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Area forecast discussion 
National Weather Service Taunton Massachusetts
405 am EDT Wednesday Aug 5 2015

Synopsis...
a few showers or thundershowers are possible this
afternoon...followed by drier weather into Thursday. A period of
unsettled weather is possible Friday into this weekend...but
confidence remains low regarding the timing and coverage of any
potential wet weather.

&&

Near term /until 6 PM this evening/...
convection continues within a band of higher Theta-E/lower static
stability to the S of a weakening cold front currently situated
near the S coast this morning. Bulk of the activity should remain
outside of the box/okx coastal waters due to slight turning toward
the lower stability further S. Even the cirrus/anvil remains offshore.

Otherwise...with cyclonic flow continues across most of New
England today with yet a final strong shortwave expected to move
across the region during the late morning/afternoon hours. This is
within a regime where 500 mb heights are generally 2-3 Standard deviations
below normal and 500 mb temperatures drop between -13c and -15c. Drier air
does continue to invade the column behind the exiting front...so
this limits the lapse rates in spite of the cold temperatures aloft.
Still...looks like enough diurnally driven afternoon instability
to support some modest convective shra/T-storms. The cold temperatures
suggest risk for small hail...but the drier air near the surface could
support some gusty winds as well. Therefore...have added this
wording to the forecast with this update. Highest risk will be
north...where coldest temperatures and overall moisture resides...hence the
marginal risk across northern New England. Therefore...focus is north of
the Mass Pike...but risk is non-zero everywhere. With the dry
air...not expecting activity to be as strong or widespread as
Tuesday...but still Worth watching the skies through the day.

Otherwise...temperatures remain warm today as the coldest air in the low
levels still lags the front a bit. Expect highs mainly in the middle-
upper 80s.

&&

Short term /6 PM this evening through 6 PM Thursday/...
tonight...
suspect any showers/storms will dissipate rather quickly after
sunset...as it will require the surface warming to maintain. Suspect
an end between 00z-02z. With skies clearing and surface pressure gradient
weakening somewhat...temperatures are likely to cool into the 50s by the
early morning hours. Certainly much more comfortable than previous
nights.

Thursday...
weak ridge of high pressure will build across the region. In spite of
last bit of cyclonic curvature aloft...suspect mainly dry
conditions as best lift/moisture remains well to the north. 850 mb temperatures
slightly below normal suggests highs below normal. Mainly the low
80s.

&&

Long term /Thursday night through Tuesday/...
highlights...

* unsettled weather remains possible Friday into the weekend
* temperatures trending below normal through most if not the entire
period

Overview and model preferences...

Noting fairly good agreement with 12z operational models runs into
Friday...then each GOES on their merry own way which lends to low
confidence beyond Friday. One big question will be how the 500 mb cutoff
low across Quebec and Maritimes flattens out...which also flattens
out the flow across most of the northern stream. Depending upon
whether this upper level system flattens out will determine how far
S the large high pressure ridge builds out of central Canada. Also
noting a stalled front S of the region which has a short wave moving
along it...which could push some moisture into portions of southern
New England. Another fly in the ointment is the possible
amplification of long wave trough across the middle Atlantic region this
weekend.

Needless to say...low confidence forecast beyond Friday due to the
wide variance of op model run solutions. Went along with most
available guidance /except GFS/ through Friday...then transitioned
over to an ensemble model blend similar to wpc guidance from
Saturday Onward.

Details...

Thursday...high pressure builds out of central Canada into upstate
New York. Weak short wave moves across northern New England and...with
lack of available moisture in the general west-northwest flow...expect dry
conditions. Highs look to run around 80 degrees...slightly below
seasonal norms.

Thursday night through Saturday...short wave moving along stalled
front from the Ohio Valley. Could start to see some moisture moving
NE into north CT/RI/se Massachusetts overnight Thursday night then push further north during
Friday. Still a lot of question on how far this rain will push into the
region...if at all. For now...kept continuity going from the
previous forecast with mainly chance probability of precipitation...though low likely in
place across S coastal areas Friday into Friday night.

Have lowered probability of precipitation to chance for early Saturday then should push east
during the afternoon into Sat evening.

Sunday through Wednesday...much of this forecast continues to
depend upon the Friday-Sat pattern sets up. At this point...looks like
it should be mainly dry but cool on Sunday. Models signaling another
500 mb long wave trough digging across eastern Great Lakes as 500 mb low
trying to cut off again across Hudson Bay. May see periods of widely
scattered showers from time to time during this timeframe...but low
confidence on timing and placement.

&&

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/...

Through 12z...high confidence.
Mainly VFR and dry. A few low clouds/fog mainly cape/islands.

Today...moderate confidence.
Mainly VFR throughout the day...although some scattered rain showers/thunderstorms and rain with
small hail and gusty winds are possible this afternoon. Not as
widespread as yesterday. West winds with gusts approaching 20 knots at
times.

Tonight into Thursday...high confidence.
Weak high pressure will slowly build across the region. Mainly VFR
conditions expected.

Kbos terminal...high confidence in taf...low confidence in a
shower or storm this afternoon.

Kbdl terminal...high confidence in taf.

Outlook /Thursday night through Sunday/...

Thursday night through Saturday...low confidence on timing...higher
confidence on trends. MVFR-IFR conditions in areas of rain sometime
during this period. VFR before and after periods of rain.

Sunday...low confidence mainly for timing. May see leftover showers
with brief MVFR conditions early...then VFR.

&&

Marine...
forecaster confidence levels...

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

Short-term /through Thursday/...

Through today...moderate confidence.
West winds generally remain below Small Craft Advisory conditions...with seas
gradually receding through the morning. Small craft advisories
remain in place through middle morning along S waters...but will
likely be gone by middle day. A few showers or T-storms possible
mainly near coastlines this afternoon.

Tonight into Thursday...high confidence.
Weak high pressure brings mainly quiet boating weather to the region.

Outlook /Thursday night through Sunday/...

Thursday night...high confidence. Winds and seas below small
craft criteria. Locally reduced visibilities in light rain Thursday night.

Friday through Sunday...moderate confidence. Easterly winds gusting
up to 20 knots. With onshore winds...seas look to build up to 5-6 feet
highest across the eastern outer waters. Rain likely Friday night
through Saturday night...limiting visibilities at times...then
should improve during Sunday.

&&

Box watches/warnings/advisories...
CT...none.
Massachusetts...none.
Rhode Island...none.
Marine...Small Craft Advisory until 11 am EDT this morning for anz235-
237-254>256.

&&

$$
Synopsis...Belk/doody
near term...doody
short term...doody
long term...Belk
aviation...Belk/doody
marine...Belk/doody

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