Avalanche Forecast
Regions: Purcells.
Confidence
Moderate - Timing or intensity of solar radiation is uncertain
Weather Forecast
A ridge of high pressure dominates for the next several days. A mix of sun and cloud is expected on Wednesday with light alpine winds from the west. Freezing levels are expected to drop below valley bottom overnight and reach around 1500m in the afternoon. Mostly sunny conditions are expected for Thursday with light westerly winds and freezing levels reaching around 1800m in the afternoon. Mostly sunny conditions are expected on Friday with moderate southwest winds in the alpine and freezing levels reaching well over 2000m.
Avalanche Summary
On Monday, a few size 1 ski cuts were reported from steep convex features. These were on an east aspect at treeline and were 20-40cm thick. Skier triggered sluffing from steep terrain features below treeline was also reported. Reports from Sunday include a natural Size 2 persistent slab avalanche and a Size 2.5 cornice failure. Several Size 1 skier-triggered wind slabs were also reported and explosives control produced slab avalanches up to Size 3. On Saturday one person was killed and another was hospitalized in a large avalanche in the Quartz Creek area west of Golden. This size 3 snowmobile-triggered slab avalanche occurred on a S-SW aspect in the alpine and is suspected to have released on the Feb. 12 interface.
Snowpack Summary
20-30 cm of snow in the past few days has added to the recent storm slab bonding reasonably well to a crust 40-60 cm below the surface, that was buried on February 12th. However, in isolated areas (such as shady sheltered treeline slopes) there may be a weak layer of surface hoar at the storm snow/crust interface that is touchy to human triggers and may result in wide propagations. The early January surface hoar/ facet layer is typically down 70-120 cm. Avalanche activity at this interface has tapered-off over the past week, but I'd be reluctant to trust this potentially destructive layer just yet. In general, the lower snowpack is well settled and strong, apart from some thin snowpack areas where basal facets exist.
Avalanche Problems
Persistent Slabs
Aspects: All aspects.
Elevations: All elevations.
Likelihood: Possible - Likely
Expected Size: 1 - 4
Wind Slabs
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood: Possible
Expected Size: 1 - 3
Cornices
Aspects: North, North East, East, South East.
Elevations: Alpine.
Likelihood: Possible
Expected Size: 1 - 4