Avalanche Forecast

Issued: Dec 23rd, 2012 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 Deep Persistent Slabs.

garth lemke, Parks Canada

Jasper.

Cold arctic air entrenched in area yet temperature inversion forming. -22 in valley and -8 at 1900m.

Summary

Weather Forecast

Cold Arctic air remains entrenched for the next few days. No significant precipitation and sunny periods. Winds will feel like they are coming out of the N and E. Inversion setting up as its -22 in the valley and -9 at 1900m.

Snowpack Summary

20cm of snow Thursday's to Sunday in the Icefields area has buried previous wind slabs, tree line and above. The mid-pack remains generally supportive however it appears to be loosing strength particularly in shallow locations. An amazingly good snow pack for the Rockies in December.

Avalanche Summary

Friday's avalanche control work at the Icefields released several loose size 2 avalanches in thin steep snowpack areas below treeline. Natural avalanches have been limited to similar characteristics, steep, rocky, thin areas creating loose avalanches.

Confidence

The weather pattern is stable

Problems

Wind Slabs

Thursday's 10 cm and Sunday's 8cm of snow with little wind has buried the preexisting wind slabs. Winds have shifted from S to N yet remain in light range. Watch for reverse loading patterns from local terrain influences.

The recent snow may now be hiding windslabs that were easily visible before the snow fell.Caution in lee and cross-loaded terrain near ridge crests.

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

Elevations: All elevations.

Likelihood

Unlikely - Possible

Expected Size

1 - 3

Deep Persistent Slabs

The strong mid-pack above this weakness is slowly loosing its strength. Shallow snow pack areas are potential trigger spots. Consequences would be severe if initiated.

Carefully evaluate and use caution around thin snowpack areas.Be aware of thin areas that may propogate to deeper instabilites.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Unlikely

Expected Size

2 - 4

Valid until: Dec 24th, 2012 4:00PM