From the NWS (emphasis mine):

&&

.SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
* POTENTIAL HISTORIC WINTER STORM AND BLIZZARD TO IMPACT MUCH OF
  SOUTHERN NEW ENGLAND FRI INTO SAT

* 1 TO 2 FEET OF SNOW POSSIBLE FOR MUCH OF SOUTHERN NEW ENGLAND
  EXCEPT AREAS NEAR THE SOUTH COAST WHERE THERE MAY BE SOME MIXING

THE MODELS HAVE COME INTO VERY GOOD AGREEMENT ON A POTENTIALLY
HISTORIC WINTER STORM AND A POSSIBLE BLIZZARD THAT WILL IMPACT MUCH
OF SOUTHERN NEW ENGLAND.  WE ARE CONFIDENT THAT MUCH OF THE REGION
WILL RECEIVE 1 TO 2 FEET OF SNOW.  STILL TOUGH TO PINPOINT WHERE THE
BEST CHANCE FOR THE HIGHER AMOUNTS WILL BE...BUT CLIMATOLOGY FAVORS
THE I-95 CORRIDOR.  WE ALSO EXPECT A MID LEVEL DEFORMATION BAND THAT
WILL LEAD TO LOCALIZED HIGHER AMOUNTS ACROSS THE INTERIOR.  THE BULK
OF THE STORM APPEARS TO BE IN THE FRIDAY NIGHT/SATURDAY MORNING TIME
FRAME.

THE HIGHEST LEVEL OF UNCERTAINTY IS ASSOCIATED WITH THE AMOUNT OF
WARM AIR THAT COMES IN AT MID LEVELS FRIDAY AFTERNOON AND EVENING.
THE NAM BRINGS THE WARM AIR THE FARTHEST NORTH UP TO AROUND
PROVIDENCE AND TAUNTON. THE GFS...ECMWF...AND SREF ARE ALL A BIT
MORE CONSERVATIVE KEEPING IT MORE CONFINED TO THE SOUTH COAST.
THIS WOULD RESULT IN A CHANGEOVER TO RAIN OR A MIX OF RAIN...
SNOW...OR SLEET...UNDERCUTTING THE SNOW TOTALS IN THESE AREAS.

SPECIFIC DETAILS...

LIGHT SNOW STILL EXPECTED TO DEVELOP ACROSS SOUTHERN NEW ENGLAND
FRIDAY MORNING AS LOW PRESSURE MOVES OUT OF THE GREAT LAKES AND IS
ABSORBED BY A STRONGER LOW TO THE SOUTH.

[some details deleted]

AS MENTIONED ABOVE...THE BIGGEST
UNCERTAINTY IS HOW FAR THE RAIN/SNOW LINE TEMPORARILY ADVANCES
NORTHWARD.

WE ARE PRETTY SURE THE CAPE/ISLANDS WILL AT LEAST SEE A MIX OF
SNOW AND RAIN...AND PERHAPS FOR A BRIEF PERIOD NEAR THE SOUTH
COAST. IF THE NAM IS CORRECT ITS POSSIBLE THAT THE RAIN/SNOW LINE
MAKES IT INTO RHODE ISLAND AND SOUTHEAST MA.

THE MAIN SHOW LOOKS TO BE FRIDAY NIGHT INTO SATURDAY MORNING AS
THIS LOW BOMBS OUT AND TRACKS NEAR THE BENCHMARK. MID LEVEL
CENTERS RAPIDLY CLOSE OFF WHICH WILL LEAD TO TREMENDOUS SNOWFALL
RATES AND PERHAPS EVEN SOME THUNDER ACCOMPANYING THE STORM. WOULD
EXPECT HOURLY SNOWFALL RATES ON THE ORDER OF 2 TO 3 INCHES PER
HOUR WITH A TREMENDOUS COLD CONVEYER BELT ON THE BACKSIDE OF THIS
SYSTEM.

IN ADDITION...VERY STRONG WINDS OF 50 TO 60 MPH WILL BE BATTERING
THE COASTAL PLAIN LEADING TO CONSIDERABLE BLOWING AND DRIFTING
SNOW. WE MENTIONED THAT CLIMATOLOGY WOULD FAVOR THE I-95 CORRIDOR
AND AREAS A BIT NORTHWEST OF THAT REGION TO RECEIVE THE HIGHEST
SNOW TOTALS. HOWEVER...THERE WILL BE A MID LEVEL DEFORMATION ZONE
THAT SETS UP ACROSS THE INTERIOR ON THE BACK BENT MID LEVEL WARM
FRONT. WHERE EXACTLY THAT SETS UP WILL COME DOWN TO THE MESOSCALE
ENVIRONMENT SO ITS IMPOSSIBLE TO PINPOINT AT THIS TIME. THAT IS
WHY WE ARE LOOKING AT 1 TO 2 FEET OF SNOW ACROSS A GOOD CHUNK OF
THE REGION...EXCEPT NEAR THE SOUTH COAST.

TRAVEL MAY BECOME ALMOST IMPOSSIBLE WITH BLIZZARD CONDITIONS
POSSIBLE. A BLIZZARD WATCH HAS BEEN EXPANDED TO COVER SOUTHERN
WORCESTER COUNTY AS WELL AS ALL OF EASTERN MA...SOUTHERN RHODE
ISLAND AND NORTHERN CONNECTICUT. THIS BLIZZARD WATCH INCLUDES THE
BOSTON TO PROVIDENCE CORRIDOR...GIVEN THE POTENTIAL FOR 50 TO 60
MPH WINDS AND CONSIDERABLE BLOWING AND DRIFTING SNOW. THE TIMING
OF THE BLIZZARD CONDITIONS WILL NOT EXACTLY MATCH THAT OF THE
WATCH AS IT STANDS NOW. THIS TIMING WILL BE REFINED WITH LATER
FORECASTS. THE HIGH WIND WATCHES HAVE BEEN DROPPED IN FAVOR OF THE
BLIZZARD WATCHES.

FARTHER SOUTH ALONG THE SOUTH COAST INTO COASTAL PLYMOUTH COUNTY
AND THE CAPE...THERE MAY BE A PERIOD OF SNOW MIXED WITH RAIN OR
EVEN A COMPLETE CHANGEOVER TO RAIN FRIDAY AFTERNOON INTO EARLY
EVENING. IF THAT DOES HAPPEN...THINGS WILL QUICKLY CHANGE TO SNOW
AS LOW PRESSURE EXPLODES OFF THE COAST AND HEIGHTS CRASH.

ACROSS THE ISLANDS...SNOW WILL PROBABLY DEVELOP AND QUICKLY CHANGE
TO RAIN FRIDAY AFTERNOON.  RAIN MAY CONTINUE AT TIMES INTO FRIDAY
EVENING...BEFORE THE LOW BOMBS OUT AND THAT REGION FLIPS TO HEAVY
WET SNOW.  ACCUMULATIONS ARE MORE UNCERTAIN IN THIS REGION GIVEN THE
TIMING OF THE CHANGE OVER...BUT THE POTENTIAL FOR 6+ INCHES AND
PERHAPS EVEN A PERIOD OF BLIZZARD CONDITIONS INTO SATURDAY WILL BE
POSSIBLE.  THE BIG CONCERN IN THAT REGION WILL BE THE POTENTIAL FOR
HURRICANE FORCE WIND GUSTS THAT COULD RESULT IN SOME STRUCTURAL
DAMAGE.

&&

No, they’re not hedging their bets on this one.