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Area forecast discussion 
National Weather Service Taunton Massachusetts
104 PM EDT Thursday Oct 23 2014

Synopsis...
a powerful early season coastal storm will pass southeast of
Nantucket this evening. Rain will become more showery this
afternoon but strong winds will continue to affect eastern New
England. Showers continue to diminish Friday as the storm slowly
pulls away from New England. Showers possible again Saturday
evening and overnight as low pressure moves into southern Quebec. Dry
and seasonably cool weather returns Sunday into early next week.

&&

Near term /through tonight/...
* conditions slowly improve through tonight *

Regional radar mosaic shows main band of heavy rain associated
with middle level deformation zone has shifted into eastern New York and
central New England early this afternoon.

In its wake scattered showers were rotating westward around upper
low S of New England where airmass has become marginally unstable.
High-res models have a good handle on this and have a few hundred
j/kg of ml/MUCAPE this afternoon...which will help more activity
develop through late afternoon...especially around Cape Cod and
islands. Not looking for any severe weather...but higher cores
could produce strong wind gusts as well as brief downpours.

Activity will diminish this evening as low passes southeast of New
England. Models point to a secondary surge of wind as winds shift
more to N/NW...especially near coast. As a result we will keep
Wind Advisory posted...though strongest winds appear more likely
to occur until 7 or 8 PM.

Cyclonic flow and leftover moisture will keep clouds locked in
tonight along with few showers. Lows will drop back into 40s/50s.

&&

Short term /Friday through Friday night/...
gradual improvement Friday as low slowly pulls toward Maritimes. May
see few leftover showers especially Thursday morning and closer to
coast. Cross sections indicate Little Hope for significant
clearing until Friday night...so clouds will dominate until then...
although some breaks of sun are certainly possible in western New
England.

Stayed close to blend of model guidance for temperatures...which gives
highs in 50s Thursday and back into 40s Thursday night.

&&

Long term /Saturday through Wednesday/...
* showers possible again Saturday as low pressure moves into Quebec
* mainly dry and seasonable weather early next week

Overall the 12z model suite is in fairly good agreement through the
long term. There are some discrepancies in the mesoscale details but
otherwise they are in good agreement. After the coastal storm
currently affecting the region moves away from southern New
England...the weather starts to dry out and become more seasonable.
There are a couple of cold fronts expected to move through the
region and each of these may bring some showers with them.



Saturday...another upper level trough moves over the northeast with
low pressure moving through southern Quebec and into the Maritimes.
The models Don/T show a whole lot of moisture or a big wind shift
with this front but we could see some showers. The GFS has a
stronger low level jet than the European model (ecmwf) which could enhance the amount
of rainfall but there is still much to be seen with this system.

Sunday through Tuesday...high pressure starts to build into southern
New England bringing dry and seasonable weather. Temperatures begin
to climb and may warm to well above normal by Tuesday.

Wednesday...low pressure moving through the Great Lakes and into
Quebec may bring a cold front through southern New England. Another
chance of some showers possible with this front but plenty of
uncertainty.

&&

Aviation /18z Thursday through Tuesday/...
forecaster confidence levels...

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

Short term /through Thursday night/...moderate confidence.

Not much change in conditions through early tonight with MVFR/IFR
ceilings...although VFR ceilings more likely around Cape Cod and islands
and points offshore. Should see return to IFR ceilings near coast
tonight with MVFR ceilings farther inland. Scattered showers/isolated
thunder mainly around Cape Cod and islands with MVFR cigs/vsbys.

Gusty north/northwest winds to 35kt especially near coast through 00z.

Slow improvement Thursday with MVFR/IFR ceilings in morning giving way to
VFR ceilings by afternoon from west to east. VFR Thursday night as clearing works
into New England.

Kbos...moderate confidence. Lower-end MVFR ceilings most likely
through this evening before ceilings drop to IFR tonight.

Kbdl...high confidence.

Outlook...Saturday through Monday...

Moderate confidence. VFR. Low probability of scattered showers
Saturday.

&&

Marine...
forecaster confidence levels...

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

Short term /through Friday night/...

* conditions gradually improve *

Coastal storm passes southeast of Nantucket this evening and to Maritimes
Thursday and Thursday night. This will bring gradually diminishing winds and
especially seas...which will take a couple of days to subside.

Maintained gale warnings on most waters through tonight as we
expect another surge of north gales later this afternoon and
evening...before winds diminish tonight and Thursday.

Scattered showers and isolated storms through this evening...
especially around Cape Cod and islands. Otherwise few leftover
showers Thursday morning.

Outlook...Saturday through Monday...

Saturday and Sunday...moderate confidence. After a brief lull...seas
and winds will increase ahead of a cold front. Small craft
advisories will likely be needed for at least a portion of the
waters.

Monday...moderate confidence. Winds and seas diminish as high
pressure builds over the waters.

&&

Tides/coastal flooding...
last night/S high tide yielded a storm surge of 1.5 feet to 2.0 feet.
This combined with large wave action resulted in widespread minor
coastal flooding/inundation from Plymouth County northward. Both
etss and estofs are about 50% too low with their surge values when
compared to current observations. Thus have increased guidance by 50
percent.

We are now ramping up to the late morning/midday high tide cycle.
Prior storm surge forecast looks good and have not changed. At
0945 EDT the surge was running at 2 feet at bos...about twice as
high as the guidance. Waves just offshore running 16 to 18 feet.
The north-northeast gradient appears to be retightening for a period as
advertised by short term models and think waves will hold at
these heights or possibly even increase another foot or two before
subsiding this evening. The astronomical tide is about a half foot
higher today than last night and will allow wave activity to runup
somewhat further along the beach. Hence...the impact could be a
little higher than what was experienced last night. Also...we have
the issue of this becoming a fairly long duration event with
continued erosion of the dune slopes along Sandy Beach areas. Will
keep the coastal Flood Advisory in place for Salisbury to Cape Ann
and Hull to Plymouth. Our greatest concern continues to be beach
erosion in the Salisbury and Plum Island area.

There may be some splashover and minor beach erosion for the high
tide tonight but do not believe it will reach an advisory level.

&&

Box watches/warnings/advisories...
CT...Wind Advisory until 11 PM EDT this evening for ctz004.
Massachusetts...Wind Advisory until 11 PM EDT this evening for maz005>007-
012>021.
Coastal Flood Advisory until 2 PM EDT this afternoon for
maz007-019.
New Hampshire...Wind Advisory until 11 PM EDT this evening for nhz012.
Rhode Island...Wind Advisory until 11 PM EDT this evening for riz001>007.
Marine...Small Craft Advisory until 11 PM EDT this evening for
anz231>234-236-254-255.
Gale Warning until 11 PM EDT this evening for anz230-250-251-
256.
Gale Warning until 10 PM EDT this evening for anz235-237.

&&

$$
Synopsis...jwd
near term...jwd
short term...jwd
long term...rlg
aviation...jwd
marine...jwd
tides/coastal flooding...Thompson

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