The most perilous of winter storms combining falling, blowing, drifting snow, winds of 40 km/hour or more, visibility less than 1 km, temperatures less than -10_C; duration: six hours or more.
Ten centimeters or more in 12 hours, or 15 cm or more in 24 hours. Even less in temperate climates..
Freezing rain or drizzle
An ice storm coating roads, trees, overhead wires, etc. with ice.
A rapid fall in temperature in a short period, requiring greater than normal protective measures.
The cause of blizzard conditions, drifting, reduced visibility and wind-chill effects.
Where the road ahead looks like black and shiny asphalt. Shaded areas of the road, bridges and overpasses freeze sooner in cold weather, long after the sun has come out.
Reference:The above information are aparts of complete publications. This publications are available online from the following links (Click on the blue text)
Goverment of Canada Winter Driving
Ministry of Transportation of Ontario Winter Driving