It's that time of year — again — when cold air sweeps across the Great Lakes region, dropping huge amounts of lake-effect snow into Western New York.

WWNY reports the Sheriff’s Office of Lewis County, New York has issued a travel advisory for all of Lewis County.

According to the county Sheriff, the travel advisory will remain in place until further notice, and was issued for poor road conditions and blowing snow.

When cold air, often from Canada, blows over the Great Lakes it can spell weather trouble for Michigan, Ohio, New York and other states in the region.

Warming air from the lakes pushes the moisture in the sky higher into a zone most conducive to snowfall because of its temperature. Clouds capable of dumping heavy precipitation downwind then form.

Most of the moisture needed for lake-effect snow does not actually come from the lakes, but rather from cold air that blows over them.

Add a fairly stationary wind direction and the right conditions can be created for heavy snowfall.

AP video shot by: Cara Anna