A blizzard is when we experience moderate or heavy falling snow with winds speeds of 30 mph or more and visibility of 200 metres or less.
The phrase originated in North America, the term originally referring to a blast of gunfire. In the UK, in common usage the word often refers to any remarkably heavy fall of snow.
How is a blizzard defined?
At the Met Office we define a blizzard as moderate or heavy falling snow (either continuous or in the form of frequent showers) with winds speeds of 30 mph or more and a reasonably extensive snow cover reducing visibility to 200 metres or less.
How do blizzards occur?
Blizzards can occur either when snow is falling in windy conditions or when it is lifted from the ground by strong winds (known as a 'ground blizzard') or a combination of both facts.
A 'whiteout' is an extreme form of blizzard in which downdrafts and heavy snowfall combine to create a situation in which it is impossible to tell the ground from the sky.