National Weather Service United States Department of Commerce
 

An avalanche is a rapid flow of snow down a hill or mountainside. Although avalanches can occur on any steep slope given the right conditions, certain times of the year and types of locations are naturally more dangerous. While avalanches are sudden, there are typically a number of warning signs you can look for or feel before one occurs. In 90 percent of avalanche incidents, the snow slides are triggered by the victim or someone in the victim's party. Avalanches kill more than 150 people worldwide each year. The National Weather Service provides current weather conditions and forecast information to regional avalanche forecast centers that in-turn issue avalanche forecasts. Avalanche warnings and special advisories are included on NWS websites and broadcast over NOAA Weather Radio. Refer to your local avalanche center for current snowpack conditions!

+How to Stay Safe

+Avalanche Warning Signs

The following are a few of the warning signs of unstable snow and possible avalanches:
  • You see an avalanche happen or see evidence of previous slides.
  • Cracks form in the snow around your feet or skis.
  • The ground feels hollow underfoot.
  • You hear a "whumping" sound as you walk, which indicates that the snow is settling and a slab might release.
  • Heavy snowfall or rain in the past 24 hours
  • Significant warming or rapidly increasing temperatures
  • You see surface patterns on the snow made by the force of strong winds. This could indicate that snow has been transported and deposited in dangerous drifts that could release.

    For more on avalanche warning signs and additional information, take our avalanche tutorial.

+Avalanche Resources