Avalanche Forecast

Issued: Apr 4th, 2017 3:00PM

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

jeremy.mackenzie, Alberta Parks

Kananaskis.

Still some deep weak layers to be concerned with. And the transition to Spring has slowly begun - avalanche hazard will increase with solar radiation and daytime heating. Keep an eye on localized conditions.

Summary

Confidence

Moderate - Freezing levels are uncertain

Weather Forecast

Wednesday is expected to be mainly cloudy with no precipitation. Winds will be 30km/h from the SW at ridgetop with Alpine temperatures near -3 C. Freezing levels should reach 2200m. Thursday and Friday may be warmer yet and should see a bit of sun mixed with light flurries.

Avalanche Summary

One size 1.5 cornice failure occurred on Mt Buller in the past 24hrs, but the cornice did not trigger a slab on the underlying slopes. A few solar triggered loose wet avalanches up to size 2.0 were observed in steep Alpine and Treeline terrain today.

Snowpack Summary

A clear and cold night brought a good surface freeze to the snowpack overnight, but that changed quickly on steep solar aspects where snow was moist by late morning. Solar aspects have a variety of buried crusts, whereas polar aspects above 2100m have an average of 20cm of dry snow sitting on a variety of previous surfaces. Wind slabs are present everywhere in the Alpine except in sheltered features. Not much natural avalanche activity has occurred with these wind slabs, but many areas like ripe for human-triggering. As previously reported the mid-pack remains dense and strong, but the basal layers are very weak consisting of anywhere between 50 and 100cm of facets sitting on the ground. Forecasters still have low confidence for traveling in large Alpine terrain, unless there has been widespread previous avalanching.

Problems

Deep Persistent Slabs

We know it sounds like a broken record, but this deep layer is still a threat in any avalanche terrain that has not yet had extensive previous avalanching. While there is a lower probability of triggering, the consequences are high.

Avoid exposure to overhead avalanche terrain, large avalanches may reach the end of run out zones.Be wary of slopes that did not previously avalanche.Pay attention to overhead hazards like cornices which could easily trigger deep slabs.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Unlikely - Possible

Expected Size

2 - 4

Loose Wet

The intense April sun is causing a rapid increase in loose wet avalanche activity on solar aspects as the each day progresses.

Avoid slopes when the solar radiation is strong, especially if they have large cornices overhead.Minimize exposure to steep, sun exposed slopes when the solar radiation is strong.

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

Elevations: All elevations.

Likelihood

Likely

Expected Size

1 - 2

Wind Slabs

Not much natural avalanche activity with these wind slabs yet, but human-triggering is more likely in convex and unsupported features. These slabs seem confined to the Alpine.

Avoid cross loaded slopes at or above treeline.Use caution in lee areas. Recent wind loading has created wind slabs.Avoid freshly wind loaded features.

Aspects: All aspects.

Elevations: Alpine.

Likelihood

Possible

Expected Size

1 - 3

Valid until: Apr 5th, 2017 2:00PM