Snowfall amounts may be less in the Southern part of the forecast region. If this holds true then the Kootenay Boundary forecast may be more applicable.
Confidence
Moderate - Forecast snowfall amounts are uncertain on Monday
Weather Forecast
A strong westerly flow is driving a series of Pacific frontal systems through the Interior regions tonight through the week. Each system will be a bit stronger bringing moderate to heavy snow amounts and strong winds.Sunday Night: Snow 10-20 cm with alpine temperatures -12 and southwest winds 50-80 km/hMonday: Snow 15-25 cm with alpine temperatures near -9 and ridgetop winds southwest 30-70 km/h.Tuesday: Snow 5-15 cm with alpine temperatures -9 and ridgetop winds light from the southwest.Wednesday: Light flurries with alpine temperatures -8 and ridgetop winds 30 gusting to 60 km/h.
Avalanche Summary
On Saturday isolated wind slabs up to size 2.5 were reported. Forecast strong winds and heavy snow will build touchy storm slab problems.
Snowpack Summary
10-20 cm of storm snow (more to come!) sits over a plethora of old snow surfaces including wind effected snow, faceted (sugary) crystals and surface hoar crystals and a thin sun crust on some steep solar aspects. The new snow will likely have a poor bond to these surfaces. Deeper in the snowpack exist two layers that may become reactive through these 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.