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Area forecast discussion 
National Weather Service Taunton Massachusetts
352 am EDT Friday Jul 31 2015

Synopsis...
patchy fog and low clouds early this morning gives way to drier
and less humid weather this afternoon...but it will remain very
warm. Seasonably warm this weekend with the risk of few showers
and thunderstorms possible Saturday. Warm weather continues into
early next week along with the risk of thunderstorms both Monday and
Tuesday. Not as warm and less humid conditions arrive middle to late next
week.

&&

Near term /until 6 PM this evening/...

330 am update...

Cold front has progressed into eastern Massachusetts at 3 am with a wind
shift to the west-southwest. Drier/less humid air lags a bit to the west with
psf and aqw dew points down into the u50s! However decoupling blyr
and dew points still in the u60s and l70s across much of the region
is resulting in radiational fog across interior CT and Massachusetts. Along
the South Coast including Cape Cod and the islands low clouds
persist as well. However shortly after sunrise as solar heating
begins to deepen blyr low level moisture will mix out and result
in dew points falling into the 50s with winds shifting to the west
and eroding shallow fog and stratus.

Thus a very nice day ahead with Post frontal airmass offering plenty
of sunshine /BUFKIT relative humidity profiles very dry/...temperatures well into the
mu80s but dew points falling into the 50s...yielding much lower
humidity than yesterday. A few locations including Boston may
briefly touch 90 this afternoon. This would make it an official
heat wave /3 consecutive days of temperatures 90+/ for Boston. Also a
modest west wind at 15 to 20 miles per hour will help take the edge off the
warm temperatures.

&&

Short term /6 PM this evening through 6 PM Saturday/...

Tonight...

Quiet weather along with seasonable temperatures as lows dip into the 60s
regionwide. Only wrinkle is a low risk of a few showers toward
morning as next northern stream short wave approaches from the
west. Greatest risk for showers will be across western sections of
Massachusetts and CT.

Saturday...

Northern stream short wave trough moves across the area. Moisture
is lacking through the column but modest forcing for ascent should be
sufficient to trigger scattered showers. This seems reasonable as
all global and hi res guidance generates widespread quantitative precipitation forecast Sat.
Although 00z NAM quantitative precipitation forecast seems too bullish. Instability is lacking as
surface dew points will be in the u50s to l60s. However cooling temperatures
aloft with approaching trough/height falls will steepen lapse
rates a bit. Middle level trough also increases deep layer shear up
to about 40 knots late in the day. Not expecting any strong storms
given lack of instability but will have to continue to watch.

Overall...a typical Summer day with seasonably warm highs in the
80s along with the risk of a few showers or storms in the
afternoon.

&&

Long term /Saturday night through Thursday/...

Highlights...

* seasonable temperatures and lower humidity for the first half of the week
* pattern change by middle week bringing below average temperatures
* hit or miss showers/thunderstorms through the period

Overview...

00z guidance is in good agreement for most of the period. Issues lie
within the small scale and timing. Strong upper level low will
continue to spin over Hudson Bay keeping the northeast in
southwesterly flow from elongated trough. Several waves will move
through this flow keeping the chance for showers and thunderstorms
in the forecast. Upper level low will begin to shift eastward due to
amplified ridge over the central Continental U.S. And northwesterly low
strengthening. This shift in the pattern will drop heights and temperatures
across the northeast...leading to below average temperatures.

Dailies...

Sunday through Wednesday...moderate confidence.

Middle-level ridge will build across the region Sunday into Monday.
Most of the area should remain dry but cannot rule out a few spot
showers or airmass thunderstorms. Best region will be across
northwest zones due to the higher terrain. Otherwise temperatures
will at or slightly above average. Highs will be near 85f to 90f
with lows between 60-70f.

Potent shortwave will move through the flow on Tuesday. Anticipate
showers and thunderstorms to develop ahead of the wave across
upstate New York on Monday and over southern New England Monday night into Tuesday. Some
modest instability and Li values below -4c leads to the potential
for overnight thunderstorms. Low confidence on strong to severe.

Temperatures on Tuesday will be slightly cooler but still near
seasonable as dry air from the west moves into the area.

Wednesday and beyond...high confidence in temperatures...low confidence in
precipitation.

Closed low aloft will shift eastward pushing a potent shortwave over
the region. This wave will develop a coastal low over the middle-
Atlantic and move close to the benchmark....grazing the South Coast
with precipitation. However exact placement can change...depending on if
pattern amplifies more. Otherwise anticipate cooler conditions as
upper level trough takes hold over the northeast sending several
waves to reinforce the cooler airmass.

&&

Aviation /07z Friday through Tuesday/...
forecaster confidence levels...

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

Short term /through Saturday/...high confidence.

Through 12z...mainly VFR with patchy MVFR and IFR over Cape Cod and
islands including interior valleys in areas of fog.

After 12z...rapid improvement with all terminals VFR. Dry weather
prevails.

Tonight...VFR with low risk of a few showers and MVFR conditions
across western Massachusetts toward daybreak.

Saturday...VFR but scattered showers and possible isolated T-storm
in the afternoon.

Kbos terminal...high confidence in taf. No seabreeze today with
modest west-northwest winds. Some uncertainty on areal coverage of showers
Saturday.

Kbdl terminal...high confidence in taf. Some uncertainty on areal
coverage of showers Saturday.

Outlook /Saturday night through Tuesday/...moderate confidence.

VFR much of the time with a low risk for scattered showers Monday
into Tuesday morning.

&&

Marine...
forecaster confidence levels...

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

Short-term /through Saturday/...high confidence.

Today...T-storms south of Nantucket will continue to move east and
offshore as the morning progresses. Cold front sweeps across the
waters after sunrise with a wind shift from the SW to west. Any
patchy fog quickly improves after sunrise.

Tonight...tranquil dry weather with good visibility and light SW wind.

Saturday...a few showers/T-storms possible especially near shore
and over land.

Outlook /Saturday night through Tuesday/...

Fairly tranquil boating weather this period with modest SW
winds...good visibility and mainly dry weather.

Low risk of scattered showers and T-storms late Monday.

&&

Box watches/warnings/advisories...
CT...none.
Massachusetts...none.
Rhode Island...none.
Marine...Small Craft Advisory until 8 am EDT this morning for anz250-
254>256.

&&

$$
Synopsis...nocera/dunten
near term...nocera
short term...nocera
long term...dunten
aviation...nocera/dunten
marine...nocera/dunten

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