Avalanche Forecast

Issued: Nov 27th, 2012 4:00PM

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.

garth lemke, Parks Canada

Jasper.

Features of concern remain: ridgetop transitions with local winds creating surface slabs plus shallow locations where deeper instabilities could be triggered. Despite less natural activity, human triggered avalanches remain possible.

Summary

Weather Forecast

Temperatures will trend cooler the next few days with continued unsettled weather. A few centemetres every day this week with continued light winds. Expect winds to be stronger at some local ridgetop locations or higher alpine elevations.

Snowpack Summary

Minimal wind affect observed and 10-15cm of low density surface snow in most areas. Windslabs can be found in the alpine buried under last week's snow and may be developing at exposed ridgetops. Several small whumphs observed in shallow areas. Winds remain calm for the most part.

Avalanche Summary

Several loose natural point releases observed on in steep rocky terrain did not trigger slopes below. No new slab avalanches have been observed for 3 days. Caution is still warranted despite the decrease in natural activity.

Confidence

Wind effect is extremely variable

Problems

Wind Slabs

No new natural activity on this layer has been noted for a few days yet potential still exists on steep unsupported wind affected slopes. This layer can be found under 10-20cm of recent storm snow, at ridgetops, and where reverse loading occurred.

Avoid exposure to terrain traps where the consequences of a small avalanche could be serious.Avoid freshly wind loaded features.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

1 - 3

Persistent Slabs

Persistent slabs are found in the mid-pack overlying crust or developing facets. Snow load from wind deposition or significant snowfall may increase the likelihood of natural avalanches. Consequences would be severe if skier triggered.

Avoid shallow snowpack areas where triggering is more likely.Be alert to conditions that change with elevation.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

2 - 3

Valid until: Nov 28th, 2012 4:00PM