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Area forecast discussion 
National Weather Service Taunton Massachusetts
946 am EST Wednesday Nov 25 2015

high pressure remains an influence across New England through the
end of the week during which time temperatures gradually warm as
the high moves offshore. A cold front from Canada will cross the
region Friday night and Saturday. High pressure then brings dry
weather through early next week. Another storm may affect New
England on Tuesday.


Near term /until 6 PM this evening/...
945 am update...
strong high pressure over new eng will move to Nova Scotia by this
evening. Developing low level southeast flow will result in marine air
advecting into SW new eng this afternoon below subsidence
inversion. Clouds are already developing across eastern Long
Island and Li sound. These clouds expected to expand northward
across CT and SW Rhode Island through this afternoon as soundings show
shallow moisture developing in the 925-900 mb layer. Adjusted sky
grids to reflect this. High temperatures will reach middle/upper
40s...cooler higher terrain.


Short term /6 PM this evening through 6 PM Thursday/...
tonight ...

Some concern as to the development of drizzle during the overnight
period ... though not absolutely confident it will develop.

With continued cooling and moistening within the first few thousand
feet above the surface pooling beneath the dry-inversion ... marine
stratus should thicken lessening entrainment impact. Flush with
cloud-condensation-nuclei per fetch off the waters ... should a
roughly consistent high relative humidity profile exist from the
surface to the marine layer ... drizzle would become a factor across
portions of S New England.

But some nuances among the forecast guidance ... 1. Breadth of
the stratus deck ... and 2. Whether the low-level profile is
uniform with respect to relative humidity or rather if dry air
still hangs around. Somewhat difficult to nail down if and where
exactly drizzle will be an issue. Will lean with a slight chance
for now. Perhaps some issues with patchy dense fog though low-
confidence at this time.

Otherwise onshore flow of higher dewpoint air coupled with the
marine deck forecast ... should be warmer overnight compared to as
of late with lows around the freezing mark. Will be colder for those
areas which find themselves void of any stratus deck.

Thursday ...

Though moisture continues to pool beneath a dry-subsidence inversion
associated with the 1050 high to the east ... feel warming through the
day will increase boundary-layer mixing and the entrainment of dry
air through the marine layer thus limiting drizzle potential. The
uniform moist profile necessary would no longer be maintained.

Not ruling out some breaks of sunshine coupled with the onshore S-
flow ... as warm-dry air filters in from the SW aloft ... will keep
going with a moderating temperature trend warming into the middle- to


Long term /Thursday night through Tuesday/...
big picture...

A West Coast Rex block during the Holiday breaks up late in the
weekend. This maintains northern and southern streams for much of
the long range period with two features of interest.

Northern stream shortwave advances across New England Friday
night/Saturday driving a cold front through our area. There is
sufficient model agreement to have moderate to high confidence in
the consensus depiction.

The second feature is a closed low...part of the West Coast Rex
block...ejecting east Sunday. This forms a surface weather system
over the plains and an area of rain...then drives it northeast
toward New England for next Tuesday or Wednesday. Timing of the West
Coast ejection and East Coast arrival are more realistic than last
night...and model to model differences are less dramatic with this
model set. But run to run differences are still of some concern so
confidence is low to moderate.

The dailies...

Thursday night...cross sections show plenty of moisture below 850 mb
in the low level south flow. This suggests low clouds much of the

Friday... high pressure offshore with low level south flow and upper
level southwest flow. Both the surface cold front and most of the
favorable jet dynamics aloft remain over northern New England
through the day. Main concern will be the amount of low level depicted by model cross sections...and resulting cloud
cover. Model sky cover grids are not picking up on this low level
moisture very well. We will continue to split the difference with a
partly cloudy forecast. With sufficient sun the mixing of the low
level temperatures would support maximum surface temperatures in the upper 50s and low 60s.

Friday night-Saturday... cold front across northern New England and
central New York moves southeast across southern New England late
Friday night or early Saturday morning. Best dynamics remain to our
north but sufficient low level convergence with a 1.2 inch precipitation
water content to support chance probability of precipitation with the frontal passage. High pressure
and north wind will bring drier air and clearing skies Saturday
afternoon and night. Mixing should reach to 925 mb where temperatures will
support surface maxes in the low to middle 40s.

Sunday-Monday... another northern stream shortwave breezes through
on Monday but with limited lift and moisture. Otherwise high
pressure dominates both days. Mixed layer temperatures both days support
maximum surface temperatures in the 40s.

Tuesday... ejecting upper low from the west. Leading difluent zone
reaches New England toward midday Tuesday. Also increasing moisture
at or below 700 mb midday and afternoon. Expect increasing clouds
along with a chance of showers. Better chance Tuesday night.


Aviation /15z Wednesday through Sunday/...
forecaster confidence levels...

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

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


VFR sky clear...but broken ceilings around 4k feet developing across north CT and SW
Rhode Island after 18z which may affect bdl and pvd. Light variable wind
turning southeast along the coast...eventually south toward

Tonight and Thursday ...

Scattered-broken low-end VFR to MVFR ceilings encroaching from the S moving to
the north with S/se-onshore flow. Slight chance -dz Wednesday night
into Thursday morning.

Kbos terminal...high confidence in taf.

Kbdl terminal...high confidence in taf.

Outlook /Thursday night through Sunday/.....Moderate confidence

Thursday night-Friday...
primarily MVFR Thursday night in ceilings. But concern that
increasing south winds aloft may support drizzle and IFR ceilings.
Best chance would be along the South Coast. Conditions improve to
VFR Friday.

Friday night-Saturday... VFR much of the time. Cold front moves
through late night and Saturday morning. A few showers possible
Friday night and Saturday morning with MVFR cigs/vsbys.



forecaster confidence levels...

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

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

Winds and seas remaining below small-craft criteria. Light wind will
shift out of the southeast around midday and remain that way into
Thursday. Strongest of the winds will be on Thursday with gusts
up to 20 kts over the E-waters.

Outlook /Thursday night through Sunday/...

Thursday night-Friday...high confidence.
High pressure over the waters shifts east Friday. This will mean an
increasing south flow turning southwest. The steady flow will remain
below 25 knots...but will build seas with heights reaching 5-6 feet
on the outer waters late Friday. Small Craft Advisory may be needed
on the outer waters late Friday.

Friday night-Saturday...moderate-high confidence.

Cold front sweeps across the waters late Friday night or Saturday
morning. Southwest winds ahead of the front will increase to 20-25
knots with seas building to 5-6 feet over a broader area. Winds will
then shift north or northwest Saturday morning with gusts 25-30
knots over most waters and 5-8 foot seas. Small Craft Advisory will
be needed for most of the waters.

Saturday night-Sunday...moderate confidence.
High pressure builds over the waters bringing diminishing wind. Seas
will subside below 5 feet by Sunday. Any lingering small craft
headlines should come down on Sunday.


record highs Friday 11/27...


Record high mins Friday 11/27...



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


near term...kjc
short term...sipprell
long term...wtb

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