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fxus61 kbox 171044 
afdbox

Area forecast discussion
National Weather Service Taunton Massachusetts
544 am EST Wed Jan 17 2018

Synopsis...
low pressure will track south of Nantucket today bringing
accumulating snow to much of southern New England today,
heaviest across western and central Massachusetts and northern CT. A
changeover to rain is likely near the South Coast. Mainly dry
weather expected tonight into Sunday, with a warming trend
during this weekend. Another low pressure should affect the
region early next week with mostly rain, but there is a risk of
some snow/mix/ice in the interior.

&&

Near term /until 6 PM this evening/...
* potent winter storm expected today
* hazardous commute expected this morning, mainly across NE,
central and western mass into north central CT

Overview...

1023 hpa low pres continues to develop, located east of Cape May,
New Jersey at 06z per wpc surface analysis. Precip has taken its time
developing across the interior as the first low has been
weakening across upstate NY, but have seen good influx of low
level moisture and lift on the SW flow aloft across S coastal
mass into S Rhode Island and southeast CT since 05z on NE regional 88d radar
imagery. Noting a band of light snow from near Newport to kfmh
and khya at 09z. Also noting increasing radar reflectivities
across west mass into CT. With cooler temps across the interior,
have seen light snow falling from near the mouth of the
Merrimack River southeast to khfd through most of the night, but has
been on the light side. However, have received some spotter
reports up to 2.6 inches of snow in Worthington and 1.8 inches
in Conway, out in western Franklin County. The only caveat is a
dry slot between the two precip areas, which has kept some areas
mainly dry. However, since 08z, the precip is starting to fill
in there as well, so should see snow develop through around 10z.

00z short range models have brought the track of the low back
closer to the coast, though still expected to pass southeast of
Nantucket around midday before heading to the Gulf of Maine as
the open 500 mb long wave trough steadily shifts east. S-southeast winds in
place across Rhode Island/southeast mass today, combined with low level flow
around ridge sitting across eastern Maine and the maritime, will
bring somewhat milder temps. Further inland, temps will remain
close to or a few degrees below freezing through the day.

With the low further offshore, models have trended colder with
the temps. However, the big change on this package is the lower
quantitative precipitation forecast amounts forecasted along with a somewhat later start to the
precip and steady movement offshore during this afternoon. Quantitative precipitation forecast
amounts are about 0.1 to 0.2 inches lower than previous
forecasts, though the band of highest quantitative precipitation forecast remains across NE,
central and west mass.

P-type...

With the colder air remaining across most of the interior as
well as from Cape Ann south to near Boston, will see mainly snow
especially inland where the higher quantitative precipitation forecast values are along with
the better snow growth region. With the onshore wind, milder
surface to 950 hpa temps move in which will cause the mix and
change over to rain across S Rhode Island/southeast mass. Based on this forecast,
looks like the rain/snow line will run close to Route 44 from
about central Plymouth County to Taunton and Providence into east
central CT, but may still see some snow mixed in even down to
the coast and to the lower cape at times. However, this will
hold down snow amounts.

Snow amounts/hazards...

Based on thermal and moisture fields, along with milder air
working into southeast areas, will see lowest amounts across Rhode Island/southeast
mass. Should see some light accumulations even down to the
coast, but could melt away as precip mixes with or changes to
rain. Expect around 1-2 inches there. For north Rhode Island and interior southeast
mass, will see a bit more snow, on the order of 2-4 inches,
highest across interior Providence County Rhode Island.

Across the remainder of the region (n CT/NE, central and west
mass), where the best snow growth is in place as well as
highest quantitative precipitation forecast amounts and coldest temps, will see up 5-8 inches of
snow. Have kept winter storm warnings up from interior Essex
County across through North Worcester and all of Franklin, Hampshire
and Hampden counties. S of there, we converted several zones
over to winter weather advisories covering Cape Ann down to
Boston and into portions of southeast mass, as well as north Rhode Island and north CT.

Will still see some hazardous travel conditions this morning
across interior mass and north central CT as well as along the S
coast.

As the low shifts NE this afternoon, the back edge of the precip
will start to push into the CT valley, allowing the snow and/or
rain to taper off. Winds will also shift to northwest but remain light.

&&

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

The low will push to the Gulf of Maine this evening, so will
see conditions improve from W-E. Last of the precip should be
offshore by around midnight. Another batch of cold air will push
in as skies become mostly clear. May see some northwest winds gusting
up to around 20 kt along the immediate coast.

Expect temps to bottom out mainly in the teens, though will hold
in the 20s along the coast.

Thursday...

As the 500 mb trough moves across the region, will see high
pressure ridging build east. Will see west-northwest winds up to around
10-15 kt, highest along the coast. High temps will only reach
to 25-30 across central and western areas, and the lower 30s
across east mass and Rhode Island.

&&

Long term /Thursday night through Tuesday/...
highlights...

* dry with a warming trend through this weekend
* another storm may bring mostly rain late Monday into Tuesday
with a risk of some interior snow/mixed precip/ice

Quiet pattern expected through the weekend with a moderating
trend as amplified trough moves into the plains with downstream
ridging and rising heights across new eng. Near normal temps
Friday then warming above normal during the weekend with
readings mostly in the 40s.

The aforementioned high amplitude trough is forecast to lift NE
toward new eng early next week with a stormy period sometime
Mon into Tue with decent low level jet moving across the region.
Timing uncertain at this time range but given the amplitude of
the pattern, prefer somewhat slower solution with bulk of the
event occurring Mon night into Tue. Ptype also uncertain across
interior as European model (ecmwf) would suggest some snow/mix/ice with strong
high pres to the N/NE. GFS mostly rain. Will take several days
to resolve these issues.

&&

Aviation /12z 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/...

Today...high confidence in trends. Moderate confidence in
timing.

MVFR-IFR ceilings with local low end VFR ceilings at times. Visibilities
mainly VFR-MVFR, with some IFR visibilities across NE, central and west
mass into north central CT. Conditions should lower to MVFR by mid
morning, with IFR-LIFR at times. Snow mixes with or changes to
rain south of a kghg-kpvd-kwst line by around midday. Will see
change back to snow as precip tapers off and conditions improve
to VFR across CT and western Massachusetts this afternoon.

Tonight...high confidence. Any lingering MVFR-IFR conditions will
improve to VFR across Rhode Island/east mass by around midnight or so. Northwest wind
gusts to around 20 knots around Nantucket and parts of Cape
Cod from midnight Onward.

Thursday...high confidence. VFR. Northwest winds gusting up to 20-25
kt across S coastal areas, Cape Cod and the islands.

Kbos terminal...moderate to high confidence in taf. Expect
continued low conditions during the remainder of the morning
push, though should improve around or after 19z. Ceilings may remain
low through 00z.

Kbdl terminal...high confidence in taf. Morning push will
continue to be impacted. Conditions should start to improve
around midday as precip tapers off.

Outlook /Thursday night through Sunday/...

Thursday night: VFR. Breezy.

Friday: VFR.

Friday night: VFR. Breezy.

Saturday: VFR. Windy with local gusts to 30 kt.

Saturday night: VFR. Breezy.

Sunday: VFR.

&&

Marine...
forecaster confidence levels...

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

Short term /through Thursday/...high confidence.

Today...seas remain at around 5 ft across the outer waters
through midday, then will build again later today and tonight,
up to 6-7 ft. Seas may reach into the waters east of Cape Ann, so
have hoisted small craft advisories there through this
afternoon, then should subside this evening.

Tonight and Thursday...northwest winds will gust up to 20-25 kt,
highest on the southern open waters. Seas will remain around 5
ft, though will subside may briefly subside across portions of
the eastern outer waters. Have extended small craft advisories
through Thursday mainly for the waters from Cape Cod southward.

Outlook /Thursday night through Sunday/...

Thursday night: winds less than 25 kt. Seas up to 5 ft.

Friday: winds less than 25 kt. Areas of seas approaching 5 ft.

Friday night: low risk for Small Craft Advisory winds with
gusts up to 25 kt. Areas of seas approaching 5 ft.

Saturday: moderate risk for Small Craft Advisory winds with
gusts up to 30 kt. Areas of rough seas.

Saturday night: winds less than 25 kt. Local rough seas.

Sunday: winds less than 25 kt. Areas of seas approaching 5 ft.

&&

Hydrology...
445 am update...

A Flood Warning remains in effect for the Connecticut River at
Middle Haddam, where ice jams are causing river fluctuations.

The Flood Warning for at the Taunton river at Bridgewater was
cancelled Monday night as the river level fell below flood
stage.

Cold conditions will persist through midweek which will limit
additional runoff. Continued ice jams will remain on some of
the rivers. There will be some increase of snow pack across
interior southern New England as well.

For details on specific area rivers, including observed and
forecast river stages, please visit the advanced hydrologic
prediction service (ahps) graphs on our website.

&&

Box watches/warnings/advisories...
CT...Winter Weather Advisory until 6 PM EST this evening for ctz004.
Winter Weather Advisory until 3 PM EST this afternoon for
ctz002-003.
Massachusetts...Winter Weather Advisory until 1 PM EST this afternoon for
maz017>019.
Winter Weather Advisory until 6 PM EST this evening for maz007-
013>016.
Winter Storm Warning until 3 PM EST this afternoon for maz002-
003-008>011.
Winter Weather Advisory until 3 PM EST this afternoon for
maz012.
Winter Storm Warning until 6 PM EST this evening for
maz004>006-026.
Rhode Island...Winter Weather Advisory until 1 PM EST this afternoon for
riz002>004.
Winter Weather Advisory until 6 PM EST this evening for riz001.
Marine...Small Craft Advisory until 1 PM EST Thursday for anz250.
Small Craft Advisory from noon today to 6 PM EST this evening
for anz251.
Small Craft Advisory until 6 PM EST Thursday for anz254>256.

&&

$$
Synopsis...kjc/evt
near term...evt
short term...evt

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