The heaviest snow is now covering far WNY this evening with
snow rates of 1-1.5"/hr, with lower snow rates further east. The
SE edge of the precipitation band has been somewhat stubborn
over the past several hours, with a few areas in the Southern
Tier seeing very little or no precipitation thus far, although
that will change overnight with a burst of snow. Areas along the
SE edge have also had a little mixed precipitation, either from
a warm nose poking across the 0C line near the state line, or
from a lack of moisture in the column further NE across the
Finger Lakes to the Southern Adirondacks. But all areas should
see snow, or a return to snow as the upstream trough continues
eastward and finally pushes the slow moving band of
precipitation east overnight.
Once the steady snow moves east, expect a notable decrease in
snow intensity from west to east late tonight through early
morning Tuesday. Initially, the airmass will not cold enough in
the boundary layer to support lake enhancement with the
favorable dendritic crystal growth zone residing way up at
around 15K feet. This will change later tonight during the last
few hours of this event as the favorable dendritic crystal
growth zone descends beneath the lake induced equilibrium level.
This will bring some added snowfall along the south shore of
Lake Ontario from Niagara County eastward to Wayne County,
including the Rochester area.
A Winter Storm Warning remains with storm total accumulations of 7-
10 inches, with some local amounts of close to 12 inches where
mesoscale banding and/or lake enhancement develops. The bulk of this
accumulation will be through the pre-dawn hours of Tuesday,
when travel conditions will be worst. Snowfall amounts will be
much lower across far southern Cattaraugus and southern Allegany
counties, where the wintry mix will hold snow amounts to the
3-5 inch range