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Area forecast discussion 
National Weather Service Taunton Massachusetts
948 PM EDT Monday Jul 27 2015

Synopsis...
a fast moving disturbance will bring a round of scattered showers
and thunderstorms to eastern New England Tuesday afternoon and
evening. Hot and humid Tuesday through Thursday. A cold front may
bring scattered thunderstorms late Thursday and Thursday night.
Warm and dry weather is expected Friday into next weekend.

&&

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

10 PM update...

Radar has quieted down over the past few hours therefor have
lowered probability of precipitation for the first half of the night. Water vapor imagery
showing a shortwave moving down from the Quebec/Ontario line.
Believe this shortwave will trigger a shower or two over the area
with northern New England having the best chance of see more
coverage. Still plenty of instability across the area which could
allow a rumble of thunder within any showers.

Skies are starting to clear out across the CT valley. Since that
region saw a good 1-3 inches of precipitation anticipate it to fog in
overnight do to inversion. Will continue to wait and see when the
fog develops to debate on hoisting a dense fog advection.

Previous discussion...

It looks like much of the overnight hours will be dry. We will
have to watch for the risk for a few spot showers/isolated
thunderstorms developing across eastern New England overnight with
some elevated instability. Low level forcing does not seem as
strong as last night though despite fairly high MUCAPES.
Therefore...just went with low probability of precipitation overnight as much of the
region should end up dry.

The other concern will be for areas of fog to develop overnight.
With rather light winds and wet ground...will have to watch for some
patchy dense fog especially across the interior. That will depend
upon the amount of breaks in the sky cover overnight...but something
later shifts will have to watch closely. Low temperatures will generally
bottom out between 65 and 70.

&&

Short term /6 am Tuesday morning through 6 PM Tuesday/...
***a few strong to severe thunderstorms possible Tuesday afternoon
and early evening along with locally heavy rainfall across eastern
Massachusetts and rhode island***

Tuesday...

Any low clouds and fog patches should burn off by late morning
across the region. Otherwise...expect partly sunny skies to result
in a very warm to even borderline hot afternoon. High temperatures will
top out mainly in the upper 80s to near 90. In addition...it will
be rather humid outside with dewpoints in the 60s and rather light
winds.

Mainly dry weather expected Tuesday morning...but we can not rule
out a spot shower or thunderstorm. The main concern then turns to a
strong piece of shortwave energy that will be dropping south across
the eastern New England coast. Given very warm and humid airmass
with 500 mb temperatures around -10c...we should be able to generate MLCAPE
values on the order of 1500 j/kg. The shortwave combined with the
instability should lead to scattered convection. While an isolated
shower or thunderstorm is possible across the interior...greatest
concern is across eastern Massachusetts and Rhode Island as they will be closer
to the shortwave...but can not completely rule out central Massachusetts.

Will run with scattered showers/thunderstorms mainly across the
eastern half of the region Tuesday afternoon and early evening with
some enhanced wording. As for severe weather potential...low level
wind fields are rather weak which will be a limiting factor.
Nonetheless...strong winds aloft will likely generate 0 to 6 km
shear values of 35 to 45 knots and there is an inverted v look to
the soundings. This means that there is the risk for a few strong
to severe thunderstorms...mainly across eastern Massachusetts and Rhode
Island...but can not rule out central Massachusetts. Locally damaging wind
gusts and hail are the concerns for Tuesday afternoon and early
evening. Highest risk might be along the sea breeze front that sets
up across eastern Massachusetts and Rhode Island as it will provide a focus for
convection. Also...sometimes we end up with some training on these
boundaries and the risk for very localized flooding.

&&

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

* triple-h weather Wednesday/Thursday with highs in 90s.
* Scattered storms Thursday/Thursday night.
* Drier but still very warm Friday through sun.

Overall...good agreement amongst the models on the synoptic pattern.
Upper ridge over the Great Lakes and Ohio Valley slowly weakens as
its pushed eastward by an upper low traveling across the Canadian
prairie. This low will become stationary over Hudson Bay and remain
there through much of the forecast period with the surface
reflection parked just below in about the same location. This will
keep southern New England in southwesterly to westerly surface winds
bringing hot and humid air into the region.

Tuesday night...could see some lingering showers and thunderstorms
into the early part of the night as a front extending from low
pressure in the Maritimes moves offshore. Otherwise...a fairly
humid night with warm temperatures expected to remain in the upper
60s to lower 70s.

Wednesday...another hot...humid...and hazy day expected as the upper
level ridge moves over southern New England. High temperatures are
expected to be in the lower 90s for most locations. With dewpoints
remaining in the upper 60s to lower 70s...heat indices will easily
be in the upper 90s to near 100. Main question for Wednesday will
be whether or not they could reach 100 and heat advisories be needed.

Thursday...a weak front extending from the low pressure in Hudson
Bay will swing through southern New England allowing for a potential
of showers and thunderstorms late in the day into Thursday night.
Decent instability...0-6km shear...and marginal middle level lapse
rates will allow a few of these storms to become strong.

Friday through Sunday...with the synoptic scale pattern fairly
stationary...expect hot and somewhat humid weather to continue
through the weekend. Temperatures will be in the upper 80s to lower
90s.

Monday...another frontal system may bring showers and thunderstorms
to the region.

&&

Aviation /02z Tuesday through Saturday/...
forecaster confidence levels...

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

Short term /through Tuesday afternoon/...

Tonight...low to moderate confidence. Dry weather probably
dominates most locations overnight...a few spot showers or perhaps
a thunderstorm or two can not be ruled out. Otherwise...main
concern overnight will be formation of low clouds and fog. Timing
uncertain...but will have to watch for locally dense fog
developing overnight especially across the interior.

Tuesday...moderate to high confidence. Any low clouds and fog
patches should improve to VFR by late morning. Main concern is
scattered showers/thunderstorms that are expected to develop
generally across eastern Massachusetts/Rhode Island. While activity will be
hit and miss...the potential is there for isolated strong to severe
storms with locally heavy rainfall.

Kbos terminal...high confidence in taf.

Kbdl terminal...moderate confidence in taf. Low clouds and some
fog may develop late tonight.

Outlook /Tuesday night through Saturday/...

Tuesday night...low confidence. Mainly VFR. Low probability of
MVFR/IFR conditions in scattered -shra/thunderstorms and rain across the eastern half of
the area during the early part of the night.

Wednesday...high confidence. VFR.

Thursday...moderate confidence. Mainly VFR except in scattered -shra/tsra.

Friday through Saturday...moderate confidence. VFR.

&&

Marine...
forecaster confidence levels...

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

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

Winds and seas will remain below Small Craft Advisory thresholds
through Tuesday afternoon. A few spot showers and perhaps a
thunderstorm will be possible tonight. However...a better chance of
a few strong to severe thunderstorms Tuesday afternoon which may
result in briefly strong wind gusts and hail. Special marine
warnings may be needed with the highest risk across our waters
adjacent to eastern Massachusetts.



Outlook /Tuesday night through Saturday/...

High confidence. Quiet boating weather is expected through the
period. There may be showers and thunderstorms over the waters
Tuesday night and again Thursday and Thursday night.

&&

Box watches/warnings/advisories...
CT...none.
Massachusetts...none.
Rhode Island...none.
Marine...none.

&&

$$
Synopsis...Frank/rlg
near term...Frank/dunten
short term...Frank
long term...rlg
aviation...Frank/rlg
marine...Frank/rlg

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