Avalanche Forecast

Issued: Dec 23rd, 2020 3:00PM

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

Avalanche Canada matt, Avalanche Canada

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Cold snow and moderate winds demand users pay attention to changing conditions and choose conservative terrain. Give big features more time to settle before exposing yourself to them.

Summary

Confidence

Moderate -

Weather Forecast

Looks like a chilly night in front of us. About -20 tonight on the Spray, but a daytime high of -11 by 3pm. Nothing for snow and winds picking up during the day to about 50km/hr at treeline. Valley winds will be from the SW, while alpine winds will be NW.

Avalanche Summary

While doing the recon for an avalanche control run on EEOR, we noticed a widespread natural cycle mid to late storm. In talking with other people in the park, this cycle went on throughout the forecast region. Most avalanches were in the alpine, about sz 2 to 2.5 and seemed to involve only the storm snow. The EEOR paths themselves (alpine, E asp) had the Nov 5 crust as the failure plain for a couple of avalanches. We did have lots of sympathetically released slides today as well. This suggests the snow is slow to settle and is touchy.

Snowpack Summary

The storm snow has settled quickly and now sits at about 30cm in sheltered areas. Northern winds have taken a toll in open terrain and formed soft windslabs in many areas. The alpine has extensive wind affect at the moment. Alpine and treeline windslabs are now "layered" with slabs of varying vintages. We have seen evidence of avalanches within these layered wind slabs. The Deb 8th and Nov 5th layers are still out there and have reacted in many areas under the new load. We suspect its mostly the Dec 8 crust/facet layer that most guilty, but its also appeared that the Nov 5th has also been a culprit. See the Avalanche Summary for more details.

Terrain and Travel

  • Avoid steep convex slopes.
  • Back off steep and aggressive lines, stick to simple terrain.
  • Be cautious of sluffing.
  • Continue to make conservative terrain choices while the storm snow settles and stabilizes.

Problems

Wind Slabs

An icon showing Wind Slabs

Human triggering is still very likely in terrain greater than 35 degrees. The snow is cold, and slow to settle.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Likely - Very Likely

Expected Size

1.5 - 2.5

Deep Persistent Slabs

An icon showing Deep Persistent Slabs

We did see this as a failure layer today on a the control run. This suggests we are in the hard, but not impossible to trigger phase. 

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible - Likely

Expected Size

2 - 3.5

Valid until: Dec 24th, 2020 3:00PM