-- Discussion containing changed information from previous version are highlighted. --
178
FXUS61 KBOX 020726
AFDBOX

Area Forecast Discussion
National Weather Service Boston/Norton MA
326 AM EDT Thu May 2 2024

.SYNOPSIS...
A weak low pressure will bring scattered showers near the coast
Thursday. High pressure north of our region will bring dry and
seasonable weather Friday and most of Saturday with onshore
winds. An approaching front should bring showers late Saturday
into Sunday. Dry and warmer weather is expected early next week.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...

-- Changed Discussion --
Today

3AM Update

South/southeasterly flow is resulting in increasing low-level
moisture at this hour. As the boundary layer continues to cool we
should see more filling in of scattered to broken areas of low
stratus across southern New England this morning. This trend has
been visible on latest GOES nighttime microphysics imagery. While we
will have a cloudy start to the day, we do anticipate plenty of
sunshine as winds take on a more west/west northwest direction and
advect drier air over southern New England. Expect the sun to
breakout across western MA/CT by late morning and maybe closer to
the early afternoon hours for areas along and east of I-495. Cloud
cover will be more prevalent across eastern MA, where a few showers
will be possible ahead of a short-wave trough digging southeast
across southern New England. The associated surface low pressure
circulation is forecast to travel over roughly the northeast border
of MA/NH. This path isn`t optimal for widespread precipitation, but
as mentioned previously, a few scattered showers for locations of
east of I-495 will be possible ahead of low this morning and on the
backend later this afternoon.

Areas across interior/western MA where sunshine will be more
abundant can expect a very warm afternoon with 15C temps at 925 hPa
supporting surface temperatures in the mid to upper 70s in the CT
River Valley. Low 70s/upper 60s will be more common east of the
Worcester Hills where the air mass will be cooler and the skies will
be cloudier. Overall a mild/quiet spring afternoon across the
forecast area.
-- End Changed Discussion --

&&

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

-- Changed Discussion --
Tonight

Winds shift to the northeast tonight as a surface low departs to the
southeast of southern New England. Onshore flow will support clouds
filling back in across the region. Overcast skies will prevent
temperatures from falling too far, so we can expect near to slightly
above normal low temperatures in the mid to upper 40s overnight.

Tomorrow

Onshore flow and east/northeasterly winds will support a
cooler/cloudier day tomorrow. Locations along the east coastline
will be much cooler than the interior in the face of onshore winds.
Areas along the coast will struggle to escape the low to mid 50s.
Temperatures will be more mild in the low to mid 60s across the
interior and warmest in The CT River Valley in the upper 60s.
-- End Changed Discussion --

&&

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

-- Changed Discussion --
Key Points:

 * Scattered showers late Saturday into Sunday
 * Warmup early next week

Upper ridge should maintain dry weather Saturday before it heads
offshore Sat night/Sun and allows scattered showers to reach SNE as
cold front crosses region. Certainly looks cooler over weekend,
especially Sunday with onshore winds once again.

Pattern becomes a little more complicated early next week as closed
low over Rockies becomes blocked by building ridge over Great Lakes.
Broad SW flow aloft will favor warming temperatures but how quickly
ridge flattens will determine when low pressure will reach western
Great Lakes, lifting warm front through SNE in the midweek time
frame. For now it looks dry Mon and Tue with increasing chances of
showers sometime Wed-Thu.
-- End Changed Discussion --

&&

.AVIATION /08Z THURSDAY THROUGH MONDAY/...
-- Changed Discussion --
Forecast Confidence Levels:

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

06Z TAF

Through 12Z...Moderate Confidence

GOES nighttime microphysics is beginning to show SCT to BKN
lower cloud bases filling in across southern New England. Still
expecting VFR ceilings to fall to IFR as we approach sunrise and
likely by 12Z. Light south winds.


Today...High Confidence in Trends

MVFR/IFR ceilings will lift/scatter out late morning/early
afternoon from west to east. Thus, VFR conditions should
prevails for most of the day. Winds increase close to 10 knots
and shift form south to southwest through about 18Z. Thereafter,
a weak low-pressure circulation will move over east/northeast MA
resulting in winds shifting to east and eventually northeast by
00Z. A few showers will be possible at BOS/BED and The
Cape/Islands terminals between 21 and 00Z.


Tonight...High confidence

IFR ceilings return overnight with steady northeast winds from
5 to 10 knots.

Tomorrow... High confidence.

MVFR/IFR ceilings lift/scatter out to VFR by mid-morning. Steady northeasterly winds becoming more
easterly after 18Z.


KBOS TAF...Moderate confidence

Not expecting LIFR ceilings for the morning push. MVFR should
be the prevailing flight category, but can`t rule out cloud
bases getting just below 1000 feet.

KBDL TAF...Moderate confidence.

IFR ceilings likely develop between 06-12Z but will improve to
VFR by 15Z.


Outlook /Friday Night through Monday/...

Friday Night: VFR. Chance SHRA.

Saturday: Mainly VFR, with local MVFR possible. Chance SHRA.

Saturday Night: Mainly VFR, with local IFR possible. Chance
SHRA.

Sunday: MVFR/IFR conditions possible. Chance SHRA.

Sunday Night: Mainly VFR, with areas IFR possible. Chance SHRA.

Monday: VFR. Chance SHRA.
-- End Changed Discussion --

&&

.MARINE...
-- Changed Discussion --
Forecaster Confidence Levels:

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

Today through Tomorrow

Conditions remain quiet across the coastal waters through tomorrow
with modest wind speeds and seas generally 3 feet or less. Southwest
winds for the first half of today become northeast as a weak low-
pressure circulation moves over the marine zones. Northeast winds
then persist through tonight and tomorrow.

Outlook /Friday Night through Monday/...

Friday Night: Winds less than 25 kt.

Saturday: Winds less than 25 kt. Slight chance of rain showers.

Saturday Night: Winds less than 25 kt. Chance of rain showers.

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

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

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

&&

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

&&

$$

SYNOPSIS...RM/JWD
NEAR TERM...Belk/RM
SHORT TERM...RM
LONG TERM...JWD
AVIATION...RM/JWD
MARINE...Belk/RM/JWD