Eastern regions of Banff Park received the most snow this week, with up to 20 cm falling in the Canmore area and more expected through the week. This means that ice climbs on Mt. Rundle, Cascade Mountain and Sulphur Mountain have now reached a threshold for avalanches over the climbs. Natural activity has slowed over the past 24 hours, but human triggering remains likely where a deep enough snowpack exists.
Another 5-10 cm of low-density snow on Wednesday will create small windslabs in leeward areas. If triggered, these slabs could step down to the deeper facet layers and result in a larger than expected avalanche.
Recent snow and wind loading has created slabs over a persistent weak layer of facets, buried sun crusts, or isolated pockets of surface hoar. This slab has been sensitive to natural and human triggering and can result in full depth avalanches.
Nothing was reported on Tuesday, but on Monday a size 2 skier triggered avalanche failed on the ground adjacent Lake Louise ski area, along with a surface hoar avalanche near Sunshine and two size 2-2+ Na avalanches on the 93N that appear to have failed on the basal facets.
25-30 cm of storm snow has accumulated over the past 7 days at treeline that has now settled into a slab overlying a mix of weak facets, surface hoar, or sun crust on steep south aspects (ie: very weak base). 40-80 cm of total snow exists at treeline throughout the region, with up to 120 cm in loaded alpine features.
An arctic ridge of high pressure remains anchored in Alberta while a low-pressure system moves across BC starting Wed night and through the day on Wed. This will produce 5-10 cm of snow in most of the region by Wed while temperatures remain cold (-20ish) and winds light from the south. No warm-up is expected for at least another week.
More details can be found in the Mountain Weather Forecast.
