Dashboard Regions Weather Stations Radar Alerts Glossary
Contact About
Log In

Register for an account and never miss a forecast again!

Register

Avalanche Forecast

Archived

Dec 11th, 2020–Dec 12th, 2020

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

Storm slabs sitting over a crust will be especially sensitive to triggering with the sun shining on Saturday.

Confidence

Moderate - Uncertainty is due to the limited number of field observations.

Weather Forecast

Friday night: Clear, light northeast ridgetop wind, freezing level 600 m.

Saturday: Sunny, light variable ridgetop wind, alpine high -1 C, freezing level 1200 m.

Sunday: Around 10 cm new snow, light to moderate southwest wind, alpine high -2C, freezing level 1000 m.

Monday: 10-15 cm new snow, light southwest wind, alpine high -2 C, freezing level 900 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 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 here.

In the North Shore mountains, 20-30 cm of quite low density snow overlies a layer of weak crystals sitting on a monster crust which was formed during the atmospheric river early in the week. As the sun comes out Saturday, rapid settlement and accelerated slab development over the weak layer will make storm slabs more sensitive to triggering. If triggered, the crust makes a fast bed surface for avalanches to run far.

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 changing conditions today, storm slabs may become increasingly reactive.
  • Closely monitor how the new snow is bonding to the crust.
  • Keep in mind the crust offers an excellent bed surface for avalanches.
  • Avoid exposure to steep, sun exposed slopes, especially when the solar radiation is strong.
  • Avoid freshly wind loaded features, especially near ridge crests, roll-overs and in steep terrain.

Problems

Storm Slabs

Storm Slab avalanches are the release of a cohesive layer (a slab) of new snow that breaks within new snow or on the old snow surface. Storm-slabs typically last between a few hours and few days (following snowfall). Storm-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.