When
the entire snowpack slowly moves as a unit on the ground, similar
to a glacier.
Glide avalanches:
Glide occurs when the entire snowpack slowly slides as a unit
on the ground, similar to a glacier. Don't mistake glide for
the catastrophic release of a slab avalanche that breaks to
the ground. Glide is a slow process, that usually occurs over
several days. Glide occurs because melt water lubricates the
ground and allows the overlying snowpack to slowly "glide"
downhill. Usually, they don't ever produce an avalanche but
occasionally they release catastrophically as a glide avalanche.
So the presence of glide cracks in the snow do not necessarily
mean danger. It's often difficult for a person to trigger a
glide avalanche but at the same time it's not smart to be mucking
around on top of them and especially not smart to camp under
them.
We tend to find them in wet climates and when they occur in
dry climates they do so in spring when water percolated through
the snow or sometimes during mid winter thaws.
When do they come down? Like an icefall, they come down randomly
in time--when they're good and ready--not before. You would
think that they would come down during the heat of the day or
when melt water running along the ground reaches its maximum.
But oddly enough, they tend to release just as often with the
arrival of cold temperatures following melting as during melting
itself. It's hard to play a trend with glide avalanches. They
come down when they're good and ready and it's impossible to
tell when that is. Just don't spend much time underneath them.
