Avalanche Forecast

Issued: Feb 21st, 2021 3:00PM

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

Avalanche Canada JMackenzie, Avalanche Canada

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20cm of new snow coupled with extreme SW winds on Sunday night and Monday morning will push the hazard levels to HIGH. Avoid avalanche terrain.

Summary

Confidence

Moderate -

Weather Forecast

It's windy! Sunday evening will see wind speeds reaching 150km/h at ridgetop out of the SW and there is a wind warning in effect. By Monday morning the winds will slow down to 100km/h, and further decrease to 50km/h by the afternoon. Even for K-country this is extreme winds. Temperatures on Monday should climb to -5 by midday, and as much as 20cm of new snow is expected at Treeline elevations, with possibly rain in the Bow Valley.

Avalanche Summary

No new avalanche activity was observed Sunday, but visibility was limited.

Snowpack Summary

Extreme winds on Sunday are stripping all the remaining snow from windward aspects and depositing that snow into lee and cross-loaded features. Wind slabs are widespread at Treeline and above, and can even be found in open areas at lower elevations. The depths of the wind slabs are highly variable (5 to 80cm), as is the sensitivity to triggering. In exposed Alpine areas expect hard, dense wind slab conditions, but as you loose elevation these slabs are softer and potentially more triggerable. Be mindful of rapidly changing conditions as you travel through the terrain.

Terrain and Travel

  • Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
  • Be careful with wind slabs, especially in steep, unsupported and/or convex terrain features.
  • Watch for areas of hard wind slab on alpine features.
  • Avoid lee and cross-loaded terrain.

Problems

Wind Slabs

An icon showing Wind Slabs

Extreme winds have created new slabs at treeline and alpine elevations. With the incoming snow and continued extreme winds on Monday, these slabs will get deeper and more widespread.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Very Likely

Expected Size

1 - 3

Persistent Slabs

An icon showing Persistent Slabs

Wind slabs in the upper snowpack may step down to the Jan 29th interface down 50-100cm. Dig down and evaluate this interface as you travel. 

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

2 - 3

Valid until: Feb 22nd, 2021 3:00PM