The combination of strong high pressure ridging across northwest
Ontario seeping down into the eastern Great Lakes and the approach
of the low will allow for near-surface winds to turn east and
northeasterly, allowing for low-level cold air to be reinforced from
the north. However, the track of the surface low will be an
important factor to the low-level thermal profile across the area,
especially in the vicinity of the New York State Thruway as this
region looks to be the delineation line between rain/wintry mix to
the south and mainly snow to the north.
Confidence at this point is relatively high that the cold air will
hold north of the Thruway, even through the daylight hours Saturday.
This will result in a mainly snow event. For areas south of the
Thruway there is a warm nose in the 5-10 kft layer where a wintry
mix is initially likely before a transition to rain. The wintry mix
is not excepted to be of long duration which should limit any icing
to fairly light amounts of less than a tenth of an inch.
Snow accumulation potential will be greatest where the cold air can
hold on the longest. Best potential for roadways and paved surfaces
to see accumulations will be north of the Thruway, and depending on
rates, could see totals in the 3-6 inch range, with the higher end
of this range most likely over the higher terrain of the Tug Hill
east of Lake Ontario with amounts closer to 3 inches west of
Rochester, including Batavia and Buffalo. Thinking on these
preliminary amounts could easily change depending on the low track
which will be a big determining factor with the thermal profile.