The next wave of the storm puts us back in snowpack building mode. Keep avoiding avalanche terrain in the alpine and keep your guard up everywhere else.
A crust / facet layer from mid-November was buried 50 to 120 cm deep before this storm. It's especially reactive on wind-loaded, north-facing features. Wet slabs have been failing at this layer and storm slabs could step down to it.
Continuing heavy snowfall is expected to perpetuate a widespread natural avalanche cycle on Tuesday.
Wet loose avalanches may release naturally or with a human trigger in steep terrain where the snow surface is moist or wet.
A natural wet slab avalanche cycle to size 3 has been observed in the Whistler area after around 70 mm of rain below 2000 m and heavy alpine snow in the past 24 hours. Monday morning, new size 1.5 wet loose releases were observed and explosives produced a size 2 wet slab. The largest releases likely involved the November crust as a failure plane.
Looking forward, heavy snowfall and warm temperatures are expected to perpetuate more activity of a similar nature.
Roughly 30 - 40 cm of new snow should accumulate above about 1200 m by end of day Tuesday, blanketing a rain-soaked snowpack to 2000 m and adding to somewhat uncertain dry 24-hour snow accumulations in higher alpine locations. A reactive new storm slab problem should be the result.
A crust with facets, formed in mid-November, was buried 60-120 cm deep, depending on the aspect, before the storm. Monday's rain will continue to promote destructive avalanches at this layer. Forecast heavy snowfall prevents us from gaining much confidence in it, even as temperatures cool.
Monday Night
Cloudy with easing precipitation bringing 15 to 20 cm of new snow. 40 km/h southwest ridgetop wind. Treeline temperature -5 °C. Freezing level bottoms out at 1100 m.
Tuesday
Cloudy with increasing snowfall bringing 15 to 25 cm of new snow. 30 - 40 km/h south ridgetop wind, increasing. Treeline temperature around -2 °C. Freezing level 1200 - 1400 m.
Wednesday
Mostly cloudy with scattered flurries adding up to 5 cm after 30 - 40 cm overnight. 20 - 40 km/h southwest ridgetop wind. Treeline temperature -5 °C. Freezing level 1100 m.
Thursday
Mostly cloudy with increasing flurries bringing 10 to 25 cm of new snow, including overnight amounts. 40 km/h south ridgetop wind. Treeline temperature -2 °C. Freezing level rising from 1000 to 1400 m.
More details can be found in the Mountain Weather Forecast.
