Southwesterly winds continue to form wind slabs on lee and cross-loaded terrain features in the alpine. Use caution when transitioning into wind affected terrain and avoid wind loaded slopes below ridgetops.
Southwesterly winds have formed wind slabs on lee and cross-loaded features below alpine ridgetops.
Large cornices are present throughout the region and are capable of triggering large avalanches when they fail. Cornice failures are most common during windy or warm weather.
The persistent slab problem appears to have been put to rest in deep snowpack areas in the west of the region, but on the eastern slopes (e.g. Kakwa/Tumbler Ridge) there were large natural avalanches last week.
Steep, rocky slopes with a shallow or thin to thick snowpack in the alpine are the most likely places to trigger these persistent weak layers.
WEDNESDAY NIGHT: Clear / Strong, southwest ridgetop wind / alpine low temperature -9 / Freezing level valley bottom.
THURSDAY: Increasing cloud in PM, then 5-10 cm. overnight / Strong, southwest ridgetop wind / alpine high temperature 0 / Freezing level 1900 m.
FRIDAY: Mix of sun and cloud / Strong, southwest ridgetop wind / alpine high temperature -2 / Freezing level 1500 m.
SATURDAY: Mix of sun and cloud / Moderate, northwest ridgetop wind / alpine high temperature -9 / Freezing level 800 m.
A few naturally triggered size 2 wind slabs on northerly aspects in the alpine were reported on Tuesday.
Our field team found some large and disturbingly wide avalanches in the Hasler last week, with lots of compelling images in their MIN report here. It's suspected that these are running on facets that are about 80 cm below the surface.
The northern portion of the region around Pine Pass got around 35 cm. of snow last weekend, but much less fell in the rest of the region. Southwesterly winds have formed wind slabs on lee and cross-loaded features below alpine ridgetops.
Sun crust exists on solar aspects and a temperature crust may exist on all aspects up to 1800 m. Large cornices are present throughout the region and are capable of triggering large avalanches when they fail. Cornice failures are most common during windy or warm weather.
About a metre of snow covers a weak layer of facets buried mid-February. Slightly deeper there is a widespread persistent weak layer from late January/early February that consists of surface hoar. It is most prevalent around treeline elevations, but likely reaches into the alpine and in openings below treeline too. These layers are both significantly shallower in the east of the region. Steep, rocky slopes with a shallow or thin to thick snowpack in the alpine and steep, open slopes at treeline are the most likely places to trigger these persistent weak layers. Large loads such a cornice falls or multiple sleds on the same slope often trigger slopes that single rider couldn't trigger.
