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Avalanche Forecast

Archived

Dec 3rd, 2018–Dec 4th, 2018

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

Regions

South Columbia.

There is a fair degree of uncertainty surrounding the snowpack. Check out the latest forecasters' blog here for more information and advice on managing current conditions.

Confidence

Moderate - Due to the number of field observations

Weather Forecast

MONDAY NIGHT - Cloudy with clear periods / light northwest winds / alpine low temperature near -12TUESDAY - A mix of sun and cloud / light to moderate west winds / alpine high temperature near -10WEDNESDAY - A mix of sun and cloud / light east to northeast winds / alpine high temperature near -9, low temperature near -12THURSDAY - Sunny with cloudy periods / light southerly winds / alpine high temperature near -5, low temperature near -10

Avalanche Summary

One size 1.5-2 skier triggered avalanche was reported to have run on the surface hoar layer at 2450 m on a northwest aspect.Several large, notable avalanches that were reported in the last 10 days in the region are listed below:On December 1 a natural size 3 slab avalanche was seen on Mt. Begbie (east to northeast aspect above 2000 m). It is likely that this avalanche was initiated by a large trigger such as a rock or cornice fall, and that it ran on the October crust.On November 29 an explosives triggered size 2.5 avalanche ran on the October crust on a north to northeast aspect at 2300 m.On November 24 a human triggered size 3 avalanche was reported in the region. This avalanche likely ran on the October crust, as it was reported as a full depth avalanche. Two reports on this avalanche can be found on the Mountain Information Network. MIN

Snowpack Summary

40-80 cm of recent snow sits on two layers of surface hoar (weak feathery crystals) that are buried approximately 15-20 cm apart. These layers have both been associated with a sun crust on steeper south facing slopes. The surface hoar is mostly found at treeline, but it may be found in sheltered alpine areas. At the base of the snowpack is a crust that formed near the end of October. This crust is associated with weak, faceted (sugary) snow and has shown some reactivity in the region. This layer is most prominent in the alpine but may exist into upper treeline elevations as well.Snowpack depths taper quickly with elevation, many areas have over 200 cm in the alpine, between 100-170 cm at treeline, and 10-100 cm below treeline.

Problems

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.

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.