Avalanche Forecast

Issued: Dec 21st, 2018 4:43PM

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

Avalanche Canada kdevine, Avalanche Canada

Avalanche activity has slowed down, but the snowpack remains generally weak. Choose conservative terrain and pay close attention to signs of instability such as whumphing and cracking in the snow.

Summary

Confidence

Moderate - Due to the number of field observations.

Weather Forecast

FRIDAY NIGHT - cloudy with clear periods / west winds, 30-40 km/h / alpine low temperature near -12°c. SATURDAY - Cloudy with sunny periods / southwest winds, 15-35 km/h / alpine high temperature near -9°c. SUNDAY - Cloudy with isolated flurries / southwest winds, 40-60 km/h / alpine high temperature near -7°c,  low temperature near -9°c. MONDAY - Cloudy with isolated  flurries / light southwest winds / alpine high temperature near -5°c, low temperature near -7°c.

Avalanche Summary

Several natural and explosives triggered avalanches to size 2 were reported in the region on Friday. One size 2 explosives triggered avalanche was reported on a north aspect at 1800 m on Thursday. 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

60-90 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). Avalanche activity on this layer has slowed down, but in certain terrain features, it is likely that it would still be possible for humans to trigger avalanches on this layer. Features where the underlying ground surface is smooth, and areas where the snowpack varies from thin to thick would be the most likely places for humans to trigger an avalanche on this layer. 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)
Use conservative route selection, choose moderate angled and supported terrain with low consequence.If triggered the storm slabs may step down to deeper layers resulting in large avalanches.Watch for whumpfing, hollow sounds, shooting cracks or recent avalanches.

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.
Remote triggering is a concern, watch out for adjacent slopes.Avoid areas with overhead hazard.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible

Expected Size

2 - 3

Valid until: Dec 22nd, 2018 2:00PM