Ongoing snowfall and strong southerly winds will add more load to already thick storm slabs and large cornices. Conservative terrain selection remains critical on Sunday.
Summary
Confidence
Moderate - Intensity of incoming weather systems is uncertain
Weather Forecast
Another 5-10cm of snowfall is expected Saturday overnight with freezing levels around 1000m and moderate to strong alpine winds from the south. 5-15cm of snowfall is expected during the day on Sunday with freezing levels around 1300m and moderate to strong southerly winds. Light snowfall is forecast to continue Sunday night. Mostly dry and cloudy conditions are expected for Monday with snow flurries and sunny breaks both possible. Freezing levels are expected to stay around 1300m or lower and alpine winds are forecast to be light from the southwest. A mix of sun and cloud is forecast for Tuesday with freezing levels below 1300m and light alpine winds.
Avalanche Summary
On Friday, two natural cornice releases were reported. One was a size 3 cornice release on a north aspect that did not trigger a slab on the slope below. The other triggered a size 2 storm slab with a 50cm thickness. Explosives triggered two size 2 storm slabs that were 50 and 70cm thick. A skier remotely triggered a size 2 storm slab on a north aspect which was suspected to have slide on a melt-freeze crust. On Thursday, a natural avalanche cycle occurred during the storm with storm slabs up to size 3 reported at treeline and in the alpine. Explosives also triggered numerous storm slab avalanches up to size 2.5. Slab thickness was typically 30-40cm and up to 100cm thick in wind loaded areas. Skiers triggered several small avalanches in wind loaded features and on steep or unsupported features. Loose wet sluffing was also reported from lower elevations that saw rain. Storm slabs are expected to remain touchy to human-triggering on Sunday and natural activity is possible in freshly wind loaded terrain.
Snowpack Summary
Up to 75cm of recent storm snow is being reported in sheltered areas with up to 150cm in wind loaded areas. Weaknesses within or at the base of the new storm snow may need a couple days to settle and strengthen. Extreme southerly winds have created very deep and dense slabs in lee terrain, probably well below ridge crests, while scouring windward slopes. Ongoing stormy weather has also encouraged extensive cornice growth. The mid and lower snowpack are strong and well-settled.
rbuhler,
Avalanche Canada
