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Area forecast discussion
National Weather Service Taunton Massachusetts
144 am EDT Tue Jul 25 2017

Synopsis...
cool and damp conditions will linger into Tuesday. High
pressure will bring a return to dry and pleasant weather for
Wednesday. Cold front with a surface low pressure wave
approaches southern New England Thursday night and exits the
area late Friday. Dry weather and seasonable temperatures
expected next weekend.

&&

Near term /until 6 am this morning/...
10 PM update...

Nose of the NE low level jet combined with abundant low level
moisture producing areas of drizzle across eastern Massachusetts. Hi-res
guidance suggests at least patchy drizzle will persist into the
overnight hours. Otherwise, lots of low clouds expected and a
few showers from leftover complex in New York may spill into western
MA/CT. Clouds will prevent much diurnal cooling with temps
nearly steady.

&&

Short term /6 am this morning through 6 PM Wednesday/...
a little better start to Tuesday. Despite clouds lingering to
start the day, we should see a drying and clearing trend during
the afternoon, and especially Tuesday night, as a high pressure
arrives from the north.

With winds expected to be more from the north than east, Max
temperatures should be noticeably higher during the day than
Monday, but still below normal. Below normal temperatures
continue Tuesday night.

&&

Long term /Wednesday night through Monday/...
highlights...
* dry weather and seasonable temperatures on Wednesday
* showers and possible thunderstorms late Thu with showers
likely lingering into Fri
* dry weather and seasonable temperatures likely for the weekend

Overview...

Ridge builds over the intermountain west while the eastern
United States looks susceptible to troughing. An anomalously
strong short wave trough for this time of year will cross the
Great Lakes region on Thu and New England on Fri. There is
considerable disagreement between the GFS and European model (ecmwf) operational
runs and ensemble output regarding strength of this short wave
trough. Dry weather should follow in the northwest flow behind the
short wave passage for the weekend when there is much better
consensus among the medium range models. There is also fairly
reasonable model consensus on 850 mb temperatures for the
weekend time period with resultant surface temperatures likely
near seasonable levels. With a few tweaks in the Thu and Fri
period, have gone close to a model consensus for the longer term
forecast period.

Period of focus...Thursday afternoon into Friday

The one period of extra focus in the longer term period covers
Thursday afternoon through Friday when operational and ensemble
model disparities result in somewhat below average confidence on
the outcome. All models depict the short wave trough passage
but vary considerably in strength and some in timing. The European model (ecmwf)
suite of model runs depict a much stronger and as one might
expect slower system than the GFS suite of model runs. Timing
could also play a role in convective potential on the front end
late Thursday afternoon and evening. Have opted to go close to
continuity with pops and just a tad below model consensus due to
model discrepancies. Nevertheless, do believe there will be
enough energy to support likely pops in most areas. Also,
adjusted temperatures down just a little across northern Massachusetts from
a straight model consensus due to a high probability of
cloudiness and at least scattered showers. If the latest European model (ecmwf)
run proves to be correct, then we will probably need to lower
those high temperatures on Friday at least a little more and
raise pops.

As the short wave trough approaches and the 500 mb heights
begin to fall, the air mass becomes marginally unstable late
Thursday, mainly across western and northern Massachusetts and do have a
chance of thunder in the gridded forecast. The slower timing
scenarios, however, would bring the forcing into the region well
past the favorable diurnal time. There is relatively strong
vertical shear as one might expect to be associated with a
robust short wave trough, but the degree of instability remains
something of a question mark. For now, have high chance or low
likely showers and slight chance or chance thunder. We'll be
able to refine this as we get closer.

&&

Aviation /06z 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/...

Through 12z...widespread MVFR/IFR cigs along with patchy fog.
Patchy drizzle across eastern Massachusetts with a few showers moving
across western/central Massachusetts.

Today...moderate confidence. MVFR cigs slowly lifting and
possibly becoming VFR by late in the day. Low risk of a brief
shower.

Tonight...high confidence. VFR with clearing skies overnight.

Wednesday...high confidence. VFR.

Kbos terminal...moderate confidence. MVFR/IFR cigs improving to
MVFR during the morning and lifting to VFR by late in the day.

Kbdl terminal...moderate confidence. MVFR cigs lifting to VFR by
late in the day.

Outlook /Wednesday night through Saturday/...

Wednesday night through Thursday morning...VFR.

Late Thursday afternoon through Friday...MVFR ceilings and
visibilities in areas of showers. Isolated thunderstorms late
Thursday afternoon and evening.

Saturday...VFR.

&&

Marine...
forecaster confidence levels...

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

Short term /through Wednesday/...

Low pressure moves farther away from the waters tonight, backing
winds from northeast to north across most of the waters. Reduced
visibility in rain and fog. Rain diminishes this evening, but fog
and spotty drizzle likely to linger through daybreak Tuesday.

Small Craft Advisory for most waters continues, concluding late
Tuesday into Tuesday night as winds subside and seas diminish.

Outlook /Wednesday night through Saturday/...

Conditions during most of the period will likely remain below
Small Craft Advisory thresholds. However, this is a risk that
winds and seas may approach 25 knots and 5 feet, respectively, in
an increasing SW flow Thursday afternoon and a northerly flow
Friday afternoon and night, depending upon the strength of a low
pressure area that passes across New England and the Gulf of Maine
on Friday.

&&

Tides/coastal flooding...
continued strong NE flow continues tonight with sustained winds
around 10 to 15 mph with gusts upwards of 30 mph. This yields a
surge upwards of a foot for locations along the east Massachusetts coast north of a
low sweeping west to east along the waters south of New England.

A coastal flood advisory continues for the evening high tide
accordingly, given surge on top of high astronomical high tides.

&&

Climate...
here is where we stand for record low maximum temperatures for the
calendar day.

Record Max temperature

Boston 63 - 1904 65
Hartford 67 - 1997 68
Providence 67 - 1997 66 * probable new record
Worcester 60 - 1964 61

&&

Box watches/warnings/advisories...
CT...none.
Massachusetts...coastal flood advisory until 3 am EDT early this morning for
maz007-015-016-019-022-024.
Rhode Island...none.
Marine...Small Craft Advisory until 2 am EDT early this morning for
anz230.
Small Craft Advisory until 2 PM EDT this afternoon for anz231-
251.
Small Craft Advisory until 9 am EDT this morning for anz235-
237.
Small Craft Advisory until 8 PM EDT this evening for anz250.
Small Craft Advisory until 3 am EDT Wednesday for anz254.
Small Craft Advisory until 2 am EDT Wednesday for anz255-256.

&&

$$
Synopsis...Belk/Thompson
near term...kjc
short term...Belk
long term...Thompson

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