847
FXUS61 KBOX 031936
AFDBOX

Area Forecast Discussion
National Weather Service Boston/Norton MA
336 PM EDT Thu Apr 3 2025

.SYNOPSIS...

A few Light rain showers are possible this evening with the
passage of a weak cold front. More light rain likely overnight
near the southcoast as the cold front stalls. Drying and
clearing trend for Friday with mild daytime temperatures.
Turning unsettled this weekend with rain chances both of the
days along with below normal temperatures on Saturday to
slightly above normal on Sunday. Though there is some
uncertainty with how warm it may become Sunday. Drying out
Monday, but cooler temperatures return for the week ahead with
unsettled conditions Tuesday and perhaps late next week.

&&

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

A weak cold front drops south through southern New England this
evening, bringing more scattered light showers and possibly a rumble
or two of thunder near the south coast, where residual instability
remains. The front wont make it much further than the south coast
before stalling as a weak low-pressure system rides along it
overnight. This will likely bring another round of light rain to the
areas, mainly along the south coast but as far north as the MA Pike.
Despite the cold fronts passage, we wont see much clearing or
cooling. Low to mid-level clouds will stick around all night and
help hold overnight lows in the upper 40s to low 50s.

&&

.SHORT TERM /6 AM FRIDAY MORNING THROUGH FRIDAY NIGHT/...

Dry northerly air pushes out any remaining showers by mid-Friday
morning, with clearing skies from north to south. With 850mb
temperatures still around +8C, high temperatures will be able to
jump back into the low to mid-60s, with low 70s possible in Eastern
MA. Winds remain from the NW Friday at 10-20mph.

Rising heights Friday night will keep things dry, but expect
increasing mid- to upper-level cloud cover ahead of the next
shortwave.  Calm winds overnight will help radiational cooling bring
lows into the upper 30s to low 40s.

&&

.LONG TERM /SATURDAY THROUGH THURSDAY/...

Key Messages:

* Less than ideal conditions this weekend with rain chances and a
  cooler feel due to a backdoor cold front.

* Cooler and unsettled conditions persist into early next week.

Saturday through Sunday Night: Anticipate broad area of high
pressure to build across southwestern Quebec, anticyclonic flow
brings a backdoor cold front and ushers cooler marine air as result
of the northeast to east flow. 925mb temperatures decrease Saturday
to +/-1C, resulting in afternoon highs from the middle to upper 40s.
The surface high shifts to the east and the warm front lifts north
which shifts wind direction to southwest, advecting warmer and more
moisture into southern New England by Sunday. A forecast challenge
on Sunday, how far north does the warm sector reach? The trailing
cold front is not too far removed. Deterministic guidance, have the
warm sector mostly suppressed to the south, with limited warmer air
aloft moving out before early afternoon, limiting heating potential
for the afternoon. Appears to be the theme amongst the deterministic
guidance, cooler than 00z run and moving the warm sector out quicker
too. Spread in temperatures are shown easily on DESI, viewing the
10th and 90th percentile of the NBM, has a spread of 20 degrees for
almost the entire region, the exception is Cape Cod and the Islands
where the spread is much less, less than 7 degrees. As result did
deviate from the warmer NBM solution by blending in the cooler
CONSMOS guidance, resulting highs are middle 50s to near 60F. As for
precipitation this weekend, PWATs range between 1.3" and 1.5" which
is 2-3 standard deviations above normal. Rain arrives late Saturday
morning into early afternoon, from west to east. Expect
precipitation to persist through Sunday as the associated low-
pressure system traverses the region Saturday night through Sunday
evening. During this time frame, cannot rule out rumbles of thunder,
SREF has fairly low probabilities of MUCAPE exceeding 250J/kg at 30%
across southwestern New England. As the cold front exits Sunday
night into early Monday morning, enough cold air advects in behind
the front and may change the rain to a sleet/snow mix in the higher
terrain of northern and western Massachusetts.


Monday though Thursday: Briefly drier conditions on Monday, though
the next system is not too far off as a low-pressure system moves
into northern New England from the Great Lakes region for Tuesday.
The exact positioning is uncertain as guidance ranges from roughly
Albany, NY to Montreal. The system lacks moisture, PWATs fall from
0.4" to 0.2" during Tuesday morning, but cold air aloft and marginal
surface temperatures in the higher elevations, AOA 1,000 FT, may
lead to a snow/rain mix, with spotty rain showers in the lower
elevations. A quick break on Wednesday is followed by another quick
moving system late next week. As for temperatures, trending slightly
below normal with highs in the 40s, but cooler across interior
southern New England in the mid 30s, this if for Monday thru
Wednesday, perhaps nearing the 50s Thursday. Lows in the 30s Monday
night, followed by lows in the 20s Tuesday night and Wednesday
night.

&&

.AVIATION /20Z THURSDAY THROUGH TUESDAY/...
Low - less than 30 percent.
Moderate - 30 to 60 percent.
High - greater than 60 percent.

Rest of Today...Moderate Confidence.

Widespread IFR stratus with light mist/drizzle. Areas of LIFR
with areas of dense fog developing along the south coast and
Cape/Islands mid- late afternoon. Increasing SW winds with
gusts to 25-35 kt developing.

Tonight...Moderate Confidence.

IFR/LIFR in the early evening hours ahead of a cold front. The
cold front moves from north to south between 01-05z this
evening. There could be some light showers associated with the
cold front which was handled with prob30s for -SHRA at most
terminals. CIGS will gradually rise back to MVFR/VFR levels
behind the cold front. Weak low pressure system traverse near
the south coast late overnight which will bring light showers
and MVFR CIGS through about 06-12z. These showers should stay
mainly south of the MA pike.

Friday... High Confidence

VFR. West/northwest winds at 10 knots gusting 20 knots.

Friday Night... High Confidence

VFR. Light northerly winds under 10 knots.

BOS TAF...Moderate confidence.

IFR/MVFR this afternoon with light mist/drizzle. Cold front
could bring some light showers this evening between 01-03z with
gradual improvement of CIGS to MVFR/VFR this evening.

BDL TAF...Moderate confidence.

IFR this afternoon with light mist/drizzle. Cigs gradually
improve to MVFR this evening. A weak low will bring light rain
overnight with gradual clearing conditions by morning.

Outlook /Saturday through Tuesday/...

Saturday: Mainly MVFR, with local IFR possible. Breezy. SHRA,
chance FZRA.

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

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

Sunday Night: Mainly MVFR, with local IFR possible. SHRA
likely.

Monday: MVFR/IFR conditions possible. Slight chance SHRA.

Monday Night: Mainly MVFR, with local IFR possible. Slight
chance SHRA, slight chance SHSN.

Tuesday: 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.

Gusty SW winds at 20-30 knots continue this evening before diminishing
as a cold front approaches and stalls near the southern waters.
Light rain showers are possible overnight as a weak low pressure
systems moves from west to east tonight. Winds shift NW at 10-15
knots late overnight and remain there for Friday.

Seas this evening remain elevated around 4-8 feet, diminishing to 3-6
feet by Friday morning. Seas drop to 2-4 feet by Friday
afternoon.

Outlook /Saturday through Tuesday/...

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

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

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

Sunday Night: Winds less than 25 kt. Areas of rough seas. Rain
showers.

Monday: Winds less than 25 kt. Local rough seas. Chance of rain
showers.

Monday Night: Winds less than 25 kt. Areas of seas approaching
5 ft. 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 10 PM EDT this evening for ANZ230.
     Small Craft Advisory until midnight EDT tonight for ANZ231-251.
     Small Craft Advisory until 5 AM EDT Friday for ANZ232>234.
     Small Craft Advisory until 11 AM EDT Friday for ANZ235-237.
     Small Craft Advisory until 1 AM EDT Friday for ANZ236.
     Small Craft Advisory until 8 AM EDT Friday for ANZ250.
     Small Craft Advisory until 8 PM EDT Friday for ANZ254>256.

&&

$$

SYNOPSIS...Dooley/KP
NEAR TERM...KP
SHORT TERM...KP
LONG TERM...Dooley
AVIATION...Dooley/KP
MARINE...Dooley/KP