Avalanche Forecast

Issued: Feb 21st, 2015 3:00PM

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

jeremy.mackenzie, Alberta Parks

Kananaskis.

Watch for recent storm slabs and older wind slabs that will be more triggerable in steep terrain. The sun is starting to pack a punch so be mindful of exposure to solar aspects as the days heat up.

Summary

Confidence

Good

Weather Forecast

A mix of sun and cloud over the next couple of days with little in the way of precipitation. Temperatures will be fairly mild with freezing levels at 1700m on Sunday and 2200m on Monday. Winds are expected to be light out of the N or NW.

Avalanche Summary

Two size 2.0 naturally triggered slabs were observed today on steep SW aspects in the Alpine. These were only approximately 20cm deep but had wide propagations of over 100 metres. Very small loose dry slides were also observed in very steep Alpine terrain on all aspects.

Snowpack Summary

Up to 15cm of new snow overnight, with less at valley bottom. This snow has formed into soft storm slabs in exposed Alpine terrain and open areas at treeline. Much of these new storm slabs are found in "traditional" lee and cross-loaded features, but recent moderate NE winds have also put these slabs on S and SW aspects. Otherwise the snowpack remains much the same, dominated by numerous crust layers and very weak basal layers.

Problems

Wind Slabs

In the Alpine and open areas at Treeline there is still a wind slab of concern with the failure plane down 60 to 90cm. Watch for this problem in steeper terrain at higher elevations.

Watch for areas of hard wind slab in steep alpine features.>Choose well supported terrain without convexities.>

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

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 3

Storm Slabs

Recent snow and winds, including some "reverse wind loading" from Northerly winds, have created storm slabs 20 to 30cm thick. These slabs are sensitive to human triggering and some natural activity up to size 2.0 occurred on steep SW aspects today.

Stay off recent wind loaded areas until the slope has had a chance to stabilize.>Avoid travelling in areas that have been reverse loaded by winds.>Caution in lee and cross-loaded terrain near ridge crests.>

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

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 3

Deep Persistent Slabs

Weak basal layers are prominent throughout the forecast area. While the probability of triggering the basal layers is less likely, the consequences are large.

Be aware of thin areas that may propogate to deeper instabilites.>Be aware of the potential for large, deep avalanches.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

3 - 5

Valid until: Feb 22nd, 2015 2:00PM