Rain and high freezing levels can trigger avalanches on buried weak layers.
Avoid all avalanche terrain during periods of high hazard.
A weak layer from early March is now 150 to 230 cm deep with January and February layers buried 200 to 300 cm. These remain a concern, especially in northerly alpine terrain.
Weak layers can become reactive when loaded due to rain or warming.
Storm snow and moderate southwest winds has formed reactive slabs. Expect to find deeper and more reactive deposits on north- and east-facing slopes at upper elevations, where the wind will load lee slopes.
Rain-on-snow and warm temperatures can rapidly destabilize the snowpack.
Wet loose avalanches can trigger slab avalanches that fail on deeper snow or weak layers.
We expect avalanche activity to continue with both wet and large slab avalanches being easy to trigger during this warm period.
On Sunday, numerous human-triggered size 1.5 storm slabs like this one occurred in the alpine and upper treeline.
On Saturday near Whistler, a natural cornice fall triggered a size 3 slab on the slope below.
On Friday, an explosive-triggered size 2 storm slab was reported on the early March melt-freeze crust, on an east-facing slope in the alpine.
We have received up to 30 mm of recent precipitation; snow above 1500 m and rain below this elevation. Expect deeper and more reactive deposits on north—and east-facing slopes. This overlies 40 cm of recent snow. Expect to find rain-soaked or moist snow below 1500 m.
This overlies 50 cm of settled snow and then a melt-freeze crust on southerly slopes and at lower elevations.
A weak layer formed in early March found down 150 to 230 cm, consists of a crust on all aspects except high north-facing slopes. In some areas, a layer of surface hoar is found just above the crust.
Weak layers formed in mid-February and late January are now buried 200 to 300 cm deep.
Below this, the snowpack is well-settled and strong.
Monday Night
Cloudy with up to 15 mm, falling as snow above 1500 m. 20 to 40 km/h south ridgetop winds. Treeline temperature 0 °C.
Tuesday
Cloudy with 5 mm, falling as snow above 2500 m. 30 to 50 km/h southwest ridgetop winds. Treeline temperature 4 °C. Freezing level rises to 2500 m.
Wednesday
Mostly cloudy with trace precipitation. 40 km/h southeast ridgetop winds. Treeline temperature 6 °C. Freezing level 3000 m.
Thursday
Cloudy with 25 to 40 mm, falling as snow above 1500 m. 50 km/h southeast ridgetop winds. Treeline temperature 0 °C.
More details can be found in the Mountain Weather Forecast.
