Avalanche Forecast

Moderate - Due to the number of field observations

Expect 5-15cm of new snow to fall between Friday night and Saturday. An additional 5cm may fall on Sunday, while isolated flurries and sunny breaks are forecast for Monday. Winds on Saturday will be strong from the southwest, and then drop to light and northwesterly for Sunday and Monday. Freezing levels should hover between 500-700m for the entire forecast period.

On Thursday, persistent and storm slab avalanches to size 3.5 were observed on a variety of aspects and elevations. They occurred in response to heavy storm loading from rain and snow. The mid-January surface hoar was the suspected culprit in many of these avalanches. Of note was a size 4 slab avalanche in Steep Creek in the Duffey Lake area. Thanks to the individual who submitted this great observation through the Mountain Information Network. Moving forward, cooling will likely put a cap on persistent slab avalanche activity, except on higher elevation slopes in the north of the region where reactivity is expected to persist. Forecast wind and snow will spark a new round of wind slab activity in high elevation lee terrain over the weekend.

On Wednesday night and Thursday morning, heavy snowfall and strong winds continued to form deep and dense storm slabs in high elevation terrain and cause substantial cornice growth. The snow line fluctuated a great deal during the storm which dropped around 80mm of precipitation throughout the region. At treeline and below, heavy rain saturated the snowpack. With forecast cooling, slopes at these elevation bands may now be sporting a hard crust. Where it still exists, the mid-January surface hoar layer is between 60 and 130 cm below the surface. The combination of heavy storm loading and warm temperatures has likely flushed out this weak layer in many areas. I would still exercise caution on higher elevation slopes in the north of the region where continued reactivity at this destructive interface is likely to persist. New snow and wind on Friday night and Saturday will form new wind slabs in high elevation lee terrain.