Warm temperature and sunshine will destabilize the snowpack throughout the day, especially on steep slopes that are baking in the sun. Timing, thoughtful terrain choices and conservative decision-making are essential for safe travel in the backcountry.
Warm temperatures may cause cornices to become weak. Cornice failures are dangerous on their own, but also have the potential to trigger larger avalanches on the slopes below.
This layer is getting harder for riders to trigger, but it is possible that it could still produce large, surprising avalanches. Triggering may be more likely when temperatures are above zero, or when they rapidly change in either direction.
This layer is a concern where there is a poor bond to underlying surface hoar crystals. This problem seems most pronounced in the Selkirks around Nelson and Kootenay Pass.
Wtih minimal overnight cooling forecasted, the surface snow may not solidly refreeze at lower elevations. Pay close attention to how thick and supportive the surface crust is throughout the day, and avoid steep slopes when they are baking in the sun. This will help you avoid wet loose avalanche problems.
A frontal wave draped across southern B.C. will keep the southeast regions mostly dry for Sunday.
SATURDAY NIGHT: Mainly cloudy. No precipitation. 10-15 km/h southerly winds. Low alpine temperature 0 C with freezing level around 2200 m.
SUNDAY: Cloudy with sunny periods. No precipitation. 10-15 km/h southerly winds. High alpine temperature +8 C with freezing level around 2700 m.
MONDAY: Cloudy with sunny periods and isolated showers. Trace of precipitation. 15-25 km/h southwesterly winds. High alpine temperature +6 C with freezing level around 2200 m.
TUESDAY: A mix of sun and cloud. No precipitation. 15-20 km/h northeasterly winds. Hig alpine temperature +4 C with freezing level around 2000 m.
On Friday, a large (size 3) avalanche was remotely triggered by a vehicule on an east facing slope around treeline and the low alpine. It may have started as a small avalanche that stepped down to deeper preserved buried surface hoar from late January and early March.
Also, numerous loose wet and wet slab avalanches up to size 2.5 were triggered by explosives on solar aspects.
Recent snow and moderate wind have formed small isolated pockets of windslab in the high alpine. Refrozen crust on all aspects as high as 2500 m, softening in the afternoon at low elevations and on steep, sunny slopes. Recent warm temperatures, sun, and rain have made the top 10-30 cm of the snowpack moist. At very low elevations, the snowpack may be wet and isothermal, depending on overnight freezing levels.
40 to 70 cm below the snow surface, you'll find a frozen sun crust on solar aspects, and weak, feathery surface hoar crystals on shaded aspects. This layer was buried in early March. During the last storm, and on the warmest days earlier this week, it produced surprising avalanches in the Selkirks (east side of the region). The recent warm weather may help this layer bond in the long run, but it's not yet time to take it out of your danger assessment for the day.
The mid and lower snowpack are generally strong and well bonded.
