Regions
Kootenay Boundary.
Confidence
Fair - Timing, track, or intensity of incoming weather system is uncertain
Weather Forecast
Overnight and Thursday: Freezing level dropping to valley bottoms overnight and the rising up to 1800 metres during the day. Becoming overcast with moderate to strong Southwest winds and flurries or light snow.Friday: Freezing level dipping down to about 1500 metres and the rising up to about 1700 metres. Moderate Westerly winds with periods of snow at higher elevations.Saturday: Little or no drop in freezing overnight. Continued moderate to strong Westerly winds combined with light snow above 1600 metres.
Avalanche Summary
Some storm slab avalanches that were 10-40 cm deep ran naturally or were skier triggered up to size 2.0. Snowballing and loose wet slides up to size 1.5 were also reported from solar aspects.
Snowpack Summary
Forecast new snow and Southwest wind may result in a new storm slab. High freezing levels may limit crust recovery before the new snow arrives. There are a few crusts in the snowpack that we are following. The March 25th crust is now down about 20-30 cm buried below a well settled layer of recent snow. The March 10th crust is buried down 60-90 cm and is reported to be widespread across the region up to about 2000 metres elevation. The facet/crust persistent weakness buried at the beginning of February is now down 70 - 200cm, and has been highly variable in terms of reactivity. In areas where the strong and supportive crust exists, triggering this layer has become unlikely. Avalanches releasing on this deeply buried weak layer could be very large and destructive.
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.
Deep Persistent Slabs
Deep Persistent Slab avalanches are the release of a thick cohesive layer of hard snow (a slab), when the bond breaks between the slab and an underlying persistent weak layer deep in the snowpack. The most common persistent weak layers involved in deep, persistent slabs are depth hoar or facets surrounding a deeply buried crust. Deep Persistent Slabs are typically hard to trigger, are very destructive and dangerous due to the large mass of snow involved, and can persist for months once developed. They are often triggered from areas where the snow is shallow and weak, and are particularly difficult to forecast for and manage.