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Area forecast discussion 
National Weather Service Taunton Massachusetts
236 am EDT Sat Aug 27 2016

high pressure builds over northern New England, bringing dry
weather for much of this weekend. There is the chance of showers
and thunderstorms Sunday into Monday ahead of a sweeping cold
front. A brief period of high pressure follows for Tuesday prior
to another cold front for Wednesday with another chance of wet
weather. Low confidence forecast from Thursday Onward as competing
airmasses present the double-sided possibility of either wet
weather or remaining completely dry.


Near term /through today/...
cold front had finally moved past Nantucket around 2 am, and will
continue to slowly move offshore the rest of today. Meanwhile,
high pressure will move east across southeast Canada.

Dew points around 60 degrees will be more common today, which is
about a 10 degree drop from Friday. Max temperatures will be a
little, too. The lower temperatures will be more noticable toward
the coasts, where seabreezes will develop later this morning.


Short term /tonight through 6 PM Sunday/...

The center of the high pressure shifts east tonight into Sunday.
Expecting mainly clear skies and light winds to prevail through
this portion of the forecast. Once the high pressure reaches the
Maritimes late Sunday, there is a small possibility for a mid
level shortwave to bring isolated showers to northwest Massachusetts late in
the day.

Temperatures expected to be slightly above normal, despite
seabreezes along both coasts Sunday.


Long term /Sunday night through Friday/...
*/ highlights...

- shower and thunderstorm chances Sunday night into Monday
- keeping it dry for Tuesday
- another cold front and chances of wet weather for Wednesday
- low confidence forecast from Thursday Onward
- keeping invest-99l out of the picture and out to sea

*/ discussion...

Interpreting the north hemispheric pattern. Atmospheric teleconnections
continuing a -wpo/-epo trend through the beginning of September with
a waffling pna. Of certainty, we're seeing a buckling in the height
pattern across the North Pacific in concert with a -wpo/-epo yielding a
high latitude block and stronger than normal Pacific jet within the
deepening troughs. Given the pna trend, there is no clear signal as
to outcomes downstream. Nevertheless, during -epo/-wpo trends it is
noted that anomalous cyclonic circulations can occur over east portions
of North America, drawing cooler air S. So while the late-August early-
September cyclone in vicinity of the NE Continental U.S. Per deterministic
guidance may seem erroneous, it can not entirely be rule out. Will
for the sake of simplicity keep with an ensemble-weighted forecast.
Inclined to believe per ensemble members and deterministic forecasts
that at this point whatever becomes of invest-99l (al99) will sweep
out North/East ahead of preferred troughing prior to and during the Labor
Day Holiday weekend.

So will lean with the following forecast: Sunday night into
Monday a deamplifying disturbance which will introduce lower
heights and cyclonic flow, a slight kink to the near-zonal flow.
Surface cold frontal feature, there is the chance of showers and
thunderstorms. Prefer to keep it dry for Tuesday. Another cold
front for Wednesday and the chance of showers and thunderstorms.
Thursday and Friday remain up in the air. If a deep cyclone does
develop and remains in the vicinity of the NE conus, then the
combination of cooler air aloft and daytime heating/destabilizing
boundary layer below, along with continued impulses through the
cyclonic flow, could yield a setup for diurnally-forced storms.
But it is possible that drier air and high pressure win out. Toss
up at this point and subsequently a low confidence forecast. For
Labor Day weekend, going by ensemble means, it does appear the
trough-ridge- trough pattern across the Continental U.S. Shifts subtly east
thereby putting the NE Continental U.S. At least the influence of high
pressure. As to airmass depends on the preferred wind flow aloft
(i.E., Northwest vs. Sw). No threats or impacts just yet to speak of
throughout the long-term forecast, as well as no end in sight with
regards to current drought conditions.


Aviation /06z Saturday through Wednesday/...
forecaster confidence levels.

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

Short term /through Sunday/...

Today...high confidence.

VFR. Light north winds, with seabreezes developing along both

Tonight...high confidence.

VFR. Light and variable wind. Patchy fog after midnight in the
usually prone locations, mainly in the CT River Valley, with
IFR/LIFR cigs/vsbys through sunrise.


VFR with winds turning S and increasing. Increasing mid and high
clouds across the region, with the possibility of a few rain showers north/west
late in the day.

Kbos terminal...high confidence in taf.

Kbdl terminal...high confidence in taf.

Outlook /Sunday night through Wednesday/...moderate confidence.


Chance of shra/tsra. S/SW winds, breezy with gusts up to 20 kts,
backing out of the west/northwest towards Monday evening.


Will prevail VFR with west/northwest winds initially veering out of the S/SW.
Anticipating increasing mid to high cloud late in the period.


Chance of shra/tsra. S/SW winds, breezy with gusts up to 20 kts,
backing out of the west/northwest during the evening into overnight period.


forecaster confidence levels.

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

Short term /through Sunday/...high confidence.

Winds and seas expected to remain relatively light through Sunday.
Seabreezes near shore expected both today and Sunday. Seas
increase across the outer coastal waters Sunday in response to
arriving southeast swell from distant Tropical Storm Gaston.

Outlook /Sunday night through Wednesday/...


Chance of showers and thunderstorms, mainly over the near-shore
waters. S/SW winds, breezy with gusts up to 20 kts continuing,
backing out of the west/northwest towards Monday evening with a cold frontal
passage. Persistent wind stress plus swell associated with Gaston,
will introduce 5 foot seas on the outer waters.


West/northwest winds initially, fairly benign, veering out of the S/SW through
the day. Will keep it dry. Continued swell from Gaston, will keep
with 5 foot seas on the outer waters.


Another cold front and another chance of showers and thunderstorms.
S/SW winds ahead of the front with gusts up to 20 kts, backing out
of the west/northwest into the evening and overnight period.


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


near term...Belk
short term...Belk
long term...sipprell

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