708
FXUS61 KBOX 180535
AFDBOX

Area Forecast Discussion
National Weather Service Boston/Norton MA
135 AM EDT Wed Sep 18 2024

.SYNOPSIS...
High pressure continues to support warm and mainly dry weather
through Wednesday afternoon. We`ll have our next chance for
measurable precipitation late Weds afternoon/evening. Chances
should be confined to Cape Cod and the Islands. Otherwise,
mainly dry with mostly cloudy conditions and blustery NE winds
through this weekend.

&&

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

130AM Update

Widespread dense fog across most of southeastern MA, Cape Cod,
and the south coast with vsby ranging from 1/4SM to 1SM. Dense
fog advisory in effect through 10AM. Fog should lift by mid to
late morning.


Previous Discussion

Upper level ridging coupled with offshore surface
high pressure will continue to keep weather quiet tonight. Mid
to upper level moisture wrapping around the slow moving low
pressure across the SE CONUS brings higher clouds into southern
New England this afternoon and tonight. Around the Cape and
Islands lower clouds are beginning to fill back in and move
closer to shore. Light southerly flow is expected tonight with
increasing moisture in a shallow surface layer. Under an upper
ridge, there is still dry air just above the strong temperature
inversion. This will support development of low stratus and
patchy fog tonight into early tomorrow morning. There is some
uncertainty in the extent of the lower cloud, with higher
confidence for low stratus and patchy fog south of the Mass Pike
across SE MA and the south coast. Some areas of the south coast
and Cape/Island may also see light drizzle early tomorrow
morning. Also areas of the CT River Valley may see patchy fog in
the early morning hours. Low temperatures will be slightly
warmer than previous nights in the low 50s to low 60s.

&&

.SHORT TERM /6 AM THIS MORNING THROUGH 6 PM THURSDAY/...
Wednesday:

Similar to Tuesday morning, expect a gradual improvement in fog/low
stratus through mid-morning. The Cape/Islands will likely be one of
the slower regions to improve, potentially even past mid-morning.
Surface high pressure sits offshore bringing easterly flow onshore
in the afternoon. Temperatures range in the low 70s to low 80s.

Wednesday Night:

Shower chances increase into the late afternoon/evening hours. There
are still differences in the timing of the showers among model
guidance, but overall there is a general consensus on shower chances
increasing across the south coast and Cape/Island in this timeframe
as moisture increases. Low clouds and scattered showers continue
overnight with the higher chances across the south coast, Cape, SE
MA. Overall, not looking like a high coverage rain event with a more
scattered mode for showers.

&&

.LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/...
Latest guidance suite continued to show at least broad agreement
on the overall theme of the forecast, but agreement with the
details still remained elusive. Tried to trend the forecast with
this update towards the consensus solution, without making large
changes just yet.

Overall, expecting a mid level trough to be nearby late this
week into early this weekend. This will provide our next chance
for some showers. It has been some time since we have had
measurable rainfall for most of southern New England, so we have
capacity to handle quite a bit of rainfall. Have the greatest
confidence in rainfall across the Cape and islands, with lower
confidence towards the NW. This uncertainty stems from the
combination of how strong a ridge of high pressure will be
across our region, and how close a low pressure can approach
from the south. At this time, thinking it is most likely this
low pressure travels just SE of the 40N/70W benchmark.

Another aspect which will need to be monitored closely with this
low pressure is coastal flooding. Astronomical tides are rather
high later this week. A slow-moving low pressure with persistent
winds with at least some onshore component for the south coast
of New England may result in pockets of coastal flooding issues
late this week.

High pressure should then build into our region from the N this
weekend into early next week, leading to more dry weather.

Temperatures anticipated to trend below normal by this weekend,
and continue into early next week.

&&

.AVIATION /06Z WEDNESDAY THROUGH SUNDAY/...
Forecast Confidence Levels:

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

Through 12Z...High Confidence

LIFR ceilings and vsbys across southeastern MA and RI this
morning with areas of dense fog. Fog may reach as far north as
BOS on the east coast and may also creep up the CT River Valley
as the evening progresses. VFR at BAF/BDL deteriorating to IFR
after 08Z. VFR at BAF/ORH.

Today...High Confidence in trends, moderate on timing

LIFR ceilings/vsbys improve to VFR between 15-17Z as fog slowly
mixes out after sunrise. Winds becoming easterly by the
afternoon with shower chances increasing over the south coast by
00Z.

Tonight...High Confidence in trends

Winds become more northeasterly overnight with showers
overspreading southeastern MA, RI, and The Cape/Islands. This
will be accompanied by IFR/MVFR ceilings that will persist into
Thursday.

Tomorrow...High Confidence

Showers over southeastern MA, RI, and The Cape/Islands will
result in MVFR/IFR conditions with ceilings near 1000 feet.
Northeast winds 5 to 10 knots.

KBOS TAF...Moderate Confidence

VFR conditions may deteriorate to MVFR/LIFR as fog and low
stratus creeps up the east coast. Added a TEMPO group for 1SM
vsbys between 10 and 13Z. VFR thereafter with winds becoming
onshore by the afternoon. MVFR ceilings return overnight with
shower chances increasing Thursday morning.

KBDL TAF...High confidence in TAF.

Outlook /Thursday Night through Sunday/...

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

Thursday Night: VFR. Breezy. Slight chance SHRA.

Friday: Mainly VFR, with local MVFR possible. Windy with local
gusts up to 30 kt. Slight chance SHRA.

Friday Night: Mainly VFR, with areas MVFR possible. Breezy.
Slight chance SHRA.

Saturday: Mainly VFR, with areas MVFR possible. Windy with
local gusts up to 30 kt.

Saturday Night through Sunday: VFR. Breezy.

&&

.MARINE...
Forecaster Confidence Levels:

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

Marine

Today and Tonight

High pressure just east of the coastal waters continues to
support calm/tranquil boating conditions through at least
Wednesday morning. Winds remain modest at speeds less than 10 kt
knots out of the south/southeast. Seas range from 0 to 1 feet in
the near- shore zones and 2 to 3 feet over the outer waters.

Wednesday and Wednesday Night

Low-pressure approaching from the south will result in rising
seas over the south coastal waters. Seas rise to 5 to 6 feet
over the coastal waters south of MVY and Block Island Wednesday
evening. A Small Craft Advisory has been issued Wednesday
evening through Thursday morning.

Outlook /Thursday Night through Sunday/...

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

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

Friday: Moderate risk for Small Craft Advisory winds with gusts
up to 30 kt. Rough seas up to 8 ft. Slight chance of rain
showers.

Friday Night: Moderate risk for Small Craft Advisory winds with
gusts up to 25 kt. Rough seas up to 8 ft. Slight chance of rain
showers.

Saturday: Moderate risk for Small Craft Advisory winds with
local gusts up to 30 kt. Rough seas up to 9 ft. Slight chance
of rain showers.

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

Sunday: Low risk for Small Craft Advisory winds with gusts up
to 25 kt. Rough seas up to 9 ft.

&&

.BOX WATCHES/WARNINGS/ADVISORIES...
CT...None.
MA...Dense Fog Advisory until 10 AM EDT this morning for MAZ013-
     016>024.
RI...Dense Fog Advisory until 10 AM EDT this morning for RIZ001>004-
     006-008.
MARINE...Small Craft Advisory from 5 PM this afternoon to 8 AM EDT
     Thursday for ANZ254>256.

&&

$$

SYNOPSIS...BW/Mensch
NEAR TERM...Mensch
SHORT TERM...Mensch
LONG TERM...BW
AVIATION...BW/Mensch
MARINE...BW/Mensch