Regions
Banff Yoho Kootenay.
After the wind and later the sun triggered many avalanches today, cloudy skies and light winds are expected Saturday. Clearing Sunday however, marks the beginning of a significant warming trend that is expected to increase avalanche activity.
Weather Forecast
After a few patches of clear sky late in the day Friday, a return to more clouds seems likely for Saturday as winds diminish and temps stay largely static. Clearing skies midday Sunday looks to mark the beginning of a significant warming trend that will bring freezing levels to 3000m later in the week. An increase in avalanche activity is expected.
Snowpack Summary
15- 40cm has accumulated since March 7. Modertate to strong SW-W winds have redistributed this snow treeline and above. This snow sits over previous widespread wind effect in the alpine, suncrusts on steep S aspects and 30-50cm of sugary facets everywhere else. While a tough midpack exists in thicker areas, facets to ground are seen in many others.
Avalanche Summary
Fresh snow overnight, with moderate to strong winds led to a cycle Friday morning with slabs to sz 2.5 and loose dry avalanches to sz 1.5. As has been seen over the last week: the loose dry avalanches often entrain significant amounts of old faceted snow in steep terrain and continue to run until they hit lower angle terrain.
Confidence
Timing or intensity of solar radiation is uncertain on Sunday
Problems
Wind Slabs
Wind Slab avalanches are the release of a cohesive layer of snow (a slab) formed by the wind. Wind typically transports snow from the upwind sides of terrain features and deposits snow on the downwind side. Wind slabs are often smooth and rounded and sometimes sound hollow, and can range from soft to hard. Wind slabs that form over a persistent weak layer (surface hoar, depth hoar, or near-surface facets) may be termed Persistent Slabs or may develop into Persistent Slabs.
Loose Dry
Loose Dry avalanches are the release of dry unconsolidated snow and typically occur within layers of soft snow near the surface of the snowpack. These avalanches start at a point and entrain snow as they move downhill, forming a fan-shaped avalanche. Other names for loose-dry avalanches include point-release avalanches or sluffs.