Incoming snow, wind, and warming temperatures will increase avalanche hazard over the next several days.
Confidence
Moderate - Due to the number of field observations
Weather Forecast
WEDNESDAY: Snow starting late on Tuesday is forecast to provide 10 to 20 cm by Wed afternoon. Snow will coincide with moderate SW winds. Temperatures warming with freezing level rising to approximately 800 m.THURSDAY: Continued snow with another 20 to 30 cm by evening, still accompanied by moderate to strong SW winds. Temperatures slightly warmer with freezing level peaking around 1000 m. FRIDAY: Still snowing with another 15 to 25 cm by Friday evening with moderate SW winds easing to light W. Temperatures cooling slightly with freezing level falling to 700 m.
Avalanche Summary
Only small sluffing reported. With an incoming storm forecast the potential for slab avalanches (wind slab and storm slabs) will increase.
Snowpack Summary
Below the 20 cm of recent snow, the previous snow surface was a mix of sun crust on southerly aspects and surface hoar on shaded aspects with bonds beginning to strengthen. The widespread 20 cm thick mid-February rain crust, is now down around 40-60 cm at higher elevations. Below the crust, the snowpack is well settled and strong. Forecast incoming snow (starting Tuesday overnight) suggests at higher elevations there will be fresh wind slabs on north and east facing slopes, and when there is more than 20 cm of new snow also expect to find storm slabs on steeper slopes, even where wind protected.
Problems
Wind Slabs
Wind Slab avalanches are the release of a cohesive layer of snow (a slab) formed by the wind. Wind typically transports snow from the upwind sides of terrain features and deposits snow on the downwind side. Wind slabs are often smooth and rounded and sometimes sound hollow, and can range from soft to hard. Wind slabs that form over a persistent weak layer (surface hoar, depth hoar, or near-surface facets) may be termed Persistent Slabs or may develop into Persistent Slabs.