Small Craft Advisory 50, NWS Boston/Norton, MA

Area Forecast Discussion
National Weather Service Boston/Norton MA
242 AM EDT Fri Apr 11 2025

.SYNOPSIS...
A fast moving disturbance will bring rain and wet snow to the region
later tonight...but not expecting an impact to travel. Cloudy but
generally dry for Friday, but we expect another soaking, windswept
rain event for late Friday night into Saturday with some wet
snow/ice possible at the onset across the interior high terrain.
Additional rain possible in eastern New England on Sunday. Milder
temperatures are on top for the first half of next week.

&&

.NEAR TERM /UNTIL 6 AM THIS MORNING/...
Key Messages...

* Rain & Wet Snow arrives from west to east between 8 pm & 2 am with
  Ptype trending to mainly wet snow away from south coast

* 1-2" of wet snow accumulation possible mainly across the interior
  high terrain overnight but with roadways remaining generally wet

Shortwave trough will lift across the eastern Great Lakes tonight.
This will induce a modest southerly LLJ and with ample moisture
precipitation will overspread the region from west to east between 8
pm and 2 am. Ptype might be rain at the onset in the lower
elevations...but given the thermal profiles we should see
dynamic/adiabatic cooling processes flip most locations over to wet
snow at least away from the south coast later this evening into the
overnight hours. Not expecting much of an impact given temps mainly
above freezing and the time of year. However...we may see 1-2" of
wet snow on grassy surfaces mainly across the interior high terrain.
Some very minor accumulations are possible on grassy surfaces in the
lower elevations if there is enough intensity...but not an impact to
travel. Overnight low temps will mainly be in the lower-middle 30s.

&&

.SHORT TERM /6 AM THIS MORNING THROUGH 6 PM SATURDAY/...
Key Messages...

* Rain and wet snow departs Fri morning with mainly dry but
  cloudy weather the rest of the day and highs in the 40s to near 50

* Rain overspreads the region late Friday night from south to north
  with some wet snow/ice possible across the interior high terrain

Details...

Friday...

The shortwave and deeper moisture will be lifting to the
north...bringing an end to any remaining rain or wet snow Fri
morning. Otherwise...high pressure across eastern Canada will result
in ENE low level flow and skies remaining rather cloudy. High temps
will mainly be in the 40s to near 50 with the coolest temps along
the coast.

Friday night...

Low pressure emerges off the mid Atlantic coast and slowly lifts
northeast Fri night. While much of Fri evening will be
dry...precipitation will begin to overspread much of the region from
south to north after midnight. Ptype will mainly be rain in the
lower elevations, but high pressure over Quebec will result in
marginally cold enough air for a bit of wet snow/ice across parts of
the interior high terrain. It is possible that some locations across
the high terrain see minor snow accumulations along with a bit of
ice. Later shifts may have to consider a Winter Weather Advisory
depending on model trends. Low temperatures will mainly be in the
30s. It will also becoming a bit breezy along the coast especially
after midnight.

&&

.LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/...
Key Messages:

* Dreary and unsettled through Sunday

* Steady rain lingers over the Cape and Islands Sunday, showers
  elsewhere.

* Warmer to start the week before the chance for more rain returns
  with another frontal system midweek.

Details...

Brief break in rainfall Saturday night as low pressure becomes
vertically stacked under the cutoff low. The second in a series of
low pressure systems passes close to but south of southern New
England, leading to the return of rain chances across the eastern MA
coast Sunday. Totals for this event will likely be a bit lower, as
the rain associated with this should be lighter. Forecast soundings
indicate some drier air aloft while PWATs are still in the 0.7-0.75"
range along the eastern coast. These will likely fall as the day
progresses and dry air moves into the region. Still a bit of wiggle
room with the exact track of this secondary area of low pressure
which could impact eventual rainfall totals.

The trough associated with the weekend's unsettled weather is
expected to move offshore by the start of next week. Ridging and
surface high pressure builds in a bit Monday ahead of yet another
trough across the Great Lakes. N/NW winds shift south Monday
night/Tuesday morning with the arrival of a warm front, and low rain
chances make a return going into Tuesday. A deepening area of low
pressure near the southern Hudson Bay may push a strong cold front
through the region later Tuesday. Ensembles show 850 mb temps
plunging to between -5 and -10C behind this feature. 850 mb
temps of this magnitude would likely result in below-average
temps across the eastern CONUS. Temperatures to start the week
will likely be warmer, with highs on Monday and Tuesday reaching
the 60s. Cooler and possibly unsettled weather may make its
return by midweek with this frontal system.

&&

.AVIATION /06Z FRIDAY THROUGH TUESDAY/...
Low - less than 30 percent.
Moderate - 30 to 60 percent.
High - greater than 60 percent.

06z TAF Update:

Through 12z Friday: Moderate confidence.

IFR/MVFR for the interior MA/CT airports in -RASN and stratus,
with more of a MVFR/VFR borderline condition for eastern and
southern airports (BOS, BDL, PVD, Cape terminals). Pavement
temps too warm to support any accum on runways in the interior.
Precip to gradually shifts toward the northeast 09-12z, leading
to precip tapering off except for the northern airports.
MVFR/IFR cigs likely to linger after precip exits. Winds light
S (more calm/variable in interior), but will be backing some to
a SE/ESE around 4-7 kt into the pre-dawn/Fri AM push.

Today: Moderate confidence.

Widespread MVFR bases (perhaps lingering IFR for BAF/BDL/ORH
early) should continue into the morning. It looks ceilings may
improve to VFR/MVFR borderline for eastern airports around
15-17z, with better chance at MVFR ceilings lingering most of
the day west of ORH. SE/E winds 4-8 kt continue to back to NE by
late-AM/noontime, while increasing in speed to around 10 kt.
Stronger aftn NElys for the Cape and Islands, around 10-15 kt
gusts 20-25 kt.

Tonight through Saturday: Moderate confidence.

Through about 04z Sat, VFR for most, with VFR/borderline MVFR
ceilings for the interior. Conditions to deteriorate from south
to north after 04z-08z Sat, with categories going down to
widespread MVFR- IFR levels as steady precipitation moves
northward from the mid- Atlc/southern waters. There is high
confidence in sub-VFR conditions once precip begins, but
greater uncertainty in precip types. Potential for a wintry mix
of wet snow/rain mixed at times with sleet for airports north
and west of Interstate 95. Wintry p-types could linger well
into Sat with terrain airports having best chance at minor
slushy accums but runways probably should be wet. Stronger
confidence that BOS, PVD and Cape airports stay as a plain,
wind- driven rain at onset and continue into Sat.

NE winds continue to increase to around 10-15 kt tonight into
Sat, with gusts 20-24 kt for most, though around 30 kt for the
Cape and Islands.

KBOS TAF...Moderate confidence. Brief VFR deteriorates to MVFR
bases in light rain 07-12z Fri with winds shifting to SE/E.
Rain ends around 12z-13z with slow rise in bases to BKN VFR
levels around noontime (TEMPO 16-18z for residual MVFR cigs) as
winds become NE 4-8 kt. Should be VFR by Fri aftn but NE winds
increase to around 10-13 kt.

KBDL TAF...Moderate confidence. IFR in -SNRA thru around 09z Fri,
then precip should begin to taper off to the northeast. IFR
ceilings to trend to MVFR. Improvement to BKN VFR ceilings
possible but not as likely as further east. Light winds to trend
NE this morning, increasing in speed to around 5-10 kt this
aftn.

Outlook /Saturday Night through Tuesday/...

Saturday Night through Sunday: MVFR/IFR conditions possible.
Breezy. Chance SHRA.

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

Monday: VFR.

Monday Night: Mainly VFR, with local MVFR possible. Chance
SHRA.

Tuesday: Mainly VFR, with local MVFR possible. Breezy. Chance
SHRA.

&&

.MARINE...
Forecaster Confidence Levels:

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

Tonight through Friday night...High Confidence.

A weak pressure gradient will keep winds/seas below small craft
advisory thresholds tonight into Fri. However...high pressure over
Quebec coupled with approaching low pressure from the southwest will
result in increasing NE wind gusts of 25 to 35 knots late Fri and
especially Fri night. The strongest of the winds will be across the
southern outer-waters where we have hoisted a Gale Watch. We will
certainly need small craft advisories across the rest of the waters.

Outlook /Saturday Night through Tuesday/...

Saturday: Moderate risk for Small Craft Advisory winds with
gusts up to 30 kt. Rough seas up to 9 ft. Rain.

Saturday Night: Low risk for Small Craft Advisory winds with
gusts up to 25 kt. Rough seas up to 8 ft. Rain showers likely.

Sunday: Moderate risk for Small Craft Advisory winds with gusts
up to 25 kt. Rough seas up to 9 ft. Rain showers likely.

Sunday Night: Low risk for Small Craft Advisory winds with
gusts up to 25 kt. Areas of rough seas. Chance of rain showers.

Monday: Winds less than 25 kt. Local rough seas.

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

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

&&

.BOX WATCHES/WARNINGS/ADVISORIES...
CT...None.
MA...None.
RI...None.
MARINE...Gale Watch from this evening through Saturday morning for
     ANZ255-256.

&&

SYNOPSIS...Frank/FT
NEAR TERM...Frank
SHORT TERM...Frank
LONG TERM...FT
AVIATION...Loconto/Hrencecin
MARINE...Loconto/Hrencecin