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Avalanche Forecast

Archived

Mar 8th, 2023–Mar 9th, 2023

Alpine
Natural avalanches unlikely, human triggered possible.
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.
Alpine
Natural avalanches unlikely, human triggered possible.
Treeline
Natural avalanches unlikely, human triggered possible.
Below Treeline
Natural avalanches unlikely.

Regions

North Rockies, Kakwa, McGregor, Pine Pass, Tumbler.

Don't let good riding lure you into dangerous terrain with overhead hazards.

Triggering large slab avalanches remains possible in steep, rocky, and wind-affected areas.

Confidence

Moderate

Avalanche Summary

No new avalanches reported in the last 24 hours.

Last weekend, there were several natural and human-triggered wind slabs were observed from a variety of aspects in alpine and treeline terrain as northeasterly winds impacted the region. Check out this MIN from Pine Pass on Saturday for an example.

Another MIN report from Pine Pass on Sunday shows a very large deep persistent slab from alpine terrain that was likely triggered by a cornice failure or wind-loading. This is the first observation in several weeks of deep persistent slab activity and is an indication that this layer should be on our radar, particularly in the shallower snowpack parts in the region.

A big shout out to those helping their community by posting in the Mountain Information Network.

Snowpack Summary

Shifting winds have redistributed any available snow into wind slabs on a variety of aspects. In sheltered areas, soft storm snow from last week can be found and will be resting on heavily wind-affected snow.

The middle of the snowpack is generally strong.

A weak layer of large and weak facets is found near the base of the snowpack. This layer is of greatest concern in shallow snowpack areas in the north and east of the region.

Weather Summary

Wednesday Night

Mostly cloudy, trace accumulation, winds easterly 30 km/h, treeline temperatures around -15 to -10 °C.

Thursday

Morning clouds giving way to sun, no accumulation, winds southwest 25 km/h, treeline temperatures -15 to -10 °C.

Friday

Mostly sunny, trace accumulation, winds northeast 15 km, treeline temperatures -12 to -8 °C.

Saturday

A mix of sun and cloud, trace accumulation, winds easterly 10 to 25 km/h, treeline temperatures -20 to -15 °C.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

  • Recent wind has varied in direction so watch for wind slabs on all aspects.
  • Avoid shallow, rocky areas where the snowpack transitions from thick to thin.
  • Use extra caution around cornices: they are large, fragile, and can trigger slabs on slopes below.
  • Minimize exposure to sun-exposed slopes when the solar radiation is strong.

Problems

Wind Slabs

Wind Slab avalanches are the release of a cohesive layer of snow (a slab) formed by the wind. Wind typically transports snow from the upwind sides of terrain features and deposits snow on the downwind side. Wind slabs are often smooth and rounded and sometimes sound hollow, and can range from soft to hard. Wind 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.