Avalanche Forecast

Issued: Mar 19th, 2012 4:00PM

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

jeremy.mackenzie, Alberta Parks

Kananaskis.

15 to 20cm of new snow is possible through Tuesday with up to 100km/h winds. Pay attention to localized conditions as the danger could rise to HIGH if more snow falls than is expected. Storm slabs will be increasingly sensitive to human triggering.

Summary

Confidence

Fair - Intensity of incoming weather is uncertain

Weather Forecast

A relatively cool day on Tuesday with 15 to 20cm of new snow possible. Winds are expected to be from the SW and increase through the day to 100km/h.

Avalanche Summary

One natural avalanche was observed near midday today. It began as a loose snow avalanche which triggered a size 2.0 slide on the underlying slopes on an E aspect in the alpine. A few other recent slides (24 to 48 hours old) have occurred on steep N, NE and E aspects primarily in treeline and alpine features. These slides mostly ran full path, with some snapping off small trees.

Snowpack Summary

An additional 2 to 3cm of new snow overnight at treeline. Storm snow totals are near 40cm at ridgetop. Soft slabs are present in alpine and treeline areas. A few recent avalanches up to size 2.5 are associated with the recent storm slabs. February surface hoar is down as much as 140cm and while more difficult to trigger, the consequences are large. The surface hoar is also susceptible to step down triggering. Cornices are quite large. The deep persistent weak layer of facets and depth hoar has been less active recently, but the possibility remains for a large destructive full depth avalanche if these layers are triggered.

Problems

Storm Slabs

Storm slabs up to 40cm thick are present along ridgelines and in crossloaded features at treeline and above. Avalanches starting in the upper snowpack will likely step down to one of the deeper layers. Recent avalanches have occurred on this layer.

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

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1 - 5

Persistent Slabs

Surface hoar buried up to 150cm continues to be a major concern in the snowpack. A dense slab now sits on top of this layer. Avalanches in the upper snowpack will likely step down to this layer causing a destructive avalanche.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible - Likely

Expected Size

2 - 6

Persistent Slabs

The March 11th Temperature crust is buried down 50cm on solar aspects. The bond of the upper snowpack to this crust is highly variable and requires careful evaluation as you travel.

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

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 4

Cornices

Cornices have grown significantly in the alpine. Failures continue to occur and have triggered avalanches up to size 3 on the underlying slopes. Give cornices a wide berth and stay well back from corniced ridge crests.

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

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

2 - 6

Deep Persistent Slabs

The weak basal facets and depth hoar are still present. Large terrain features are areas of concern where a smaller slide could step down and trigger a very large avalanche with deep and wide propagation.

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

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

3 - 7

Valid until: Mar 20th, 2012 9:00AM