Widespread synoptic snow will be ongoing Tuesday morning as a weak
low tracks towards the Delmarva. As the low slides to our south, we
will remain well within the cold side of the system. Additional snow
amounts into Tuesday afternoon remain close to continuity and latest
WPC guidance with 2-3" focused south of the Thruway and 1-2" to
the north including the Buffalo, Rochester and Watertown areas.
The low will deepen a bit as it moves approaches the New Jersey
coast late Tuesday. This will pull the deeper moisture away
from the area with the synoptic snow diminishing from west to
east through the afternoon.
Lake enhanced snow starts not too far behind the ending of the
synoptic snow, as colder air starts to work into the area behind
the departing low. The initial lake response will be muted, but
will take on an uptick as we move through Tuesday night and
into early Wednesday as moisture increases from an upstream
shortwave trough and an approaching cold front. This sharp cold
front will sweep through the region Wednesday morning bringing
an arctic blast into the region. Strong cold air advection
behind the front will send 850 mb temperatures plummeting to
between -20C and -22C by Wednesday afternoon, producing extreme
over-lake instability. A period of at least moderate intensity
lake effect snow will develop during this time period.
There may be a period late Tuesday night into Wednesday morning that
the lake snows could focus northeast of the lakes ahead of the cold
front, possibly as far north as the Buffalo metro area, but the
west-northwest flow behind the front will quickly shift the
lake snows southward into the Boston Hills, higher terrain of
Wyoming county and the Chautauqua ridge for much of the day
Wednesday. The lake effect snow should continue straight into
Wednesday night before slowly diminishing in intensity as we get
to Thursday morning, with the approach of surface high pressure
from the Ohio Valley and associated dry air and subsidence
causing inversion heights to come down. Accumulations at the
stage look to be at least several inches and certainly plowable
for areas east of the lakes.