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Area forecast discussion 
National Weather Service Taunton Massachusetts
957 am EDT Monday may 25 2015

Synopsis...
a warm front will move across the region today...followed by warm
and muggy conditions lasting into next weekend. The threat for
scattered showers and thunderstorms will increase from late
Wednesday through Thursday and again over the weekend.

&&

Near term /until 6 PM this evening/...
10 am update...

Made updates to the forecast for sky cover as well as wind
gusts...increasing both based on BUFKIT soundings. There remain a
few sprinkles/showers across western and central Massachusetts.
Have adjusted probability of precipitation a bit to account for the trend. As they are
over a fairly data sparse region...not sure if any of the precipitation
is actually reaching the ground at this time. Otherwise...the
forecast is generally on track.

The cloud cover...although present...is not expected to block out
the late-may sunshine. Thus expecting temperatures to climb into
the 80s. 925 mb temperatures hit 17c on Sunday and are forecast to hit
20c this afternoon. Have gone a few degrees higher than guidance.
Exceptions will be on Cape Cod and the islands where it will
remain in the upper 60s and 70s and on the tip of Cape Ann where a
SW to S wind off the cool ocean will likely hold temperatures to
the 70s. Thicker cloud cover could hold temperatures back...but am
thinking that would mainly be over north New England where the better
lift resides.

All models show the gradient tightening up and S/SW winds increasing
to 30-35 knots just above the surface late this afternoon along
the S-coast. BUFKIT shows the potential for a brief period of wind
gusts to 20-28 miles per hour over land areas within an hour or two of 5 PM.
The wind gusts remain less than 20 knots over the coastal waters
due to a pronounced inversion near the surface.

&&

Short term /6 PM this evening through 6 PM Tuesday/...
tonight...SW winds of 10 to 15 miles per hour overnight will help increase
dewpoints to the upper 50s and allow overnight temperatures to
remain in the 60s. A southwesterly low level jet of around 40
knots at 925 mb will be just above the surface but the air should
be decoupled enough to prevent strong wind gusts at the ground.
Could see some patchy fog developing along the South Coast/Cape
Cod/islands. Very slight chance of a shower along the Massachusetts/New Hampshire
border. Again...most of the energy will remain to our north.

Tuesday...S New England remains in increasingly warm and moist
air flow around a Bermuda high pressure system. High clouds in the
morning may thin allowing sunshine for a time. It will be breezy
and very warm. With overnight lows holding in the 60s...it will
not take long for temperatures to zoom into the 80s...maxing out
in the upper 80s especially in the Connecticut and Merrimack
valleys...but still upper 60s and 70s at the South Coast/Cape Cod/
islands. Late in the afternoon...there could be enough instability
in northwest CT and western Massachusetts to pop some scattered thunderstorms.
We have a 20 to 30 percent probability in those areas...but
remaining dry in eastern sections.

&&

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

- warm and muggy conditions
- threat of marine stratus / fog along the S coast
- shower / thunderstorm chances beginning late Wednesday
- threat of heavy rain and possible severe weather
- potential lull in activity Friday
- another round of showers / thunderstorms for the weekend

*/ discussion...

Tuesday night - Wednesday night: ridge of high pressure gradually
deamplifies allowing middle-level energy along with low- to middle-level
SW-convergent flow and rrq of an upper-level jet to slink southeast towards
southern New England. Showers/thunderstorms chances increase. Initial activity looks
to develop across PA / upstate New York by afternoon with daytime heating.
Focus appears to be along a pre-frontal boundary parallel with low-
level Theta-E/instability axes pressing east with the west-southwest steering flow
into north/west New England late into Thursday morning. Likely some severe
to the west. Outcomes uncertain for here. Per BUFKIT capping inversion
along with low- to middle-level dry air lingers. H925-85 SW-flow is
divergent. Shower activity likely pushes east into the forecast area
but loses its punch as it does so. Showers potentially lingering
into the following morning. With anticipated elevated instability
thunderstorm activity not out of the question. Otherwise... warm /
muggy conditions with S-flow of higher dewpoint air north...though middle-
to high-level cloud decks may limit heating. Marine stratus / fog
likely to be an issue for much of the forecast period for S/se-
coastal communities as moisture pools beneath a Stout warm-dry-
subsidence inversion.

Thursday - Thursday night: main driving force of middle-level energy
and attendant jet-streak lifts NE resulting in a cool front pushing
southeast out of Canada to become diffuse into the overnight hours. This in
addition to possible cloud cover left-over from Wednesday puts into
question of shower/thunderstorm development. Though the boundary-
layer may not destabilize...mid-level cooling lending to increased
elevated instability and the suggestion of perhaps some middle- to
upper-level forcing /in addition to the consensus of decent Theta-E
and instability axis across southern New England/ yields continued chance shower /
thunderstorm threat. Decent shear so a severe threat is possible but
have greater confidence towards a heavy rain threat. Precipitable waters in excess
of 1.5-inches with freezing level heights of 11-12 kft. Continuing
with a warm-muggy theme with respect to conditions as well as marine
stratus / fog being an issue along the S/se-coast.

Friday - Friday night: discrepancies among forecast guidance. While
the environment looks prime for shower/thunderstorm development...
not a lot of forcing apparent. Offshore high pressure looks to be
influential as ridging enhances aloft ever slightly ahead of a
weekend disturbance. Biggest discrepancy centers around moisture
availability to which GFS BUFKIT profiles suggest can destabilize.
Will keep with slight chance probability of precipitation for the period.

Weekend - early next week: agreed upon that energy diving S round
the north Canadian vortex meets up with energy out of the central Continental U.S.
Pushing a surface frontal boundary S across the NE Continental U.S.. unclear as
to its evolution...whether it stalls. Forecast into early next week
becomes complicated. Of certainty is that a primed environment looks
to exist ahead of the frontal boundary beneath deep-layer forcing.
This should yield likely shower/thunderstorm activity. But with
timing and longevity uncertain will keep with chance probability of precipitation.

&&

Aviation /14z Monday through Friday/...
forecaster confidence levels...

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

Short term /through Tuesday/...high confidence.

12z update...

Today...VFR. Scattered-broken middle-high level ceilings. Scattered sprinkles across
the west-half of New England. SW winds 10-15 kts may gust to 25 knots
across the interior midday into afternoon.

Tonight...VFR. May see patchy fog with MVFR visibilities late S coast/
Cape Cod/islands. SW winds will be up to 40 knots at 1000-2000 feet
above the surface. Not quite strong enough for low level wind
shear to be inserted into terminals...but important to be aware
of.

Tuesday...VFR. Could still have some patchy MVFR visibilities in fog near
the S coast...mainly early. Chance of a thunderstorm with MVFR visibilities in
northwest CT and western Massachusetts...including bdl/baf and in the Berkshires
late in the afternoon.

Kbos terminal...high confidence in taf.

Kbdl terminal...high confidence in taf.

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

Breezy SW-flow with 20 knots gusts at times. IFR stratus / fog possible
across the S/se-coast. Increasing chances for -shra/thunderstorms and rain beginning
late Wednesday to west...most everywhere Thursday...concluding early
Friday. Tempo MVFR-IFR with any activity.

&&

Marine...
forecaster confidence levels...

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

Short term /through Tuesday/...high confidence.

Today...SW winds...gusting up to 20 knots especially in the late
afternoon. Seas mainly 2 to 4 feet.

Tonight...SW winds increase to 20 to 25 knots. Expecting low level
inversion to prevent stronger winds aloft from making it down to
the sea surface. Seas build to 5-6 feet on the southern waters this
evening and the eastern outer waters overnight. As a result...
a Small Craft Advisory has been issued for these areas through
Tuesday.

Tuesday...gusty SW wind flow of 20 to 25 knots continues over the
outer waters...around the west side of a Bermuda high pressure
system. Have included Nantucket Sound in the Small Craft Advisory
for Tuesday as wind gusts could reach 20 to 25 knots there as well.
A few fog patches with restricted visibility possible on the
southern coastal waters.

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

Persistent SW-fetch with gusts around 20-25 kts at times.
Strongest winds along the near-shore waters. Wave heights in
excess of 5-feet with swell and wind-wave mostly on the outer
waters but getting into the S inner sounds. Dense fog anticipated
lending to visibility restrictions.

&&

Fire weather...
expect dewpoints to slowly but steadily rise into the 50s towards
the end of today. SW winds of 10-20 miles per hour with gusts of 20 to 25 miles per hour
expected...up to 30 miles per hour possible. Forecasted minimum relative humidity values
will be just above 30-percent across the interior...45 to 55 percent
on the South Coast/Cape Cod/islands.

With the increasing humidity...there is a decreased fire weather
risk so will not be issuing a statement at this time.

Although it will be warmer on Tuesday...dewpoints will also be
rising keeping minimum relative humidities from 40 to 50 percent.

&&

Box watches/warnings/advisories...
CT...none.
Massachusetts...none.
Rhode Island...none.
Marine...Small Craft Advisory from 8 am to 6 PM EDT Tuesday for anz232.
Small Craft Advisory from 10 PM this evening to 6 PM EDT
Tuesday for anz235-256.
Small Craft Advisory from 2 am to 6 PM EDT Tuesday for anz250-
254-255.

&&

$$
Synopsis...sipprell/gaf
near term...rlg/sipprell/gaf
short term...sipprell/gaf
long term...gaf
aviation...sipprell/gaf
marine...sipprell/gaf
fire weather...staff

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