Continued reports of human-triggered persistent slab avalanches show buried weak layers remain sensitive
Careful snowpack evaluation and conservative decision-making are essential
South winds have redistributed recent snow into alpine and treeline lee terrain features. Wind slabs may be more reactive where they overlie a buried weak layer of surface hoar.
Two weak layers of facets and/or surface hoar that were buried mid-February and early March continue to be reactive to human triggering. Make conservative terrain choices and avoid exposure to overhead hazards.
On Friday, a size 1.5 and a size 2 human-triggered persistent slab avalanches were reported in open alpine features at 2000 m.
Reports from earlier this week observed both natural and human-triggered wind slab and persistent slab avalanche activity to size 3 in the alpine. These avalanches were 20 to 40 cm deep and were all suspected of running on a weak layer of surface hoar buried in early March.
Southerly winds have redistributed 20 to 40 cm of recent snow into deep pockets on lee slopes. This snow buried a widespread layer of large surface hoar crystals, which sits on a crust on solar aspects and at low elevations. This layer has been reactive in recent days where a slab has consolidated above.
A layer of facets, surface hoar and/or a crust from mid-February is buried 50 to 100 cm deep. This layer produced large natural and human-triggered avalanches last week.
The remainder of the snowpack is well consolidated with no concerns at this time.
Saturday Night
Cloudy with light flurries, 1 to 5 cm of snow. 20 to 30 km/h south ridgetop wind. Treeline temperature -10 °C.
Sunday
Cloudy with light flurries, 2 to 3 cm of snow. 15 to 25 km/h southwest ridgetop wind. Treeline temperature -8 °C.
Monday
A mix of sun and clouds. 15 to 30 km/h west ridgetop wind. Treeline temperature -11 °C.
Tuesday
Cloudy with light flurries, 1 to 5 cm of snow. 20 to 30 km/h southwest ridgetop wind. Treeline temperature -6 °C.
More details can be found in the Mountain Weather Forecast.
