Small avalanches can have big consequences in extreme terrain or when terrain traps are present.
Use extra caution on slopes with cornices overhead.
Soft, isolated pockets of wind slab formed during a brief period of moderate wind on Monday. Wind slabs may be most easily triggered where they sit over a sun crust on solar aspects.
Solar triggered cornice failures are possible and can trigger slabs on slopes below.
A layer of potentially weak crystals including facets, surface hoar and crust was buried at the end of February. As overlying snow gains slab properties slab avalanches on this layer could become more likely.
Wednesday night: no new snow expected. Moderate northwest winds. Low of -18 in the north and -11 in the south of the range.
Thursday: A mix of sun and cloud. Light to moderate west wind. High of -7 at 1800m.
Friday: A mix of sun and cloud with light flurries bringing trace amounts of new snow. Light to moderate west wind. Freezing level rising to 1500 m.
Saturday: cloudy with light flurries bringing up to 5cm of new snow. Light to moderate southwest winds with freezing levels rising to 1800m.
Human triggered avalanche activity has largely tapered off since Friday when several riders triggered storm slabs and loose dry avalanches in the recent snow, including this remotely triggered size 1.5 near Golden.
Solar triggered avalanche activity has been ongoing since the weekend. Countless loose dry avalanches up to size 1.5 have been reported out of steep or extreme terrain throughout the region as well as a few cornice failures up to size 3. Cornices and loose dry avalanches have also served as triggers for slabs on slopes below, including a size 2 reported on Tuesday near Invermere.
Warm temperatures Thursday through Sunday are suspected to have sensitized buried weak layers such that large explosives were able to trigger a few deep avalanches:
Surface snow has likely seen some redistribution and reverse-loading by recent northerly wind in the alpine. These soft wind slabs may sit over recently formed crusts on solar aspects and below 1500 m.
In the south of the region, a well bonded rain crust may be found within the top 30 cm up to 1700 m. A more widespread recently buried weak layer sits 30-60 cm deep throughout the region. It consists of surface hoar in shady, wind-sheltered areas and a sun crust on solar aspects.
An interface from mid-February composed of sun crust and/or surface hoar is now 30-90 cm deep. Explosive work near Invermere (where it is less than 60 cm deep) on Sunday confirmed that this layer can still be triggered by large loads.
A layer of surface hoar from late January has not produced recent avalanche activity but crystals can still be identified 40-50 cm deep near Golden.
