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 Storm Slabs and Deep Persistent Slabs.
jleblanc,
Avalanche Canada
Small avalanches may be common in steep and/or leeward terrain.
Large human-triggered deep persistent slab avalanches remain possible.
Keep avoiding steep, rocky, wind-affected terrain and choose small, low-consequence features.
Summary
Confidence
Moderate
Avalanche Summary
Several dry loose avalanches (size 1) were naturally triggered within the new storm snow on steep northerly alpine features near St.Mary's.
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.
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, 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. 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.
Saturday night
Cloudy. Isolated flurries. Low alpine temperatures of -8 °C. Light southwest ridge wind. Freezing level at valley bottom.
Sunday
Cloudy with sunny periods. Isolated flurries. High alpine temperatures of -3 °C. Light easterly ridge wind. Freezing level rises to 1400 metres.
Monday
Cloudy with sunny periods. Lingering flurries. High alpine temperatures of -5 °C. Light southwest ridge wind. Freezing level rises to 1400 metres.
Tuesday
A mix of sun and clouds. High alpine temperatures of -3 °C. Light easterly ridge wind. Freezing level rises to 1700 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
Recent snow may be bonding poorly to the underlying surfaces and still be reactive to human traffic, especially where it has been wind-affected. In sheltered terrain where the new snow has not been wind-affected, dry loose avalanches could initiate in steeper 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 26th, 2023 4:00PM
