Avalanche Forecast

Issued: Nov 20th, 2015 4:08PM

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

Parks Canada snow safety, Parks Canada

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Banff Yoho Kootenay.

Watch for wind slabs in exposed terrain on high alpine slopes, especially where they may overly facets. Two storms have formed most of the current snowpack, and it is a very supportive snowpack considering it is only November. Great ski conditions!

Summary

Weather Forecast

Alpine temperatures will stay in the -10 to -20C range for Saturday with mainly light W winds. Temperatures will warm up overnight on Saturday but still stay below freezing. Winds will increase Sunday as we switch to more of a westerly flow with light precipitation expected throughout the day.

Snowpack Summary

A field trip in the Lake Louise area today found 80-100cm of supportive snow at treeline. Above treeline there was extensive wind slab development. The wind slabs were not reactive to skier triggering today but are still a concern, especially in thin snow pack areas. This is consistent with other observations. Overall a good early season snowpack.

Avalanche Summary

A couple small wind triggered slides in steep alpine terrain today. Only minor results from explosive testing during the last two days. Avalanche control Wednesday produced wind slab failures up to size 2.5, one size 3 was triggered on Mt. Stephen at 3000m which appeared to initiate near the ground.

Confidence

Due to the number and quality of field observations

Problems

Wind Slabs

An icon showing Wind Slabs
In thicker snowpack areas wind slabs have formed over previous storm snow and are less sensitive to triggering. In thinner snowpack areas these may be lying over weaker basal facets formed in late fall, and be more sensitive to skier triggering.
Use caution in lee areas. Recent wind loading has created wind slabs.

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

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

1 - 3

Valid until: Nov 21st, 2015 4:00PM

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