Some fresh wind-slabs can be expected in immediate alpine lees on Wednesday. Keep the deep persistent layers in mind, especially on large alpine slopes.
Recent winds and forecasted strong winds winds are expected to form fresh wind slabs on lee slopes in the alpine. If triggered, these slabs could entrain facets, leading to longer-than-expected runouts.
The October and November crusts, on north and south aspects respectively, are still producing isolated slab avalanches down about 50-80 cm. Be mindful on steep, rocky alpine slopes where triggering is most likely.
Lake Louise patrol reported one skier controlled cornice that triggered a size 1 wind slab in the immediate lee of an alpine ridge.
The early-season snowpack at treeline measures 50-90 cm. In the alpine there is scouring on windward slopes and some fresh loading on immediate lee aspects. A surface crust or moist snow may exist on south aspects below 2500m. The November crust lies mid-pack on south aspects, while the main concern is the October crust near the ground on north aspects, where facets and depth hoar are forming. The snowpack is generally weak and facetted.
Mild temperatures and moderate winds with a possible above freezing layer in the alpine are the theme for Wednesday. Winds are expected to become strong by Friday. Valley bottom temperatures will rise to just above freezing. Winds will be in the 30-40 km/h range on Wednesday and becoming stronger on Thursday.
