Avalanche Forecast
Issued: Mar 15th, 2023 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Wind Slabs and Deep Persistent Slabs.
lbaker,
Avalanche Canada
Hazard will rise to considerable in the alpine during peak daytime heating.
Avoid thin areas like rock outcroppings where you are most likely to trigger deep persistent layers.
Summary
Confidence
Avalanche Summary
On Wednesday, a skier accidental size 2 wind slab avalanche was triggered near St. Mary's. The avalanche occurred on a northeast aspect at treeline and stepped down to the basal facets. For photos and more details check out the MIN.
On Tuesday, several natural size 2 wind slab avalanches were observed throughout the region at alpine and treeline. A size three natural avalanche was reported north of Sparwood. The start zone of the avalanche was a steep, rocky, cross-loaded alpine feature. It is suspected to have been a deep persistent slab avalanche.
If you head out in the backcountry, let us know what you are seeing by submitting a report to the Mountain Information Network.
Snowpack Summary
20-40 cm of wind-affected storm snow is found above 1400 m. The storm snow sits on a thin sun crust on solar slopes and wind affected snow in open areas. Below 1400 m a rain crust covers the surface.
In the Purcells, several weak layers from Jan and Feb can be found down 50 to 120 cm however they are showing signs of strengthening. The mid-snowpack is generally well-settled.
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
Wednesday Night
Few clouds clear through the night. Chance of isolated flurries, trace accumulation. Alpine temperatures reach a low of -8 °C. Ridge wind 10 km/h gusting to 30 km/h from the northwest. Freezing levels drop to valley bottom.
Thursday
Mainly sunny with scattered clouds in the afternoon. Alpine temperatures reach a high of -4 °C. Ridge wind west 10 km/h. Freezing levels rise to 1700 meters.
Friday
Mainly sunny. Alpine temperatures reach a high of -2 °C. Ridge wind southwest 15 km/h. Freezing levels rise to 1800 meters.
Saturday
Sunny. Alpine temperatures reach a high of 0 °C. Ridge wind southwest 20 km/h. Freezing levels rise to 2000 meters.
More details can be found in the Mountain Weather Forecast.
Terrain and Travel Advice
- Expect slab conditions to change drastically as you move into wind exposed terrain.
- Seek out sheltered terrain where new snow hasn't been wind-affected.
- Use caution on large alpine slopes, especially around thin areas that may propagate to deeper instabilities.
- Avoid rock outcroppings, convexities, and anywhere the snowpack is thin and/or variable.
Problems
Wind Slabs
Strong southwest winds and 20-40 cm of dense storm snow have built wind slabs in alpine and treeline lees. Although natural avalanche activity has tapered off wind slabs remain possible to human trigger.
If triggered, wind slab avalanches may step down to deeper weak layers resulting in large avalanches.
Aspects: North, North East, East, South East, North West.
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 shallow and rocky areas, where the snowpack depth is highly variable. This is a very concerning avalanche problem and should stay in your mind when traveling in the backcountry.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Mar 16th, 2023 4:00PM
