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Combine a steep mountain slope, some snow cover, and a weak layer in that snow cover. Add a trigger—more snow, a person, an animal—and you’ve got the recipe for an avalanche.

These masses of snow may roar down a mountain slope at speeds of up to 100 miles an hour. Even a small avalanche can reach speeds of 30 miles an hour.

Avalanches usually occur on 25 to 50 degree slopes during or just after large snowstorms. January through April is peak avalanche season in Colorado.

Avalanches rank as one of the deadliest forces of nature in Colorado. An average of six people die each winter in Colorado due to avalanches. Most of the fatalities involve snowmobile, backcountry and out-of-bounds skiers, and snowboarders.

Snow in an avalanche can be the density and consistency of wet cement. You don’t want to get stuck in it! Avalanches can be averted by avoiding conditions that favor avalanches; check out our featured links below for information on avalanche safety.

Featured Links:

Colorado Avalanche Information Center
This Web site includes avalanche warnings and reports, avalanche facts, a list of recent avalanche accidents, photos of avalanches, and information on avalanche safety courses. Before you head to the mountains, check the CAIC Web site for the latest conditions and warnings.

Avalanche!
This Web site from the PBS program NOVA explores the science of avalanches. Watch video clips of an avalanche and learn about avalanche safety.

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Photo credits: © Corbis Images, © NCAR, © NOAA, courtesy NEWS4, Colorado's news channel.