Natural avalanches possible, human triggered probable.
Treeline
Natural avalanches possible, human triggered probable.
Below Treeline
Natural avalanches possible, human triggered probable.
Alpine
Natural avalanches possible, human triggered probable.
Treeline
Natural avalanches possible, human triggered probable.
Below Treeline
Natural avalanches possible, human triggered probable.
Alpine
Natural avalanches possible, human triggered probable.
Treeline
Natural avalanches possible, human triggered probable.
Below Treeline
Natural avalanches possible, human triggered probable.
Regions
South Columbia.
The South Columbia received highly variable snowfall amounts in the storm with the highest amounts near the Revelstoke area. Hazard is likely HIGH in the mountains near Revelstoke. South of Trout Lake is likely well represented by this bulletin.
Confidence
Moderate - Forecast snowfall amounts are uncertain
Weather Forecast
FRIDAY NIGHT - Flurries, 10-15 cm / southwest winds, 30-50 km/h / alpine low temperature near -7SATURDAY - Cloudy with scattered flurries, 3-5 cm / southwest winds 20-30 km/h / alpine high temperature near -7SUNDAY - Mainly cloudy with isolated flurries, 5 cm / southeast winds 10-15 km/h / alpine high temperature near -12MONDAY - Mainly cloudy / northeast winds, 10-15 km/h / alpine high temperature near -14
Avalanche Summary
Field observations were limited on Friday, but a widespread natural avalanche cycle, as well as numerous human triggered avalanches to size 1.5 were reported.On Tuesday, in the neighboring Glacier National Park region, a size 3 avalanche was skier triggered on a steep southeast facing slope in the alpine. More details and photos here.
Snowpack Summary
20-50 cm of new snow has fallen in the region since Thursday. The highest amounts fell near Revelstoke, and the amounts taper significantly south of Trout Lake. This new snow sits wind slab, surface hoar (feathery crystals), facets (sugary snow) and a crust on sun-exposed slopes. A persistent weak layer that was buried in mid January is now buried 35-85cm. This layer consists primarily of surface hoar, however there is also a crust associated with it on sun-exposed slopes. This layer has been most reactive at treeline and below.
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.
Persistent Slabs
Persistent Slab avalanches are the release of a cohesive layer of snow (a slab) in the middle to upper snowpack, when the bond to an underlying persistent weak layer breaks. Persistent layers include: surface hoar, depth hoar, near-surface facets, or faceted snow. Persistent weak layers can continue to produce avalanches for days, weeks or even months, making them especially dangerous and tricky. As additional snow and wind events build a thicker slab on top of the persistent weak layer, this avalanche problem may develop into a Deep Persistent Slab.