The avalanche danger in the mountains on B.C.’s south coast, the Sea to Sky region and in Alberta’s Jasper National Park is rated as extreme. The warning from Avalanche Canada says storms on Thursday and Friday will dump between 60 and 100 centimetres of fresh snow in those areas. The agency says the snow, combined with expected heavy rain or wind, will likely cause widespread storm slab avalanches in the Alpine and treeline areas of the Sea to Sky and south coast. The danger rating extends to below the treeline in Jasper and Avalanche Canada says snow slides were triggered on Wednesday both naturally and by skiers on the Columbia Icefields in the park. The extreme rating means that those who use the backcountry should avoid all avalanche terrain and that large, natural or human-triggered avalanches are certain. The mountain weather forecast says a front has stalled over southern B.C., pumping heavy doses of moisture over the same areas, and until that system moves it will keep raining and snowing.