This weekend's weather forecast includes higher freezing levels and rain to mid-mountain elevations. This will have a destabilizing effect on the snowpack with avalanches increasing in size and frequency.
Summary
Confidence
Fair - Freezing levels are uncertain on Friday
Weather Forecast
Thursday Night: Up to 5cm of snow / Moderate westerly winds / Freezing level at about 1200mFriday: Light snowfall / Moderate to strong southwest winds / Freezing level at 1000m climbing to about 1800m in the eveningSaturday: 5-10cm of snow at higher elevations / Moderate to strong southwest winds / Freezing level at about 2000mSunday: Up to about 30cm of snow at higher elevations / Moderate to strong southwest winds / Freezing level up to about 2000m
Avalanche Summary
On Wednesday widespread storm snow avalanches to size 2 were reported. On the west side of the region where storm accumulations were higher a few natural and explosive triggered avalanches to size 3 were also noted.In recent days, 3 persistent slab avalanches in the 2-2.5 range were triggered naturally or remotely in the Invermere area. On Wednesday on the west side of the region (across the Lake from Kaslo) a size 2.5 persistent slab avalanche was remotely triggered from a distance of 20m. The slide was 150m wide, 150m long and 160cm deep at its widest point. The February 10th interface was responsible for these persistent slab avalanches.
Snowpack Summary
Recent snowfall amounts have been highly variable throughout the region. In some deeper snowpack areas over 80cm of storm snow overlies weak surface hoar in sheltered areas, a sun crust on solar aspects and wind slabs in exposed terrain. On lee slopes these accumulations have been pushed into much deeper deposits by generally moderate southwest winds. Warming has added cohesion to the slab and wider propagations can be expected. At lower elevations rain has likely moistened snow surfaces.There is ongoing concern for a mix of weak surfaces which were buried on February 10th. This persistent interface lies between 60 and 160cm below the surface, and includes surface hoar, well developed facets and a mix of hard surfaces which remain widespread at all aspects and elevations. In some areas destructive avalanches are still a very real concern with ongoing reports of natural triggering, whumpfing and sudden/easy snowpack test results. The mid and lower snowpack are generally strong and well consolidated. Weak basal facets exist in many areas, but triggering has now become unlikely.
jlammers,
Avalanche Canada
