More snow, strong winds and warmer temperatures are driving the danger ratings. It's a good time to stick to simple non-avalanche terrain.
Confidence
Moderate - Forecast snowfall amounts are uncertain on Tuesday
Weather Forecast
The Interior mountains are 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 that will move across the region through the forecast period.Tuesday: Snow 10-20 cm with freezing levels rising to 1000 m. Alpine temperatures -6 and ridgetop winds 35-75 km/hr.Wednesday: Light flurries with freezing levels dropping to valley bottom. Alpine temperatures -11 and ridgetop winds 30-45 km/hr.Thursday: Snow 5-10 cm with alpine temperatures -11. Ridgetop winds 15-35 km/h.
Avalanche Summary
On Monday numerous natural and rider triggered slab avalanches up to size 3 were reported. Given the weather forecast we can expect to see natural avalanche activity continue Tuesday.
Snowpack Summary
Up to 35 cm of storm snow (more to come!) sits over a plethora of old snow surfaces including wind affected snow, faceted (sugary) crystals, surface hoar crystals and a thin sun crust on steep solar aspects. The new snow will likely have a poor bond to these surfaces. Deeper in the snowpack exist two layers that could become reactive through the next series of storms. The first being a spotty surface hoar layer that sits 30-40 cm down and the mid-November crust that sits 100-200 cm down. Recent test results on these layers have varied from moderate and sudden to hard and resistant, and in some cases no result. In shallower snowpack areas faceting is happening below and above the crust. Tracking and monitoring this potentially weak interface is crucial especially while it's being loaded by new snow.
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.