Avalanche Forecast

Archived

Nov 29th, 2022–Nov 30th, 2022

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

Jasper, Brazeau, Churchill, Cirrus-Wilson, Fryatt, Icefields, Maligne, Marmot, Miette Lake, Pyramid.

A buried surface hoar layer exists 30cm down at tree line and below in sheltered terrain. Solar crust also down 30cm can be found on steep solar aspects. Whumphing and cracking have been observed on both of these layers of concern; both should be evaluated carefully while in avalanche terrain.

Confidence

Moderate

Avalanche Summary

Field team in the Icefield area on Monday observed shooting cracks and whumphing on surface hoar layer down 30 cm at tree line and below in sheltered east to northerly aspects. Nov 27th MIN report confirms the presence of the same layer of concern in the Maligne region.Icefield Parkway and Maligne road patrol noted no new natural avalanche activity on Monday.

Snowpack Summary

25-35cm overlies a surface hoar-Facet-crust combination layer depending on aspect and elevation. 6-10mm surface hoar is found preserved in sheltered treeline locations. Height of snow ranges from 60 to 100cm.

Weather Summary

Wednesday - isolated flurries with trace to 5cm possible; winds variable and light with an alpine high of -20C. Clearing Thursday and through the weekend with below seasonal temperatures persisting.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

Approach steep open slopes at and below treeline cautiously, buried surface hoar may exist.

Problems

Persistent Slabs

Persistent Slab avalanches are the release of a cohesive layer of snow (a slab) in the middle to upper snowpack, when the bond to an underlying persistent weak layer breaks. Persistent layers include: surface hoar, depth hoar, near-surface facets, or faceted snow. Persistent weak layers can continue to produce avalanches for days, weeks or even months, making them especially dangerous and tricky. As additional snow and wind events build a thicker slab on top of the persistent weak layer, this avalanche problem may develop into a Deep Persistent Slab.

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.

Loose Dry

Loose Dry avalanches are the release of dry unconsolidated snow and typically occur within layers of soft snow near the surface of the snowpack. These avalanches start at a point and entrain snow as they move downhill, forming a fan-shaped avalanche. Other names for loose-dry avalanches include point-release avalanches or sluffs.