60 to 100 cm of new snow over two days is a rapid load, and enough to bring a LOT of avalanche terrain online. Stick to simple or non-avalanche terrain that defends you from overhead hazards.
A crust / facet layer from November was buried 50 to 100 cm before the storm. Conditions have lent well to cleaning out and stabilizing the problem, but it may still be possible to trigger in thin-to-thick areas in the alpine.
Heavy snowfall will rapidly form a reactive storm slab problem for Thursday. The more snow accumulates and the more it is affected by wind, the greater the danger.
No new avalanches reported, but it's a safe bet that a natural cycle took place at the height of the Tues/Wed storm as up to 60 cm piled up. Below treeline areas are likely approaching or even above threshold.
Expect more active conditions with the next storm.
Last Wednesday, a size 3 stepped down to a deep weak layer near Allison Pass. It's a lone data point from before the atmospheric river, but leaves some questions about a possible lingering deep problem in high alpine.
30 to 45 cm of new snow should fall Wednesday night through Thursday, with the greatest amounts expected on the Coquihalla. Allison Pass may get missed.
The new snow will add to 35 to 60 cm from the Tuesday/Wednesday storm, which covers a crust forming on the rain-soaked snowpack below.
An older crust with facets, formed in mid-November, should now be about 80 to 150 cm deep in the alpine. The rain ought to have cleaned out this problem where it existed, but with few recent observations and loading ongoing, thin-to-thick snowpack areas in the high alpine remain a bit suspect.
Snowpack heights should reach about 140 to 200 cm by end of day Thursday. There's still not much snow below 1500 m.
Wednesday Night
Cloudy with increasing snowfall bringing 10 to 15 cm of new snow. 50 km/h southwest ridgetop wind. Treeline temperature -4 °C. Freezing level reaching 1100 m.
Thursday
Cloudy with increasing snowfall bringing 20 to 30 cm of new snow, easing overnight. 40 km/h south ridgetop wind jumping to 60 km/h near end of day. Treeline temperature reaching 0 °C when the freezing level jumps to 1600 m near end of day.
Friday
Cloudy with continuing snowfall bringing 25 to 35 cm of new snow, including overnight amounts. 40 to 60 km/h southwest ridgetop wind. Treeline temperature -5 °C. Freezing level 1000 m.
Saturday
Mostly cloudy with easing snowfall bringing 30 to 40 cm of new snow, including overnight amounts. 60 km/h southwest ridgetop wind. Treeline temperature -6 °C. Freezing level 1000 m.
More details can be found in the Mountain Weather Forecast.
