Weather Forecast
A high pressure ridge will continue to bring dry, warm conditions.Friday and Saturday: An inversion will generate an above freezing layer from around 1800 to 3200m. Expect some cloud around 1800 m as well as some strong alpine sunshine. Alpine temperatures will reach around +5C and will feel higher still in the sunshine. Ridgetop winds 20-30 km/h from the NW.Sunday: A cooler day as far as air temperatures go, but cloud dissipating, so treeline areas may actually feel warmer. Winds light northerly.
Avalanche Summary
On Tuesday, two size 2.5 avalanches released on the same slope about 50 m apart. They failed to ground and it is thought that one released naturally and the other released sympathetically in response to the first. These have been the only avalanches reported since a sporadic cycle of larger avalanches running on weak basal layers ended on Saturday 18th.
Snowpack Summary
Snowpack depths vary, but in general there is now 200 to 250cm of snow at tree line and as much as 300 cm in select places in the alpine. In the south and to the east of the region, there are still areas with a relatively thin snowpack. The recent dry, warm weather has generally consolidated the upper snowpack. Old, stubborn hard wind slabs may exist under a skiff of new snow. Steep, sun exposed features are most likely seeing a daily melt-freeze cycle, that could see new snow shed readily, especially where it overlies recently buried surface hoar that lies approximately 10 cm under the surface.A basal facet/crust combo (weak sugary snow above and below a crust) near the ground is still a concern in some areas, and was the culprit with some of the very large recent avalanches. Likely triggers at this interface would include cornice fall, rapid temperature changes or thin spot triggering on an unsupported alpine or treeline elevation slope.
Problems
Deep Persistent Slabs
Deep Persistent Slab avalanches are the release of a thick cohesive layer of hard snow (a slab), when the bond breaks between the slab and an underlying persistent weak layer deep in the snowpack. The most common persistent weak layers involved in deep, persistent slabs are depth hoar or facets surrounding a deeply buried crust. Deep Persistent Slabs are typically hard to trigger, are very destructive and dangerous due to the large mass of snow involved, and can persist for months once developed. They are often triggered from areas where the snow is shallow and weak, and are particularly difficult to forecast for and manage.