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Area forecast discussion 
National Weather Service Taunton Massachusetts
703 am EDT Monday Aug 3 2015

Synopsis...
dry weather prevails much of today then the threat of showers and
thunderstorms returns this evening into Tuesday. Dry...warm and less
humid weather arrives Wednesday and continues into Thursday. A
period of unsettled weather is possible Thursday night into
Saturday...but confidence is low on the timing of potential wet
weather.

&&

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

700 am update...

Overall trend in the forecast remains on track for this morning.
Showers have develops south of Nantucket this morning in wake of a
strengthening upper level jet and increasing 925 mb moisture.
Showers will continue throughout the morning and into the
afternoon as jet continues to strengthen.

Otherwise fog has developed over the past hour across low lying
regions. This will dissipate within the hour as temperatures begin to
soar into the upper 80s to low 90s. Stratus will also break up
within the hour so am not anticipating much impact on terminals.



Previous discussion...

Quite the convective complex early this morning over the Ohio Valley.
Models appear to be simulating this convection fairly well so
forecast confidence is high regarding today/S forecast for southern
New England. Good model agreement that lead short wave over the
Great Lakes will eject northeast into western New York state today and
then into northern Vermont and St lwrn River Valley thereafter. This results
in little if any height falls across southern New England today.
Thus should be enough East Coast ridging and associated middle level
dry air to preclude any storms from forming or tracking into the
area. The one exception is across western Massachusetts...closer to the jet
energy/moisture and instability axis. Therefore there is a low risk
for a few storms late in the day to possibly clip western Massachusetts.
Otherwise remainder of the region should remain dry.

South-southwest low level flow has resulted in dew points rising
overnight into the 60s to around 70 across Rhode Island and southeast Massachusetts.
Thus more humid than yesterday. Weak low level warm air advection
will result in temperatures making a run at 90 away from the South Coast.
Therefore most locations will see highs today 85 to 90. An
increasing south-southwest wind of 15 to 20 miles per hour with gusts up to 25 miles per hour this
afternoon will help take some of the edge off the warm and humid
conditions.

&&

Short term /6 PM this evening through 6 PM Tuesday/...
*** possible strong to severe T-storms later tonight into Tuesday ***

Tonight...

More potent trailing short wave trough approaches southern New
England from the west. This is quite evident in wind fields aloft
where 500 mb speeds approach 50 kts! This short wave trough cools 500 mb
temperatures to -11c/-12c. This combined with surface dew points increasing
into the u60s and l70s provides MUCAPES greater than 2000j/kg and
middle level lapse rates between 6.5 and 7.0c/km by 12z Tuesday across Rhode Island
and eastern Massachusetts per 00z ec and 00z GFS! Even the course 00z gefs has
the same signal and strength. This amount of instability combined
with deep layer shear up to 50 knots provides an environment favorable
for severe storms. Only uncertainty is will there be enough forcing
for ascent to unleash this strong instability. Mixed signals within
the guidance with the GFS and European model (ecmwf) not generating much quantitative precipitation forecast tonight
while the hi res guidance nmm and arw have convection but weakening as
it crosses the area from west to east. Somewhat discounting the NAM
given it/S high biased dew points and corresponding instability
parameters.

Thus low forecast confidence on areal coverage and intensity of
convection. However if storms can fire strong to damaging winds will
be a concern. Low level shear is impressive too along with
sufficient instability and low LCLs /high dew points/ for a low risk of
an isolated tornado.

It will be a warm and humid night with dew points rising through the
u60s and l70s.

Tuesday...

Forecast uncertainty continues as areal coverage of nocturnal
convection and cloud debris from tonight will impact if new
convection fires during the day Tuesday. Short wave trough moves across
the area along with attending surface trough. This should provide
enough forcing for ascent to initiate convection. Deep layer
moisture and instability appears to be focused across Rhode Island and eastern
Massachusetts. Thus risk of storms greatest across this area. Winds fields
remain impressive so risk of strong to damaging winds continues.

Another warm day with highs well into the 80s along with dew points in
the u60s to l70s.

&&

Long term /Tuesday night through Sunday/...
highlights...

* unsettled weather possible around Friday
* temperatures trending below normal during this period

Overview...

00z guidance is in descent agreement for this portion of the
forecast. Upper level low over James Bay will begin its eastward
movement towards the Maritimes. Elongated trough will set up over
the region before trending towards a zonal flow. Several southern
stream waves will move through and tries to bring a few coastal
systems towards southern New England. The pattern does not seem that amplified to
make it a classic coastal low...however upper level jet may bring a
few systems just south of the region. Because of the uncertainty at
the end of the week...trended towards the ensembles which indicate
precipitation around late Thursday into Friday and again possible
Saturday/Sunday. This unseasonable pattern will lead to below normal
temperatures toward the end of the week into the weekend.

Dailies...

Wednesday into Thursday...moderate confidence.

A few lingering showers and thunderstorms over the waters as cold
front passes through late Tuesday night.

Shortwave will push through on Wednesday as high pressure builds in
from the west. Upper level trough will allow for cyclonic flow and
cold air aloft...resulting in a few afternoon instability showers
across the higher terrain. Otherwise it will be a mix of clouds and
sunshine.

Cyclonic flow will still be aloft by Thursday but cold air aloft
will be focus more across northern New England. Therefore believe
Thursday will be dry with a mix of sun and clouds.

Temperatures will be cooler than normal both days with southern New England reaching
into the 80s on wednesdays but below 80 on Thursday.

Thursday night into Friday...moderate confidence.

Potent shortwave will try to develop a southern wave during the end
of the work week. Both ensemble members as well as the operations
ec brings precipitation to the region during this time frame. Therefore
have increased precipitation chances across the South Coast where
confidence is highest. Southern New England will be on the northern side of this
system so any shift in the pattern will move the precipitation chance for the
region. Finally being on the north-side of the system...temperatures
will be unseasonable cooler. In fact temperatures will struggle to
get above 80f.

Saturday and beyond...moderate confidence.

Another southern stream wave tries to develop over the weekend. Low
confidence on if the pattern will bring this low to southern New England. Have kept a
low chance as guidance continues to flip-flop during the timeframe.
Otherwise...temperatures will begin to moderate over the weekend
into next week as upper level ridge over the Continental U.S. Begins to build
again.

&&

Aviation /12z Monday through Friday/...
forecaster confidence levels...

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

Today...VFR and dry weather for most terminals. Patchy IFR in fog
and stratus will burn off within the hour. Also T-storms in New York
state this afternoon may clip western Massachusetts late in the day. South-southwest
winds increase this afternoon with gusts up to 20-25 knots possible.
Moderate to high forecast confidence.

Tonight...lots of uncertainty on areal coverage and intensity of
potential T-storms. Thus low confidence forecast here. VFR to
start but lowering to MVFR and probably IFR in low clouds and fog
across Rhode Island and southeast Massachusetts.

Tuesday...lots of uncertainty on areal coverage and intensity of
potential T-storms. Thus low confidence forecast here. A mix of
MVFR and IFR in the morning as low clouds and fog impact the
terminals. Likely improving to VFR in the afternoon.

Kbos terminal...high confidence in taf today then lowering tonight
and Tuesday.

Kbdl terminal...high confidence in taf today then lowering tonight
and Tuesday.

Outlook /Tuesday night through Friday/...

Wednesday...moderate confidence. Mainly VFR. Could see MVFR in
showers across higher terrain.

Thursday into Friday...low confidence. A period of showers and
MVFR/IFR possible but timing is uncertain. Latest indications are
that best chance for wet weather will be on Friday.

&&

Marine...
forecaster confidence levels...

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

Short-term /through Monday night/...

Today...

South-southwest winds increase to 15 to 20 knots with gusts up to 25 knots. Seas
increase especially across the south coastal waters. Patchy fog and
drizzle impact the south waters this morning. Improving this
afternoon. Moderate to high confidence.

Tonight...

South-southwest winds 15 to 20 knots. Gusts up to 25 knots possible. Patchy fog will
limit visibility. A few strong T-storms possible especially after
midnight. Low confidence on T-storm forecast.

Tuesday...

South-southwest winds 15 to 20 knots with gusts up to 25 knots possible. Patchy
morning fog may reduce visibility. A few strong T-storms possible. Low
confidence on T-storm forecast.

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

Wednesday...moderate confidence. West/SW winds below Small Craft Advisory but gusts to
20 knots possible. Seas subsiding.

Thursday into Friday...low confidence. Winds and seas will depend on
track and timing of low pressure approaching the region. Could see a
period of gusty NE winds...especially Friday.

&&

Box watches/warnings/advisories...
CT...none.
Massachusetts...none.
Rhode Island...none.
Marine...Small Craft Advisory from 4 PM this afternoon to 8 PM EDT
Tuesday for anz230>237-250-251-254>256.

&&

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

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