Avalanche Forecast

Issued: Jan 24th, 2022 4:00PM

The alpine rating is moderate, the treeline rating is moderate, and the below treeline rating is low. Known problems include Deep Persistent Slabs.

Avalanche Canada bchristie, Avalanche Canada

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Continually gather snowpack information as you hunt for soft snow. Isolated weak layers in the upper snowpack could fail under the weight of a rider. Avoid shallow rocky start zones where you could trigger a deep persistent slab.

Summary

Confidence

High - Confidence is due to a stable weather pattern with little change expected.

Weather Forecast

Monday Night: Partly cloudy with a clear period. No new snow expected. Light northeast wind with periods of strong at higher elevations. Freezing levels rise to 1000 m, alpine low around -6 C.

Tuesday: Mostly cloudy by the afternoon. Possible trace of snow expected. Moderate southwest wind trending to strong west at higher elevations. Freezing levels to 750 m by the afternoon. Alpine high around -6 C.

Wednesday: Partly cloudy. Possible trace of snow expected. Moderate southwest wind, trending to extreme northwest at higher elevations. Freezing levels drop to valley bottom overnight, rise back to 750 m by the afternoon. 

Thursday: Mostly sunny. No new snow expected. Light southwest wind trending to strong northwest at higher elevations. Freezing level at valley bottom overnight, rising to 750 m by the afternoon. 

Avalanche Summary

No new avalanches were reported on Sunday or Monday before 4pm.

On Saturday, avalanche control with explosives produced a couple of small windslab avalanches around treeline. Also, neighbouring Waterton National Park reported a few natural windslab avalanches to size 2 on solar aspects in the alpine.

Snowpack Summary

Surface hoar up to 10 mm has been reported around Fernie. At this time it is unknown if this surface hoar growth is more widespread. Patchy sun crust may exist on steep, solar aspects.

The upper snowpack consists of windslabs 20-60 cm deep in exposed terrain, and 15-20 cm of settling storm snow from last week.

Around 2200 m and below, these windslabs overlie a crust buried on January 18th, which caps a dense 15 to 30 cm of settled snow. On some windward slopes, the wind has scoured the surface back down to this crust. The crust varies with aspect and elevation from thin (2 cm thick) in the alpine to (4 cm) thick below treeline. 

The midpack is strong and well consolidated above the early December crust/ facet interface.  

The most notable layer of concern in the snowpack is a widespread crust that was formed in early December and is now down 100-270 cm. With warming last week this deep persistent slab problem woke up and produced several very large avalanches. Daytime warming, solar radiation, smaller avalanches, and cornice fall could continue to play a role in triggering deep persistent slabs. 

Terrain and Travel

  • In areas where deep persistent slabs may exist, avoid shallow or variable depth snowpacks and unsupported terrain features.
  • If you are increasing your exposure to avalanche terrain, do it gradually as you gather information.
  • Watch for signs of instability like whumpfing, hollow sounds, shooting cracks or recent avalanches.
  • Avoid terrain traps where the consequence of any avalanche could be serious.

Problems

Deep Persistent Slabs

An icon showing Deep Persistent Slabs

The early December crust can be found 100-270 cm deep.

This deep persistent slab problem has been less active over the weekend, but we have been reminded multiple times in the last month that this layer could remain a concern all winter.

Thin rocky start zones are the most likely place to trigger this layer. Also, daytime warming, solar radiation, cornice fall, and step-downs from smaller avalanches could increase the chance of an avalanche on this layer.  

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

2 - 3.5

Valid until: Jan 25th, 2022 4:00PM