Give the new snow time to bond. Heavy snowfall, wind, and a buried weak layer warrant conservative terrain choices on Thursday.
Avalanches in the recent snow could be bigger than expected, as some recent avalanches have propagated widely on 50 to 100 cm deep crust and surface hoar layers. The duration of this problem is uncertain.
A frontal system is bringing 20 to 40 cm of snow on Wednesday night into Thursday morning. Fresh slabs will be reactive to human triggering on steep slopes, especially those that are wind-loaded.
Tuesday saw widespread size 2 storm and wind slab avalanches. There were also notable reports of larger (size 2.5 to 3) human-triggered slabs northeast of Pemberton and in the Spearhead range. These avalanches involved 50 to 100 cm deep persistent weak layers that resulted in wide propagations and, in some cases, remote triggering.
We expect a natural avalanche cycle on Wednesday night, and then into Thursday both storm and persistent slabs will be a concern.
Snow, rain, and wind are reshaping snow surfaces. 20 to 40 cm of new snow on Thursday will add to the 50 to 100 cm of recent wind-affected snow at upper elevations. Treeline and below treeline elevations received more rain, leading to smaller snow totals. The recent snow sits above a layer of poorly bonded crusts and surface hoar, which has shown sensitivity to human triggers and snowpack tests. With ongoing rapid changes to the weather, it is uncertain how long this layer will remain a problem.
The lower snowpack is strong and bonded and total snow depths remain below average.
Wednesday Night
Cloudy with 15 to 25 cm of snow above 1200 m (rain below), alpine wind south 60 to 90 km/h, treeline temperature near -1 °C.
Thursday
Cloudy with 10 to 20 cm of snow above 1400 m (primarily in the morning then easing in the afternoon), alpine wind south 30 to 50 km/h, treeline temperature around 0 °C, freezing level climbing to 1700 m in the afternoon.
FridayMostly cloudy with 1 to 3 cm of snow, alpine wind southeast 50 to 70 km/h, treeline temperature around +2 °C with freezing level climbing to 2200 m.
SaturdayMostly cloudy with 2 to 8 cm of snow, alpine wind south 50 km/h, treeline temperature around 0 °C with freezing level dropping to 1800 m.
More details can be found in the Mountain Weather Forecast.
