Avalanche Forecast
Regions: Purcells.
Confidence
Fair - Intensity of incoming weather is uncertain
Weather Forecast
Wednesday night and Thursday: Precipitation tapering off overnight as the system moves across the region. Winds should pick up in the evening to strong speeds from the W and slow down a bit during the day Thursday. Temperatures lowering to around -8 C in the alpine and freezing levels at the surface. Friday:Â Another system is approaching which should leave some light precipitation during the day with strong W winds that should ease in the afternoon. Similar temperatures are expected. Saturday: More precipitation, cool temperatures and lighter winds from the W.
Avalanche Summary
A couple natural slab avalanches on S-SW aspects size 2.5 were reported in the Northern part of the region. One would have initiated in a shallow/crossloaded feature and would have stepped down from a 5 cm deep surface hoar instability to a 30 cm deep facet instability and then to the old facet/crust combo at the bottom of the snowpack down 85 cm. A skier triggered size 2 slab avalanche was also reported in the central part of the region which would also have initiated in a cross-loaded feature on a NW aspect. Suspect failure on the January 4th surface hoar down around 40 cm.
Snowpack Summary
The new snow will fall on a variety of surfaces; windslabs in the alpine, facets, surface hoar below treeline in sheltered areas and a suncrust on South facing slopes. New windslabs and some sluffing in sheltered terrain is expected. These new layers will most likely be touchy for a certain time.The surface hoar layer below the 40-60 cm of generally well settled snow is still a concern to professionals, especially below 1900 m. in sheltered-shady areas and on S aspects. It still produces sudden planar shears in those areas as well as some resistant planars. A strong mid-pack overlies a weak facet/crust layer near the base of the snowpack, which is now considered inactive.
Avalanche Problems
Storm Slabs
Aspects: All aspects.
Elevations: All elevations.
Likelihood: Likely
Expected Size: 1 - 5
Persistent Slabs
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood: Possible
Expected Size: 2 - 5