Avalanche Forecast

Issued: Jan 18th, 2018 4:00PM

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

william lawson, Parks Canada

Banff Yoho Kootenay.

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

Summary

Weather Forecast

Snow tapering Thursday with only trace amounts expected by Friday. 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 facet/ surface hoar/ sun crust layer is still a concern in the forecast region, in many areas this layer now sits 40-60 cm down. Much of the snowpack is well facetted with little structure below treeline.

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 accompanying winds have created windslabs 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 continues to be the cause of much uncertainty with forecasters - we think its bad, but yet it has not yet produced many large avalanches. We remain uneasy about it despite indications of generally good conditions.

Watch for whumpfing, hollow sounds, shooting cracks or recent avalanches.Choose conservative lines and watch for clues of instability.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 2.5

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