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Area forecast discussion 
National Weather Service Taunton Massachusetts
132 am EST Thursday Mar 5 2015

Synopsis...
a front will stall south of New England overnight. Low pressure
will push along the front with another round of snow overnight into
Thursday...mainly across southern CT...RI...and southeast Massachusetts. High
pressure will build in for Friday through this weekend...bringing
dry conditions with colder than normal temperatures. A weakening
front may bring some light snow showers on Monday. Another cold
front may approach toward the middle of next week.

&&

Near term /until 6 am this morning/...
130 am update...

Cold front has made its way toward the coast and at 1 am stretched
from near Marshfield Massachusetts to Groton CT. Temperatures were slowly
falling behind it...now below freezing in the Berkshires.
However...dewpoints were really falling with readings in the upper
teens and lower 20s ushering in much drier air into northern and
western Massachusetts. Hence the sharp cutoff of precipitation expected on
the northern edge.

Tough forecast because satellite imagery shows a very moist
continuous feed from the Gulf to southern New England. Thus...the
precipitation...which will be changing over to snow by daybreak...
should continue for most of the day today along the South Coast of
Rhode Island and Massachusetts. This could amount to a good deal of snow. But...farther
to the north it now looks like Boston...Worcester..and Springfield
may not receive any snow. New wpc graphic confirms this thinking.

For those wondering about bos snowfall record...we need 1.9
inches to tie 1995-96. Our latest forecast has about 0.7 inches at
bos but this may not even pan out.

&&

Short term /6 am this morning through 6 PM Friday/...
focus for steadier snowfall will be over southeast New England Thursday
morning with rapid drying from northwest bringing clearing to interior by
afternoon. Expect additional 2 to 4 inches during day across S
coastal Rhode Island/Massachusetts and Cape Cod/islands with less than inch as far north as
Mass Pike. Definitely colder day ahead with highs only in 20s
except near 30 on cape and islands.

Clearing sets in across all of region Thursday night as system heads
farther out to sea and high pressure builds in. Another shot of
bitterly cold air arrives with lows from about 5 below to 5 above
across interior to teens closer to coast.

&&

Long term /Friday night through Wednesday/...
* high pressure arrives Friday
* moisture-starved cold front moves through this weekend
* uncertain forecast early next week

Models are in fairly good agreement going into this weekend.
There are some minor discrepancies in timing of a cold front
into this weekend. More significant differences develop Saturday
night into Sunday. The GFS is very aggressive in developing a
surface low near the Great Lakes...and is off on its own in doing
so. At this point...am favoring a consensus blend of the other
guidance due to fairly broad middle-level trough over the northeast.

High pressure south of New England is the main theme early next
week. There is some question as to how close a cold front can get
to southern New England toward middle week.

Friday...a high pressure becomes suppressed to our south as a low
pressure moves into Quebec. This will keep lower temperatures...
well below normal for early March...in place for southern New
England.

This weekend...a shortwave pushes low pressure through Quebec...
allowing a cold front to move through southern New England. At
this point...this frontal passage appears to be fairly moisture-
starved...so little if any precipitation will accompany this front.
Temperatures moderate a bit...but remain well below normal.

Early next week...models continue to show significant differences
with the evolution of the middle level flow. 04/12z GFS is faster to
warm up the lower atmosphere than both its ensemble mean and the
04/12z European model (ecmwf). While thinking temperatures will eventually become
higher...am not yet sold on the GFS timing. This will have
implications for precipitation type. Will continue to favor a
consensus approach for this time range.

&&

Aviation /07z Thursday through Monday/...
forecaster confidence levels...

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

Short term /through Thursday night/...moderate confidence.

Pockets of IFR persist across portions of Cape Cod and the
islands. VFR with isolated MVFR ceilings elsewhere.

MVFR/IFR spreads north in light snow toward daybreak...probably as
far north as kijd-sfz-kpym...mainly due to visibility. Light rain changes to
sleet and snow closer to S coast after 09z where LIFR expected
through daybreak Thursday. VFR ceilings farther north and west. MVFR ceilings also
spreading from the Berkshires into western Massachusetts and western CT
between 06z and 09z.

Conditions slowly improve Thursday from northwest to southeast...with Cape Cod and
islands last to improve 16z-20z.

Expected general snow accumulations...
bos/baf/bdl/bed/orh...little or no snow
pvd...2 inches
fmh/hya...3-4 inches
ack...5-7 inches

Kbos taf...high confidence.

Kbdl taf...high confidence.

Outlook...Friday through Monday...

Moderate confidence. Mainly VFR through this period. Brief MVFR
conditions are possible Saturday nighprevious discussion...

&&

Marine...
forecaster confidence levels...

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

Short term /through Thursday night/...moderate confidence.

Maintaining Small Craft Advisory on outer waters and Block Island/Rhode Island sounds
primarily due to seas through Thursday or Thursday night.

Cold front approaching the coast as of 1 am. It will drops S
overnight with wind shift to northwest and possibly a few gusts to 25 knots.
Spotty light rain will give way to sleet and snow toward daybreak.

Snow should mainly affect S coastal waters Thursday before heading
offshore Thursday night. High pressure building in to region may bring
period of 25kt northwest wind gusts Thursday night...mainly on outer waters.

Outlook...Friday through Monday...

High confidence. Winds and seas slowly diminish Friday as high
pressure builds over the waters. They then increase again...but
only modestly over this weekend as a cold front approaches...then
crosses the waters. Small craft advisories will likely be
necessary on the outer waters for a portion of this time.

&&

Box watches/warnings/advisories...
CT...none.
Massachusetts...Winter Storm Warning until 7 PM EST this evening for maz023-
024.
Winter Weather Advisory until 7 PM EST this evening for
maz020>022.
Rhode Island...Winter Storm Warning until 7 PM EST this evening for riz008.
Winter Weather Advisory until 7 PM EST this evening for
riz003>007.
Marine...Small Craft Advisory until 6 am EST Friday for anz235-237-250-
254>256.

&&

$$
Synopsis...Belk/jwd/gaf
near term...gaf
short term...jwd
long term...Belk
aviation...jwd/gaf
marine...jwd/gaf

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