An avalanche cycle will occur starting on Thursday as a significant storm is on the way, starting Wednesday afternoon through to Friday. After the long spell with minimal snow, expect avalanches to release easily and be careful in all locations as things change. Avoid all avalanche terrain on Thursday and Friday.
SW winds in the strong to extreme range have built wind slabs in lee terrain, up to 60 cm deep in some locations. Expect easy triggering in immediate leeward areas; so avoid obvious lee and crossloaded locations. Natural avalanches have been limited, but humans have been triggering them.
Both ski areas reported widespread windslabs and lots of avalanche control - Sunshine threw 25 shots and got 14 avalanches up to size 1.5. Lake Louise described windslabs up to 60 cm deep from the deep drifting, but no avalanches larger than size 1.5.
Windslab development has been widespread since Monday, and these are reactive to human triggering. In some areas, the Jan 24 surface hoar or crust is 25 to 35 cm down at treeline and below. Starting Wednesday afternoon, the snowpack's stability will deteriorate rapidly as the storm arrives and an avalanche cycle begins.
The weather begins to change on Wednesday as a strong westerly flow establishes itself, and by Thursday, we expect a significant storm to be upon us. This setup is the classic westerly flow collision with cold arctic air to the east. Some forecasts are calling for 35-40 cm of snow by Friday, along with winds exceeding 80 km/h. If this unfolds, we can certainly expect to see an avalanche cycle.
