Avalanche Forecast
Issued: Mar 24th, 2023 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.
zryan,
Avalanche Canada
New snow is expected to bond poorly to the underlying surface, small but reactive storm slab or dry loose avalanches may be common in steeper terrain.
Large human-triggered deep persistent slab avalanches remain possible. Stay diligent in your terrain selection by avoiding steep, rocky, wind-affected terrain and choosing small, low-consequence features.
Summary
Confidence
Avalanche Summary
On Wednesday, a very large natural deep persistent was observed north of Elkford. This avalanche occurred on a southwest aspect in the alpine, likely as a result of strong solar radiation. It ran to valley bottom and took out the Smith Basin trail. Full MIN report here.
On Monday, a natural cornice failure resulted in a size 1 avalanche in the St Mary's area east of Kaslo. The cornice dropped onto a steep slope and gouged down to the weak facets at the base of the snowpack.
While activity may have started to taper off on the deeper layers in this region, nearby avalanches are a reminder that the layers are likely still reactive in some locations in the region, especially thin, rocky areas in the alpine.
If you have any observations from this data sparse region, let us know what you are seeing by submitting a report to the Mountain Information Network.
Snowpack Summary
At upper elevations, up to 15 cm of new snow overlies a crust on solar aspects, faceted snow and surface hoar up in shaded and wind-sheltered areas, and wind-affected surfaces in exposed areas. At lower elevations, a crust exists on or near the surface.
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. These layers appear to have generally gone dormant but could still be reactive in isolated areas and should be on your radar in the Purcells part of the region.
The lower snowpack is made up of a widespread layer of large, weak basal facets and depth hoar in some areas. This weakness has been responsible for a number of recent very large, destructive avalanches and will continue to be a concern.
Weather Summary
Friday night
Clear periods. Alpine temperatures drop to a low of -8 °C. Ridge wind 10 to 35 km/h from the southwest. Freezing level at valley bottom.
Saturday
Cloudy with sunny periods. Alpine temperatures reach a high of -5 °C. Ridge wind light from the southwest. Freezing level rises to 1500 metres.
Sunday
Cloudy with sunny periods and isolated flurries. Alpine temperatures reach a high of -3 °C. Ridge wind light from the east. Freezing level rises to 1600 metres.
Monday
Cloudy with sunny periods and isolated flurries. Alpine temperatures reach a high of -5 °C. Ridge wind light from the southwest. Freezing level rises to 1400 metres.
More details can be found in the Mountain Weather Forecast.
Terrain and Travel Advice
- Look for signs of instability: whumphing, hollow sounds, shooting cracks, and recent avalanches.
- It's critical to stay disciplined and choose only well supported, low consequence lines.
- Avoid rock outcroppings, convexities, and anywhere the snowpack is thin and/or variable.
- Minimize your exposure time below cornices.
Problems
Storm Slabs
New snow is expected to bond poorly to the underlying surface, creating small but reactive storm slab or dry loose avalanches in steep terrain.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
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 depths where you are most likely to trigger this layer.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Mar 25th, 2023 4:00PM
