Area Forecast Discussion
Issued by NWS Boston, MA

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FXUS61 KBOX 030018

Area Forecast Discussion
National Weather Service Taunton MA
718 PM EST Fri Dec 2 2016

Cooler temperatures are expected as we head into the weekend.
Other than scattered light snow showers or flurries over the
northern and western higher terrain areas, it should remain
mainly dry through most of the weekend. A few brief snow or rain
showers are possible Sunday night into early Monday. Otherwise,
high pressure will provide dry weather Monday afternoon through
Tuesday morning. Low pressure moving out of the Ohio valley to the
mid Atlantic states may bring some mixed precipitation as far
north as southern New England late Tuesday night and Wednesday,
but timing and track remain uncertain. The potential for another
period of unsettled weather exists for later in the next workweek.



00Z Update...

Only minor adjustments to forecast early this evening. Continuing
to expect periods of cloudiness as short wave moves thru the area
tonight. Radar showing isolated rain showers in the coastal waters
and moving ESE, will continue to monitor but at this time only
affecting the marine zones. Temperatures look on track.

Previous discussion follows...

Latest guidance continues to advertise a potent mid level
shortwave passing overhead tonight, and not too far ahead of the
primary longwave trough. This should produce, or at least
maintain, some clouds over much of southern New England. There
could be some snow showers as well across portions of northwest
MA. Little to no accumulation is expected. The higher elevations
along the east slopes of the Berkshires are most at risk for
accumulating snow.

Seasonable temperatures, with a persistent, and sometimes gusty,
west wind.


Saturday...Looks to be dry with mostly sunny, at at least away
from the northern MA border and the east coast. Still expecting
the surface wind become more northerly during the day. This will
most likely mean ocean-effect clouds, and perhaps some showers,
too. Any showers would mainly impact the outer Cape, but really
not expecting much of anything to develop.

Winds will again be fairly gusty, reaching 20 to 25 mph during
much of the day.

Saturday Night...Lower clouds and spotty ocean-effect rain
showers may continue across outer Cape Cod. Not expecting much in
the way of QPF, as it`s a low risk. Otherwise, expect mainly dry
conditions elsewhere across the region.

Winds will be gusty, up to 25-30 kt across the higher inland
terrain, as well as along the coast. Near seasonable temperatures.



* Temperatures running a bit below seasonal normals through at
  least Tuesday
* Low pressure moving out of the Ohio Valley/mid-Atlantic states may
  push some mixed precipitation into the region Tuesday night and
  Wednesday, but confidence remains low
* Low confidence regarding timing of unsettled weather next Thu/Fri.

Sunday...High confidence.

Lower clouds and spotty ocean effect rain showers may initially
continue into Sunday morning across outer Cape Cod as colder air
moves across the milder waters on strong N-NW winds. Otherwise high
pressure builds into the area with dry conditions and mostly clear
skies. Could see wind gusts to 25 kt initially along the shoreline,
but as high builds in and pressure gradient relaxes, winds will
lower.  Temperatures will be a few degrees cooler than normal, with
highs in the 30s to low 40s.

Sunday night through Monday...Moderate confidence.

Continue to expect a band of clouds moving thru the area from a weak
mid level short wave that pushes into/thru the region Sun night into
Monday. Not much moisture to work with this feature as it pertains
to our area, though 12Z ECMWF does shows some light QPF amounts
during Sunday night/Monday morning, accompanied by a very weak
surface low. GFS solution is drier...and with W/NW flow still
looking to be in place for Monday...thinking that a mainly dry, low
QPF solution looks reasonable. Will go with mainly a slight
chance pop for a few showers or snow showers.

Monday night...Moderate confidence.

Dry conditions and mostly clear skies prevail Monday night with
surface high pressure centered over southern Quebec...and upper
level ridging...being the main influence on our weather.

Tuesday and Wednesday...Low confidence.

Models continue to differ regarding how much precipitation makes its
way into southern New England during this timeframe. Low pressure
system to our SW tries to bring moisture into our area. Elongated
precip shield lies to the S and W of the region as high pressure
shifts E of the region Tuesday and Tuesday night. Big question will
be the timing as the high exits, if it does. Models still show the
potential for 2 surface low pressure centers developing, one moving
thru the southern Great Lakes Region and another moving off the
Carolina or Mid-Atlantic coastline.

Uncertainty exists on whether we end up with minimal QPF between
these 2 systems. Model and ensemble solution spread lending to lower
than average confidence. Will continue to lean toward a model blend
at this point due to the remaining uncertainty and timing, with
chance pops late Tuesday as well as Wednesday. Precip could be a
wintry mix of light snow/rain.

Thursday and Friday...Low confidence.

While models show a deep mid level trof digging into the central and
eastern US, there are significant differences in timing/placement.
This in turn makes a difference in surface features, along with
issues with how the sensible weather evolves. ECMWF shows a
surface low approaching from the SW, while 12Z GFS shows a
weaker solution for our area. Overall, low confidence continues.
Will continue chance POPs at this time.


Forecaster Confidence Levels...

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

Short Term /through Saturday Night/...

High confidence. Mainly VFR across southern New England through
this period, with a couple of exceptions. The first exception is pockets
of MVFR cigs that are anticipated across the higher terrain
towards the Berkshires through tonight. The second would be the
low risk for MVFR cigs across the outer Cape, and towards the
Berkshires, Saturday afternoon into Saturday night.

Gusty west winds gradually become gusty northwest winds for Saturday
morning. Expecting northwest winds to continue through Saturday

Scattered snow showers tonight over the Berkshires could locally
lower the visibility to 5 or 6 miles.

KBOS TAF...High confidence in overall TAF. VFR. There may be
periods where west winds gust to around 20 to 25 knots tonight.
NW wind gusts 25 to 30 kt anticipated for Saturday.

KBDL TAF...High confidence in overall TAF.

Outlook /Sunday through Wednesday/...

Sunday...High confidence. Mainly VFR. May see some spotty light SHRA
Sunday morning across outer Cape Cod. NW wind gusts up to 25 kt,
early along higher terrain and near the coastline, diminishing
in the morning.

Sunday night and Monday...Moderate confidence. May see patchy MVFR
conditions in spotty -SHRA/-SHSN Sunday night into Monday morning,
then should be mainly VFR by Monday afternoon.

Monday night...Moderate confidence. VFR.

Tuesday and Wednesday...Moderate confidence for overall trends,
lower on exact timing. Mainly VFR Tuesday morning. May see MVFR
CIGS/VSBYS move into central and western areas Tuesday afternoon in
mainly -RA, but may see mixed precipitation interior. MVFR
CIGS/VSBYS possible Tue night into Wed with chance of light


Forecaster Confidence Levels.

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

Short Term /through Saturday Night/...

Moderate confidence for this period. Isolated rain showers within
souther coastal waters this evening. Gusty winds will persist
from the west tonight, and northwest Saturday. While there will be
times where winds briefly diminish below 25 kt, it is very
difficult to identify precisely when, and for how long the lulls
persist, before the gusty conditions return. Thus, will keep Small
Craft Advisories up for most waters through Saturday night.

Lower confidence on the timing of Small Craft Advisories in Boston
Harbor and Narragansett Bay.

Will need to monitor the trends through this weekend.

Outlook /Sunday through Wednesday/...Moderate confidence.

Sunday and Monday...Expect winds and seas to diminish below small
craft criteria during Sunday, then should remain below small craft
Sunday night and Monday.

Monday night and Tuesday...Winds and seas remain below small craft
criteria for most of the waters. N-NE winds gusting up to 25 kt and
seas may build to 4-5 feet during Tuesday night along the southern
coastal waters.

Wednesday...Winds/seas may reach small craft criteria, especially
along the southern coastal waters.


MARINE...Small Craft Advisory until 6 AM EST Sunday for ANZ231>235-237-
     Small Craft Advisory until midnight EST Saturday night for
     Small Craft Advisory until 1 PM EST Saturday for ANZ236.


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