Parks Canada Brian Webster, Parks Canada

Banff Yoho & Kootenay National Park Avalanche Forecast

Jan 9th, 2020 4:50PM

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

Problems within the snowpack are complex and likely will persist for some time. There is great skiing, but now is the time for conservative decision making.

Summary

Weather Forecast

A frontal system from BC will push into Alberta on Friday bringing light snow along the Divide (5-10 cm).  Temperatures will remain cool with day time highs only rising to -11 in Lake Louise. On Sunday a ridge of cold arctic air will descend bringing a significantly colder air mass to the area.

Snowpack Summary

30-50 cm of storm snow since Jan 1 sits over a variety of surfaces including facets and surface hoar. Field tests throughout the region show easy to moderate results on this interface. Reactive wind slabs exist in alpine and some treeline locations. In most areas there is a well settled mid-pack over top of a weaker basal layer.

Avalanche Summary

Field trip to Bow Summit showed evidence of a wide-spread cycle up to size 3 on all aspects tree-line and above from past 48-72 hours. A size 3 natural on Thursday was observed on the east face of Bow Peak. There were also reports of large naturals in the Sunshine area (above Bourgeau Right ice climb) and on Mt Rundle.

Confidence

Problems

Persistent Slabs

An icon showing Persistent Slabs

Likelihood

Likely - Possible

Expected Size

1.5 - 2.5

This layer exists down 40-60 cm throughout the region and is producing easy to moderate results with stability tests. Several skier triggered avalanches have occurred recently on this layer.

  • Carefully evaluate terrain features by digging and testing on adjacent, safe slopes.

Aspects:

All aspects.

Elevations:

Treeline.

Wind Slabs

An icon showing Wind Slabs

Likelihood

Likely

Expected Size

1 - 2

Recent storm snow and mod to strong winds have created storm and wind slabs in alpine and treeline elevations. It will take several days for these instabilities to settle out.

  • If triggered the storm slabs may step down to deeper layers resulting in large avalanches.
  • Use caution in lee areas. Recent wind loading have created storm slabs.

Aspects:

All aspects.

Elevations:

Alpine, Treeline.

Deep Persistent Slabs

An icon showing Deep Persistent Slabs

Likelihood

Possible

Expected Size

2 - 3.5

The potential for deeper releases on the basal layers still exist. Several large avalanches have occurred on this layer in past 48 hours. Click on Forecast Details tab for more information.

  • Avoid shallow snowpack areas where triggering is more likely.

Aspects:

All aspects.

Elevations:

All elevations.

Valid until: Jan 10th, 2020 4:00PM