Scientific Forecaster Discussion

Return to Local Conditions & Forecast

Without Abbreviations
With Abbreviations

Area forecast discussion 
National Weather Service Taunton Massachusetts
351 am EDT Wednesday Aug 20 2014

mainly dry weather...except maybe a shower in the west...with
temperatures near or slightly below normal expected through the
weekend. Pattern starts to become a bit more unsettled early next
week with an approaching front.


Near term /until 6 PM this evening/...
some leftover broken-overcast cirrus continues to move east of the region early
this morning...but not before slowing the overnight radiational
cooling process. Therefore...although a few more hours of
potential cooling remain...mins are likely to be a few degrees
warmer across the board than previous nights. So a cool...but not
quite as cool start this morning as Tuesday morning.

Otherwise today...a tale of 3 low pressure centers...two aloft and one
well to the southeast of southern New England. In between inverted ridge of
high pressure is likely to remain in place...assisted by subsidence
between these features. Although a warm front /associated with the
western upper level cutoff sliding east/ will be approaching from the west it
is unlikely to have much of an effect on southern New England. This is
thanks to the subsidence and an already dry column across the
region. However...due note some moisture loading of the column
from the top-down so will likely see some slowly building cloud
cover especially from the Worcester Hills-W.

Temperatures are likely to be bit warmer today as well thanks to a
slightly warmer start and 850 mb temperatures approaching +14c.
Therefore...expect more widespread low-middle 80s than yesterday for
highs. Near shore...sea breezes likely hold temperatures mainly in the


Short term /6 PM this evening through 6 PM Thursday/...
the approaching warm front and gradually opening upper level
cutoff...combined with gradual moisture loading of the column is
likely to lead to more cloud cover across the region than previous
nights. Not out of the question a shower is able to slide across
the west...but both jet and vorticity related dynamics are quite
weak and overall column moisture remains fairly low until the
early morning hours. Therefore...will maintain a mostly dry
forecast except the extreme western fringes of the box County Warning Area through the
overnight hours.

Regarding temperatures...given the increased moisture /cloud
cover/ and warmer evening temperatures expect that overnight lows
will be warmer than previous nights in spite of the near calm flow
once again. More widespread middle 50s with even some normal heat
islands holding in the low-middle 60s are expected.

inverted ridging remains in place...and mainly east-southeast flow expected
across the region. The marine influence is likely to stave off
approaching warm front as it/S attendant upper level cutoff
diminishes to an open wave with cutoff high pressure to the north. Upper
level and low level jets are weak and with overall vorticity
decreasing...therefore dynamic forcing is relatively weak even as
overall column moisture increases through the day /pwats approach
1.75 inches/. Also...with marine flow and warm front trapped to
the unlikely that there will be much destabilization
through the day. Given all of this...the threat for showery
activity remains fairly low. Will focus only low chance probability of precipitation west of
the CT valley...with slight chance probability of precipitation into the Worcester Hills.
Convective activity should dive to the SW of the region where
instability axis resides. Have kept thunder out of the forecast
with this update due to the marine flow and modest lapse rates.
The additional cloud cover and marine flow are also likely to keep
high temperatures cooler than normal /mainly middle 70s/ during the day Thursday.


Long term /Thursday night through Tuesday/...

* quiet weather expected through much of the long term
* uncertainty increases early next week with an approaching front

Rather unique and stable upper level pattern will slowly break down
late this week into this weekend. 20/00z guidance remains in good
agreement through this weekend...then more differences appear early
next week. Will continue to favor a consensus blend to smooth over
the more minor differences.

High pressure in Quebec will keep things relatively dry across most
of southern New England through this weekend. There is potential for
a few showers across the western half of southern New England
Thursday night if some moving parts come together. Moisture is the
main limiting factor...with instability a close second once the sun

This high pressure will sink south through this weekend into early
next week...eventually dropping south of southern New England and
returning US to a more westerly flow. A low pressure in Ontario may
eventually move eastward into Quebec...swinging a cold front through
southern New England sometime Tuesday into Wednesday. Depending on
available moisture...this front may initiate a few showers and


Aviation /07z Wednesday through Sunday/...
forecaster confidence levels...

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

Short term...through Thursday...high confidence.

Mainly VFR through Thursday. Only caveat will be some spotty ground fog
at typically prone airports both this morning and again late
tonight. A few showers possibly mainly west of an ijd-orh-afn line
during the day on Thursday.

Flow shifts from the SW to the east through the day today...assisted
by sea breezes. Light and vrb flow returns again tonight...with east
flow again on Thursday.

Kbos terminal...high confidence in taf.

Kbdl terminal...high confidence in taf.

Outlook...Thursday night through Sunday...

Moderate confidence. Mainly VFR. Low probability of patchy
MVFR/IFR fog each night.


forecaster confidence levels...

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

Short-term...through Thursday...high confidence.

The mainly quiet boating weather continues. Winds remain mainly east
to southeast with a few gusts around 15 knots possible especially across the
outer edge of the S and southeast waters.

Outlook...Thursday night through Sunday...

Moderate to high confidence. Quiet boating weather is expected
through much of this period with high pressure across the region.
Low probability of patchy overnight fog limiting visibilities. Seas
may increase on the outer waters this weekend as an ocean storm
passes well east of the southern New England waters. Wna wave
guidance looks to be too high based on expected winds...lowered this
guidance by 20 percent.


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


near term...doody
short term...doody
long term...Belk

National Weather Service Glossary of Abbreviations