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Avalanche Forecast

Archived

Jan 6th, 2023–Jan 7th, 2023

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

Regions

Glacier.

Watch for fresh windslabs in exposed alpine terrain.

We have an unusually weak and faceted snowpack at Rogers Pass. Sticking to lower angled, supported slopes, and avoiding shallow rocky areas, will reduce your chances of triggering the deeper persistent weak layers.

Confidence

Moderate

Avalanche Summary

On Thursday, the Macdonald gullies (on the steep North Face) produced several large avalanches during a brief wind spike in the morning, notably gully #6 produced a size 3 slab avalanche. There was also a loose dry avalanche which triggered a size 2 deep slab avalanche on the Bonney glacier.

There was a skier triggered slab avalanche on Avalanche Crest on Wednesday.

On Monday a size 2 avalanche was remotely triggered from a shallow snowpack area on Bruins Ridge. These types of spooky avalanches continue to be reported in nearby areas, and are causing anxiety amongst avalanche forecasters! Stay away from thin, rocky areas, and ensure no other skiers are below you before entering your line.

Snowpack Summary

The top 30cm of snow is settling with warmer temps. Southwesterly winds Friday have created fresh wind slabs in exposed areas at upper elevations. Steeper SW and W aspects have a thin sun crust on the surface.

The December 23rd facet interface, down ~70cm, is gaining strength, but remains a concern in shallow snowpack areas.

The November 17th facet/crust/surface hoar layer is still active in snowpack tests, exhibiting 'sudden collapse' or 'sudden planar' results, and producing isolated large avalanches in neighboring areas.

Weather Summary

A surface ridge of high pressure remains over the region on Saturday, which will bring cloudy skies and scattered flurries with 5-10cm of snow by Sunday morning. Alpine temps range from -8 to -3 with a freezing level of 900m. Ridgetop winds will be from the South at 15-35km/hr.

Terrain and Travel Advice

  • Avoid thin areas like rock outcroppings where you're most likely to trigger avalanches failing on deep weak layers.
  • If triggered, wind slabs avalanches may step down to deeper layers resulting in larger 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.

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.

Deep Persistent Slabs

Deep Persistent Slab avalanches are the release of a thick cohesive layer of hard snow (a slab), when the bond breaks between the slab and an underlying persistent weak layer deep in the snowpack. The most common persistent weak layers involved in deep, persistent slabs are depth hoar or facets surrounding a deeply buried crust. Deep Persistent Slabs are typically hard to trigger, are very destructive and dangerous due to the large mass of snow involved, and can persist for months once developed. They are often triggered from areas where the snow is shallow and weak, and are particularly difficult to forecast for and manage.