Avalanche Forecast

Archived

Dec 5th, 2023–Dec 6th, 2023

Alpine

Natural and human triggered avalanches likely.

Treeline

Natural avalanches possible, human triggered probable.

Below Treeline

Natural avalanches unlikely, human triggered possible.

Alpine

Natural avalanches possible, human triggered probable.

Treeline

Natural avalanches possible, human triggered probable.

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.

Regions

Kananaskis, Bow Valley, Highwood Pass, North 40, Spray - KLakes.

Warm temperatures, rain and wind slabs are increasing the avalanche hazard.

Avoid all avalanche terrain.

Confidence

Low

Avalanche Summary

Visibility was poor for observing but one size 2 avalanche was noted in the Commonwealth area near tree line. This is likely due to the rain soaked snow.

Snowpack Summary

A major weather event is happening with warm temperatures and moderate snow amounts.

Expect rain soaked up to 2300m. With the forecast snow for Tuesday night, along with SW winds, expect wind slabs to be building in the alpine, especially near lee features and cross loaded gullies. These new wind slabs are only adding load to an incredibly weak base comprised of facets, depth hoar, and crusts.

Weather Summary

Tuesday night: 5-10cm of snow is forecast to fall with the overnight freezing level of 2100m.

Wednesday during the day: 2-4cm throughout the day with SW winds of 30-40km/h. Freezing level will be around 2000m.

Wednesday night: 10-15cm throughout the day with winds diminishing to 5-10km/h from the NNW. Freezing level dropping to 1300m.

Thursday: Cooling trend with flurries and light West winds.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

Avoid all avalanche terrain during periods of heavy loading from new snow, wind, or rain.
Approach lee and cross-loaded slopes with caution.

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.

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.