The sun at this time of year can pack a punch so avoid exposure to cornices and watch for signs of warming in recent snow on steep south aspects. Fresh wind slabs on west to south aspects will likely be triggerable by riders. Thin rocky areas remain a concern for triggering deeply buried weak layers, especially as temperatures warm up through the week.
Recent snow and wind have reverse-loaded fresh wind slabs into atypical terrain features. Watch for wind drifted snow below ridge crests and rollovers and in cross-loaded terrain.
Weak, sugary crystals at the bottom of the snowpack produced large avalanches over a week ago. These avalanches are most likely to be triggered by large loads such as cornice falls. However, in shallow snowpack areas they can also be triggered by the weight of a person and could propagate out to deeper snow resulting in large, destructive avalanches.
No new avalanches have been reported since last week when the region saw numerous natural wind slab and cornice-triggered avalanches up to size 2.
On Tuesday our field team observed a size 3 deep persistent slab avalanche near Hankin that they estimated to be around a week old. The slab propagated across the full steep, rocky feature. This has been the latest of a pattern of intermittent large deep persistent slab activity in the alpine. Observations from late February include a cornice-triggered size 2.5 at Hudson Bay and several explosive controlled size 2-3 near Ningunsaw.
10-20 cm of recent wind affected snow sits over previously wind-hardened surfaces in the alpine. Sun crust or moist snow can be found on steep solar aspects.
Several crusts, layers of facets, or surface hoar can be found in the top 150 cm of the snowpack, but have not shown any significant avalanche activity or snowpack test results recently.
The lower snowpack consists of weak, basal facets which may become active with any rapid change or shock to the snowpack, such as heavy loading or dramatic warming.
Wednesday night
Clear. Light southeast wind. Alpine low -18 ˚C.
Thursday
Sunny. Light variable wind. Alpine high -10 ˚C.
Friday
A mix of sun and cloud. Strong southeasterly wind. Alpine high -12 ˚C.
Saturday
A mix of sun and cloud. Moderate easterly wind. Alpine high -15 ˚C.
More details can be found in the Mountain Weather Forecast.
