Avalanche Forecast

Issued: Dec 20th, 2016 3:33PM

The alpine rating is considerable, the treeline rating is considerable, and the below treeline rating is low. Known problems include Storm Slabs, Wind Slabs and Loose Dry.

matt.mueller, Alberta Parks

Kananaskis.

Snow and wind have joined forces to give us a touchier snowpack that what we are used to. Conservative terrain is recommended for the next while.

Summary

Confidence

High -

Weather Forecast

Mainly cloudy tomorrow with little forecasted snow. Don't be surprised if we do get small amounts of fresh snow near the divide. Temperatures will continue to hover around -11. Winds are the real story, expect steady alpine winds of 70 km/hr with significantly higher gusts .

Avalanche Summary

2 separate incidents to talk about today:1) Forecasters remotely triggers a Sz 2 in alpine terrain. As the team walked on the top of a ridge, they triggered a small cornice chunk(10m away) that went on to release the storm slab below. The slab itself was up to 40cm thick and entrained a large amount of snow as it traveled. East aspect, 2400m, a short steep slope with a large fetch.2) A party of 3 scramblers triggered a Sz 2 slab in alpine terrain and went for a ride. Details are largely unknown, but it occurred in typical front range mixed scree/snow terrain near Wind Tower.

Snowpack Summary

Strong alpine and treeline winds have transported a huge amount of snow. Any new snow that fell has been blown into storm slabs. Even the older facetted snow has been blown around to create fresh windslabs. Areas near the divide (Burstall Pass) saw up to 20cm of new snow in the last 24-48 hours. When that fresh snow is combined with wind, slabs up to 60cm thick are common. Open areas at treeline and alpine have a widespread windslab problem and alpine areas have an additional storm slab problem in immediate lees(easterly aspects). It feels as though we are on the verge of a small natural cycle. These slabs appear to be running on the older windslabs, but quickly involving the midpack facets. The mid pack is weak enough that entrainment after the initial failure is a real concern.

Problems

Storm Slabs

These tend to be in the higher, wind prone areas. Upper Treeline & alpine are the likely areas to find these new slabs. Watch overhead exposure and treat any wind loaded slope with respect.

Avoid freshly wind loaded features.Even small avalanches may run a long ways under the current conditions.

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

Elevations: Alpine, Treeline.

Likelihood

Very Likely

Expected Size

2 - 3

Wind Slabs

In the alpine, these slabs are now buried beneath the storm slabs. They will be harder to detect with the new snow texture. Use small terrain to find them and assess them often. Climbers!! Watch for pockets of hard slab on and around routes!

Use caution on open slopes and convex rolls Watch for areas of hard wind slab in steep alpine features.If triggered the wind slabs may step down to deeper layers resulting in large avalanches.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

2 - 3

Loose Dry

Still a concern given our mainly facetted snow pack. Gully features should be avoided. Ice climbers should be very aware of this concern.

Carry avalanche safety equipment on ice climbs in avalanche terrain.Be cautious of sluffing in steep terrain.Avoid travelling on ledges and cliffs where sluffing may have severe consequences.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1 - 2

Valid until: Dec 21st, 2016 2:00PM