Avalanche Forecast

Issued: Mar 28th, 2017 3:05PM

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

jeremy.mackenzie, Alberta Parks

Kananaskis.

Natural avalanche activity is subsiding and hazard ratings are slowly dropping, but it is still possible to have full path avalanches. An Avalanche Canada BLOG explores this issue.

Summary

Confidence

Moderate - Freezing levels are uncertain

Weather Forecast

Wednesday will be mainly cloudy with isolated flurries and Alpine temperatures near -5 °C. Winds will be moderate from the SW, and the freezing level will climb to 2000 metres. Thursday looks to be a mostly sunny day with light winds and high freezing levels.

Avalanche Summary

One naturally triggered size 1.0 wind slab was observed on a NE aspect at 2300m. This slab was only 15cm thick and did not run far. Also, a size 1.5 cornice failure was observed on a N aspect at 2700m. This cornice failed at approximately 14:00hrs and did not propagate a slab on the underlying slopes.

Snowpack Summary

Up to 5cm of new snow in the past 24hrs. In sheltered areas there is now 25cm of low density snow overlying previous surfaces. On solar aspects there are now various buried crusts. Strong winds today led to further wind slab development in the Alpine and isolated areas at Treeline. Easy shears were observed down 10 and 25cm. The snow was moist this afternoon below 1900m. The middle of the snowpack is generally well settled and dense, while the base of the snowpack consists of over 100cm of depth hoar and facets. Natural avalanche activity has tapered off, but the structure of the snowpack continues to cause concern to forecasters for "low probability, high consequence" avalanches.

Problems

Wind Slabs

Wind slabs are present in the Alpine and isolated areas at Treeline. Easy shears were found down 10 and 25cm today on a wind exposed ridge feature.

Be careful with wind loaded pockets, especially near ridge crests and roll-overs.

Aspects: All aspects.

Elevations: Alpine.

Likelihood

Possible - Likely

Expected Size

1 - 3

Deep Persistent Slabs

Due to the nature of the snowpack, forecasters still have very little confidence in larger terrain features, particularly in the Alpine. Full depth avalanches that could reach the end of run out zones are still possible.

Pay attention to overhead hazards like cornices which could easily trigger the deep persistent slab.Avoid exposure to overhead avalanche terrain, large avalanches may reach the end of run out zones.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Unlikely - Possible

Expected Size

2 - 4

Cornices

The March sun is strong and cornices will become more fragile during sunny and/or warm periods. Having said this, sun isn't the only trigger, as forecasters observed a cornice failure today under cloudy and windy conditions.

Cornices become weak with daytime heating. Pay attention to overhead hazards like cornices which could easily trigger deep slabs.

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

Elevations: Alpine.

Likelihood

Possible

Expected Size

2 - 3

Valid until: Mar 29th, 2017 2:00PM