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Area forecast discussion 
National Weather Service Taunton Massachusetts
701 am EDT Tuesday Sep 1 2015

after a weak cold front moves inland today...high pressure once
again regains control into Wednesday. Heat returns Wednesday into
Thursday. Another cold front should bring scattered showers and
thunderstorms Thursday. Then not as warm and noticeably less humid
weather Friday into Sat morning. A warming trend follows for the
Holiday weekend with temperatures well into the 80s to perhaps
near 90 by Sunday and Monday along with dry weather.


Near term /until 7 PM this evening/...

7 am update...

Backdoor front resulting in north-northwest winds this morning that will
eventually turn to the east-NE later this morning and continue into
the afternoon. Thus not as warm along the coast. Lower dew points
advecting into the region with values in the m50s to l60s. Overall
previous forecast capturing these details nicely so no major
changes planned with this update. Earlier discussion below.


Very subtle backdoor cold front is currently sliding in from the
NE early this morning. So subtle in fact it/S barely visible in
thermal fields and requires the mass fields to full appreciate. As
such...the lack of any instability/moisture has allowed mainly
clear skies to dominate across the region.

This will be the expectation with sunrise this morning as
well...plenty of sunshine outside of a few high cirrus. The cooler
airmass associated with the front...combined with onshore flow
across mainly eastern Massachusetts/Rhode Island will yield cooler highs today than
previous days. Temperatures will range from the middle 80s in the CT the upper 70s near the East Coast. Plenty of dry air
should keep the mostly sunny skies in place as strong subsidence
inversion begins to build over through the afternoon and evening


Short term /7 PM this evening through 6 PM Wednesday/...
subsidence inversion continues to build as high pressure regains
control across the region. This will allow middle level temperatures
/particularly around 850 mb/ to approach +20c. Any low level moisture
is likely to become trapped and with increasing dewpoints...light flow
and mainly clear skies could see more widespread fog especially
across western Massachusetts/CT during the early morning hours.

near +20c 850 mb temperatures and plenty of sunshine will lead to one of
the hottest days yet this week. Expect widespread low 90s...with
upper 80s elsewhere. Sea breeze keep S near shore locations a bit
cooler. Noting a slight slackening of mass fields as high pressure
shifts north...but BUFKIT is very dry aloft. While the supports steep
middle level lapse rates and even a very slim corridor of cape
aloft...the dry air and subsidence should cap any daytime/evening
showers/storms. Mainly dry forecast.


Long term /Wednesday night through Monday/...

* scattered T-storms Thursday...otherwise dry weather prevails
* cooler and less humid Thursday night/Friday into Sat morning
* dry with a gradual warming trend for the Holiday weekend

Wednesday night...quiet/dry weather with ridging holding on and associated
deep layer dry air over the region. It will be a warm night after
daytime temperatures Wednesday peak in the u80s and l90s. This combined with dew
points remaining in the 60s will result in mins only falling to 65 to
70...with low 70s in the urban areas. chance for a brief end to our dry weather as middle
level trough moves across the Maritimes and drags a cold front
across southern New England. Best synoptic scale forcing is displaced well east of
New England...however shallow lift/convergence associated with the
front will combine with modest deep layer moisture to yield a risk
for scattered showers/T-storms. Moderate instability with projected
convective available potential energy on the order of 1000-2000j/kg. However limiting factor is lack
of deep layer shear. Thus convection will be difficult to sustain
and this will reduce the threat of strong to severe storms. However
if convective available potential energy can grow to 2000 j/kg or greater instability may compensate
for lack of deep layer shear with the risk of a few storms becoming
strong to perhaps severe. Although weak wind fields aloft suggest
only a low risk of strong storms. Precipitable waters climb to about +1 Standard
deviations greater than climatology. This combined with weak wind fields
aloft may pose a low risk of slow moving storms and associated flood
threat. Otherwise expect another very warm and humid day with highs
85 to 90. So by no means a washout out...a typical late Summer day
with very warm temperatures and a threat of scattered afternoon/evening T-storms.

Thursday night/Friday/Fri night...noticeable airmass change with
cooler and less humid airmass advects into the region Thursday night as
1027 mb Canadian high builds southward through Quebec. In fact could
see NE winds gusts up to 20-25 miles per hour over southeast Massachusetts Friday morning! Although
this backdoor cold front won't have the same punch/cool down as an
early Summer/late Spring event as SSTs in Gulf of ME and eastern Massachusetts
waters are running 65-70! Nevertheless refreshing change Friday into
Sat am as 1027 high builds over the area with dew points in the 50s.
Thus breezy NE winds Friday am will slacken in the afternoon. This will set
the stage for a cool Friday night with mins early Sat morning in the
50s regionwide...except near 60 in the urban areas and along the

Holiday weekend...after a cool/comfortable Sat morning a gradual
warming trend as middle level ridge builds over the area...resulting in
surface ridge sliding south of New England yielding a westerly
surface flow. This west wind should keep humidity in check with dew
points likely remaining in the 50s and only creeping upward toward 60
given downslope component of surface wind. Thus early indications suggest
a dry Holiday weekend with a gradual warming trend.


Aviation /12z Tuesday through Saturday/...
forecaster confidence levels...

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

Short term /through Wednesday/...

7 am update...

No major changes from 06z and 09z taf issuance. Earlier discussion


Through today...high confidence.
VFR. Sea breezes assisted by weak east-NE flow developing across east

Tonight...moderate confidence.
Mainly VFR through the evening...however after midnight some fog
may develop mainly at terminals within and west of the CT valley.
This is where the moderate confidence comes in.

Wednesday...high confidence.
VFR after any fog Burns off.

Kbos terminal...high confidence in taf. Sea breeze timing 13-15z
this morning.

Kbdl terminal...high confidence in taf.

Outlook /Wednesday night through Saturday/...high confidence.

Mainly VFR conditions throughout the period. Low probability of
brief MVFR conditions in scattered rain showers/thunderstorms and rain Thursday. Also...IFR visibilities
possible in patchy fog each night.


forecaster confidence levels...

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

Short term /through Wednesday/...high confidence.

Seas will gradually recede through the day today...such that they
drop mainly below 3 feet across all waters late tonight into Wednesday.
Weak flow through the period. Therefore...mainly quiet boating
weather prevails through Wednesday.

Outlook /Wednesday through Saturday/...high confidence.

Fairly tranquil boating weather this period. The exception will be
late Thursday night into Friday morning when 1027 mb high over Quebec yields
a stiff NE wind of 15 to 20 knots with gusts up to 25 knots possible.
Winds drop off late Friday however low pressure may develop well southeast of Nova
Scotia next weekend. This may result in easterly swells impacting
the eastern Massachusetts waters. Dry weather much of the period with the
exception of scattered T-storms possible Thursday afternoon and evening.


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


near term...nocera/doody
short term...doody
long term...nocera

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