265
FXUS61 KBOX 010227
AFDBOX

Area Forecast Discussion
National Weather Service Boston/Norton MA
1027 PM EDT Fri May 31 2024

.SYNOPSIS...
High pressure over the Ohio Valley Friday builds slowly east this
weekend and crest over New England Sunday. This will provide dry
weather along with warm days and cool nights. The next chance of
showers, albeit very low, is Sunday night as weak low pressure
tracks south of the region. High pressure brings warm and dry
weather through the middle of next week, then the weather pattern
becomes unsettled toward the end of the week as a frontal system
approaches from the west.

&&

.NEAR TERM /THROUGH SATURDAY/...
10:30PM - No forecast changes, see 7pm discussion for details.

7 PM update...

Diurnal CU is dissipating but batch of mid level clouds are
rotating south across eastern half New Eng this evening. These
clouds are reflected in mid level RH fields which show moisture
pushing off the coast later this evening. Clear skies will
follow setting the stage for good viewing conditions tonight for
the possible aurora. Visit swpc.noaa.gov for more information
regarding the possible magnetic storm. Dry NNW flow aloft will
maintain a very dry airmass across SNE, with dew pts in the 30s
and 40s. This combined with mostly clear conditions and a weak
NW pressure gradient, will support another night of chilly
temps. Thus, we will lean toward the cooler MOS guidance to
derive lows tonight, mainly in the mid to upper 40s in the
suburbs. Low to mid 50s elsewhere, including the city of Boston
and the high terrain, where winds will likely not decouple.
Don`t think we will see much if any patchy fog tonight given the
dry airmass, with dew pts as low as the mid to upper 30s at 2
pm.

&&

.SHORT TERM /SATURDAY NIGHT/...
230 PM update...

* More fabulous weather, sunshine and warm but low humidity

Saturday...

As we flip the calendar to June 1st (opening day for hurricane
season), our dry, pleasant weather continues. This is courtesy of
closed low over the Maritimes combined with ridge axis over the
eastern Great Lakes, continuing to provide a dry NNW flow/airstream
across SNE. Almost a rinse and repeat weather pattern from today.
Hence, lots of sunshine and another nice temp recovery from morning
lows in the 40s and 50s, warming into the upper 70s and lower 80s,
along with comfortable humidity (dew pts in the 40s!). Another day
of spectacular weather. Only wrinkle to the forecast is possible
afternoon seabreeze for eastern MA. As closed low exits the
maritimes and dives southward, shallow cool air spreads across the
Gulf of ME and westward toward MA. This cooler air just offshore
combined with a weakening pressure gradient supports seabreeze/cool
maritime air to come onshore. Thus, could have temps falling through
the 70s and into the 60s during the afternoon along the coast.
Otherwise, another gorgeous day on tap for MA/RI/CT.

Saturday night...

Deep layer ridge crest over the region Saturday night into Sunday
morning, continuing our dry and cool weather pattern. Not as chilly
as previous nights but still cool for early June. Followed the
cooler MOS guidance to derive mins, with forecast lows mainly in the
50s, but a few upper 40s in the normally cooler suburbs. Dew pts not
quite as low as today, therefore patchy fog is possible.

&&

.LONG TERM /SUNDAY THROUGH FRIDAY/...
Key Points...

* Warm and mainly dry weather through the middle of next week

* Unsettled pattern late in the week with increasing risk of showers

Details...

Warm and mainly dry conditions expected through the middle of next
week as mid level ridging in control for much of this period. Weak
shortwave moving east from the Gt Lakes temporarily breaks down the
ridge on Sunday but not expecting much more than some extra cloud
cover as column moisture is limited. For Sun night, another
shortwave and area of enhanced moisture is forecast to track mostly
south of New Eng. There is a low risk for a few showers near the
south coast but bulk of rainfall will likely remain to the south.
Otherwise, dry through Wed with above normal temps well into the 70s
to lower 80s, but cooler along the immediate coasts due to sea-
breezes.

Forecast uncertainty increases toward the end of the week as
amplifying trough digs into the Gt Lakes with shortwave energy
rotating around the trough. Shower chances will be increasing but
timing and extent of showers and rainfall amounts are uncertain as
there are significant model differences with the timing of the front
and where a potential frontal wave develops. We followed NBM
guidance which indicates chance of showers both days and cooler
temps.

&&

.AVIATION /03Z SATURDAY THROUGH WEDNESDAY/...
Forecast Confidence Levels:

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

00z update...

Tonight...High confidence.

SCT-BKN mid level cloud bases give way to SKC. Diminishing NW
winds.

Saturday... High confidence.

VFR and dry. NNW winds less than 10 knots will give way to afternoon
seabreezes along the coast.

Saturday night...high confidence.

VFR, dry weather and light/variable winds. MVFR in patchy fog
possible.

KBOS TAF...VFR, dry and NW winds 10-15kt with gusts up to 20 kt at
times, diminishing after sunset. Rinse and repeat for Saturday,
except seabreeze will develop late morning and afternoon.

KBDL TAF... VFR, dry and NW winds 5-15 kt.

Outlook /Sunday through Wednesday/...

Sunday through Tuesday Night: VFR.

Wednesday: VFR. Slight chance SHRA.

&&

.MARINE...
Forecaster Confidence Levels:

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

230 PM update...

Through Saturday night...

Very pleasant boating conditions, with weak high pressure over the
OH Valley late Friday, slowly building east and cresting over New
England early Sunday. This will provide light winds, locally onshore
along with dry weather and excellent vsby to the horizon. The only
negative, is that water temps remain chilly, only 55-60 degs.

Outlook /Sunday through Wednesday/...

Winds less than 25 kt.

&&

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

&&

$$

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