Storm slabs overlying a persistent weak layer are creating dangerous avalanche conditions.
Careful snowpack evaluation and conservative terrain choices are essential right now.
A persistent weak layer of large surface hoar/ facets/ crust from late Januray is buried 40 to 80 cm and remains a significant concern. Avalanche activity has been prevalent on it this week, including some remote triggering.
40-50 cm of recent snow combined with strong winds formed reactive storm slabs. These slabs will be most reactive on lee slopes near ridgetops and in areas where they overlie a surface hoar layer.
On Sunday, there were numerous reports of natural, skier-triggered and remote-triggered avalanches across the region up to size 2.5. Some were storm slabs that stepped down to the late January persistent weak layer.
Storm slabs should slowly gain strength but may remain reactive, with the potential to step down to a persistent layer buried deep in the snowpack.
20 to 50 cm of settling storm snow is covering a new layer of surface hoar and/or a melt-freeze crust that formed on February 7th in many areas. Southwesterly winds will likely continue building thicker slabs on lee slopes near ridgetops.
At lower elevations and on sunny slopes, the snow surface may be crusty.
The late January persistent weak layer, consisting of surface hoar/facets/crust, is buried 40 to 80 cm. It has surprised people with its reactivity over the past week, especially in sheltered treeline features.
The mid and lower snowpack is well settled with no layers of concern.
Tuesday Night
Mostly cloudy. 1 to 3 cm of snow. 20 km/h west ridgetop wind. Treeline temperature -7 °C.
Wednesday
Mostly sunny. 20 km/h west ridgetop wind. Treeline temperature -7 °C.
Thursday
Mostly sunny. 40 km/h southwest ridgetop wind. Treeline temperature -5 °C.
Friday
Mostly cloudy. 1 to 5 cm of snow. 40 km/h southwest ridgetop wind. Treeline temperature -6 °C.
More details can be found in the Mountain Weather Forecast.
