Avalanche Forecast

Issued: Dec 14th, 2020 4:00PM

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

Avalanche Canada ahanna, Avalanche Canada

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Heavy snowfall and strong southwest winds are forming reactive slabs. It's a good day to stick to conservative terrain.

Summary

Confidence

Moderate -

Weather Forecast

Monday night: 10-20 cm new snow, wind increasing to strong southwest, freezing level 800 m.

Tuesday: 10-20 cm new snow, strong southwest ridgetop wind, alpine high -2 C, freezing level 1200 m.

Wednesday: 15-20 cm new snow, moderate to strong southwest ridgetop wind, alpine high 0 C, freezing level 1300 m.

Thursday: 20-25 cm new snow overnight, moderate northwest wind, alpine high 0 C, freezing level 1300 m.

Avalanche Summary

On Friday and Saturday, we received reports of natural and skier controlled loose dry size 1 and storm slabs size 1-1.5. See photos of some touchy remote triggered slabs during the storm Friday in this great MIN from Pump Peak

Have you been out and about in the mountains? If so please submit your observations to the Mountain Information Network (MIN). It doesn't have to be technical - photos are especially helpful! Thank you so much for all the great MINs submitted so far!

Snowpack Summary

20-40 cm falling on the North Shore mountains by end of the day Tuesday brings storm totals to 30-60 cm. This recent snow sits on a thin melt freeze crust on solar aspects, and possibly over a layer of weak surface hoar crystals in wind sheltered areas. This MIN from Saturday includes photos of the surface hoar before it was buried.

A layer of weak crystals sitting on a 20 cm thick crust is now covered by 40-80 cm of snow. We have had our eyes on it since it became buried last week. We haven't seen any avalanches on this layer since Saturday and snowpack tests since Sunday have shown no results at this interface.

We have very little data and a lot of uncertainty around alpine conditions in the region. If you go out in the mountains, please let us know what you see via the Mountain Information Network (MIN)

Terrain and Travel

  • Watch for fresh storm slabs building throughout the day.
  • As the storm slab problem gets trickier, the easy solution is to choose more conservative terrain.
  • Be aware of the potential for larger than expected storm slabs due to the presence of buried surface hoar.

Problems

Storm Slabs

An icon showing Storm Slabs

20-40 cm falling on the North Shore mountains by end of the day Tuesday brings storm totals to 30-60 cm. Storm slabs may be especially reactive in wind sheltered terrain where storm snow sits on surface hoar. Caution around wind loaded pockets just below ridge crests and roll-overs.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely

Expected Size

1 - 2

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