Avalanche Forecast
Issued: Mar 25th, 2023 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Deep Persistent Slabs and Persistent Slabs.
jleblanc,
Avalanche Canada
Inherently weak and dangerous snowpack structure remains.
High-consequence human-triggered avalanches are possible.
Keep avoiding steep, rocky, wind-affected terrain and choose small, low-consequence features.
Summary
Confidence
Moderate
Avalanche Summary
Numerous natural dry loose avalanches (size 1) were observed within the recent snow on steep northerly alpine terrain in the south part of the region on Saturday.
Earlier in the week, strong solar radiation triggered several natural size 2 to 3 deep persistent slabs on south aspects, from rocky alpine and treeline features between 1900 and 2700 m. Additionally, a variety of solar-triggered loose wet avalanches up to size 2 were observed from steep, rocky slopes. A step-down avalanche, involving the mid-snowpack persistent weak layer, was also reported near Panorama Ski Resort on Wednesday. A remotely triggered persistent slab avalanche was reported last Sunday, failing down 70 cm on facets and triggered from 30 m away on a NW alpine slope.
While recent activity may seem to have tapered off, remote and step-down avalanches are a reminder that the layers are likely still reactive in some locations in the region, especially thin, rocky areas in the alpine.
Snowpack Summary
At upper elevations, a dusting of new snow overlies a crust on solar aspects, faceted snow and surface hoar (up to 10 mm) in shaded and wind-sheltered areas. Wind-affected surfaces is also found in exposed areas.
In the middle of the snowpack, there are at least a couple of lingering persistent weak layers, including surface hoar in wind-sheltered terrain and a sun crust on south aspects. Activity on these layers has tapered off but still remains a concern in isolated areas.
The lower snowpack is made up of a widespread layer of large, weak facets and/or depth hoar crystals. This weak layer has been responsible for a number of recent very large, destructive avalanches and will likely continue to be a concern for the rest of the season.
Weather Summary
Unsettled weather will continue to bring scattered flurries until a ridge of high pressure invades the region early next week.
Saturday night
Cloudy with isolated flurries. Low alpine temperatures of -9 °C. Light northwest ridge wind up to 25 km/h. Freezing level at valley bottom.
Sunday
Cloudy with sunny periods. Isolated flurries. High alpine temperatures of -6 °C. Light easterly ridge wind. Freezing level rises to 1500 metres.
Monday
Cloudy with sunny periods. Isolated flurries. High alpine temperatures of -8 °C. Light westerly ridge wind. Freezing level rises to 1200 metres.
Tuesday
A mix of sun and clouds. High alpine temperatures of -5 °C. Light easterly ridge wind. Freezing level rises to 1600 metres.
More details can be found in the Mountain Weather Forecast.
Terrain and Travel Advice
- Be mindful that deep instabilities are still present and have produced recent large avalanches.
- Avoid rock outcroppings, convexities, and anywhere the snowpack is thin and/or variable.
- Minimize your exposure time below cornices.
Problems
Deep Persistent Slabs
The base of the snowpack remains very weak. Very large human-triggered avalanches are possible at treeline and above. Avoid thin, rocky start zones and shallow areas with variable snowpack depth where you are most likely to trigger this layer. Give careful consideration to the slopes overhead as large avalanches may run well into the runout zone or into lower-angle terrain.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Persistent Slabs
Lingering weak layers are present at all elevations and on various aspects. On shaded slopes, these layers generally present as surface hoar or facets, while on sun-exposed slopes, they appear as facets and a crust.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Mar 26th, 2023 4:00PM
