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Avalanche Forecast

Archived

Dec 5th, 2018–Dec 6th, 2018

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.
Alpine
Natural avalanches unlikely, human triggered possible.
Treeline
Natural avalanches unlikely.
Below Treeline
Natural avalanches unlikely.

Regions

Purcells.

Field observations are limited in the Purcells, so it is important to supplement this forecast with your own observations. If you get out this week, tell us what you see by posting to the MIN! (here)

Confidence

Moderate - Due to the number of field observations

Weather Forecast

WEDNESDAY NIGHT - Cloudy with clear periods / light west wind / alpine low temperature near -12THURSDAY - A mix of sun and cloud / light southwest winds / alpine high temperature near -7FRIDAY - Sunny with cloudy periods / light southwest winds / alpine high temperature near -7, low temperature near -8SATURDAY - Cloudy with sunny periods / light southwest winds / alpine high temperature near -6, low temperature near -9

Avalanche Summary

Now new avalanches have been reported in the region.

Snowpack Summary

Approximately 20 cm of snow fell last week with minimal wind effect, however it may still be possible to find wind slabs on lee and cross loaded terrain features. There are two layers of surface hoar (weak feathery crystals) being reported in the top 15-30cm. The surface hoar is most prominent at treeline, but it may be found in sheltered alpine areas. Both of these layers may be associated with a sun crust on south aspects in some areas.Another notable feature in the snowpack is a combination of a crust and faceted (sugary) snow found at or near the base of the snowpack. This layer is most prominent in the alpine.The early season snowpack is highly variable in the Purcells. Total snowpack depths vary greatly throughout the region with anywhere between 70 and 150 cm in the alpine and tapering rapidly at treeline and below. In shallow snowpack areas, the bottom half of the snowpack is reportedly weak and "hollow" feeling on shady aspects due to sugary, faceted snow.

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.