Avalanche Forecast
Issued: Mar 26th, 2023 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Loose Dry and Deep Persistent Slabs.
jleblanc,
Avalanche Canada
Convective snowfalls could bring localized heavy precipitation, especially in higher terrain.
Uncertainty remains about the total accumulation from these enhanced precipitations.
This new snow will likely bond poorly to the underlying surfaces and be reactive to riders.
Summary
Confidence
Avalanche Summary
Several dry loose avalanches (size 1) were naturally triggered within the recent snow on steep northerly alpine features near St.Mary's on Saturday.
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.
Last 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, 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.
Snowpack Summary
At upper elevations, up to 15 cm of recent snow overlies a crust on solar aspects, faceted snow and surface hoar up in shaded and wind-sheltered areas. Wind-affected surfaces are found 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
Unsettled weather will continue to bring scattered flurries until a ridge of high pressure invades the region early next week. Enhanced precipitations are expected in higher terrain Sunday night and Monday.
Sunday night
Cloudy. Isolated flurries. Local amounts of 5-10 cm and up to 15 cm in higher ground. Low alpine temperatures of -7 °C. Light southeasterly ridge wind. Freezing level at valley bottom.
Monday
Cloudy with sunny periods. Lingering flurries. High alpine temperatures of -5 °C. Light southwest ridge wind. Freezing level rises to 1500 metres.
Tuesday
A mix of sun and clouds. High alpine temperatures of -3 °C. Light easterly ridge wind. Freezing level rises to 1500 metres.
Wednesday
A mix of sun and clouds. High alpine temperatures of -2 °C. Light easterly ridge wind. Freezing level rises to 1800 metres.
More details can be found in the Mountain Weather Forecast.
Terrain and Travel Advice
- Loose avalanches may start small but they can grow and push you into dangerous terrain.
- 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
Loose Dry
Recent snow may bond poorly to the underlying surfaces and still be reactive to human traffic. In sheltered terrain where the new snow has not been wind-affected, fast dry loose avalanches could initiate in steeper terrain. Be careful with sluffing in steep terrain, especially above cliffs and terrain traps.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Deep Persistent Slabs
The base of the snowpack remains very weak and avalanches are unpredictable. 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 27th, 2023 4:00PM
