Area Forecast Discussion
Issued by NWS Boston, MA

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FXUS61 KBOX 271352

Area Forecast Discussion
National Weather Service Taunton MA
952 AM EDT Thu Oct 27 2016

Low pressure approaches from the west, with snow developing across
western portions of MA and CT by late morning. Elsewhere rain
heavy at times this afternoon and tonight along with gusty winds
at the coast. Drying trend Friday but becoming breezy behind
departing low pressure. A cold front may bring a few showers to
the region Sat afternoon and evening. Low pressure may form on
this front and bring the risk for a period of rain to the area
Sunday. Dry much of next week with temperatures cool Monday but
becoming mild Tue and Wed.


10 AM Update...No major changes to the forecast this morning.
Appears to be right on track for most elements. Did adjust PoPs
slightly to bring the higher PoPs into the western zones a bit
faster, with snow already falling in portions of southern

7 AM Update...

Regarding snow potential this afternoon NAM/SREF AND NCAR
ensembles have a fairly high probs from 18z-21z for a brief period
of accumulations on roads...snowfall intensity up to 1"/hr and
snowfall totals of 1-3" across the east slopes of the Berks
westward. This is not out of the question given the evaporative
cooling potential with super dry airmass in place. It will come
down to if precip intensity via diabatic and dynamic cooling
processes can offset low level warming as winds turn ESE. 00z NAM
soundings show column becoming isothermal 18z-21z western MA as
precip intensity increases. Thus would not be surprised if a few
locations above 1000 ft elevation pickup a slushy 1-3". Hence
will continue with the Special Weather Statement to highlight this
snow potential. Earlier discussion below.


High pressure ridge moves offshore this morning. Strong
overrunning shifts E as low pressure shifts across NY state
today, with a warm front ahead. Mid and high clouds will continue
to thicken during the day. Enough lift and increasing low level
moisture as winds shift to E-NE during the day will cause
precipitation to push into the region. Dewpts will slowly rise
during the morning across central and western areas, so precip
should develop there.

Will see mixed rain/snow as precip starts especially across N
central and W Mass into N central CT. As the winds veer during
the day, precip will eventually change over to all rain except
across the higher terrain, generally the E slopes of the
Berkshires. Temps will remain chilly through the day, ranging
from the mid and upper 30s across the E slopes of the Berkshires
to around 50 along the immediate E coast.


Will see rapidly changing conditions as a secondary low develops
along the triple point of the frontal system as it pushes into the
region this evening. Strong low level jet develops as it wraps
around the low and approaches the region, on the order of 50 kt at
4-6Kft. 00Z short range models remain in very good agreement in
bringing this low across overnight, as well as rapidly increasing
SE winds mainly across E Mass into south coastal RI. Wind
advisories have been issued from E coastal and SE Mass into SE RI
and Block Island. The low will move steadily across the region, so
will see about 6-9 hour window of strong winds. Could see gusts up
to 45-55 mph, highest across E coastal Mass. Expect the strongest
winds between 05Z and 11Z, though could linger a bit longer across
the Cape Ann region. Winds will quickly shift to SW as the low
pushes E, but when the shift occurs still in question.

Excellent inflow of low level moisture along with the deepening of
the low across the region will bring periods of heavy rain onshore.
QPF amounts on order of 0.5 to 0.8 inches with some locally higher
amounts are forecast. May see some brief localized flooding in any
heavier rainfall, generally urban and poor drainage. Will also see
good elevated instability in place, so have also mentioned the low
risk for a band of scattered thunderstorms rotating across central
and eastern areas overnight.

With the overall E-SE wind flow in place through the night, temps
will bottom out early tonight before holding steady or slowly rising
after midnight.



* Temps more seasonable this period
* Risk of a few showers late Sat, a more widespread rain Sunday?
* Mainly dry and seasonable much of next week


At 12z triple pt low somewhere along northeast MA coastline and
continuing to deepen/strengthen as mid level low approaches from
NY state. Dry slot thru the region so drying trend develops with
just some leftover showers across northern-northeast MA early Fri
morning. However system becomes vertically stacked by afternoon as
mid level low captures surface reflection off the NH/ME coast.
This may result in comma head showers rotating back into northeast
MA and clipping the outer Cape Fri aftn. Elsewhere dry weather
should prevail along with increasing northwest winds as low
continues to deepen off NH/ME coast. Probably more clouds than
sunshine given cyclonic flow aloft persisting across the region.

High temps will likely be observed in the morning especially
across RI and eastern MA where leftover warm sector will yield
morning highs of 55-60. Low to mid 50s elsewhere with upper 40s
higher terrain.


Uncertainty as models continue to struggle with amplitude of lead
(Saturday) and trailing (Sunday) northern stream short wave
energy. As of now models bring low pressure across northern New
England Sat with attending cold front entering southern New
England late Sat and Sat night. This may be accompanied by a few
showers but much of the day and night will remain dry.

Then on Sunday both GFS and EC suggest trailing northern stream
short wave energy will be robust enough to spawn a weak frontal
wave on the front before boundary exits southern New England. This
would yield a risk of rain overspreading the region Sunday from
west to east. 00z GEFS ensembles have shifted in this direction as
well. Given time range and uncertainty will follow a model blend
and trend the forecast toward Sunday having the higher probability
of rain of the two weekend days.

Temps will be more seasonable than recent days with highs both
Sat and Sun 55-60. Although if frontal wave verifies Sunday could
be the cooler day given precip potential

Monday thru Wednesday...

Brief cool down Sunday night and Mon behind departing northern
stream short wave. However temps rebound nicely Tue and Wed as
subtropical ridge over the southeast states builds northward up the
Eastern Seaboard. Mainly dry this period with a low risk of showers
sometime around Wed as northern stream energy and attending cold
front move into New England and begin to erode the northern portion
of this subtropical ridge.


Forecaster Confidence Levels.

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

7 am update...

Not much change from previous TAFs. Light ocean effect rain/snow
showers impacting coastal Plymouth county this morning may expand
northward into Boston area later this morning with marginal
MVFR/VFR conditions. Snow overspreads western MA/CT 15z-18z and
may become moderate for a time 18z-21z. Elsewhere rain overspreads
the region this afternoon and becomes moderate to heavy late in
the day.


Short Term /through Tonight/...

Today...High confidence in trends, lower on timing. Area of light
snow and rain moves into central and western areas by mid morning.
Mixed precip should change to rain as winds shift to E-SE and
temperatures rise. Mixed -RA/-SN may lingers across the E slopes
of the Berkshires with MVFR CIGS/VSBYS mainly around or after 16Z-
18Z. Should not see snow accumulations on runways, but a light
coating is possible across the higher terrain of the Berkshires
(mainly AOA 1000-1500 feet). Should remain mainly VFR through
midday, then CIGS/VSBYS lower to MVFR to local IFR from W-E during
the afternoon. Should remain mainly VFR across E Mass until

Tonight...Moderate confidence in trends, lower for timing. Expect
mainly MVFR conditions with areas of IFR in rain and fog. May see
leftover mix of snow along the E slopes of the Berkshires early,
but temps will slowly rise overnight so should end. Rain will be
heavy at times, along with brief period of scattered thunderstorms
mainly across central and eastern areas around or after midnight.
E-SE winds increase across RI/E Mass, with gusts up to 30-40 kt
mainly around or after midnight. LLWS likely, especially between
05Z and 12Z when winds shift from SE to SW-W as low pressure moves

KBOS TAF...High confidence in trends, lower confidence in timing.

KBDL TAF...High confidence in trends, lower confidence in timing.

Outlook /Friday through Monday/...

Friday...Moderate confidence.

Areas of MVFR cigs/vsbys in showers early, but trending VFR during
the day.  Northwest winds increase with gust potential 30 to 40

Saturday-Sunday...Low confidence.

VFR likely Sat with perhaps a period of marginal MVFR in scattered
showers late Sat/Sat night.

Possible MVFR-IFR Sunday across CT/RI and southeast in periods of

Monday-Tuesday...Moderate to high confidence.

VFR and mainly dry weather.


Forecaster Confidence Levels.

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

Short Term /through Tonight/...High confidence.

Today...Winds shift to E-SE during the day as low pressure
approaches. Wind gusts may approach small craft criteria on the
waters S of Block Island by evening. Seas will remain below 5 ft.
Visibility restrictions move in during the afternoon in developing
light rain and patchy fog.

Tonight...SE winds will rapidly increase, gusting to gale force
by late this evening. Gale warnings have been issued. Seas will
build up to 6-8 ft by around midnight across the open waters, then
will push toward south facing near shore waters as they continue
to build overnight. Visibility restrictions in rain and patchy
fog. Low chance for thunderstorms.

Outlook /Friday through Monday/...

Friday...Moderate confidence.

Gale center near Cape Ann early Fri moves slowly into Gulf of ME Fri
afternoon. WNW gales all waters.

Saturday-Sunday...Low confidence.

Southwest winds 20-30 kt Sat ahead of approaching cold front.  Wind
shift Sunday morning to north behind departing front. However
boundary is slow to depart as low pres may form on the front over NJ
and then tracks south of Long Island Sun aftn and then across
Georges Bank Sunday night.

Monday-Tuesday...Moderate confidence.

Modest north winds Mon behind departing low pressure. Light winds
Tue as high pres crest over the area.


MA...Wind Advisory from 1 AM to 10 AM EDT Friday for MAZ007-014>024.
RI...Wind Advisory from 11 PM this evening to 5 AM EDT Friday for
MARINE...Gale Warning from 11 PM this evening to 11 AM EDT Friday for
     Gale Warning from 1 AM to 9 AM EDT Friday for ANZ230.
     Gale Warning from 10 PM this evening to 5 AM EDT Friday for
     Gale Warning from 9 PM this evening to 9 AM EDT Friday for
     Gale Warning from 1 AM to 6 PM EDT Friday for ANZ250-251.
     Gale Warning from 11 PM this evening to 6 PM EDT Friday for
     Gale Warning from 9 PM this evening to 2 PM EDT Friday for


LONG TERM...Nocera
MARINE...Nocera/EVT is the U.S. government's official web portal to all federal, state and local government web resources and services.