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Avalanche Forecast

Archived

Mar 11th, 2023–Mar 12th, 2023

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

Regions

North Rockies, Kakwa, McGregor, Pine Pass, Tumbler.

Strong northeasterly winds have formed wind slabs on lee aspects at treeline and above.

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

Confidence

Moderate

Avalanche Summary

A couple small (size 1.5) naturally triggered wind slabs on steep west aspects in the alpine were reported on Friday.

A notable very large avalanche triggered by a cornice fall was reported in the pine pass area last weekend. See MIN.

Snowpack Summary

Strong northeast have formed fresh wind slabs on lee aspects at treeline and above.

Thin sun crust can be found a steep, sunny slopes. Soft snow can be found in areas sheltered from wind and sun.

The middle of the snowpack is generally well settled and strong.

A weak layer of large and weak facets is found near the base of the snowpack. This layer is of greatest concern in shallow snowpack areas in the north and east of the region.

Weather Summary

Saturday Night

Partly cloudy with isolated flurries; 0-3 cm / Light south ridgetop wind / Low temperature at treeline around -20 C

Sunday

Mix of sun and cloud / Light south ridgetop wind / High temperature at treeline around -7 C

Monday

Mix of sun and cloud with isolated flurries; 3-5 cm / Strong south ridgetop wind / High temperature at treeline around -7 C

Tuesday

Mix of sun and cloud with isolated flurries; 3-5 cm / Strong southwest ridgetop wind / High temperature at treeline around -4 C

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

  • Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
  • Avoid shallow, rocky areas where the snowpack transitions from thick to thin.
  • Use extra caution around cornices: they are large, fragile, and can trigger slabs on slopes below.
  • Sheltered low elevation terrain will likely offer the best and safest riding today.

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.

Deep Persistent Slabs

Deep Persistent Slab avalanches are the release of a thick cohesive layer of hard snow (a slab), when the bond breaks between the slab and an underlying persistent weak layer deep in the snowpack. The most common persistent weak layers involved in deep, persistent slabs are depth hoar or facets surrounding a deeply buried crust. Deep Persistent Slabs are typically hard to trigger, are very destructive and dangerous due to the large mass of snow involved, and can persist for months once developed. They are often triggered from areas where the snow is shallow and weak, and are particularly difficult to forecast for and manage.