Whumpfing and cracking continue to occur. Avoid big slopes or terrain with high consequences. Watch those steep roof lines Santa!
Weather Forecast
Christmas Day will bring a mix of sun and cloud, light SW winds, temperatures between -15 and -20 and no new snow. For Boxing Day expect much of the same but about 5 to 10 degrees warmer.
Avalanche Summary
A couple of new naturally triggered slab avalanches were observed today in steep Alpine terrain. Overall the natural activity has tapered, but there has been recent activity up to size 3.0 primarily on East and North aspects over the past few days. Wide propagations have been observed and some slides have reached the valley bottoms.
Snowpack Summary
Wind slabs are widespread in the Alpine and at Treeline, with slabs up to 120cm thick. The Dec 10th surface hoar/facet interface remains active, with easy to moderate shears down 40 to 60cm. The basal layers are very weak and facetted, with occasional ski penetration to ground when you leave the up-track. Forecasters experienced a very large settlement today which indicates the snowpack remains prime for human-triggering.
Problems
Persistent Slabs
Persistent Slab avalanches are the release of a cohesive layer of snow (a slab) in the middle to upper snowpack, when the bond to an underlying persistent weak layer breaks. Persistent layers include: surface hoar, depth hoar, near-surface facets, or faceted snow. Persistent weak layers can continue to produce avalanches for days, weeks or even months, making them especially dangerous and tricky. As additional snow and wind events build a thicker slab on top of the persistent weak layer, this avalanche problem may develop into a Deep Persistent Slab.
Deep Persistent Slabs
Deep Persistent Slab avalanches are the release of a thick cohesive layer of hard snow (a slab), when the bond breaks between the slab and an underlying persistent weak layer deep in the snowpack. The most common persistent weak layers involved in deep, persistent slabs are depth hoar or facets surrounding a deeply buried crust. Deep Persistent Slabs are typically hard to trigger, are very destructive and dangerous due to the large mass of snow involved, and can persist for months once developed. They are often triggered from areas where the snow is shallow and weak, and are particularly difficult to forecast for and manage.