Avalanche Forecast
Regions: Little Yoho.
Potential still exists for human triggering of large avalanches. Manage overhead exposure carefully and make careful terrain choices at all elevations. We are back to a more typical Rockies snowpack and the weaknesses will be present for some time.
Weather Forecast
Continued cool alpine temperatures (-12 to -18'C) through Wednesday with light West winds and very light flurries.
Snowpack Summary
Wind slabs in alpine and treeline areas. 40-70cm of snow sits over the Jan 6 surface hoar/facet layer and remains reactive to skier triggering. Test results show sudden collapse results on this layer and we have experienced many large whumphs over the last few days, with failures on both the Jan 6 layer, and in the mid pack facets below this layer.
Avalanche Summary
Visitor Safety was able to trigger a size 1.5 wind slab on a SE steep alpine feature on Monday near Observation Peak. A large natural cornice collapse also occurred Monday in the Sunshine backcountry on Quartz Ridge. Lots of evidence of the previous widespread natural avalanche cycle up to size 3 on all aspects with some very large propagations.
Confidence
Avalanche Problems
Wind Slabs
Recent wind has built soft slabs 30 to 50cm deep in alpine and treeline lee areas, and established new growth on cornices. Although these slabs are slowly becoming more difficult to trigger, human triggering is still possible.
- If triggered the wind slabs may step down to deeper layers resulting in large avalanches.
- Avoid steep lee and cross-loaded features
Aspects: North, North East, East, South East.
Elevations: Alpine, Treeline.
Likelihood: Possible
Expected Size: 1 - 2
Persistent Slabs
30-70 cm of snow overlies the Jan 6 layer of surface hoar and facets. Test results on this layer show it is still in the range of human triggering with potential for failures to step down into deeper layers and result in large avalanches.
- Use careful route-finding and stick to moderate slope angles with low consequences
- Avoid open slopes and convex rolls where buried surface hoar may be preserved.
Aspects: All aspects.
Elevations: All elevations.
Likelihood: Possible - Likely
Expected Size: 2 - 3