Avalanche Forecast

Archived

Dec 13th, 2011–Dec 14th, 2011

Alpine

Natural avalanches unlikely.

Treeline

Natural avalanches unlikely.

Below Treeline

Natural avalanches unlikely.

Alpine

Natural avalanches unlikely, human triggered possible.

Treeline

Natural avalanches unlikely.

Below Treeline

Natural avalanches unlikely.

Alpine

Natural avalanches unlikely, human triggered possible.

Treeline

Natural avalanches unlikely.

Below Treeline

Natural avalanches unlikely.

Regions

Sea To Sky.

Confidence

Good - -1

Weather Forecast

Wednesday: Cloudy with flurries turning to light snowfall with associated moderate southwesterly winds in the afternoon. Freezing levels are expected to drop throughout the day to valley bottoms. Thursday: Snow tapering off throughout the day with a storm total of 10-20cm expected by the afternoon. Continued moderate southwesterly winds and 900m freezing levels. Friday: A mix of sun and cloud, light winds, and freezing levels in valley bottoms.

Avalanche Summary

There have been no recent avalanches reported. Although the likelihood of triggering deep persistent slab avalanches is now low, the potential consequences are still very high.

Snowpack Summary

The snow surface is wind hammered in exposed areas, a strong melt-freeze crust on solar aspects, and dry faceted powder with large surface hoar on shady sheltered slopes. A thick crust is down 20-40cm at treeline and below. Deep persistent weakness appear to be dormant, but we can't rule out triggering from shallow areas just yet. Recent snowpack tests in the Whistler area produced sudden results on an old and isolated midpack surface hoar weakness. Check out the Forecaster's Blog link below for more snowpack discussion and good advice.

Problems

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.