Avalanche Forecast
Issued: Mar 13th, 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 blankets the region and has created reactive storm slabs. If triggered storm slab avalanches could step down to weak layers deep in the snowpack creating large destructive avalanches. Careful snowpack evaluation, cautious route-finding and conservative decision-making are essential for a safe day out in the mountains.
Summary
Confidence
Avalanche Summary
On Saturday, a few cornice failures were observed in the alpine during a brief period of direct sun. Observed failures did not trigger the slope beneath them. Check out the MIN report for more details.
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
By Tuesday morning 20-40 cm of storm snow overlies a variety of surfaces including small pockets of wind slab on exposed south and west slopes, 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
Monday Night
Cloudy with mixed precipitation, 10-16 cm new snow at higher elevations. Alpine temperatures reach a low of -5 °C. Ridge wind 20 km/h gusting to 50 km/h from the southwest. Freezing levels lower slowly from 1800 m to 1000 m.
Tuesday
Mainly cloudy with isolated flurries, trace accumulation. Alpine temperatures reach a high of -7 °C. Ridge wind 15 to 30 km/h from the southwest. Freezing levels 1100 meters.
Wednesday
A mix of sun and cloud with isolated flurries, trace accumulation. Alpine temperatures reach a high of -5 °C. Ridge wind 15 km/h gusting to 30 km/h from the northwest. Freezing levels rise to 1200 meters.
Thursday
Mainly sunny. Alpine temperatures reach a high of -2 °C. Ridge wind southwest 20 km/h. Freezing levels rise to 1500 meters.
More details can be found in the Mountain Weather Forecast.
Terrain and Travel Advice
- Continue to make conservative terrain choices while the storm snow settles and stabilizes.
- Storm snow and wind is forming touchy slabs. Use caution in lee areas in the alpine and treeline.
- Be especially cautious as you transition into wind affected terrain.
- Avoid rock outcroppings, convexities, and anywhere the snowpack is thin and/or variable.
Problems
Storm Slabs
20-40 cm of storm snow has settled with warm temperatures into a reactive storm slab over a variety of surfaces. Storm slabs will be particularly reactive on solar slopes where they may be poorly bonded to the underlying crust. Be extra cautious on north and east slopes where southwest winds have built deeper pockets of storm slabs.
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 14th, 2023 4:00PM
