Purcells

Spring Conditions. Ongoing sunny weather and rapidly rising freezing levels will increase the likelihood of large destructive wet slab avalanches, especially if there is little or no overnight refreeze of the snow surface.

No new avalanches reported in this region. Most commercial operations have closed for the season, and data is becoming sparse. However, with the forecasted warm up Sunday and especially Monday, I would expect sporadic large and destructive wet slab avalanches.

SUNDAY: Freezing Level: 3000m, sunny, light southerly winds. MONDAY:  Freezing Level: 3600m, sunny, light southerly winds. TUESDAY:  Freezing Level: 3600m, sunny, light southerly winds.

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. Cornices are large, fragile, and could trigger deep slab avalanches that run to valley bottoms. 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.