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Area forecast discussion 
National Weather Service Taunton Massachusetts
1120 PM EDT Wed Oct 26 2016

high pressure will push across the region tonight. Strong low
pressure will push across the region late Thursday into Friday,
which will bring a period of wintry weather well inland at the
start, rain heavy at times elsewhere along with gusty winds at the
coast. Another low passes to our north but swings a cold front
through New England over the weekend. High pressure brings dry
weather to the region Sunday through Tuesday. One more cold front
moves through the region midweek.


Near term /until 6 am Thursday morning/...

11 PM update...

Mid and high clouds have pushed NE across central and western
areas through 03z as seen on infrared satellite imagery and observation over
the last few hours. Temps have already fallen to the mid and upper
20s across the mass portion of the CT valley into central mass,
and the lower-mid 30s away from the immediate coast. Dewpts have
risen to between 20 and 25 degrees across most areas, though a
bit higher along the S coast. Light north-northwest winds continue as the
high pres ridge builds slowly east out of East New York state.

While high clouds have pushed in, they are thin enough to allow
temps to continue to fall with good radiational cooling. Patchy
low clouds and spotty showers have moved across Outer Cape cod
over the last couple of hours. Noting increasing area of showers
across eastern Cape Cod Bay into the mid and Outer Cape as well as
into eastern Nantucket Sound as seen on latest kbox 88d radar

Have adjusted cloud cover to increase coverage, as well as
temps/dewpts to bring conditions current as well as incorporating
into near term trends.

Previous discussion...

Most areas will freeze away from the immediate coast. Have issued
a freeze warning for those areas that are still active in the
frost/freeze program. In addition, because of light winds and
increasing low level moisture, widespread frost is expected so
have issued a frost advisory for the coastal zones that are still
active, including Cape Cod. For Cape Cod, the main areas affected
will be the upper cape, away from the ocean effect clouds/showers.
Block Island, Martha's Vineyard, and Nantucket will likely be too
warm for frost even so have kept them out of any headlines.

Expect light north winds as the ridge builds in. This is a more
favorable wind direction for ocean effect showers affecting the
Outer Cape and even farther west towards the mid cape. Cold air
aloft over the relatively warm ocean will provide enough
instability for clouds certainly, as well as a few ocean effect
snow showers. Given this would be the first instance of the
season, do not anticipate any accumulation but residents may see
some showers or flurries overnight.


Short term /6 am Thursday morning through Thursday night/...

Snow potential...
high pressure over Quebec is pushed to the east as low pressure
in the Great Lakes slowly moves eastward. This approaching low
pressure system will shift winds to the east- southeast allowing
for increasing moisture into the region. Coupled with that are the
frigid temperatures both at the ground and aloft, making for an
area conducive to some snow to start out. This low pressure system
remains dominant through most of the day, giving way to a
secondary low that forms somewhere over the tri-state region and
moves up over southern New England Thursday night. The timing of
this interaction and the transition of power to the secondary low
will be a big player in determining duration and extent of snow.
Expect snow to move into the SW zones shortly after sunrise and
proceed to the NE quickly. Expect snow to remain north and west of
I-95, and likely most of it will be north and west of I-495 as
well. Little to no accumulation is expected, particularly at the
lower elevations. Elevations above 1500 ft may see a light
dusting. However, the timing of the onset of snow and the fact
that it will be the first widespread snow of the season, expect
some impacts to the morning commute as we all get our snow tires
under US, so to speak.

Rain potential...
while east of the I-95 corridor will remain all rain, expect all
areas to change over to rain around noon. Precipitable waters are
rather high for this time of year, around 150% of normal, so this
rain will be heavy at times. Heaviest precip is expected to be
during the overnight period, particularly as the dry slot
approaches, instability increases somewhat, and the low level jet
increases as the warm sector moves over southeastern New England.
Expect anywhere from about three-quarters of an inch of rain to
just over an inch of widespread rainfall. A few areas may see more
than this, some may see less. It depends on how convective the
rain gets during the overnight hours. This shouldn't cause any
widespread flooding issues. Mostly just poor drainage and urban

Wind potential...
low level jet increases Thursday night as it moves across Rhode
Island and southeast Massachusetts. This coupled with the rain and
potential convection may result in strong, gusty winds mixing down
to the surface. Wind Advisory criteria may be hit on the cape and
islands, as indicated by BUFKIT model soundings. Think there is a
decent chance of that occurring but am not quite confident enough
to put up a winds advisory. Will give the mid shift another chance
to look at it before hoisting a headline.

while Thursday morning will start out rather cold, temperatures
will rebound throughout the day. While temps will not be much
warmer than they have been today, the real recovery will be during
the overnight. Not expecting widespread freezing temperatures
Thursday night, with temperatures warming in some areas overnight.
As the warm sector moves over Rhode Island and southeast MA, expect temperatures to
increase through the 40s and possibly into the lower 50s early
Friday morning.


Long term /Friday through Wednesday/...

Big picture...

High pressure over the southern tier of the USA while closed
upper low hovers near hudson's Bay. This places New England in a
zonal flow with several shortwaves moving through the flow. Models
agree on bringing 3 or 4 shortwaves through our area during the
upcoming week, but with differences in timing. Expect variable
differences to continue with each model run for the next couple of



Upper shortwave and associated surface low are over southern New
England Friday morning, and move off to the east during the day.
Expect lingering scattered showers in northern Massachusetts and on Cape Cod,
diminishing during afternoon. Lingering moisture below 850 mb should
allow partly to mostly cloudy skies through the day with partial
clearing at night. Mixing to 925 mb will allow wind gusts of 30 to
35 knots. Temperatures in the mixed layer will support Max temps in
the upper 40s and 50s.


Shortwave from central Canada sweeps across New England. Timing
currently looks like late Saturday and Saturday night, although the
European model (ecmwf) has passage on Sunday. Wind fields show some upper venting and
low level convergence with this system. Moisture fields show pws of
1.4 inches, but are limited in the vertical with some available
moisture below 700 mb along and ahead of the front. Will forecast
chance pops mainly north of Rhode Island and CT, slight chance farther south.


High pressure builds over the region Monday through Wednesday. This
should be a period of dry weather. Coolest temps aloft are on Monday
with a warming trend through Wednesday.

One upper shortwave passes well to our north on Wednesday. Most of
the support for this remains in Canada, but some indications in the
models that a wind shift may be forced south to our area on
Wednesday. Little or no pcpn is associated with this. Another
shortwave dives south from northern Canada to the Great Lakes
Thursday, and may spread showers our way Thursday night. But timing
on this feature is low confidence at best.


Aviation /03z Thursday through Monday/...
forecaster confidence levels.

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

Short term /through Thursday night/...

Overnight...high confidence. Mainly VFR. Low end VFR to MVFR
ceilings expected over Outer Cape cod and Nantucket. Low
probability of periods of MVFR conditions in ocean effect rain or
snow showers in this area. Northerly winds diminish except for on
the cape and islands where gusty winds continue.

Thursday...high confidence in trends, lower on timing. Conditions
quickly diminish as a mix of snow and rain showers sweep into
southern New England from SW to NE. Most likely period for snow will
be during the morning hours and across northern CT and western and
central Massachusetts. Elsewhere, rain is expected. Snowfall will be light and
no accumulation is expected on pavement. In fact, any accumulation
will likely be limited to the higher elevations (greater than 1500-
2000 ft). All areas of snow should change to rain quickly by 18z.
Northerly winds shift to the east during the day but remain fairly
light until after 21z, when the low level jet kicks up and areas
along the South Coast, cape, and islands will see gusts starting to
increase up to 25 to 30 kts.

Thursday night...high confidence in trends, lower on timing. Rain
will continue through the night with a periods of heavy rain
possible. Expect a mix of MVFR/IFR conditions in rain/fog. On the
coastal plain, the south coasts of Rhode Island/MA, the cape and islands,
easterly to southeasterly winds will gust up to 35 to 40 kts at
times. Elsewhere, winds will be a bit lighter, gusting up to 20 to
25 kts along the East Coast and below 20 kts across the interior.

Kbos taf...high confidence in trends, lower confidence in timing.

Kbdl taf...high confidence in trends, lower confidence in timing.

Outlook /Friday through Monday/...

Friday... moderate confidence.

Areas of MVFR cigs/vsbys in showers early, but trending VFR during
the day. Northwest winds increase with gust potential 30 to 40

Saturday-Sunday... low confidence.

Mainly VFR but with brief MVFR in scattered or widely scattered
showers. Timing is uncertain. West-southwest winds gusting 20 to 25 knots
Saturday, becoming northwest and diminishing Sunday.

Monday-Tuesday... moderate confidence.

VFR. North winds less than 20 knots becoming light variable.


forecaster confidence levels.

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

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

Overnight...winds and seas trend lower as high pressure moves
over the waters. Lingering ocean effect clouds and possibly
rain/snow showers near Cape Cod and Nantucket may limit
visibilities at times.

Thursday...winds and waves will build slowly as low pressure
approaches southern New England from the Great Lakes. Small craft
conditions may be reached by the evening hours but will quickly be
followed by easterly gale force wind gusts.

Thursday night...easterly and then southeasterly gale force wind
gusts are expected Thursday night and into Friday. Gale watches
have been issued for this time for most of the waters. Waves
increase to 7 to 9 feet on the outer waters. Periods of heavy rain
and fog may limit visibilities at times.

Outlook /Friday through Monday/... moderate confidence

Friday... moderate confidence.

Low pressure over southern New England moves off past the Maritimes.
Winds will increase from the northwest with frequent gusts of 35
knots. Seas will hold at 5 to 10 feet on the exposed waters,
diminishing Saturday night. The gale watch has been extended into
Friday on most waters.

Saturday-Sunday... low confidence.

Cold front moves across the waters during the weekend. Low
confidence on timing of the passage. Expect west-southwest winds ahead of the
front with gusts to 25 knots, then northwest winds behind the front with
speeds 15 knots or less. Seas 5 to 9 feet Saturday on the outer
waters and the Rhode Island waters. Seas then diminish Sunday.

Monday-Tuesday... moderate confidence.

High pressure builds fair weather over the waters. Winds less than
20 knots and seas less than 5 feet.


Box watches/warnings/advisories...
Massachusetts...frost advisory until 9 am EDT Thursday for maz007-015-016-019-
Freeze warning until 9 am EDT Thursday for maz014-018-020.
Rhode Island...frost advisory until 9 am EDT Thursday for riz005-007.
Freeze warning until 9 am EDT Thursday for riz001>004-006.
Marine...gale watch from Thursday evening through Friday afternoon for
Gale watch from late Thursday night through Friday morning for
Gale watch from late Thursday night through Friday afternoon
for anz250-251.
Gale watch from Thursday evening through Friday afternoon for


near term...wtb/evt
short term...rlg
long term...wtb

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