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Gliding avalanches

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What?

Characteristics

The entire snowpack is gliding on the ground, typically on smooth ground such as grassy slopes or smooth rock zones. High activity of glide-snow avalanches are typically related to a thick snowpack with no or only few weak layers. Glide-snow avalanches can occur both with a cold dry snowpack and with a warm moist or wet snowpack. The release of a glide-snow avalanche is difficult to predict, although in many cases glide cracks open prior to release.

Expected avalanche types

  • Glide-snow avalanches; cold dry or 0 °C isothermal wet snowpack
  • Almost exclusively natural avalanches. Human and artificial triggering is very unlikely.

Where?

Spatial distribution

Primarily on smooth ground and on slopes of any aspect, but more often on south-facing slopes.

Position of the weak layer in the snowpack

Interface between the ground and overlaying snowpack

Why?

Release characteristics

Glide-snow avalanches are caused by a loss of friction in a moist to wet layer at the snow-ground interface.

When?

Duration

Days to months; occasionally during entire winter-season. The release can occur at any time during the day. In spring, glide-snow avalanches occur mostly during the second part of the day.

How to manage?

Identification of the problem in the field

With the presence of glide cracks the problem can often be localized; however, the presence of glide cracks does not indicate imminent avalanche release, which is nearly impossible to predict. Avalanche release without pre-existing glide cracks is also common.

Travel advice

Avoid areas close to glide cracks.

Typical accident

Stanserhorn, Stans (NW), 24 February 2012