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Area forecast discussion 
National Weather Service Taunton Massachusetts
715 am EST sun Jan 25 2015

Synopsis...

Chilly and blustery conditions expected today. A major and
potentially historic winter storm will affect the region Monday
night into Tuesday night...travel may become impossible and life
threatening. Drier weather follows Wednesday into early
Thursday...but will have to watch for another chance of snow by
the end of the work week.

&&

Near term /until 6 PM this evening/...

715 am update...

Band of middle level cloudiness covered our western zones along with
just a few snow flurries. This was associated with a cold front
that was crossing the region. Should see clouds scatter out later
this morning and afternoon behind the front.

Blustery and cold conditions...with the
expectation that daytime high temperatures are likely to occur about middle
day...with gradual cooling into the evening hours. Moderate mixing
support wind gusts 20-25 knots /25-30 miles per hour/ through the day.
Therefore...with temperatures in the upper 20s to middle 30s...wind chills are
likely dip back into the teens and 20s.

&&

Short term /6 PM this evening through 6 PM Monday/...
tonight...
weak nose of high pressure will crest across the region...associated
with a cold airmass. This cold blocking high pressure will be the
feature needed for the early week storm. The weakened pressure
gradient could allow for some radiational cooling...but increasing
cloudiness from the SW are likely to limit ability to radiate. In
any case...the increase in snowpack across the region should still
yield a cool night. Suspect some areas do dip below 0f in northwest
valleys...while the rest of the area falls back into the teens.

Monday...
high pressure slides itself into place to the north during the morning.
Given it/S placement and location...and the fact that it is
associated with dewpoints starting in the low teens and single digits
Monday morning...like the slower timing of precipitation displayed by the
NAM/ECMWF. Therefore...only bring categorical probability of precipitation into the mix
by the evening timeframe Monday...suggesting that it will take some
time for snows to begin reaching the ground during the day on Monday.
Otherwise...expect only light accums by before Monday night mainly
across CT...SW Massachusetts and S Rhode Island. MOS highs likely a bit too warm given
the indication of wet bulb processes...so went a bit cooler. Winds
begin to pick up toward evening as well...but strongest winds are
not expected until later in the forecast.

&&

Long term /Monday night through Saturday/...

Highlights...

* major to potentially historic winter storm Monday night into Tuesday night
* blizzard watch eastern Massachusetts/Rhode Island
* 1 to 2 feet of snow for many areas - locally higher amts possible
* damaging winds possible coast especially cape/islands - gusts 60 to 70 miles per hour
* significant coastal flooding possible along the eastern Massachusetts coast

Details...

This is pretty much a text book case for a major winter
storm/blizzard in southern New England. Potent shortwave dives
southeast closes off south of Long Island as low pressure bombs out
and tracks up the New England coast. The highly amplified pattern
will allow for a slow moving/long duration storm. In
addition...high pressure across eastern Canada will supply plenty of
cold air for the storm to work with so ptype will probably only be a
concern for the far southeast New England coast.

We are now quite confident that this will be a major winter storm
and it has the potential to become historic for some locations.
Will break down the various hazards in the next view paragraphs.

1) heavy snow/blizzard conditions/wind and ptype

The middle level low/S are closing off just south of southern New
England Monday night and Tuesday. That will probably put US near
ground zero for the heaviest snow. The models are in very good
agreement in showing 1 to 2 feet of snow for much of the region. Of
course there may be areas that exceed 2 feet where localized banding
sets up...but its too early to worry about that. Very strong
pressure gradient with 1035 mb high over eastern Canada and bombing
surface low will likely result in strong to damaging northeast wind
gusts of 45 to 60 miles per hour across eastern MA/RI. Gusts between 60 to 70
miles per hour expected across the cape/islands!

Will issue a blizzard watch for much of eastern Massachusetts/Rhode Island for 1 to 2
feet of snow and 40 to 60 miles per hour wind gusts. This looks to be a
serious winter storm and travel will likely become extremely
difficult to impossible with near zero visibility. Considerable
blowing and drifting snow also expected.

Across central and western Massachusetts/northern CT have issued a Winter Storm
Watch for 12 to 24 inches of snow. Its possible we may have to
upgrade some of that region to a blizzard watch/warning...but was
uncertain how much wind would mix down across that region and its
still a late 4th and 5th period event. We are also leaning towards
the western envelope of solutions at this time led the consistent
European model (ecmwf). If the storm trends east a bit...we may be overdone with our
snow accumulations across our western zones so something for later
shifts to watch.

The cape and islands present the most challenging forecast.
Depending on exact track of the storm...portions of the region may
mix with or change to rain for a time. If colder solutions verify
there will be blizzard conditions...but if it ends up warmer could
be a fair amount of rain. Therefore...will hoist a winter storm
and high wind watch. In fact...we like going with the high wind
watch here for the potential of 60 to 70 miles per hour winds. This may
combine with any wet snow to cause downed trees and power outages.

2) timing:

The worst of the storm looks to occur Monday night into Tuesday
afternoon. At least snow showers will likely linger Tuesday night
as the system becomes vertically stacked and very slow to depart the
region. Dry weather should finally work into the region sometime
Wednesday morning.

3) narrow swath of damaging wet snow

Will have to watch for a narrow swath of heavy wet snow along the
southeast New England coast. This could be problematic in terms of
downed trees and power outages...especially given the strong winds.
It may be a small area just northwest of the rain/snow line...but
may have a significant impact.

Wednesday through Saturday...

While the storm comes to an end early Wednesday morning and the cleanup
begins...we may be dealing with another winter storm later Thursday or
Friday.

&&

Aviation /12z Sunday through Thursday/...
forecaster confidence levels...

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

Short term /through Monday/...

Through Monday...high confidence.
Mainly VFR. A few low clouds dissipate early today giving way to
mainly middle and high clouds which will clear by tonight.
Precipitation and lower categories will likely take until very
late in the day on Monday.

Kbos taf...high confidence in taf.

Kbdl taf...high confidence in taf.

Outlook /Monday night through Thursday/...

Monday night and Tuesday...moderate to high confidence. Heavy snow
and strong winds along the coast will result in IFR to LIFR
conditions. Blowing and drifting snow is also expected. Northeast
wind gusts of 45 to 60 knots expected along the coast.

Wednesday...moderate confidence. Conditions to improve to VFR from
west to east...but timing in question. North-northwest wind gusts up to 25-30
knots possible early along the coast.

Thursday...low confidence. Timing of low pressure and next chance of
snow later Thursday or perhaps Friday.

&&

Marine...
forecaster confidence levels...

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

Short term /through Monday/...high confidence.

Winds and seas remain elevated today as a cold front crosses the
waters. Therefore...small craft advisories remain in place through
this evening for all waters...and into the overnight for the ocean
waters. Conditions improve briefly early Monday ahead of an
approaching storm for Monday night into Tuesday.

Outlook /Monday night through Thursday/...

***life threatening storm for mariners with seas building to over 25
feet and winds gusts to 60 knots Monday night into tuesday***

Monday night through Tuesday night...moderate to high confidence.
Rapidly intensifying low pressure moving across the waters will
combine with high pressure across eastern New England. This will
result in northeast wind gusts increasing to 50 to 60 knots and
building seas to over 25 feet across our eastern waters. Storm
watches posted and low probability that we may need hurricane force
wind warnings! This is dangerous and life threatening storm and
mariners should return to port by Monday afternoon.

Wednesday...moderate confidence. Should see at least leftover north-northwest
wind gusts up to small craft criteria during Wednesday...then should
diminish Wednesday night.

Thursday...low confidence. Winds should remain below small craft
criteria. Seas may linger at around 5 feet.

&&

Tides/coastal flooding...

A significant coastal flood event is possible along the eastern Massachusetts
coast during the early Tuesday morning and late Tuesday afternoon
high tide cycle. Northeast wind gusts between 45 and 60 knots will
seas building to over 25 feet across our eastern outer waters.
Astronomical high tide is 10.5 feet in Boston on Tuesday at 430 am.
The potential for a 3+ foot storm surge may result in moderate to
isolated pockets of major coastal flooding. Another high tide will
have to watch closely occurs late Tuesday afternoon/early evening
since seas will be built up. In addition...significant beach
erosion is possible.

A coastal Flood Watch has been issued for eastern Massachusetts including Cape
Cod and Nantucket.

&&

Box watches/warnings/advisories...
CT...Winter Storm Watch from Monday evening through late Tuesday
night for ctz002>004.
Massachusetts...blizzard watch from Monday evening through late Tuesday night
for maz005>007-013>021.
Coastal Flood Watch from late Monday night through Tuesday
evening for maz007-015-016-019-022-024.
Winter Storm Watch from Monday evening through late Tuesday
night for maz002>004-008>012-022>024-026.
High wind watch from Monday evening through late Tuesday night
for maz022>024.
Rhode Island...blizzard watch from Monday evening through late Tuesday night
for riz001>008.
Marine...storm watch from Monday evening through Tuesday evening for
anz230>237-250-251-254>256.
Small Craft Advisory until 7 PM EST this evening for
anz230>234-236-251.
Small Craft Advisory until 1 am EST Monday for anz235-237.
Small Craft Advisory until 7 am EST Monday for anz250-254>256.

&&

$$
Synopsis...Frank/doody
near term...Frank/doody
short term...doody
long term...Frank
aviation...doody/Frank
marine...doody/Frank
tides/coastal flooding...Frank

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