Remote triggering usually involves thick layers of the persistent forms, or widespread weaknesses in storm snow such as heavier layers over lighter layers. When the weak layer collapses, the downward motion of the snow above the weak layer provides energy to drive fracture propagation. Imagine if you stepped on the top of the arch and the lowest blocks were suddently crushed by the extra weight? What would happen to the upper blocks?

The weak layer collapse, along with the subsequent propagation of the disturbance, causes a type of material failure referred to as delamination. The collapse breaks the intercrystalline bonds between the slab and the weak layer, leaving the upper slab “bonded” to the slope by static friction alone. If the slope is steep enough, gravity is able to overcome static friction and pull the slab, which results in the slab being torn away from its margins. The slab breaks apart as it moves downhill.

Read this paper:

http://www.issw2008.com/papers/P__8212.pdf

You’re probably familiar with firn quakes. The model of avalanche formation you attempt to describe is basically the same as a firn quake.

Firn Quakes

http://traverse.npolar.no/expedition-diary/archive/2007/12/21/firn-quake