Avalanche Forecast
Issued: Mar 14th, 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.
lbaker,
Avalanche Canada
Storm snow and strong southwest winds have created dangerous avalanche conditions in the alpine. Use extra caution when transitioning into wind affected terrain, where storm slabs remain reactive to human triggering.
Avoid thin, rocky, wind effected areas where triggering slabs is more likely. If triggered storm slabs may step down to deep weak layers resulting in large destructive avalanches.
Summary
Confidence
High
Avalanche Summary
On Monday, a few 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
The Purcells received 30-40 cm of storm snow while the Rockies received 10-15 cm of storm snow over the last few days. Storm snow covers a variety of surfaces including hard wind-affected surfaces in open areas, a sun crust on steep solar aspects, and facetted snow in sheltered areas.
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
Tuesday Night
Mainly clear skies. Alpine temperatures reach a low of -9 °C. Ridge wind 15 km/h from the southwest. Freezing levels drop to valley bottom.
Wednesday
Mainly cloudy with sunny periods. Alpine temperatures reach a high of -6 °C. Ridge wind 10 km/h gusting to 30 km/h from the northwest. Freezing levels rise to 1400 meters.
Thursday
Mainly sunny. Alpine temperatures reach a high of -5 °C. Ridge wind variable 10 km/h. Freezing levels rise to 1500 meters.
Friday
Mainly sunny. Alpine temperatures reach a high of -3 °C. Ridge wind southeast 15 km/h. Freezing levels rise to 1700 meters.
More details can be found in the Mountain Weather Forecast.
Terrain and Travel Advice
- Be especially cautious as you transition into wind affected terrain.
- Avoid freshly wind loaded terrain features.
- 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
Storm Slabs
A warm windy storm has built reactive storm slabs at alpine and treeline. Watch for deeper pockets on north and east slopes where southwest winds have deposited storm snow into lees. Expect storm slabs to remain reactive to human triggering even though natural activity is tapering off.
If triggered, storm slab avalanches may step down to deeper weak layers resulting in large avalanches.
Aspects: All aspects.
Elevations: All elevations.
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 15th, 2023 4:00PM
