Avalanche Forecast
Issued: Mar 29th, 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
Be aware of loose avalanches stepping down into persistent weak layers and creating large releases. Shallow rocky areas should still be considered suspect.
Summary
Confidence
Avalanche Summary
Several wet loose avalanches (up to size 2) occurred Tuesday and Wednesday on south aspects throughout the region, as conditions were clear and sunny.
While activity may have started to taper off on the deeper layers, some locations in the region (especially thin, rocky areas in the alpine) are still of concern.
Snowpack Summary
In localized areas at upper elevations, convective flurries generated up to 15-20 cm of recent snow Monday. Dry snow still exists at upper elevations on true north aspects, while moist snow is present at most elevations. This 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 are 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 comprises a widespread layer of large, weak facets and/or depth hoar crystals. This weak layer has been responsible for a number of very large, destructive avalanches last week and will likely continue to be a concern for the rest of the season. Professionals are still tracking it to watch for signs of it waking up.
Weather Summary
The region will be under a building ridge of high pressure, with calm and dry conditions until Friday, when a southwesterly flow will return.
Wednesday night
Clear with cloudy periods. Low alpine temperatures of -10 °C. Light easterly ridge wind. Freezing level at valley bottom.
Thursday
A mix of sun and clouds. High alpine temperatures of -3 °C. Light easterly ridge wind. Freezing level rises to 2000 metres.
Friday
Cloudy with sunny periods. Isolated flurries. High alpine temperatures of -5 °C. Light southerly ridge wind gusting 40 km/h. Freezing level rises to 1500 metres.
Saturday
Cloudy with sunny periods. Isolated flurries. Local amounts up to 5 cm. High alpine temperatures of -5°C. Light southwesterly ridge wind gusting 40 km/h. Freezing level rises to 1500 metres.
More details can be found in the Mountain Weather Forecast.
Terrain and Travel Advice
- Avoid exposure to overhead avalanche terrain as temperatures increase.
- If triggered loose wet avalanches may step down to deeper layers resulting in larger 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. Uncertainty remains about the effect of solar radiation on this layer.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Mar 30th, 2023 4:00PM
