Area Forecast Discussion
Issued by NWS Boston, MA

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FXUS61 KBOX 281408
AFDBOX

Area Forecast Discussion
National Weather Service Taunton MA
1008 AM EDT Sun May 28 2017

.SYNOPSIS...

Mainly dry and pleasant weather dominates into tonight, but a
few brief spot showers are possible this afternoon. Low pressure
in the Great Lakes generates a coastal low late Monday that
passes off Nantucket Tuesday. This will bring wet weather for
Memorial Day. Upper low and cold pool linger nearby most of next
week, while surface high pressure builds in. Expect daytime
clouds and scattered showers will pop up each day Tuesday
through Friday. Otherwise fair weather with near seasonable
temperatures.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...

10 am update...

Still an abundance of clouds across southern New England at
mid-late morning, but breaks were beginning to develop. This
was especially true across portions of the eastern MA coast
where skies were partly to mostly sunny.

Overall, should see a scattered to broken deck of mid level
cloudiness persist into the afternoon. However, partial sunshine
is also expected at times. The strong late May sunshine with some
warm advection should allow afternoon highs in many locations
to reach the lower 70s away from the immediate coast. Along the
immediate coast, seas breezes should hold high temps in the 60s.

While dry weather will dominate today, enough diurnal
heating/low level moisture will likely result in a few brief
spot showers. While they can not be ruled out in most locations,
primary area will be western and central MA. Even in these areas
though the vast majority of the day will be dry.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM MONDAY/...
Showers should diminish this evening. Then more widespread
showers start to approach from the west after midnight. Still
appears rainfall is most likely from mid morning into early
afternoon. While an occluded front will not quite make it into
our region, a secondary low pressure should develop and pass
south of New England Monday.

Convective parameters still show a destabilizing airmass at
most layers. Mid level lapse rates remain sufficient to keep a
mention of isolated thunderstorms in the forecast Monday.

&&

.LONG TERM /MONDAY NIGHT THROUGH SATURDAY/...
Highlights...

* Unsettled weather pattern with hit or miss showers.
* Seasonable temperatures through the period with slightly below
  average for the end of the week.
* Hints of a drying trend for the weekend, but confidence is low.

Pattern Details...

The model guidance remains relatively agreeable in showing
persistent upper troughing across the northeast with high
amplitude ridging in the west and northern Plains. The ridge
does diffuse on Friday into Saturday as troughing develops in
Pacific NW which could relax the mass fields/drying trend over
the NE. Still a lot of uncertainty with this outcome.

Temperatures...

Broad upper level trough over the region will keep any summer-
like heat at bay through the period. Generally seasonable
conditions on Tuesday and Wednesday thanks to southwest flow
aloft and thermal ridge. This will result in high temps in the
70s. Depending on how much sun we can generate, cannot rule out
a spot 80 temp on Wednesday due to strong mixing. Mid-level wave
and associated front on Thursday drop temps aloft to well below
average for late May. GEFS indicate this is close to 2 STD below
normal. This will result in cooler than normal temperatures for
Thursday and into Friday. There is the potential that next
Saturday may trend a bit warmer as upper level trough begins
to exit the region. However, the low could linger a bit longer
into next weekend as the EC indicates. Thus low confidence on
the weekend temperatures. Overnight lows will linger in the 50s
through the period.

Precipitation...

Spot shower or two on Monday night as coastal low south of the
region moves eastward. Dry weather for the first half of Tuesday
before another shortwave move through the area during the later
half of the day resulting in showers. Southwest flow aloft
combined with building LLJ ans some elevated instability,
could see some heavy rain and/or thunderstorms during the
evening lasting into the overnight hours.

Multiple disturbances will move through the mean trough as it
settles in across the region through the rest of the work week:
Wednesday through Friday. Very difficult to time disturbances
and resulting precipitation chances. So will mention higher
chances for showers during the more diurnally favored daylight
hours, with slightly lower pops at night. Only day where a
Drying trend could occur is on Thursday thanks to northwest flow
aloft bring in drier air. Still large spread in the guidance
for the weekend so a low confidence.

&&

.AVIATION /14Z SUNDAY THROUGH THURSDAY/...
Forecaster Confidence Levels...

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

Short Term /through Monday/...

10 am update...

Today...High confidence in mainly VFR conditions despite a
scattered to broken deck of mid level cloudiness and a few brief
spot showers this afternoon. Low risk for some brief marginal
MVFR cigs this afternoon.

Tonight...Moderate confidence. Mainly VFR conditions for much
of the night. However, some lower conditions may arrive toward
daybreak Monday especially across the interior depending on the
timing of rain showers.

Monday...Showers move in during the day with isolated thunder.
Cigs and vsbys lower from VFR early to MVFR and areas of IFR in
the afternoon and night. Southeast winds less than 20 knots
except gusts to 25 possible late in the day on the Cape and
Islands. The wet weather diminishes Monday night, but expect
lingering fog/low clouds/drizzle during the night...especially
over Eastern/Central Mass and RI.

KBOS TAF...High confidence in TAF.

KBDL TAF...High confidence in TAF.

Outlook /Monday Night through Thursday/...Moderate confidence.

Monday night into Tuesday...

Lingering IFR in fog/drizzle early in RI and Eastern MA.
Conditions trending to VFR all areas. Potential for brief MVFR
vsbys in scattered showers in the afternoon especially over
Western/Central MA. South winds remain less than 20 knots.
Isolated thunder possible.

Wednesday-Thursday...

VFR. Scattered afternoon showers. Westerly winds with gusts less
than 20 knots.

&&

.MARINE...
Forecaster Confidence Levels...

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

Short Term /through Monday/...

Today and Tonight...High confidence. Weak ridge of high pressure
will keep winds/seas below Small Craft Advisory thresholds.

Monday...High confidence. An approaching low pressure south of
New England will increase the pressure gradient toward daybreak.
Enough southeast fetch may develop across our southwest
outermost waters for some marginal 5 foot seas starting around
12z Monday. It is still too early to hoist any marine headlines
for a marginal 3rd period event.

Outlook /Monday Night through Thursday/...Moderate confidence.

Monday night into Tuesday...

Seas relaxing below 5 feet through the timeframe as NE winds
back to the south. Gusts remain below 20 kts. Vsbys lowered in
showers and iso thunder.

Wednesday through Thursday...

Winds less than 25 knots and seas less than 5 feet through the
period. Scattered afternoon showers possible.

&&

.TIDES/COASTAL FLOODING...
Latest observations show a lingering surge about 0.7-0.9 feet
above normal tides. We did have a few minor coastal flood
reports very early this morning along the eastern MA coast. The
higher of the two high tides today will be around midnight
Monday. As we are even further removed from the highest of the
recent high tides, will let the next shift reevaluate the need
for another Coastal Flood Advisory or Statement. Any coastal
flooding should be minimal.

&&

.BOX WATCHES/WARNINGS/ADVISORIES...
CT...None.
MA...None.
RI...None.
MARINE...None.

&&

$$
SYNOPSIS...Frank/Belk/Dunten
NEAR TERM...Frank
SHORT TERM...Belk
LONG TERM...Dunten
AVIATION...Frank/Dunten
MARINE...Belk/Dunten
TIDES/COASTAL FLOODING...Belk


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