Avalanche Forecast
Issued: Jan 4th, 2023 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Persistent Slabs and Deep Persistent Slabs.
CG,
Avalanche Canada
We have a very weak, faceted, basal layer in our snowpack at Rogers Pass.
Avoid thin, rocky, unsupported features where one could sink into the sugary facets, potentially triggering the deeper persistent weak layers.
Summary
Confidence
Moderate
Avalanche Summary
Several natural sz 2 slab and loose avalanches were observed in the highway corridor on Tuesday and Wednesday. Most were from steep, rocky S aspects, with the exception of a larger slab from Macdonald Gully 10.
On Monday a size 2 avalanche was remotely triggered from a shallow snowpack area on Bruins Ridge. These are the spooky avalanches that are causing anxiety amongst avalanche forecasters! Stay away from thin, rocky areas!
Snowpack Summary
The top 30cm of snow is low-density and provides great powder turns. Steeper SW and W aspects have a thin sun crust on the surface. The Dec 23 facet interface, down ~70cm, is gaining strength. The Nov 17 facet/crust/surface hoar layer is still active in snowpack tests, exhibiting 'sudden collapse' or 'sudden planar' results.
Weather Summary
Clouds, flurries, and slightly elevated freezing levels (FZL) will be the norm for the next few days. No major storms in the foreseeable future. Darn, eh!?
Thurs: mainly cloudy, trace snow, Alp high -2*C, 1600m FZL, light S winds
Fri: cloud with scattered flurries, 5cm, Alp high -4*C, 1500m FZL, light/gusty SW winds
Sat: flurries, 5cm, Alp high -4*C, 1600m FZL, light SW winds
Terrain and Travel Advice
- Avoid thin areas like rock outcroppings where you're most likely to trigger avalanches failing on deep weak layers.
- Back off if you encounter whumpfing, hollow sounds, or shooting cracks.
Problems
Persistent Slabs
30-60cm of settled storm snow buries the Dec 23 facet interface. This layer will be a concern in steep terrain, on convex rolls, or areas where the snowpack is unsupported (pillows, hanging snow fields, etc.).
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Deep Persistent Slabs
The Nov 17 layer, down 60-120cm, consists of facets, a rotting crust, and decomposing surface hoar. This layer still shows hard, sudden collapse/planar results in snowpack tests. Though becoming less likely to trigger, the resulting avalanche would be quite large.
Aspects: All aspects.
Elevations: Treeline, Below Treeline.
Likelihood
Expected Size
Valid until: Jan 5th, 2023 4:00PM
