Avalanche Forecast

Moderate - Forecast snowfall amounts are uncertain on Friday

FRIDAY: Overnight Thursday into Friday snow, accumulation 15-25cm then mostly cloudy with isolated flurries through Friday / Moderate to strong southwest wind / Alpine temperature -4 / Freezing level 1000m SATURDAY: Mix of sun and cloud / light south wind / Alpine temperature -3 / Freezing level 1400m SUNDAY: Cloudy with flurries / Light southwest wind / Alpine temperature 0 / Freezing level 1800m

Expect to see an increase in storm slab, wind slab and loose dry avalanche activity as new snow accumulates Thursday into Friday. On Wednesday reports indicated loose wet avalanches size 1.5-2 from southerly facing terrain at tree line. 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. 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.

15-25cm of new snow is forecast to fall Thursday into Friday morning. This new snow sits on mostly unconsolidated snow from last week and possibly on a sun crust on south-facing slopes.A mix of weak layers 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.