Avalanche Forecast

Issued: Mar 6th, 2020 4:00PM

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

Avalanche Canada JMackenzie, Avalanche Canada

Avoid avalanche terrain. An avalanche cycle is ongoing.

Summary

Confidence

High -

Weather Forecast

Heavy snow is expected on Saturday with as much as 30cm possible by the end of day. Temperatures will fall with the approaching cold front with midday temps near -10. Winds will also decrease slightly with light to moderate SW winds.The storm ends late Saturday bringing a mix of sun and cloud on Sunday.

Avalanche Summary

Ski cutting produces loose dry avalanches up to size 1.0 in steep Treeline terrain. Some small slabs were also triggered in this elevation band on small, non-consequential test features. Visibility was extremely limited in heavy snow all day, but we suspect there is a natural avalanche cycle ongoing.

Snowpack Summary

Heavy snow today and last night has deposited up to 15cm of fresh snow in the past 24 to 36 hours. The recent storm snow is settling and now consists of 40 to 60cm in the past week. The new snow does not appear to be bonding well and is sluffing easily in steeper terrain with ski cutting. In the Alpine and open areas at Treeline there are widespread wind slabs of varying depths and densities. The forecast team today observed cracking and small releases while ski testing in small steep convex features at 2300m.

Terrain and Travel

  • Avoid freshly wind loaded terrain features.
  • Be aware of the potential for large avalanches due to the presence of a deep persistent slab.
  • Avoid lee and cross-loaded terrain.
  • Be cautious of sluffing.
  • Extra caution is needed around cornices under the current conditions.
  • Choose simple, low-angle, well supported terrain without convexities.
  • Make conservative terrain choices and avoid overhead hazard.

Problems

Wind Slabs

An icon showing Wind Slabs

Wind slabs are everywhere at Treeline and above. These slabs are sensitive to human triggering, and a natural avalanche cycle is occurring. 

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Very Likely - Almost Certain

Expected Size

1.5 - 2.5

Cornices

An icon showing Cornices

Cornices are large and easily triggered. A large cornice failure could trigger a wind slab or a deep persistent slab on the underlying slope. Avoid all exposure to cornices.

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

Elevations: Alpine, Treeline.

Likelihood

Very Likely

Expected Size

1.5 - 3

Deep Persistent Slabs

An icon showing Deep Persistent Slabs

This problem is still with us. Thin snowpack areas are generally more concerning, as this is where triggering the deep instability is more likely.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

2 - 3.5

Valid until: Mar 7th, 2020 4:00PM

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