000
FXUS61 KBOX 130807
AFDBOX
Area Forecast Discussion
National Weather Service Taunton MA
407 AM EDT Tue Mar 13 2018
.SYNOPSIS...
Low pressure off the Carolina coast rapidly deepening into a
coastal storm, affecting southern New England tonight into
Tuesday night. This storm will deliver significant accumulating
snow, strong to damaging winds, coastal and marine impacts.
Blustery and chilly weather continues Thursday and Friday
followed by moderating temperatures this weekend. Dry weather
probably dominates late in the week through next weekend.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
* Highlights...
- Moderate to heavy snow, some locations seeing upwards of a foot
to perhaps two feet total accumulation
- 1-3"/hr snowfall rates at times, producing visibility less than
a quarter of a mile. Winds expected to yield blizzard
conditions to the east coastal shoreline of MA.
- Strong to damaging winds, E gusts up around 65 mph possible for
far E/SE MA coast, brunt of the winds around Tuesday morning
into early afternoon
- Impacting the Tuesday AM commute with difficult, near impossible
travel
- Especially the Tuesday morning high tide, strong E onshore flow
yielding around a 2 to 3+ foot surge, minor to moderate
coastal flooding issues, especially ocean-facing shores,
vulnerable areas impacted by earlier storm systems
*/ Discussion...
Precipitation intensity is a critical piece determining
precipitation type early this morning. Initial precipitation
type early this evening was light rain. As precipitation
intensity increased, seeing a rapid switch to snow across the
interior. Still some rain towards nantucket early this morning.
Overall, the ongoing forecast remains on track. Mainly minor
tweaks to snowfall forecast. The other change was to expand the
Blizzard Warning along the east coast of Massachusetts. It`s
possible, further expansion could occur later this morning. Just
don`t have enough confidence in the persistence requirement
away from the immediate coastline.
13/00Z guidance continues to converge towards a common track of
a low pressure offshore. There are still enough differences
where a consensus approach is preferred.
Seeing more signs in the guidance of two frontogenetical bands.
The primary band still appears to be across SE MA, with another
farther west across southern New England. Snow totals may need
to be adjusted if this western band lingers in place longer than
currently expected.
* Snow...
Looking at snowfall totals of 12-18 inches along the Worcester
Hills and far NE CT eastward, with some higher totals around
20 inches possible. Where the mesoscale banding sets up will
ultimately indicate where the highest snowfall totals will be.
Closer to the I-91 corridor from Greenfield to Hartford and
vicinity, thinking snowfall totals will range mainly from 8-12
inches.
Blizzard Warnings issued earlier today for coastal Essex County
MA, Plymouth County and the Cape and Martha`s Vineyard.
Elsewhere across southern New England Winter Storm Warnings
remain in effect for overnight thru Tuesday.
* Winds...
925-850 East winds 3-5+ standard deviation from normal, with 925 mb
winds 50-70 kts along far eastern SNE. Low level lapse rates indicate
sufficient mixing, when combined with precipitation drag, to generate
very gusty winds along the east coast of MA, particularly the Cape
and Islands. Continuing thinking that N/NE winds will gust up to
60-65 mph for the east coastal MA shoreline, with the exception
of the immediate Boston area. Blizzard Warning area includes the
area where these strongest wind gusts are expected, with the exception
of Nantucket. For Nantucket a switchover or mix with rain should
keep this area from hitting blizzard criteria. Hence a High Wind
Warning has been issued for Nantucket.
Again, the brunt of the winds will be this morning into early
this afternoon.
Have gone with snow/liquid ratios comparable to previous forecast,
which is a model blend. Expecting a mainly dry/fluffy snow for
much of the interior. Plymouth County and the Cape and islands
are at greatest risk for a heavy/wet snow plus strong winds,
yielding some potential tree damage and power issues.
&&