-- Discussion containing changed information from previous version are highlighted. --
795
FXUS61 KBOX 150148
AFDBOX

Area Forecast Discussion
National Weather Service Boston/Norton MA
948 PM EDT Tue May 14 2024

.SYNOPSIS...
High pressure offshore provides mild conditions and mainly dry
weather tonight and Wednesday. Although, can`t rule out a few
brief showers at any given time, especially across CT and
western-central MA. Low pressure passing to our south will
likely result in a period of showers for the first half of
Thursday...at least south of the Massachusetts Turnpike.
Otherwise...dry weather should dominate Friday through the
weekend other than a spot shower or two. Temperatures will
average below normal especially along the immediate coast with
onshore flow Thursday through the weekend...but a warming trend
is expected early next week.

&&

.NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/...

-- Changed Discussion --
10 PM Update...

No significant changes made to the forecast with this update.
Clouds, which yielded a brilliant sunset, continue to advance
northeast while rain showers remain suppressed just southwest of
our CWA. Anticipating some light showers will make their way
into central Connecticut before sunrise.

7 PM Update...

* Increasing clouds & mild overnight with lows in the 50s
* A few showers possible toward daybreak in western MA/CT

Lingering upper level ridging across southern New England has
kept the scattered diurnal showers to our north and west today.
This ridging will gradually slide further east tonight allowing
for increasing mid-high level cloudiness to overspread
the region from shortwave energy across the Ohio Valley.
Still expect dry weather to generally prevail...but warm
advection will probably be enough for a few showers to
develop toward daybreak across western MA/CT. Previous
forecast handles this well in the next paragraph.

With sunset SSW winds will begin to diminish. Scattered showers
over NYS will likely erode as the activity moves east into
drier/more stable airmass over SNE. However, later tonight as
closed low currently over TN/OH valley advects eastward,
deepening moisture and forcing for ascent will increase
somewhat, yielding a low risk for a few showers overnight across
CT into western-central MA. Otherwise a dry and mild night
ahead, with lows only in the 50s, above normal for mid May.
-- End Changed Discussion --

&&

.SHORT TERM /6 AM WEDNESDAY MORNING THROUGH WEDNESDAY NIGHT/...
Wednesday...

Enough ridging may linger for a mostly dry day, especially
across RI and eastern MA. A few showers possible across CT into
western-central MA, where some differential heating across the
hilly terrain may be in play. Otherwise, a mainly dry day with
even be some sunshine Wed across RI and eastern MA, more clouds
westward into CT and western/central MA. This partial sunshine
will combine with warm temps aloft and yield highs 70-75, 60s
along the coast where light onshore flow/seabreeze develops. Dew
pts in the 50s will also provide a mild feel to the airmass.

Wednesday night...

Closed low southwest of New England begins to circulate deeper
moisture and low level easterly jet into CT/RI and southeast
MA. This is where the risk of rain is highest. Some uncertainty
how far north this rain shield will pivot, as mid level low
tracks ESE. Thus, rain shield may remain south of the Mass Pike.
Mild temps continue with lows in the 50s. Light south winds
become east by Thu morning.

&&

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

* Showers likely the first part of Thu at least south of I-90
* Highs Thu-Sun...55-65 on immediate coast & 65-75 distant interior
* Mainly dry Fri/Sat/Sun...but clouds & a spot shower at times
* Warming trend likely early next week

Details...

Thursday...

Low pressure will be passing south of the Benchmark on Thu. There is
uncertainty with the northern extent of the rain shield especially
given limited baroclinicity this time of year...it can often be
quite challenging. Current thinking is that we probably will see a
period of showers during the first part of Thu...at least to the
south of I-90. Later shifts will need to make adjustments depending
on model trends. Onshore flow will likely hold high temps in the
upper 50s to the lower 60s on the immediate coast & 60s/near 70
further inland.

Friday/Saturday/Sunday...

High pressure over the Canadian Maritimes will combined with a
distant offshore low pressure system...Fri into the weekend. This
will generate an onshore flow and keep temps cool/below normal
especially along the immediate coast. Further inland...temps more
tricky and dependent on the amount of solar insolation. There might
be clouds at times with the onshore flow...but also periods of
sunshine as drier air may get circulated around the high pressure in
the Maritimes. Therefore...thinking high temps generally in the 55
to 65 degree range along the immediate coast & between 65 and 75
across the distant interior.

High pressure nosing down from the Maritimes may be enough to keep
most of the precipitation risk to our west and south Fri/Sat/Sun. We
may see a spot shower or two...but overall thinking dry weather
dominates.

Early Next Week...

There are some indications that the upper level energy to our south
will weaken and also get suppressed further south. This should allow
for some rising height fields and warming temperatures. There is
uncertainty as to how quick and to what magnitude this process may
occur...but thinking a warming trend is in the cards.

&&

.AVIATION /02Z WEDNESDAY THROUGH SUNDAY/...
Forecast Confidence Levels:

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

00z TAF Update...

Tonight...High Confidence.

Mainly VFR conditions prevail tonight despite increasing
mid-high level cloudiness from west to east. That being
said...We may have to watch for low clouds and fog patches
developing late near the Cape and Islands with increasing low
level moisture and a cooling boundary layer. A few showers may
develop toward daybreak across western MA/CT...but conditions
should remain VFR to at worst marginal MVFR. Gusty winds
diminish after sunset...but winds will remain S tonight but will
become rather light.

Wednesday...Moderate Confidence.

A broken deck of VFR-MVFR ceilings are expected with the
tendency for the lower conditions to be found across interior MA
& CT. Dry weather dominates...but a few showers are possible
mainly northwest of I-95. S winds 5 to 10 knots...but localized
sea breezes are possible during the afternoon along portions of
the immediate coast.

Wednesday night...Moderate Confidence.

Light S-SE winds become east overnight. VFR conditions become
MVFR overnight, as rain shield comes onshore to the south coast
of CT/RI/MA. Forecast uncertainty in how far north this rain
shield tracks overnight.

KBOS TAF...High confidence in TAF. The biggest uncertainly is
the potential for an ESE sea breeze for a time Wed afternoon.

KBDL TAF...High confidence in TAF.

Outlook /Thursday through Sunday/...

Thursday: Mainly MVFR, with areas VFR possible. Breezy. Chance
SHRA.

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

Friday through Friday Night: VFR. Breezy.

Saturday: Mainly VFR, with local MVFR possible. Breezy. Slight
chance SHRA.

Saturday Night: Mainly MVFR, with areas IFR possible. Breezy.
Slight chance SHRA.

Sunday: Mainly MVFR, with local IFR possible. Breezy. Slight
chance SHRA.

&&

.MARINE...
Forecaster Confidence Levels:

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

7 PM Update...

Tonight...

We will allow the near shore small craft headlines for SSW gusts
up to 25 knots to expire at 8 pm with the loss of diurnal
heating. Southerly winds should diminish. High pressure
offshore provides mainly dry weather tonight, but patchy fog may
develop over the southern MA/RI waters.

Wednesday...

Weak high pressure offshore results in light S-SE winds. Mainly
dry weather and any morning fog burns off by midday with good
vsby thereafter.

Wednesday...

Low pressure south of New England drifts north, with increasing
east winds 15-20 kt toward Thu morning. Vsby lowers to 1-3 miles
in areas of fog and rain, especially southern MA and RI waters.

Outlook /Wednesday Night

Thursday through Thursday Night: Low risk for Small Craft
Advisory winds with gusts up to 30 kt. Areas of rough seas.
Chance of rain showers.

Friday: Moderate risk for Small Craft Advisory winds with gusts
up to 30 kt. Seas up to 5 ft. Slight chance of rain showers.

Friday Night: Low risk for Small Craft Advisory winds with
gusts up to 25 kt. Seas up to 5 ft.

Saturday: Winds less than 25 kt. Seas up to 5 ft.

Saturday Night through Sunday: Winds less than 25 kt. Seas up
to 5 ft. Slight chance of rain showers.

&&

.BOX WATCHES/WARNINGS/ADVISORIES...
-- Changed Discussion --
CT...None.
MA...None.
RI...None.
MARINE...None.
-- End Changed Discussion --

&&

$$

SYNOPSIS...Frank/Nocera
NEAR TERM...Frank/Nocera/KS
SHORT TERM...Nocera
LONG TERM...Frank
AVIATION...Frank/Nocera
MARINE...Frank/Nocera