Avalanche Forecast

Issued: Dec 17th, 2018 3:00PM

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

jeremy.mackenzie, Alberta Parks

Kananaskis.

Hazard levels could be higher than forecast if the snowfall arrives earlier than expected. Backcountry users should keep a close eye on local conditions.

Summary

Confidence

Moderate - Forecast snowfall amounts are uncertain

Weather Forecast

Tuesday and Wednesday will remain primarily windy (up to 90km/h from the SW), with daytime high temperatures near -7. When it comes to snowfall amounts there is significant disagreement between the models, with the most "optimistic" calling for 25cm by Wednesday evening.

Avalanche Summary

Natural avalanche activity has tapered off, but recent slides up to size 2.5 have been observed in the Alpine and Treeline elevation bands. Keep in mind that human triggering is still likely.

Snowpack Summary

A few convective flurries through the day on Monday put a light dusting on the surface. Recent storm snow has settled to an average of 40cm at Treeline. Widespread wind slabs are present in Alpine and Treeline terrain in lee and cross-loaded features. There has been lots of cracking, whumpfing, and skier triggered avalanches on the Dec 10th surface hoar and facet interface down 40-50cm. In addition, recent natural avalanches have stepped down to the October crust with fracture depths over 1 metre in some cases.

Problems

Wind Slabs

There is still concern for human-triggering of wind slabs with the failure plane down 30 to 50cm at Treeline and deeper in the Alpine.

Use conservative route selection, choose moderate angled and supported terrain with low consequence.If triggered the storm/wind slabs may step down to deeper layers resulting in large avalanches.Avoid freshly wind loaded features.

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

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 2.5

Deep Persistent Slabs

The basal layers are very weak, even by Rockies standards. Any avalanche triggered in the upper snowpack is likely to step down to the basal layers. Extra caution is required to manage this avalanche problem.

Be cautious in shallow snowpack areas where triggering is more likely.Avoid unsupported slopes.Be aware of the potential for full depth avalanches due to weak layers at the base of the snowpack.

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

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1.5 - 3

Valid until: Dec 18th, 2018 2:00PM