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Avalanche Forecast

Archived

Dec 12th, 2020–Dec 13th, 2020

Alpine
Natural avalanches possible, human triggered probable.
Treeline
Natural avalanches unlikely, human triggered possible.
Below Treeline
Natural avalanches unlikely.
Alpine
Natural avalanches unlikely, human triggered possible.
Treeline
Natural avalanches unlikely, human triggered possible.
Below Treeline
Natural avalanches unlikely.
Alpine
Natural avalanches possible, human triggered probable.
Treeline
Natural avalanches unlikely, human triggered possible.
Below Treeline
Natural avalanches unlikely.

Regions

South Coast.

Strong southeast winds are forecast overnight into Sunday morning and there is plenty of soft snow to blow around up there. Watch for fresh wind slabs in lee features in the alpine and upper treeline. 

Confidence

Moderate - Uncertainty is due to the speed, direction, or duration of the wind and its effect on the snowpack.

Weather Forecast

Saturday night: Increasing cloud, strong southeast ridgetop wind, freezing level rising to 1500 m.

Sunday: 5-15 cm new snow, light to moderate southwest to southwest ridgetop wind, alpine high -2C, freezing level drops to 700 m.

Monday: 5-10 cm new snow, light southwest ridgetop wind, alpine high -2 C, freezing level 1000 m.

Tuesday: 20-30 cm new snow, strong southwest ridgetop wind, alpine high -1 C, freezing level 1200 m.

Avalanche Summary

As snow fell Friday morning, we received reports of skier controlled loose dry avalanches up to size 1 at Seymour. Touchy remote triggered storm slabs size 1-1.5 were also reported on northerly aspects in this great MIN from Pump Peak.

Over the weekend, we expect to see more storm slab avalanche activity as the snow settles in the sun. The underlying crust makes a slick bed surface for avalanches to run on.

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

Check out North Shore Rescue's detailed snowpack conditions report from Friday here.

10-15 cm of low density new new snow is forecast to fall through the day Sunday. Strong southeast overnight winds have likely redistributed 20-30 cm of recent snow into wind slabs in leeward terrain features. This recent snow overlies a layer of weak crystals sitting on a thick crust. If triggered, the crust makes a slick bed surface for avalanches.

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

  • Recent new snow may be hiding windslabs that were easily visible before the snow fell.
  • Avoid freshly wind loaded features, especially near ridge crests, roll-overs and in steep terrain.
  • Closely monitor how the new snow is bonding to the crust.
  • Keep in mind the crust offers an excellent bed surface for avalanches.

Problems

Wind Slabs

Wind Slab avalanches are the release of a cohesive layer of snow (a slab) formed by the wind. Wind typically transports snow from the upwind sides of terrain features and deposits snow on the downwind side. Wind slabs are often smooth and rounded and sometimes sound hollow, and can range from soft to hard. Wind slabs that form over a persistent weak layer (surface hoar, depth hoar, or near-surface facets) may be termed Persistent Slabs or may develop into Persistent Slabs.