695
FXUS61 KBOX 102307
AFDBOX

Area Forecast Discussion
National Weather Service Boston/Norton MA
707 PM EDT Sat Aug 10 2024

.SYNOPSIS...
A cold front moving offshore will provide dry and comfortable
weather tonight. A weak wave of low pressure develops on the
offshore front Sunday, yielding increasing clouds across southern
New England, however dry weather will prevail. Most of the upcoming
workweek will feature generally dry weather with a mix of clouds and
sun, seasonable temperatures and low humidity levels. Isolated
showers and thunderstorms are possible both Monday and Thursday.

&&

.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
7 PM Update:

* Much less humid and cooler tonight

This Evening...

Dry weather prevails across all of SNE. Post frontal airmass
continues to spill across the region, with a west breeze 10-15
mph advecting lower dew pts into the 60s and now 50s across
western MA! Hence, much less humid trends the rest of today and
into tonight.

Overnight...

Beautiful weather tonight as the post frontal airmass continues to
advect across the region, with dew pts falling into the 50s regionwide!
This drier airmass combined with mostly clear conditions and light
west winds, will provide radiational cooling conditions. Given
this setup, we will derive min temps from the cooler MOS datasets,
supporting lows overnight in the mid to upper 50s for most locations!
The exceptions will be the coastline, Cape Cod, Islands and the
urban areas of Boston, Providence, Hartford and Worcester, where
mins will be in the 60s, but feeling cooler given dew pts in
the 50s. As for the risk of patchy fog, given diurnal drying
this afternoon combined with dew pts falling into the 50s, this
combination should preclude much if any radiational fog development.

&&

.SHORT TERM /6 AM SUNDAY MORNING THROUGH SUNDAY NIGHT/...
Updated: 3:30 PM

Sunday...

Closed low over Ontario today traverses eastward and ejects a modest
short wave toward New England Sunday. This yields mid/upper level
WAA across SNE, with sunshine at daybreak giving way to increasing
clouds thereafter into the afternoon, yielding filtered sunshine.
This short wave also induces a weak surface wave on the offshore
front, tracking south of New England. However, with the column being
so dry, not expecting any precip, just an abundance of mid level
clouds, that should thin for some late day sunshine. Not as warm
tomorrow given less sunshine and less humid too, as core of drier
air will be over the region Sunday. Nonetheless, very pleasant
conditions with highs in the low 80s, upper 70s high terrain and
along the south coast, along with dew pts in the 50s! Southwest
winds 10-15 mph, except southeast winds along the Plymouth
coastline.

Sunday night...

As weak surface wave south of New England exits east of our
longitude, cool/dry air get replenished on the backside of the
wave into SNE. Thus, another dry, cool night with comfortable
humidity. Given mostly clear conditions, light winds and a dry
airmass, followed the cooler MOS guid to derive mins, which
yields another night in the mid to upper 50s, except 60-65 along
the coast and islands, including the urban areas of Boston,
Providence and Hartford.

&&

.LONG TERM /MONDAY THROUGH SATURDAY/...
Key Points

* Seasonable and mainly dry conditions for much of the work week

* Low chance for an isolated shower/T-storm Monday afternoon, and
  again Thursday afternoon.

* Tropics are beginning to heat up and will be watched closely
  over the coming days and weeks.


Mainly dry and seasonable weather expected this week as surface high
pressure moves east from the northern Great Plains. With northerly
surface flow, high temperatures much of the week stick in the low to
mid 80s with dewpoints holding in the low to mid 60s. Even with high
pressure building in, cyclonic flow aloft and associated cold pool
will bring daily diurnal cumulus. A stronger shortwave passes
through the flow Monday afternoon which could bring isolated showers
and possibly a rumble or two of thunder. The limiting factor Monday
afternoon is that significant mid level capping will be in place.
Surface dewpoints will also be in the upper 50s to low 60s which
will limit the amount of instability that can build and break such a
significant CAP. Guidance currently indicated that 300-500 J/kg of
SBCAPE may be available Monday, but bufkit soundings show a very
skinny and short CAPE profiles, likely leading to just low topped
showers. The next chance for isolated showers/T-storms appears to be
Thursday as the core of the closed low and upper level cold pool
move right overhead. Surface instability looks limited again in the
300-500 J/kg range due to dew points in the low 60s and skinny cape
profiles.

Heading into next weekend and early next week, considerable
uncertainty exists with how the forecast evolves. Guidance seems to
be hinting at a shortwave trough exiting the Great Lakes, but large
differences in timing and amplitude exists among the difference
guidance sources. Another uncertainty to add to the mix is that the
tropics are starting to heat up. NHC is highlighting an area of high
chances for a tropical system to develop near the Lesser and Greater
Antilles over the next 7 days. A close eye will be kept on how this
system evolves and tracks over the next week.

&&

.AVIATION /23Z SATURDAY THROUGH THURSDAY/...
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 the period.

This evening and overnight...

VFR. Winds continue to diminish tonight becoming light out of
the WNW tonight.

Sunday...

Dry runways and VFR. Southwest winds around 10 knots. Should be
enough mixing to cause some 20 knot gusts tomorrow afternoon.
2kft winds should be strong enough to preclude a sea breeze for
eastern MA terminals, including KBOS.

Sunday night...

Continued VFR, dry weather and light winds.

KBOS TAF...High confidence. SW winds should be sufficient to
hold off a seabreeze.

KBDL TAF...High confidence

VFR, light/variable winds tonight before becoming SW Sunday
afternoon.

Outlook /Monday through Thursday/...

Monday: VFR. Isolated SHRA, isolated TSRA.

Monday Night through Wednesday Night: VFR.

Thursday: VFR. Slight chance SHRA, isolated TSRA.

&&

.MARINE...
Forecaster Confidence Levels:

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

Updated: 3:30 PM

Thru Sunday night...High Confidence.

Leftover southerly swells will slowly subside tonight. WSW winds
tonight yield dry weather and good vsby. Weak surface wave
tracks south of New England Sunday, but precip shield will
remain well offshore. Just a thin overcast with good vsby and SW
winds. More of the same Sunday night, light winds, dry weather
and good vsby.

Outlook /Monday through Thursday/...

Winds less than 25 kt.

&&

.BOX WATCHES/WARNINGS/ADVISORIES...
CT...None.
MA...High Risk for Rip Currents until 8 PM EDT this evening for MAZ007-
     015-016-019.
     High Surf Advisory until 8 PM EDT this evening for MAZ020>024.
RI...High Surf Advisory until 8 PM EDT this evening for RIZ006>008.
MARINE...Small Craft Advisory until midnight EDT tonight for ANZ235-237.
     Small Craft Advisory until 8 AM EDT Sunday for ANZ254>256.

&&

$$

SYNOPSIS...KP/Nocera
NEAR TERM...Nocera
SHORT TERM...Nocera
LONG TERM...KP
AVIATION...KP/Nocera
MARINE...KP/Nocera