Avalanche Forecast
Issued: Dec 24th, 2020 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Wind Slabs and Persistent Slabs.
swerner,
Avalanche Canada
Warming temperatures and sunshine may be enough to stiffen the slab and increase the reactivity for natural and human triggered avalanches. Loose dry avalanches from steep terrain may also occur and run far and fast downslope.
Summary
Confidence
Moderate - Uncertainty is due to the extreme variability of wind effect on the snowpack.
Weather Forecast
Friday: Mix of sun and cloud. Alpine temperatures near -1 and freezing levels 1700 m. Ridgetop wind moderate to strong from the southwest.
Saturday: Mix of sun and cloud with a trace of new snow. Alpine temperatures near -5 and freezing levels valley bottom.Â
Sunday: Cloudy with isolated flurries. Alpine temperatures near -6 and freezing levels 1100 m and dropping to valley bottom overnight.Â
Avalanche Summary
No new reports on Thursday at the time of publishing.
Numerous natural wind slab avalanches up to size 2 were reported today from our field team. These were mostly seen from West aspects in the alpine.Â
On Tuesday widespread natural avalanche activity up to size 3 was reported through the region.
Natural avalanche activity may taper off a bit but the snowpack remains primed for human triggering.Â
Please consider sharing your observations on the Mountain Information Network. Thank you to those that have already submitted this winter!
Snowpack Summary
30-50 cm of recent storm snow blanketed the region by Tuesday morning. Recent strong to extreme southwest wind has redistributed some of this new snow building touchy wind slabs on leeward slopes. A persistent slab 70-100 cm thick now sits on the early December crust. This persistent weak layer, with facetted crystals and surface hoar crystals above and/or below it may be reaching a tipping point. Smaller avalanches may step-down to this weak layer.Â
The base of the snowpack consists of a hard melt-freeze crust from early-November that may also have weak crystals around it. This potential avalanche problem is dormant at this time, however; it remains on our radar. The most likely spot to trigger it would be on thin and rocky slopes or, like above, from step down avalanches in the recent storm snow.
Terrain and Travel
- Shooting cracks, whumphs and recent avalanches are strong indicators of an unstable snowpack.
- If triggered, wind slabs avalanches may step down to deeper layers resulting in larger avalanches.
- Uncertainty is best managed through conservative terrain choices at this time.
Problems
Wind Slabs
Wind slabs are likley reactive on most aspects due to strong, changing winds and a lot of available snow to transport. Natural avalanches, whumphing, and shooting cracks in the snow are all indicators of a instability. Loose-dry sluffing from steep terrain is likely, especially when the sun comes out.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Persistent Slabs
70-100 cm of snow currently sits above a weak layer from early December. Combinations of sugary facets , surface hoar and/or a crust mean persistent slabs are likely reactive, especially to human triggers.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Valid until: Dec 25th, 2020 4:00PM
