087
FXUS61 KBOX 311415
AFDBOX

Area Forecast Discussion
National Weather Service Boston/Norton MA
1015 AM EDT Mon Mar 31 2025

.SYNOPSIS...
Areas of dense fog this morning, mild this afternoon with showers, a
cold front moves through this evening through the overnight with
heavy rain and embedded thunder. Showers come to an end across
eastern Massachusetts by mid morning then sunny for the afternoon,
with near normal highs. Dry weather Wednesday with temperatures
trending cooler. An approaching warm front may bring some showers to
the region Wednesday night. Milder temperatures arrive Thursday into
Friday with a round or two of showers possible but not a washout.
Temperatures trend cooler by next weekend with some more rain
possible by later Saturday and/or Sunday.

&&

.NEAR TERM /THROUGH TONIGHT/...
10 AM Update...

Fog is beginning to decrease as the warm front makes its way
north, but it is lingering in some parts of the interior. Winds
in post-frontal areas have shifted more to the southwest which
should continue to erode fog as it increases today.

Key Messages:

* Areas of dense fog this morning, mild this afternoon with showers,
  a cold front moves through this evening through the overnight with
  heavy rain and embedded thunder.

First batch of rain pushed through early this morning, now a few
spotty showers linger through roughly 7am. Like previous days will
have fog and drizzle as the lowest levels are saturated. Have issued
a Dense Fog Advisory for much of the area through 9am with the
exception of the south coast of RI & southeast MA through noon. Feel
the fog may linger longer there because of the warm air advecting
over the colder ocean water. Motorist and boaters should use extra
caution commuting this morning. Increasing southwest flow this
morning as result of the warm front passage will help erode fog away
from the coast line and help bring our temperatures into the 60s,
greatest temperatures are in the CT Valley and Merrimack Valley
where upper 60s are likely. Near the coast it is cooler in the 50s.
Breezy for much of today as well, southwest winds are 10 to 15 mph
with gust up to 30 mph. Next batch of rain comes in early afternoon,
CAMS show a weak line of showers pushing from west to east between
12pm and 4pm, followed by a more significant line of heavy rain and
embedded thunder. CAMS have this arriving as early as 6pm in SW CT,
then filling in over the rest of southern New England after 8pm
through the predawn hours of Tuesday. This line is associated with a
severe weather outbreak in the Midwest, not expecting severe weather
across southern New England, but thunder cannot be ruled out. SPC
placed southern New England under `general thunder` and areas of far
western MA and CT under a `marginal risk` for severe weather.
Limiting factors for severe weather is instability, MUCAPE values
this evening are between 100 to 500 units. This might be just enough
instability for rumbles of thunder, HREF prob thunder for CT/RI and
SE MA are at 30 to 50 percent. Downpours are possible with PWATs at
1.3" to 1.5", around 2.5 to 3 standard deviations above normal. That
said, widespread rain with amounts of 2/3" to 1" are likely, while
less likely are localized higher amounts of 1.5" across CT/RI/and SE
MA per the HREF 24 hour probability matched mean.

&&

.SHORT TERM /TUESDAY/...
Key Messages:

* Showers come to an end across eastern Massachusetts by mid morning
  then sunny for the afternoon, with near normal highs.

Tuesday starts with rain along and east of the I-95 corridor as the
cold front remains hung-up at the coast. Good news, late morning the
front exits and will have increasing sunshine and drier conditions
settle into the region, PWATs fall below 0.3" as high pressure moves
in from Canada. As mentioned above, with the passage of the front
wind direction veered to the northwest and with forecast soundings
depicting the boundary layer around 850mb and with winds aloft at 20
to 30 knots, will have periodic gusts up to 30 mph. Temperatures,
850mb forecast is -3C to -5C, should result in highs in the upper
40s and low 50s. zed higher amounts possible. Lows Monday night
will be in the 40s.

&&

.LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/...
Key Messages:

* Dry but chillier Tue night into Wed with lows in the 20s to the
  lower 30s and highs mainly in the 40s to near 50 CT River Valley

* A warm front brings a few showers Wed night into early Thu

* Much milder Thu into Fri with highs mainly in the 60s both days
  with perhaps a few showers, but dry weather will probably dominate

* Chillier next weekend with some rain likely sometime Sat into Sun

Details...

Tuesday night and Wednesday...

A 1035+ mb high pressure system building across Quebec and into New
England will result in dry but chillier air to work into the region
Tue night & Wed. 925T drop to between -4C and -8C which should allow
overnight low temps in the 20s to the lower 30s Tue night. The high
pressure shifts east of the region Wed which will allow the N flow
to turn more E. The result will be a dry day with highs mainly in
the 40s with the coolest of those temps likely on the eastern MA
coast. A few spots in the CT River Valley may reach 50.

Wednesday night and Thursday...

Low pressure will be lifting across the Great lakes Wed night and
into Quebec on Thu. The result will be a warm front lifting
northward across our region Wed night into Thu AM. This will
probably be accompanied with a few showers. The antecedent airmass
may be dry/cold enough to support a touch of sleet/freezing at the
onset...but given marginal temperatures not thinking there will be
much of an impact. Otherwise...thinking is that most of the showers
will be over by Thu afternoon behind the warm front. In fact...a
much milder southerly flow of air will work into the region for Thu.
Highs should top out well into the 60s for most locations.

Thursday night and Friday...

A cold front will slowly drop down from the north and cross the
region Thu night into Fri. This may result in another round of
scattered showers depending on where a surface wave tracks along the
cold front. Either way...do not expect a washout or a significant
rain event. Temps aloft fairly mild so think highs on Fri will again
be into the 60s.

Next Weekend...

High pressure passes to our north across Quebec and into the
Maritimes next weekend. At the same time...a wave of two of low
pressure will approach from the west. The result will be onshore
flow and cooler temps along with the potential for some rain
sometime Sat and/or Sun.

&&

.AVIATION /14Z MONDAY THROUGH FRIDAY/...
Low - less than 30 percent.
Moderate - 30 to 60 percent.
High - greater than 60 percent.

12z TAF Update...

Today...Moderate Confidence.

IFR-LIFR conditions dominate today. Morning fog some of which
was locally dense will burn off later in the morning and
afternoon...except it will persist or redevelop near the south
coast as high dewpoint air moves over the relatively cold ocean.
The low clouds on the other hand will remain in most locations
given ample low level moisture moves into our region. A few
showers will be possible at times...but the majority of the day
will be rain free at a given location. SSW wind gusts 20 to 30
knots with a few gusts up to 35 knots possible towards the Cape.
Lastly...LLWS will also be an issue today with a strong LLJ of
45 to 55 knots.

Tonight...Moderate Confidence.

Widespread showers with embedded downpours and perhaps a few
embedded t-storms will cross the region tonight ahead of and
along an approaching cold front. IFR-LIFR conditions will begin
to improve towards VFR after midnight across parts of the
interior and toward daybreak along the coastal plain. Some low
clouds and fog may linger through daybreak though towards the
Cape and Islands. SSW wind gusts of 20 to 30 knots during the
evening and up to 35 knots near the Cape and Islands. In
addition...LLWS will also persist this evening with the strong
southerly LLJ ahead of the cold front. The wind will begin to
shift to the NW behind the cold front after midnight with some
gusts of 20 to 25 knots.

Tuesday...High Confidence.

Any lingering low clouds/fog patches across the Cape/Islands scatter
out by mid morning. Otherwise...VFR conditions on Tue with some NW
wind gusts up to 25 knots.

BOS TAF...Moderate Confidence in TAF.

BDL TAF...Moderate Confidence in TAF.

Outlook /Tuesday Night through Friday/...

Tuesday Night through Wednesday: VFR. Breezy.

Wednesday Night: Mainly MVFR, with local IFR possible. Breezy.
Chance SHRA, FZRA likely.

Thursday: Mainly MVFR, with areas IFR possible. Windy with
gusts up to 30 kt. Chance SHRA.

Thursday Night: Mainly MVFR, with areas VFR possible. Breezy.
Chance SHRA.

Friday: Mainly VFR, with areas MVFR possible. Breezy. Chance
SHRA.

&&

.MARINE...
Forecaster Confidence Levels:

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

* Gale Watch converted to Small Craft Advisory

Today and Tonight: High Confidence.

Low visibilities due to fog and areas of light rain today as a warm
front pushes north today, which increases southwest flow gusting
between 25 and 30 knots, isolated higher gust of 35 knots possible,
but not enough confidence to issue a Gale Warning. Seas building up
to 6 to 8 feet across the outer waters with near shore waters 3 to 6
feet. A cold front approaches from the west tonight with heavy rain
and embedded thunder. Southwest wind veer to northwest by daybreak
with gusts 20 to 25 knots. Seas overnight increase, 7 to 9 feet for
the outer waters and southern near shore waters 5 to 7 feet while
eastern near shore waters are 4 to 6 feet.

Tuesday: High Confidence.

Cold front moves off shore with clearing skies by mid morning. Will
have northwest gusts up to 25 knots, seas near shore lower, between
3 and 6 feet, while seas off shore remain elevated at 6 to 8
feet.

Outlook /Tuesday Night through Friday/...

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

Wednesday: Winds less than 25 kt. Seas up to 5 ft.

Wednesday Night: Low risk for Small Craft Advisory winds with
gusts up to 30 kt. Areas of seas approaching 5 ft. Chance of
rain showers.

Thursday: Low risk for gale force winds with gusts up to 30 kt.
Areas of rough seas. Chance of rain showers.

Thursday Night: Low risk for Small Craft Advisory winds with
gusts up to 30 kt. Areas of rough seas. Chance of rain showers.

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

&&

.BOX WATCHES/WARNINGS/ADVISORIES...
CT...None.
MA...Dense Fog Advisory until noon EDT today for MAZ020>024.
RI...Dense Fog Advisory until noon EDT today for RIZ004>008.
MARINE...Small Craft Advisory until 8 AM EDT Tuesday for ANZ230>234-236-
     251.
     Small Craft Advisory until 8 PM EDT Tuesday for ANZ235-237-250-
     254>256.

&&

$$

SYNOPSIS...Frank/Dooley
NEAR TERM...Dooley/Hrencecin
SHORT TERM...Dooley
LONG TERM...Frank
AVIATION...Frank/Dooley
MARINE...Frank/Dooley