Avalanche Forecast

Issued: Jan 18th, 2018 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.

william lawson, Parks Canada

Little Yoho.

New windslab formation has created a reactive avalanche problem at higher elevations.

Summary

Weather Forecast

Storm ending Thursday evening with another smaller pulse expected Saturday bringing in 5-10cm. Temperatures are expected to cool into the weekend with daytime highs of -5. Winds will drop Monday night and hold steady in the light to moderate range for the weekend.

Snowpack Summary

Moderate to strong winds over the past 24 hours has developed windslabs on immediate lees at alpine and treeline elevations. The Dec 15 surface hoar layer is still a concern in the forecast region, in many areas this layer now sits 50-80 cm down with a well settled slab above. Much of the lower snowpack consist of facets.

Avalanche Summary

One size 2 natural avalanche observed releasing from a wind loaded lee features. Many small size 1 avalanches triggered from ski cut releasing pockets of winds lab at treeline and above. All avalanches observations today were releasing from windslab.

Confidence

Problems

Wind Slabs

New snow and wind are have created new windslabs on lee slopes at alpine and treeline elevations. Due to variable winds in the alpine expect the spacial distribution of this problem to be widespread.

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

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 2

Persistent Slabs

This layer is a concern mainly at treeline around Field, Emerald Lake and Little Yoho - this is a very specific band. Natural avalanches are unlikely but human triggered are likely - watch overhead hazard BTL; avalanches can run into the forest.

Avoid open slopes and convex rolls at treeline where buried surface hoar may be preserved.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 3

Valid until: Jan 19th, 2018 4:00PM