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Area forecast discussion 
National Weather Service Taunton Massachusetts
326 PM EDT Friday Jul 25 2014

Synopsis...

High pressure nearby will result in dry and beautiful weather into
Saturday afternoon. Scattered showers and thunderstorms expected at
times Sunday into Monday along with a return to the humidity ahead
of the next cold front. The cold front moves offshore Tuesday with
high pressure building in behind.

&&

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

High pressure nearby will result in a beautiful night
across southern New England. Mainly clear skies expected other than
perhaps a bit of high clouds streaming into the region late. The
relatively dry airmass in place and light winds will allow for a
good night of radiational cooling. Lows should bottom out in the
50s across the outlying locations...to the low to middle 60s in the
urban heat islands of downtown Boston/Providence. Low humidity
will make for a very comfortable night.

&&

Short term /6 am Saturday morning through Saturday night/...

Saturday...

A beautiful start to the weekend is on tap for the region. High
pressure moving off the coast will allow for temperatures to be a degree or
two warmer than today. Highs should top out in the middle 80s
across much of the region...with readings a few degrees cooler
across the higher terrain and on the South Coast. While dewpoints
will be several degrees higher...it certainly won't be humid for
July standards. A southwest breeze of 20 to 25 miles per hour expected to
develop during the afternoon.

We will see a mixture of clouds and sunshine...but dry weather will
dominate. Low probability of a spot shower/thunderstorm late in the
afternoon/early evening across the distant interior...but even if it
happens areal coverage/duration should be quite limited.

Saturday night...

Dry weather should dominate for most of the night. An approaching
shortwave from the west along with a burst of elevated instability
should allow scattered showers and thunderstorms to move into our
western zones after 4 or 5 am. It does not appear there will be
enough instability for severe weather...but guess there is a low
probability for a strong thunderstorm or two with MUCAPES on the
order of 500 to 1000 j/kg. Given increasing low level
moisture...low temperatures will be milder than tonight. Low temperatures by
daybreak Sunday should only bottom out in the middle to upper 60s.

&&

Long term /Sunday through Friday/...

* showers and thunderstorms possible over the weekend and into early
next week
* high pressure builds in behind cold front for the second half of
the week

On a synoptic level...the models are in decent agreement...including
the European model (ecmwf) ensemble and gefs. However...there are of course many
discrepancies when it comes to the mesoscale details. The overall
pattern has an anomalously strong persistent upper trough over the
Great Lakes with persistent ridging over the western Continental U.S.. this
brings some timing concerns as the persistent trough is likely to
slow the travel of a cold front expected to move across the region
late Sunday through Tuesday. The main concern for this period of
the forecast will be the Sunday to Tuesday time frame when showers
and thunderstorms are likely. There is a potential for severe
thunderstorms sometime during this time frame but there is quite a
bit of uncertainty when it comes to the details and timing of this
potential. After the cold front moves offshore Tuesday...expect
high pressure to build in across southern New England.

Sunday through Tuesday...low pressure moves through southeastern
Canada with a secondary low developing and moving somewhere close
to...if not over...southern New England. Eventually this system
along with a cold front moves through southern New England.
However...the front does not push offshore until sometime Tuesday or
even Tuesday night. A series of shortwaves rotating around the base
of the upper trough will bring several chances for showers and
thunderstorms to develop. Increasingly warmer and more humid air
will move into the region on southwesterly winds. All of this will
come together resulting in a rather unstable environment with
multiple potential triggers for showers and thunderstorms.

The models stray in the details of course...with the operational
European model (ecmwf) closest to the ensemble means of both the European model (ecmwf) and gefs.
While sb convective available potential energy are forecast to be over 1000 j/kg and 0 to 6 km bulk
shear is forecast to be upwards of 30 to 40 kts during this time...
there are concerns that a quick instability burst early Sunday
morning may result in drier air and subsidence precluding any storms
from developing later Sunday afternoon and evening. However...we
will have to wait and see how things come together Sunday morning
before we can rule out anything happening later Sunday. Storms are
possible again Monday and Tuesday as the front nears and then
crosses into southern New England.

Wednesday through Friday...high pressure builds in over southern New
England Wednesday and slides slowly offshore towards the end of the
work week.

&&

Aviation /19z Friday through Wednesday/...
forecaster confidence levels...

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



Short term /this afternoon through Saturday night/...high confidence
through Saturday evening. Moderate confidence late Saturday night.

Tonight and Saturday...VFR conditions other than very localized
patchy ground fog in the typically prone locations late
tonight/early Saturday morning. Southwest wind gusts of 20 to 25
knots are expected to develop Saturday afternoon...especially on the
eastern New England coast.

Saturday night...VFR conditions during the evening. Some MVFR to
perhaps even localized IFR conditions may develop between 8z and
12z in low clouds/fog patches. In addition...we may see scattered
showers and thunderstorms move in to western New England between 8z
and 12z.

Kbos taf...high confidence. Sea breezes were in the process of
ending as winds were becoming west. Winds should then shift to the
southwest by early evening. High confidence in no sea breeze on
Saturday with southwest wind gusts of 20 to 25 knots expected during
the afternoon.

Kbdl taf...high confidence.

Outlook...Sunday through Wednesday...

Sunday through Tuesday...moderate confidence. Mainly VFR. Periods of
MVFR/IFR likely in shra/tsra.

Wednesday...moderate confidence. VFR.

&&

Marine...
forecaster confidence levels...

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

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

Tonight...high pressure in control will keep winds/seas well below
Small Craft Advisory thresholds. Visibilities will remain excellent.

Saturday...high pressure moving off the coast will result in
south to southwest winds around 15 knots. Gusts to between 20 and
25 knots are expected during the afternoon. The highest wind gusts
are expected near shore. Its marginal and since its 2nd period will
hold off on Small Craft Advisory headlines for now...but the next shift may have to
consider issuance for the near shore waters.

Saturday night... south to southwest winds of 10 to 20 knots will
continue across the waters with high pressure off the coast. Long
south to southwest fetch may allow marginal 5 foot seas to develop
across the southern outer-waters towards 12z Sunday.

Outlook...Sunday through Wednesday...

Moderate confidence. Southwesterly winds and seas increase
gradually as a cold front slowly approaches the waters. Showers and
thunderstorms are possible Sunday through Tuesday over the waters.
Small craft advisories will be necessary Sunday through Tuesday for
seas and Sunday for winds gusting to around 25 kts. Winds and seas
diminish Wednesday as high pressure builds over the waters.

&&

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

&&

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

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