Who defines how much snow a storm must produce to be a blizzard?

Dear Tom,
A winter storm must produce at least 6 inches of snow to be called a blizzard. Who sets that definition?
— Mel Festelli
Dear Mel,
That definition of a blizzard is incorrect. A blizzard does not have to produce snow. The National Weather Service defines a blizzard as a storm that produces sustained winds of 35 mph or higher with enough snow in the air, falling and/or blowing and drifting, to reduce visibility to less than one-quarter mile for at least three consecutive hours.
Blizzards have occurred in open areas like the Great Plains under clear skies, but with enough loose snow on the ground to cause whiteout conditions when blown into the air by relentless strong winds. Also, there is no specific temperature criterion. However, even if temperatures are hovering near freezing, strong winds will drop wind-chill readings to the teens or lower.
A blizzard does not have to produce snow, and there is no specific temperature criterion.

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