Where Do They Occur?
About 90% of
all the avalanches begin on slopes between 30 to 45 degrees;
about 98% of all the avalanches occur on slopes between 25 to 50
degrees. Avalanches start most often on slopes above the
timberline that face away from prevailing winds. Avalanches can
run, however, on small slopes well below the timberline, such as
gullies, road cuts, and small openings in the trees. Very dense
trees can anchor the snow to steep slopes and prevent avalanches
from starting; however avalanches can release and travel through
a moderately dense forest. Most avalanches occur in the
backcountry, outside of developed ski areas.