Avalanche Forecast

Issued: Dec 20th, 2018 4:58PM

The alpine rating is considerable, the treeline rating is considerable, and the below treeline rating is considerable. Known problems include Storm Slabs and Persistent Slabs.

Avalanche Canada kdevine, Avalanche Canada

The storm and associated natural avalanches have tapered off to some degree, but give the snowpack some time to adjust to recent loading as the new sits on a weak layer that will likely need more time to gain strength.

Summary

Confidence

Moderate - Due to the number of field observations.

Weather Forecast

THURSDAY NIGHT: Cloudy with flurries, up to 10 cm, southwest winds, 60-90 km/h, alpine low temperature near -5°c, freezing level 2000m. FRIDAY: A mix of sun and cloud, west winds, 60-70 km/h, alpine high temperature near -7°c, freezing level 1200m and dropping to valley bottom by the evening. SATURDAY: Sunny with cloudy periods, southwest winds, 20-40 km/h, alpine high temperature near -5°c, low temperature near -8°c. SUNDAY: Cloudy with sunny periods and isolated flurries, southwest winds, 50-70 km/h, alpine high temperature near -5°c, low temperature near -8°c.

Avalanche Summary

One size 2 explosives triggered avalanche was reported on a north aspect at 1800 m on Thursday. No new natural avalanches were reported in the region. Numerous natural and explosives triggered avalanches to size 2.5 were reported in the region on Wednesday. Many of these were up to 100 cm deep. A notable avalanche on Wednesday was a size 3.5 explosives triggered avalanche in which the explosives were placed on a cornice. When the cornice failed, it triggered a 200 cm deep slab that failed on the crust at the base of the snowpack. This avalanche occurred on a northeast aspect at approximately 2000 m.

Snowpack Summary

50-80 cm of recent snow sits on a weak layer that formed in early December. This layer mostly consists of facets (sugary snow) with some isolated areas also containing small surface hoar (feathery crystals). Several other weak layers have been observed in the lower snowpack such as rain crusts and facets that formed in late October/early November.

Problems

Storm Slabs

An icon showing Storm Slabs
Recent storm slabs sit on a weak layer of facets (sugary snow)
Watch for whumpfing, hollow sounds, shooting cracks or recent avalanches.If triggered the storm slabs may step down to deeper layers resulting in large avalanches.Use conservative route selection, choose moderate angled and supported terrain with low consequence.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible

Expected Size

1 - 2

Persistent Slabs

An icon showing Persistent Slabs
A widespread weak layer near the base of the snowpack has the potential to produce large, destructive avalanches if triggered.
Avoid areas with overhead hazard.Remote triggering is a concern, watch out for adjacent slopes.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible

Expected Size

2 - 3

Valid until: Dec 21st, 2018 2:00PM