Watch for lingering wind slabs in high north facing terrain. Extra caution is needed around all steep sun exposed slopes as well any slopes exposed to large cornices.
Summary
Confidence
Moderate - Timing or intensity of solar radiation is uncertain
Weather Forecast
Mostly sunny conditions are expected on Monday with light alpine wind from the north. Freezing levels are forecast to drop to around 500 m Sunday overnight and reach around 1500 m on Monday afternoon. Increasing cloud cover is expected on Tuesday with light to moderate alpine wind from the south and freezing levels reaching around 1600 m in the afternoon. Light precipitation is forecast for Wednesday with strong alpine wind from the south and freezing levels reaching around 1800 m in the afternoon.
Avalanche Summary
On Saturday, numerous natural loose wet avalanches up to size 1.5 were observed on southeast through west aspects. A few natural cornice releases were observed which did not trigger slabs. Skiers were triggering small soft slab avalanches as well as loose sluffs. Explosives triggered three size 2 storm slabs as well as two large cornices which subsequently triggered storm slabs. 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 Monday, wind slabs on northerly aspects in the alpine may still be reactive to human triggering. Natural solar triggered sluffing is expected from steep sun exposed slopes and natural cornice releases are also possible when the sun is shining.
Snowpack Summary
A widespread surface crust is being reported on all aspects and elevations except for north facing terrain in the alpine. 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. In high north facing terrain, there may be 20-30 cm of new snow which accumulated Friday and Saturday. Recent strong alpine wind from the south has formed wind slabs in the alpine. 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 wind 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
