The statement is - True.
The avalanches are a very dangerous occurrence. They are very heavy, carry a lot of snow, and are also very fast, so for anyone on their way it is likely to end up very tragically.
The avalanches are essentially a downhill fast moving snow. They usually appear after 24 hours of when a heavy snow of over 12 inches fell. They mostly appear on very steep slopes. Because the large amount of snow brings in a lot of weight and pressure, and the steepness of the terrain can not support all that weight and pressure in one place, the snow starts to move. The movement is sudden, with the snow managing to accelerate to 80 mph/h in just 5 seconds.