Natural avalanches unlikely, human triggered possible.
Treeline
Natural avalanches unlikely.
Below Treeline
Natural avalanches unlikely.
Alpine
Natural avalanches unlikely, human triggered possible.
Treeline
Natural avalanches unlikely.
Below Treeline
Natural avalanches unlikely.
Alpine
Natural avalanches unlikely, human triggered possible.
Treeline
Natural avalanches unlikely.
Below Treeline
Natural avalanches unlikely.
Regions
Banff Yoho Kootenay.
A large avalanche (skier remote) was triggered on Mt. Whymper yesterday. This was regarded as an anomaly. Deep persistent slab avalanches are still possible. Continue to make judicious terrain choices as the spring conditions set in.
Weather Forecast
Cloudy skies and light precip is forecasted for the region. Generally, there will not be enough accumulation to alter the danger rating. The first increase in temperature is forecasted on Saturday. If this comes to fruition, expect a major cycle with large avalanches running on the basal facets.
Snowpack Summary
A supportive melt-freeze crust exists on all aspects to 1900m and higher on south and west aspects. Dry snow exists on N/NE aspects above this. The snowpack is well settled with no surface instabilities. The deep persistent weak layers are dormant, but may awaken if it warms up. As demonstrated yesterday on Mt. Whymper, (see avalanche table).
Avalanche Summary
Forecasters were very surprised yesterday after hearing a report of a size 3.5 skier remote avalanche on Mt. Whymper. The group heard a whumph and 30 seconds later the slide released taking out the whole slope the party had just climbed up from 70m away. Dimensions: 400m wide x 100cm deep x 1000m long. Reminder, nothing is certain. Picture
Confidence
Problems
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.
Loose Wet
Loose Wet avalanches are the release of wet unconsolidated snow or slush. These avalanches typically occur within layers of wet snow near the surface of the snowpack, but they may quickly gouge into lower snowpack layers. Like Loose Dry Avalanches, they start at a point and entrain snow as they move downhill, forming a fan-shaped avalanche. Other names for loose-wet avalanches include point-release avalanches or sluffs. Loose Wet avalanches can trigger slab avalanches that break into deeper snow layers.