Storm slabs have been forming above a weak layer in areas where storm snow has crept above threshold depths for avalanching. Travel conditions remain rugged where it hasn't.
Confidence
Moderate - Due to the number of field observations
Weather Forecast
Saturday night: Mainly cloudy with light to moderate west winds.Sunday: Mainly cloudy. Light to moderate west winds. Alpine high temperatures around -5.Monday: Mainly cloudy with isolated, increasingly wet flurries beginning in the afternoon. Moderate to strong southwest winds. Alpine high temperatures around -2 with the freezing level rising to about 2000 metres by evening.Tuesday: Cloudy with continuing wet flurries bringing about 5 cm of new snow to higher elevations. Light rain below about 1600 metres. Alpine high temperatures around -1 to 0 with freezing levels remaining near 2000 metres.
Avalanche Summary
Reports from Friday show a natural avalanche cycle during the Friday overnight period as well as explosives control in the Fernie area producing numerous storm slab releases reaching up to size 2. This avalanche activity was limited to the depth of our new snow, about 25 cm deep.
Snowpack Summary
Moderate to heavy snowfall over Thursday and Friday brought about 30 cm of new snow to the region. This new snow buried a recently formed layer of weak, feathery surface hoar previously found on the snow surface. Below this layer of surface hoar, the new snow has also buried pockets of recently reactive wind slab in wind-exposed alpine and treeline terrain. This wind-affected layer sits above a mixed layer of late-October and early-November melt-freeze crusts and facets. The snowpack is deepest at alpine and treeline elevations, where you might now expect to find total depths of around 70 cm. These depths taper rapidly at lower elevations, where travel conditions remain rugged.
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.