Regions
Banff Yoho Kootenay.
Keep your eyes on the alpine when the strong winds begin to blow again on Friday. There is still enough snow to transport and create further instabilities on lee features.
Weather Forecast
We are in for a windy day in the alpine tomorrow, with strong to extreme values from the NW. Freezing level likely will be up to 1600m, but no plus temp's in the alpine are expected. No snow expected in our region on Friday, but a cold front passing through on Saturday may deliver a short, intense snow storm in the afternoon.
Snowpack Summary
Strong to extreme winds in the region have sculpted windslabs in the high alpine. A field team in the Little Yoho Valley reported easy shear tests on the storm slab interface. A different field team in Kootenay reported 10-15cm of storm snow with small cornice growth and soft slabs at ridge-top. Both teams observed a weak snowpack where shallow.
Avalanche Summary
Observations from Yoho included several size 1.5-2 soft slabs in the alpine, failing in the storm snow, up to 60cm thick. Several size 1.5-2 loose avalanches from NE-SE alpine terrain in Kootenay were observed today, along with shooting cracks in the snow near ridge-crests.
Problems
Wind Slabs
Wind Slab avalanches are the release of a cohesive layer of snow (a slab) formed by the wind. Wind typically transports snow from the upwind sides of terrain features and deposits snow on the downwind side. Wind slabs are often smooth and rounded and sometimes sound hollow, and can range from soft to hard. Wind slabs that form over a persistent weak layer (surface hoar, depth hoar, or near-surface facets) may be termed Persistent Slabs or may develop into Persistent Slabs.