Avalanche Forecast

Issued: Nov 24th, 2012 4:00PM

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

max darrah, Parks Canada

Jasper.

Good skiing can be found in sheltered areas, but careful snowpack evaluation is necessary to determine if there are previous wind slabs buried under the new snow.

Summary

Weather Forecast

Scattered light precipitation expected through the weekend with light westerly winds. Freezing levels to stay low and temps consistent in the -5 to -10 range.

Snowpack Summary

10cm in the past 24 hours brings the 5 day total to over 50cm at treeline elevation. This is a significant load on the November snowpack and may increase the likelihood of triggering persistent slabs that are buried under storm snow. New windslabs can be found on exposed Northerly aspects.

Avalanche Summary

Marmot Basin reported several new natural slab avalanches on North aspects above 2200m. These slabs were roughly 10-30cm thick and in the size 1-2.5 range.

Confidence

Due to the number of field observations

Problems

Wind Slabs

Numerous natural slab avalanches have been observed in the past 48hrs, mostly in wind loaded features above 2300m. The predominant Southerly winds make the Northern aspects the prime suspect for new windslab formation.

Be cautious as you transition into wind affected terrain.Avoid lee and cross-loaded terrain near ridge crests.

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

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 3

Persistent Slabs

Previous wind slabs can be found buried beneath the recent storm snow on lee aspects in exposed terrain.

The recent snow may now be hiding windslabs that were easily visible before the snow fell.

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

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 3

Valid until: Nov 25th, 2012 4:00PM