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Area forecast discussion
National Weather Service Taunton Massachusetts
337 am EST Sat Nov 25 2017

Synopsis...
milder air returns today ahead of a cold front, which will bring
scattered showers as it crosses the region tonight. Blustery
and colder weather follows Sunday. Milder temperatures return
Tuesday and Wednesday before cooler weather returns later next
week.

&&

Near term /until 6 PM this evening/...
clear skies at the moment, but high-res models still insistent
that low clouds will develop before daybreak across southern Rhode Island
and southeast MA, especially on Cape Cod and islands as moisture
becomes trapped beneath inversion. Already seeing some evidence
of this on GOES-16 fog imagery south and east of Nantucket and
kfmh has been in and out of clouds overnight. Model cross
sections indicate these clouds will hang on through much of
morning before inversion mixes out.

Elsewhere, expect sunshine to start day followed by increasing
clouds. Increasing SW winds, gusting to 20-25 mph mainly near
coast, will help boost highs well into 50s if not around 60 in
spots. Models have backed off on timing of cold front and any
showers moving into sne, so am limiting mention of showers to
western Massachusetts.

&&

Short term /6 PM this evening through 6 PM Sunday/...
cold front crosses southern New England tonight from west to east, accompanied by
scattered showers. Models continue to indicate limited moisture
and weak convergence along front, so not looking for widespread
or heavy rain, as most places should only pick up a few
hundredths of an inch.

Strong cold advection gets underway Sunday on gusty northwest winds as
front moves offshore. Upper trough crosses area in morning and
should be able to produce scattered flurries as it moves
through, due to leftover moisture and falling temperatures
aloft with steepening lapse rates. It's possible we see some
briefly heavier snow showers across northern MA, especially
near Merrimack valley where stronger lift is expected, but
confidence is low. In any case, surface temperatures will be
warm enough to prevent much in way of accumulation.

Clearing follows Sunday afternoon as subsidence follows behind
trough and drying works into region. Forecast soundings show
potential for 25-35 mph gusts, which should subside toward
sunset. Followed a MOS blend which gives highs in the 30s in
parts of western/central Massachusetts to 40s elsewhere.

&&

Long term /Sunday night through Friday/...

25/00z guidance is in rather good overall agreement through
Tuesday, leading to high confidence for that portion of the
forecast. Beyond Tuesday, operational guidance has very
different timing for a potent shortwave moving through the
northern stream from the Gulf of Alaska. Thus the forecast for
the second half of next week has more uncertainty than usual.

Overall, expecting a persistent mid level trough to finally
move over the Maritimes Monday. This will transition the flow
over southern New England to a more zonal flow through the
middle of next week. Guidance all agrees on another deep trough
developing over the eastern USA late the week. The question is
when it should impact our region.

Moisture looks to be lacking for much of next week,
particularly in the lower levels. Expecting some clouds from
time to time, but not much rainfall through the first half of
next week.

As for temperatures, looking for a warm up towards Wednesday.
Otherwise, near to slightly below normal temperatures are
expected.

&&

Aviation /08z Saturday through Wednesday/...
forecaster confidence levels...

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

High confidence through Sunday.

MVFR ceilings around 015 may develop across southern Rhode Island and
southeast Massachusetts 09z-15z, especially on Cape Cod and islands. Otherwise
VFR today with S-SW winds gusting to 20-25kt this afternoon,
especially near coast. VFR ceilings 040-060 develop from west to east
this evening with isolated -shra, which end overnight as winds
shift to west. VFR with increasing west/northwest winds Sunday. Could see
brief period of snow flurries during morning.

Kbos terminal...high confidence in taf.

Kbdl terminal...high confidence in taf.

Outlook /Sunday night through Wednesday/...

Sunday night: VFR. Windy with local gusts to 30 kt.

Monday through wednesday: VFR. Breezy.

&&

Marine...
forecaster confidence levels...

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

Short term /through Sunday/...moderate confidence.

Small Craft Advisory remains posted for waters off Cape Ann
for lingering 25kt winds and 5 ft seas, which will diminish by
early afternoon. Otherwise winds and seas stay below Small Craft Advisory into
tonight as SW winds shift to west/northwest overnight as cold front heads
offshore.

Strong cold advection behind front will bring frequent 25-30kt
gusts to all waters Sunday, especially during afternoon, so scas
have been expanded to all waters. There is potential for a few
marginal gale force gusts to 35kt, especially on outer waters,
but confidence is not high enough for gale watches per
collaboration with neighboring offices.

Outlook /Sunday night through Wednesday/...

Sunday night: low risk for Small Craft Advisory winds with
gusts up to 30 kt. Local rough seas.

Monday: moderate risk for Small Craft Advisory winds with gusts
up to 25 kt. Local rough seas.

Monday night: winds less than 25 kt. Seas locally approaching
5 ft.

Tuesday: winds less than 25 kt.

Tuesday night: moderate risk for Small Craft Advisory winds
with gusts up to 30 kt. Seas up to 5 ft.

Wednesday: low risk for Small Craft Advisory winds with gusts
up to 25 kt. Local rough seas.

&&

Box watches/warnings/advisories...
CT...none.
Massachusetts...none.
Rhode Island...none.
Marine...Small Craft Advisory from 6 am to 6 PM EST Sunday for
anz230>237-251-254>256.
Small Craft Advisory until 1 PM EST this afternoon for anz250.

&&

$$
Synopsis...Belk/jwd
near term...Belk/jwd

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