Avalanche Forecast

Overcast with light precipitation and light winds overnight. Overnight freezing level is expected to be 2500 metres. Moderate rain (10-15 mm) during the day Friday combined with light winds and freezing levels slowly descending to 2000 metres. Light rain and light winds on Saturday, mix of snow and rain in the high alpine. Daytime freezing levels around 2000 metres. Gradual cooling with a mix of snow and rain on Sunday; freezing levels down to 1000 metres by the end of the day.

No new avalanches reported. On Tuesday there was a size 3.0 wet slab avalanche down to the ground that was explosives triggered in the Duffey Lake area, the avalanche released on a northwest aspect at 2200 metres and ran to valley bottom. We have a MIN report from Monday of a close call with a size 2.5 wet slab avalanche on a northeast aspect in the alpine on Hour Peak on the McBride range traverse. A skier triggered the large avalanche that released down 30 cm on an old melt-freeze crust and propagated a fracture about 50 metres wide. Most commercial operations in the region have finished their season and data is becoming sparse.

Forecast cloud, cooling, and new snow at higher elevations will reduce the likelihood of loose wet and wet slab avalanches. Areas that get rain on top of a snowpack that has not re-frozen may continue to see sporadic wet slab avalanches. Monitoring the overnight freeze of the snow surface is very important. If the snow surface does not freeze overnight or if the crust is only a few cm thick, the effect of daytime heating or rain will weaken the snowpack much more quickly than it would if there is a well frozen thick crust. This is because the crust must first melt before the heat can weaken the snowpack. Low elevation and thin snowpack areas have become isothermal, meaning the snowpack is 0 degrees Celsius throughout. An isothermal snowpack is more prone to full depth wet slab avalanches during the heat of the day, especially on steep rocky faces.