Gale Warning 51, NWS Boston/Norton, MA

800 
WHUS71 KBOX 150345
MWWBOX

URGENT - MARINE WEATHER MESSAGE
National Weather Service Boston/Norton MA
1045 PM EST Mon Dec 14 2020

ANZ231-250-251-254-151200-
/O.CON.KBOX.GL.W.0051.201215T0600Z-201215T1500Z/
Cape Cod Bay-
Coastal waters east of Ipswich Bay and the Stellwagen Bank
National Marine Sanctuary-Massachusetts Bay and Ipswich Bay-
Coastal waters from Provincetown MA to Chatham MA to Nantucket MA
out 20 nm-
1045 PM EST Mon Dec 14 2020

...GALE WARNING REMAINS IN EFFECT UNTIL 10 AM EST TUESDAY...

* WHAT...Northwest winds 15 to 25 kt with gusts up to 35 kt and 
  seas 6 to 9 feet expected.

* WHERE...Cape Cod Bay, Coastal waters east of Ipswich Bay and 
  the Stellwagen Bank National Marine Sanctuary, Massachusetts 
  Bay and Ipswich Bay and Coastal waters from Provincetown MA to 
  Chatham MA to Nantucket MA out 20 nm.

* WHEN...Until 10 AM EST Tuesday.

* IMPACTS...Strong winds will cause hazardous seas which could 
  capsize or damage vessels and reduce visibility.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Mariners should alter plans to avoid these hazardous conditions.
Remain in port, seek safe harbor, alter course, and/or secure the
vessel for severe conditions.

&&

$$

ANZ255-256-151200-
/O.CON.KBOX.SC.Y.0143.000000T0000Z-201216T0600Z/
Coastal Waters extending out to 25 nm South of Marthas Vineyard
and Nantucket-
Coastal Waters from Montauk NY to Marthas Vineyard extending out
to 20 nm South of Block Island-
1045 PM EST Mon Dec 14 2020

...SMALL CRAFT ADVISORY REMAINS IN EFFECT UNTIL 1 AM EST
WEDNESDAY...

* WHAT...Northwest winds 15 to 25 kt with gusts up to 30 kt and 
  seas 5 to 8 feet.

* WHERE...In Massachusetts coastal waters, Coastal Waters 
  extending out to 25 nm South of Marthas Vineyard and 
  Nantucket. In Rhode Island coastal waters, Coastal Waters from 
  Montauk NY to Marthas Vineyard extending out to 20 nm South of 
  Block Island.

* WHEN...Until 1 AM EST Wednesday.

* IMPACTS...Conditions will be hazardous to small craft.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Inexperienced mariners, especially those operating smaller
vessels, should avoid navigating in hazardous conditions.

&&

$$

ANZ232>235-237-151200-
/O.CON.KBOX.SC.Y.0143.000000T0000Z-201216T0000Z/
Nantucket Sound-Vineyard Sound-Buzzards Bay-Rhode Island Sound-
Block Island Sound-
1045 PM EST Mon Dec 14 2020

...SMALL CRAFT ADVISORY REMAINS IN EFFECT UNTIL 7 PM EST
TUESDAY...

* WHAT...Northwest winds 10 to 20 kt with gusts up to 30 kt and 
  seas 3 to 5 feet.

* WHERE...In Massachusetts coastal waters, Nantucket Sound, 
  Vineyard Sound and Buzzards Bay. In Rhode Island coastal 
  waters, Block Island Sound and Rhode Island Sound.

* WHEN...Until 7 PM EST Tuesday.

* IMPACTS...Conditions will be hazardous to small craft.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Inexperienced mariners, especially those operating smaller
vessels, should avoid navigating in hazardous conditions.

&&

$$

ANZ230-236-151200-
/O.CON.KBOX.SC.Y.0143.000000T0000Z-201215T1800Z/
Boston Harbor-Narragansett Bay-
1045 PM EST Mon Dec 14 2020

...SMALL CRAFT ADVISORY REMAINS IN EFFECT UNTIL 1 PM EST
TUESDAY...

* WHAT...Northwest winds 10 to 15 kt with gusts up to 30 kt and 
  waves around 2 feet.

* WHERE...In Massachusetts coastal waters, Boston Harbor. In 
  Rhode Island coastal waters, Narragansett Bay.

* WHEN...Until 1 PM EST Tuesday.

* IMPACTS...Conditions will be hazardous to small craft.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Inexperienced mariners, especially those operating smaller
vessels, should avoid navigating in hazardous conditions.

&&

$$

314 
WHUS71 KBOX 150814
MWWBOX

URGENT - MARINE WEATHER MESSAGE
National Weather Service Boston/Norton MA
314 AM EST Tue Dec 15 2020

ANZ254-151615-
/O.CON.KBOX.GL.W.0051.000000T0000Z-201215T1500Z/
/O.NEW.KBOX.GL.A.0033.201216T2100Z-201217T0000Z/
Coastal waters from Provincetown MA to Chatham MA to Nantucket MA
out 20 nm-
314 AM EST Tue Dec 15 2020

...GALE WARNING REMAINS IN EFFECT UNTIL 10 AM EST THIS MORNING...
...GALE WATCH IN EFFECT FROM WEDNESDAY AFTERNOON THROUGH
WEDNESDAY EVENING...

* WHAT...For the Gale Warning, northwest winds 20 to 25 kt with 
  gusts up to 35 kt and seas 7 to 10 feet. For the Gale Watch, 
  northeast winds 10 to 15 kt and seas around 3 feet possible.

* WHERE...Coastal waters from Provincetown MA to Chatham MA to 
  Nantucket MA out 20 nm.

* WHEN...For the Gale Warning, until 10 AM EST this morning. For 
  the Gale Watch, from Wednesday afternoon through Wednesday 
  evening.

* IMPACTS...Strong winds will cause hazardous seas which could 
  capsize or damage vessels and reduce visibility.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Mariners should alter plans to avoid these hazardous conditions.
Remain in port, seek safe harbor, alter course, and/or secure the
vessel for severe conditions.

&&

$$

ANZ231-250-251-151500-
/O.CON.KBOX.GL.W.0051.000000T0000Z-201215T1500Z/
Cape Cod Bay-
Coastal waters east of Ipswich Bay and the Stellwagen Bank
National Marine Sanctuary-Massachusetts Bay and Ipswich Bay-
314 AM EST Tue Dec 15 2020

...GALE WARNING REMAINS IN EFFECT UNTIL 10 AM EST THIS MORNING...

* WHAT...Northwest winds 15 to 25 kt with gusts up to 35 kt and 
  seas 6 to 9 feet expected.

* WHERE...Cape Cod Bay, Coastal waters east of Ipswich Bay and 
  the Stellwagen Bank National Marine Sanctuary, Massachusetts 
  Bay and Ipswich Bay and Coastal waters from Provincetown MA to 
  Chatham MA to Nantucket MA out 20 nm.

* WHEN...Until 10 AM EST Tuesday.

* IMPACTS...Strong winds will cause hazardous seas which could 
  capsize or damage vessels and reduce visibility.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Mariners should alter plans to avoid these hazardous conditions.
Remain in port, seek safe harbor, alter course, and/or secure the
vessel for severe conditions.

&&

$$

ANZ255-256-151615-
/O.CON.KBOX.SC.Y.0143.000000T0000Z-201216T0600Z/
/O.NEW.KBOX.GL.A.0033.201216T2100Z-201217T0000Z/
Coastal Waters extending out to 25 nm South of Marthas Vineyard
and Nantucket-
Coastal Waters from Montauk NY to Marthas Vineyard extending out
to 20 nm South of Block Island-
314 AM EST Tue Dec 15 2020

...SMALL CRAFT ADVISORY REMAINS IN EFFECT UNTIL 1 AM EST
WEDNESDAY...
...GALE WATCH IN EFFECT FROM WEDNESDAY AFTERNOON THROUGH
WEDNESDAY EVENING...

* WHAT...For the Small Craft Advisory, northwest winds 15 to 25 
  kt with gusts up to 30 kt and seas 5 to 8 feet. For the Gale 
  Watch, east winds 15 to 20 kt with gusts up to 25 kt and seas 
  2 to 4 feet possible.

* WHERE...In Massachusetts coastal waters, Coastal Waters 
  extending out to 25 nm South of Marthas Vineyard and 
  Nantucket. In Rhode Island coastal waters, Coastal Waters from 
  Montauk NY to Marthas Vineyard extending out to 20 nm South of 
  Block Island.

* WHEN...For the Small Craft Advisory, until 1 AM EST Wednesday. 
  For the Gale Watch, from Wednesday afternoon through Wednesday 
  evening.

* IMPACTS...Strong winds can cause hazardous seas which could
  capsize or damage vessels and reduce visibility.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Mariners should consider altering plans to avoid possible
hazardous conditions.  Remain in port, seek safe harbor, alter
course, and/or secure the vessel for severe wind and seas.

&&

$$

ANZ232>235-237-151615-
/O.CON.KBOX.SC.Y.0143.000000T0000Z-201216T0000Z/
/O.NEW.KBOX.GL.A.0033.201216T2100Z-201217T0000Z/
Nantucket Sound-Vineyard Sound-Buzzards Bay-Rhode Island Sound-
Block Island Sound-
314 AM EST Tue Dec 15 2020

...SMALL CRAFT ADVISORY REMAINS IN EFFECT UNTIL 7 PM EST THIS
EVENING...
...GALE WATCH IN EFFECT FROM WEDNESDAY AFTERNOON THROUGH
WEDNESDAY EVENING...

* WHAT...For the Small Craft Advisory, northwest winds 10 to 20 
  kt with gusts up to 30 kt and seas 3 to 5 feet. For the Gale 
  Watch, northeast winds 10 to 15 kt with gusts up to 25 kt and 
  seas 1 to 3 feet possible.

* WHERE...In Massachusetts coastal waters, Nantucket Sound, 
  Vineyard Sound and Buzzards Bay. In Rhode Island coastal 
  waters, Rhode Island Sound and Block Island Sound.

* WHEN...For the Small Craft Advisory, until 7 PM EST this 
  evening. For the Gale Watch, from Wednesday afternoon through 
  Wednesday evening.

* IMPACTS...Strong winds can cause hazardous seas which could
  capsize or damage vessels and reduce visibility.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Mariners should consider altering plans to avoid possible
hazardous conditions.  Remain in port, seek safe harbor, alter
course, and/or secure the vessel for severe wind and seas.

&&

$$

ANZ230-236-151615-
/O.CON.KBOX.SC.Y.0143.000000T0000Z-201215T1800Z/
Boston Harbor-Narragansett Bay-
314 AM EST Tue Dec 15 2020

...SMALL CRAFT ADVISORY REMAINS IN EFFECT UNTIL 1 PM EST THIS
AFTERNOON...

* WHAT...Northwest winds 10 to 15 kt with gusts up to 30 kt and 
  waves around 2 feet.

* WHERE...In Massachusetts coastal waters, Boston Harbor. In 
  Rhode Island coastal waters, Narragansett Bay.

* WHEN...Until 1 PM EST Tuesday.

* IMPACTS...Conditions will be hazardous to small craft.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Inexperienced mariners, especially those operating smaller
vessels, should avoid navigating in hazardous conditions.

&&

$$

804 
WHUS71 KBOX 151508
MWWBOX

URGENT - MARINE WEATHER MESSAGE
National Weather Service Boston/Norton MA
1008 AM EST Tue Dec 15 2020

ANZ231-152315-
/O.EXP.KBOX.GL.W.0051.000000T0000Z-201215T1500Z/
/O.EXB.KBOX.GL.A.0033.201216T2100Z-201218T0600Z/
Cape Cod Bay-
1008 AM EST Tue Dec 15 2020

...GALE WATCH IN EFFECT FROM WEDNESDAY AFTERNOON THROUGH LATE
THURSDAY NIGHT...
...GALE WARNING HAS EXPIRED...

* WHAT...Northeast winds 20 to 30 kt with gusts up to 35 kt and 
  seas 6 to 9 feet possible.

* WHERE...Cape Cod Bay.

* WHEN...From Wednesday afternoon through late Thursday night.

* IMPACTS...Strong winds can cause hazardous seas which could
  capsize or damage vessels and reduce visibility.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Mariners should consider altering plans to avoid possible
hazardous conditions.  Remain in port, seek safe harbor, alter
course, and/or secure the vessel for severe wind and seas.

&&

$$

ANZ250-251-152315-
/O.EXP.KBOX.GL.W.0051.000000T0000Z-201215T1500Z/
/O.EXB.KBOX.GL.A.0033.201216T2100Z-201218T0600Z/
Coastal waters east of Ipswich Bay and the Stellwagen Bank
National Marine Sanctuary-Massachusetts Bay and Ipswich Bay-
1008 AM EST Tue Dec 15 2020

...GALE WATCH IN EFFECT FROM WEDNESDAY AFTERNOON THROUGH LATE
THURSDAY NIGHT...
...GALE WARNING HAS EXPIRED...

* WHAT...Northeast winds 20 to 30 kt with gusts up to 40 kt and 
  seas 6 to 11 feet possible.

* WHERE...Coastal waters east of Ipswich Bay and the Stellwagen 
  Bank National Marine Sanctuary and Massachusetts Bay and 
  Ipswich Bay.

* WHEN...From Wednesday afternoon through late Thursday night.

* IMPACTS...Strong winds can cause hazardous seas which could 
  capsize or damage vessels and reduce visibility.


PRECAUTIONARY/PREPAREDNESS ACTIONS...

Mariners should consider altering plans to avoid possible
hazardous conditions.  Remain in port, seek safe harbor, alter
course, and/or secure the vessel for severe wind and seas.

&&

$$

ANZ254-152315-
/O.EXP.KBOX.GL.W.0051.000000T0000Z-201215T1500Z/
/O.EXT.KBOX.GL.A.0033.201216T2100Z-201218T0600Z/
Coastal waters from Provincetown MA to Chatham MA to Nantucket MA
out 20 nm-
1008 AM EST Tue Dec 15 2020

...GALE WATCH NOW IN EFFECT FROM WEDNESDAY AFTERNOON THROUGH LATE
THURSDAY NIGHT...
...GALE WARNING HAS EXPIRED...

* WHAT...Northeast winds 20 to 30 kt with gusts up to 40 kt and 
  seas 9 to 14 feet possible.

* WHERE...Coastal waters from Provincetown MA to Chatham MA to 
  Nantucket MA out 20 nm.

* WHEN...From Wednesday afternoon through late Thursday night.

* IMPACTS...Strong winds can cause hazardous seas which could 
  capsize or damage vessels and reduce visibility.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Mariners should consider altering plans to avoid possible
hazardous conditions.  Remain in port, seek safe harbor, alter
course, and/or secure the vessel for severe wind and seas.

&&

$$

ANZ255-256-152315-
/O.CON.KBOX.SC.Y.0143.000000T0000Z-201216T0600Z/
/O.EXT.KBOX.GL.A.0033.201216T2100Z-201218T0600Z/
Coastal Waters extending out to 25 nm South of Marthas Vineyard
and Nantucket-
Coastal Waters from Montauk NY to Marthas Vineyard extending out
to 20 nm South of Block Island-
1008 AM EST Tue Dec 15 2020

...SMALL CRAFT ADVISORY REMAINS IN EFFECT UNTIL 1 AM EST
WEDNESDAY...
...GALE WATCH NOW IN EFFECT FROM WEDNESDAY AFTERNOON THROUGH LATE
THURSDAY NIGHT...

* WHAT...For the Small Craft Advisory, northwest winds 15 to 25 
  kt with gusts up to 30 kt and seas 5 to 8 feet. For the Gale 
  Watch, east winds 15 to 20 kt with gusts up to 25 kt and seas 
  2 to 4 feet possible.

* WHERE...In Massachusetts coastal waters, Coastal Waters 
  extending out to 25 nm South of Marthas Vineyard and 
  Nantucket. In Rhode Island coastal waters, Coastal Waters from 
  Montauk NY to Marthas Vineyard extending out to 20 nm South of 
  Block Island.

* WHEN...For the Small Craft Advisory, until 1 AM EST Wednesday. 
  For the Gale Watch, from Wednesday afternoon through late 
  Thursday night.

* IMPACTS...Strong winds can cause hazardous seas which could 
  capsize or damage vessels and reduce visibility.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Mariners should consider altering plans to avoid possible
hazardous conditions.  Remain in port, seek safe harbor, alter
course, and/or secure the vessel for severe wind and seas.

&&

$$

ANZ232>235-237-152315-
/O.CON.KBOX.SC.Y.0143.000000T0000Z-201216T0000Z/
/O.EXT.KBOX.GL.A.0033.201216T2100Z-201218T0600Z/
Nantucket Sound-Vineyard Sound-Buzzards Bay-Rhode Island Sound-
Block Island Sound-
1008 AM EST Tue Dec 15 2020

...SMALL CRAFT ADVISORY REMAINS IN EFFECT UNTIL 7 PM EST THIS
EVENING...
...GALE WATCH NOW IN EFFECT FROM WEDNESDAY AFTERNOON THROUGH LATE
THURSDAY NIGHT...

* WHAT...For the Small Craft Advisory, northwest winds 10 to 20 
  kt with gusts up to 30 kt and seas 3 to 5 feet. For the Gale 
  Watch, northeast winds 10 to 15 kt with gusts up to 25 kt and 
  seas 1 to 3 feet possible.

* WHERE...In Massachusetts coastal waters, Nantucket Sound, 
  Vineyard Sound and Buzzards Bay. In Rhode Island coastal 
  waters, Rhode Island Sound and Block Island Sound.

* WHEN...For the Small Craft Advisory, until 7 PM EST this 
  evening. For the Gale Watch, from Wednesday afternoon through 
  late Thursday night.

* IMPACTS...Strong winds can cause hazardous seas which could 
  capsize or damage vessels and reduce visibility.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Mariners should consider altering plans to avoid possible
hazardous conditions.  Remain in port, seek safe harbor, alter
course, and/or secure the vessel for severe wind and seas.

&&

$$

ANZ230-236-151800-
/O.CON.KBOX.SC.Y.0143.000000T0000Z-201215T1800Z/
Boston Harbor-Narragansett Bay-
1008 AM EST Tue Dec 15 2020

...SMALL CRAFT ADVISORY REMAINS IN EFFECT UNTIL 1 PM EST THIS
AFTERNOON...

* WHAT...Northwest winds 10 to 15 kt with gusts up to 30 kt and 
  waves around 2 feet.

* WHERE...In Massachusetts coastal waters, Boston Harbor. In 
  Rhode Island coastal waters, Narragansett Bay.

* WHEN...Until 1 PM EST Tuesday.

* IMPACTS...Conditions will be hazardous to small craft.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Inexperienced mariners, especially those operating smaller
vessels, should avoid navigating in hazardous conditions.

&&

$$

Area Forecast Discussion
National Weather Service Boston/Norton MA
1256 PM EST Mon Dec 14 2020

.SYNOPSIS...
Weak low pressure tracks south of New England today, bringing a
period of snow, sleet and rain to the region late this morning and
afternoon. Drier but much colder air overspreads the region tonight
behind the departing low. Cold high pressure provides dry weather
Tuesday and Wednesday. Then a coastal storm may bring heavy snow,
strong winds and coastal flooding to the region Wednesday night and
Thursday. High pressure brings dry weather Friday and possibly
lingering into next weekend. Cold temperatures at the end of the
week likely moderate over the weekend.

&&

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

1 PM update...

Seeing widespread precip falling across southern New England
this afternoon, having become all snow for locations from
Hartford to Worcester to Lawrence and north. Elsewhere
temperatures have been slow to cool as much as expected which is
keeping rain for much of RI and the coastal plain. Temperatures
were raised a few degrees this afternoon which should even
further keep any snow from accumulating. Not expecting any
commuting issues this evening.

Previous Discussion...

*** A period of Snow late Morning into Afternoon with Minor
Accumulations ***

Today...

Southern and northern stream short waves approach the region today.
Southern stream short wave and its weak surface cyclone will track
southeast of the 40N/70W benchmark late today, along with its best
forcing for ascent just offshore of RI/MA coast. However northern
stream short wave will be able to back the mid level flow just
enough to advect southern stream moisture into CT/RI/MA. This
combined with some enhanced Q/G forcing from its RRQ 150 kt upper
level jet streak across Southern New England, will be sufficient to
generate a period of light to moderate precip. Good model agreement
on qpf ranging from 0.10 to 0.25 inches across the area, with up to
0.50 along the immediate south coast and Islands. Thus steadiest
precip will be across CT-RI and south of the Massachusetts Turnpike
and especially the south coast including Cape Cod and the Islands.

Start time for precip looks to be about 14z/15z CT into western-
central MA to 16z-18z RI and Eastern MA. Per model soundings,
evaporative cooling initially supports snow all areas except south
coast where ptype will be rain. Then some brief warming in the 800-
900 mb layer occurs a few hours after the onset, which likely yields
a mix of snow and sleet. Then the column cools with height falls and
snow/sleet mix likely changing back to all snow. It is during this
time period 18z-22z when mixed precip changes over to all snow, that
it could snow moderate to perhaps briefly heavy, as model time
sections indicate modest lift in the snow growth region. Although
model 2 meter temps struggle to fall into the low 30s. Thus snow
likely struggles to accumulate on paved surfaces especially main
roads. Although secondary roads and any untreated surfaces could
become snow covered. Along the south coast precip will be steadier
and somewhat heavier, however warmer boundary layer and surface
temps to overcome, and therefore delaying rain changing over to
snow.

So given light qpf (0.10 to 0.25 inches, except up to 0.50 south
coast), mixed ptype and marginal surface temps, we are only
forecasting a coating to an inch for most of CT/RI and south of the
Mass Pike, with a few spots possibly approaching 2 inches in the
hilly terrain of Northern CT into Northwest RI. Again, higher
accumulations on non paved surfaces, with less on main roadways.
Hence more of a decorative snow with little impacts other than
briefly lowering vsby and perhaps secondary roads becoming snow
covered for a time. Less snow for Cape Cod and the Islands where
mainly rain will fall before briefly ending as snow late this
afternoon/early evening.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM TUESDAY/...
345 AM update...

Tonight...

Any lingering rain/snow over Cape Cod and the Islands early this
evening, will quickly exit offshore with dry weather overspreading
the entire region. However turning much colder behind departing
northern stream short wave. 850 mb temps go from -3C at 00z to -12C
by 12z Tue. This will result in lows temps falling into the 20s, but
gusty NW winds up to 35 mph over Cape Cod and the Islands will
result in wind chills in the teens. Could be some lake effect clouds
and flurries spilling into western CT/MA. Otherwise dry weather
prevails.

Tuesday...

Dry but cold NW flow with 850 mb temps from -8C to -12C across the
region. So despite mostly sunny conditions, these temps aloft will
only support highs in the low to mid 30s, upper 20s high terrain.
Gusty NW winds will make it feel even colder with wind chills in the
20s.

&&

.LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/...
345 AM Update:

 * Winter storm becoming more likely Wed night/Thu

Main concern for the extended forecast continues to be the
potential winter storm which should affect SNE Wed night into
Thu and may bring heavy snow, strong winds along coast, minor to
perhaps moderate coastal flooding, and hazardous marine
conditions.

00z models and their ensembles have shown good consistency with
their previous runs and remain in two general camps: GFS which
keeps system farther offshore (outside 40/70 benchmark) and
shows heavier snow near South Coast, Cape Cod, and Islands and
international models (ECMWF, Canadian, and UKMET) which bring
system near 40/70 benchmark and show a more significant
snowstorm for most of SNE.

Given we are 3 days out, model error in track can be quite
large, so it's still too early to try and nail down specifics
such as precise snowfall amounts and where mesoscale banding
will set up. However, we can look at larger scale pattern to
help determine which solution (benchmark or offshore) merits
more weight.

System passing through region today will intensity rapidly over
Maritimes over next few days. This becomes critical to the track
of the winter storm since it affects flow downstream from us,
mainly by helping strengthen confluent flow aloft which in turn
prevents ridging from helping to slow down and maintain
strength of upper trough. This should result in opening up of
500 mb low, which is shown by just about all models with
exception of 00z NAM which is an outlier and does not fit this
expectation.

Upstream, we also do not see much upper level ridging across
northern Rockies which would be needed to help deepen trough
over eastern states. This also allows system to open up as it
passes our region instead of closing off or maintaining its
strength.

What all this means is there is less of a chance that coastal
low comes much closer to coast than 40/70 and it won't have a
chance to deepen rapidly as it passes our area, thus limiting
impacts such as widespread heavy snow and strong winds. In
addition, models show strongest 850 wind field and moisture
convergence across NJ and Long Island before both weaken with
time as they reach SNE.

All of these factors argue against a "blockbuster storm" for the
entire region but there are other considerations that certainly
favor heavy snow including presence of deep southern stream
moisture and a cold airmass in place which should yield high
snow to water ratios (fluffy snow). There is likely to be a
tight snowfall gradient somewhere in northern MA (thinking Route
2 right now) but this could shift north or even south in future
model runs. It does look like best chance for seeing 6-12" of
snow is along and south of the Mass Pike with 2-6" north of
there, but again, this may shift in later forecasts. Then
there's the issue of low level temperatures which may cause
p-type issues or prevent accumulations on the outer Cape and
Nantucket.

Confidence is not high enough to consider Winter Storm Watches
just yet - there is enough uncertainty based upon all of the
above factors to play this more conservatively since we are
still 72+ hours out.

Otherwise, we're in for a cold week as northern stream
dominates.

&&

.AVIATION /18Z MONDAY THROUGH SATURDAY/...
Forecaster Confidence Levels...

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

18Z update...Moderate confidence this afternoon due to timing
of lower conditions. High confidence tonight and Tue.

Light snow continues for interior TAF sites, with a rain/snow
mix or all rain at coastal sites including Cape Cod/the Islands,
which should transition to all snow before ending later this
afternoon and early this evening. Snow accumulations only a
coating are expected. Less accumulation on paved surfaces given
temps in the low to mid 30s.

Any lingering rain/snow over Cape Cod and Islands at 00z quickly
moves offshore with all terminals becoming VFR. Gusty NW winds
develop especially high terrain and Cape Cod/Islands. VFR and
dry but gusty NW winds becoming N Tue. Winds diminish Tue night.
VFR.

KBOS TAF...Moderate confidence in the TAF.

KBDL TAF...Moderate confidence in the TAF.

Outlook /Tuesday Night through Friday/...

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

Tuesday Night: VFR. Breezy.

Wednesday: VFR. Breezy. Slight chance SN.

Wednesday Night: Mainly IFR, with areas MVFR possible. Windy
with gusts up to 35 kt. SN.

Thursday: Mainly VFR, with local IFR possible. Windy with gusts
up to 35 kt. Chance SN.

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

Friday: VFR. Breezy.

&&

.MARINE...
345 AM Update:

*** Gale Watch Tonight For Strong NW Winds ***

Today...high confidence.

Weak low pressure tracks south of 40N/70W. Rain and snow limit vsby
this afternoon.

Tonight...high confidence.

Behind departing offshore low, much colder air overspreads the
waters on gusty NW winds up to 35 kt. Thus Gale Watch as been
issued. Early evening rain and snow quickly exits offshore with dry
weather remainder of the night.

Tuesday...high confidence.

Sub 980 mb low over Newfoundland and 1030+ mb high over Ontario will
result in strong NW winds across the waters. Possible gale force
early Tue, then slowly easing later in the day as high pressure
advects closer to New England.

Outlook /Tuesday Night through Friday/...

Tuesday: Moderate risk for Small Craft Advisory winds with
gusts up to 30 kt. Rough seas up to 11 ft.

Tuesday Night: Winds less than 25 kt. Local rough seas.

Wednesday: Winds less than 25 kt. Seas locally approaching
5 ft. Slight chance of snow.

Wednesday Night: Low risk for gale force winds with gusts up to
35 kt. Rough seas up to 13 ft. Snow, rain. Areas of visibility
1 nm or less.

Thursday: Strong winds with gusts up to 35 kt. Rough seas up to
14 ft. Chance of rain, chance of snow. Local visibility 1 nm or
less.

Thursday Night: Moderate risk for Small Craft Advisory winds
with gusts up to 30 kt. Rough seas up to 13 ft. Slight chance
of rain showers, slight chance of snow showers.

Friday: Low risk for Small Craft Advisory winds with gusts up
to 25 kt. Rough seas up to 10 ft.

&&

.TIDES/COASTAL FLOODING...
Today and Tuesday:

Very high astronomical high tides will result in splashover/minor
coastal flooding along the eastern MA coast during the late morning
high tide cycles today and Tue. Fortunately, we are not dealing
with built up seas or a strong onshore component because astro
high tide in Boston is 11.9 feet both days. Nonetheless, that is
quite high and will allow for some splashover/minor coastal
flooding particularly today with pressure falls from an offshore
low pressure system.

Thursday:

Coastal low passing SE of Nantucket is expected to produce a
storm surge of around 2 feet with the early afternoon high tide
(11.3 FT MLLW at Boston and 4.0 FT MLLW at Nantucket Harbor),
which is expected to produce minor coastal flooding along E MA
coast. System is not forecast to deepen rapidly so N/NE winds
should not be strong enough (35-40kt) or seas have enough time
to build significantly (10-15 ft) to produce more significant
impacts, although strength of high pressure to our north could
help winds/seas get higher than currently expected.

Since we are still a few days away we still need to monitor
potential for a change in the track of the low as well as its
strength. A stronger system, or one that tracks closer to the
region, could produce lower-end moderate coastal flooding. That
would be a worst case scenario which is unlikely right now.

We do need to be concerned for minor beach erosion, which could
have more of an impact in more vulnerable locations such as Plum
Island.

&&

.BOX WATCHES/WARNINGS/ADVISORIES...
CT...None.
MA...None.
RI...None.
MARINE...Gale Watch from midnight EST tonight through Tuesday morning
     for ANZ231-232-250-251-254.
     Gale Watch from 11 PM EST this evening through late tonight
     for ANZ233>235-237-255-256.

&&

SYNOPSIS...Nocera/JWD
NEAR TERM...Nocera/BW/JWD
SHORT TERM...Nocera
LONG TERM...JWD
AVIATION...Nocera/BW
MARINE...Nocera/JWD
TIDES/COASTAL FLOODING...

Hazardous Weather Outlook
National Weather Service Boston/Norton MA
442 AM EST Mon Dec 14 2020

CTZ002>004-MAZ002>024-026-NHZ011-012-015-RIZ001>008-150945-
Hartford CT-Tolland CT-Windham CT-Western Franklin MA-
Eastern Franklin MA-Northern Worcester MA-Central Middlesex MA-
Western Essex MA-Eastern Essex MA-Western Hampshire MA-
Western Hampden MA-Eastern Hampshire MA-Eastern Hampden MA-
Southern Worcester MA-Western Norfolk MA-Southeast Middlesex MA-
Suffolk MA-Eastern Norfolk MA-Northern Bristol MA-
Western Plymouth MA-Eastern Plymouth MA-Southern Bristol MA-
Southern Plymouth MA-Barnstable MA-Dukes MA-Nantucket MA-
Northern Middlesex MA-Cheshire-Eastern Hillsborough-
Western And Central Hillsborough-Northwest Providence RI-
Southeast Providence RI-Western Kent RI-Eastern Kent RI-Bristol RI-
Washington RI-Newport RI-Block Island RI-
442 AM EST Mon Dec 14 2020

This Hazardous Weather Outlook is for northern Connecticut, all of
Massachusetts east of Berkshire County, New Hampshire,
southern New Hampshire, and Rhode Island.

.DAY ONE...Today and tonight.

Hazardous weather is not expected at this time.

.DAYS TWO THROUGH SEVEN...Tuesday through Sunday.

The potential exists for a winter storm late Wednesday into Thursday
which could bring heavy snow to much of the area, strong winds along
the coast, and coastal flooding and beach erosion to eastern
Massachusetts.

.SPOTTER INFORMATION STATEMENT...

Spotter activation is not expected at this time.

ANZ233>235-237-255-256-150945-
Vineyard Sound-Buzzards Bay-Rhode Island Sound-Block Island Sound-
Coastal Waters extending out to 25 nm South of Marthas Vineyard and
Nantucket-
Coastal Waters from Montauk NY to Marthas Vineyard extending out to
20 nm South of Block Island-
442 AM EST Mon Dec 14 2020

...GALE WATCH IN EFFECT FROM THIS EVENING THROUGH LATE TONIGHT...

This Hazardous Weather Outlook is for Massachusetts coastal waters
and Rhode Island coastal waters.

.DAY ONE...Today and tonight.

Please listen to NOAA Weather Radio or go to weather.gov on the
Internet for more information about the following hazards.

   Gale Watch.

.DAYS TWO THROUGH SEVEN...Tuesday through Sunday.

Gale to perhaps storm force wind gusts are possible late Wednesday
into Thursday as a strong coastal storm tracks southeast of New
England.

.SPOTTER INFORMATION STATEMENT...

Spotter activation is not expected at this time.

ANZ231-232-250-251-254-150945-
Cape Cod Bay-Nantucket Sound-
Coastal waters east of Ipswich Bay and the Stellwagen Bank National
Marine Sanctuary-Massachusetts Bay and Ipswich Bay-
Coastal waters from Provincetown MA to Chatham MA to Nantucket MA
out 20 nm-
442 AM EST Mon Dec 14 2020

...GALE WATCH IN EFFECT FROM LATE TONIGHT THROUGH TUESDAY MORNING...

This Hazardous Weather Outlook is for Massachusetts coastal waters.

.DAY ONE...Today and tonight.

Please listen to NOAA Weather Radio or go to weather.gov on the
Internet for more information about the following hazards.

   Gale Watch.

.DAYS TWO THROUGH SEVEN...Tuesday through Sunday.

Please listen to NOAA Weather Radio or go to weather.gov on the
Internet for more information about the following hazards.

   Gale Watch.

.SPOTTER INFORMATION STATEMENT...

Spotter activation is not expected at this time.

ANZ230-236-150945-
Boston Harbor-Narragansett Bay-
442 AM EST Mon Dec 14 2020

This Hazardous Weather Outlook is for Massachusetts coastal waters
and Rhode Island coastal waters.

.DAY ONE...Today and tonight.

No hazardous weather is expected at this time.

.DAYS TWO THROUGH SEVEN...Tuesday through Sunday.

Gale force wind gusts are possible late Wednesday into Thursday as a
strong coastal storm tracks southeast of New England.

.SPOTTER INFORMATION STATEMENT...

Spotter activation is not expected at this time.

For more information on upcoming hazardous weather, please see the
Area Forecast Discussion on our webpage for the latest forecast
thinking. There is also our Enhanced Hazardous Weather Outlook at
www.weather.gov/box/ehwo

For the latest updates...please visit our webpage at
www.weather.gov/boston

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@NWSBoston