The unusual danger rating is due to a buried weak layer that exists mainly at treeline and below. It is easily triggered by humans and there is the potential for large avalanches at lower elevations. Choose low angled terrain, especially in the trees
Summary
Confidence
High -
Weather Forecast
TUESDAY NIGHT - Clear with cloudy periods / northeast winds 10-15 km/h / alpine low temperature near -20WEDNESDAY - Mainly sunny / northwest winds 10-15 km/h / alpine high temperature near -17THURSDAY - Cloudy sunny periods and isolated flurries, 2-4 cm / southwest winds 10-20 km/h / alpine high temperature near -15FRIDAY - Mainly cloudy with scattered flurries / east winds, 10-15 km/h / alpine high temperature near -15
Avalanche Summary
Natural avalanche activity began to slow down on Sunday, but a persistent weak layer that was buried in mid January continues to be reactive to human triggers. This layer is sensitive enough for humans to trigger avalanches remotely (from a distance). Human triggered avalanches up to size 2 were reported on Sunday and Monday.This
MIN report from Sunday illustrates the potential for humans to remotely trigger the mid January layer.Widespread avalanche activity was reported on Friday and Saturday. Numerous natural avalanches to size 3.5, explosives triggered avalanches to size 2.5, and human triggered avalanches to size 1.5 were reported. Many of these avalanches were triggered remotely (from a distance) and failed on the mid January layer. A few of the recent explosives triggered avalanches stepped down to ground.There is a great MIN report from January 22nd that shows a natural avalanche (size 3.5) in International Basin, on the deep persistent layer. Check it out
here. While this is an old observation, it is relevant as this layer is still lurking, and may catch people off guard.
Snowpack Summary
Approximately 30-60 cm of recent new snow sits on wind slab, surface hoar (feathery crystals), facets (sugary snow) and a crust on sun-exposed slopes. A very notable feature in the snowpack at this time is a persistent weak layer that was buried in mid January, which is now buried 50-90 cm. 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.The base of the snowpack has a deep persistent weak layer near the ground. This layer consists of facets over a crust. This weak interface continues to produce large and destructive avalanches that are sporadic in nature, and very difficult to predict. This layer is most likely to be triggered from areas where the snowpack is shallow and weak. Rocky alpine bowls, ridge crests and rocky outcroppings are some examples of the kind of terrain to be wary of.
kdevine,
Avalanche Canada
