Avalanche Forecast

Issued: Dec 14th, 2020 4:00PM

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

Avalanche Canada kdevine, Avalanche Canada

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Storm slabs may become more reactive to human triggering throughout the day as new snow piles up. Watch for signs of instability such as whumphing, cracking and recent avalanches.

Summary

Confidence

Moderate - Uncertainty is due to the limited number of field observations. Forecast snowfall amounts are uncertain.

Weather Forecast

MONDAY NIGHT - Cloudy with scattered flurries, up to 5 cm / light southwest wind / alpine low temperature near -10 

TUESDAY - Cloudy with flurries, 5-10 cm / southwest wind, 15-30 km/h / alpine high temperature near -6 

WEDNESDAY - Mainly cloudy with flurries, 5 cm / southwest wind, 20-30 km/h / alpine high temperature near -6 

THURSDAY - Cloudy with flurries, 5 cm / light southwest wind / alpine high temperature near -5

Avalanche Summary

Over the past few days there have been a few reports of small avalanches above the recently buried surface hoar and crust layers. These include several dry loose avalanches in steep terrain and a size 1 skier triggered avalanches in Glacier National Park (see the photo in this MIN report). While these avalanches have limited destructive potential, we anticipate this developing into a more concerning problem with the arrival of more snow.

Snowpack Summary

Up to 15 cm of new snow is expected between Monday night and Tuesday afternoon, bringing total recent snowfall amounts to 15-35 cm. This snow sits on a weak layer that exists as either a crust or feathery surface hoar. Most areas in the region are reporting that the new snow sits on a crust, while areas with surface hoar are more likely to be found at upper elevations in the Selkirks.

A buried crust can be found in the lower snowpack (50-150 cm deep) with some reports of weak snow around this crust. There have been no recent avalanches reported on this layer, however occasional test results indicate that it may be reactive to human triggers on shallow rocky features at upper elevations.

Terrain and Travel

  • Investigate the bond of the recent snow before committing to your line.
  • Be careful with wind loaded pockets, especially near ridge crests and roll-overs.
  • Watch for signs of instability like whumpfing, hollow sounds, shooting cracks or recent avalanches.

Problems

Storm Slabs

An icon showing Storm Slabs

15-35 cm of snow may be blown into unstable slabs. In certain areas this snow may be poorly bonded to underlying layers of surface hoar and/or crusts. This is most likely a problem at treeline and alpine elevations in areas that received more than 20 cm of snow in the past week.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 2

Valid until: Dec 15th, 2020 4:00PM