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Area forecast discussion 
National Weather Service Taunton Massachusetts
1003 PM EDT Friday Mar 27 2015

Synopsis...
a weakening cold front will move across New England this
afternoon...and move farther offshore this evening. A weak low
pressure moving up the coast will bring some light snow to
southern New England tonight and Saturday. High pressure will
push south of New England Sunday. Another batch of precipitation
is possible late Sunday night into Monday ahead of a cold front.
Fast moving low pressure will bring more light rain and/or snow
showers Tuesday night into Wednesday. Low pressure may approach late
next week with more precipitation.

&&

Near term /until 6 am Saturday morning/...

Radar screen is mostly clear. Just some light echoes over southern
Rhode Island and another area streaming northeast across Marthas Vineyard
and Nantucket. Also some light echoes over the Catskills and
Adirondacks.

With the lack of significant echoes at 10 PM...and based on 12z
guidance...the most favorable time for precipitation development will be
late tonight. The 00z hrrr suggests roughly 08z to 12z with focus
on Rhode Island and eastern CT with expansion into mass from Worcester east
to Boston and Taunton by 12z. The favored area will be the central
hills from Worcester to northeast CT.

Based on this we have delayed the onset of probability of precipitation in southern New
England until after midnight overall and most places after 3 am.
Temperatures may be initially too warm for much accumulation.
Overall we are looking at an inch or less from snow showers
overnight.

&&

Short term /6 am Saturday morning through 6 PM Saturday/...
upper trough over the Great Lakes shifts east during this time.
This brings cold advection aloft...further destabilizing the
airmass.

Temperatures marginally favor mainly snow...especially away from
the immediate coast. Temperatures will be crucial to snow
accumulation. Could even see a transition to rain with just a
little upward nudge. Model precipitation amounts have increased
with this latest guidance suite. Thinking 1-3 inches of snow is
more than just a possibility. Do not have enough confidence to
issue a Winter Weather Advisory with this package. However...
would not be surprised to see a few locations exceed that
amount...particularly if the band establishes itself across
central Massachusetts...northeast CT and northwest Rhode Island. These are all
locations with higher terrain. Confidence in the storm total snow
accumulations through Saturday is moderate at best.

&&

Long term /Saturday night through Friday/...
highlights...

* snow showers tapering off during Saturday night
* a weak cold front will move through on Monday bringing scattered showers
* Spring like temperatures move in for Tuesday-Thursday
* Alberta clipper moves through Tuesday night into Wednesday

Overview...
12z model suite and ensembles continue to signal a transition out
of amplified troughing across the eastern U.S. Early this weekend
to a fast moving...active storm track across the northern tier
through the remainder of this forecast period. Temperatures tend
will to moderate over time...getting closer to seasonal norms by
the middle of next week. However...with fast west-northwest flow aloft as 500 mb
ridge builds into western Canada...will see several short waves
in this flow bringing periods of light rain and/or snow showers.
Timing the individual features is tough so this lends to below
average confidence especially toward the end of next week.

500 mb trough moves off the coast along with inverted surface trough
Sat night into Sunday. Northern edge of large high pressure passing
across the middle Atlantic and southeast U.S. Will bring brief drying but temperatures
well below seasonal normals. Beyond this...several short waves
will move across with periods of scattered rain and/or snow showers
through late next week and possibly beyond.

Details...

Saturday night...moderate confidence.
Expect inverted trough sitting across central and eastern areas
to slowly push southeast during the night as offshore low pressure continues
to move away. Light snow will continue through the evening...then
should taper off from northwest-southeast through midnight or so.

As north-NE wind increasing to 10-15 knots with gusts close to 25 knots along
the immediate east Massachusetts coast Sat night along with lingering instability
from the trough...some question as to whether the snow there could
be enhanced by ocean effect as colder air works in over the
relatively milder waters. The 12z NAM /and to a lesser degree the
GFS/ BUFKIT soundings do show steep lapse rates which would signal
ocean effect snowfall. However...ocean waters are at their
coldest levels of the year and...thanks to Arctic air of the last
couple of months...sea surface temperatures are rather low mainly in the
middle to upper 30s in Cape Cod Bay and along the Plymouth County
coastline... ranging to the lower 40s just off the Outer Cape and
Nantucket. When factoring this into the lake effect tool on
BUFKIT...this gives only marginal conditions for the ocean effect.
Not totally ruling out the possibility of brief ocean effect bands
setting up across the Outer Cape...but further west may have a tough
time. Will still need to monitor this feature though.

Overnight lows expected to drop to the upper teens well inland to 25
to 30 along the immediate S coast.

Sunday into Sunday night...high confidence.
Will see dry but cold conditions as high pressure ridge at the
surface and aloft moves across. Clouds will increase from west-east Sun
night as warm air advection aloft pushes in. Highs on Sunday will
remain chilly...only in the upper 30s to lower 40s. Temperatures will
fall back to the 20s early Sun night...then hold steady or rise a
few degrees as clouds move in and SW winds pick up. A few snow
showers might make it into the east slopes of the Berkshires toward
daybreak Monday.

Monday through Tuesday night...moderate confidence.
500 mb short wave moves out of the Great Lakes and quickly pushes
toward the region. May see some widely scattered snow showers as the
precipitation begins Monday morning across central and western areas...then
will change over to scattered rain showers by midday as temperatures recover to
the 40s. This system moves through quickly...with precipitation tapering
off Monday evening. Lows will bottom out in the upper 20s and 30s
Monday night.

Brief respite in between weather systems late Monday night into Tuesday
as weak ridging moves across. Highs on Tuesday will reach the upper
40s to lower 50s...though cooler across the cape and islands.
Another fast moving clipper type system works out of the Great Lakes
later Tuesday...reaching the region Tuesday night. Models having difficulty
with track of the system...though timing is fairly good with precipitation
arriving Tuesday afternoon and continuing into Tuesday night. Not a whole
lot of moisture with this feature so will see scattered light rain showers
which will change over to light snow showers during Tuesday night.
Expect precipitation to taper off across western areas toward daybreak.

Wednesday through Friday...low confidence.
Clipper type system moves offshore Wednesday morning so expect precipitation
to taper off from west-east during the morning. High pressure ridge builds
across for the remainder of Wednesday into Wednesday night. Middle level ridge
also builds east...so will see temperatures closer to seasonal normals on
Wednesday.

High pressure ridge axis will push offshore Thursday night. Timing of next
approaching complex system is very much in question though as 500 mb
trough digs out of the plains states toward the upper Mississippi
Valley into the western Great Lakes. GFS remains more progressive
with this system while ecwmf is slower and more amplified. For
now...introduce chance probability of precipitation for Thursday/Thursday night...then went with only
slight chance probability of precipitation for now on Friday. Rather low confidence during
this portion of the forecast. Still plenty of time to watch this
system.

&&

Aviation /02z Saturday through Wednesday/...
forecaster confidence levels...

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

Short term...tonight and Friday...

Tonight and Saturday...moderate confidence.

Tonight...mainly VFR to start with spotty MVFR-IFR ceilings across
Rhode Island/southeast Massachusetts. Ceilings will lower to MVFR-IFR from S-north 06-08z. Pockets of
IFR-LIFR ceilings/MVFR-IFR visibilities develop around or after 08z...lowest
across east and central Massachusetts/RI/northeast CT. Visibilities will lower as
-shsn breaks out overnight with inverted trough development after
3 am.

Saturday...expect MVFR ceilings across central and western areas and
IFR ceilings across east Massachusetts into Rhode Island during the day. MVFR-IFR ceilings also
prevalent...lowest across east MA/RI. Temperatures should warm into
the 30s which should change the snow to rain in places across the
coastal plain...while the interior remains snow.

Kbos taf...moderate confidence in taf.

Kbdl taf...moderate confidence in taf.

Outlook...Saturday night through Wednesday...
high confidence Saturday night through Monday...then moderate
confidence Monday night through Wednesday.

Saturday night and Sunday morning...VFR conditions likely. Will see
periods of MVFR ceilings/visibilities in scattered snow showers...best chance across
Rhode Island/east Massachusetts. May see brief local IFR conditions across Cape Cod and
Nantucket in any snow bands that may form along the coast. Should
see improving conditions from northwest-southeast from midnight Onward...though
MVFR ceilings may linger on the cape and Nantucket through Sunday
morning.

Sunday afternoon into Sunday night...VFR.

Late Sunday night through Monday night...VFR dropping to local
MVFR ceilings/visibilities in scattered rain showers as cold front moves through.
Conditions improve from west-east Monday night.

Tuesday and Wednesday...VFR through around midday Tuesday...then
local MVFR conditions in developing scattered rain showers Tuesday
afternoon. Precipitation changes to snow showers Tuesday night...then back to
rain showers before tapering off around midday Wednesday with improving
conditions.

&&

Marine...
forecaster confidence levels...

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

Short term...tonight and Saturday...moderate confidence.

North winds pick up as colder air moves south and a disturbance
passes well offshore. Expecting winds gusting to 25 knots on the
eastern outer waters with seas lingering at 5-7 feet. There is
potential for winds gusting to 25 knots on Cape Cod Bay and
Nantucket Sound as well.

Small craft advisories continue for the outer Massachusetts and Rhode Island coastal
waters.

Outlook...Saturday night through Wednesday...

Moderate confidence through Wednesday.

Saturday night...N-NE winds briefly diminish early Sat night then
increase again. Gusts to 25-30 knots across most of the open waters
after midnight. Seas up to 6-8 feet across the outer waters.

Sunday through Monday...expect north winds to shift to SW during
Sunday but will continue to gust to 25-30 knots. Seas remain at or above 5
feet on the open waters.

Monday night-Tuesday...winds shift to west...continue to gust to
25-30 knots highest on the outer waters. Seas remain at or above 5 feet. Winds
may begin to diminish Tuesday night.

Wednesday...expect north-northwest winds to diminish below small craft criteria.
Seas may linger around 5 feet mainly over the southern outer waters
but should subside late in the day.

&&

Box watches/warnings/advisories...
CT...none.
Massachusetts...none.
Rhode Island...none.
Marine...Small Craft Advisory until 6 PM EDT Saturday for anz235-237-
250-254>256.

&&

$$
Synopsis...Belk/evt
near term...wtb
short term...Belk
long term...evt
aviation...Belk/evt
marine...Belk/evt

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