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Area forecast discussion 
National Weather Service Taunton Massachusetts
700 PM EDT Wednesday Jul 30 2014

mainly dry/pleasant weather today other than perhaps a brief passing
sprinkle. A few showers and perhaps a thunderstorm or two are
possible Thursday and Friday...but most of the time will feature dry
weather. Confidence is increasing in a period of steady rain
sometime this weekend as low pressure tracks close to the coast.


Near term /until 6 am Thursday morning/...

700 PM update...
dry weather trend will continue over the next 12 hours as weak
high pressure remains overhead. Temperatures will drop quickly tonight
after sunset as light winds and clear skies will allow for
radiational heating. However cloud debris from upstate New York
may limit this in the latter half of the overnight hours.
Otherwise patchy fog in the normal prone region across the
interior may develop limiting visibilities. Aside from a few changes the
overall trends in the forecast remain on track.


Short term /6 am Thursday morning through Thursday night/...
a potent shortwave will be moving into northern New England Thursday.
Marginal instability will develop across our northern and western
zones...with convective available potential energy on the order of 500 to 1000 j/kg. 0 to 6 km
shear is fairly strong...around 40 knots. The core of the 500 mb
cold pool temperatures around -18 to -20c...which is quite cold
for this time of year.

The best dynamics will be to our north and west. However...enough
parameters are in place for a few hit or miss showers or
thunderstorms across the interior...especially across northwest Massachusetts
and southwest New Hampshire. While instability is rather marginal...the cold
pool aloft and robust shear may result in a few strong storms
producing small hail and/or gusty winds.

Instability weakens Thursday showers and thunderstorm
coverage decreases through the evening.


Long term /Friday through Wednesday/...

* an isolated thunderstorm is possible on Friday
* very unsettled pattern for the weekend
* showers and thunderstorms possible early next week

Models and confidence...

12z model guidance is still in good agreement with the forecast. A
strong trough will dominate across the Midwest for the remainder of
this week into the weekend. A stalled front over the eastern
Seaboard will be the focus for heavy rain for the weekend as several
waves ride along this front. Out upper level ridge will
continue to build across the western Continental U.S. And eventually move into
the plains. This will allow for the upper level trough to turn more
zonal by the first half of the week. Because of the overall
agreement trended towards a blend of the models and previous
forecast for this package. For confidence level...have high
confidence on trends for this forecast...but a low confidence on
exact timing.



Southwesterly flow will allow for Gulf moisture to begin to seep
into the region by Friday. Temperatures will be close to average
with a mixture of clouds and sun. Models try to push out some quantitative precipitation forecast
but do not have a good feeling as high pressure out east build
allowing for an increase in heights. In fact some of the instability
parameters move westward throughout the day. So for now mentioned
just isolated thunderstorms...but with a lower confidence.

Saturday into Sunday...

Main focus on the forecast was focus on the weekend. Guidance
continues to show that a slug of rain will impact New England
sometime during the weekend...but there is still some differences in
timing. Overall a stalled front will be draped across the eastern
sea board as a few waves ride along this front bring unsettled
weather to the region. Appears to be 2 different model camps...the
GFS/Canadian and the ec/ecens/UKMET. The GFS Camp brings the
heaviest rain on Sunday while the ec Camp brings it in during the
day on Saturday. Overall uniform southwesterly flow through The
Levels will allow for the flow to tap into the Gulf moisture
increasing the precipitable waters close to 2 inches...and almost 2 Standard
deviations away. Both models are also showing a good 850 mb low level jet into
the flow at respective times for heavy rain to occur. Also because
of the increasing low level jet cannot rule out a rumble of thunder.
Confidence is moderate to high that heavier rain will occur...just a
matter of fine tuning the timing of when it will impact southern New

Work week...

Upper level flow will become more zonal by the beginning of the work
week. However appears that there may be some lingering showers on
Monday...with a better shot on Tuesday as front slides through the
region. However timing of this system may change as it is still 6-7
days away.


Aviation /00z Thursday through Monday/...
forecaster confidence levels...

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

Short through Thursday...

Through 02z...high confidence. VFR. Sea breezes should begin to
dissipate...uncertain on the timing.

Tonight and Thursday...high confidence. Patchy late night low
clouds and fog with local IFR possible. Mainly VFR conditions. A
few hit and miss showers/thunderstorms are expected during the day
Thursday across the interior...which may result in briefly lower

Thursday night...moderate confidence. Mainly VFR...with local IFR
in low clouds and patchy fog.

Kbos taf...high confidence in taf. Moderate confidence in end
time of sea breeze this evening.

Kbdl taf...high confidence in taf.

Outlook...Friday through Sunday...

Friday...high confidence. Mainly VFR. Low probability of a brief
period of MVFR conditions in -shra.

Saturday and Sunday...moderate confidence. MVFR ceilings/visibilities in
scattered showers. Possible MVFR/IFR conditions more probable towards
eastern Massachusetts/Rhode Island in -ra and isolated thunder.

Monday...moderate confidence. Conditions improving to VFR.


forecaster confidence levels...

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

Short through Thursday night...

High confidence. Winds/seas should generally remain below Small
Craft Advisory levels through Thursday night along with good
visibilities. Low risk of marginal 5 foot swell reaching into the
southern and eastern Atlantic waters tonight and Thursday from a
distant offshore low pressure. Based on most wave guidance...
capped seas at 4 feet for now but later shifts will have to

Outlook...Friday through Monday...

Friday...high confidence. Quiet boating weather expected with high
pressure over the waters.

Saturday and Sunday...moderate confidence. Winds and seas are
forecast to remain below Small Craft Advisory criteria.
However...more unsettled weather is likely with a stationary front
wavering over the waters. Bring several rounds of rain and isolated

Monday...moderate confidence. Improving visibility conditions with
seas/winds still below Small Craft Advisory.


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


near term...Belk/dunten
short term...Belk
long term...dunten

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