Avalanche Forecast

Issued: Jan 4th, 2021 4:00PM

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

Avalanche Canada kdevine, Avalanche Canada

Storm slabs are likely still reactive to human triggering, especially in wind loaded areas. Watch for signs of instability such as whumpfing, cracking, and recent avalanches.

Concern remains for persistent weak layers, which are best managed through conservative terrain choices.

Summary

Confidence

Moderate - Uncertainty is due to the fact that persistent slabs are particularly difficult to forecast.

Weather Forecast

MONDAY NIGHT - Cloudy with clear periods and isolated flurries, up to 5 cm / light to moderate west wind / alpine low temperature near -10

TUESDAY - A mix of sun and cloud with a few flurries / light southwest wind becoming moderate south in the afternoon / alpine high temperature near -7 

WEDNESDAY - Mainly cloudy with a few flurries, around 5 cm / moderate southwest wind, easing in the afternoon / alpine high temperature near -5 / freezing level 1300 m

THURSDAY - A mix of sun and cloud / light northeast wind / alpine high temperature near -6

Avalanche Summary

At the time of publishing, there were a few reports of natural size 2.5 wind slab avalanches on north and east-facing terrain in the alpine on Monday.

On Sunday there were reports of numerous natural, human and explosives triggered avalanches up to size 2. There was also one natural size 2.5 deep persistent slab avalanche reported on a north aspect at 2500 m near Invermere. 

NOTABLE MIN from Sunday Here.

On Thursday, a ski cut resulted in a size 2 persistent slab avalanche on a northeast aspect in the alpine near Kicking Horse Mountain Resort. MIN report HERE.

A skier triggered avalanche was reported in the Golden area on Wednesday. Check out the MIN report HERE

These recent avalanches are a reminder that when persistent slabs are the problem; conservative terrain choices are the answer.

Snowpack Summary

25-35 cm of recent snow with previous strong southwest winds have formed storm slabs at all elevations.

There are currently several layers of concern in much of the region's snowpack. 40-50 cm of snow sits on yet another weak layer of surface hoar that was reported in the Golden area. 

The mid-December surface hoar is now down 90-130 cm. Although there have been no new reports of avalanches on this layer in the last few days, it remains possible to trigger where it is well preserved. There may also be a crust near, or instead of this layer in some areas.

The lower snowpack is characterized by more crusts, the most notable is a rain crust from early November that is sitting near the base of the snowpack, surrounded by a weak layer of sugary facets. It is most likely to be reactive to human triggers in steep, shallow, rocky areas with a thin to thick snowpack.

Terrain and Travel

  • Uncertainty is best managed through conservative terrain choices at this time.
  • If triggered, wind slabs avalanches may step down to deeper layers resulting in larger avalanches.
  • Be aware of the potential for large avalanches due to the presence of buried persistent weak layers.
  • Remote triggering is a concern, watch out for adjacent and overhead slopes.
  • Avoid shallow, rocky areas where the snowpack transitions from thick to thin.

Problems

Storm Slabs

An icon showing Storm Slabs

Storm slabs in motion may step down to deeper weak layers, resulting in large avalanches.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible - Likely

Expected Size

1.5 - 2.5

Persistent Slabs

An icon showing Persistent Slabs

A weak layer of surface hoar down 50-100 cm has been reactive to human triggers, resulting in large avalanches.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible - Likely

Expected Size

2 - 3

Deep Persistent Slabs

An icon showing Deep Persistent Slabs

A crust buried near the bottom of the snowpack has been responsible for some very large explosive triggered avalanches up to size 4.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

2.5 - 4

Valid until: Jan 5th, 2021 4:00PM