Avalanche Forecast

Issued: Mar 17th, 2015 3:00PM

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

jeremy.mackenzie, Alberta Parks

Kananaskis.

Recently formed slabs remain sensitive to human triggering at higher elevations. Also, be mindful of solar radiation and its destabilizing effect on the snowpack on solar aspects.

Summary

Confidence

Good

Weather Forecast

A mix of sun and cloud expected on Wednesday with temperatures near -2 celsius in the alpine. Winds will be out of the NW at 25 to 45km/h with freezing levels near 2000m. A new system will push in Thursday bringing strong winds, cloudy skies and light precipitation.

Avalanche Summary

Several solar triggered sluffs up to size 2.0 observed today in the alpine. A few slab avalanches up to size 2.0 were also observed in steep alpine terrain on all aspects. These slabs involved only the storm snow.

Snowpack Summary

The snowpack is highly variable depending on aspect and elevation. Storm snow from last weekend has settled out to 40cm at treeline. The interface beneath this storm snow continues to give moderate sudden planar results in snowpack tests on polar aspects. Some areas at upper treeline elevations have a thin buried slab above this interface that was formed early in the storm. Wind speeds decreased dramatically at the end of the storm leaving mainly low density snow above these thin slabs. More extensive slab formation occurred in the alpine and several recent avalanches can be associated to this issue. On solar aspects a completely different situation exists. The storm snow is settling rapidly and appears well bonded to the previous surface of sun crust, except at higher elevations in the alpine where the bond seems less solid. Snow was again turning moist on the surface today in steep terrain on all solar aspects. On all aspects below 2100m the recent snow sits on a very dense and strong rain crust about 1cm thick.

Problems

Storm Slabs

Storm snow totals are now near 40cm at treeline and soft slabs are present in the alpine and open areas at treeline. The interface beneath these slabs is giving moderate results in snowpack tests, indicating the human triggering is possible.

Avoid lee and cross-loaded terrain near ridge crests.>Assess start zones carefully and use safe travel techniques.>

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

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

2 - 4

Loose Wet

The mid-March sun is intense and has been causing loose wet avalanches on solar aspects for the last couple of days. Carefully evaluate your exposure to these features and be aware of overhead terrain.

Avoid sun exposed slopes when the solar radiation is strong, especially if snow is moist or wet.>Be cautious of sluffing in steep terrain.>Avoid travelling under cliffs that are exposed to sluffing from above.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1 - 3

Deep Persistent Slabs

The recent new load of snow could be enough to awaken the basal weak layers, particularly in shallow snowpack areas.

Avoid convexities or areas with a thin or variable snowpack.>Be aware of the potential for full depth avalanches due to deeply buried weak layers.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely

Expected Size

2 - 5

Valid until: Mar 18th, 2015 2:00PM