Avalanche Forecast

Issued: Mar 20th, 2013 9:13AM

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

jeremy.mackenzie, Alberta Parks

Kananaskis.

Storm slabs in Alpine and Treeline areas remain touchy, with continued avalanche activity observed today. The danger level could rise to HIGH in specific locations if more snow falls than expected. Complex snowpack and weather conditions exist.

Summary

Confidence

Fair - Timing, track, or intensity of incoming weather is uncertain

Weather Forecast

Thursday will bring strong westerly winds with ridgetop temperatures near -13. Light snow is expected with accumulations likely between 10 and 20cm.

Avalanche Summary

Tent Bowl produced a size 2.5 slab avalanche sometime in the last 12 hours. See Facebook for photos. This slide took out a good portion of the normal ski line and also ran over the up-track well down into the gully. Another size 2.0 cornice triggered slide was observed on an E aspect at 2400m. Some isolated snow-balling was also observed on steep solar aspects in the afternoon.

Snowpack Summary

Up to 2cm of new snow fell overnight. The snowpack continues to settle. Moist snow observed on solar aspects in the afternoon up to at least 2200m. Touchy storm slabs are widespread in Alpine and Treeline terrain on all aspects. Numerous crust layers exist in the upper snowpack up to 2300m on all aspects and as high as 3000m on S aspects.

Problems

Storm Slabs

Storm slabs averaging 40cm thick are present on all aspects in the Alpine and open areas at Treeline. In some cases the slabs sit on a crust layer. These slabs have produced a few recent large avalanches and are sensitive to human triggering.

Avoid exposure to overhead avalanche terrain, as large avalanches may reach the end of runout zones.>Avoid freshly wind loaded features.>Choose well supported terrain without convexities.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

2 - 5

Cornices

Significant cornice growth has occurred recently and several cornice failures have occurred in the past couple of days. These cornice failures are triggering avalanches on the underlying slopes.

Pay attention to overhead hazards like cornices.>Avoid exposure to overhead avalanche terrain, as large avalanches may reach the end of runout zones.>

Aspects: North, North East, East.

Elevations: Alpine.

Likelihood

Possible - Likely

Expected Size

1 - 5

Persistent Slabs

Several crust layers are found in the upper snowpack. These crusts reach as high as 3000m on S aspects and between 22-2400m on other aspects. Carefully evaluate the bond at these interfaces and be cautious during times of solar radiation.

Avoid convexities or areas with a thin or variable snowpack.>Be aware of the potential for full depth avalanches due to deeply buried weak layers.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible

Expected Size

2 - 4

Valid until: Mar 21st, 2013 2:00PM