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Avalanche Forecast

Archived

Dec 11th, 2022–Dec 12th, 2022

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 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.
Below Treeline
Natural avalanches unlikely.

Regions

South Rockies, Bull, Crowsnest North, Crowsnest South, Elkford East, Elkford West.

Much of our region has been wind-affected. Expect wind slabs of various sizes to be reactive to rider triggering.

A weaker layer further down in the snowpack is still reactive.

Avoid pockets of wind-loaded terrain and watch out for rocks exposed by the wind.

Confidence

Moderate

Avalanche Summary

On Saturday, reports of an animal triggering a natural size two avalanche were submitted from the northern part of our region. This avalanche was released on the weak layer created in mid-November. This was in the north of our area. Our neighbours even further north in Kananaskis Country reported evidence of reactivity of this layer on convex rolls. This same layer continues to be reactive in snowpack testing.

Local operators reported on Sunday that they were getting lots of reactivity from pockets of wind-loaded terrain. Many smaller wind slab avalanches were produced.

If you head into the backcountry, support your community by submitting a report to the Mountain Information Network. Thank you to those who have.

Snowpack Summary

Since Thursday night up to 20 cm has accumulated in some parts of our region. In the alpine and at the treeline strong westerly winds have moved much of this snow around. The new snow and new wind slabs are covering a variety of surfaces that they may not have bonded to yet. It is expected that the wind has built wind slabs upon wind slabs in some areas while in other areas the wind will have stripped away the majority of the snow.

Where the wind had less of an impact on the snow you can expect to find around 10 to 20 cm of soft snow sitting on 30 to 40 cm of more settled snow. Buried 45 to 65 cm down lies a weak layer comprising of surface hoar and facets. This layer has been shown to be reactive in snowpack tests and showed be kept on your radar for the time being. Further down the snow is sugary and faceted with a rain crust near the ground but this lower snowpack appears to be consolidating.

Total snowpack depths at treeline elevations are 75 to 155 cm.

Weather Summary

Sunday Night

Mostly cloudy, up to 7 cm accumulation, winds northeast 10 km/h, -10 C at 1500 m.

Monday

A mix of sun and cloud, trace accumulation, winds northeast 15 km/h, -8 C at 1500 m.

Tuesday

A mix of sun and cloud, trace accumulation, winds northeast 15 km/h, -8 C at 1500 m.

Wednesday

Mostly cloudy, 2 cm accumulation, winds west 10 km/h, -5 C at 1500 m.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

  • Back off if you encounter whumpfing, hollow sounds, or shooting cracks.
  • If triggered, wind slabs avalanches may step down to deeper layers resulting in larger avalanches.
  • Avoid freshly wind loaded features, especially near ridge crests, roll-overs and in steep terrain.
  • Caution around convexities or sharp changes in 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.

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.