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Avalanche Forecast

Archived

Dec 10th, 2024–Dec 11th, 2024

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

Regions

Glacier.

Ski quality is good at the moment but be on the lookout for slab development.

A persistent weak layer made up of surface hoar or a sun crust is buried 50-70 cm deep. Remote triggering is possible in areas with a slab at or near the surface.

Confidence

Moderate

Avalanche Summary

Natural avalanche activity has tapered off with a few size 1-2.5 avalanches observed in the highway corridor in steep/extreme terrain since Sunday.

Artillery control produced excellent results on Tupper and Macdonald Sat night, with most shots producing sz 2 to sz 3 avalanches from steep start zones, running out onto valley bottom fans. Debris moved fast, likely picking up speed and mass on the buried surface hoar.

Snowpack Summary

50-70cm of new snow sits on a sun crust on steep solar aspects. In sheltered locations, this new snow sits atop large surface hoar. Strong SW winds at the end of the storm created surface slab conditions on exposed Treeline and Alpine slopes.

There is a dense, well-settled mid-pack without any significant weak layers.

The Nov 9 crust is down 1-1.5m. The base of the snowpack is comprised of several dense, melt-freeze rain crusts formed in October.

Weather Summary

A ridge of high pressure continues, with no significant change until the weekend.

Wed: Mainly cloudy with isolated flurries. Trace precipitation. Alpine high -4 °C. Ridge wind SW 10 km/h. Freezing level (FLZ)1400 m.

Thurs: Cloudy with sunny periods. No precipitation. Alpine high -4. Ridge wind SW 10. (FLZ) 1200 m.

Friday Mainly cloudy with isolated flurries. Trace precipitation. Wind SW 15-35. (FLZ) 1100 m

Terrain and Travel Advice

  • Be aware of the potential for remote triggering and large avalanches due to buried surface hoar.
  • Make conservative terrain choices and avoid overhead hazard.
  • Watch for newly formed and reactive wind slabs as you transition into wind-affected terrain.

Problems

Persistent Slabs

Persistent Slab avalanches are the release of a cohesive layer of snow (a slab) in the middle to upper snowpack, when the bond to an underlying persistent weak layer breaks. Persistent layers include: surface hoar, depth hoar, near-surface facets, or faceted snow. Persistent weak layers can continue to produce avalanches for days, weeks or even months, making them especially dangerous and tricky. As additional snow and wind events build a thicker slab on top of the persistent weak layer, this avalanche problem may develop into a Deep Persistent Slab.