Avalanche Forecast

Issued: Dec 28th, 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 Deep Persistent Slabs.

A.L. Horton, Parks Canada

Jasper.

Continued loose snow avalanches on steep alpine and tree line slopes. Be prepared for these sloughing on or under slopes and ice climbs .

Summary

Weather Forecast

Light NW winds with the possibility of some light snow flurries can be expected on Saturday. Cool overnight temperatures will warm to above seasonal values by the afternoon with sunny breaks.

Snowpack Summary

Moderate to strong SW winds have created 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

In the past 2 days, 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 on Saturday

Problems

Wind Slabs

Moderate to strong westerly winds have created wind slab conditions on slopes and along ridge lines especially in the Icefields area. No avalanche activity has been observed on this condition, however, we have not tested the bonding strength.

Avoid freshly wind loaded features.

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

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

1 - 3

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.

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

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible

Expected Size

1 - 3

Valid until: Dec 29th, 2012 4:00PM