Avalanche Forecast
Issued: Feb 1st, 2020 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Storm Slabs and Deep Persistent Slabs.
ahanna,
Avalanche Canada
If you choose to tiptoe out into the mountains this weekend, stick to conservative, low consequence terrain and avoid overhead hazard.
Summary
Confidence
Moderate - Recent weather patterns have resulted in a high degree of snowpack variability within the region. Uncertainty is due to the fact that deep persistent slabs are particularly difficult to forecast.
Weather Forecast
Saturday night: Partly cloudy. Moderate southwest wind. Freezing level valley bottom.
Sunday: Mix of sun and cloud with isolated flurries. Moderate southwest wind. Alpine high -8 C. Freezing level valley bottom.
Monday: Mix of sun and cloud. Light northwest wind. Alpine high -8 C. Freezing level valley bottom.
Tuesday: Mostly cloudy with flurries. Moderate west wind. Alpine high -6 C. Freezing level valley bottom.
Avalanche Summary
A natural storm slab cycle up to size 2.5 was observed Friday night along the Duffey Lake road corridor. Avalanche results from explosive control work is suspected to have run on the deep persistent crust.
Reports of very large (size 3) deep persistent avalanches have been steadily coming in over the past week from the north half of the region. The most recent events occurred on Monday near Goldbridge, Whitecap and Duffey Lake. While most of these events have been naturals on north to east aspects in the alpine, some have been remotely triggered by skiers.
Snowpack Summary
Recent snow continues to be loaded into lee features in the alpine by moderate southwest wind. Above 1800 m, storm totals for the north of the region are in the range of 30-50 cm, while the Coquihalla received around 100 cm and the Manning Park area received around 35 cm. Below 1800 m, snow overlies a crust and tapers with elevation.
In the north half of the region (ie. Goldbridge/Whitecap/Duffey/Hurley), a few deep instabilities exist in the snowpack, including a weak basal facet crust complex. This has been the failure plane in ongoing reports of deep persistent avalanches. The significant new loads from snowfall and rain will stress the deep basal weakness.
The south of the region, including the Coquihalla and Manning areas, currently have no concerns about deep instabilities.
Terrain and Travel
- Make conservative terrain choices and avoid overhead hazard.
- Be alert to conditions that change with elevation.
- Avoid freshly wind loaded terrain features.
- Be aware of the potential for surprisingly large avalanches due to deeply buried weak layers.
- Brief periods of sun could quickly initiate natural avalanche activity.
Problems
Storm Slabs
Storm slab avalanches up to size 2.5 have been observed since the storm. Storm slabs will remain especially sensitive where the wind continues to deposit recent snow into deeply loaded pockets in lee features.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Deep Persistent Slabs
Significant loading from recent snow, rain and ongoing wind weigh heavily on deep weaknesses near the bottom of the snowpack. Failure of these weak layers has produced very large, destructive avalanches. These layers do not pose an avalanche problem in the south half of the region.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Feb 2nd, 2020 5:00PM
