Avalanche Forecast

Issued: Dec 27th, 2012 4:08PM

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

Parks Canada A.L. Horton, Parks Canada

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Jasper.

Small loose snow avalanches are common on steep tree line and alpine slopes.  These slides are thin but traveling far.  Evaluated slopes and ice climbs before committing. 

Summary

Weather Forecast

Temperatures nearing the freezing level at valley bottoms on Friday.  The moderate to strong westerly winds are expected to continue until they ease on Friday night.  Expecting cloudy skies with light precipitation and little accumulation.

Snowpack Summary

Moderate to strong SW winds continue to build slab conditions on open tree line slopes and along ridge lines in the alpine.  The mid-pack is facetting but remains strong where it is deeper than a meter.  In shallow areas, facetting has weakened it significantly.

Avalanche Summary

Surface facets have created numerous small loose avalanches at tree line and above in the Icefields area.  These slides have little mass and have not as yet triggered the wind slabs beneath them.  No natural slab avalanches were observed today.

Confidence

Due to the number and quality of field observations

Problems

Wind Slabs

An icon showing Wind Slabs
Moderate to strong westerly winds continue to build wind slab conditions on slopes and along ridge lines.  No avalanche activity was observed on this developing condition, however, we have not tested the bonding strength.

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

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

1 - 3

Deep Persistent Slabs

An icon showing Deep Persistent Slabs
On Wednesday, small natural slab avalanches to size 1.5 were observed on the basal facets in thin snowpack areas.  Triggering is most likely to happen along edges of shallow pockets and from thin spots like rocks or trees.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible

Expected Size

1 - 3

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

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