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Avalanche Forecast

Archived

Mar 9th, 2023–Mar 10th, 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.

Enjoy the snow but be alert when transitioning into wind-affected terrain.

Avoid steep, rocky, and shallow snowpacks to lessen your chance of triggering buried weak layers.

Confidence

Moderate

Avalanche Summary

On Thursday, the results of a natural cornice failure were observed in the Core Lodge area. It was on a rocky northeast aspect and it did not produce an avalanche on the slope below and was thought to be about 24 hours old.

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.

Snowpack Summary

Shifting winds have redistributed any available snow into wind slabs on a variety of aspects. There is a good chance that the wind has stripped the snow away in the alpine and wind slabs could be found at treeline. In sheltered areas, soft storm snow from last week can be found and will be resting on heavily wind-affected snow. This MIN has some great photos showing this.

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

Thursday Night

Clear with increasing clouds, no accumulation, winds southeast 20 km/h, treeline temperatures around -10 °C.

Friday

Cloudy with sunny periods, trace accumulation, winds northeast 15 km/h ramping up to 45 by afternoon, treeline temperatures around -15 °C.

Saturday

Cloudy with sunny periods late in the day, trace accumulation, winds easterly 15 to 25 km/h gusting to 40, treeline temperatures -20 to -15 °C.

Sunday

Cloudy with sunny periods, trace accumulation, winds easterly 20 to 30 km/h gusting to 40, treeline temperatures around -10 °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.