Prime feature: Marginal Early Season Event.
After a quiet and mild fall, the 2012-13 lake effect snow season got
underway a few days past Thanksgiving. A broad low amplitude trough was
carved across North America with -10c 850 hPa air pouring over the Eastern
Great Lakes. The lake temperatures averaged near normal (8c), in part to a
rare, below normal temperature, month of November. Modest lake instability
existed, and moisture ahead of a mid level shortwave re-energized lake bands
Sunday morning off both Lake Erie and Lake Ontario. Westerly winds brought a
narrow band of lake effect snow just to the south of the city of Buffalo Sunday
morning and early afternoon, while over the longer fetch of Lake Ontario backing
westerly winds drove over a foot of snow across the Tug Hill Plateau.
Very early Sunday morning the flow across the Eastern Great Lakes was west-northwest
which brought accumulating snow across Ski Country off Lake Erie, and the Wayne to
Oswego county corridor off Lake Ontario. Several upper level short waves rolled past
the region, one Sunday afternoon and evening and another during the day Monday. Ahead of
the first short wave winds backed to southwesterly which brought a band of snow towards
Buffalo early Sunday afternoon, and towards Watertown off Lake Ontario later in the day.
By Sunday evening drier air swept across Lake Erie which brought an end to the lake
effect snow. Snowfall totals ranged up to 7 inches off Lake Erie just south of Buffalo
where a persistent narrow band (3-5 miles wide) of snow fell through the early afternoon hours.
On the east end of Lake Ontario a greater depth of moisture remained Sunday evening which fed
into the lake effect snow band. Snowfall rates of 1 to 2 inches per hour accompanied this band of
snow, with the band meandering northward towards Watertown late Sunday evening. Behind the first
shortwave winds quickly veered to the west and northwest which dropped the lake effect band of snow
quickly towards Wayne, Cayuga and Oswego Counties. An upstream connection to Georgian Bay, combined
with a convergent flow over Lake Ontario maintained the lake effect snow band southeast of Lake Ontario,
and towards Lewis county through the night.
Monday ahead of the second, weaker shortwave this band of snow off Lake Ontario lifted northward through
the morning hours. Snowfall rates decreased to an inch per hour, and the band of snow became broader as
wind shear increased. This band of snow continued into the afternoon hours, though in a weakened state.
This was a modest event on a Sunday into Monday. Route 81 through Oswego county waas closed temporarily
Sunday disrupting holiday traffic heading home. It therefore earns 2 ** stars.
Here are some representative reports.
Off of Lake Erie...