Numerous size 1 to 2.5 explosive, natural and human-triggered slabs and cornices were triggered in the Whistler/ Blackcomb area last week. A few of these slabs stepped down to the mid-November crust up to 1 m deep, setting off very large avalanches. Most of these avalanches released in high alpine leeward north through east facing features.

The incoming storm is expected to greatly increase the likelihood of both natural and human-triggered avalanches.

35 to 65 mm of precipitation, combined with strong southerly winds, is forecast to fall by 4 pm Sunday. The snow/rain line elevation is uncertain and likely to fluctuate during the storm. There is potential for wet loose avalanches where the snow surface is wet. In the alpine, we expect to see reactive new storm slabs building as the new snow adds up.

A crust with facets, formed in mid-November, is buried around 60-120 cm, depending on the aspect. Storm slabs have the potential to step down to this layer.

The snowpack rapidly diminishes below 1200 m.

Saturday Night
Cloudy. 5 to 20 mm of precipitation as snow or rain at treeline. 50 km/h south ridgetop wind. Treeline temperature 2 °C. Freezing level between 1900 - 2100 m.

Sunday
Cloudy. 30 to 45 mm of precipitation as snow or rain at treeline. 60 km/h south ridgetop wind. Treeline temperature 1 °C. Freezing level between 2000 - 1600 m.

Monday
Cloudy. 60 to 100 mm of precipitation as rain or snow at treeline. 50 km/h south ridgetop wind. Treeline temperature 3 °C. Freezing level between 1500 - 2500 m.

Tuesday
Mostly cloudy. 20 to 35 cm of snow. 40 km/h south ridgetop wind. Treeline temperature -3 °C. Freezing level 1200 m.

More details can be found in the Mountain Weather Forecast.

No recent avalanches have been reported. However, observations are extremely limited in this area.

If you're heading out into the backcountry, please consider sharing your observations on the MIN.

A storm is expected to bring up to 60 mm of rain on Sunday, continuing to saturate an already wet snowpack. Freezing levels may fluctuate, but it's expected that only the highest alpine elevations could see snowfall instead of rain.

Alpine areas should be carefully assessed for new storm slabs before committing to slopes.

Treeline areas currently hold an estimated 20 to 50 cm of snow, which diminishes rapidly below 1500 m.

Saturday Night
Mostly cloudy. 5 to 15 mm of rain at treeline. 60 km/h south ridgetop wind. Treeline temperature 5 °C. Freezing level 2500 to 2100 m.

Sunday
Cloudy. 30 to 50 mm of rain or snow at treeline. 60 km/h south ridgetop wind. Treeline temperature 2 °C. Freezing level 2000 m.

Monday
Cloudy. 75 to 100 mm of rain at treeline. 80 km/h south ridgetop wind. Treeline temperature 5 °C. Freezing level 2600 m to 2000 m.

Tuesday
Cloudy. 20 to 35 cm of snow. 50 km/h south ridgetop wind. Treeline temperature 0 °C. Freezing level 1000 to 1500 m.

More details can be found in the Mountain Weather Forecast.

On Thursday, several size 2-2.5 explosive-triggered slabs occurred in the Duffey area. They were suspected of having stepped down to the mid-November persistent weak layer.

On Tuesday, a deep and large slab (size 2.5-3) was observed on Matier’s East Ridge. (See photo below) This slab was also suspected of having failed on the persistent weak layer.

The incoming storm is expected to increase the likelihood of both natural and human-triggered avalanches.

15 to 35 mm of precipitation, combined with strong southerly winds, is forecast to fall by 4 pm Sunday. The snow/rain line elevation is uncertain and will likely fluctuate during the storm. Teeline and below could see rain with wet loose avalanches. In the alpine, we expect to see reactive new storm slabs building as the new snow adds up.

A crust with facets, formed in mid-November, is buried around 50 to 100 cm at alpine and treeline elevations. Storm slabs have the potential to step down to this layer.

Snowpack height averages around 100 to 180 cm at treeline and decreases rapidly below 1500 m.

Saturday Night
Cloudy. 5 to 15 mm of precipitation as snow or rain at treeline. 40 km/h south ridgetop wind. Treeline temperature 1 °C. Freezing level 1900 m.

Sunday
Mostly cloudy. 10 to 25 mm of precipitation as snow or rain at treeline. 40 km/h south ridgetop wind. Treeline temperature 0 °C. Freezing level 1800 m.

Monday
Mostly cloudy. 30 to 50 mm of rain at treeline. 40 km/h south ridgetop wind. Treeline temperature 4 °C. Freezing level 2300 m.

Tuesday
Mostly cloudy. 5 to 15 cm of snow at treeline. 30 km/h southwest ridgetop wind. Treeline temperature -3 °C. Freezing level 1300 m.

More details can be found in the Mountain Weather Forecast.