Avalanche Forecast
Regions: Dogtooth, East Purcell, Purcells, West Purcell.
The possibility of triggering a deep persistent slab avalanche remains the main concern. The sun packs a punch this time of year, so minimize your exposure during peak daytime warming.
Confidence
Moderate
Avalanche Summary
On Wednesday there were still reports of a few natural and explosives triggered storm and wind slab avalanches to size 2 and 3 which were suspected of having stepped down to deeper layers of facets.
On Tuesday there was a widespread natural avalanche cycle. Numerous storm slab and wind slab avalanches were observed on all aspects in the alpine and at treeline, up to size 2.5. Three naturally triggered size 2.5-3 deep persistent slab avalanches were observed in the Dogtooth range running in steep rocky terrain. Evidence of a size 4 natural deep persistent slab avalanche was observed in the western Purcells.
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
15-30 cm of wind-affected storm snow falling earlier in the week overlies wind-affected snow in open areas, facetted snow in sheltered areas and a thin sun crust on steep solar slopes.
Buried surface hoar can be found 70-90 cm deep in sheltered terrain features. A thin sun crust exists at the same depth on steep south-facing terrain.
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 continue to be a concern.
Weather Summary
Thursday Night
Cloudy with clear periods. Treeline temperature -7 °C. Wind light southwest.
Friday
Mainly sunny. Treeline temperature -2 °C. Wind light southwest. Freezing level rising to 1600m.
Saturday
Mainly sunny. Treeline temperature -1 °C. Wind light southwest. Freezing level rising to 1700m.
Sunday
Mainly sunny. Treeline temperature 0 °C. Wind light southwest. Freezing level rising to 1800m.
More details can be found in the Mountain Weather Forecast.
Terrain and Travel Advice
- Be especially cautious as you transition into wind affected terrain.
- Minimize exposure to sun-exposed slopes when the solar radiation is strong.
- Avoid freshly wind loaded features, especially near ridge crests, roll-overs and in steep terrain.
- Avoid areas with a thin or variable snowpack.
- If triggered, storm slabs in-motion may step down to deeper layers and result in very large avalanches.
Avalanche Problems
Storm Slabs
15-30 cm of storm snow has settled with warm temperatures into a reactive storm slab over a variety of surfaces. Be extra cautious on north and east slopes where southwest winds have built deeper pockets of storm slab.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood: Possible
Expected Size: 1 - 2.5
Deep Persistent Slabs
The base of the snowpack remains very weak. Very large human triggered avalanches are possible at treeline and above.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood: Possible
Expected Size: 2.5 - 4
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.
Be aware these layers can be remotely triggered (from a distance).
Aspects: All aspects.
Elevations: All elevations.
Likelihood: Unlikely - Possible
Expected Size: 1.5 - 3