The snowpack often displays visible, palpable and audible signs of unstable snow. These are warnings that indicate potentially dangerous conditions exist:
- Whumpfing (the sound of snow collapsing) and cracking, especially shooting cracks. This suggests thick weak layers and cohesive slabs are primed for avalanches, given a sufficiently steep and open slope.
- Recent avalanche activity suggests that slopes with similar characteristics in terms of elevation, aspect, incline, shape, etc. that have yet to produce avalanches are likely to be unstable.
- Hollow sounds or sensations, like you’re walking on a drum. This suggests thin hard slabs with very little underlying support, and can indicate a thin snowpack area, where triggering is more likely, on an otherwise well covered slope that can produce a large avalanche. Take a look around, and if there are exposed rocks or trees scattered about, then you are likely in a thin snowpack area.
- Difficult travel because you’re breaking trough heavy surface snow into underling light snow, which can also be felt by probing with a ski pole, ice axe, etc. This is also known as “up-side down snow”, because light snow on top is the right side up for good riding, and can indicate wind slabs or storm slabs that are primed for avalanches.