An avalanche cycle is continuing with up to 45 cm of heavy wet storm snow overlaying a generally weak and faceted lower snowpack. Conservative terrain choices without overhead hazards are recommended for skiers and climbers.
With all the new snow, lots of sluffing and dry loose avalanches are occuring off extreme terrain in the alpine and at treeline. These sluffs are often triggering storm or deep persistent avalanches in lower angled terrain.
Up to 45 cm of heavy storm snow is sitting on a weak interface of surface hoar, facets and some sun crust from Dec 2. This weak layer is easily triggered and the resulting avalanches often step down to the basal facets resulting in even larger slides.
The mid and lower snowpack are weak and faceted in most areas with facets, depth hoar and a spotty crust from late Oct at the base of the pack. Many avalanches are occuring on this basal weakness resulting in full depth avalanches up to size 2.5.
Numerous natural, skier and explosive triggered avalanches up to size 2.5 were reported on Wednesday, including remotely triggered avalanches during ski cutting. These were failing as storm slabs and deep persistent slabs at all elevations. Widespread whumphing and cracking was reported in areas not steep enough to avalanche.
Up to 45 cm of dense storm snow overlays a weak Dec 2 layer of surface hoar, facets, and some sun-crust on steep south aspects. Previous strong SW winds have formed windslabs in alpine and tree-line locations. The mid and lower pack is generally weak and faceted. Snow depths range from 50-80 cm at tree-line and up to 110+ cm in deeper alpine locations.
The storm will bring more snow to the forecast area with another 10-20 cm possible overnight and into Thursday evening. Winds will switch to NE in the Banff area with an upslope finish to the storm. Freezing levels will hover around 1300 m then lower to valley bottom on Thursday. Winds stay in the light to moderate range.
For more information click Mountain Weather Forecast.
