Avalanche Forecast

Issued: Nov 29th, 2020 4:00PM

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

Avalanche Canada JSmith, Avalanche Canada

Lingering wind slabs may remain surprisingly reactive to human triggers in areas where they are sitting on top of a layer of small surface hoar.

Summary

Confidence

Low - Uncertainty is due to the limited number of field observations.

Weather Forecast

 SUNDAY NIGHT: Mostly cloudy / Light, southwest wind / alpine low temperature -15 / Freezing level valley bottom.

 MONDAY: Snow, 5-10 cm / Light, west wind / alpine high temperature -8 / Freezing level valley bottom.

TUESDAY: Sunny / Light, west wind / alpine high temperature -7 / Freezing level valley bottom.

WEDNESDAY: Sunny / Light, south wind / alpine high temperature +1 / Strong inversion with an above freezing layer of air above 2000 m.

Avalanche Summary

Check out this notable MIN report of numerous human triggered avalanches from Quartz Creek on Saturday. The recently buried layer of small surface hoar that caused this avalanche could likely catch riders by surprise.

Data is very sparse in this region. Please submit your observations to the Mountain Information Network.

Snowpack Summary

  Recent strong southwest winds have created fresh wind slabs on lee features at treeline and above. There have been a couple human triggered avalanches on a recently buried layer of small surface hoar. This layer has been reported as "spotty" and is most likely to be present in sheltered areas. There is a crust from early November that is down approximately 50-75 cm. This layer has been observed to have weak, sugary facets above and below it and is most likely to be reactive to human triggers on south facing slopes and in shallow, rocky, snowpack areas in the alpine.

Terrain and Travel

  • Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
  • If triggered, wind slabs avalanches may step down to deeper layers resulting in larger avalanches.
  • In times of uncertainty conservative terrain choices are our best defense.
  • Closely monitor how the new snow is bonding to the old surface.
  • Carefully assess open slopes and convex rolls where buried surface hoar may be preserved.

Problems

Wind Slabs

An icon showing Wind Slabs

Lingering wind slabs may remain surprisingly reactive to human triggers in areas where they are sitting on top of a layer of small surface hoar.

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

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 2

Deep Persistent Slabs

An icon showing Deep Persistent Slabs

A crust from early November exists down about 50-75 cm. This layer has weak, sugary facets above and below it. This layer is most likely to be reactive to human triggers on south facing slopes and in shallow, rocky, snowpack areas in the alpine.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1.5 - 2.5

Valid until: Nov 30th, 2020 4:00PM