Avalanche Forecast

Issued: Dec 10th, 2012 4:00PM

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

steve blake, Parks Canada

Jasper.

Summary

Weather Forecast

Continued moderate temperatures with light winds and little new snow is in the forecast.

Snowpack Summary

A wind event on Sunday brought moderate to strong NW winds. These winds moved a significant amount of snow and created a stiff surface slab condition. Expect variable wind loading patterns as directions vary with local terrain influences.

Avalanche Summary

Saturday three size 2-2.5 avalanches were noted now 48-72 hours old, 40 degree plus, NW aspect, cross loaded gullys. Explosive work on parkers slabs on Thursday with 22 avalauncher rounds produced one size 2 slab avalanche in a windloaded location on smooth steep rock slab. Expect current winds to increase potential for natural avalanche activity.

Confidence

Due to the number and quality of field observations

Problems

Wind Slabs

Sunday's winds created a stiff wind slabs on lee aspects particularly at high elevation ridge tops and specific features such as alpine gullies. Watch for reverse loading patterns and increasing natural activity.

Be careful with wind loaded pockets while approaching and climbing ice routes.Avoid lee and cross-loaded terrain near ridge crests.

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

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

2 - 3

Persistent Slabs

A persistent facetted weakness can be found around a mid-pack crust.

Avoid unsupported slopes.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

2 - 3

Deep Persistent Slabs

This layer continues to develop in shallow snowpack areas which would be your likely trigger spots. Has potential to step down to ground if initiated.

Be aware of thin areas that may propogate to deeper instabilites.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

1 - 3

Valid until: Dec 11th, 2012 4:00PM