Avalanche Canada shorton, Avalanche Canada

Cariboos Avalanche Forecast

Jan 10th, 2020 5:00PM

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

Questions remain about which slopes have the potential to produce large persistent slab avalanches. Cautious route-finding and conservative terrain choices are recommended.

Summary

Confidence

Moderate - Uncertainty is due to the speed, direction, or duration of the wind and its effect on the snowpack.

Weather Forecast

FRIDAY NIGHT: Cloudy, light wind from the southwest, alpine temperatures drop to -16 C.

SATURDAY: Cloudy, 5-15 cm of snow, light wind from the west, alpine high temperatures around -15 C.

SUNDAY: Mix of sun and cloud, light wind from the north, alpine high temperatures around -20 C.

MONDAY: Mostly sunny, light wind from the north, alpine high temperatures around -25 C.

Avalanche Summary

Large avalanches (size 2-3) were observed in the wake of Tuesday and Wednesday's storm. Many of these avalanches released on a surface hoar layer that formed in late December resulting in 60-120 cm thick slabs. Check out this MIN, this MIN, and this MIN for helpful illustrations of slopes that are likely to harbor this problem. Looking forward, this problem appears to have variable distribution across the region, meaning steep terrain should continue to be approached cautiously.

Snowpack Summary

Low density snow continues to accumulate. Most areas likely have 10-30 cm of soft snow, but stiffer and reactive slabs could be forming in terrain affected by the wind. Recent storms have loaded a concerning layer of surface hoar from late December, which is now buried 60-120 cm deep. Recent observations and snowpack tests suggest the reactivity of this layer is now variable across the region. Preserved surface hoar could potentially be found on sheltered slopes anywhere in the region, with the potential for producing large avalanches.

Terrain and Travel

  • Approach steep open slopes at and below treeline cautiously, buried surface hoar may exist.
  • Be especially cautious as you transition into wind affected terrain.
  • If triggered, wind slabs avalanches may step down to deeper layers resulting in larger avalanches.

Problems

Persistent Slabs

An icon showing Persistent Slabs

Likelihood

Possible

Expected Size

2 - 3.5

A concerning layer of surface hoar from late December is now buried 60-120 cm deep. This layer has produced many large avalanches, sometimes pulling back into low angle terrain. This problem warrants conservative margins with terrain decisions.

Aspects:

All aspects.

Elevations:

All elevations.

Wind Slabs

An icon showing Wind Slabs

Likelihood

Possible-Likely

Expected Size

1 - 2

Low density snow may be blown into unstable slabs on lee features at and above treeline, especially near ridgetops.

Aspects:

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

Elevations:

Alpine, Treeline.

Valid until: Jan 11th, 2020 5:00PM