Here we see some skiers entering an area that is normally pisted and patrolled, but is not now due to COVID closures.
Why does it release? It is a potent combination that makes it so unstable.
A weak layer due to a long period of November dry cold weather and clear skies that led to the creation of a weak layer of ‘facets’ (snow grains that looks and feels a bit like rock salt – with no cohesion) on mainly on North facing slopes, but on many other slopes as well – not so much on slopes facing South’ish; we often say that these dry weather conditions rotted the old snow. The new snow sits on top of this. There is no skier compaction, so it is virgin new snow which is less stable. There is no ski patrol to blast the slopes.
Now going onto slopes that you are familiar with, when usually nothing happens due to skier compaction and piste security blasting, can be deceiving. The familiarity leads to complacency as you might head down something without doing a proper assessment.
There is no avalanche danger rating in the resort to alert you to the level of risk, but Météo France has started doing bulletins and ratings click on this link (then choose “RISQUES-AVALANCHE) https://meteofrance.com/meteo-montagne/alpes-du-nord/enneigement
As far as we can see on the video the skiers headed off down a slope that is usually a piste. This could have given them a false sense of security.
They were lucky. Fortunately, they were good skiers and got out fast. But they did not help the situation by all setting off at the same time. It is not clear whether one skier or several skiers triggered the release. But the avalanche did then trigger other avalanches in the bowl ‘remotely’, especially to the skiers right of the lift.
In any case this is another ‘sign of things to come’!
See these recent posts to see how this event is a logical progression in the evolution of weather, snowpack and ‘human interaction’
Have fun, stay safe.