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Area forecast discussion 
National Weather Service Taunton Massachusetts
709 PM EDT Monday Sep 15 2014

Synopsis...
a cold front will sweep southern New England bringing with the
chance of scattered showers beginning after midnight tonight
through Tuesday. Mainly dry but cooler than normal weather follows
Wednesday through Saturday. Temperatures then moderate to near
normal by the end of the weekend.

&&

Near term /through Tuesday/...
715 PM update...made a few minor edits to the forecast based on
latest trends. Otherwise the forecast is on track. A few middle level
clouds are hanging around southeastern mass otherwise...mostly
clear skies for the time being.

Into tonight...

A fall-like chill remains in the air as scattered to broken
pancake cumulus linger across the sky. Should see present high
temperatures around the upper-60s drop towards the lower-60s by
Sundown.

Tonight into Tuesday...

A modest middle-level impulse will invoke weak troughing as it rounds
the base of a deeper-low over the NE-Canadian Maritimes. Considering
low-level convergence of a Continental-moist airmass undergoing middle-
level enhanced ascent collocated with a region of frontogenetical
forcing and right-entrance-region of the upper-level jet /whew/...
would expect scattered light to moderate shower activity along a
line ahead of the surface cold front. The latest hrrr is showing
such a trend fairly well across the east Great Lakes by midnight
Tuesday.

But a few things worthy of note...not an impressively moist-airmass
with precipitable waters of 1.00-1.25 inches. Subsidence and dry air continue to
prevail southeast...squeezed between the approaching middle-level impulse and
well-offshore subtropical axis buckled by the meandering Hurricane
Edouard. Anomalously cooler for this time of year over much of the
region...low confidence concerning thunder and instability.

So will not go with a mention of thunder. Not expecting a washout.
Will keep the highest categorical probability of precipitation towards the west especially
along the slopes of higher terrain. Will taper to chance probability of precipitation off
towards the southeast as accompanying dynamics to the disturbance shift to
the NE shunting the surface cold front into a region of subsidence
and drier air. Elsewhere...expecting around a tenth for areas of west
New England...with a few hundredths across central and east. Many not
see any precipitation whatsoever for east/southeast Massachusetts.

&&

Short term /Tuesday night/...
Tuesday night...

Cold front pushing offshore. Some breezy north/NW-flow rearward is
certainly plausible initially...but high pressure quickly follows
allowing winds to relax.

Though the possibility of some middle-level scattered cloud decks will
exist...there is also the potential of effective radiational cooling
overnight which would likely result in abnormal lows into the 40s
along with areas of dense fog...especially for those regions that
received a modest rain over the past 24 hours /thinking the west-
and central-interior...especially the middle-CT River Valley/.

Lows into the 40s with the potential for upper-30s across the high
terrain of north/west Massachusetts and S New Hampshire.

&&

Long term /Wednesday through Monday/...
highlights...

* mainly dry and cooler than normal weather through Saturday
* temperatures moderate going into the weekend
* a cold front brings some rain to the region Sunday into Monday

Models...including ensembles...are in good agreement through much of
the long term with only some minor detail differences. Therefore...
will use a blend of available guidance for much of the forecast.
Points of interest include the potential for cold temperatures and
frost for Thursday night into Friday and a cold front bringing
rain to the region Sunday into Monday.

Wednesday and Thursday...a broad upper trough over the northeast US
will slowly move offshore during this time. High pressure builds
over southern New England bringing and slightly cooler than normal
temperatures and dry weather to the region.

Friday...this is the coolest day by far with low temperatures Friday
morning expected to be in the low to middle 30s across portions of the
far interior and in the upper 40s along the coast. High
temperatures will then be a good 10 to 15 degrees below normal.
Other than the temperatures...expect a pleasant day with mostly
clear skies as high pressure remains over the region.

Saturday through Monday...temperatures start to moderate through the
weekend with warming southerly surface winds in place ahead of a
cold front stemming from an intensifying area of low pressure just
north of the Great Lakes. This is associated with a deep upper
level trough over the Great Lakes that will slowly move over
southern New England and then offshore by early next week. Expect
some rainfall ahead of the cold front Sunday and Monday. Models
are indicating some instability so thunder is a possibility at
this point...but will leave it out since much could change in the
next week.

&&

Aviation /23z Monday through Saturday/...
forecaster confidence levels...

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

Short-term forecast /through Tuesday night/...high confidence.

Tonight...rain showers after midnight for west-terminals dissipating as they
spread east. Will hold with low-end VFR ceilings with only perhaps MVFR
for S-coastal terminals. Winds turning S.

Tuesday...rain showers dissipating as SW-winds shift out of the west-northwest
with the cold frontal passage. Low-end VFR ceilings overall with
perhaps some MVFR lingering along the S-coast during the morning.

Tuesday night...VFR with winds becoming vrb. Dense fog possible
for the west-interior terminals...especially the CT-valley from kbaf
northward.

Kbos terminal...high confidence in taf.

Kbdl terminal...high confidence in taf.

Outlook...Wednesday through Friday.

Wednesday through Friday...high confidence. VFR.

&&

Marine...
forecaster confidence levels...

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

Short-term forecast /through Tuesday night/...moderate confidence.

While the weather will be for the most part quiet with a dry cold
frontal passage expected for late Tuesday /winds out of the SW
shifting out of the W-NW/...main concern is the anticipated swell
and waves associated with Edouard.

With Edouard far removed from the coast...and overdone forecast
models with regards to seas...have held wave heights no greater
than 5 feet. Have also held off on the issuance of small-craft
advisories for seas. Will re-evaluate as we get closer to the
potential for significant wave heights and possible rip current
threat beginning Tuesday night towards Wednesday.

Outlook...Wednesday through Saturday...

Wednesday through Friday...lingering swell from Hurricane Edouard
/keeps well out to sea/ keeps seas in the 5 to 6 foot range on the
outer waters. Winds will remain fairly light and variable through
Thursday with high pressure over the waters. Northeasterly winds
may gust to near 25 kts Friday afternoon as the high shifts eastward.

Late Friday night into Saturday...quiet boating weather expected.

&&

Box watches/warnings/advisories...
CT...none.
Massachusetts...none.
New Hampshire...none.
Rhode Island...none.
Marine...none.

&&

$$
Synopsis...rlg/sipprell
near term...rlg/sipprell
short term...sipprell
long term...rlg
aviation...rlg/sipprell
marine...rlg/sipprell

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