CHICAGO (CBS) — When does a snowstorm become a blizzard?
Actually, it has nothing to do with the amount of snow that falls. It has to do with the wind.
A blizzard is characterized as a snowstorm with strong winds and poor visibility. To qualify as a blizzard, there must be snow, of course–but winds have to blow in excess of 35 mph for three hours or more. Also, visibility must be below a quarter mile.
Right now, the forecast for Tuesday’s storm has the makings of a true blizzard–with strong winds and lots of snow. The worst blizzard to hit Chicago happened in January, 1967 when nearly two feet of snow fell and winds howled up to 50 mph and created drifts as high as 10 feet.
Tuesday’s storm could dump anywhere from 12-22 inches of snow with winds at 20-35 mph or more. The storm is expected to hit hard on Tuesday afternoon. The heaviest snow is expected to fall early Wednesday morning, between 2 a.m. and 5 a.m.