Avalanche Forecast
Issued: Dec 2nd, 2021 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.
Stephen Holeczi,
Cooler temperatures are on the way which should improve conditions slowly over the next few days. However, users can still trigger large, destructive avalanches. Mount Dennis avalanche closure zone in Yoho closed on Friday.
Summary
Weather Forecast
Thursday AM, alpine temperatures will decrease to -15C and valley bottom temperatures at -7 to -10C. Temperatures should stay below freezing, with moderate alpine winds diminishing over the day. No snow expected Thursday.
Snowpack Summary
Wednesday's storm started as rain to 2400m for most of the day, saturating the snowpack, and turned to snow early Thursday AM. Anywhere from 30-80+cm was deposited from this storm in the alpine with high settlement from warm temperatures. A midpack Nov.15 crust is found below 2100m, and the Nov. 5 crust/facet layer exists near the ground.
Avalanche Summary
Wednesday saw many natural avalanches to size 3.5, and Thursday produced sporadic results. Some targets produced minimal results, but some results were 40-100cm deep storm slabs, some stepping down to the basal crust/facets and entraining loose wet snow below treeline. A few crowns where it stepped down were 200cm deep.
Confidence
Problems
Storm Slabs
There has been an estimated 40 to 80+cm of new snow with strong winds from Wednesday's storm. Treeline slabs are softer due to lack of wind and have been more reactive to explosives, with more wind effect seen in the alpine.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Deep Persistent Slabs
Explosives produced slabs on the basal Nov 5 crust/facets. Some initiated on this layer, while others were "step down" avalanches. Cooling temperatures should decrease the likelihood over time, but there is uncertainty as to how long this will take.
- Be aware of the potential for full depth avalanches due to deeply buried weak layers.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Dec 3rd, 2021 4:00PM
