Dangerous avalanche conditions exist. Careful snowpack evaluation, cautious route-finding, and conservative decision-making are essential.
New snow and southwest wind have created fresh wind slabs, which will likely be more reactive in leeward terrain and around ridge crests. If triggered, a wind slab may step-down to deeper layers resulting in large avalanches.
Weak layers remain a concern, especially in north-facing terrain where snowpack depth is variable. Avoid steep and shallow rocky features where human triggering is possible.
On Friday, explosive control in the region produced four size 2.5 persistent slab avalanches on northwest alpine features. A few dry loose avalanches were also observed up to size 1.5.
On Monday, two very large persistent slabs were remotely triggered by skiers and a snowcat in the Birkenhead area. They occurred on west and east alpine slopes and ran full path. Crowns were 75 to 100 cm and one of them stepped down to the mid-February week layer.
15 to 30 cm of new snow and southwest winds reactive wind slabs on lee slopes at higher elevations. New snow overlies wind-affected snow at upper elevations and a melt-freeze crust on southerly slopes up to 2000 m. This sits over 80 to 150 cm of settling storm snow from the past week.
The early March weak layer of facets or surface hoar on a crust is now down 100 to 150 cm and is present on all aspects except high north-facing slopes. Very large avalanches (size 3 to 3.5) were reported on this layer in the past week.
Weak layers formed in mid-February and late-January are now buried 110 to 190 cm deep.
Friday Night
Partly cloudy. 10 to 25 km/h southwest ridgetop wind. Treeline temperature -8 °C. Freezing level drops to valley bottom.
Saturday
Mix of sun and clouds. 15 to 25 km/h southwest ridgetop wind. Treeline temperature -5 °C. Freezing level 1200 m.
Sunday
Mostly cloudy with isolated flurries, 2 cm of snow. 30 to 40 km/h southwest ridgetop wind. Treeline temperature 0 °C. Freezing level 1600 m.
Monday
Mix of sun and clouds. 20 to 30 km/h southwest ridgetop wind. Treeline temperature +2 °C. Freezing level 2000 m.
More details can be found in the Mountain Weather Forecast.
