The recent storm snow is expected to remain reactive at higher elevations, especially in wind loaded terrain. If the sun comes out for extended periods, the danger rating may be higher and extra caution will be needed around steep sun exposed slopes.
Summary
Confidence
Moderate - Timing or intensity of solar radiation is uncertain on Sunday
Weather Forecast
Unsettled conditions are forecast for Sunday with snow flurries and sunny breaks both expected. Alpine wind is expected to be light to moderate from the northwest. Freezing levels are forecast to fall to around 1100 m Saturday overnight and reach around 1500 m Sunday afternoon. Mainly sunny conditions are expected on Monday with some clouds and light alpine wind. Freezing levels are forecast to reach around 1700 m in the afternoon. Sunny conditions are currently forecast for Tuesday with freezing levels reaching around 2000 m and light alpine wind.
Avalanche Summary
On Friday, a natural size 2 storm slab avalanche was observed on a southeast aspect at 2250 m. A natural size 2.5 persistent slab was reported on west and northwest aspects at 2300 m and was 60-80 cm deep. Solar triggered loose wet avalanches up to size 2.5 were also observed throughout the region. A skier triggered a size 2 cornice on a northeast aspect which triggered a soft slab on the slope below. On Thursday, several natural storm slab avalanches up to size 2.5 were observed. Several natural cornice releases triggered slabs up to size 3, many of which released on the late-March crust down 40-80 cm. A skier also triggered a 30 cm thick storm slab which stepped down and released a size 2.5 persistent slab which failed on the late-March crust down 80-100 cm. On Sunday, the recent storm snow is expected to remain reactive to human triggering, especially in wind loaded terrain. If the sun is out for sustained periods of time, natural solar triggered sluffing should be expected from steep sun exposed slopes as well as the possibility of natural cornice releases.
Snowpack Summary
The new snow on Saturday likely buries a widespread sun crust which is expected to have formed on Friday. This crust caps 60-90 cm of moist snow that has accumulated over the past week in the region. Periodic high freezing levels and solar exposure over the past week has formed a variety crusts in the upper snowpack below around 2000m. This all overlies a rain crust that was buried on March 21 which extends into the alpine. This crust was recently reactive to heavy triggers and several avalanches released on it during the recent solar cycle. At elevations above around 2100m, the February persistent weak layers may still be lingering down around 100-150cm and weak basal facets may still be lingering in shallow snowpack areas. These layers appear to have gone dormant but isolated avalanches could still have the potential to step down in the right conditions.
rbuhler,
Avalanche Canada
