Avalanche Forecast
Issued: Feb 22nd, 2022 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Wind Slabs and Persistent Slabs.
rbuhler,
Avalanche Canada
Recently formed wind slabs are expected to remain reactive to human-triggering in exposed high elevation terrain on Wednesday.
Summary
Confidence
Weather Forecast
High pressure remains the dominant feature for the rest of the week. However, a disturbance is expected to move through the region late Wednesday bringing increased cloud cover, shifting winds, and a chance of flurries.
Tuesday Night: Clear, light to moderate N wind, treeline low around -16 °C.
Wednesday: Mainly sunny with increasing cloud in the late afternoon, moderate to strong NW wind, treeline high around -8 °C.
Thursday: Mainly sunny, light N wind, treeline high around -3 °C.
Friday: Sunny, light SW wind, treeline high around -2 °C.
Avalanche Summary
On Monday, a natural size 2.5 cornice release was observed on a north aspect at 1900 m which pulled a small slab on the slope below. One natural size 1 wind slab was observed and skiers triggered several size 1 wind slabs. One of these was on a north aspect while the rest were on southeast through southwest aspects.
On Sunday, natural size 1 wind slabs were being observed as well as some isolated natural loose activity. A natural size 2 cornice was also reported which did not trigger a slab.
On Thursday, a natural icefall triggered a size 2.5 slab avalanche on the slope below. This avalanche was on a northeast aspect at 2100 m. Details were limited but we expect this may have been a persistent slab avalanche.
Snowpack Summary
The weekend storm produced 5-10 cm of snow with strong southwest wind that likely formed thin wind slabs in exposed terrain. On Monday, the wind switched to a northeast direction causing reverse loading and thin wind slabs may now exist on all aspects in exposed terrain.
The mid-February crust is down 10-30 cm. This melt-freeze crust is reported to exist on all aspects and elevations, except for some of the highest elevation polar aspects. Facets have been observed above the crust on polar aspects.
The late-January crust/facet/surface hoar interface is buried down 40-100 cm. This layer was most reactive between 1700 m and 2000 m. While this layer now appears to be dormant through most of the region, it may still be possible to trigger it at upper treeline or lower alpine features on polar aspects with a large load like a cornice or in shallow snowpack areas.
Terrain and Travel
- Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
- Closely monitor how the new snow is bonding to the crust.
- Be aware of the potential for large avalanches due to the presence of buried persistent weak layers.
Problems
Wind Slabs
Recent strong northly wind has formed thin wind slabs in exposed terrain at higher elevations.
Aspects: East, South East, South, South West, West.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Persistent Slabs
The late-January weak layer is down 40-100 cm and was most reactive between 1700 and 2000 m. It is now likely dormant in most areas. It is likely only possible to trigger on polar aspects at upper treeline or lower alpine where the mid-February crust is thinner and not bridging.
Aspects: North, North East, East, West, North West.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Feb 23rd, 2022 4:00PM
