Avalanche Forecast

Moderate -

Thursday: Mainly clear skies / Moderate to strong northwest winds / Alpine temperature of -18Friday: Overcast skies with light flurries / Moderate to strong westerly winds / Alpine temperature of -12Saturday: 3-8cm of new snow / Light and variable winds / Alpine temperature of -14

In Rogers Pass on Monday, skiers remotely triggered a size 3.5 persistent slab avalanche from 40 m away on a south-facing, cross-loaded slope at 2600 m. Although deeper, persistent avalanche activity is becoming less frequent, this avalanche points to the continued reactivity and destructive potential of these layers. On the same day, explosives control in the Monashees triggered more persistent slab avalanche activity to size 3 in north to east facing alpine terrain. Recently formed wind slabs to size 2 were also ski cut in wind-exposed, higher elevation terrain.Observations on Tuesday were more limited due to inclement weather, although I'm sure there was a natural storm slab cycle in response to new snow and wind.

By Wednesday morning up to 37cm of new snow had fallen. Wind data has been sparse, although I suspect strong winds shifted these accumulations into deeper, reactive slabs in wind-exposed terrain. These accumulations overlie a mix of older wind slabs in exposed higher elevation terrain, a sun crust on steep solar aspects, a rain crust below 1600m and surface hoar on sheltered slopes.Below the snow surface, several persistent weak layers make up a troublesome snowpack. In the top 1.5-2.5 m of the snowpack, two surface hoar layers buried in January can be found. Expect to find one or other of these on all aspects and elevations.Deeper in the snowpack (around 200 cm deep) is a facet/crust/surface hoar layer from December, most prevalent at and below treeline.Near the base of the snowpack is a crust/facet combo, most likely to be triggered from thin spots in the alpine.All of these layers have produced large avalanches recently. The wide distribution and ongoing reactivity of these layers suggests that avoidance through choosing simple terrain is the best strategy.