Blizzards occur in many parts of the world, including countries with a tropical climate. The conditions needed for a blizzard are cold air (below freezing), wind, and snowfall. This combination of factors causes a severe winter storm that is both hazardous and disruptive to travel and commerce. The wind and snowfall of a blizzard can also cause damage to power lines, making them hazardous to touch.
The blizzards that happen in the United States usually start in the Plains, an area of flat land covered with grassland and small hills. This terrain allows low pressure systems to build quickly, as they move southward over the Rocky Mountains and tap into cold Arctic air behind them. In addition, the lack of trees in this region means that wind and blowing snow can be more intense than in areas with more vegetation.
In order for a storm to be considered a blizzard, it must produce snow, have winds in excess of 35 miles per hour and last more than 24 hours. Blizzards can also have a whiteout condition, which is when the blowing snow makes everything look white. Whiteout conditions can be life-threatening, especially when people are driving and cannot see the road ahead.
A blizzard is the most serious type of winter storm. It can have life-threatening effects, especially when it combines snow and winds in excess of 35 miles per hour. In some cases, people are killed by falling objects or being stranded in vehicles. Blizzards can also shut down public transportation, such as buses and trains, and reduce visibility to less than a mile.