Avalanche Forecast

Issued: Jan 25th, 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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Sheltered, shady terrain may still hold soft snow that doesn't sit on top of a crust. 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

Tuesday Night: Partly cloudy. Possible trace of snow expected. Moderate west wind trending to extreme northwest at higher elevations. Freezing levels fall to near valley bottom. Alpine low around -7 C.

Wednesday: Mostly sunny, localized cloud cover. No new snow expected. Light northwest wind trending to extreme northwest at higher elevations, decreasing through the day. Freezing levels near valley bottom overnight, rising to 800 m by the afternoon. Alpine high around -7 C.

Thursday: Mostly sunny. No new snow expected. Light southwest winds trending to strong northwest at higher elevations. Freezing levels at valley bottom overnight, rising to 800 m by the afternoon. 

Friday: Scattered clouds. No new snow expected. Light southwest wind trending to extreme west at higher elevations. Freezing levels at valley bottom overnight, rising to 1000 m by the afternoon.

Avalanche Summary

On Tuesday, neighbouring Waterton National Park reported a few small to large natural windslab avalanches from steep, alpine features, and a couple of small, rider triggered windslab avalanches on reverse loaded, steep rolls.

 

No new avalanches were reported on Sunday or Monday.

On Saturday, neighbouring Waterton National Park reported a few natural windslab avalanches to size 2 on solar aspects in the alpine. 

Additionally, a Mountain Information Network (MIN) post from west of Elkford reported a large avalanche that looks to be a couple of days old due to snow on top of the debris. It failed below some cliffs in the alpine and ran into flatter terrain below. See here for more details.

Snowpack Summary

On the surface, expect to find a thin suncrust on solar aspects, especially in the high alpine, and below treeline, where temperatures may have gotten above zero over the weekend. 

Moderate winds have redistributed any snow available for transport. 10-20cm of wind slabs can be found in lee features, while windward terrain below 2100 m is likely stripped down to the January 12th melt-freeze crust.

One common theme throughout the region is that the mid-pack is well settled above the deeper December crust/facet interface which is currently the primary concern in the snowpack.

The early December crust is now generally down 80-150 cm. This layer is found widespread through the region but with varying test results. Recent snowpack tests have shown more reactivity in shallower snowpack areas. This indicates that there is potential to trigger this weak layer from a thin spot which may propagate to a thicker slab within the snowpack, creating a very large avalanche. Daytime warming, solar radiation, and cornice fall could all 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 80-150 cm deep. 

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.  

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

The three most recent avalanches on this layer were reported on January 20th. They occured on large alpine features below rock faces. 

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

2 - 3.5

Valid until: Jan 26th, 2022 4:00PM