Sea To Sky

Spring conditions with a brief return to winter in the alpine. Expect to find touchy wind slabs sitting on slippery crusts.

WEDNESDAY: Freezing level: 1500m, cloudy , light to moderate southerly ridgetop winds. THURSDAY: Freezing level: 1900m, mix of sun and cloud,  light southerly ridgetop winds. FRIDAY: Freezing level: 1500m, cloudy, light southerly ridgetop winds.

On Monday, a size 2.5 cornice triggered avalanche was reported on an east aspect at 2000m near Whistler.

Cornices are large, fragile, and could trigger deep slab avalanches that run to valley bottoms. Monitoring the overnight freeze of the snow surface is very important during the spring. If the snow surface does not freeze overnight or if the crust is only a few cm thick, the effect of daytime heating and solar radiation 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 sun can weaken the snowpack. Deeply buried weak layers in the mid snowpack and near the ground still have the potential to wake up and become active with a rapid warm up. While unlikely, releases on these deeply buried weak layers would result in very large avalanches. Glide cracks are widespread, active, and best avoided. 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.