More snow, strong winds and warmer temperatures are driving the danger ratings. It's a good time to make conservative choices and stick to simple terrain.
Confidence
Moderate - Forecast snowfall amounts are uncertain on Tuesday
Weather Forecast
The Interior is under a strong zonal flow that is responsible for pushing out the cold air and bringing in the snow! We can expect to see an additional two - three systems move across the region through the forecast period.Tuesday: Snow 8-15 cm with freezing levels rising to 1000 m. Alpine temperatures -9 and ridgetop winds 35-60 km/hr.Wednesday: Snow 5 cm with freezing levels dropping to valley bottom. Alpine temperatures -11 and ridgetop winds 30-55 km/hr.Thursday: Snow 5-10 cm with alpine temperatures -9. Ridgetop winds 15-35 km/h.
Avalanche Summary
Loose snow and wind slab avalanches up to size 2 were reported on Monday. Given the weather forecast we can expect to see avalanche activity on Tuesday.
Snowpack Summary
Up to 15 cm of storm snow sits over a plethora of old snow surfaces including stiff wind affected snow, faceted (sugary) crystals and surface hoar crystals that formed in locations sheltered from the wind. The new snow will likely have a poor bond to these surfaces. 20-40 cm below this new snow sits an older buried surface hoar layer, reported from the Dogtooth Range. This layer may me reactive with additional load. The mid-November crust is buried down around 70-90 cm and test results have been variable from sudden failures to no results. In shallower snowpack areas reports indicate that the bond to the crust is weakening. Tracking and monitoring this potentially weak interface is crucial especially as we move forward into this snowy period where the snowpack will see more load.
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.
Loose Dry
Loose Dry avalanches are the release of dry unconsolidated snow and typically occur within layers of soft snow near the surface of the snowpack. These avalanches start at a point and entrain snow as they move downhill, forming a fan-shaped avalanche. Other names for loose-dry avalanches include point-release avalanches or sluffs.