Avalanche Forecast

Issued: Nov 27th, 2012 3:00PM

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

jeremy.mackenzie, Alberta Parks

Kananaskis.

Sporadic large avalanches have occurred over the past few days including a recent slide on the Rae Glacier. The Nov rain crust will plague us for some time yet. Alpine areas are seeing highly variable wind affect giving some good skiing and some not.

Summary

Confidence

Good

Weather Forecast

Winds will shift to the west and continue in the moderate range at ridgetop. A weak system of precipitation is expected to begin early Thursday morning bringing only a few cm's of snow.

Avalanche Summary

A few loose snow slides up to size 1.0 were observed on steep N and E aspects in the alpine. A large slab avalanche on the Rae Glacier appears to have a fracture line of approximately 150cm deep and occurred on a NE aspect at 2700m. This slide failed on glacial ice and ran down to the middle of the glacier.

Snowpack Summary

Several snow profiles today confirmed that the Nov rain crust is alive and well sitting an average of 35cm off the ground. Compression tests were producing results below the rain crust in the moderate range. There is also evidence of on-going wind slab formation in the alpine, but his is not present in all locations. See snow profile from Three Isle Lake.

Problems

Wind Slabs

Pockets of wind slab are present in lee and cross loaded features in the alpine and isolated areas at treeline. NW winds over the past few days are loading S and SE aspects. A few cornice failures have also been observed.

Be very cautious with gully features.>Be careful with wind loaded pockets while approaching and climbing ice routes.>Avoid lee and cross-loaded terrain near ridge crests.>

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

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

2 - 5

Persistent Slabs

The Nov rain crust persists about 30cm off the ground throughout the forecast area and is reactive to stability tests in the moderate range. Avalanches in the upper snowpack may step down to this weakness.

Be aware of the potential for full depth avalanches due to deeply buried weak layers.>Whumpfing is direct evidence of a buried instability.>

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

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

3 - 5

Valid until: Nov 28th, 2012 2:00PM