Avalanche Forecast

Issued: Nov 21st, 2012 9:32AM

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

robert hemming, Parks Canada

Glacier.

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Summary

Weather Forecast

Unstable convective snow showers today, possibility of rain below 1100m, moderate to strong SW winds at times. Drier and cooler tomorrow, freezing levels lowering to surface.

Snowpack Summary

Now over 80mm of load on the Nov 6 crust, down 60-80cm from the surface. Sudden planar results are being reported on this layer in the Asulkan Drainage recently. A storm slab is reactive where it overlies the Nov 16 sun crust which can be found in the upper snow pack on steep southerly aspects.

Avalanche Summary

Several new avalanche events to size 3 where observed yesterday above the highway corridor on running to 3/4 fan.

Confidence

Due to the number and quality of field observations

Problems

Storm Slabs

The storm slab continues to evolve. Reports of shooting cracks and planar test results up the Asulkan at treeline recently indicate that rider triggering is possible on the right piece of terrain- a convex or unsupported slope.

Assess start zones carefully and use safe travel techniques.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible - Likely

Expected Size

1 - 3

Wind Slabs

Moderate to strong S-SW winds are redistributing available storm snow, forming windslabs on exposed lee slopes.

Assess start zones carefully and use safe travel techniques.Avoid freshly wind loaded features.

Aspects: North, North East, East.

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 3

Valid until: Nov 22nd, 2012 8:00AM