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Avalanche Forecast

Archived

Feb 24th, 2022–Feb 25th, 2022

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

Regions

North Rockies.

Wind slabs will remain reactive to human triggering on all aspects. Use caution in wind-affected terrain, especially on steep, convex slopes or roll-overs.

Confidence

High - Confidence is due to a stable weather pattern with little change expected.

Weather Forecast

A strong ridge of high pressure will keep the region dry and cold until Friday. Wind and snowfalls are expected for the weekend as a shift in the weather pattern will occur.

Thursday night: Partially cloudy. Alpine temperatures around -15 C. Light to moderate northwesterly winds.

Friday: Partially cloudy. Freezing level rising to 500 m. Alpine temperatures around -8 C. Light to moderate westerly winds.

Saturday: Cloudy with light snowfall. Freezing level rising to 1200 m. Alpine temperatures around -6 C. Strong to extreme southwesterly winds.

Sunday: Snow 10-15 cm. Freezing level rising to 1200 m. Alpine temperatures around -4 C. Strong to extreme southerly winds.

Avalanche Summary

Thursday, snowmobilers were able to easily trigger soft wind slabs (size 1) on rollovers in open trees. Wednesday, a loose dry avalanche ran especially far after being skier-triggered on a steep convexity.

Earlier this week, shifting winds have redistributed the storm snow into wind slabs and several natural avalanches occurred. Check out our field team's MIN report from Pine Pass earlier this week.

During the peak of the storm last Saturday, several large natural storm slab avalanches were reported from treeline elevations around Kakwa. 

Snowpack Summary

Last weekend's storm brought 20-100 cm of new snow. Recent northeasterly winds have been redistributing this new snow into wind slabs in lee areas and creating a heavily wind-affected surface in the alpine and exposed treeline. This new snow overlies a widespread crust created from a rain event in early February. This 1-20 cm thick crust exists on all aspects and elevations. 

Below the crust, 10-40 cm of more settled snow exists above the late January weak layer. This layer consists of weak faceted snow, a melt-freeze crust, and surface hoar crystals in isolated sheltered areas at treeline and below. In most areas, this layer is bridged by the thick crust above it. It is currently considered dormant, but could become active later this season. 

The lower snowpack is generally strong and well-bonded. The base of the snowpack is expected to be weak and faceted in shallow, rocky slopes east of the divide.

Terrain and Travel

  • Recent wind has varied in direction so watch for wind slabs on all aspects.
  • Closely monitor how the new snow is bonding to the crust.
  • Look for signs of instability: whumphing, hollow sounds, shooting cracks, and recent avalanches.

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.