The recent storm snow is expected to be reactive at higher elevations, especially in wind loaded terrain. Extra caution is needed around steep sun exposed slopes when the sun is out.
Summary
Confidence
Moderate - Timing or intensity of solar radiation is uncertain on Sunday
Weather Forecast
Unsettled conditions are expected on Sunday with a mix of sun and cloud as well as the possibility of isolated flurries. Alpine wind is expected to be light to moderate from the north. Freezing levels are forecast to fall to around 800 m Saturday overnight and reach around 1200 m on Sunday afternoon. Mostly sunny conditions are expected on Monday with light alpine wind and freezing levels reaching around 1500 m in the afternoon. A mix of sun and cloud is currently forecast for Tuesday with freezing levels reaching around 1800 m and moderate alpine wind from the south.
Avalanche Summary
On Friday, a natural size 2 wet slab was observed on an unsupported feature at 2250 m elevation on southerly aspects which stepped down to old weak layers. Explosives triggered a couple cornices size 2-2.5. On Thursday, several natural size 2 storm slabs and wet slabs were observed from steep sun exposed slopes as well as widespread loose wet avalanches. A natural size 2.5 persistent slab avalanche was observed which likely released on the mid-February weak layer. Natural cornices up to size 1.5 and explosive triggered cornices up to size 2.5 were also reported. A MIN post from Thursday shows a great example of a snowmobile triggered storm slab avalanche on steep feature.
Click here for more details.On Sunday, the recent storm snow is expected to remain reactive to human triggering, especially in wind loaded terrain. Natural solar triggered sluffing is expected from steep sun exposed slopes. Natural storm slab avalanches and cornice releases are also possible when the sun is shining.
Snowpack Summary
15-25 cm of new snow from Friday night overlies a widespread new crust which exists on all aspects below 1800 m and into the alpine on sun exposed aspects. Below around 2000 m, there may be multiple old crusts in the upper snowpack including the late-March crust which is now typically down 60-80 cm. The persistent mid-February crust/facet layer can still be found at the upper end of treeline and into the alpine. This layer is generally 120-170 cm deep but may be closer to the surface in wind scoured areas. Although there is growing confidence that this layer has generally gone dormant, a storm slab or cornice release in the right location may have the potential to trigger any of the deeply buried weak layers in the snowpack.
rbuhler,
Avalanche Canada
