Avalanche Forecast
Issued: Mar 27th, 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 mindful that persistent instabilities are highly unpredictable and are still a concern.
It requires a patient and diligent mindset to keep avoiding steep, rocky, wind-affected terrain.
Summary
Confidence
Avalanche Summary
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.
The latest natural occurrences, including a step-down avalanche, in the mid-snowpack persistent weak layer, a remotely triggered avalanche and some very large natural deep release (size 2.5 to 3) happened about a week ago.
While recent activity may seem to have tapered off, remote and step-down 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 10 cm of recent 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.
Weather Summary
Unsettled weather will continue to bring scattered flurries Monday night. The region will be under a building ridge of high pressure, with calm and dry conditions for most of the week.
Monday night
Cloudy. Isolated flurries. Trace accumulation. Low alpine temperatures of -6 °C. Light westerly ridge wind. Freezing level at valley bottom.
Tuesday
A mix of sun and clouds. High alpine temperatures of -5 °C. Light easterly ridge wind. Freezing level rises to 1400 metres.
Wednesday
Sunny with cloudy periods. High alpine temperatures of -2 °C. Light easterly ridge wind. Freezing level rises to 2000 metres.
Thursday
Cloudy with sunny periods. High alpine temperatures of -3 °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
- Avoid rock outcroppings, convexities, and anywhere the snowpack is thin and/or variable.
- Conditions may have improved, but be mindful that deep instabilities are still present.
- Be mindful that deep instabilities are still present and have produced recent large avalanches.
- 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.
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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.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Mar 28th, 2023 4:00PM
