Continued snowfall with strong wind overnight Thursday will increase the storm slab hazard. New snow is adding stress to the buried persistent weak layer and avalanches have been observed stepping down to this layer.
Pick conservative terrain and avoid exposure to overhead hazard.
Two persistent weak layers are buried down ~100 and ~130 cm. New snow combined with extreme winds could overload these weak layers triggering large, destructive avalanches. These weak layers are also still reactive to human triggering.
40-70 cm of storm snow will be redistributed by extreme Westerly winds. Touchy storm slabs have formed in all exposed terrain. Storm slabs in motion may step down to deeper layers resulting in large avalanches.
Natural avalanche activity up to size 3 on Thursday with explosives producing results up to size 3.5 in the highway corridor. Many of these avalanches stepped down to the persisant slab.
On Wednesday, field teams triggered small avalanches on a steep north aspects below treeline.
Storm slabs will continue to build with forecasted extreme winds and snowfall.
The incoming storm will further bury persistent weak layers and load them rapidly.
The Feb 9 surface hoar (SH) is down 90-120 cm and remains reactive in snowpack testing. The Feb 9 SH sits over a crust on solar aspects.
The Jan 26th layer, composed of surface hoar/facets/crust, is buried down 130-150 cm. The largest surface hoar is preserved in sheltered areas below treeline.
An intense storm continues through Friday. A total of 40-60 cm of snow is expected with extreme westerly winds.
Tonight Flurries, 10cm. High -6°C. Wind SW 40 gusting to 90 km/h. Freezing level (FZL) 1300m.
Fri Flurries 5-10 cm. Low -9°C. Winds W 25, gusting to 65 km/h. FZL 900m.
Sat Mix of sun and cloud. No precipitation. High -12°C. Winds West 15-35. FZL 600m.
Sun Mix of sun and cloud. High -4. Winds West 10-20. FZL 1300m.
