Avalanche Forecast

Moderate - Timing or intensity of solar radiation is uncertain

A ridge of high pressure is expected to keep the region dry for the next few days. Mostly sunny conditions are expected on Sunday with a few clouds and moderate alpine wind from the northwest. Freezing levels are forecast to reach around 1000 m or so in the afternoon. Sunny conditions are expected for Monday and Tuesday with mainly light alpine wind on Monday and moderate wind on Tuesday. Freezing levels are forecast to climb to around 2500 m on Monday and remain there on Tuesday. A temperature inversion will likely develop and temperatures may be colder at valley bottom than in the alpine.

On Friday, natural storm slab avalanches up to size 3 were reported. Skiers and explosives also triggered numerous avalanches. Most of this activity had slab thickness of 20-50 cm but some of the slabs were up to 1 m thick. In the mountains west of Invermere, explosives triggered four persistent and deep persistent slab avalanches on Friday. This activity was on east and southeast aspects and released 1.5-2.5 m deep. On Thursday, a remotely triggered avalanche in the Dogtooth Range broke a few younger trees in the runout. Check out the MIN post for more details or click here.On Sunday, the recent storm snow is expected to remain reactive to human triggering, especially in wind affected terrain. A lingering weak layer below the recent storm snow may increase the size and propagation potential of avalanches. Extra caution is recommended during the heat of the afternoon, especially on sun exposed slopes. This will become increasingly important on Monday and Tuesday as freezing levels climb. We are entering the first period of substantial warming following months of sustained cold conditions. Any weaknesses lingering in the snowpack will be tested in the coming days.

40-60 cm of storm snow has typically accumulated of the past few days. Recent strong winds from the south and west have redistributed this snow in exposed terrain forming touchy wind slabs. Weaknesses exist within this recent storm snow with reports of 'upside-down' conditions and easy shears within the top 60 cm. All this new snow is also bonding poorly to the previous snow surface from early February that includes sun crust on steep sun-exposed slopes, faceted snow, as well as surface hoar on sheltered open slopes. A persistent weakness buried mid January is now down 80-150 cm and consists of buried surface hoar in sheltered areas, sun crust on south aspects, and/or faceted old snow. It has generally stabilized but may be sensitive to triggering in isolated areas where surface hoar is preserved. This and deeper persistent weaknesses remain concerns isolated to shallow snowpack areas where they lie closer to the surface. These layers are expected to get tested with the upcoming period of sustained warming, and if they wake up, very large avalanches are possible.