Parks Canada mark herbison, Parks Canada

Little Yoho Avalanche Forecast

Jan 11th, 2020 4:00PM

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 will likely persist for some time. There is great skiing, but now is the time for conservative decision making. Ice climbers be cautious of steep gullies and sluffing between ice pitches.

Summary

Weather Forecast

Mainly cloudy with isolated flurries of low density, fluffy snow. The temps will begin to drop and will range from -12 to -26, as the winds will shift Sunday morning and be light from the East. It will remain cold and mainly sunny until at least late next week.

Snowpack Summary

30-50 cm of snow since Jan 1 sits over a variety of surfaces including facets, surface hoar and sun crust. Stability tests throughout the region show 'sudden' results on this interface. Reactive wind slabs exist in alpine and some tree line locations. In most areas there is a well settled mid-pack over top of a weaker basal layer.

Avalanche Summary

Parks Canada responded to a size 2.5 skier triggered avalanche on the South flanks of Mt. Hector yesterday. Its suspected that the initially triggered wind slab stepped down to deeper layers.

Several naturals sz 2-3 were observed Thursday throughout the forecast region, some of which failed at the ground within the deep persistent layer.

Confidence

Problems

Persistent Slabs

An icon showing Persistent Slabs

Likelihood

Likely - Possible

Expected Size

1 - 2.5

This layer consists of surface hoar / facets / sun crust and is down 40-60 cm throughout the region and is producing 'sudden' results in stability tests. Several skier triggered avalanches have occurred recently on this layer.

  • Carefully evaluate terrain features by digging and testing on adjacent, safe slopes.
  • If triggered the persistent slab may step down to deeper layers resulting in large avalanches.

Aspects:

All aspects.

Elevations:

Treeline, Below Treeline.

Wind Slabs

An icon showing Wind Slabs

Likelihood

Likely - Possible

Expected Size

1 - 2

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

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

Aspects:

North, North East, East, South East, North West.

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 the past few days. Click on Forecast Details tab for more information.

  • Avoid shallow snowpack areas where triggering is more likely.
  • Pay attention to overhead hazards like cornices which could trigger the deep persistent slab.

Aspects:

All aspects.

Elevations:

All elevations.

Valid until: Jan 12th, 2020 4:00PM