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Area forecast discussion
National Weather Service Taunton Massachusetts
1027 PM EDT Thu Oct 19 2017

Synopsis...
high pressure will maintain dry weather and warmer than normal
temperatures through the weekend. The risk of showers will
increase by the middle of next week.

&&

Near term /until 6 am Friday morning/...
1020 PM update...

Winds have diminished considerably over the interior but
latest check with steamship authority shows 20-30 kt gusts
continuing on Nantucket and Vineyard sounds. Have increased
winds in that area and prolonged them for a few additional hours
overnight...hence have extended small craft advisories for the
southeast waters through 10z.Lows will mainly be in the upper
30s and range from the upper 30s and 40s...which is about
normal. Expect min temps in the 40s and low 50s.

Temperatures and dewpoints right on track, so no changes made.

Mid level trough will be racing across the northeast state
overnight with a weak cold front causing a wind shift to the
northwest. Mainly high clouds, but the narre, which performed
well last night, is showing the development of a brief period of
low cloudiness in the slopes of the Berkshires and into the CT
River Valley toward daybreak. Will keep an eye on this.
Some patchy fog cannot be ruled out in areas that have good
radiational cooling overnight. Lows mainly in the 40s except
lower 50s Cape Cod and islands.

&&

Short term /6 am Friday morning through Friday night/...
high pressure remains in control with dry weather and mainly clear
skies. Main difference from today will be that winds will be
from the northwest and bringing slightly lower dew points.
Mixing during the day will reach 925 mb or a little higher,
similar to today, with temps at that level supporting Max sfc
temps of roughly 65-70f.

At night, light wind with dew points 35-45 will allow
radiational cooling to bring min sfc temps in the upper 30s and
40s.

&&

Long term /Saturday through Thursday/...
highlights...

* warm and dry this weekend lasting into Monday
* unsettled weather pattern with showers at times Tue into Thu

Overview...

Strong subtropical ridge along the East Coast will maintain warm and
dry conditions into early next week. Then models signal a pattern
change with significant amplification of the large scale flow as
northern stream trough digs south from the Great Lakes to the southeast USA
and interacts with southern stream energy with an eventual high
amplitude trough setting up across the eastern Seaboard. With
downstream ridging shifting over the Atlantic, there could be a
period of unsettled weather sometime in the Tue to Thu timeframe but
timing and details remain uncertain in this developing complex
pattern.

Saturday through Monday...

High pres in control with building mid level ridge will result
sunshine and unseasonably warm weather. With 925 mb temps 17-18c
should see highs reach well into the 70s this weekend but somewhat
cooler along the South Coast with SW flow. Warm and dry conditions
last into Mon.

Tuesday through Thursday...

Unsettled with showers at times as amplifying trough sets up to the
west with slow moving frontal boundary approaching and multiple
shortwaves moving through the flow. Timing and details of rainfall
remain uncertain but it appears there will be one period of rainfall
sometime Tue into Tue night with lead southern stream shortwave
lifting to the NE. Then possibly a break followed by another period
of rain Thu and beyond as frontal boundary stalls with another
system approaching. Very complex pattern so further forecast changes
expected. Temps above normal through Wed, but lower confidence Thu.

&&

Aviation /02z Friday through Tuesday/...
forecaster confidence levels...

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

Short term /through Friday night/...generally high confidence.

Overnight...

A weak cold front crosses the region tonight, but with very
limited moisture, so just a few high clouds. The main effect
will be a shift of diminishing winds with winds coming from the
northwest overnight.

Radiational cooling will allow patches of fog to develop later
tonight, especially in parts of the CT River Valley and in the
usual fog magnets. Vsbys could drop to 1/2 mile in spots after
midnight. Could also see some low clouds/IFR ceilings developing
in the slopes of the Berkshires and into the CT River Valley.

Friday and Friday night...

VFR conditions continue. Areas of fog will dissipate first thing
Friday. Northwest winds will pick up a little, with late morning
and afternoon gusts near 20 knots. Winds then diminish with
sunset.

Kbos terminal...high confidence in taf.

Kbdl terminal...high confidence in taf. Will need to watch for
a possible brief period of low clouds near the Airport toward
daybreak, though.

Outlook /Saturday through Tuesday/...

Through Monday...high confidence. VFR, but patchy late night fog
possible in the typical locations.

Tuesday...moderate confidence. MVFR possible in developing
showers.

&&

Marine...
forecaster confidence levels...

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

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

Overnight...have extended the small craft advisories for all
waters, except Boston Harbor and Narragansett Bay through the
overnight hours. Latest check from the steamship authority
shows gusts of 20-30 kt continuing over Vineyard and Nantucket
sounds. Models show the gradient slowly weakening there toward
daybreak. Seas on the outer waters will hover around 5 feet,
and while the flow is from the southwest these 5 foot seas may
work into Rhode Island Sound as well. Winds will shift to the northwest
later tonight, at which point the seas will diminish.

Friday...northwest winds will gust around 20 knots during the
day. Seas will remain 4 feet or less through the day.

Friday night...winds remain 15 knots or less, and seas remain at
3 feet or less.

Outlook /Saturday through Tuesday/...high confidence.

Great boating weather through Mon with SW winds below 20 kt and seas
below Small Craft Advisory thresholds as high pressure prevails. Increasing southerly
winds Tue as low level jet develops. High prob of Small Craft Advisory winds with low
risk for gales. Increasing threat of showers with reduced vsbys
Tue.

&&

Fire weather...
winds shift to the northwest overnight. On Friday these
northwest winds will gust around 20 mph, with minimum relative humidity values
reaching 30-35 percent across much of the region. Thus there
could again be some risk of elevated fire weather potential. A
Special Weather Statement highlights this potential.

&&

Box watches/warnings/advisories...
CT...none.
Massachusetts...none.
Rhode Island...none.
Marine...Small Craft Advisory until 6 am EDT Friday for anz231>234-250-
251-254.
Small Craft Advisory until midnight EDT tonight for anz230-236.
Small Craft Advisory until 7 am EDT Friday for anz235-237-255-
256.

&&

$$
Synopsis...wtb/kjc
near term...wtb/kjc/gaf

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