Avalanche Forecast

Issued: Mar 1st, 2021 4:00PM

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

Avalanche Canada kdevine, Avalanche Canada

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Use caution as you transition into wind exposed terrain, recent fresh snow combined with strong winds have promoted wind slab development. Watch for signs of instability such as whumpfing, cracking and recent avalanches.

Summary

Confidence

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

Weather Forecast

MONDAY NIGHT - Mainly cloudy with a few flurries, up to 5 cm / strong southwest wind / alpine low temperature near -7 

TUESDAY - Mainly cloudy with a few flurries / moderate southwest wind / alpine high temperature near -7 / freezing level 1500 m

WEDNESDAY - A mix of sun and cloud / moderate south wind / alpine high temperature near -4 / freezing level 1700 m

THURSDAY - Mainly sunny / moderate south wind / alpine high temperature near -1 / freezing level 2300 m

Avalanche Summary

Since the storm and associated avalanche cycle eased off early last week, there have been daily reports of size 1-2 natural and human-triggered avalanches in many areas. There have also been reports of larger (size 2-3) explosives triggered avalanches on most days. The size and frequency of these avalanches have generally decreased slightly each day.

There have been a few reports of sporadic persistent slab avalanches failing on the late January persistent weak layer in the past month, including one in the past week. 

Snowpack Summary

There is around 60-100 cm of now sitting on a persistent weak layer of facets that was buried in mid-February. Deep wind deposits and wind slabs exist in the alpine and open treeline areas.

There is now 80-120 cm of snow above the late January persistent weak layer which is composed of surface hoar in sheltered areas in the trees and/ or a crust on steep solar aspects. Very isolated activity on this layer has been observed in the past few weeks.

Terrain and Travel

  • Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
  • Be aware of highly variable recent wind loading patterns.
  • 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 a persistent slab.

Problems

Wind Slabs

An icon showing Wind Slabs

Recent (and ongoing) southwest winds are likely forming wind slabs at upper elevations. Previous variable winds may mean that wind slabs could be found on all aspects. The most reactive ones are likely to be found on northerly aspects.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 2

Persistent Slabs

An icon showing Persistent Slabs

60-100 cm of snow sits on a persistent weak layer of facets that was buried in mid-February.

Another persistent weak layer buried 80-120 cm deep is composed mainly of surface hoar. We are still seeing isolated activity on this layer. 

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible

Expected Size

2 - 3.5

Valid until: Mar 2nd, 2021 4:00PM

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