Avalanche Canada shorton, Avalanche Canada

Cariboos Avalanche Forecast

Jan 11th, 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 fact that persistent slabs are particularly difficult to forecast.

Weather Forecast

SATURDAY NIGHT: Mostly cloudy, light to moderate wind from the northwest, alpine temperatures drop to -25 C.

SUNDAY: Mix of sun and cloud with isolated flurries and trace accumulations of snow, 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.

TUESDAY: Sunny, light wind from the north, alpine high temperatures around -28 C.

Avalanche Summary

No new avalanches have been reported over the past three days. A large persistent slab avalanche was triggered by a rider in the Clemina area on Friday (see the MIN report). Although this is in the neighboring North Columbia region, a similar problem exists in the Cariboos. Over the past week avalanches releasing on the same surface hoar layer have been reported in the Cariboos. 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

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. Now questions remain about which slopes could still harbour this problem, which warrants conservative margins with terrain decisions.

Aspects:

All aspects.

Elevations:

All elevations.

Wind Slabs

An icon showing Wind Slabs

Likelihood

Possible

Expected Size

1 - 2

Monitor changes in the most recent low density snow. It may be blown into unstable slabs in wind affected terrain or run as small dry loose avalanches in steep terrain.

Aspects:

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

Elevations:

Alpine, Treeline.

Valid until: Jan 12th, 2020 5:00PM