-- Discussion containing changed information from previous version are highlighted. --
487
FXUS61 KBOX 102336
AFDBOX

Area Forecast Discussion
National Weather Service Boston/Norton MA
736 PM EDT Mon Jun 10 2024

.SYNOPSIS...
The weather theme through Tuesday will be mild days and cool nights,
along with an isolated/spot shower during the afternoon. A warming
and drying trend Wednesday and Thursday will lead to increasing heat
and humidity on Friday. An approaching cold front will bring an
increasing risk for showers and thunderstorms Friday, followed by
drier and more seasonable temperatures next weekend.

&&

.NEAR TERM /UNTIL 6 AM TUESDAY MORNING/...
320 PM update...

* Very pleasant/tranquil weather persist into this evening and
  overnight

Gorgeous weather in progress across the region with a mix of sun and
clouds, temps warming into the 70s and very comfortable humidity
with dew pts in the 50s. Diurnal SCU/CU will dissipate with sunset
and give way to a very pleasant evening, with temps falling through
the 70s and into the 60s given the dry airmass in place and
diminishing winds. This will also set the stage for another
seasonably cool night, with lows in the 50s, few upper 40s high
terrain of northwest MA. Given a dry airmass, partly cloudy
conditions and diminishing winds, derived mins overnight from the
cooler MOS guidance.

&&

.SHORT TERM /6 AM TUESDAY MORNING THROUGH TUESDAY NIGHT/...
320 PM update...

Tuesday...

* A cool morning followed by a mild afternoon
* Other than a spot shower, dry weather prevails

Almost a rinse and repeat scenario for tomorrow. Pretty
similar conditions to today, except slightly more cyclonic flow
and colder temps aloft. This will lead to steeper mid level
lapse rates more diurnal clouds than today. Can`t rule out an
isolated, brief, light shower, but otherwise a dry day.
Not much change in low level thermal profiles, with 925 mb temps
around +14C to +15C, which will yield highs in the mid to upper
70s. Cooler along the coast as seabreezes develop in the
afternoon.

Tuesday night...

Diurnal clouds dissipate with sunset given loss of daytime
heating. This will yield mostly clear/partly cloudy conditions
along with light winds, setting the stage for another cool night
with lows in the 50s.

&&

.LONG TERM /WEDNESDAY THROUGH MONDAY/...
320 PM update...

Key Points:

* Early summer warmth Thursday and Friday could affect those most
  sensitive to heat

* Scattered thunderstorms, some possibly strong, late Friday.


Overall no dramatic changes in the forecast from what was offered by
the midnight shift. Some of the details...

Wednesday: a mid level trough and associated cold pool aloft will
swing across the region during the day. Right now the timing
suggested by the models would have this feature offshore by
afternoon. However the cold pool combined with daytime heating
should generate a little bit of instability, albeit rather meager
with CAPE values less than 100 J/kg. We should have rather weak wind
fields in place, so expect sea breeze development. This should be
enough forcing to allow a few showers to develop, especially across
the eastern half of the region. Don`t think shower coverage will be
all that high, so kept PoPs in the 20-30% range for the noon-5pm
timeframe.

Thursday: Southwest winds will bring in a warmer airmass. With 925mb
temperatures in the 18-20C range, this will support highs solidly in
the mid 80s across much of the region (except Cape and Islands).
Winds should be strong enough to keep any sea breeze from moving too
far inland. Dewpoints won`t be too high -- upper 50s to lower 60s,
but this could still give those at risk from hotter temperatures
and/or without air conditioning a few problems

Friday: Still southwest flow across the area, with 925mb
temperatures up a few degrees to the 19-23C range. That would
support high temperatures into the upper 80s, especially inland from
the south coast which will have some cooling effect from the wind
off the water. Dewpoints will also rise a few degrees, so it will
definitely have the mid-summer feel. Of more note is an approaching
cold front and supporting upper level trough. Still uncertainty in
the timing, but it looks like these features would approach the
region late in the afternoon through Friday evening. Models suggest
more robust surface instability than Wednesday (which makes sense
given higher temperatures and dewpoints), with CAPE values over 500
J/kg. Not extreme, but enough to take note. Bulk 0-6km shear is also
40-50kts during the afternoon, suggesting organized convection which
would support strong, if not a few, severe thunderstorms. Timing is
of course a big key as to whether convection lines up best with peak
instability. Right now it looks like timing will be a little on the
late side. Stuck with the NBM 40-50% PoPs, primarily focused on the
5pm to midnight timeframe.

Saturday/Sunday: Ridging and NW flow aloft would point to dry
conditions with near normal temperatures.

Monday and early next week: Some suggestions that we should have a
return to warming conditions and could see several days of
temperatures into the 90s.

&&

.AVIATION /00Z TUESDAY THROUGH SATURDAY/...
-- Changed Discussion --
Forecast Confidence Levels:

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

00Z TAF Update: high forecast confidence through at least Tue
night.

Tonight: VFR cloud bases, dry runways and west wind 10-15 kt
becoming light to calm as the evening and overnight progresses.

Tuesday: rinse and repeat more or less from today. VFR cloud
bases with an isolated, brief, light shower possible in the
afternoon. W wind 5-10 kt with sea-breezes developing along the
coast.

Tuesday night: VFR cloud bases, dry weather and light/variable
winds.

KBOS TAF...High confidence in TAF. Enough WSW wind to hold off
seabreeze today but not Tuesday, when ESE winds develop in the
afternoon. VFR cloud bases and dry weather prevail.

KBDL TAF...High confidence in TAF.

Outlook /Wednesday through Saturday/...

Wednesday: VFR. Slight chance SHRA.

Wednesday Night through Thursday: VFR.

Thursday Night: VFR. Breezy.

Friday: VFR. Breezy. Chance SHRA, isolated TSRA.

Friday Night: Mainly VFR, with local MVFR possible. Breezy.
Chance SHRA, isolated TSRA.

Saturday: VFR.
-- End Changed Discussion --

&&

.MARINE...
Forecaster Confidence Levels:

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

320 PM update...

High confidence through at least Tuesday night.

WSW winds 10-15 kt, gusting up to 20 kt at times, then
diminishing after sunset. Tranquil boating conditions tonight
and Tue with light winds and seas. Winds shift to NW later
tonight behind a weak front, then becoming SE-SW Tue afternoon
as sea- breezes develop. Winds then become light and variable
after sunset Tue evening. Dry weather and good vsby through at
least Tue night.

Outlook /Wednesday through Saturday/...

Wednesday through Thursday: Winds less than 25 kt.

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

Friday: Low risk for Small Craft Advisory winds with gusts up
to 20 kt. Seas up to 5 ft. Slight chance of rain showers,
isolated thunderstorms.

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

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

&&

.BOX WATCHES/WARNINGS/ADVISORIES...
CT...None.
MA...None.
RI...None.
MARINE...None.

&&

$$

SYNOPSIS...Nocera/Nash
NEAR TERM...Nocera
SHORT TERM...Nocera
LONG TERM...Nash
AVIATION...Nocera/Dooley/Nash
MARINE...Nocera/Nash