Avalanche Forecast
Issued: Jan 7th, 2021 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Wind Slabs, Persistent Slabs and Deep Persistent Slabs.
Garth Lemke,
Winds have diminished except for the very high alpine but the wind-slabs have formed from previous days. Natural avalanche activity has decreased yet conservative terrain selection is advised, assess every slope and human triggering remains possible.
Summary
Weather Forecast
Friday will be sun and cloud, flurries, -8C, and Light SW winds. Saturday will be similar, no new snow, -13C and light SW winds. Freezing level at valley bottom. Sunday will be clouds, sun, flurries, -12C, and light SW winds. There is no significant snow on the horizon.
Snowpack Summary
40cm of new snow from Jan 3rd continues to be redistributed by SW winds into wind-slabs mainly at exposed ridge-tops. This new snow overlies a sporadically distributed surface hoar and facet layer down 40-70cm. The mid-pack is supportive except in shallow locations. The bottom is weak facets and depth hoar.
Avalanche Summary
Thursday's patrol to the Icefield's noted one size 3, N-NE aspect, very high alpine, 1m thick and 300m wide on the backside of Mushroom peak. It is likely a very wind-loaded location. No patrol occurred on Wednesday. Tuesday's Hilda patrol had no new. Sunday's explosive control had varied results with some size 3's Use Mountain Information Network.
Confidence
Due to the number and quality of field observations
Problems
Wind Slabs
Periodic SW winds continue to form wind slabs treeline and above. They appear to be stubborn with no natural activity observed the past 3 days but be vigilant for human triggering to remain possible.
- Use caution in lee areas. Recent wind loading has created reactive slabs.
- If triggered the storm/wind slabs may step down to deeper layers resulting in large avalanches.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Persistent Slabs
Use caution around thin to thick areas where buried deeper weak layers could be triggered. The surface hoar layer down 40-60cm seems unreactive and spotty distribution but keep it on your radar.
- Dig down to find and test weak layers before committing to a line.
Aspects: All aspects.
Elevations: Treeline, Below Treeline.
Likelihood
Expected Size
Deep Persistent Slabs
When the snowpack is thick, this weakness should be well bridged and less susceptible to triggering. Triggering this deep layer would be low probability but high consequence.
- Avoid thin, rocky or unsupported slopes.
- Pay attention to overhead hazards like cornices which could easily trigger the deep persistent slab.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Valid until: Jan 8th, 2021 4:00PM
