Avalanche Forecast

Archived

Dec 13th, 2013–Dec 14th, 2013

Alpine

Natural avalanches possible, human triggered probable.

Treeline

Natural avalanches unlikely, human triggered possible.

Below Treeline

Natural avalanches unlikely.

Alpine

Natural avalanches possible, human triggered probable.

Treeline

Natural avalanches unlikely, human triggered possible.

Below Treeline

Natural avalanches unlikely.

Alpine

Natural avalanches unlikely, human triggered possible.

Treeline

Natural avalanches unlikely, human triggered possible.

Below Treeline

Natural avalanches unlikely.

Regions

South Coast.

Confidence

Fair - Due to the number of field observations

Weather Forecast

A warm front will push across onto the south coast late Saturday. Freezing levels will rise before the the trailing cold front crosses the province on Sunday. Monday with be a pretty benign weather day ahead of the next low pressure system expected early in the week.Tonight and Saturday: Expect snow to start falling Saturday morning. This will turn to rain at lower elevations as the freezing level rises through the day from 600m to 1200m. Snow accumulations at higher elevations will range between 10 and 15cm in the Cascades, Pemberton Icecap and the Hurley with only a dusting forecast for the Duffy. Southwesterly ridgetop winds will start as moderate but become strong later in the day.Sunday: Light precipitation will continue before tapering off overnight. Ridge top winds will slowly diminish later in the day. Freezing levels will drop slightly in the wake of the cold front.Monday: A brief break ahead of the next system is forecast with overcast skies, light southwest winds and freezing levels holding at 1000m.

Avalanche Summary

No recent avalanche have been reported

Snowpack Summary

Snowpack depths vary greatly across the region with 160cm at treeline in the Cascades but only 50cm along the Duffy. Terrain below treeline is still mostly below threshold for avalanche activity.The last system brought light accumulations across the region barely covering a variety of old surfaces: a crust exists wind scoured north and northeast slopes and surface hoar can be found in sheltered locations above 1900m. These layers could become reactive over the weekend as the overlying slab develops due to additional snow, wind loading and rising temperatures.A few crusts can be found near the ground, especially at higher elevations. The recent cold temperatures may have weakened the snow around these crusts - especially in alpine areas with a thinner snowpack such as moraine features.Overall the coastal snowpack is significantly thinner than the historical average for this time of year. Early season riding hazards such as rocks, stumps and logs are lurking below the surface at treeline elevations. In glaciated terrain the forecast snow might just be enough to hide open crevasses where supportive snow bridges have not yet developed.

Problems

Storm Slabs

Storm Slab avalanches are the release of a cohesive layer (a slab) of new snow that breaks within new snow or on the old snow surface. Storm-slabs typically last between a few hours and few days (following snowfall). Storm-slabs that form over a persistent weak layer (surface hoar, depth hoar, or near-surface facets) may be termed Persistent Slabs or may develop into Persistent Slabs.

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.