If warm temperatures persist, there will be a higher likelihood of avalanche activity, especially on steep, sun-exposed slopes.Are you a member of Avalanche Canada? Join today at avalanche.ca/membership
Weather Forecast
The ridge of high pressure will break down somewhat allowing for overcast skies and very light snowfall on Thursday and Friday. By Saturday the ridge will rebuild in all its glory bringing mainly sunny skies for the weekend. Freezing levels will hover at or near valley bottom for the forecast period, with ridge top winds remaining mainly light from the northwest.
Avalanche Summary
Under Monday's warm skies, loose wet avalanches to size 2 were observed in sun-exposed terrain. That said, observations were limited, and the warming may have had a more widespread effect. In the neighboring North Columbia region, warming and solar radiation triggered some persistent slab avalanches to size 3.5. Forecast cooling should limit avalanche activity of this nature.
Snowpack Summary
Generally light amounts of loose cold snow cover the previous variable snow surface of crusts, surface hoar, or wind affected snow depending on aspect and elevation. Thin wind slabs may still be sensitive to triggering in isolated high elevation lee terrain, and cornices remain large and weak. The 'Valentine's Day' crust, found just below the surface, is thick and supportive below 2100 m. The late-Jan crust/surface hoar layer can be found about a metre below the surface in deeper snowpack areas. The mid-January surface hoar, can be found below that. These layers have gained significant strength, and chances of triggering these weaknesses have decreased dramatically. However, triggering may be possible with a large input such as cornice fall, or an avalanche stepping down, especially on sun drenched slopes.
Problems
Persistent Slabs
Persistent Slab avalanches are the release of a cohesive layer of snow (a slab) in the middle to upper snowpack, when the bond to an underlying persistent weak layer breaks. Persistent layers include: surface hoar, depth hoar, near-surface facets, or faceted snow. Persistent weak layers can continue to produce avalanches for days, weeks or even months, making them especially dangerous and tricky. As additional snow and wind events build a thicker slab on top of the persistent weak layer, this avalanche problem may develop into a Deep Persistent Slab.