Avalanche Forecast

Issued: Dec 18th, 2018 4:10PM

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.

michael.olsthoorn, Alberta Parks

Kananaskis.

Lots of new snow has recently fallen. Be cautious when approaching bigger slopes as weak layers are present in the snowpack.

Summary

Confidence

Moderate - Due to the number of field observations

Weather Forecast

Another 10cm of snow has fallen during the day on Tuesday to bring our storm snow up to 35-45cm. Wednesday will bring another 10cm of snow with 30km/hr SW winds with gusts up to 50km/hr and temperatures around -7c. The weather models for Thursday show more snow with moderate winds. Cooler temperatures are expected for the weekend.

Avalanche Summary

One natural avalanche size 1.5 was observed in the Burstall Pass area. Keep in mind that human triggering is still likely.

Snowpack Summary

This recent storm has left us with 35-45cm of snow in sheltered areas and up to 90cm of storm snow in lee features. These loaded lee features are a good indication of the recent wind transport; it will be important to look for windslabs before venturing into bigger terrain. Below this storm snow are surface hoar and facet crystals which are creating a weak sliding surface for the snow to be reactive; we are calling this the December facet layer interface and it is producing easy to moderate failures in our snow tests. There is still concern for this recent storm snow to trigger the October facet layer at the bottom of the snowpack.

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.

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

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

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

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1.5 - 3

Valid until: Dec 19th, 2018 2:00PM