Avalanche Canada shorton, Avalanche Canada

Cariboos Avalanche Forecast

Jan 12th, 2020 5:00PM

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

A buried weak layer has potential to produce large avalanches around treeline elevations, warranting extra caution around steep open slopes.

Summary

Confidence

Moderate - Uncertainty is due to how quickly the snowpack will recover and gain strength.

Weather Forecast

SUNDAY NIGHT: Clearing overnight, light wind from the north, alpine temperatures drop to -35 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.

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

Avalanche Summary

There have been limited field observation recently, but enough to suggest the persistent slab avalanche problem remains a serious concern. A large persistent slab avalanche was triggered by a rider in the neighbouring Clemina area on Friday in upper treeline terrain (see the MIN report) and riders on Belle Mountain near McBride reported "thunderous" whumpfing in south facing terrain at treeline. Over the past week there have been several reports of avalanches releasing on this problematic surface hoar layer (check out this MIN, this MIN, and this MIN for helpful illustrations). 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.
  • Avoid freshly wind loaded features, especially near ridge crests, roll-overs and in steep terrain.
  • Choose slopes that are well supported and have limited consequence.

Problems

Persistent Slabs

An icon showing Persistent Slabs

Likelihood

Possible-Likely

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 terrain decisions.

Aspects:

All aspects.

Elevations:

Treeline, Below Treeline.

Wind Slabs

An icon showing Wind Slabs

Likelihood

Likely

Expected Size

1 - 2

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

Aspects:

All aspects.

Elevations:

Alpine, Treeline.

Valid until: Jan 13th, 2020 5:00PM