North Rockies Avalanche Forecast - February 23, 2021

There was a report of an avalanche fatality in the Hasler area on Saturday. Heavy snowfall over the weekend has increased the likelihood and consequence of triggering a persistent slab avalanche. Adopt a conservative approach to terrain selection in the coming days.

Tuesday

Alpine - High
Treeline - Considerable
Below treeline - Considerable

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Wednesday

Alpine - Considerable
Treeline - Considerable
Below treeline - Considerable

Thursday

Alpine - Considerable
Treeline - Considerable
Below treeline - Considerable

Avalanche Summary

There is a preliminary report of an avalanche fatality in the Hasler area on Saturday. The details are still limited at this time, but the incident happened on a northeast aspect between 1400 and 1500m. The avalanche was a size 2. The fracture line was estimated to be 50-100 cm and is suspected to have been a persistent slab avalanche running on a weak layer of surface hoar. Click here to link to a report on the incident.

There was likely a widespread natural avalanche cycle on Sunday and Monday as a result of heavy loading from snow and wind.

There were numerous reports of cracking and whumpfing on the persistent slab mentioned in the problem section over the past several days. This MIN post outlines the issue nicely.

Snowpack Summary

40-60+cm of new snow fell through the weekend with strong southwest and west winds to form reactive storm slabs and wind slabs in alpine lees.

The snow has increased the load on a widespread persistent surface hoar layer. The layer is likely 80-120 cm deep near Renshaw and 60-100 cm deep around Torpy and further north. Reports suggest this layer is most prevalent around treeline elevations, but likely reaches into the alpine and down into the trees too. It may sit above a crust below 1600 m. The likelihood of triggering this layer has likely increased with the new load from the snowfall. For sure the consequence of triggering this layer is high.

There are presently no deeper concerns in the snowpack.

Weather Forecast

TUESDAY - Mix of sun and cloud, moderate to strong west wind, alpine temperature -7 C.

WEDNESDAY - Cloudy with sunny breaks and isolated flurries, moderate to strong southwest wind, alpine temperature -8 C.

THURSDAY - Snow, accumulation 10-15 cm, moderate west wind, alpine temperature -5.

Travel and Terrain Advice

  • Watch for signs of instability like whumpfing, hollow sounds, shooting cracks or recent avalanches.
  • Be aware of the potential for large avalanches due to the presence of a persistent slab.
  • Storm slabs in motion may step down to deeper layers resulting in large avalanches.
  • In times of uncertainty conservative terrain choices are our best defense.

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A map of the North Rockies. - Avalanche Canada image
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