427
FXUS61 KBOX 271342
AFDBOX

Area Forecast Discussion
National Weather Service Boston/Norton MA
942 AM EDT Fri Sep 27 2024

.SYNOPSIS...
Drying out today as high pressure builds in from the north and
remains through Monday. Near to above normal temperatures
through Monday with partly to mostly cloudy skies. The next
chance of rain showers comes toward the middle of next week.

&&

.NEAR TERM /THROUGH TONIGHT/...

10 AM Update:

Forecast appears to be on track. Made some minor tweaks just to
account for new guidance and latest observations. Some showers
are lingering around the Islands and southern RI, but they
should not be around for much longer.

Previous discussion:

Northern stream trough lifts off to the NE,
but the cold front stalls near or just south of the region
today. Soundings show low to mid-level cloud cover will take
time to dissipate, possibly lasting into the afternoon. Even as
low clouds dissipate, cirrus clouds ahead of the upper level cut
off low move over the region today. Any sun that can be
realized will likely be filtered. Even with less sunshine today,
850mb temps around +11C will allow high temps to reach the mid
to upper 70s, with a low chance at 80F in the CT river valley.
Winds today will be light out of the north with localized sea
breezes.

&&

.SHORT TERM /SATURDAY/...
High-level cirrus clouds remain over the region as the upper-level
cut-off low remains stalled over the southeastern US.  This will
prevent perfect radiation cooling conditions, but with light and
variable winds, opted to blend cooler MOS guidance with the NBM.
Lows should drop into the low to mid-50s, with upper 40s possibly in
the high terrain.

High pressure drops down from northern New England on Saturday,
which will flip winds back to the ENE.  The onshore flow will bring
high temps back down to the upper 60s to low 70s.  High-level cirrus
begins to dissipate, but more strato cumulus moves in off the ocean,
meaning skies on Saturday will likely feature more clouds than the
sun.

&&

.LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/...
Highlights...

* Dry & very pleasant weather through early next week

* Next chance of rain showers comes Tue or Wed followed by more dry
  weather.

* Seasonable temperatures become cooler than average toward the
  middle of next week.

Details...

Mid level ridging and surface high pressure will continue to be the
dominant weather feature through at least Monday with subsidence
beneath the high keeping rain out of the forecast. Even so, clouds
will be plentiful thanks to persistent onshore flow around the high
that sticks around from the weekend into at least Tuesday. This also
acts to keep temperatures cooler, below average each day with highs
in the 60s and lows in the 50s. The coolest spots will be right
along the east coast.

The pattern begins to change around Tuesday as we see an upstream
shortwave/surface frontal system approaching from the Great Lakes.
This will also act to pull north a coastal low which may strengthen
as it approaches southern New England. How exactly this trough
evolves is still a low confidence part of the forecast but with a
1.75" PWAT plume out ahead and a 40 kt LLJ, rain showers are likely
Tue/Tue night into Wednesday. Beyond that dry weather looks to
return with a building ridge.

&&

.AVIATION /14Z FRIDAY THROUGH TUESDAY/...
Forecast Confidence Levels:

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

Rest of tonight...Moderate Confidence

Rain continues to dissipate inland while a heavier band remains
over the Cape and Islands. That band should move off shore
before sunrise. Guidance is mixed on how quickly CIGS lift to
VFR with some guidance hinting at radiation fog developing with
all the residual moisture around from yesterdays rains.

Today...High confidence.

VFR with light northerly winds. Localized sea breezes develop near
the coasts.

Tonight...High Confidence.

VFR with light and variable winds. Patchy radiation fog
possible esspically in the northern CT river valley.

Saturday...High Confidence

VFR with east winds at 5-10 knots.

BOS TAF...Moderate Confidence in TAF.

VFR today with light NNW winds. Sea breeze should develop late
this morning to early this afternoon.

BDL TAF...Moderate Confidence in TAF.

VFR today with light northerly winds

Outlook /Saturday Night through Tuesday/...

Saturday Night through Monday: VFR.

Monday Night: VFR. Slight chance SHRA.

Tuesday: VFR. Breezy. Chance SHRA.

&&

.MARINE...
Forecaster Confidence Levels:

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

Today through Saturday...High confidence.

Light and variable winds today and tonight will finally allow
seas to drop below 5ft for all offshore coastal zones.  Winds turn
east Saturday at 5-10 knots in the northern waters and 10-15 knots
in the southern waters.

Outlook /Saturday Night through Tuesday/...

Saturday Night: Winds less than 25 kt. Seas locally approaching
5 ft.

Sunday through Sunday Night: Winds less than 25 kt.

Monday: Winds less than 25 kt. Seas locally approaching 5 ft.

Monday Night: Winds less than 25 kt. Seas locally approaching
5 ft. Slight chance of rain showers.

Tuesday: Winds less than 25 kt. Seas up to 5 ft. Chance of rain
showers.

&&

.BOX WATCHES/WARNINGS/ADVISORIES...
CT...None.
MA...None.
RI...None.
MARINE...Small Craft Advisory until 2 PM EDT this afternoon for ANZ250-
     254.
     Small Craft Advisory until 11 AM EDT this morning for ANZ255.

&&

$$

SYNOPSIS...BW/KP
NEAR TERM...Hrencecin/KP
SHORT TERM...KP
LONG TERM...BW
AVIATION...BW/KP
MARINE...BW/KP