Scientific Forecaster Discussion

Return to Local Conditions & Forecast

Without Abbreviations
With Abbreviations

Area forecast discussion 
National Weather Service Taunton Massachusetts
157 PM EDT Sat Aug 30 2014

high pressure over New England moves offshore today. Warmer and
more humid air will then move up from the south with summertime
humidity starting Sunday. A front will slowly push across New
England through Monday bringing a period of showers and scattered
thunderstorms. Another fast moving front may bring a few more
showers and thunderstorms Tuesday...mainly across the interior.
High pressure takes over late next week with dry and warm


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

2 PM update...

Pleasant afternoon in progress with temperatures in the 70s along with
comfortable humidity as dew points remain in the 50s...despite a
southerly wind of 10-20 miles per hour. Strato-cumulus is more abundant in the CT
River Valley but still some breaks of sunshine occurring there. Not
much change to forecast as these details are already captured in
the previous forecast.


Short term /7 PM this evening through 6 PM Sunday/...

with high pressure offshore...south winds will bring warmer more
humid air toward New England. This will mean increasing clouds as
the higher humidity air rides up over the cooler airmass at the
surface. The moist layer will be concentrated below 950 mb with
at best weak expect clouds and fog with some drizzle

shortwave moving through the upper flow will start the day over
the Great Lakes. An 85-90 knot jet will drive the system east into
New England by later in the day. The dynamically favorable zones
for lift associated with the jet will be well to our west in the
morning...but then shift into our area during the afternoon with
the best support in western mass/southern New Hampshire late in the day.

Clouds may thin in the morning but should thicken again through
the day as shortwave and its deeper moisture move in. Lapse rate
in the 850-500 mb layer is so-so at 5.5c/km. Totals climb to the
middle 40s. Winds at 850 mb reach 30 knots while 500 mb winds reach
40-45 knots. Precipitable water values will climb through the day
with afternoon values of 2.0 to 2.25 inches...move than 2 Standard
deviations above normal and potentially near 3.

This favors showers and scattered thunderstorms with potential for
strong wind gusts and heavy downpours.


Long term /Sunday night through Friday/...
overview and model preferences...
medium range models and their ensembles continue to show pretty
good continuity with this forecast package...though some timing
differences work in beginning around the Tuesday timeframe through
the remainder of next week as the flat upper level wind flow
across the northern tier states tending to cause operational model
runs to exacerbate timing issues with fast moving systems in this

Upper level pattern for this portion of the forecast starts off
with rather high amplitude ridge from the northeast into Quebec in
the northern stream wind flow...while a trough digs out of the
northern plains. Overall...this northern stream has been generally
flatter than the last several months /with high amplitude slow
moving patterns/...which signals a faster flow of surface systems
within this flow. Early in this forecast...will see a short wave
ride across in the flatter portion of the ridge across the
region... which will keep unsettled conditions into the Holiday.
Once this moves east...expect a somewhat amplified but progressive
pattern through the remainder of next week. One thing that is
consistent is a continued milder than normal temperature regime
with rather high humidity to start off...then will slowly drop but
remain somewhat uncomfortable...our shot for late Summer

Leaned toward a blend of available guidance into early Tuesday as
a pretty good consensus continues. From later Tuesday through the
end of next week...transitioned over to the ensemble means which
have been more stable than the operational model runs due to
timing issues with the fast flow aloft. Have lower confidence in
the forecast beyond early Tuesday.


Sunday night through Monday night...
expect showers and some thunderstorms to continue through most of
this timeframe as an upper level feature and surface reflection
remains parallel to the SW upper flow. As the flow flattens out
late Monday into Monday night...the leftover energy will shift offshore
but may linger across southern areas.

Models continue to signal high precipitable waters ...on order of 2.2 to 2.3 some rainfall may be heavy at times especially in any
thunderstorms. Antecedent conditions have been pretty dry over the
last several weeks...except for a few spots that did have some
locally heavy rainfall around 8/27-28 /central Massachusetts and S central
CT/. There may be a few localized areas that are prone to poor
drainage flooding that might have some problems Sun night into Monday
morning...but only a low probability for this. Also noting 850 mb
winds up to 35-40 some could mix down with any storms
early Sun night across the interior.

Should start to see improving conditions across S New Hampshire/north Massachusetts early
Monday night...then will shift southward overnight. Only question
will be timing the precipitation exit along the S coast...which it may
linger a bit longer. Should see this area improve around or after

Expect warm and humid conditions with S-SW winds in place. Dewpoints
will be the 65 to 70 degree range...though may drop a
bit inland as conditions improve Monday night.

Tuesday and Tuesday night...
another front will quickly push toward the region. Will see
another round of scattered showers mainly across the interior where the
best energy and dynamics occur. Can not rule out a couple of
thunderstorms as well. Should see improving conditions after
leftover showers will lift NE Tuesday night.

Warm and humid conditions will continue with highs in the Lower-
Middle 80s. It will remain sticky Tuesday night...though dewpoints may drop
a few degrees well inland.

Wednesday through Friday...
high pressure will move across the region through most of this
timeframe. With continued west-SW winds in place...temperatures will remain
several degrees warmer than seasonal norms for early September. Does
look like dewpoints will be a bit more comfortable on Thursday...
forecast in the middle 50s to around 60 /vs. 65 to 70 early in the
week/. Highs will continue in the Lower-Middle 80s.

May see another front try to approach later Friday...though
timing is in question. Have kept a dry forecast during the day for
now...but might see some showers try to move in Friday night. Lower
confidence on this portion of the forecast.


Aviation /18z Saturday through Thursday/...
forecaster confidence levels...

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

Short term /thru Sunday night/...high confidence in trends but
lower confidence in precise details and timing.

Through 00z...VFR with ceilings bkn040-050...less clouds eastern Massachusetts and
Rhode Island. S to southeast winds 10-20 knots

After 00z...VFR to start then lowering to MVFR ceilings beginning
03z-06z followed by MVFR visibilities later in patchy fog.

Sunday...marginal MVFR-VFR. Rain showers and thunderstorms and rain developing after 18z
west and then sliding east toward 00z. Activity most widespread
across northwest CT-Massachusetts into southwest New Hampshire. A few strong storms
possible with torrential downpours and gusty winds possible.

Sunday night...MVFR during the evening slipping to IFR. Rain showers and
thunderstorms and rain especially during the evening. A few strong storms possible
with heavy rainfall and gusty wind.

Kbos terminal...high confidence in taf regarding trends but lower
confidence on precise details and timing.

Kbdl terminal...high confidence in taf regarding trends but lower
confidence on precise details and timing.

Outlook...Monday through Wednesday...

Monday...low confidence.

Low end VFR generally...though will see pockets of MVFR-IFR
ceilings/visibilities in areas of showers. Possible thunderstorms and rain at some terminals
especially inland early Sun night. S-SW winds continue. Patchy
fog develops with MVFR-IFR visibilities late Sun night into Monday morning.

Tuesday...moderate confidence.

Another front pushes across the region Tuesday night. Mainly low end
VFR conditions. Scattered showers across the interior Tuesday
afternoon/early Tuesday night...then should lift NE. Low risk for
thunderstorms and rain. Winds veer to west late Tuesday night. May see patchy fog after
midnight in normally prone valley areas.

Wednesday...moderate confidence.

Mainly VFR. Patchy fog early Wednesday morning with local MVFR-IFR
visibilities will improve by middle morning.


forecaster confidence levels...

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

Today...high pressure over the waters will mean fair skies and
light south winds. Some patchy fog possible around sunrise.

warm humid air moves up from the south and across the waters. This
would favor patchy fog and possibly light drizzle.

Sunday...increasing southwest wind with gusts 20-22 knots.
Building seas...but heights below 5 feet until evening.
Showers/thunderstorms will develop west and northwest of Massachusetts.
There is a low end chance these could reach the waters late Sunday
with heavy downpours and strong wind gusts.

Outlook...Sunday night through Wednesday...

Sunday night and Monday...moderate confidence.

S-SW winds gusting up to 20 knots. May see a few gusts close to 25
knots on the outer waters Sun night. Seas build to around 5 feet mainly
on the southern outer waters. May see patchy fog develop late Sun
night into Monday morning.

Tuesday and Wednesday...moderate confidence.

Expect winds and seas below small craft criteria. SW winds will
veer to west late Tuesday night into Wednesday.


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


near term...nocera
short term...wtb
long term...evt

National Weather Service Glossary of Abbreviations