Avalanche Forecast

Issued: Feb 24th, 2017 3:13PM

The alpine rating is considerable, the treeline rating is moderate, and the below treeline rating is low. Known problems include Wind Slabs, Persistent Slabs and Deep Persistent Slabs.

jeremy.mackenzie, Alberta Parks

Kananaskis.

Natural avalanche activity has largely subsided, but the potential for human-triggering remains. Due to the weak basal structure of the snowpack, very large avalanches are possible. Conservative route selection is advised.

Summary

Confidence

High -

Weather Forecast

The next few days will be cool (highs near -15 °C) with light flurries. Snow accumulations are not expected to be significant. Winds will be moderate from the West on Saturday and then switch to light from the East on Sunday.

Avalanche Summary

Nothing new today, but some large naturally triggered avalanches have occurred over the past week.

Snowpack Summary

Recent storm snow has settled to an average of 20cm deep, with very little wind effect in most areas below 2500m. On steep solar aspects there is a buried suncrust (Feb 17th layer) down 20-30cm. Beneath this, the upper snowpack remains well settled with denser slabs as the 50cm depth is reached. The basal layers are alive and well and vary between 30-50cm thick, and is a dog's breakfast of crusts, facets and depth hoar. Snowpack stability tests today indicate a sudden collapse failure within the basal layers in the moderate range. These tests were done in a slightly shallower morainal feature, and indicate the possibility of full-depth avalanches if the "sweet spot " is triggered.

Problems

Wind Slabs

These slabs are now lightly buried under the new snow from the last few days. So far these have been an issue in steep convex terrain and below cliffs. Cross-loaded areas at treeline also have the slabs, however these are a bit more stubborn.

Avoid lee and cross-loaded terrain near ridge crests.If triggered the wind slabs may step down to deeper layers resulting in large avalanches.

Aspects: North, North East, East, South East, South.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 2

Persistent Slabs

Triggering this layer is still a possibility in thin areas. Expect large propagations.

Be aware of the potential for wide propagations.Minimize exposure to overhead avalanche terrain, large avalanches may reach run out zones.

Aspects: North, North East, East, South East, South.

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

2 - 3

Deep Persistent Slabs

We are approaching the "low probability, high consequence" phase of the winter. Respect the potential for this layer to react to large triggers, or weak shallow areas.

Avoid exposure to overhead avalanche terrain, large avalanches may reach the end of run out zones.Avoid steep convexities or areas with a thin or variable snowpack.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Unlikely - Possible

Expected Size

2 - 4

Valid until: Feb 25th, 2017 2:00PM