What makes a snowstorm a blizzard? How frequently does Chicago get a blizzard?
Thanks, George Kalinka, Naperville
The National Weather Service defines a blizzard as an intense winter storm with sustained winds or frequent gusts of 35 mph+ combined with considerable falling and/or blowing snow that frequently reduces the visibility to one-quarter mile or less for a minimum of three hours. While storms that produce blizzard conditions often deliver large amounts of snow, a ground blizzard can occur with clear skies if winds are strong enough and the visibility requirement is satisfied by blowing snow. Because buildings block and slow winds, blizzards are more common in rural areas. Chicago seldom experiences a true blizzard, usually just once or twice a decade, but brief periods of blizzard conditions will occur almost every winter.