Avalanche Forecast
Regions: Dogtooth, East Purcell, Purcells, West Purcell.
Diligently maintain a conservative mindset. You may not see signs of instability on the surface however the deep persistent weak layer remains a major concern at the bottom of the snowpack.
Avoid shallow, rocky, and wind-loaded terrain where triggering slab avalanches is most likely.
Confidence
Moderate
Avalanche Summary
On Thursday, a natural cornice failure triggered a size 2 persistent slab in the Dogtooth range north of Golden. This avalanche occurred on a northwest aspect in the alpine .
On Wednesday, two, size 3 cornice triggered avalanches were observed near Golden. The avalanches happened on northerly aspects and stepped down to the ground. Explosives control triggered a few avalanches on both the deep persistent weak layer to size 2 and on the persistent weak layer to size 3.
On Tuesday, a natural size 2.5 persistent slab avalanche was observed near Golden on a south aspect at 2600 m.
On March 1st, a fatal avalanche incident involving a group of skiers occurred in the Purcell Mountains west of Invermere BC. The size three avalanche was triggered on a southwest facing slope at 2500 m. The weak layer of facets buried in late November that sits at the bottom of the snowpack was responsible for this avalanche.
Snowpack Summary
Up to 5 cm of low-density new snow overlies hard, wind-affected surfaces in open areas, surface hoar and facetted snow in sheltered areas and a sun crust on steep solar slopes.
Buried surface hoar sits 50-70 cm deep in sheltered terrain features, and a thin sun crust exists at the same depth on steep south-facing terrain. Several other layers from January can also be found in the top 100cm of the snowpack.
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
Friday night
Cloudy with flurries, up to 5 cm of accumulation. Alpine temperatures drop to a low of -14 °C. Light northeast ridge wind. Freezing level at valley bottom.
Saturday
A mix of sun and cloud with isolated flurries. Alpine temperatures reach a high of -9 °C. Ridge wind light from the southwest. Freezing level rises to 700 meters.
Sunday
Sunny with cloudy periods and isolated flurries. Alpine temperatures reach a high of -6 °C. Light ridge wind from the southwest. Freezing level rises to 1000 meters.
Monday
Mainly cloudy with snowfall, trace to 15 cm of accumulation. Alpine temperatures reach a high of 1 °C. Ridge wind 30 to 60 km/h from the southwest Freezing level rises to 2000 meters.
More details can be found in the Mountain Weather Forecast.
Terrain and Travel Advice
- Avoid steep, rocky, and wind effected areas where triggering slabs is more likely.
- Avoid areas with a thin or variable snowpack.
- Surface hoar distribution is highly variable. Avoid generalizing your observations.
- Remote triggering is a concern, watch out for adjacent and overhead slopes.
Avalanche Problems
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: Possible
Expected Size: 2.5 - 4
Wind Slabs
Friday's northeast wind and new snow may have formed small but reactive wind slabs most likely found on southwest-facing slopes. Wind slabs may bond poorly to the underlying crust.
Aspects: South East, South, South West, West, North West.
Elevations: Alpine, Treeline.
Likelihood: Possible
Expected Size: 1 - 1.5
Persistent Slabs
Numerous weak layers from January and February exist at all elevations on a variety of aspects. On shaded slopes, these layers generally present as surface hoar, and on sun-exposed slopes they present as facets and a crust.
Avalanches triggered on these layers can step down to the facets at the bottom of the snowpack resulting in a very large avalanche.
These layers can be remotely triggered. Avoid traveling below steep slopes.
Aspects: All aspects.
Elevations: All elevations.
Likelihood: Possible
Expected Size: 1.5 - 3