Avalanche Forecast
Issued: Feb 5th, 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.
ldreier,
Avalanche Canada
The danger rating is based on the forecast snowfall amounts for the south of the region where 20-35 cm of snow are expected by Thursday evening. Be careful when transitioning into wind affected terrain. Fresh wind slabs will be sensitive to human triggering.
Summary
Confidence
Low - Uncertainty is due to difficult to forecast freezing levels. Forecast precipitation (either snow or rain) amounts are uncertain.
Weather Forecast
Wednesday Night: Snow, flurries in the north of the region and accumulation 10-15 cm in the south, moderate to strong northwest wind, alpine high -5 C. Freezing level 1200 m.
Thursday: Snow, accumulation 5-10 cm in the north of the region and 10-20 cm in the south, moderate to strong northwest wind, alpine high -2 C, freezing level 800 m in the north of the region and 1500 m in the south.
Friday: Flurries, accumulation 5 cm in most parts of the region and 20 cm in the very south, moderate west wind, alpine high -4 C, freezing level 800 m in the north of the region and 1500 m in the south.
Saturday: Mix of sun and cloud, snow, accumulation up to 10 cm, moderate west wind, alpine high -4 C, freezing level 900 m.
Avalanche Summary
There have been no recent reports of avalanche activity. The deep persistent slab avalanche activity observed during last weekend's storm in the northern portion of the region seems to have tapered off. Although the likelihood of triggering has reduced there is is still concern for deep releases in that part of the region.
Snowpack Summary
New snow develops fresh wind slabs in the alpine and covers recent wind slabs. Extreme southwest wind during the storm last weekend has scoured windward aspects, formed deep loaded pockets in alpine lees and contributed to rapid cornice growth. Below 1800 m, snow overlies a crust and tapers with elevation.
In the north part of the region (ie. Goldbridge/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 very large, deep persistent avalanches.
The south of the region, including the Coquihalla and Manning areas, currently have no concerns about deeply buried weak layers.
Terrain and Travel
- Watch for avalanche hazard to increase throughout the day.
- Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
- A moist or wet snow surface, pinwheeling and natural avalanches are all indicators of a weakening snowpack.
- Use extra caution around cornices: they are large, fragile, and can trigger slabs on slopes below.
Problems
Storm Slabs
The south of the region is forecast to receive 20-35 cm of snow by Thursday evening whereas up to 10 cm of snow are expected in the north. The new snow will be redistributed by moderate to strong northwest wind and create sensitive wind slabs in lee terrain features in the alpine and at treeline.
In the south of the region the precipitation will fall in form of rain below around 1000 m and might form loose wet avalanches.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Deep Persistent Slabs
Although the likelihood of triggering a deep persistent slab avalanche has reduced, doing so would result in a large and destructive avalanche. 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 6th, 2020 5:00PM
