Avalanche Forecast
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.
Avalanche Problems
Wind Slabs
Gusty winds and warming temps have built fresh windslabs in exposed areas in the alpine. If triggered these wind slabs could step down to deeper instabilities.
Aspects: All aspects.
Elevations: Alpine.
Likelihood: Possible
Expected Size: 1 - 2
Persistent Slabs
30-60cm of settled storm snow buries the Dec 23 facet interface. This layer will be a concern in thin rocky areas, on convex rolls, or in areas where the snowpack is unsupported (pillows, hanging snow fields, etc.).
Aspects: All aspects.
Elevations: All elevations.
Likelihood: Unlikely - Possible
Expected Size: 1 - 2.5
Deep Persistent Slabs
The Nov 17 layer, down 60-120cm, consists of facets, a rotting crust, and decomposing surface hoar. Though becoming less likely to trigger, the resulting avalanche would be quite destructive. Managing this type of problem requires a disciplined approach
Aspects: All aspects.
Elevations: All elevations.
Likelihood: Unlikely - Possible
Expected Size: 2 - 3.5