Avalanche Forecast

Issued: Feb 10th, 2015 3:00PM

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

jeremy.mackenzie, Alberta Parks

Kananaskis.

Conditions are still ripe for human triggering at Treeline and above. Many clues of unstable snow have been observed in recent days. Give the snowpack more time to stabilize before committing to bigger terrain features.

Summary

Confidence

Fair - Freezing levels are uncertain

Weather Forecast

Wednesday will be a mix of sun and cloud and very light flurries with temperatures near -4 in the Alpine. Winds will be out of the West at 30km/h and the freezing level will climb to 1900m. Thursday and Friday will see warm temperatures and rising freezing levels.

Avalanche Summary

A significant natural avalanche cycle has occurred over the last 4 days. Some ski-triggered slides have also been reported. Activity has tapered off, but 2 new naturally triggered slabs were observed today on E aspects between 2300 and 2600m. These slabs were both size 2.0 and appeared to be storm snow slabs.

Snowpack Summary

12cm of new snow overnight brings recent storm snow totals to between 50 and 70cm at Treeline. This storm snow is generally settling rapidly due to mild temperatures. Wind slabs are present in open areas at Treeline and in the Alpine and these have been reactive to ski cutting in recent days and are also giving easy to moderate results in compression tests. Storm slabs are also an issue at all elevations with the interface (down 50 to 70cm) giving moderate compression test results today with very clean shear qualities. The surface snow is moist below 2050m on all aspects and higher on solar aspects. The snowpack in the valley floor did freeze overnight, but by midday the snowpack was moist and unsupportive. Recent cornice growth is also a concern as failures of cornices have triggered the deep persistent weak layer of the November facets in very large avalanches in recent days.

Problems

Wind Slabs

Touchy wind slabs can be found in open areas at Treeline and in the Alpine. Recent ski cutting indicates that these slabs are sensitive to human triggering.

Avoid lee and cross-loaded terrain near ridge crests.>Choose well supported terrain without convexities.>

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

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 4

Storm Slabs

Whumpfing has been observed over the last few days indicating that the storm slab is reactive to human triggering. This interface is highly variable across the forecast region, so diligent route-finding and conservative terrain selection is advised.

Watch for whumpfing, hollow sounds, shooting cracks or recent avalanches.>Avoid runouts where triggering slopes from below is possible.>Avoid freshly wind loaded features.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible - Likely

Expected Size

2 - 4

Deep Persistent Slabs

Large loads, such as cornices, may trigger the weak basal layers producing very large avalanches.

Be aware of the potential for full depth avalanches due to deeply buried weak layers.>Be aware of thin areas that may propogate to deeper instabilites.>Pay attention to overhead hazards like cornices.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

3 - 6

Valid until: Feb 11th, 2015 2:00PM