Avalanche Forecast

Issued: Feb 5th, 2021 4:00PM

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

Avalanche Canada ahanna, Avalanche Canada

Email

Reactive wind slabs may exist at upper elevations. The persistent weak layer may still be possible to trigger in areas around treeline that have not already avalanched.

Summary

Confidence

Moderate - Uncertainty is due to limitations in the field data.

Weather Forecast

Friday night: Mostly cloudy, moderate northwest ridgetop wind, treeline temperature -1, freezing level 1000 m.

Saturday: Light flurries, up to 5 cm, strong northwest ridgetop wind, treeline high -1, freezing level 1000 m. 

Sunday: Mix of sun and cloud, light westerly ridgetop wind, treeline high -5, freezing level 500 m. 

Monday: Mix of sun and cloud, light northwest ridgetop wind, treeline high -7, freezing level 300 m. 

Avalanche Summary

Human triggered storm slab avalanches remain likely in wind loaded areas at upper elevations. The recently buried persistent weak layer may be possible to trigger in areas that have not already avalanched.

It was a busy week for avalanche activity in the South Coast mountains, with natural and/or human triggered avalanches reported every day between Monday, January 25, and Monday, February 1, culminating in a widespread natural avalanche cycle, with avalanches up to size 3, on Monday night. Most of these avalanches failed on the persistent weak layer. This was likely the peak of the avalanche activity associated with this layer. 

North Shore Rescue responded to a serious, but non-fatal avalanche incident last Tuesday evening near Cypress Mountain Resort. One person was involved and was partially buried. The avalanche was a size 2 storm slab on a west aspect at approximately 1100 m and failed on the persistent weak layer.

Snowpack Summary

100-150 cm of snow sits over a widespread persistent weak layer. This weak layer consists of a crust that also has weak facets and surface hoar on top of it in many areas. Although very much still present, low elevationsrain crusts and dense snow closer to the surface have a bridging effect over this layer, making it more difficult to trigger.

Click here to watch North Shore Rescue's snowpack conditions update from Friday.

Terrain and Travel

  • Be careful as you transition into wind affected terrain.
  • Conditions may have improved, but be mindful that deep instabilities are still present.

Problems

Wind Slabs

An icon showing Wind Slabs

Wind slabs may remain triggerable by humans. Be aware of the potential for wind loading in atypical terrain features on southerly aspects due to recent northerly winds.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

1 - 2

Persistent Slabs

An icon showing Persistent Slabs

A widespread weak layer consisting of a crust, with facets and/or surface hoar overtop is now down about 100-150 cm. This layer may still produce large avalanches in areas that have not already avalanched.

Aspects: All aspects.

Elevations: Treeline.

Likelihood

Unlikely

Expected Size

2 - 3

Valid until: Feb 6th, 2021 4:00PM