Avalanche Canada mconlan, Avalanche Canada

Cariboos Avalanche Forecast

Jan 17th, 2020 4:00PM

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

Variable wind directions and a blanket of new snow mean that wind slabs could be triggered in exposed terrain.

Summary

Confidence

Moderate - Uncertainty is due to limitations in the field data.

Weather Forecast

FRIDAY NIGHT: Increasing clouds, light southwest wind, alpine temperature -18 C, freezing level below valley bottom.

SATURDAY: Cloudy with snowfall, accumulation 5 to 10 cm, moderate to strong southwest wind, alpine temperature -12 C, freezing level below valley bottom.

SUNDAY: Cloudy with light snowfall, accumulation 2 to 5 cm, moderate to strong southwest wind, alpine temperature -7 C, freezing level below valley bottom.

MONDAY: Cloudy with snowfall, accumulation 5 to 10 cm, moderate to strong southwest wind, alpine temperature -5 C, freezing level 1200 m.

Avalanche Summary

Avalanche activity has quieted down over the past few days, but light snowfall and southwest switching to northeast wind are likely refreshing the wind slab problem. A rise in air temperature in the coming days may increase slab properties in the recent snow.

Last weekend there were notable signs of a reactive persistent slab problem, including large whumpfs and a large snowmobile triggered avalanche in the neighbouring Clemina area (see the MIN report). The surface hoar layer responsible for this problem has been harder to find since then, but could still potentially produce large avalanches in certain sheltered slopes around treeline. The likelihood of triggering this layer could increase as the air temperature rises.

Snowpack Summary

Surface conditions are variable due to the recent cold temperature and variable wind directions. Fresh wind slabs are likely present on exposed slopes at and above treeline.

The main concern over the past week has been a layer of surface hoar buried 60-120 cm beneath the surface. Although an avalanche has not been reported on this layer in the past four days, the likelihood of triggering it may increase as new snowfall accumulates and stresses it.

Terrain and Travel

  • Be careful with wind loaded pockets, especially near ridge crests and roll-overs.
  • Be aware of highly variable recent wind loading patterns.
  • Approach steep open slopes at and below treeline cautiously, buried surface hoar may exist.

Problems

Wind Slabs

An icon showing Wind Slabs

Likelihood

Possible-Likely

Expected Size

1 - 2

A switch of the wind direction from northeast to southwest means that wind slabs may be found on all aspects. Triggering wind slab avalanches is possible in exposed terrain at higher elevations, especially near ridges.

Aspects:

All aspects.

Elevations:

Alpine, Treeline.

Persistent Slabs

An icon showing Persistent Slabs

Likelihood

Unlikely-Possible

Expected Size

2 - 3

A layer of surface hoar buried 60-120 cm below the surface could still be reactive to human triggering in clearings around treeline.

Aspects:

All aspects.

Elevations:

Treeline, Below Treeline.

Valid until: Jan 18th, 2020 5:00PM