Avalanche Forecast

Issued: Jan 6th, 2021 4:00PM

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

Avalanche Canada ghelgeson, Avalanche Canada

Email

Skies are clearing after the storm and it's tempting to get into the big terrain, but this snowpack remains spooky. It's capable of producing very large human triggered avalanches and I don't trust it. The best and safest riding will be found in mellow wind sheltered terrain.

Summary

Confidence

Low - Uncertainty is due to the limited number of field observations. Uncertainty is due to extremely variable snowpack conditions reported through the region.

Weather Forecast

Clearing skies and continued southwest wind expected for the forecast period.

WEDNESDAY NIGHT: Freezing level at valley bottom, moderate to strong southwest wind, trace of snow possible.

THURSDAY: A few clouds, freezing level at valley bottom, moderate to strong southwest wind, no significant snowfall expected.

FRIDAY: Scattered cloud cover, freezing level at valley bottom, moderate to strong southwest wind, no snow expected.

SATURDAY: Scattered cloud cover, freezing level at valley bottom, moderate southwest wind, no snow expected.

Avalanche Summary

Recent reported avalanche activity is scarce. If you see something, please snap a photo of it and submit it to the Mountain Information Network, thanks!

Check out this MIN report from the North Rockies field team on Sunday that gives an indication of natural avalanche activity that resulted from the weekend storm in the Renshaw area.

Snowpack Summary

The region received up to 55 cm from the weekend storm, with the deepest amounts being found to the north. Up to 120 cm of settling storm snow can be found in the deeper drifts, this snow has all fallen in the New Year. The weekend storm was pretty warm, and you're likely to find a crust on the surface up to about 1100 m.

At this point 40 to 120 cm of snow is now sitting above a mix of weak interfaces that were buried in early December. This MIN provides a good illustration of that from one of the thinner snowpack areas in the region. Depending on location, the buried weak layer of concern is composed of weak surface hoar or weak crusts and facet layers which has created a persistent slab avalanche problem.

We do not see a clear pattern in which parts of the region or which types of terrain this problem is still a concern. 

Between Dec 18-20 there was compelling evidence of this problem around Pine Pass, the McGregors, and Tumbler Ridge. This problem has not been found at Renshaw, but has been found in the surrounding areas near McBride. There is no recent information from Kakwa. 

Overall, uncertainty about these layers make it difficult to have confidence in challenging or complex avalanche terrain without very careful terrain evaluation and an in-depth understanding of local snowpack conditions. We're firmly in a low probability high consequence scenario now.

Snow depths are 150-250 cm around Pine Pass, the McGregors, and McBride and closer to 100-150 cm around Tumbler Ridge. In shallower areas along the eastern slopes there is likely weak snow at the bottom of the snowpack that could be a concern in steep rocky alpine terrain.

Terrain and Travel

  • Avoid steep, rocky, and wind effected areas where triggering slabs is more likely.
  • Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
  • Be aware of the potential for large avalanches due to the presence of buried persistent weak layers.

Problems

Wind Slabs

An icon showing Wind Slabs

As last weekend's storm snow gradually settles and bonds to the old surface, wind loaded areas remain suspect. Recent reports suggest wind has been redistributing snow even in lower elevation openings in forested areas and more strong winds are in the forecast.

Aspects: North, North East, East, West, North West.

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 2

Persistent Slabs

An icon showing Persistent Slabs

A persistent weak layer exists throughout the region 50-120 cm below the surface. The catch is that this layer is present on some slopes, and then absent on nearby slopes. Over the past week or so this problem has evolved into a 'low probability/high consequence' scenario that demands careful terrain selection and diligent travel practices.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible

Expected Size

2 - 3

Valid until: Jan 8th, 2021 4:00PM