Avalanche Forecast

Issued: Nov 18th, 2012 8:25AM

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

jeremy.mackenzie, Alberta Parks

Kananaskis.

Up to 25cm of new snow Monday, with an additional 30+cm on Tuesday. Winds will remain strong from the SW. If this weather forecast comes true, a large natural avalanche cycle is expected to occur. It is time for very conservative terrain selection!

Summary

Confidence

Fair - Timing of incoming weather is uncertain

Weather Forecast

Another 25cm or more possible on monday with an additional 30cm+ on Tuesday. Strong to extreme winds from the SW will continue.

Avalanche Summary

Limited observations due to variable visibility, but did see a few skier triggered slabs up to size 1.0 that were 30cm thick on average.

Snowpack Summary

15 to 20cm of new snow overnight forming soft and hard wind slabs in alpine and treeline locations, especially on N and E aspects. Moderate shears exist down 17cm and 23cm. Three separate crusts layers make up the midpack, with moderate to hard test results failing below these different crusts. Total height of snow at 2200m was 70cm.

Problems

Storm Slabs

Intense wind loading is occurring on lee and cross loaded features due to strong SW winds and ongoing precipitation. Slab formation was noted today and cracking was observed. Ski cutting produced small slabs failing on the Nov rain crust.

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

Elevations: Alpine, Treeline.

Likelihood

Very Likely

Expected Size

2 - 6

Persistent Slabs

Previously formed wind slabs are now getting hidden by the new snow. These persistent slabs will become more sensitive to human triggering as load is added. These slabs are also failing on the Nov rain crust and are prominent in gully features.

Aspects: North, North East, East.

Elevations: Alpine, Treeline.

Likelihood

Likely - Very Likely

Expected Size

2 - 5

Loose Dry

Steep lee and cross loaded features in the alpine are areas to watch for loose dry slides. Gully features, such as many ice climbs, should be treated with caution.

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

Elevations: Alpine, Treeline.

Likelihood

Likely - Very Likely

Expected Size

1 - 4

Valid until: Nov 19th, 2012 8:00AM