Scientific Forecaster Discussion

Return to Local Conditions & Forecast

Without Abbreviations
With Abbreviations

Area forecast discussion 
National Weather Service Taunton Massachusetts
358 am EDT Thursday Jul 2 2015

a cold front will stalling near the South Coast today...before
moving offshore tonight. Aside from a few showers late today and
tonight over Cape Cod and the islands...and a spot shower near
the South Coast on Saturday...dry weather prevails into early next
week with gradually warming conditions.


Near term /until 6 PM this evening/...
a weak cold front stalls near the coast...but the atmosphere is
fairly dry with limited to no instability. This will result in
mainly some clouds and dry weather. The exception will be towards
Nantucket...where clouds will increase and there is a low risk
for a shower late as some moisture moves north ahead of weak
frontal wave. Local seabreezes will keep temperatures lower along
the coast...where they develop.


Short term /6 PM this evening through 6 PM Friday/...
weak front moves farther offshore tonight as a frontal wave
passes by the benchmark. Majority of the rainfall will stay south
of our region. However...there is a chance of showers toward
Nantucket...with a lower risk of these showers reaching as far
north as Cape Cod...and as far west as The Vineyard.


Long term /Friday night through Wednesday/...

* low chance of a shower on Saturday.
* Gradually warming conditions into early next week.

Overview and model preferences...amplified blocking flow pattern
continues mainly across the eastern Pacific and western Atlantic under
strong ridging...especially in the Pacific where the epo is
forecast to continue to dive strongly negative. This leaves much
of the Continental U.S. In a nearly zonal flow regime. Nearly...because very
weak troughing is evident particularly as northern stream energy moves
shifts through he northern periphery of the mean jet. However...until
about the middle portion of next week...guidance continues to show
southern New England under the influence of the western Atlantic ridging.
So even with the passage of a shortwave this looks to
move through with little fanfare as soundings show dry/subsidence
in place. With moderate agreement between operational GFS/European model (ecmwf)
/some smaller scale differences exist/ a blend will be used
through early next week. Beyond this...there is some significant
uncertainty regarding a shift as the northern stream vortex regains
control across the area...leading to a more unsettled pattern.


Friday night into Sat night...with a weak shortwave moving east from
the Great Lakes and a stalled frontal boundary to the S...will
likely see cyclogenesis of a weak low pressure center well to the S.
This will also introduce ridge of higher Theta-E air which looks
to remain to the west. For now...the best chance looks to remain near
the S coast...closer to the developing low pressure. However...column
remains mostly dry and suggests some influence of the ridge moving
east of the region. So suspect only a few spot showers to contend
with at most. Temperatures at 850 mb are around suspect 2m temperatures
to remain near seasonal normals.

Sun into strong northern stream shortwave continues to deepen
across central Canada...the warm advection will lead to ridge
amplification over the Great Lakes and New England. This will lead
to fairly strong high pressure development which may lock in place for
a few days of dry weather. will be accompanied by
moderating middle level temperatures and rising humidity particularly Monday and
Tuesday. 850 mb temperatures increase to an average of +12c Monday...then closer to
+14c by Tuesday. Therefore...away from coastlines /where sea breezes
will limit warming/ expect temperatures warmer than early July normals.

Middle-late next mentioned above...because this is such a
robust shortwave/cutoff that models are trying to develop...there
is little agreement between them regarding timing/strength...and
ensembles are little help. However...with fairly warm/humid
conditions and an approaching shortwave...there will likely be a
transition to a wetter and more unsettled pattern toward the
latter half of next week.


Aviation /07z Thursday through Monday/...
forecaster confidence levels...

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

Through 12z...high confidence. Mainly VFR. Patchy MVFR/IFR in
developing stratus and fog.

Today...high confidence. VFR most areas. But MVFR ceilings/visibilities may
develop toward kack late...along with the threat of a few showers.

Tonight...moderate confidence. Mainly VFR. Areas of MVFR/IFR
possible Cape Cod and the islands. Showers likely for kack...possibly
reaching the S coast and Cape Cod.

Friday...high confidence. VFR. Sea breezes developing.

Kbos terminal...high confidence in taf.

Kbdl terminal...high confidence in taf.

Outlook...Friday night through Monday...

High confidence. Mainly VFR. Weak sea breezes likely most days.


forecaster confidence levels...

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

Lingering rough seas across portions of the southern coastal
waters will slowly diminish today. So small craft advisories will
persist over these waters for a while longer. Changeable winds as
a cold front first stalls across the waters...then moves farther
offshore tonight. Winds expected to remain less than 15 knots. Once
seas diminish below 5 feet...expecting rather tranquil boating
conditions through Friday. The main issue at that point would be
reduced visibility in scattered showers and patchy fog.

Outlook...Friday night through Monday...

Friday night into Sat...moderate confidence. A week low pressure will
pass well S of the waters. This may lead to east flow reaching
20-25 knots on the southern waters and a building swell which could reach
5-6 feet. Small craft advisories may be needed. Otherwise...some
showers and fog at times may lead to reduced visibilities...mainly on the
southern waters as well.

Sun an Monday...high confidence. High pressure will move over the waters
allowing and remnant swell to subside. After which quiet boating
weather will prevail.


Box watches/warnings/advisories...
Rhode Island...none.
Marine...Small Craft Advisory until 6 PM EDT this evening for anz255-
Small Craft Advisory until 8 am EDT this morning for anz254.
Small Craft Advisory until 2 PM EDT this afternoon for anz235-


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

National Weather Service Glossary of Abbreviations