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Avalanche Forecast

Archived

Nov 26th, 2022–Nov 27th, 2022

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 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.

Regions

Glacier.

The avalanche hazard will increase overnight into Sunday as the snow continues to add up. Expect the fresh storm slab and the Nov 17 persistent slab to be sensitive to human triggering.

There are still many early season hazards, like rocks and stumps just below the snow surface. Leave plenty of time to ski out in daylight hours at the end of your day.

Confidence

Moderate

Avalanche Summary

A widespread natural avalanche cycle up to size 2, mainly on the East end of the highway corridor, and an isolated size 3 out of MacDonald Gully 6.

Expecting avalanche activity to increase with continued snowfall into Sunday morning.

Snowpack Summary

25cm of new snow with another 15-20cm overnight will continue to build storm slabs. The Nov 17 persistent slab (surface hoar 5-30mm, facets, and crust) is down 30-50cm. The surface hoar is largest at and below treeline.

The early season snowpack is thin and variable, with an average depth of 50cm at the parking lots, just over a meter at treeline, and up to 130cm in the alpine. These values are below threshold for burying hazards, covering creeks, and bridging crevasses.

Weather Summary

A cold front will move through the region Saturday evening into Sunday morning bringing 15-20cm of new snow and strong SW winds.

Sunday, winds will shift to the West becoming light, while temperatures will begin to drop below -20 in the alpine.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

  • Don't be too cavalier with decision making, storm slabs may remain sensitive to human triggering.
  • Carefully assess open slopes and convex rolls where buried surface hoar may be preserved.
  • Early season avalanches at any elevation have the potential to be particularly dangerous due to obstacles that are exposed or just below the surface.

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.

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.