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Area forecast discussion 
National Weather Service Taunton Massachusetts
811 am EDT Wednesday may 6 2015

dry weather with unseasonably warm afternoon/S will continue into
the weekend. The potential for wet weather and cooler
temperatures may finally arrive late Sunday into early next week.


Near term /until 6 PM this evening/...
8 am update...

Area of mainly light showers continues to pass S of the region.
Noting sprinkles reported at a few sites across S CT to Li and
NYC at 12z. Noting broken-overcast middle and high level clouds across the
region...with some lower clouds /around 5-6kft/ across Cape Cod
and the islands. Current trends suggest mainly east-southeast movement...
but expect precipitation and cloud deck to shift S as high pressure builds in
through the remainder of the day.

Light/variable or calm winds in place. Still expect sea breezes to
develop late this morning along coastal areas.

Near term forecast has been updated to bring conditions current.
Noted dewpoints milder than forecast across east Massachusetts/RI/NE CT...but
started to fall over north and west Massachusetts as drier air begins to work in.
Remainder of forecast pretty much on track.

Previous discussion...
skies should become mostly sunny from north to south later this
morning and afternoon which is supported by model cross sections.
Given relatively low dewpoints and dry ground with lack of recent
rainfall...highs should climb well into the 70s to near 80. The
exception will be along the immediate coast...where sea breezes
will hold temperatures mainly in the 60s.


Short term /6 PM this evening through 6 PM Thursday/...
***cool temperatures early Thursday morning across outlying
locations will give way to a warm afternoon***


High pressure overhead and mainly clear skies should lead to a good
night of radiational cooling. Low temperatures will fall into the lower
40s across the normally coolest outlying locations with perhaps even
a few upper 30s. Meanwhile...portions of the higher terrain and
downtown Boston will see low temperatures will only drop into the lower to
middle 50s.


A ridge of high pressure...combined with a relatively dry airmass in
place will allow for a quick recover in cool early morning temperatures
across the outlying locations. Plenty of sunshine and 850 temperatures
between +10c and +12c...should allow afternoon highs to reach into
the lower to middle 80s away from the coast. Sea breezes along the
eastern Massachusetts coast may be overcome by late afternoon...allowing even
these locations to see a late afternoon surge to around 80 degrees.
Although it will be will be comfortable outside with
relatively low dewpoints in place.


Long term /Thursday night through Tuesday/...

* SW flow will bring mild to warm temperatures through this
weekend for most areas
* low clouds and fog each overnight/morning with onshore winds
* increasing chance for showers from late Sunday into early next

Discussion and model preferences...

Continued 500 mb long wave blocking pattern remains in place for most
if not the entire long term forecast period with eastern U.S.
Ridging and blocking cutoff low pressure/trough across the west. May
start to see pattern breaking down...though some timing
differences amongst the operational models from late Sunday
through early next week lowered confidence during this timeframe.

Expect dry conditions to continue Thursday night through Sat as high
pressure ridge builds slowly east...allowing winds to shift to S-SW. Mild
to warm temperatures will continue through Sunday as dewpoints slowly but
steadily rise with the deep onshore flow. Temperatures along the S coast
will be cooler with the onshore winds as well. Will also see
development of low clouds and patchy fog each late night to middle
morning period along the coast dewpoints increase...across
susceptible inland areas by this weekend.

May start to see a very slow moving front out of southern Quebec
and northern New England bring a few showers later Sunday into
Sunday night mainly across north Massachusetts around the Route 2 area. Some more
instability also looks to work can not rule out a rumble
of thunder or two but tough to determine placement so left out
mention for now. Noting the 00z GFS op run trying to break down
the upper ridge and therefore moving the front faster toward the
region than the 00z GFS/ECMWF. Another factor is the developing
coastal low off the middle Atlantic/southeast U.S. Coast that may take on
subtropical characteristics. All op models appear to stall this
feature...which in turn should also help keep the upper ridge in
place and slow the progression of the front.

Models and ensembles showing progression of the cutoff low out of
The Rockies and plains states toward the Great Lakes by Monday night
into Tuesday...with associated low pressure/cold front that tries to push
the ridge and coastal low offshore. This appears to be the best
chance for showers along with better shot for convection but
again timing is the issue. Noted potential for periodic heavy
rainfall that may tend to train across the region as the front
slowly crosses as mentioned by previous forecaster...but too
early to tell how much at this point. Rather low confidence during
this timeframe.

Went with a blend of the available guidance into this weekend...
then transitioned to a blend of ensemble guidance from late Sunday
Onward which appeared to give better resolution of the timing
differences as slow moving front starts to sag toward the region.


Aviation /12z Wednesday through Sunday/...
forecaster confidence levels...

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

Short term /today through Thursday/...

Today through Thursday...high confidence.
VFR conditions. Sea breezes develop by around midday along the
immediate coasts...then should come to an end by early evening.

Kbos taf...high confidence in taf. East to northeast sea breezes
expected to develop by middle morning and shift to an east southeast
direction by afternoon. Winds will then finally shift to the
southwest by early evening as sea breezes come to an end.

Kbdl taf...high confidence in taf.

Outlook...Thursday night through Sunday...moderate confidence.

VFR. Expect S-SW winds. May see periods of IFR conditions in fog
and low clouds mainly along the S/southeast shoreline terminals during
overnight into the morning periods each day. Increasing chances
for -shra Sunday.


forecaster confidence levels...

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

Short term /today through Thursday/...

Today through Thursday...high confidence. High pressure nearby will
keep winds and seas below Small Craft Advisory thresholds through
Thursday afternoon. Seas generally 1 to 3 feet with good visibility.

Outlook...Thursday night through Sunday...moderate confidence.

Expect winds and seas to remain below small craft criteria through
the period. S-SW winds may gust up to 20 knots at times mainly across
the outer waters. Visibilities will be reduced each overnight into
early morning hours in low clouds and fog.


Fire weather...
dry weather will continue through at least Saturday if not into
Sunday. Minimum afternoon relative humidity values will drop to
between 15 and 25 percent this afternoon and again Thursday
afternoon. While winds will probably not be strong enough through
the rest of the work week for fire weather headlines...we may
have to be more concerned this weekend if it remains dry.


Box watches/warnings/advisories...
Rhode Island...none.


near term...Frank/evt
short term...Frank
long term...evt
fire weather...Frank

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