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Area forecast discussion 
National Weather Service Taunton Massachusetts
539 am EST Wednesday Mar 4 2015

Synopsis...
weak low pressure will push along the stalled front with another
round of snow tonight into Thursday. 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.

&&

Near term /until 6 PM this evening/...
light rain lingers across S of the Mass Pike early this morning.
Appears another band of rain has developed across north PA/north New Jersey into
NYC area as seen on latest NE regional 88d radar loop. Will see
more light rain across north CT/RI/se Massachusetts. Temperatures will hold above
freezing with the S-SW winds in place ahead of approaching cold
front. Temperatures at 09z running in the middle 30s to lower 40s and will
hold or rise a little bit through midday.

The front will stall S of New England this afternoon as it becomes
parallel to the west-SW upper level flow. Most of the steadier
precipitation should shift to the S coast and islands...though could
still see spotty light rain across areas S of the Mass Pike. Still
a lot of moisture in the middle and upper levels so skies will remain
mainly cloudy especially across southern areas.

&&

Short term /6 PM this evening through 6 PM Thursday/...

Short range models in good agreement on timing...though still
some differences on placement of the stalled front S of New
England. High res models /hrrr...WRF and rap13/ and as well as the
00z NAM and European model (ecmwf) were in good agreement...with the 00z GFS a bit
further north than the other models. Used a non-GFS blend for this
forecast.

Question remains how far north will the moisture from the approaching
surface wave moving along the stalled front will go. Models still
signaling a sharp north cutoff to the precipitation as it moves east-NE
overnight...with the heavier precipitation remaining across S coastal
areas. Kept Cat probability of precipitation going across S Rhode Island/S coastal Massachusetts and the
islands...with likely probability of precipitation across north CT/most of Rhode Island into southeast Massachusetts. Did
keep chance probability of precipitation going to around the Mass Pike then should be
little if any precipitation north of there.

Good slug of precipitation moves east across S coastal areas mainly after
midnight through midday Thursday. Another question will be how quickly
the cold air filters in. Looks like timing is similar to previous
forecast...so expect temperatures falling below freezing after midnight.
So...rain will mix with some sleet before changing over to snow
during tonight. Plus...with periods of moderate snow...will
likely see dynamic cooling late tonight into Thursday morning across S
coastal areas.

Expect total quantitative precipitation forecast tonight and Thursday to range from around 0.1 to 0.2
inches close to the Mass Pike up to 0.5 to 0.8 inches across the S
coast...Cape Cod and the islands. With the colder air working
in...will see a good amount of snowfall...with the best shot
across the islands.

Feel confident that the islands will receive the highest snowfall
from this passing system...so went with a Winter Storm Warning for
those areas. Kept a watch going along the S coast for now as there
is still a chance that they will also see 6+ inches of snow but
still on the fence on this...may also be just below warning
criteria.

Expect steady precipitation to continue through a good portion of Thursday...
though will start to diminish during Thursday afternoon as the low pressure
wave moves by and the upper trough approaches. Precipitation should start
tapering off from NW-se...though will linger across east Rhode Island/southeast Massachusetts
through most of the day.

&&

Long term /Thursday night through Tuesday/...

* high pressure builds in Thursday night...passing S Friday
* moisture starved cold front moves through this weekend
* uncertain forecast early next week

Models are in fairly good agreement going into the weekend. There
are some minor discrepancies in timing of a cold front through the
weekend. Then next week they diverge a bit...with European model (ecmwf) attempting
to bring a coastal low up over the benchmark Tuesday and the GFS
bringing in a strong high pressure just south of southern New
England. At this point...will opt for a blend of available guidance
for the weekend into early next week to take care of some of the
timing errors.

High pressure builds in from the Midwest Thursday night...bringing
an end to the snow. Then Friday...the high pressure becomes
suppressed to the south as low pressure moves into Quebec. This
will keep chilly 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 diverge with radically different solutions
for southern New England. Given the time frame...this is not
completely unusual...so will take either model with a grain of salt
at this time. Regardless of the model...it does look like
temperatures continue to moderate into next week.

&&

Aviation /10z 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/...moderate confidence.

Through 12z...ceilings mainly IFR-LIFR with vlifr along the S coast.
Precipitation ending mainly across the CT valley and north of the Mass Pike
with VFR visibilities...but patchy fog developing with visibilities ranging
from MVFR to IFR with patchy LIFR. S-SW winds at 15-20 knots gusting
to 25 knots mainly across east Massachusetts/Rhode Island where strong low level jet lingers.
Low level wind shear likely at 2kft there. Light rain lingers mainly S of the Mass
Pike.

Today...north of Mass Pike...should see generally VFR conditions. S
of Mass Pike...VFR with patchy MVFR ceilings/visibilities though will see
MVFR-IFR conditions along the S coast with patchy light rain.

Tonight...north of Mass Pike...mainly VFR ceilings though may lower to
MVFR along the Pike after midnight. S of the Mass Pike...
conditions deteriorate to MVFR by 05z in mixed precipitation changing
over to snow from N-S. Will visibilities lower to IFR-LIFR across north
CT/RI/se Massachusetts in periods of snow/+sn after 05z.

Thursday...north of the Mass Pike...VFR. S of the Pike...generally
MVFR-IFR ceilings/visibilities in -sn/snow with local LIFR along the S
coast...Cape Cod and the islands. Will start to see improving ceilings
but IFR ceilings may linger in -sn during the afternoon though will
also begin to improve late in the day.

Kbos taf...high confidence in overall trends...lower confidence in
exact timing.

Kbdl taf...high confidence in overall trends...lower confidence in
exact timing.

Outlook...Thursday night through Sunday...

Moderate confidence. Mainly VFR through this period. Brief MVFR
conditions are possible Thursday night as snow comes to an end.

&&

Marine...
forecaster confidence levels...

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

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

Today...SW winds gusting to 20-25 knots through midday then will
diminish as they shift to west with frontal passage. Expect front to
stall across the southern outer waters or possibly a bit further
S. Small craft advisories may be dropped on the near shore waters
around midday or early afternoon...but look to linger on the
outer waters mainly for high seas.

Tonight and Thursday...winds shift to northwest. Gusts up to 25 knots
mainly on the outer waters tonight. Seas remain at or above 5 feet on the
outer waters as well.

Outlook...Thursday night through Sunday...

High confidence. Winds and seas slowly diminish Thursday night
and Friday as high pressure builds over the waters. They then
increase but only modestly over the 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 from 7 PM this evening to 7 PM EST
Thursday for maz023-024.
Winter Storm Watch from this evening through Thursday evening
for maz020>022.
Rhode Island...Winter Storm Warning from 7 PM this evening to 7 PM EST
Thursday for riz008.
Winter Storm Watch from this evening through Thursday evening
for riz003>007.
Marine...Small Craft Advisory until noon EST today for anz231>234.
Small Craft Advisory until 6 PM EST Thursday for anz235-237-
250-254>256.
Small Craft Advisory until 1 PM EST this afternoon for anz251.

&&

$$
Synopsis...rlg/evt
near term...evt
short term...evt
long term...rlg
aviation...rlg/evt
marine...rlg/evt

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