Winter came hard to the valley this season, and the order in which the snow has accumulated has prompted special public avalanche warnings.
The Purcell Mountains have had a complex early season snowpack, said Tom Riley, avalanche forecaster for Avalanche Canada.
On Tuesday, December 30th, a special warning was extended to Sunday, January 4th by Avalanche Canada throughout most of the provinces inland regions (including the Purcells and Rockies regions), which cautions backcountry users over the increased likelihood of triggering avalanches.
Initially issued on Thursday, December 25th, the warning said that pre-Christmas snowfalls, in addition to strong winds and mixed temperatures, has placed a heavy load on a fragile snowpack.
The decision to extend the warning was tricky, Mr. Riley said, as forthcoming weather could have many different effects on the current stagnating conditions.
But last weeks warning is still in place.
People who are going out into the backcountry are likely to very likely to trigger avalanches, he said. The conditions that we issue the special avalanche warning for, which is a buried surface hoar layer thats resulting in large avalanches that are very easy to trigger, that can be difficult for people in the public to analyze.
While local conditions are improving slightly, the dangers caused by underlying layers of surface hoars will still be present.
It was quite an active period for avalanches in the Purcells during the special warning, said Mr. Riley, adding that many, which were triggered by human activity, happened remotely. The motion of travel by recreational users is able to disrupt the snowpack up to 40 metres away from the person.
One benefit of those conditions, he said, is that people are triggering them from safer spots.
Between Monday, December 29th and Friday,January 2nd, reports in the Purcells indicated considerable avalanche danger above the treeline. While the level of danger could be rated two degrees higher (on a scale of five), December was a period of heightened avalanche activity, he said.
Theres been a lot of cold, clear weather, followed by warm and even rain at high elevations.
Under the current conditions, Mr. Riley recommends that the backcountry only be used by those with experience, and hopes people will carry the proper safety gear an avalanche transceiver, probe and shovel along with training and practice with the tools.
If you dont have the education to identify this kind of terrain and weak layers, you should recreate somewhere thats taken care of for you, like a ski hill or guided operation, he said.
For those who are braving the backcountry, he suggests users scale back and stay on low-angle terrain.
Right at treeline, about 300 to 500 metres wide, has been the most reactive place, he said.
Looking ahead, Mr. Riley said sudden changes in the weather are likely to increase the level of avalanche danger while gradual weather changes are more conduscive to backcountry use. Conditions are updated daily online at www.avalanche.ca.