Most avalanches happen during or right after a snowstorm. However, any time new snow falls and the wind moves it through the terrain, avalanches are possible. New snow often has a hard time adhering to hard, icy old snow surfaces, so a fall snowstorm can produce small avalanches if it falls onto old snow, grassy areas or rock slabs. The best way to manage these avalanches in the fall is to have a current weather forecast, recognize when there is enough snow to produce avalanches, and select terrain that minimizes your exposure to the risk.

New Snow Avalanches can release as either a soft cohesive layer (slab), or as loose, dry sluffs that start at a point and fan out as they entrain more snow. Loose, dry avalanches are generally harmless but they could carry you over rocks or cliffs if enough snow is involved. Soft slabs in the new snow are more dangerous. They often form when new snow falls with light winds or in wind-sheltered areas. Instability typically last for a few days. You can reduce your risk from Storm Slabs by waiting a day or two after a storm before venturing into steep terrain. Storm slabs are most dangerous on slopes with terrain traps like gullies or cliffs, or slopes that end in timber or scree fields.

Wind Drifted Snow avalanches are caused by slabs that form when wind transports snow from the windward sides of terrain features and deposits it on the leeward side. Wind drifted snow often appears smooth and rounded, and sometimes sounds hollow. Wind drifts form in specific areas leeward of terrain features. You can reduce your risk from wind slab avalanches by sticking to wind-sheltered or wind-scoured areas and avoiding drifted slopes.