Avalanche Forecast

Archived

Mar 12th, 2023–Mar 13th, 2023

Alpine

Natural and human triggered avalanches likely.

Treeline

Natural avalanches possible, human triggered probable.

Below Treeline

Natural avalanches possible, human triggered probable.

Alpine

Natural avalanches possible, human triggered probable.

Treeline

Natural avalanches possible, human triggered probable.

Below Treeline

Natural avalanches possible, human triggered probable.

Alpine

Natural avalanches possible, human triggered probable.

Treeline

Natural avalanches possible, human triggered probable.

Below Treeline

Natural avalanches unlikely, human triggered possible.

Regions

South Coast Inland, Birkenhead, Duffey, South Chilcotin, Stein, Taseko.

UPDATED ON MONDAY AT 6:25 AM: Less snow fell overnight than expected, but the latest storm system to hit our region may have created reactive storm slabs. Use conservative decision-making until the snow settles.

Confidence

Moderate

Avalanche Summary

On Saturday there were reports of two wind slab avalanches. One was triggered by a rider and the other one went naturally. These occurred in the alpine on north to northeast aspects and at a depth of 20 to 25 cm.

Snowpack Summary

Sunday night's storm may add another 20 to 30 cm to our snowpack. In sheltered areas, this new snow will rest on various amounts of low-density snow that fell earlier in the week. New and old wind slabs can be found near ridge crests in the alpine and treeline. Recent winds have also formed large cornices.

The mid-snowpack is well consolidated.

This is not the case for the lower snowpack. There is a widespread weak layer of large sugary facets at the bottom of the snowpack. Recent avalanche activity on this layer has been confined to northern parts of the region in the Chilcotins. This layer remains a concern in shallow snowpack areas.

Weather Summary

Sunday Night

Cloudy, 15 to 20 cm accumulation, winds southwest 20 km/h gusting to 55, treeline temperatures -5 °C with freezing levels to 1000 m.

Monday

Cloudy, 8 to 12 cm accumulation, winds southwest 25 km/h gusting to 55, treeline temperatures -5 °C with freezing levels at 1200 m.

Tuesday

A mix of sun and cloud, up to 4 cm accumulation, winds southwest 15 to 20 km/h gusting to 50, treeline temperatures -6 °C with freezing levels reaching 1100 m.

Wednesday

A mix of sun and cloud, no accumulation, winds southwest 10 to 15 km/h, treeline temperatures around -5 °C.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

Watch for fresh storm slabs building throughout the day.
Be carefull around freshly wind loaded features.
Pay attention to cornices and give them a wide berth when traveling on or below ridges.
Closely monitor how the new snow is bonding to the crust.
The more the snow feels like a slurpy, the more likely loose wet avalanches will become.

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.