be worked out and
the amount of low level forcing is uncertain. What evolves will
highly depend on mesoscale features that can not be assessed at this
time. Nonetheless...given Pwats over 2 inches and a boundary in the
region...pockets of torrential rainfall and the risk for localized
flash flooding will need to be monitored.

Saturday night and Sunday...

Shortwave energy/frontal boundary pushes east of the region later
Sat or Sat night. Drier weather will work in from the west and will
result in a generally dry but hot & humid weather on Sunday. Highs
will probably be back in the upper 80s to the lower 90s in most
locations and we may reach Heat Advisory criteria in some locations.

Mon/Tue/Wed...

Hot and humid weather looks to continue Mon/Tue/Wed of next week.
GEFS/EPS/CMC guidance continues to indicate 2 meter temp/500 mb
height fields above normal. Highs should mainly be in the upper 80s
to the lower 90s with even some middle 90s possible at times...at
least away from areas of the immediate coast/localized marine
influences. Heat Headlines will likely be needed for much of this
time too. Afternoon Heat Indices may be in the 95 to 100 degree
range.

The other concern will be the potential for a round of two of
scattered showers and t-storms in the Mon through Wed time frame.
Now much of this period will feature dry weather and shortwave
energy is impossible to time this far out. We may have some sort of
remnant EML around...so if we do have strong enough wind fields the
risk for severe weather would exist. While it is too early to
assess...the CSU Machine learning probs do indicate some modest
severe probs in the Day 5-7 time period. So something will need to
watch in the coming days.

&&

.AVIATION /18Z THURSDAY THROUGH MONDAY/...
Forecast Confidence Levels:

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

Rest of Today...High confidence.

VFR with pockets of MVFR across the interior. The Cape and
Islands will remain IFR with periods of drizzle. Winds remain
gusty out of the SSW at 20-25 knots inland, and 25-30 knots
near the coasts.

Tonight...High Confidence.

VFR for interior terminals with MVFR/IFR along the south coast,
and IFR/LIFR for the Cape and Islands. Periods of drizzle and
showers possible across the Cape and Islands.

Friday...Moderate Confidence

VFR with the exception for the Cape and Islands once again could
still be stuck in MVFR/IFR. Low chance for isolated showers and
thunderstorms in the afternoon.

Friday Night...Low Confidence

MVFR with localized IFR possible. Widespread rain and
thunderstorm chances increase towards morning.

KBOS TAF...Moderate confidence in TAF.

VFR today with gusty SSW winds up to 25 knots. Winds remain SSW
but gradually decrease this evening, but become gusty again
tomorrow afternoon up to 20 knots. Low chance for a shower or
thunderstorm tomorrow afternoon

KBDL TAF...Moderate confidence in TAF.

VFR today and tonight with gusty SSW winds. Winds diminsh
tonight but could become gusty again tomorrow afternoon. Low
chance for a shower or thunderstorm tomorrow afternoon.

Outlook /Friday Night through Monday/...

Friday Night through Saturday: Mainly MVFR, with local IFR
possible. Breezy. Chance SHRA, slight chance TSRA.

Saturday Night: Mainly VFR, with local MVFR possible.

Sunday through Sunday Night: VFR.

Monday: Mainly VFR, with areas MVFR possible. Breezy. Chance
SHRA, chance TSRA.

&&

.MARINE...
Forecaster Confidence Levels:

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

Marine

Today through Tomorrow

Small craft advisories in effect for most of the coastal waters
today with gusty southwest winds up to 30 knots possible. Seas rise
to 5 to 7 feet over the south coastal waters in response to
strengthening southwest winds. Winds gradually diminish to more
modest levels overnight with peak gusts below 20 knots. Seas
gradually subside to 5 feet or less by Friday afternoon.


Outlook /Friday Night through Monday/...

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

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

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

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

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

&&

.BOX WATCHES/WARNINGS/ADVISORIES...
CT...None.
MA...Heat Advisory until 8 PM EDT this evening for MAZ005>007.
     High Surf Advisory until 8 PM EDT this evening for MAZ020-
     022>024.
RI...High Surf Advisory until 8 PM EDT this evening for RIZ006>008.
MARINE...Small Craft Advisory until 8 PM EDT this evening for ANZ230-
     231-236-251.
     Small Craft Advisory until 8 AM EDT Friday for ANZ232>235-237-
     250.
     Small Craft Advisory until 9 PM EDT Friday for ANZ254>256.

&&

$$

SYNOPSIS...Frank/RM
NEAR TERM...RM/KP
SHORT TERM...RM
LONG TERM...Frank
AVIATION...KP
MARINE...Frank/RM