000
FXUS61 KBOX 121923
AFDBOX

Area Forecast Discussion
National Weather Service Boston/Norton MA
323 PM EDT Sun May 12 2024

.SYNOPSIS...
Widely scattered showers this evening as an upper level low
pressure moves through New England. Chilly night tonight with
dry weather, then turning milder Monday with another round of
scattered afternoon showers possible across the interior. A
frontal system may bring more showers late Tuesday into
Wednesday, then drying out for the end of the week.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...

A mid-level cold pool over the region has led to diurnal clouds and
widely scattered showers this afternoon. With little or no effective
shear, these storms are slow moving, based off of KBOX, the average
storm motion is less than 10 mph. Good news, PWATs are less than
half of an inch, showers remain light. As we lose the heating of the
day, these showers will dissipate, ending this evening.

Cloud cover thins overnight, becoming partly clear with light
southwest winds. If we have enough clearing areas or radiation fog
is possible in western Massachusetts and northern Connecticut. Lows
are in the low and middle 40s, urban area around Boston likely a few
degrees warmer in the upper 40s.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM MONDAY/...

The setup for Monday has surface high pressure off shore and a mid-
level ridge to the northwest. 850mb jet noses to our north, but
transports higher PWATS, after a clear start to the day, clouds
increase during the afternoon. Showers remain possible during the
afternoon and evening hours, mainly for locations along and north of
the Mass Pike.

850mb temperatures increase to +5C to +7C, closer to normal compared
to the past few days. This leads to noticeably warmer
temperatures MOnday afternoon, afternoon highs are in the upper
60s and low 70s away from the coast. Do think there will be a
sea-breeze developing by mid/late morning, this will keep
coastal areas in the lower 60s.

Overnight the 850mb jet lifts north with the better forcing and
showers taper off from south to north. Clouds and a steady south to
southwest wind remain overnight, comfortable overnight lows in the
upper 40s and low 50s.

&&

.LONG TERM /MONDAY NIGHT THROUGH SUNDAY/...
Highlights

* Warm and windy on Tuesday ahead of an approaching low pressure
  system

* Rainy and unsettled Tuesday night through early Thursday

* Brief dry out on Friday followed by more unsettled weather next
  weekend

Tuesday

Deep southwest flow will support increasing temperatures and
moisture in southern New England on Tuesday. 925 hPa temps rise to
as high as 17C in some locations in southern New England so we are
expecting widespread temperatures in the 70s with mid to upper 70s
likely in the CT and Merrimack River Valleys. Coastal locations will
be  a bit cooler in the 60s. Model soundings suggest there should be
good mixing during the afternoon, so it looks like there will be
some gusty southwest winds on Tuesday with gusts from 20 to 30 mph
at times. There will be a mix of sun and clouds for most of the day,
but expect increasing cloudiness and precipitation chances as we
head into Tuesday evening, especially across western MA and CT.

Tuesday night through Thursday

The forecast becomes unsettled by Tuesday night as a surface low-
pressure system approaches southern New England. The details with
respect to timing and precipitation amounts are still only moderate
at best, but it does appear we will get a good soaking of rain
during most of Wednesday with 24 hour precip amounts likely between
0.5 to 1 inch. With a likely storm track southeast of southern New
England, we can expect north/northeasterly winds to develop as the
system passes to our south. In addition to the rainfall, this will
support cooler temperatures on Wednesday with highs confined to the
mid to upper 60s. Confidence drops off Wednesday evening as some
model guidance is resolving a slow departure of this system due to
downstream blocking. Thus, we may see some isolated to scattered
shower activity carry into Thursday. Depending on how fast the
coastal-low departs to the east, we may see some clearing later in
the day on Thursday and perhaps some seasonably warm temperatures in
the low 70s in the CT River Valley. Winds are likely to remain gusty
out of the northeast which will keep the coastal areas cooler.

Friday through Sunday

The aforementioned surface low should be well east of southern New
England on Friday when we`ll be left with a drier air mass that
should support a sunny end to the week. Temps look to be seasonable
with highs in the upper 60s to low 70s. Unsettled weather returns
next weekend as another low pressure system approaches from the
west.

&&

.AVIATION /19Z SUNDAY THROUGH FRIDAY/...
Forecast Confidence Levels:

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


Through 00z...Moderate confidence.

VFR. Widely scattered showers developing across southern New
England, with the greatest concentration across western MA and
NW CT. Light winds S-SE in the afternoon with sea-breezes along
the coast.

Tonight...High confidence in CIGs, but low confidence in fog
formation.

VFR. Low probability for patchy fog possible in prone radiator
locations. Light SW winds.

Monday...Moderate confidence.

VFR cigs. Widely scattered showers possible across northern MA
and interior CT during the afternoon. S-SW wind 10-20 kt with
sea-breezes along the coast.

Monday Night...Moderate confidence.

VFR with localized MVFR possible. S-SW wind 10 kt.

KBOS TAF...High confidence in TAF.

Diurnal VFR cu this afternoon with a low probability of a spot
shower. Opt to leave out of the TAF due to low confidence in
this occurring. ESE wind will continue this afternoon, becoming
S around 00z. Overnight, light WSW wind, will have another sea-
breeze on Monday between 14z and 16z.

KBDL TAF...Moderate confidence in TAF.

Diurnal VFR cu this afternoon, CIGs are between 4-5 thousand
feet through 00z and 02z, during this time a brief light shower
is possible. Wind becomes calm overnight, potentially promoting
areas of fog, confidence in how widespread or dense remains low.
VFR again on Monday with CIGs 4-6 thousand feet. Showers
possible Monday afternoon.

Outlook /Monday Night through Friday/...

Monday Night: VFR. Slight chance SHRA.

Tuesday: VFR. Breezy. Slight chance SHRA.

Tuesday Night: MVFR/IFR conditions possible. Breezy. Chance
SHRA.

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

Wednesday Night: Mainly VFR, with local IFR possible. Breezy.
Chance SHRA.

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

Thursday Night: VFR. Breezy. Slight chance SHRA.

Friday: VFR. Breezy.

&&

.MARINE...
Forecaster Confidence Levels:

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

Tonight through Monday night....

Southwest winds along the southern waters and southeast winds
along the eastern waters through this evening, wind speeds are
less than 15 knots and then winds are light from the southwest
overnight. Seas are generally 2 to 4 feet, far outer waters
seas may approach 5 feet. Have continued a Small Craft Advisory
through this evening for the southern outer waters.

Southwest winds increase on Monday with gusts under 20 knots.
Seas are 4 feet or less. There will be a sea-breeze, with a
southeast wind for the near shore waters from Cape Ann to Cape
Cod Bay. Showers possible Monday afternoon and evening for
northeast waters. Seas building to 5 feet for the southern
waters Monday night. Forecasters tonight will need to evaluate
the need for a new Small Craft Advisory.

Outlook /Monday Night through Friday/...

Monday Night: Winds less than 25 kt. Slight chance of rain
showers.

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

Tuesday Night through Wednesday: Winds less than 25 kt. Seas
locally approaching 5 ft. Chance of rain showers.

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

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

Thursday Night: Winds less than 25 kt. Local rough seas. Slight
chance of rain showers.

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

&&

.BOX WATCHES/WARNINGS/ADVISORIES...
CT...None.
MA...None.
RI...None.
MARINE...Small Craft Advisory until 8 PM EDT this evening for ANZ254-
     255.

&&

$$

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