FXUS61 KBOX 111716

Area Forecast Discussion
National Weather Service Boston/Norton MA
1216 PM EST Mon Dec 11 2023

Multifaceted storm with heavy rain and potentially damaging
wind gusts will impact southern New England this morning. Behind
this departing system, the week ahead looks dry. Expecting a
cool-down mid week, before warming up once again towards next



1 PM Update...

Precipitation has come to an end across southern New England as
ceilings lift and begin to break up from southwest to northeast.
Gusty, drying, northwest flow continues to build to ~25kt over
the next few hours.

9 AM Update...

System appears to be moving slightly faster than forecast with
the front now exiting the Cape; in turn, taking the damaging
wind threat with it. Given the wind threat has diminished, the
High Wind Warning has been terminated  at the top of the hour.
Additionally, storm warnings across the waters are being
converted to small crafts and will continue to be converted
through the morning as the front moves east of the outer waters.

Minor river flooding is occurring or will begin occurring today
across many areas. We will continue to monitor the threat over
the next 12-24 hours to add warnings where necessary.

Rapid clearing will occur behind the departing system between
15-18Z, with breaks of sunshine expected with the exception
being the high terrain which may retain cloud cover into the

249 AM Update...

Latest guidance suite and observations indicated a quicker
timing for the eastward progression of a cold front across
southern New England. Latest observations already had this front
past Nashua NH, Worcester MA and Willimantic CT. Based on
current timing, that would place this front along the east coast
of MA towards 7 AM, then finally offshore towards mid morning.
This is about 5 hours faster than the previous forecast.

This is important to several aspects of the forecast, mainly
due to the wind shift and reducing the duration of heavy
rainfall. This may also limit the magnitude of wind speeds,
which were just starting to gust up around 45 mph in spots as of
this writing. While still expecting at least some snowfall
across the east slopes of the Berkshires, the quicker timing
should limit amounts. Thinking snowfall amounts will remain
below 3 inches. Hence no need for a Winter Weather Advisory

The latest NationalBlend appeared to have a rather good handle
on this timing. Thus used it for the basis for the forecast this
morning. Expecting nearly steady to falling temperatures through
the day, meaning early high temperatures. Will address the
hydrology and coastal flooding concerns in their own section

Wind continue wind headlines as they currently are. Will
reevaluate and possibly make changes with the 4 AM forecast.


High pressure then builds east towards the Mid Atlantic coast
tonight into Tuesday. Expecting dry weather and mainly clear
skies with a diminishing west wind. Near normal temperatures
during this portion of the forecast.


Key Points:
 - Mainly dry weather expected
 - Near to below normal temperatures give way to another warmup
   by next weekend

Upper level pattern should feature a broad trough over much of
eastern US through midweek, but with a lack of downstream
blocking, the synoptic pattern remains progressive and this
trough will exit to Maritimes. This will allow for a pattern
change late this week as an upper ridge takes hold and brings
yet another warmup into next weekend. This pattern also favors
dry weather overall with a large high pressure nearby to our
south and west.


Forecast Confidence Levels:

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

18Z Update...

High confidence in trends, moderate confidence in timing of VFR

Through tonight...

Conditions will continue to improve across
all terminals this afternoon and early evening with a transition
from MVFR to VFR over the next two to three hours. Anticipating
all terminals will be VFR by 22Z. Gusty NW flow maintains
20-25kt through sunset before diminishing slightly to 15kt
overnight. Gusts will be slowest to diminish over the high

Tomorrow and tomorrow night... High Confidence

VFR through the period as winds become more SW around daybreak
Tuesday. Winds generally 10kt with gusts to 15kt. Tranquil
conditions and SW flow continue overnight.

KBOS Terminal...High confidence in trends. Moderate confidence
in timing.

KBDL Terminal...High confidence.

Outlook /Tuesday Night through Friday/...

Tuesday through Wednesday: VFR. Breezy.

Wednesday Night: VFR. Windy with areas of gusts up to 30 kt.

Thursday: VFR. Windy with local gusts up to 30 kt.

Thursday Night through Friday: VFR. Breezy.


Forecaster Confidence Levels:

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

based on the latest observed trends, confined the Storm Warning
to the outer coastal waters, as well as Nantucket Sound. Gale
Warnings elsewhere, but only through 7 AM for Boston Harbor and
Mass Bay, as well as Narragansett Bay and Block Island Sound.
Remaining Gale Warnings continue into mid morning. Further
headline changes expected with later forecasts today as winds
continue to diminish slowly.

249 AM Update...

A cold front was quickly approaching the waters this morning.
Winds were just starting to ramp up across the waters. Starting
to think we may not quite get to storm-force winds, but the
threat remains. Winds were southerly at 88 kt at 2,000-2,500 ft
above ground, and it would not take much more mixing to bring
some of this down to the surface. Will maintain the Storm
Warnings for now, and continue to monitor. May be able to
downgrade to Gale Warnings later this morning.

Moderate to heavy rainfall will reduce visibility at times this
morning. An abrupt and significant shift in winds is expected
as this cold front crosses the waters. Seas gradually diminish
through the day, but seas will still be rough on the waters into

Outlook /Tuesday Night through Friday/...

Tuesday: Winds less than 25 kt. Areas of rough seas.

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

Wednesday: Low risk for Small Craft Advisory winds with gusts
up to 30 kt. Seas up to 5 ft.

Wednesday Night: Strong winds with gusts up to 35 kt. Seas up
to 5 ft.

Thursday: Moderate risk for Small Craft Advisory winds with
local gusts up to 30 kt. Local rough seas.

Thursday Night: Low risk for Small Craft Advisory winds with
gusts up to 25 kt. Seas locally approaching 5 ft.

Friday: Moderate risk for Small Craft Advisory winds with gusts
up to 25 kt. Areas of seas approaching 5 ft.


MARINE...Small Craft Advisory until 7 PM EST this evening for ANZ230-
     Small Craft Advisory until 3 PM EST Tuesday for ANZ232>235-237.
     Small Craft Advisory until 7 PM EST Tuesday for ANZ250-254>256.
     Small Craft Advisory until 5 AM EST Tuesday for ANZ251.