Avalanche Forecast

Issued: Apr 14th, 2013 4:00PM

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

garth lemke, Parks Canada

Jasper.

Observations and cool temperatures are supporting a relatively stable snowpack but evaluate each slope as local variations exist.

Summary

Weather Forecast

Weather will be stable the next few days. Monday into Tuesday evening will be scattered flurries, minimal snow, light N and E winds, cool nighttime and daytime temperatures, and afternoon freezing level rising to 1100m. Wind direction will shift W Tuesday night with no significant weather change indicated other than a gradual temperature increase.Â

Snowpack Summary

Windslabs exist on the lee aspects of exposed ridgecrests above treeline with a dusting of snow overtop. Buried temperature crusts exist below 2100m and sun crusts on steep solar aspects at various elevations. Cornices are big and looming. Gusting 105km/hr N winds last night reverse loaded pockets with the limited snow available.

Avalanche Summary

No new avalanches reported. Several cornice failures occurred last week. A few triggered deep persistent slabs with crowns up to 1m and some initiated wind slabs with a depth of 10-40cm.

Confidence

Wind speed and direction is uncertain

Problems

Wind Slabs

Winds continue forming windslabs on lee aspects below ridgecrests. These slabs sit on previous crusts. Suspect it remains possible for a skier to initiate this slab where it bonds poorly to the underlying crust. N winds reverse loading pockets.

The recent snow may now be hiding windslabs that were easily visible before the snow fell.Carefully evaluate big terrain features by digging and testing on adjacent, safe slopes.

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

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

1 - 3

Cornices

Cornices are large being a hazard by their sheer mass. They can also trigger deeper layers if failure occurs. Several cornice failures were observed last week. Some initiated storm slabs and a few deeper releases.

Do not travel on slopes that are exposed to cornices overhead.

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

Elevations: Alpine.

Likelihood

Unlikely - Possible

Expected Size

1 - 3

Valid until: Apr 15th, 2013 4:00PM