Avalanche Forecast
Issued: Nov 26th, 2020 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Storm Slabs.
shorton,
Avalanche Canada
Weather trends suggest avalanches are less likely on Friday, however be prepared to back away from steep slopes if there are signs of lingering storm or wind slabs.
Summary
Confidence
Weather Forecast
Clearing and cooling until the next storm arrives on Sunday.
THURSDAY NIGHT: Clearing skies, light wind from the west, freezing level drops to valley bottom with alpine temperatures dropping to -6 C.
FRIDAY: Mix of sun and cloud, light wind from the west, alpine high temperatures around -4 C.
SATURDAY: Light flurries with roughly 5 cm of snow, 40-60 km/h wind from the southwest, alpine temperatures around -3 C.
SUNDAY: Frontal system arrives with 15-35 cm of snow by the end of the day, strong to extreme wind from the south, freezing level climbing to 1000 m.
Avalanche Summary
Limited reports during the past few days of stormy weather suggest there have been a few natural cycles of size 1-2 storm slab avalanches in alpine terrain and some smaller wet loose avalanches at lower elevations. As the storm clears triggering storm slab avalanches remains a concern on steep terrain at higher elevations.
On Tuesday, a large (size 2.5) avalanche was triggered with explosives in the northern part of the region. This avalanche failed on weak snow around the crust at the bottom of the snowpack, which is a layer worth monitoring as the season progresses.
Snowpack Summary
Active weather over the past few days has delivered 30 to 50 cm of new snow, strong southwest wind, and temperatures spiking and then dropping. Our current assessment of the upper snowpack is largely based on automated weather stations, so it's worth inspecting the impact of these storms in your local area. Most likely the snow is settling rapidly and strengthening, but at higher elevations it's possible that cooler temperatures and strong wind has left unstable storm slabs.
The total snowpack depth is about 100 to 150 cm at upper treeline and alpine elevations, with significantly less at lower elevations. Early season reports suggest there was a thin weak layer of surface hoar roughly 30 to 60 cm below the surface that resulted in a few small avalanches a week ago, but this layer has likely gained strength since then. The bottom of the snowpack consists of several thick crusts. There could be weak snow developing around this crust in colder inland parts of the region.
Terrain and Travel
- Don't be too cavalier with decision making, storm slabs may remain sensitive to human triggering.
- Avoid areas where the snow feels stiff and/or slabby.
- Be alert to conditions that change with elevation and wind exposure.
Problems
Storm Slabs
Since Monday 30-50 cm of snow has fallen with several bouts of strong wind. This snow is likely gaining strength, but there is a fair bit of uncertainty about whether it may still be reactive at higher elevations and in wind-affected terrain.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Nov 27th, 2020 4:00PM
