The best chance for accumulating snow is Sunday and Sunday night.
However, surface temperatures will marginal for snow and so snow
will struggle to accumulate. Model QPF has also been a challenge,
with some models and runs significantly higher than others. In
general, upsloping will play a significant role, along with deep
moisture associated with the upper low, and a secondary trough which
is forecast to move through Sunday night. Southwesterly winds
typically do not upslope effectively, and suspect some model
guidance has overdone lake enhancement which should be minimal. Base
don this, have hedged toward model runs with lower QPF amounts. A
more WSW surface flow will support better upsloping Sunday night,
and this may be when the most snow accumulates.
Snowfall amounts will vary by location, with generally the greatest
amounts across higher terrain east of the lakes where there will be
some orographic enhancement and where it will be the coldest. Snow
amounts are likely to fall in the advisory range with 24-hour storm
totals in the 4 to 8 inch range at these locations. The Tug Hill
bears some watching, with slightly higher amounts possible, but held
off on watch headlines considering that snow will likely be wet and
have poor liquid equivalent ratios. Elsewhere there will be minimal
accumulation. This includes the Buffalo and Rochester metro areas, I-
90 along Lake Erie, the Genesee River Valley, and western Finger
Lakes. Expect only a slushy inch or two at these locations