Avalanche risk increases in the Rockies – with more snow expected

One man has died after an early-season, wind slab avalanche in Kananaskis Saturday.

Above seasonal temperatures, strong chinook winds and snow have all been persistent in the mountains over the past few days with more snow expected Monday.

According to the Avalanche Canada's Nov. 12 forecast, there have already been a number of “natural and explosive triggered avalanches” within the previous 48-hour period.

The agency reports the snowpack saw an additional 10 to 30 centimetres of snow over the weekend with “generations of wind slabs within the snowpack which overlay a very weak base.”

Some of those wind slabs have failed naturally – including the deadly one on Saturday.

Strong west wind along with an additional 5 to 10 centimetres of snow was expected for the region on Monday.  

A wind slab avalanche can occur when the density of one layer of the snow pack changes due to external influences, resulting in one or more layers of stiff, wind-deposited snow situated on top of a weak layer. With a strong enough wind that new slab can settle on the other side of a mountain ridge – often at the top of a lee slope.  

There are eight types of avalanches that Avalanche Canada forecasts for, with the avalanche season beginning in November and continuing through May.

As of Nov. 13, there were already a few locations rated between a moderate to high avalanche risk, with most of those areas on the Alberta side of the Rockies.

A surface low pressure system will develop over central Alberta Monday with snow expected north of the low and above seasonal conditions forecast for the warm sector.

The daytime high in Calgary should hit 12C, which is 9 degrees above average.

Temperatures will drop to a seasonal 3C by Wednesday, with off and on sunshine for the rest of the week.