Avalanche Forecast

Moderate - Intensity of incoming weather systems is uncertain on Thursday

THURSDAY: Flurries increasing throughout the day with 10-20 cm of snow possible by the afternoon, strong southwest wind, freezing level rising to around 1500 m.FRIDAY: Flurries continue over Thursday night and into Friday and bring another 10-20 cm of snow, clearing in the afternoon, strong southwest wind easing throughout the day, freezing level rising to around 1200 m.SATURDAY: Sunny, light wind, freezing level rising to around 1500 m.

On Tuesday, a size 1 wind slab was skier-triggered on a south aspect at 2200 m and nearby explosive control produced a size 2 wind slab. No other notable activity was reported.The most recent report of a persistent slab avalanche was on Sunday, when a skier accidentally triggered a large avalanche on a north treeline slope in the Rossland area (see details here). The avalanche failed on a surface hoar layer 80 cm below the surface. Looking ahead, persistent weak layers could be stressed by the weight of the new snow or by the warming that will follow the storm.

Up to 20 cm of new snow could accumulate by Thursday afternoon, with even deeper deposits possible at higher elevations. The new snow is falling on mostly unconsolidated snow from last week's storm and possibly on a sun crust on south-facing slopes.A mix of interfaces exist 50-100 cm below the surface, including small surface hoar on polar aspects and a crust on solar aspects. These layers have consistently been reactive in snowpack tests, suggesting they could potentially remain reactive to human triggers as well.Deeper weak layers that formed in January and December have gained strength and gone dormant at this time. They include several surface hoar and facet layers 1 to 2 m below the surface and a crust/ facet interface near the base of the snowpack.