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Avalanche Forecast

Archived

Feb 9th, 2023–Feb 10th, 2023

Alpine
Natural avalanches possible, human triggered probable.
Treeline
Natural avalanches unlikely, human triggered possible.
Below Treeline
Natural avalanches unlikely, human triggered possible.
Alpine
Natural avalanches possible, human triggered probable.
Treeline
Natural avalanches unlikely, human triggered possible.
Below Treeline
Natural avalanches unlikely.
Alpine
Natural avalanches unlikely, human triggered possible.
Treeline
Natural avalanches unlikely, human triggered possible.
Below Treeline
Natural avalanches unlikely.

Regions

Waterton Lakes, Waterton.

The natural avalanche cycle is tapering after receiving 30 cm of new snow followed by extreme SW winds this week. We expect the sensitivity of the windslab problem to improve through the weekend, trending from likely to possible for human triggering.

Confidence

Low

Avalanche Summary

Field staff did an avalanche patrol on Thursday and found several size 1.5 windslabs had released on lee loaded North through East aspects in the alpine. Last week, a skier on Forum Ridge reported triggering a size 1.5 slab with no involvement which apparently ran on the mid-January crust. This layer remains a concern with the recent new load.

Snowpack Summary

30 cm of storm snow from Tuesday night with extreme winds on Thursday has created fresh windslabs at treeline and above or on steeper exposed slopes below treeline. This brings the treeline snow depth to 50 cm overlying the thick January melt freeze crust that exists up to 2400 m. We are starting to see weak crystals develop above the crust and are monitoring this interface of concern.

Weather Summary

Extreme SW winds should ease Friday evening to more moderate values for Saturday before cranking up again for Sunday as the next system moves into the area. For Friday & Saturday, alpine temperatures will be in the -2 to -13C range. On Sunday freezing levels climb to 2000 m with the passage of a warm front where light rain may occur at lower elevations.

Terrain and Travel Advice

  • Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.

Problems

Wind Slabs

Wind Slab avalanches are the release of a cohesive layer of snow (a slab) formed by the wind. Wind typically transports snow from the upwind sides of terrain features and deposits snow on the downwind side. Wind slabs are often smooth and rounded and sometimes sound hollow, and can range from soft to hard. Wind slabs that form over a persistent weak layer (surface hoar, depth hoar, or near-surface facets) may be termed Persistent Slabs or may develop into Persistent Slabs.