Tricky conditions are expected to persist at higher elevations with new snow and wind building slabs as well as the continuing possibility of avalanches releasing on deep weak layers. Conservative terrain selection remains highly recommended.
Summary
Confidence
Moderate - Intensity of incoming weather systems is uncertain on Saturday
Weather Forecast
5-15 cm of snowfall is expected Friday overnight with moderate to strong southwest wind in the alpine and freezing levels around 1000 m. Another 3-6 cm is expected on Saturday with the possibility of sunny breaks in the afternoon. Alpine wind is forecast to be moderate from the southwest and freezing levels are expected to reach around 1500 m. On Sunday, a mix of sun and cloud is expected with light alpine wind and freezing levels reaching around 1700 m. Mainly cloudy conditions are forecast for Monday with light snow flurries.
Avalanche Summary
On Thursday, a natural size 1.5 storm slab was observed on a NW aspect at 2450 m as well as solar triggered sluffing up to size 1.5 from steep sun exposed slopes. A natural cornice release triggered two pockets of deep slab in extreme terrain. A skier remotely triggered a size 2 wind slab from 20 m away on a north aspect at 2100 m. Skiers also triggered three size 1.5-2 wind slabs on northeast through southeast aspects between 2400 and 2800 m elevation. Explosives triggered six cornices up to size 3 but only one these cornices triggered a slab. On Wednesday, a natural size 2 was reported on a south aspect. A skier triggered a size 1 storm slab on a north aspect at 2200 m which was 15-25 cm thick. On Saturday, storm slabs are expected to be reactive at higher elevations, especially in wind loaded terrain and on steep convexities. Cornices are large and may become weak with daytime warming or during stormy periods. We are in a low probability, high consequence scenario for persistent slab avalanches failing on buried weak layers.
Click here for more details. Click here for photos of the recent large avalanche cycle.Snowpack Summary
15-30 cm of new snow overlies a rain crust below around 2000 m or a sun crust on solar aspects at higher elevations. Alpine wind has recently been strong mainly from south through west directions and has loaded leeward slopes in exposed terrain at treeline and in the alpine. Large cornices are also reported on northerly aspects in the alpine. The rain crust which formed last week is now down 40-50 cm and generally seems to be well bonded to the surrounding snow. The February weak layers are down 120-150 cm and woke up during the recent storm cycle with many avalanches stepping down. The deep mid-December facet layer and November rain crust both still linger near the bottom of the snowpack and a few avalanches and cornice falls have stepped down to these layers recently resulting in very large avalanches.
rbuhler,
Avalanche Canada
