Continue to assess for slab properties within the recent snow, where storm and wind slabs will be most likely triggered. Cold weather increases the consequence of any incident.
Storm slabs continue to be triggered between about 30 and 100 cm deep, either within the most recent snow since Tuesday or at the base of the storm snow from last weekend. Wind slabs are also found in wind-exposed terrain on all aspects due to variable wind directions. These slabs may continue to linger due to the cold weather limiting bonding.
A weak layer of facets exists near the base of the snowpack. The likelihood of human triggering is low given the layer's deep burial depth. Suspect terrain for human triggering includes steep, thin, shallow, and rocky terrain, which is often found near ridgelines.
We continue to receive reports of many natural, explosive, and human-triggered storm slab and wind slab avalanches. The storm slab avalanches are generally occurring within the most recent storm snow since Tuesday or about 100 cm deep at the base of the snow that accumulated last weekend. Wind slab avalanches are occurring on all aspects in wind-exposed terrain where recent strong wind redistributed the storm snow. Avalanches are most often occurring at treeline and alpine elevations and are mostly small to large (size 1 to 2.5). We anticipate that similar avalanche activity will continue on Friday, since bonding of this snow will be slow with the cold weather.
Wednesday's clear skies allowed for observations of many deep persistent slab avalanches , which were large to very large (size 2 to 3.5). They were all naturally triggered, on all aspects, and between 2200 m and 2800 m in elevation. Many of the avalanches were triggered from rapid wind loading and from shallower avalanches stepping down to the basal facets. Although many of the avalanches occurred in unrideable terrain, they are evidence that the layer is still triggerable. Riders should continue to avoid thin snowpack areas, which are often found near ridgelines.
Storm slabs formed from Monday night's 20 to 50 cm of snow. The snow fell with southwest wind which has now switched to easterly wind, meaning wind slabs may be found on all aspects.
Around 80 to 100 cm of snow may overly a small layer of surface hoar crystals that was buried mid-February. This layer is most likely found around treeline elevations in areas sheltered from the wind. The remainder of the mid-pack is strengthening.
A layer of large and weak facets that formed in November is deeply buried, found near the base of the snowpack. The likelihood of human triggering this layer is currently low given its depth. However, it is still best to avoid steep, thin, rocky slopes near ridges at alpine and upper treeline elevations.
Thursday Night
Clear skies with no precipitation, 10 to 20 km/h east wind, treeline temperature -23 °C.
Friday
Clear skies with no precipitation, 10 to 20 km/h west wind, treeline temperature -21 °C.
SaturdayCloudy with snowfall, accumulation 5 to 10 cm, 20 to 40 km/h south wind, treeline temperature -15 °C.
SundayCloudy with snowfall, accumulation 15 to 30 cm, 20 to 40 km/h southwest wind, treeline temperature -13 °C.
More details can be found in the Mountain Weather Forecast.
