Avalanche Forecast
Issued: Feb 7th, 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 storm will intensify overnight and strong southwest wind combined with new snow will form fresh wind slabs in lee terrain features. Highest snowfall amounts of 20-30 cm are expected in the Coquihalla area.
Summary
Confidence
Moderate - Uncertainty is due to the timing, track, & intensity of the incoming weather system.
Weather Forecast
Friday Night: Snow, accumulation 5-15 cm with highest amounts of 20-30 cm in the Coquihalla area, strong southwest wind, alpine high -4 C, freezing level 1200 m.
Saturday: Mix of sun and cloud, moderate to strong north wind, alpine high -6 C, freezing level 900 m.
Sunday: Mix of sun and cloud, light to moderate northwest wind, alpine high -5 C, freezing level 1000 m.
Monday: Mostly sunny, light to moderate northwest wind, alpine high -4 C, freezing level 1500 m.
Avalanche Summary
No new avalanches were observed on Thursday.
On Wednesday numerous small (size 1) natural slab avalanches were observed below treeline which released within the recent storm snow and were very soft. Several small (size 1) and one large (size 2) loose dry avalanche were reported.Â
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 still concern for deep releases in that part of the region.
Snowpack Summary
The new snow sits on a variety of surfaces. 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 1900 m, snow overlies a crust.
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 newly formed and reactive wind slabs as you transition into wind affected terrain.
- Be alert to conditions that change with elevation and wind exposure.
- Carefully evaluate steep lines for wind slabs.
Problems
Storm Slabs
Strong southwest wind overnight combined with new snow will create fresh wind slabs in lee terrain features sensitive to human triggers. In the Coquihalla area where highest snowfall amounts of 20-30 cm are expected thick wind slabs will form. Be cautious when transitioning into wind affected terrain, especially when wind loaded slopes are exposed to the sun.
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 8th, 2020 5:00PM
