Avalanche forecast

South Rockies

Dec 27 – 28, 2021Avalanche Canada
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Avalanche danger

Wed
Thu
Alpine
2 · Moderate
Treeline
2 · Moderate
Below
2 · Moderate
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Highlights

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

Keep in mind that cold temperatures significantly increase the consequence of even minor injuries in the backcountry.

Avalanche problems

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1.5–2.5

    Recent winds have created wind slabs on a variety of aspects and created a lot of variability in the upper snowpack.

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Unlikely - Possible
    Size
    2–3

    A layer of weak facets (sugary snow) can be found down 60-100 cm over a crust that formed in early December. This layer has produced large avalanches with explosive triggers and has shown reactivity in snowpack tests. A larger trigger such as a skier or snowmobile, may add enough stress to trigger a persistent slab. 

Confidence

Moderate - Uncertainty is due to the fact that persistent slabs are particularly difficult to forecast.

Weather Forecast

MONDAY NIGHT: Partly cloudy / Light to moderate northwest wind / Low of -27

TUESDAY: Mostly cloudy / Light northwest wind / High of -19

WEDNESDAY: Sunny / Light northwest wind / High of -20

THURSDAY: Cloudy / Light northwest wind / High of -19

Avalanche Summary

A couple naturally triggered wind slabs up to size 2 were reported on northwest aspects at treeline on Monday.

Numerous naturally triggered size 1 dry loose avalanches were reported on Sunday. Expect dry loose avalanches (sluffing) running far and fast in steep terrain.

Snowpack Summary

Recent storm totals reached over 120 cm! Expect dry loose avalanches (sluffing) running far and fast in steep terrain.

Recent winds have created wind slabs on a variety of aspects and created a lot of variability in the upper snowpack.

A crust from early December is now 60-100 cm below the surface, and is found up to 2400 m. A layer of weak facets (sugary snow) has been reported above and below this crust. This is the layer of concern in our persistent avalanche problem, snowpack tests are generally showing hard results on this interface, however, areas where avalanches have recently failed on this crust continue to be problematic once reloaded with new snow. 

Below 2300 m, several early-season crusts make up the lower snowpack. Snowpack depths range from 80-150 cm at treeline elevations and taper quickly below 1900m.

Terrain and Travel

  • Use small low consequence slopes to test the bond of the new snow.
  • Pay attention to the wind, once it starts to blow fresh sensitive wind slabs are likely to form.
  • Recent wind has varied in direction so watch for wind slabs on all aspects.
  • If triggered, loose dry avalanches may step down to deeper layers resulting in large avalanches.
  • Be aware of the potential for loose avalanches in steep terrain where snow hasn't formed a slab.

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