Avalanche Forecast
Issued: Mar 28th, 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
Direct sun and rising freezing levels could weaken the snowpack on southerly aspects.
Wet loose avalanches may step-down into persistent weak layers and create large releases.
Approach shallow rocky areas with caution.
Summary
Confidence
Avalanche Summary
We suspect that wet loose avalanches occurred Tuesday on south aspects throughout the region, as conditions were clear and sunny.
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 the weekend.
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. This unconsolidated 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 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. 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 for the next few days.
Tuesday night
Clear with cloudy periods. Low alpine temperatures of -9 °C. Light easterly ridge wind. Freezing level at valley bottom.
Wednesday
Generally sunny. High alpine temperatures of -2 °C. Light easterly ridge wind. Freezing level rises to 2000 metres.
Thursday
Increasing cloudiness. 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 -3 °C. Light westerly ridge wind. Freezing level rises to 2000 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 29th, 2023 4:00PM
