What conditions are necessary for a snow avalanche to occur?

• A. Wet snow, high winds, and temperature drops
• B. Favorable slope angle, heavy snowfall, changing temperatures, and a trigger
• C. Freezing rain and melting conditions
• D. Steep hills, heavy animal traffic, and warm weather

Answer: (B)

A snow avalanche occurs under specific conditions that significantly impact the stability of the snowpack. The necessary conditions include a favorable slope angle, which allows for gravitational forces to act on the snow layer; heavy snowfall, which increases the load on the existing snowpack; changing temperatures, which can cause fluctuations in the snow's cohesion and stability; and a trigger, such as a sudden event (like a snowstorm or human activity) that can cause the accumulated snow to release and slide downward.

These factors collaboratively influence the balance between the forces acting on the snowpack and the strength of the snow layers. When these conditions align, the risk of an avalanche increases dramatically, leading to potential hazards in mountainous areas. The other options do not encompass the essential components that make avalanches likely. For instance, while wet snow and high winds can contribute to certain conditions, they are not the primary or necessary factors for an avalanche to occur compared to the combination outlined in the chosen answer.