057
FXUS61 KBOX 101723
AFDBOX

Area Forecast Discussion
National Weather Service Boston/Norton MA
123 PM EDT Wed Jul 10 2024

.SYNOPSIS...
Heat and humidity continues today with a few showers and
thunderstorms possible across the distant interior. Above
normal temps will persist into this weekend into early next
week. Humidity will be a bit less...but temps may be a few
degrees higher may require additional Heat Headlines especially
Sunday and Monday. Main risk for a period of more widespread
showers and thunderstorms with torrential rainfall later Friday
into early Saturday. Another round of some organized showers and
thunderstorms may occur Monday and/or Tuesday.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
10AM Update:

12z guidance is starting to roll in, but at first glance, there
does not appear to be a whole lot of change since the previous
runs of the hi-res guidance. The main forcing from Beryl and the
shortwave stay well to the north and west of southern New
England. Although instability continues to build to near 2000
J/kg per SPC meso analysis, convection will have a tough time
firing this afternoon with large amounts of capping to overcome
and little to no forcing. Low status clouds that have formed due
to southerly flow and very high dewpoints will be slow to clear
this morning, further not helping the chances for convection
this afternoon.

Today

Warm/moist air mass remains in place today with an uptick in surface
dewpoints to the mid 70s. This will be accompanied by increased deep
layer moisture as PWATs are likely to approach 2 inches across much
of southern New England. With the increased moisture will come
increased cloud cover, but the overall tropical air mass will
continue to support heat advisory conditions (heat index>95) despite
less sunshine. Confidence in this aspect of the forecast is on the
moderate to high side. Confidence is lower with respect to
thunderstorm potential across the interior as the remnants of what
was once Hurricane Beryl lifts into the Ohio River Valley. Forcing
for ascent associated with the remnant circulation is expected to
trigger strong to severe thunderstorms across portions of New York
and northern New England this afternoon. The risk for such storms is
more marginal across southern New England with the greatest risk
across west/northwestern MA. Similar to what was observed yesterday,
any storms that develop would have the potential to produce heavy
downpours and damaging wind gusts. There is also a low risk for some
hail or even an isolated tornado. Confidence in impacts to southern
New England is low given the strongest forcing will be focused to
the north and west, but residents west of Worcester will need to
keep a close on the sky this afternoon.

&&

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

Low temperatures overnight will once again be bounded by dewpoints
in the low to mid 70s. Expect fog and low stratus to develop across
most of southern New England with the lowest cloud bases focused to
the south and east where dewpoints will be highest. A few showers
and thunderstorms may be possible after midnight as forcing
associated the remnant circulation of Beryl moves over The
Northeast.

Tomorrow

By tomorrow morning, forcing associated with the remnant circulation
of Beryl will lift northeast away from southern New England. This
should bring an end to any nocturnal shower/thunderstorm activity
from the night before, allowing for some clearing by the afternoon.
Lower cloud bases will continue to persist closer to the south
coast, but some breaks of sun will be possible there as well. Heat
advisory may need to be extended into tomorrow, but confidence was
not high enough to extend with this update. Surface temps are a bit
lower than previous days with upper 80s/low 90s more common.
Dewpoints will likely continue to hover in the mid 70s, but if they
reach the upper 70s then heat indices of 95+ will certainly be
attainable. Atmosphere will remain unstable tomorrow afternoon so
there will continue to be a risk for an isolated thunderstorm, but
with not a lot of forcing to work with we are not currently
expecting anything widespread or persistent.

&&

.LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/...
Key Points...

* Above normal temps into early next week with a bit less humidity,
  but temps a tad higher may require additional Heat Headlines

* Main risk for a period of widespread showers & t-storms with
  locally torrential rain will be later Fri into early Sat

* Another round of organized showers/t-storms possible Mon and/or Tue

Details....

Upper level ridging over the Atlantic will flatten out a bit this
weekend into early next week. This should allow the humidity to back
of at least a bit...but above normal temps will continue. In
fact...the westerly flow may allow temps to get a bit higher despite
a bit of a relief in the humidity. Regardless...additional Heat
Headlines will likely be needed especially Sunday and Monday. High
temps will generally be in the upper 80s to the lower 90s with
perhaps even some middle 90s early next week away from any localized
marine impacts near the coast.

The main risk for a period of widespread showers & t-storms appears
to be later Friday into early Sat. This is when shortwave energy
gets pulled northward as a frontal boundary sags southward. How this
unfolds remains uncertain...but if things line up correctly
localized torrential rainfall/localized flash flooding would be
possible given Pwats greater than 2 inches.

The other potential we will have to watch is the risk for another
round of some showers/t-storms sometime Mon and/or Tue. The flow
turns more westerly aloft with some shortwave disturbances will
likely cross the region. Given the flow is more westerly...mid level
lapse will be steeper and perhaps a greater risk for severe weather
if wind fields are strong enough. The CSU Machine Learning Probs do
indicate decent severe probs in their Day 6-7 forecasts...so
something will have to keep a close eye on with later forecasts.

&&

.AVIATION /17Z WEDNESDAY THROUGH SUNDAY/...
Forecast Confidence Levels:

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


Rest of Today...Moderate Confidence.

IFR status that had spread over much of the interior has
scattered out with only periods of MVFR from diurnal cumulus.
The only exception to this is the South coast including the
Islands where a thick status deck will likely remain for much
of the day. As for thunderstorm chances, thinking the main
threat is well west of southern New England and unlikely to
reach western MA or CT today.

Tonight...Moderate confidence.

IFR/LIFR conditions spread northward again with strong
southerly flow. Strong LLJ will bring windshear to the Cape and
Islands tonight, along with scattered showers and possibly a
rumble of thunder across the region. Winds remain gusty out of
the SSW at 20-25 knots.

Thursday...High confidence

Gradual improvements from IFR to MVFR/VFR late tomorrow
morning. Winds remain gusty out of the SSW at 20-25 knots. Low
chance for a weak afternoon shower.

Thursday night...High Confidence

VFR/MVFR with localized areas of mainly across the Islands.
Winds turn westerly and become light at 5-10 knots, except over
the Cape and Islands where winds will remains southerly at
15-20 knots.


KBOS TAF...High confidence in TAF.

VFR today with gusty SSW up to 25 knots. MVFR this evening, then
IFR overnight with continued gusty SSW winds. Gradual clearing
tomorrow morning with VFR expected by the afternoon.

KBDL TAF...High confidence in TAF.

VFR with pockets of MVFR this afternoon. Low chance for a shower
or thunderstorm this afternoon. IFR status deck expected to
spread NW again tonight with scattered showers and possibly a
rumble of thunder. Gradual clearing to VFR tomorrow.

Outlook /Thursday Night through Sunday/...

Thursday Night: Mainly MVFR, with areas VFR possible. Breezy.
Chance SHRA, slight chance TSRA.

Friday through Friday Night: Mainly VFR, with areas MVFR
possible. Breezy. Chance SHRA, chance TSRA.

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

Saturday Night: Mainly VFR, with local MVFR possible. Slight
chance SHRA, isolated TSRA.

Sunday: VFR.

&&

.MARINE...
Forecaster Confidence Levels:

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

Marine

Today through Tomorrow

Warm/humid air mass will support areas of fog over the coastal
waters, especially during the overnight hours. Winds increase out of
the southwest today to 10 to 15 knots with 20+ knot gusts possible.
This trend continues into Thursday with SCY wind gusts likely over
the south coastal waters. Increasing southwest flow will support
seas rising to 4 to 6 feet over the southern marine zones as well.

Outlook /Thursday Night through Sunday/...

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

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

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

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

Sunday: Winds less than 25 kt.

&&

.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 MAZ003>007-
     010>019-026.
RI...Heat Advisory until 8 PM EDT this evening for RIZ001>004.
MARINE...Small Craft Advisory from 8 AM Thursday to 8 AM EDT Friday for
     ANZ232>235-237-254.
     Small Craft Advisory from 5 AM Thursday to 8 AM EDT Friday for
     ANZ255-256.

&&

$$

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